anterior

Anterior sacral meningocele

Anterior sacral meningocele

Anterior sacral meningoceles are congenital lesions that consist of a spinal fluid-filled sac in the pelvis communicating by a small neck with the spinal subarachnoid space through a defect in the sacrum. They protrude into retroperitoneal and presacral space. 1) 2).

The wall of the sac consists of two layers, an inner arachnoid membrane and outer dura mater, which extends into the retroperitoneal presacral space from the sacral spinal canal 3).

Anterior sacral meningocele was first described in 1837 as a part of neural tube defect (NTD) spectrum.

It may be associated with a syndrome like Currarino syndrome 4) which includes anorectal malformations, sacral bony defect and presacral mass; and Marfan syndrome wherein the etiology may be disorder of collagen biosynthesis and structure at the dural level 5).

Epidemiology

Anterior sacral meningocele epidemiology

Anterior sacral meningocele in Marfan syndrome

Anterior sacral meningocele in Marfan syndrome

Classification

Anterior sacral meningocele classification.

Etiology

Anterior sacral meningocele etiology.

Pathology

Associated malformations are found:

spina bifida

spinal dysraphism

bicornuate uterus

imperforate anus 6).

Clinical features

Anterior sacral meningocele clinical features.

Diagnosis

Anterior sacral meningocele diagnosis.

Differential diagnosis

Anterior sacral meningocele differential diagnosis.

Complications

Anterior sacral meningocele complications.

Treatment

Anterior Sacral Meningocele Treatment.

Case reports

Anterior sacral meningocele case reports.

1)

Villarejo F, Scavone C, Blazquez MG, Pascual-Castroviejo I, Perez-Higueras A, Fernandez-Sanchez A, Garcia Bertrand C. Anterior sacral meningocele: review of the literature. Surg Neurol. 1983 Jan;19(1):57-71. doi: 10.1016/0090-3019(83)90212-4. PMID: 6828997.
2)

Sharma V, Mohanty S, Singh DR. Uncommon craniospinal dysraphism. Ann Acad Med Singap. 1996 Jul;25(4):602-8. PMID: 8893940.
3)

Somuncu S, Aritürk E, Iyigün O, Bernay F, Rizalar R, Günaydin M, Gürses N. A case of anterior sacral meningocele totally excised using the posterior sagittal approach. J Pediatr Surg. 1997 May;32(5):730-2. doi: 10.1016/s0022-3468(97)90018-x. PMID: 9165463.
4)

CALIHAN RJ. Anterior sacral meningocele. Radiology. 1952 Jan;58(1):104-8. doi: 10.1148/58.1.104. PMID: 14883380.
5)

North RB, Kidd DH, Wang H. Occult, bilateral anterior sacral and intrasacral meningeal and perineurial cysts: case report and review of the literature. Neurosurgery. 1990 Dec;27(6):981-6. doi: 10.1097/00006123-199012000-00020. PMID: 2274142.
6)

Dahan H, Arrivé L, Wendum D, Docou le Pointe H, Djouhri H, Tubiana JM. Retrorectal developmental cysts in adults: clinical and radiologic-histopathologic review, differential diagnosis, and treatment. Radiographics. 2001 May-Jun;21(3):575-84. doi: 10.1148/radiographics.21.3.g01ma13575. PMID: 11353107.

Bilateral anterior cingulotomy

Bilateral anterior cingulotomy

Bilateral anterior cingulotomy is a form of psychosurgery, introduced in 1948 as an alternative to lobotomy.

Lesioning of the target area is typically performed using bilateral stereotactic electrode placement and target ablation, which involves transparenchymal access through both hemispheres.

Lauri Laitinen was a pioneer of stereotactic psychosurgery in the 1950s to 1970s, especially by introducing the subgenual cingulotomy.

Indications

Bilateral anterior cingulotomy has been used to treat chronic pain, obsessive-compulsive disorder.

In the early years of the twenty-first century, it was used in Russia to treat addiction.

The objective of this surgical procedure is the severing of the supracallosal fibers of the cingulum bundle, which pass through the anterior cingulate gyrus.

Early localizationists linked anterior cingulate cortex (ACC: Brodmann’s area 24 and adjacent regions) with emotional behavior, paving the way for bilateral cingulotomy psychosurgery in severe, treatment resistant, cases of obsessive-compulsive disorder, chronic pain, depression, and substance abuse.

Limbic system surgery based on initial cingulotomy offers a durable and effective treatment option for appropriately selected patients with severe obsessive compulsive disorder who have not responded to conventional pharmacotherapy or psychotherapy 1).

There are features of anterior cingulate cortex structure and connectivity that predict clinical response to dorsal anterior cingulotomy for refractory obsessive compulsive disorder. These results suggest that the variability seen in individual responses to a highly consistent, stereotyped procedure may be due to neuroanatomical variation in the patients. Furthermore, these variations may allow us to predict which patients are most likely to respond to cingulotomy, thereby refining our ability to individualize this treatment for refractory psychiatric disorders 2)

The presence of neuropathic pain can severely impinge on emotional regulation and activities of daily living including social activities, resulting in diminished life satisfaction. Unfortunately, the majority of patients with neuropathic pain do not experience an amelioration of symptoms from conventional therapies, even when multimodal therapies are used. Chronic refractory neuropathic pain is usually accompanied by severe depression that is prone to incur suicidal events; thus clinical management of chronic neuropathic pain and depression presents a serious challenge for clinicians and patients

Two patients presented with neuropathic pain and severe depression. The patients had different pain symptoms emerging a few months after central or peripheral nervous system impairment. These symptoms were associated with the development of severe depression, social isolation, and a gradual inability to perform daily activities. Both patients were referred for bilateral anterior cingulotomy. After surgery, both patients showed significant progressive improvements in perceived pain, mental health status, and daily functioning.

Bilateral anterior cingulotomy may serve as an alternative treatment for medically refractory neuropathic pain, especially for patients who also experience depression 3).

Stereotactic anterior cingulotomy has been used in the treatment of patients suffering from refractory oncological pain due to its effects on pain perception. However, the optimal targets as well as suitable candidates and outcome measures have not been well defined. We report our initial experience in the ablation of 2 cingulotomy targets on each side and the use of the Brief Pain Inventory (BPI) as a perioperative assessment tool.

A retrospective review of all patients who underwent stereotactic anterior cingulotomy in our Department between November 2015 and February 2017 was performed. All patients had advanced metastatic cancer with a limited prognosis and suffered from intractable oncological pain.

Thirteen patients (10 women and 3 men) underwent 14 cingulotomy procedures. Their mean age was 54 ± 14 years. All patients reported substantial pain relief immediately after the operation. Out of the 6 preoperatively bedridden patients, 3 started ambulating shortly after. At the 1-month follow-up, the mean preoperative Visual Analogue Scale score decreased from 9 ± 0.9 to 4 ± 2.7 (p = 0.003). Mean BPI pain severity and interference scores decreased from levels of 29 ± 4 and 55 ± 12 to 16 ± 12 (p = 0.028) and 37 ± 15 (p = 0.043), respectively. During the 1- and 3-month follow-up visits, 9/11 patients (82%) and 5/7 patients (71%) available for follow-up reported substantial pain relief. No patient reported worsening of pain during the study period. Neuropsychological analyses of 6 patients showed stable cognitive functions with a mild nonsignificant decline in focused attention and executive functions. Adverse events included transient confusion or mild apathy in 5 patients (38%) lasting 1-4 weeks.

The initial experience indicates that double stereotactic cingulotomy is safe and effective in alleviating refractory oncological pain 4).

Case series

Four MRgLITT bilateral cingulotomy procedures were performed in 3 patients. Two patients had a single MRgLITT procedure while the third had repeat ablation after pain recurrence. First time ablation coordinates were (medians): x = 7.9 mm (range, 6.9-8.6); y = 20.5 mm (range, 20-22); z = 6.9 mm (range, 2.9-7.0) above the lateral ventricle roof. Median trajectory length was 85.5 mm (range, 80-90). Median ablation volume was 1.5 cm3 (range, 0.6-1.2). Median ablation time was 257 seconds (range, 136-338) per cingulum and power was 10.0 Watts (range, 10-11). Median preoperative pain severity (PSS) and interference scores (PIS) were 7.7 (range, 7.5-9.3) and 9.9 (range, 9.7-10.0), respectively. Median postoperative PSS and PIS scores were 1.6 (range, 1.0-2.8) and 2.0 (range, 0.3-2.6), respectively.

MRgLITT cingulotomy is well tolerated for treatment of cancer pain and can be easily performed framelessly for appropriate candidates 5).

Seven patients suffering from refractory OCD underwent stereotactic surgery and were followed for 12 months. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was used to assess the efficacy. The test was taken before and 6 and 12 months after surgery.

The mean Y-BOCS scores decreased significantly from 32.9 ± 4.7 at baseline to 20.6 ± 5.3 after 12 months. Five out of the 7 patients showed a decrease of more than 35%. During the 12-month follow-up, the effective rate had increased from 28.6 to 71.4%. There were no significant adverse effects observed after surgery.

The BACI and BACA were effective for the treatment of refractory OCD, and no significant adverse effects on long-term follow-up were found 6).

Bilateral radiofrequency cingulotomy was performed in 10 patients. The technique involved stereotaxis using magnetic resonance guidance and local anesthesia, with the placement of a radiofrequency lesion (75 degrees, 60s). Of the 10 patients, 8 had metastatic lesions with musculoskeletal (6) or neurogenic (2) pain. Pain relief was judged excellent (4 patients), fair (1), poor (2) and excellent for 6 months poor in the last patient. The two benign lesions were neurofibromatosis with neurogenic pain and thalamic pain from an old stroke. Pain relief (with 1 year follow-up) in this group was judged excellent in one and poor in the other (thalamic pain) 7).

Forty-two patients out of 300 who had undergone bilateral stereotactic cingulotomies were studied by means of computerized tomography (CT). The appearance showed bilateral encephalomalacia, measuring on the average 5 X 7 mm2, located in the cingulate gyrus. These induced lesions had attenuation values similar to cerebrospinal fluid and did not enhance with contrast. CT is a useful technique for initial evaluation, management, and follow up of these patients 8).

Case reports

In end-stage cancer, oncologic pain refractory to medical management significantly reduces patient’s quality of life. In recent years, ablative surgery has seen a resurgence in treating diffuse and focal cancer pain in terminal patients. The anterior cingulate gyrus has been a key focus as it plays a role in the cognitive and emotional processing of pain. While radiofrequency ablation of the dorsal anterior cingulate is well-described for treating cancer pain, MRI-guided laser-induced thermal therapy (LITT) is novel. Allam et al. describes a patient treated with an MRI-guided LITT therapy of the anterior cingulate gyrus for intractable debilitating pain secondary to terminal metastatic cancer 9).

Huotarinen et al., found 1 patient alive who underwent subgenual cingulotomy in 1971 for obsessive thoughts, anxiety, and compulsions, diagnosed at that time as “schizophrenia psychoneurotica.” MRI showed bilateral subgenual cingulotomy lesions (254 and 160 mm3, respectively). The coordinates of the center of the lesions in relation to the midcommissural point for the right and left, respectively, were: 7.1 and 7.9 mm lateral; 0.2 mm inferior and 1.4 mm superior, and 33.0 and 33.9 anterior, confirming correct subgenual targeting. The patient reported retrospective satisfactory results.

The lesion in this patient was found to be in the expected location, which gives some verification of the correct placement of Laitinen’s subgenus cingulotomy target 10).

A case of debilitating thoracic wall pain due to malignant mesothelioma relieved by bilateral anterior cingulotomy is described and changes in dyspnoea investigated.

Improvements in pain, dyspnoea and the extent to which either symptom bothered the patient was seen for 2 months after surgery before disease progression led to death 5 months after surgery. Quality of life improvements were also seen for 2 months after surgery and pain relief was sustained from surgery to death. Arterial blood gas and lung function tests were unchanged by surgery, suggesting a reduction in pain and dyspnoea awareness by cingulotomy.

Bilateral anterior cingulotomy effectively relieved both pain and dyspnoea. The role of the anterior cingulate cortex in pain and autonomic control of respiration is discussed alongside the evidence for this palliative procedure for cancer pain 11).

Books

by Ernest. Feigenbaum (Author)

References

1)

Sheth SA, Neal J, Tangherlini F, Mian MK, Gentil A, Cosgrove GR, Eskandar EN, Dougherty DD. Limbic system surgery for treatment-refractory obsessive-compulsive disorder: a prospective long-term follow-up of 64 patients. J Neurosurg. 2013 Mar;118(3):491-7. doi: 10.3171/2012.11.JNS12389. Epub 2012 Dec 14. PubMed PMID: 23240700.
2)

Banks GP, Mikell CB, Youngerman BE, Henriques B, Kelly KM, Chan AK, Herrera D, Dougherty DD, Eskandar EN, Sheth SA. Neuroanatomical Characteristics Associated With Response to Dorsal Anterior Cingulotomy for Obsessive-Compulsive Disorder. JAMA Psychiatry. 2014 Dec 23. doi: 10.1001/jamapsychiatry.2014.2216. [Epub ahead of print] PubMed PMID: 25536384.
3)

Deng Z, Pan Y, Li D, Zhang C, Jin H, Wang T, Zhan S, Sun B. Effect of Bilateral Anterior Cingulotomy on Chronic Neuropathic Pain with Severe Depression. World Neurosurg. 2019 Jan;121:196-200. doi: 10.1016/j.wneu.2018.10.008. Epub 2018 Oct 10. PubMed PMID: 30315971.
4)

Strauss I, Berger A, Ben Moshe S, Arad M, Hochberg U, Gonen T, Tellem R. Double Anterior Stereotactic Cingulotomy for Intractable Oncological Pain. Stereotact Funct Neurosurg. 2018 Jan 10;95(6):400-408. doi: 10.1159/000484613. [Epub ahead of print] PubMed PMID: 29316566.
5)

Patel NV, Agarwal N, Mammis A, Danish SF. Frameless stereotactic magnetic resonance imaging-guided laser interstitial thermal therapy to perform bilateral anterior cingulotomy for intractable pain: feasibility, technical aspects, and initial experience in 3 patients. Neurosurgery. 2015 Mar;11 Suppl 2:17-25; discussion 25. doi: 10.1227/NEU.0000000000000581. PubMed PMID: 25584953.
6)

Zhang QJ, Wang WH, Wei XP. Long-term efficacy of stereotactic bilateral anterior cingulotomy and bilateral anterior capsulotomy as a treatment for refractory obsessive-compulsive disorder. Stereotact Funct Neurosurg. 2013;91(4):258-61. doi: 10.1159/000348275. Epub 2013 May 7. PubMed PMID: 23652367.
7)

Pillay PK, Hassenbusch SJ. Bilateral MRI-guided stereotactic cingulotomy for intractable pain. Stereotact Funct Neurosurg. 1992;59(1-4):33-8. PubMed PMID: 1295044.
8)

Bernad PG, Ballantine HT. Computed tomographic analysis of bilateral cingulotomy for intractable mood disturbance and chronic pain. Comput Radiol. 1987 May-Jun;11(3):117-23. PubMed PMID: 3301189.
9)

Allam AK, Larkin MB, Katlowitz KA, Shofty B, Viswanathan A. Case report: MR-guided laser induced thermal therapy for palliative cingulotomy. Front Pain Res (Lausanne). 2022 Nov 1;3:1028424. doi: 10.3389/fpain.2022.1028424. PMID: 36387414; PMCID: PMC9663803.
10)

Huotarinen A, Kivisaari R, Hariz M. Laitinen’s Subgenual Cingulotomy: Anatomical Location and Case Report. Stereotact Funct Neurosurg. 2018;96(5):342-346. doi: 10.1159/000492058. Epub 2018 Oct 2. PubMed PMID: 30278436.
11)

Pereira EA, Paranathala M, Hyam JA, Green AL, Aziz TZ. Anterior cingulotomy improves malignant mesothelioma pain and dyspnoea. Br J Neurosurg. 2014 Aug;28(4):471-4. doi: 10.3109/02688697.2013.857006. Epub 2013 Nov 7. PubMed PMID: 24199940.

Anterior communicating artery aneurysm endovascular treatment complications

Anterior communicating artery aneurysm endovascular treatment complications

Intraprocedural aneurysm rupture and thrombus formation are serious complications during coiling of ruptured intracranial aneurysms, and they more often occur in patients with anterior communicating artery aneurysms.

It is associated with a high rate of complete angiographic occlusion. However, the procedure-related permanent morbidity and mortality are not negligible for aneurysms in this location 1).

Delgado Acosta et al. from Hospital Universitario Reina Sofía aimed to report the characteristics of patients suffering intra- or peri-procedural ruptures during embolization of cerebral aneurysms.

Between March 1994 and October 2021, 648 consecutive cerebral aneurysms were treated by the endovascular procedure. Medical records were reviewed retrospectively with emphasis on procedure description, potential risk factors, and clinical outcomes related to intra- or peri-procedural rupture.

Of the 648 patients, 17 (2.6%) suffered an intra- or peri-procedural hemorrhagic event. The most common location was the anterior communicating artery. There was no significant difference between previously ruptured and unruptured aneurysms in the incidence of bleeding. In four patients, bleeding was evident within 24 h after the procedure. The clinical evolution at three months was poor and only four patients presented a positive evolution. There were 11 deaths (64.71%). Balloon remodeling was associated with an increased frequency of ruptures, while stenting was a safer treatment.

Aneurysm rupture during endovascular therapy is unpredictable, and its occurrence can be devastating. The incidence is quite low although the outcome is frequently poor. Early detection and proper management, including prompt occlusion of the aneurysm, are important to achieve a positive outcome. Anterior communicating artery aneurysms and those treated with balloon catheters have a higher incidence of rupture. A small number of ruptures of uncertain origin occur that go unnoticed in digital subtraction angiograms 2).

The immediate and long-term outcomes, complications, recurrences and the need for retreatment were analyzed in a series of 280 consecutive patients with anterior communicating artery aneurysms treated with the endovascular technique. From October 1992 to October 2001 280 patients with 282 anterior communicating artery aneurysms were addressed to our center. For the analysis, the population was divided into two major groups: group 1, comprising 239 (85%) patients with ruptured aneurysms and group 2 comprising of 42 (15%) patients with unruptured aneurysms. In group 1, 185 (77.4%) patients had a good initial pre-treatment Hunt and Hess grade of I-III. Aneurysm size was divided into three categories according to the larger diameter: less than 4 mm, between 4 and 10 mm and larger than 10 mm. The sizes of aneurysms in groups 1 and 2 were identical but a less favorable neck to depth ratio of 0.5 was more frequent in group 2. Endovascular treatment was finally performed in 234 patients in group 1 and 34 patients in group 2. Complete obliteration was more frequently obtained in group 2 unlike a residual neck or opacification of the sac that were more frequently seen in group 1. No peri-treatment complications were recorded in group 2. In group 1 the peri-treatment mortality and overall peri-treatment morbidity were 5.1% and 8.1% respectively. Eight patients (3.4%) in group 1 presented early post treatment rebleeding with a mortality of 88%. The mean time to follow-up was 3.09 years. In group 1, 51 (21.7%) recurrences occurred of which 14 were minor and 37 major. In group 2, eight (23.5%) recurrences occurred, five minor and three major. Two patients (0.8%) presented late rebleeding in group 1. Twenty-seven second endovascular retreatments were performed, 24 (10.2%) in group 1 and three (8.8%) in group 2, seven third endovascular retreatments and two surgical clippings in group 1 only. There was no additional morbidity related to retreatments. Endovascular treatment is an effective method for the treatment of anterior communicating artery aneurysms allowing late rebleeding prevention. Peri-treatment rebleeding warrants caution in anticoagulation management. This is a single center experience and the follow-up period is limited. Patients should be followed-up in the long-term as recurrences may occur and warrant additional treatment 3).

Prolonged anterograde amnesia and disorientation after anterior communicating artery aneurysm coil embolization 4)

LVIS stent-assisted coiling for ruptured wide-necked ACoA aneurysms was safe and effective, with a relatively low rate of perioperative complications and a high rate of complete occlusion at follow-up 5)

1)

Fang S, Brinjikji W, Murad MH, Kallmes DF, Cloft HJ, Lanzino G. Endovascular treatment of anterior communicating artery aneurysms: a systematic review and meta-analysis. AJNR Am J Neuroradiol. 2014 May;35(5):943-7. doi: 10.3174/ajnr.A3802. Epub 2013 Nov 28. PMID: 24287090; PMCID: PMC7964525.
2)

Delgado Acosta F, Bravo Rey I, Jiménez Gómez E, Saucedo VR, Toledano A, Oteros Fernández R. Intra- or peri-procedural rupture in the endovascular treatment of intracranial aneurysms. Acta Neurol Scand. 2022 Aug 17. doi: 10.1111/ane.13686. Epub ahead of print. PMID: 35975464.
3)

Finitsis S, Anxionnat R, Lebedinsky A, Albuquerque PC, Clayton MF, Picard L, Bracard S. Endovascular treatment of ACom intracranial aneurysms. Report on series of 280 patients. Interv Neuroradiol. 2010 Mar;16(1):7-16. doi: 10.1177/159101991001600101. Epub 2010 Mar 25. PMID: 20377974; PMCID: PMC3277962.
4)

Al-Atrache Z, Friedler B, Shaikh HA, Kavi T. Prolonged anterograde amnesia and disorientation after anterior communicating artery aneurysm coil embolisation. BMJ Case Rep. 2019 Jul 30;12(7). pii: e230543. doi: 10.1136/bcr-2019-230543. PubMed PMID: 31366616.
5)

Xue G, Liu P, Xu F, Fang Y, Li Q, Hong B, Xu Y, Liu J, Huang Q. Endovascular Treatment of Ruptured Wide-Necked Anterior Communicating Artery Aneurysms Using a Low-Profile Visualized Intraluminal Support (LVIS) Device. Front Neurol. 2021 Jan 28;11:611875. doi: 10.3389/fneur.2020.611875. PMID: 33584512; PMCID: PMC7876256.

terior communicating artery aneurysm endovascular treatment complications

Anterior odontoid screw fixation indications

Anterior odontoid screw fixation indications

Anterior odontoid screw fixation (AOSF) and posterior occipitocervical fusion are both well-accepted techniques for surgical treatment but with unique indications and contraindications as well as varied reported outcomes.

Joaquim et al. reviewed the literature about specific patients and fracture characteristics that may guide treatment toward one technique over the other. AOSF can preserve atlantoaxial motion, but requires a reduced odontoid, an intact transverse ligament, and a favorable fracture line to achieve adequate fracture compression. Additionally, older patients may have a higher rate of pseudarthrosis using this technique, as well as postoperative dysphagia. posterior occipitocervical fusion has a higher rate of fusion and is indicated in patients with severe atlantoaxial misalignment and with poor bone quality. posterior occipitocervical fusion allows direct open reduction of displaced fragments and can reduce any atlantoaxial instability. It is also used as a salvage procedure after failed AOSF. However, this technique results in loss of atlantoaxial motion, requires prone positioning, and demands a longer operative duration than AOSF, factors that can be a challenge in patients with severe medical conditions. Although both anterior and posterior approaches are acceptable, many clinical and radiological factors should be taken into account when choosing the best surgical approach. Surgeons must be prepared to perform both procedures to adequately treat these injuries 1)

Full-Endoscopic Anterior Odontoid Screw Fixation is a feasible and effective option for Odontoid fracture type II treatment. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures 2).

Direct anterior screw fixation is an effective and safe method for treating recent odontoid fractures (<6 months postinjury). It confers immediate stability, preserves C1-2 rotatory motion, and achieves a fusion rate that compares favorably with alternative treatment methods. In contradistinction, in patients with remote fractures (> or = 18 months postinjury), a significantly lower rate of fusion is found when using this technique, and these patients are believed to be poor candidates for this procedure 3).

Although anterior screw fixation is the ideal choice for type Ⅱ odontoid fractures with anterior superior to posterior inferior fracture line, it may not be the best choice for comminuted or fracture end hardened type Ⅱ odontoid fractures 4).

1)

Joaquim AF, Patel AA. Surgical treatment of Type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion? Neurosurg Focus. 2015 Apr;38(4):E11. doi: 10.3171/2015.1.FOCUS14781. PMID: 25828487.
2)

Kotheeranurak V, Pholprajug P, Jitpakdee K, Pruttikul P, Chitragran R, Singhatanadgige W, Limthongkul W, Yingsakmongkol W, Kim JS. Full-Endoscopic Anterior Odontoid Screw Fixation: A Novel Surgical Technique. Orthop Surg. 2022 Apr 20. doi: 10.1111/os.13271. Epub ahead of print. PMID: 35445547.
3)

Apfelbaum RI, Lonser RR, Veres R, Casey A. Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg. 2000 Oct;93(2 Suppl):227-36. PubMed PMID: 11012053.
4)

Yang S, Liu YJ, Jiang WM. Experience in surgery treatment of type Ⅱ odontoid fractures: A report of two cases and review of the literature. Chin J Traumatol. 2019 Nov 1. pii: S1008-1275(19)30333-5. doi: 10.1016/j.cjtee.2019.10.003. [Epub ahead of print] PubMed PMID: 31757743.

Anterior sacral meningocele in Marfan syndrome

Anterior sacral meningocele in Marfan syndrome

Twenty-four Marfan and 2 Loeys-Dietz patients had anterior sacral meningocele at follow-up, compared with 21 and 1, respectively, at baseline. Three Marfan patients developed herniation of a nerve root sleeve during follow-up. This was not seen in other individuals. The dural sac ended significantly lower at follow-up, and the dural sac ratio at level L5 was significantly increased from baseline in the Marfan patients.

In Marfan and Loeys-Dietz syndrome, dural ectasia may present or worsen during adulthood. The cut-off value of dural sac ratio at level S1 is suggested elevated to 0.64. The results from the present study may help as guidance for appropriate follow-up of patients with dural ectasia 1).

Case reports

A case of a 46-year-old woman who presented with urinary incontinence, early satiety, and back pain in the setting of a known anterior sacral meningocele. Before operative management, the anterior sacral meningocele ruptured with the patient presenting signs and symptoms of intracranial hypotension. Conservative management did not alleviate the pain. She was ultimately managed with posterior sacroplasty followed by anterior sacral meningocele resection and placement of a lumboperitoneal shunt. The patient did not have reaccumulation of the meningocele or recurrent symptoms at the latest follow-up.

The progression of dural ectasia in Marfan syndrome to an anterior sacral meningocele is uncommon. It is important to identify the characteristics associated with an expanding dural ectasia as this patient’s symptoms progressed over time and the meningocele grew large. Given its rarity, there are no guidelines in place regarding size at which repair of an anterior sacral meningocele should occur prophylactically. It is important to review these cases in order continue to learn about progression, management, and outcomes of patients with an anterior sacral meningocele. 2).

A 43-year-old woman with a history of Marfan syndrome and a large ASM was referred for neurosurgical intervention. The ASM was filling the pelvic cavity and causing severe compression of the bladder. The patient underwent surgical decompression of the cyst through an anterior transabdominal approach and closure of the fistulous tract with a pedicled omental flap. This is the first reported case of successful closure of an ASM with an omental flap. At the 6-month follow-up, the ASM had not recurred on imaging and the patient’s symptoms had resolved. Anterior sacral meningoceles are rare lesions that often require neurosurgical intervention. Although most can be treated posteriorly, large ASMs compressing the abdominal or pelvic organs may require a transabdominal approach. Moreover, ASMs with wide dural stalks may benefit from closure with an omental flap. 3).

A 43-year-old man diagnosed with Marfan syndrome suffered sacrococcygeal trauma. He was admitted to the emergency room due to symptoms of headache, nausea, and lower limb subjective weakness. CT and MRI showed a large retroperitoneal mass with hemorrhagic content close to the sacrum. Likewise, the MRI showed an image compatible with subarachnoid hemorrhage in the thoracic spinal area, cerebral convexity, and the basal cisterns. The patient went into surgery for an anterior abdominal approach in the midline to reduce the content of the lesion, and subsequently, in the same act, a posterior approach was done with an S1-S2 laminectomy and obliteration of the pedicle. Postoperative MRI 5 months later showed resolution of the ASM.

Anterior sacral meningocele is characterized by herniation of the dura mater and the arachnoid mater outside the spinal canal through a defect of the sacrum. We add the risk of bleeding after trauma-never seen in the literature-as one of the possible inherent complications of this lesion.

This report highlights a complication never seen in the literature of a relatively rare condition. In our case, the combined approach was effective for both clinical control and lesion regression. 4).

A patient with Marfan’s syndrome and ASMs who was referred to gynaecology owing to dysmenorrhoea and left-sided pelvic pain radiating to the left leg. A transvaginal ultrasound scan (TVUS) detected a left pelvic cystic tubular structure, attributed to a hydrosalpinx, which, in retrospect, likely corresponded to the ASM. The patient went on to have TVUS-guided drainage of this cystic structure, resulting in an ASM abscess. It is difficult to distinguish ASM from the vastly more common hydrosalpinx using TVUS alone, and in patients with an atypical appearing posteriorly positioned cystic pelvic lesion or in the presence of underlying conditions known to be associated with ASMs, MRI should be considered before any interventional procedure to drain the suspected hydrosalpinx transvaginally. The patient was successfully treated using a minimally invasive CT-guided posterior trans-sacral drainage technique. 5).

A 20-year old female with Marfan syndrome who presented with abdominal distention that was misdiagnosed as an ovarian cyst on pelvic ultrasound. Pelvic magnetic resonance (MR) imaging showed large, well-defined multiloculated intrasacral and presacral cysts communicating via two separate broad necks and extending through defects in anterior aspect of sacral vertebrae. This case emphasizes that anterior sacral meningocele should be considered in the differential diagnosis of cases with pelvic cysts particularly in patients with underlying connective tissue disorders. Because severe neurologic complications or even death may occur without proper preoperative planning in such cases, MR imaging should always be performed for evaluation and characterization of pelvis cystic lesions. 6).

A young woman with Marfan syndrome who was being treated with anticoagulants for a prosthetic heart valve and who presented with a spontaneous retroperitoneal hemorrhage requiring surgical evacuation. No CSF leak was encountered at surgery, but she developed progressively more severe positional headaches over the following year. She then experienced the sudden onset of acute urinary obstruction, at which time CT revealed a 17 × 15 × 13-cm presacral pseudomeningocele communicating with the thecal sac through a sacral bone defect. An anterior surgical approach was used for drainage of the pseudomeningocele as well as for primary closure of the dural defect with a bovine pericardial patch and autologous subcutaneous fat graft. After a short period of lumbar subarachnoid drainage of the CSF, the patient was able to resume normal activity without recurrent symptoms. To the authors’ knowledge, such a pseudomeningocele in a patient with Marfan syndrome has been reported only twice, and this case features the largest pseudomeningocele to date. They also review the pertinent literature regarding presentation, diagnosis, and management of these lesions. 7).

Relapse of Escherichia coli meningitidis due to sacral meningocele in Marfan syndrome, treated only with antibiotherapy 8).

Surgical Treatment of Anterior Sacral Meningoceles in Patients with Marfan Syndrome: A Report of Three Cases 9).

A case of bacterial meningitis secondary to fistulous communication between a sacral meningocele and sigmoid colon in the setting of diverticulitis 10).

Five women who underwent laparoscopic transperitoneal surgery were clinically, radiologically, and surgically evaluated.

Result: All 5 patients underwent laparoscopic transperitoneal surgery and showed satisfactory results. They had no major complications. Three patients had headaches as minor complications, but it was gone in at most 3 days. Decrease in operative time, blood loss, and length of hospitalization were the advantages of the procedure.

The laparoscopic approach to treating anterior sacral meningocele was feasible and safe, with only minor complications. 11).

A woman with Marfan’s syndrome presenting with a clinical picture of acute gastroenteritis in whom severe bilateral hydroureteronephrosis associated to a neurogenic bladder and a giant anterior sacral meningocele was diagnosed incidentally. The importance of this case lies in the fact that the patient was asymptomatic despite the significant visceral repercussions already occurring that led to questioning of whether MRI follow-up would still be advisable even in the absence of symptoms. 12).

A 46-year-old woman with Marfan’s syndrome exhibiting an incomplete Currarino triad and recurrent bacterial meningitis which recurred three times in about six months. An anterior sacral meningocele (ASM) was noted in a lumbar MRI, and multiple bone defects in the sacrum were noted in 3D-CT. Surgical approach to prevent the recurrence of infection was limited to plasty for the meningocele, but no meningitis has been observed for two years. Radical surgery should be considered in cases with ASM who recurred bacterial meningitis. 13).

A 52 year old woman with Marfan syndrome who presented with a significantly large anterior sacral meningocele without having associated symptoms. In light of this case, we recommend that asymptomatic Marfan patients with dural ectasia should be closely observed without need for immediate surgical intervention 14).

18-year-old man with Marfan syndrome, diagnosed upon MRI morphological evaluation which showed a huge cystic mass in the pelvic space. Surgical excision even if curative was not performed in consideration of a stationary picture after one year since diagnosis. 15).

Two cases presenting as nongynaecological pelvic masses are described highlighting the clinical difficulty in diagnosis and the classical radiological findings 16).

Anterior sacral meningocele presenting as a pelvic/abdominal mass in a patient with Marfan syndrome 17).

The first case of a giant anterior sacral meeningocele rapidly cured by a simple endoscopic procedure 18). The postoperative course of the patient was characterized by immediate disappearance of the preoperative clinical signs. Computed tomographic scans demonstrated progressive complete collapse of the anterior sacral meningocele and partial resolution of the intrasacral component 19).

A marfanoid patient underwent celiotomy for a pelvic mass and was found to have an anterior sacral meningocele. Nine years prior to that time she had undergone surgery because of a “sacrococcygeal cyst,” which in retrospect seemed to be a posterior meningocele 20).

Purulent meningitis from surgical inoculation of an anterior sacral meningocele 21).

Anterior sacral meningocele in association with Marfan’s syndrome 22).

1)

Böker T, Vanem TT, Pripp AH, Rand-Hendriksen S, Paus B, Smith HJ, Lundby R. Dural ectasia in Marfan syndrome and other hereditary connective tissue disorders: a 10-year follow-up study. Spine J. 2019 Aug;19(8):1412-1421. doi: 10.1016/j.spinee.2019.04.010. Epub 2019 Apr 15. PMID: 30998996.
2)

Hollenberg AM, Baldwin AL, Mesfin A, Silberstein H. Rupture of Giant Anterior Sacral Meningocele in a Patient with Marfan Syndrome: Diagnosis and Management. World Neurosurg. 2018 Nov;119:137-141. doi: 10.1016/j.wneu.2018.07.249. Epub 2018 Aug 6. PMID: 30092475.
3)

Paisan GM, Crandall KM, Chen S, Burks SS, Sands LR, Levi AD. Closure of a giant anterior sacral meningocele with an omental flap in a patient with Marfan syndrome: case report. J Neurosurg Spine. 2018 Aug;29(2):182-186. doi: 10.3171/2018.1.SPINE171303. Epub 2018 May 25. PMID: 29799321.
4)

Gilete-Tejero IJ, Ortega-Martínez M, Mata-Gómez J, Rico-Cotelo M, Bernal- García LM, Yerga-Lorenzana B, Casado-Naranjo I. Anterior sacral meningocele presenting as intracystic bleeding. Eur Spine J. 2018 Jul;27(Suppl 3):276-280. doi: 10.1007/s00586-017-5128-1. Epub 2017 May 18. PMID: 28523383.
5)

Jawad S, Ejindu V, Johnson D, Shah MA, Abbasi MA, Ojha K, Papadakos N. Transvaginal ultrasound-guided aspiration of an anterior sacral meningocele masquerading as a hydrosalpinx, resulting in abscess formation. BJR Case Rep. 2016 Sep 3;3(1):20160037. doi: 10.1259/bjrcr.20160037. PMID: 30363340; PMCID: PMC6159307.
6)

Sahin N, Genc M, Kasap E, Solak A, Korkut B, Yilmaz E. Anterior Sacral Meningocele Masquerading as an Ovarian Cyst: A Rare Clinical Presentation Associated with Marfan Syndrome. Clin Pract. 2015 Apr 24;5(2):752. doi: 10.4081/cp.2015.752. PMID: 26236457; PMCID: PMC4500879.
7)

Stone JG, Bergmann LL, Takamori R, Donovan DJ. Giant pseudomeningocele causing urinary obstruction in a patient with Marfan syndrome. J Neurosurg Spine. 2015 Jul;23(1):77-80. doi: 10.3171/2014.11.SPINE131086. Epub 2015 Apr 24. PMID: 25909269.
8)

Bigaré M, Lesaffre X, Delassus JL, Bakir R, Bouldouyre MA. Rechute de méningite à Escherichia coli due à un méningocèle sacré dans le cadre d’une maladie de Marfan, traitée par antibiothérapie prolongée seule [Relapse of Escherichia coli meningitidis due to sacral meningocele in Marfan syndrome, treated only with antibiotherapy]. Presse Med. 2014 Jan;43(1):93-5. French. doi: 10.1016/j.lpm.2013.02.330. Epub 2013 Jul 19. PMID: 23876649.
9)

Ebnet J, Krauss JK, Lorenz M, Bektas H, Nakamura M. Surgical Treatment of Anterior Sacral Meningoceles in Patients with Marfan Syndrome: A Report of Three Cases. JBJS Case Connect. 2012 Apr-Jun;2(2):e16. doi: 10.2106/JBJS.CC.K.00040. PMID: 29252417.
10)

Samet JD, Johnson PT, Horton KM, Fishman EK. Diverticulitis complicated by fistulous communication of sigmoid colon with anterior sacral meningocele in a patient with Marfan syndrome. Radiol Case Rep. 2015 Dec 7;7(1):442. doi: 10.2484/rcr.v7i1.442. PMID: 27326266; PMCID: PMC4899866.
11)

Trapp C, Farage L, Clatterbuck RE, Romero FR, Rais-Bahrami S, Long DM, Kavoussi LR. Laparoscopic treatment of anterior sacral meningocele. Surg Neurol. 2007 Oct;68(4):443-8; discussion 448. doi: 10.1016/j.surneu.2006.11.067. PMID: 17905071.
12)

Santana JM, Gómez A, Alemán P, Travieso MM. Ureterohidronefrosis severa asociada a meningocele sacro anterior gigante asintomático: presentación de un caso y revisión de la literatura [Severe hydroureteronephrosis associated to asymptomatic giant anterior sacral meningocele: a case report and review of the literature]. Radiologia. 2007 Jan-Feb;49(1):43-6. Spanish. doi: 10.1016/s0033-8338(07)73715-3. PMID: 17397621.
13)

Hatano A, Akiyama K, Nagayama M, Takagi S. [Case of Marfan’s syndrome with anterior sacral meningocele along with recurring bacterial meningitis]. Rinsho Shinkeigaku. 2006 Sep;46(9):658-60. Japanese. PMID: 17260811.
14)

Nallamshetty L, Ahn NU, Ahn UM, Nallamshetty HS, Rose PS, Buchowski JM, Sponseller PD. Dural ectasia and back pain: review of the literature and case report. J Spinal Disord Tech. 2002 Aug;15(4):326-9. doi: 10.1097/00024720-200208000-00012. PMID: 12177551.
15)

Rigante D, Segni G. Anterior sacral meningocele in a patient with Marfan syndrome. Clin Neuropathol. 2001 Mar-Apr;20(2):70-2. PMID: 11327300.
16)

Voyvodic F, Scroop R, Sanders RR. Anterior sacral meningocele as a pelvic complication of Marfan syndrome. Aust N Z J Obstet Gynaecol. 1999 May;39(2):262-5. doi: 10.1111/j.1479-828x.1999.tb03390.x. PMID: 10755797.
17)

Schneider MB, Dittmar S, Boxer RA. Anterior sacral meningocele presenting as a pelvic/abdominal mass in a patient with Marfan syndrome. J Adolesc Health. 1993 Jun;14(4):325-8. doi: 10.1016/1054-139x(93)90182-o. PMID: 8347646.
18)

Raftopoulos C, Delecluse F, Braude P, Rodesh C, Brotchi J. Anterior sacral meningocele and Marfan syndrome: a review. Acta Chir Belg. 1993 Jan- Feb;93(1):1-7. PMID: 8470436.
19)

Raftopoulos C, Pierard GE, Rétif C, Braude P, Brotchi J. Endoscopic cure of a giant sacral meningocele associated with Marfan’s syndrome: case report. Neurosurgery. 1992 May;30(5):765-8. doi: 10.1097/00006123-199205000-00020. PMID: 1584392.
20)

Barter JF, Addison WA, Rosenberg ER, Hammond CB. Anterior sacral meningocele presenting as a pelvic mass and diagnosed only at celiotomy after an extensive workup. A case report. J Reprod Med. 1983 Oct;28(10):684-6. PMID: 6655630.
21)

le Mercier Y, Decazes JM, Mechali D, Redondo A, Aboulker J, Coulaud JP. Méningite purulente par inoculation chirurgicale d’une méningocèle sacrée antérieure. Une complication rare de la maladie de Marfan [Purulent meningitis from surgical inoculation of an anterior sacral meningocele: a rare complication of Marfan’s disease (author’s transl)]. Ann Med Interne (Paris). 1980;131(5):289-90. French. PMID: 7004305.
22)

Strand RD, Eisenberg HM. Anterior sacral meningocele in association with Marfan’s syndrome. Radiology. 1971 Jun;99(3):653-4. doi: 10.1148/99.3.653. PMID: 5578713.

Unruptured anterior communicating artery aneurysm rupture risk

Unruptured anterior communicating artery aneurysm rupture risk

Although the research on the risk factors of anterior communicating artery aneurysm has made great progress, the independent effect of each risk factor on the rupture of AComA aneurysm is controversial among different studies. For this answer Xie et al. will present the results employing the random effects model. Quality assessment of the included studies will be evaluated using the Newcastle–Ottawa Scale. Statistical analyses will be performed using Stata16 (Stata Corporation, College Station, TX, USA) software.The findings of this study will be submitted to peer-reviewed journals for publication. This systematic review will provide evidence to determine the risk factors that affect the rupture of the AComA aneurysm and quantify their independent effects 1).

Ma et al. found that larger size, greater size ratio, larger flow angle, irregular shape, and smoking of the patient were associated with the rupture of ACoA aneurysms based on univariate analysis. Size ratio (OR = 3.890, P = 0.003), irregular shape (OR = 1.068, P = 0.001), flow angle (OR = 1.054, P = 0.001), and current smoking (OR = 4.435, P = 0.009) were the strongest factors related to ruptured ACoA aneurysms based on multivariate logistic regression analysis. The areas under the curves for the flow angle and size ratio were 0.742 (95% CI 0.646-0.838; P = 0.001) and 0.736 (95% CI 0.621-0.796; P = 0.001), respectively. The strongest risk factors for rupture include size ratio, irregular shape, flow angle, and current smoking. These features should be taken into consideration to aid in the prediction of the rupture risk of ACoA aneurysms 2).

Multiple logistic regression model revealed that A1 dominance [odds ratio (OR) 3.034], an irregular shape (OR 3.358), and an aspect ratio ≥1.19 (AR; OR 3.163) increased the risk of rupture, while cerebral atherosclerosis (OR 0.080), and mean diameters ≥2.48 mm (OR 0.474) were negatively correlated with ACoAA rupture. Incorporating these five factors, the ROC analysis revealed that the threshold value of the multifactors was one, the sensitivity was 88.3%, and the specificity was 66.0%. The scoring model is a simple method that is based on A1 dominance, irregular shape, aspect ratio, cerebral atherosclerosis, and mean diameters from CTA and is of great value in the prediction of the rupture risk of ACoAAs 3).

According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (AC) aneurysms of <7 mm in diameter have a minimal risk of rupture. It is general experience, however, that anterior communicating artery (AcoA) aneurysms are frequent and mostly rupture at <7 mm. Bijlenga et al. found that AC aneurysms are not a homogenous group. Aneurysms between 4 and 7 mm located in AcoA or distal anterior cerebral artery present similar rupture odds to posterior circulation aneurysms. Intervention should be recommended for this high-risk lesion group 4).

For Matsukawa et al. the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm 5).

Aneurysms found unruptured in the ACoA show a risk of rupture twice as high as that of other intracranial aneurysms (95% confidence interval, 1.29-3.12). It is the first time this fact has been demonstrated based on the follow-up of unruptured aneurysms.

When deciding whether to operate on UIAs located in the ACoA, surgeons should consider their higher risk of rupture 6).

1)

Xie Y, Tian H, Xiang B, Li D, Liu YZ, Xiang H. Risk factors for anterior communicating artery aneurysm rupture: A protocol for systematic review and meta-analysis. Medicine (Baltimore). 2021 Dec 3;100(48):e28088. doi: 10.1097/MD.0000000000028088. PMID: 35049234.
2)

Ma X, Yang Y, Liu D, Zhou Y, Jia W. Demographic and morphological characteristics associated with rupture status of anterior communicating artery aneurysms. Neurosurg Rev. 2020 Apr;43(2):589-595. doi: 10.1007/s10143-019-01080-w. Epub 2019 Jan 31. PMID: 30706157.
3)

Wang GX, Wang S, Liu LL, Gong MF, Zhang D, Yang CY, Wen L. A Simple Scoring Model for Prediction of Rupture Risk of Anterior Communicating Artery Aneurysms. Front Neurol. 2019 May 31;10:520. doi: 10.3389/fneur.2019.00520. PMID: 31214103; PMCID: PMC6554323.
4)

Bijlenga P, Ebeling C, Jaegersberg M, Summers P, Rogers A, Waterworth A, Iavindrasana J, Macho J, Pereira VM, Bukovics P, Vivas E, Sturkenboom MC, Wright J, Friedrich CM, Frangi A, Byrne J, Schaller K, Rufenacht D; @neurIST Investigators. Risk of rupture of small anterior communicating artery aneurysms is similar to posterior circulation aneurysms. Stroke. 2013 Nov;44(11):3018-26. doi: 10.1161/STROKEAHA.113.001667. Epub 2013 Jul 30. PMID: 23899912.
5)

Matsukawa H, Uemura A, Fujii M, Kamo M, Takahashi O, Sumiyoshi S. Morphological and clinical risk factors for the rupture of anterior communicating artery aneurysms. J Neurosurg. 2013 May;118(5):978-83. doi: 10.3171/2012.11.JNS121210. Epub 2012 Dec 14. PMID: 23240701.
6)

Mira JM, Costa FA, Horta BL, Fabião OM. Risk of rupture in unruptured anterior communicating artery aneurysms: meta-analysis of natural history studies. Surg Neurol. 2006;66 Suppl 3:S12-9; discussion S19. doi: 10.1016/j.surneu.2006.06.025. PMID: 17081844.

Anosmia after anterior communicating artery aneurysm surgery

Anosmia after anterior communicating artery aneurysm surgery

Pathogenesis

For Bor et al. anosmia occurs after coiling in 1 of every 6 SAH patients, but has a good prognosis in most patients. The cause of anosmia after coiling for ruptured aneurysms remains elusive; severity of the initial hemorrhage or long lasting hydrocephalus may be contributing factors 1).

In patients with subarachnoid hemorrhage (SAH), anosmia has mainly been reported after surgery for anterior communicating artery aneurysms. Olfactory dysfunction after SAH caused by rupture of the ACoA are very frequent and were present in both treatment groups (aneurysmal clip placement and coil embolization).

Cerebral vasospasm and frontal lobe lesions are related to worse performance on an olfactory test in patients undergoing endovascular coil embolization 2).

Both clip treatment and SAH contribute to the occurrence of anosmia, with different chances of improvement. Olfactory dysfunction occurs in almost all patients on the side of surgery and can occur subclinically after coil deployment 3).

Its occurrence after coiling suggests not only damage to the olfactory nerve by clipping but also that the SAH itself plays a role in its pathogenesis 4).

The highest incidence of olfactory dysfunction following a pterional approach and its modifications for an intracranial aneurysm has been reported in cases of anterior communicating artery (ACoA) aneurysms. The radiological characteristics of unruptured ACoA aneurysms affecting the extent of retraction of the frontal lobe and olfactory nerve were investigated as risk factors for postoperative olfactory dysfunction. In cases of unruptured ACoA aneurysm surgery, the height of the aneurysm neck and the estimated extent of brain retraction were both found to be powerful predictors of the occurrence of postoperative olfactory dysfunction. 5).

Wongsuriyanan and Sriamornrattanakul published that the interhemispheric approach provided an excellent surgical corridor for clipping anterior communicating artery aneurysms (AcoAAs). However, an important disadvantage of the approach is obtaining proximal control at A1 in the last stage of dissection, especially in anterior or superior projecting AcoAAs and ruptured cases.

Postoperative anosmia was detected in 22.7% 6).

For Ito et al. the causes of postoperative anosmia in subfrontal and interhemispheric approach were as follows: sectioning of olfactory tracts intentionally or not, avulsion of olfactory bulbs and probability of ischemic or minor mechanical insults to olfactory tracts. However, these matters rarely occur in posterior interhemispheric approach because of little exposure of olfactory nerves. The mechanisms of postoperative anosmia in posterior interhemispheric approach were considered to be as follows: sinking of frontal lobes due to excessive drainage of cerebrospinal fluid and over-retraction of frontal lobes. The incidence of postoperative anosmia decreased from 27.0% via subfrontal and interhemispheric approach to 5.5% via posterior interhemispheric approach 7).

Prevention

Superior direction of aneurysm appears associated with postoperative olfactory dysfunction. Olfactory protection using gelfoam and fibrin glue could be a simple, safe, and useful method to preserve olfactory function during A-com aneurysm surgery. 8).

For Aydin et al. the functions of olfactory nerve could be preserved at a relatively high rate of 85 per cent. This high rate resulted from the microtechnique employed as well as the relatively cautious frontal lobe retraction which was less than 1.5 cm 9).

For Fujiwara et al. Unilateral dural incision and unilateral brain retraction without elevation of the frontal lobe from the frontal base are important, because frontal lobe depression and elevation during surgery may injure the olfactory nerve 10).

Outcome

Olfactory dysfunction has an important impact on quality of life. Recovery after traumatic anosmia has been recorded up to 5 years after injury. Nevertheless, the authors believe that the damage is permanent when lasting 35 months or longer 11).

Case series

The interhemispheric approach (IHA) provides an excellent surgical corridor for clipping anterior communicating artery aneurysms (AcoAAs). However, an important disadvantage of the approach is obtaining proximal control at A1 in the last stage of dissection, especially in anterior or superior projecting AcoAAs and ruptured cases. Wongsuriyanan and Sriamornrattanakul described and evaluated the microsurgical clipping of AcoAAs using the IHA with early A1 exposure.

This was a retrospective descriptive study in patients with AcoAA who received microsurgical clipping through the IHA with early A1 exposure between April 2016 and May 2019. Aneurysm morphology, projection, completeness of clipping, surgical complications, and outcomes were collected from medical records.

Twenty-five patients with AcoAA received microsurgical clipping via the IHA with early A1 exposure. Twenty-three patients (92%) presented with subarachnoid hemorrhage. Intraoperative rupture while dissecting the interhemispheric fissure occurred in 2 cases, for which proximal control via subfrontal route was effectively performed. Of the patients, 100% achieved complete obliteration of their aneurysms. Postoperative anosmia was detected in 22.7%. In ruptured cases, 16 (88.9%) of the good grade patients achieved a good outcome (Glasgow Outcome Scale scores of 4 and 5) at 3 months after the operation.

The IHA with early A1 is safe and effective for clipping AcoAAs. 12).

Hendrix et al. assessed the risk for olfactory dysfunction following surgical treatment of unruptured cerebral aneurysm via the supraorbital minicraniotomy. A retrospective review of patients with electively treated cerebral aneurysms who underwent perioperative assessment of olfactory function using a sniffin’ sticks odor identification test between January 2015 and January 2016 was performed. A subgroup of patients without history of subarachnoid hemorrhage, without prior intracranial aneurysm treatment, and confirmed olfactory function underwent supraorbital keyhole craniotomy for aneurysm clipping. Microscopic and endoscopic videos were reviewed for this subgroup. Sixty-four patients who underwent elective aneurysm treatment either via surgical clipping or endovascular aneurysm obliteration were identified. Prior to treatment, 4/64 (6.3%) demonstrated bilateral anosmia. Collectively, 14 patients (21.9%) met subgroup criteria of supraorbital keyhole craniotomy for aneurysm clipping. Here, olfactory performance significantly decreased postoperatively on the side of craniotomy (ipsilateral, P = 0.007), whereas contralateral and bilateral olfactory function remained unaltered (P = 0.301 and P = 0.582, respectively). Consequently, 4/14 patients (28.6%) demonstrated ipsilateral anosmia 3 months after surgery. One patient (1/14, 7.1%) also experienced contralateral anosmia resulting in bilateral anosmia. Intraoperative visualization of the olfactory tract and surgical maneuvers do not facilitate prediction of olfactory outcome. The supraorbital keyhole craniotomy harbors a specific risk for unilateral olfactory deterioration. Lack of perioperative olfactory assessment likely results in underestimation of the risk for olfactory decline. Despite uneventful surgery, prediction of postoperative olfactory function and dysfunction remain challenging 13).

A total of 63 patients (aged 41-79 yr, mean 64 yr) with relatively small AcomA aneurysms clipped via the lateral supraorbital approach were retrospectively analyzed among the 105 AcomA aneurysms treated by clipping from 2005 to 2014. Neurological and cognitive functions were examined by several scales, including the modified Rankin Scale (mRS) and Mini-Mental Status Examination. The depressive state was assessed using the Beck Depression Inventory and Hamilton Depression Scale. The state of clipping was assessed 1 yr and then every few years after the operation by 3-dimensional computed tomography angiography.

Complete aneurysm neck clipping was confirmed in 62 aneurysms (98.4%). Perioperative complications occurred in 5 patients (5/63; mild frontalis muscle weakness in 3, anosmia in 1, and meningitis in 1). The mean clinical follow-up period was 5.2 ± 2.1 yr. No patient showed an mRS score more than 2 and all were completely independent in daily life. The depression scores were significantly improved after surgery. The overall mortality was 0% and overall morbidity (mRS score > 2 or Mini-Mental Status Examination score < 24) was 1.6%. All completely clipped aneurysms did not show any recurrence during the mean follow-up period of 4.9 ± 2.1 yr.

Keyhole Lateral supraorbital approach to clip relatively small unruptured AcomA aneurysm promises less invasive and durable treatment 14).

Cho et al. retrospectively reviewed the medical records of patients who underwent surgical clipping for unruptured aneurysm from 2011-2013 by the same senior attending physician. Since March 2012, olfactory protection using gelfoam and fibrin glue was applied in A-com aneurysm surgery. Therefore we categorized patients in two groups from this time-protected group and unprotected group.

Of the 63 enrolled patients, 16 patients showed postoperative olfactory dysfunction-including 8 anosmia patients (protected group : unprotected group=1 : 7) and 8 hyposmia patients (protected group : unprotected group=2 : 6). Thirty five patients who received olfactory protection during surgery showed a lower rate of anosmia (p=0.037, OR 10.516, 95% CI 1.159-95.449) and olfactory dysfunction (p=0.003, OR 8.693, 95% CI 2.138-35.356). Superior direction of the aneurysm was also associated with a risk of olfactory dysfunction (p=0.015, OR 5.535, 95% CI 1.390-22.039).

Superior direction of aneurysm appears associated with postoperative olfactory dysfunction. Olfactory protection using gelfoam and fibrin glue could be a simple, safe, and useful method to preserve olfactory function during A-com aneurysm surgery. 15).

The highest incidence of olfactory dysfunction following a pterional approach and its modifications for an intracranial aneurysm has been reported in cases of anterior communicating artery (ACoA) aneurysms. The radiological characteristics of unruptured ACoA aneurysms affecting the extent of retraction of the frontal lobe and olfactory nerve were investigated as risk factors for postoperative olfactory dysfunction.

Methods: A total of 102 patients who underwent a pterional or superciliary keyhole approach to clip an unruptured ACoA aneurysm from 2006 to 2013 were included in this study. Those patients who complained of permanent olfactory dysfunction after their aneurysm surgery, during a postoperative office visit or a telephone interview, were invited to undergo an olfactory test, the Korean version of the Sniffin’ Sticks test. In addition, the angiographic characteristics of ACoA aneurysms, including the maximum diameter, the projecting direction of the aneurysm, and the height of the neck of the aneurysm, were all recorded based on digital subtraction angiography and sagittal brain images reconstructed using CT angiography. Furthermore, the extent of the brain retraction was estimated based on the height of the ACoA aneurysm neck.

Results: Eleven patients (10.8%) exhibited objective olfactory dysfunction in the Sniffin’ Sticks test, among whom 9 were anosmic and 2 were hyposmic. Univariate and multivariate analyses revealed that the direction of the ACoA aneurysm, ACoA aneurysm neck height, and estimated extent of brain retraction were statistically significant risk factors for postoperative olfactory dysfunction. Based on a receiver operating characteristic (ROC) analysis, an ACoA aneurysm neck height > 9 mm and estimated brain retraction > 12 mm were chosen as the optimal cutoff values for differentiating anosmic/hyposmic from normosmic patients. The values for the area under the ROC curves were 0.939 and 0.961, respectively.

Conclusions: In cases of unruptured ACoA aneurysm surgery, the height of the aneurysm neck and the estimated extent of brain retraction were both found to be powerful predictors of the occurrence of postoperative olfactory dysfunction. 16).

Matano et al. presented a fibrin-gelatin fixation method that provides reinforcement and moisture to help preserve the olfactory nerve when using the anterior interhemispheric approach and describe the results and outcomes of this technique. We analyze the outcomes with this technique in 45 patients who undergo surgery for aneurysms, brain tumors, or other pathologies via the anterior interhemispheric approach. Anosmia occurred in 4 patients (8.8%); it was transient in 2 (4.4%) and permanent in the remaining 2 (4.4%). Brain tumors clearly attached to the olfactory nerve were resected in the patients with permanent anosmia. We found a significant difference in the presence of anosmia between patients with or without lesions that were attaching the olfactory nerve (p = 0.011). Our results suggested that fibrin-gelatin fixation method can reduce the reported risk of anosmia. However, the possibility of olfactory nerve damage is relatively high when operating on brain tumors attaching olfactory nerve 17).

Lai et al. presented the operative experiences in a consecutive series of 103 patients with 115 unruptured AcomA aneurysms. Clinical results, operative complications, angiographic outcomes and prognostic factors associated with surgery are presented. Of the 115 aneurysm repairs attempted, 114 were treated by clipping or excision and suture. One aneurysm, less than 2mm, was wrapped. Six patients (5.8%; 95% confidence interval [CI], 2.5-12.4) experienced a new permanent neurological deficit. There was no postoperative mortality. Transient morbidity occurred in 11 patients (10.7%; 95% CI, 5.9-18.3), including transient anosmia (four patients), acute postoperative confusion and memory disturbances (four patients), extradural haematoma requiring surgery (two patients) and cerebrospinal fluid rhinorrhea (one patient). Of the 84 aneurysms (73.0%) that had documented postoperative angiography, 82 (97.6%) had complete obliteration of the aneurysm and two (2.4%) had neck remnants (mean angiographic follow-up 28.0 months; range, 1.6-146.4 months). Retreatment was performed in one patient (1.0%). Logistic regression analysis of risk factors revealed that aneurysm size (p<0.01) was a significant predictor of outcome. There was no incidence of subarachnoid haemorrhage in the 272 person years of follow-up. In the current study, surgical treatment of unruptured AcomA aneurysms resulted in 5.8% morbidity and no mortality. The robustness of aneurysm repair achieved by open microsurgery is an important consideration when considering the option between endovascular and microsurgical treatment for unruptured AcomA aneurysms. 18).

Nakayama et al. studied the incidence of postoperative infection related to CSF leakage and anosmia in basal interhemispheric approach (BIH). Between April, 1990 to March, 2009, 142 cases of anterior communicating (Acom) aneurysm including both unruptured and ruptured have been treated by clipping surgery using BIH. We retrospectively obtained clinical informations from medical records and video records about infectious complications, CSF leakage of cerebrospinal fluid (CSF), olfactory dysfunction and intraoperative findings of damage to the olfactory nerve. In most cases (139 patients, 97%), frontal sinus were opened at craniotomy. Of all, CSF rinorrhea occurred in 4 cases (2.8%), and meningitis in 6 cases. There was only one patient who sufferd from meningitis due to CSF rinorrhea. All that patients recovered completely without deficit. Anosmia occurred in 6 cases (4.2%), and intraoperative injuries in 4 cases (2.8%). There was only one patient in whom anosmia was consistent with nerve injury. In conclusion, BIH is an appropriate procedure for infection risk control in Acom aneurysm surgery. It is difficult to avoid olfactory dysfunction completely, even if olfactory nerves are preserved in form. 19).

The horizontal head position was adopted in the unilateral anterior interhemispheric approach to treat an anterior communicating artery (ACoA) aneurysm. The patient was placed in the supine position. The patient’s head was rotated to the right to orient the midline horizontally, and tilted 45 degrees superiorly. After bicoronal skin incision and bifrontal craniotomy, the dura on the right side (downside) was opened. Dissection of the right interhemispheric fissure allowed gravity to retract the right (downside) hemisphere, which fell away from the falx, while the falx supported the upside hemisphere. The present approach was used in three patients with ACoA aneurysm between January 2009 and April 2010. The aneurysms were adequately clipped with this approach. No complication related to the approach occurred. No patients exhibited anosmia after surgery. This approach is useful for ACoA aneurysms. 20).

Beseoglu et al. in 2003 introduced a minimally invasive transorbital keyhole approach. Because this approach requires removal of the orbital rim and orbital roof, there have been concerns regarding perioperative morbidity, long-term morbidity, and cosmetic results. The authors evaluated approach-related morbidity and cosmetic results in their patients to determine the rate of complications and compared this to published reports of similar approaches.

Material: Seventy-one patients (41 female, 30 male) underwent operations using this approach between 2004 and 2008. Immediate approach-related morbidity was recorded after the operation. Late morbidity was determined after 7 months by an independent examiner while cosmetic results were self-rated by the patient using a questionnaire.

Results: Fifty-one (72%) of 71 patients had no postoperative complications and 12 (16.9%) had minor complications, the most common of which was subgaleal CSF collection (7.0%). Other minor complications included facial nerve palsy (2.8%), hyposphagma (2.8%), periorbital swelling due to periorbital hematoma (2.8%), and subdural hematoma (1.4%). Major complications requiring surgical revision occurred in 4 patients (5.6%); these were CSF fistulas in 2 patients, pneumocephalus in 1 patient, and a hematoma in 1 patient. Forty-nine (90.7%) of all 54 examined patients rated the cosmetic results as very good or good. Major long-term morbidity was hyposmia or anosmia (14 patients) followed by hypoesthesia around the scar (9 patients).

The transorbital keyhole approach is a feasible approach with a low-risk profile for postoperative or long-term morbidity and excellent cosmetic outcome 21)

Although the frequency of smell disorders after the operations of the anterior communicating artery aneurysm depends to a large degree on the used surgical approach, several independent of surgery factors may contribute to the postoperative smell tests outcome. THE AIM OF OUR STUDIES: The evaluation of the sense of smell in patients who underwent the operation of ruptured anterior communicating artery aneurysm using pterional approach.

Material and methods: In the retrospective studies the results of smell test of the group of 21 patients operated for ruptured anterior communicating artery aneurysm and 21 healthy volunteers of control group were compared. The patients suffering from neurodegenerative, metabolic and endocrynological disorders, as well as those with rhinoscopic symptoms of rhinosinusitis and with decreased nasal potency confirmed by anterior rhinomanometry were excluded from the study.

Results: During the operations it was possible to anatomically retain olfactory nerves in all operated patients. Severe smell disorders (severe hyposmia and anosmia) were detected in 1 (4.7%) patient of the control group and in 6 (28.5%) patients of postoperative group. The mean composite olfactory score in Cain test of the postoperative group was 4.53, and in the control group 5.47 points. The difference did not reach statistic significance (Mann-Whitney test, p = 0.068).

Conclusions: Although pterional approach to anterior communicating artery is relatively low traumatic to olfactory tract, the subarachnoid hemorrhage may have an unfavorable effect on postoperative olfactory nerve functioning. Considering the fact, that in spite of thorough examination of the patients, we were not able to exclude from the studied groups all the patients with preoperatively impaired smell, it seems reasonable to perform similar smell test studies in the prospective way 22).

Bor et al. interviewed all patients who resumed independent living after SAH treated with coiling between 1997 and 2007. We assessed by means of logistic regression analyses whether risk of anosmia was influenced by site of the ruptured aneurysm, neurological condition on admission, amount of extravasated blood, hydrocephalus, and treatment for hydrocephalus.

Of 197 patients, 35 (18%; 95%CI:12 to 23) experienced anosmia. Anosmia had improved in 23 (66%) of them; in 20 the recovery had been complete after a median period of 6 weeks (SD +/-6.5). Intraventricular hemorrhage was a risk factor for anosmia (OR 2.4; 95%CI:1.0 to 5.9). Anterior aneurysm location (OR 1.1; 95%CI:0.5 to 2.3) and high amount of extravasated blood (OR 0.9; 95%CI:0.4 to 2.1) were not related to anosmia.

Anosmia occurs after coiling in 1 of every 6 SAH patients, but has a good prognosis in most patients. The cause of anosmia after coiling for ruptured aneurysms remains elusive; severity of the initial hemorrhage or long lasting hydrocephalus may be contributing factors. 23).

Martin et al. studied whether and how frequently patients with ACoA aneurysms present with smell identification deficits in 2 treatment groups (endovascular and surgical treatment).

Methods: A prospective study was conducted of patients with SAH caused by ruptured ACoAs and who had a Glasgow Outcome Scale score of 1 or 2, in comparison with a control group matched by age and sex. Olfactory function was assessed using the University of Pennsylvania Smell Identification Test (UPSIT).

Results: A total of 39 patients were enrolled. A marked olfactory impairment was observed in patients with ruptured ACoAs compared with the control group (p < 0.001). Seventeen patients with ruptured ACoAs (44%) compared with 1 patient in the control group (3%) showed a smell identification deficit according to performance on the UPSIT (p < 0.001). Both groups that underwent treatment presented with olfactory impairment. Ten (59%) of 17 patients who underwent aneurysmal clip placement versus 6 (28.5%) of 21 patients who underwent coil embolization scored below the 25th percentile on the UPSIT, and surgical patients also performed worse than endovascular patients (p = 0.048). The authors observed a worse performance on the olfactory test in patients subjected to endovascular coil embolization when cerebral vasospasm (p = 0.037) or frontal cerebral lesions (p = 0.009) were present. This difference was not observed in patients who underwent surgery.

Conclusions: Olfactory disorders after SAH caused by rupture of the ACoA are very frequent and were present in both treatment groups. Cerebral vasospasm and frontal lobe lesions are related to worse performance on an olfactory test in patients undergoing endovascular coil embolization 24).

To discriminate between the effects of aneurysmal rupture and treatment, Moman et al. assessed the occurrence of anosmia after clipping and coiling of unruptured aneurysms as well as after the coiling of ruptured aneurysms.

Methods: The authors interviewed patients in whom an unruptured aneurysm was treated by clipping (32 cases) or endovascular coiling (26 cases) as well as patients with SAH who underwent coil therapy (32 cases). A geographically defined subset of 20 patients per group was invited to undergo olfactory testing.

Results: Nine clip-treated patients (28% [95% CI 14-47%]) in the unruptured group reported having anosmia, and no coil-treated patient in the unruptured group (95% [CI 0-13%]) reported having anosmia; in the SAH group, 7 patients (22% [95% CI 9-40%]) reported having anosmia. Anosmia had improved over time in 3 of the clip-treated patients and in all but 1 of the patients with SAH. Examination revealed olfactory disturbance in 13 (65% [95% CI 41-85%]) of the clip-treated and 8 (42% [95% CI 20-67%]) of the coil-treated patients with unruptured aneurysms, and also in 7 (35% [95% CI 15-59%]) coil-treated patients with SAH. In 20 patients who underwent clip therapy for unruptured aneurysms, 19 (95% [95% CI 75-100%]) had olfactory dysfunction on the side ipsilateral to surgery (anosmia reported by 8 of them).

Conclusions: Both clip treatment and SAH contribute to the occurrence of anosmia, with different chances of improvement. Olfactory dysfunction occurs in almost all patients on the side of surgery and can occur subclinically after coil deployment. 25).

Wermer et al. studied the prevalence, predisposing factors (aneurysm site and type of treatment), impact, and prognosis of anosmia in patients with SAH.

Of the patients with SAH who resumed independent living, we included all patients treated by coiling between 1997 and 2003 and a sample of patients treated by clipping between 1985 and 2001. Patients underwent structured interviews regarding the presence and duration of anosmia. The impact of anosmia was scored using a visual analog scale ranging from 0 (no influence) to 100 (the worst thing that ever happened to them). Risk factors for anosmia were assessed by logistic regression analysis.

Overall, 89 of the 315 interviewed patients (28%; 95% confidence interval [CI], 23-34%) reported anosmia after SAH (mean follow-up period, 7.4 yr), including 10 (15%) of the 67 coiled patients and 79 (32%) of the 248 clipped patients. The median visual analog scale impact score was 53 (range, 0-100). In 20 of the 89 patients (23%; 95% CI, 15-33), the symptoms had improved over time. Risk factors for anosmia were treatment by clipping (odds ratio [OR], 2.7; 95% CI, 1.3-5.7) and anterior communicating artery aneurysms (OR, 2.0; 95% CI, 1.2-3.3).

Anosmia after SAH has a high prevalence, considerable impact, and poor prognosis. Its occurrence after coiling suggests not only damage to the olfactory nerve by clipping but also that the SAH itself plays a role in its pathogenesis. 26)

Nozaki et al. described a patient with bilateral persistent primitive olfactory arteries associated with an unruptured saccular aneurysm on the left persistent primitive olfactory artery. Seven reported cases with this anomalous artery including ours are reviewed and classified into two variants. This anomalous artery arises from the terminal portion of the internal carotid artery and courses anteromedially along the ipsilateral olfactory tract and makes a hair-pin curve posterior to the olfactory bulb, becoming the distal anterior cerebral artery (variant 1) or the ethmoidal artery (variant 2). Out of 7 reported cases, 4 cases are associated with saccular aneurysms. The aneurysm in variant 1 is located on the hair-pin curve at which an apparent arterial branch is sometimes absent. Two patients suffer from anosmia. Persistent primitive olfactory artery should be kept in mind because of its high association with intracranial saccular aneurysms and unique clinical presentation. 27).

In as retrospective study, 100 patients with anterior communicating artery aneurysms, for whom the pterional approach was employed, were observed from the point of view of postoperative olfactory nerve function. In the postoperative period only three cases suffered from the impaired sense of smell ipsilateral to the side of surgery. 15 patients objectively showed olfactory nerve distinctions. The functions of olfactory nerve could be preserved at a relatively high rate of 85 per cent. This high rate resulted from the microtechnique employed as well as the relatively cautious frontal lobe retraction which was less than 1.5 cm. 28).

Between 1969 and 1994 we treated 450 patients with ruptured anterior communicating artery aneurysms, of which 434 cases (96.4%) were operated on via the interhemispheric approach (IH), namely, until 1979 mainly, via bifrontal craniotomy, subfrontal and interhemispheric approach (SIH) and, since 1979, via posterior interhemispheric approach (PIH). Postoperative olfactory dysfunction is one of the main disadvantages of IH. The mechanisms and the incidence of this disadvantage were studied in both approaches. The causes of postoperative anosmia in SIH were as follows: sectioning of olfactory tracts intentionally or not, avulsion of olfactory bulbs and probability of ischemic or minor mechanical insults to olfactory tracts. However, these matters rarely occur in PIH because of little exposure of olfactory nerves. The mechanisms of postoperative anosmia in PIH were considered to be as follows: sinking of frontal lobes due to excessive drainage of cerebrospinal fluid and over-retraction of frontal lobes. The incidence of postoperative anosmia decreased from 27.0% via SIH to 5.5% via PIH 29).

The olfactory function could be examined in 101 of 138 patients with anterior communicating artery aneurysms, whom we treated during a recent 6-year period. Among them, 49 patients underwent surgery by the anterior interhemispheric approach and 52 underwent surgery by the basal interhemispheric approach. Fifteen patients (31%) exhibited anosmia after surgery by the anterior interhemispheric approach, whereas only one patient (1.9%) exhibited anosmia after surgery by the basal interhemispheric approach. Unilateral dural incision and unilateral brain retraction without elevation of the frontal lobe from the frontal base are important, because frontal lobe depression and elevation during surgery may injure the olfactory nerve 30).

Yasui et al. reviewed the surgical outcome in 85 patients with ruptured anterior communicating artery (ACoA) aneurysms, who were operated on within 72 hours of onset via a basal interhemispheric (BIH) approach (Group 1, N = 48), or an anterior interhemispheric (AIH) approach (Group 2, N = 37). The age, sex ratio and pre-operative grade (Gr) were similar for both groups. The outcome at the time of discharge was as follows for group 1: excellent or good 88%; fair, 6%; vegetative state, 2% and death 4%. For group 2, it was: excellent or good 78%; fair, 16%; vegetative state, 3%; and death, 3%. A significant correlation between admission grade and outcome was found in both groups. The outcome in group 1 was better than in group 2 for patients with a Glasgow Outcome Scale (GOS) better than fair (p < 0.07). No patient in group 1 had postoperative anosmia, but nine patients in group 2 became anosmic. The total number of complications was also significantly less in group 1. Our overall mortality rate was 4%. In conclusion, the BIH approach was more beneficial for treating acute ACoA aneurysm. 31).

In a retrospective study of 25 patients operated on for ruptured intracranial aneurysms via the frontotemporal route, 22 patients suffered postoperatively from anosmia ipsilateral to the side of surgery. This complication most often goes unrecognized by the patient as well as the physician, and attention should be drawn to it because of its widespread occurrence. This investigation demonstrates a high incidence of anosmia (24 (88.9%) of 27 surgical sides) occurring ipsilateral to the frontotemporal approach in aneurysm surgery. Recovery after traumatic anosmia has been recorded up to 5 years after injury. Nevertheless, the authors believe that the damage is permanent when lasting 35 months or longer 32)

References

1)

Bor AS, Niemansburg SL, Wermer MJ, Rinkel GJ. Anosmia after coiling of ruptured aneurysms: prevalence, prognosis, and risk factors. Stroke. 2009 Jun;40(6):2226-8. doi: 10.1161/STROKEAHA.108.539445. Epub 2009 Apr 16. PMID: 19372449.
2)

Martin GE, Junqué C, Juncadella M, Gabarrós A, de Miquel MA, Rubio F. Olfactory dysfunction after subarachnoid hemorrhage caused by ruptured aneurysms of the anterior communicating artery. Clinical article. J Neurosurg. 2009 Nov;111(5):958-62. doi: 10.3171/2008.11.JNS08827. PMID: 19361265.
3)

Moman MR, Verweij BH, Buwalda J, Rinkel GJ. Anosmia after endovascular and open surgical treatment of intracranial aneurysms. J Neurosurg. 2009 Mar;110(3):482-6. doi: 10.3171/2008.8.JNS08761. PMID: 19072311.
4)

Wermer MJ, Donswijk M, Greebe P, Verweij BH, Rinkel GJ. Anosmia after aneurysmal subarachnoid hemorrhage. Neurosurgery. 2007 Nov;61(5):918-22; discussion 922-3. doi: 10.1227/01.neu.0000303187.34308.7b. PMID: 18091268.
5) , 16)

Park J, Son W, Goh DH, Kang DH, Lee J, Shin IH. Height of aneurysm neck and estimated extent of brain retraction: powerful predictors of olfactory dysfunction after surgery for unruptured anterior communicating artery aneurysms. J Neurosurg. 2016 Mar;124(3):720-5. doi: 10.3171/2015.1.JNS141766. Epub 2015 Aug 14. PMID: 26274995.
6) , 12)

Wongsuriyanan S, Sriamornrattanakul K. Interhemispheric Approach with Early A1 Exposure for Clipping Anterior Communicating Artery Aneurysms: Operative Techniques and Outcomes. World Neurosurg. 2020 Jun;138:e579-e590. doi: 10.1016/j.wneu.2020.03.005. Epub 2020 Mar 9. PMID: 32165343.
7)

Ito S, Fujimoto S, Saito K, Tada H, Tanaka T. [Postoperative olfactory dysfunction in interhemispheric approach for ruptured anterior communicating artery aneurysms]. No Shinkei Geka. 1996 Jul;24(7):625-8. Japanese. PMID: 8752875.
8) , 15)

Cho H, Jo KI, Yeon JY, Hong SC, Kim JS. Feasibility and Efficacy of Olfactory Protection Using Gelfoam and Fibrin Glue during Anterior Communicating Artery Aneurysm Surgery. J Korean Neurosurg Soc. 2015 Aug;58(2):107-11. doi: 10.3340/jkns.2015.58.2.107. Epub 2015 Aug 28. PMID: 26361525; PMCID: PMC4564741.
9)

Aydin IH, Kadioğlu HH, Tüzün Y, Kayaoğlu CR, Takçi E, Oztürk M. Postoperative anosmia after anterior communicating artery aneurysms surgery by the pterional approach. Minim Invasive Neurosurg. 1996 Sep;39(3):71-3. doi: 10.1055/s-2008-1052220. PMID: 8892284.
10) , 30)

Fujiwara H, Yasui N, Nathal-Vera E, Suzuki A. Anosmia after anterior communicating artery aneurysm surgery: comparison between the anterior interhemispheric and basal interhemispheric approaches. Neurosurgery. 1996 Feb;38(2):325-8. doi: 10.1097/00006123-199602000-00017. PMID: 8869060.
11) , 32)

Eriksen KD, Bøge-Rasmussen T, Kruse-Larsen C. Anosmia following operation for cerebral aneurysms in the anterior circulation. J Neurosurg. 1990 Jun;72(6):864-5. doi: 10.3171/jns.1990.72.6.0864. PMID: 2338570.
13)

Hendrix P, Fischer G, Krug J, Linnebach AC, Simgen A, Griessenauer CJ, Burkhardt BW, Oertel J. Olfactory dysfunction in patients undergoing supraorbital keyhole craniotomy for clipping of unruptured aneurysms. Clin Anat. 2020 Mar;33(2):316-323. doi: 10.1002/ca.23529. Epub 2019 Dec 14. PMID: 31769083.
14)

Mori K, Wada K, Otani N, Tomiyama A, Toyooka T, Tomura S, Takeuchi S, Yamamoto T, Nakao Y, Arai H. Long-Term Neurological and Radiological Results of Consecutive 63 Unruptured Anterior Communicating Artery Aneurysms Clipped via Lateral Supraorbital Keyhole Minicraniotomy. Oper Neurosurg (Hagerstown). 2018 Feb 1;14(2):95-103. doi: 10.1093/ons/opx244. PMID: 29228382.
17)

Matano F, Murai Y, Mizunari T, Tateyama K, Kobayashi S, Adachi K, Kamiyama H, Morita A, Teramoto A. Olfactory preservation during anterior interhemispheric approach for anterior skull base lesions: technical note. Neurosurg Rev. 2016 Jan;39(1):63-8; discussion 69. doi: 10.1007/s10143-015-0647-x. Epub 2015 Jul 17. PMID: 26178238.
18)

Lai LT, Gragnaniello C, Morgan MK. Outcomes for a case series of unruptured anterior communicating artery aneurysm surgery. J Clin Neurosci. 2013 Dec;20(12):1688-92. doi: 10.1016/j.jocn.2013.02.015. Epub 2013 Aug 16. PMID: 23958481.
19)

Nakayama H, Ishikawa T, Yamashita S, Fukui I, Mutoh T, Hikichi K, Yoshioka S, Kawai H, Tamakawa N, Moroi J, Suzuki A, Yasui N. [CSF leakage and anosmia in aneurysm clipping of anterior communicating artery by basal interhemispheric approach]. No Shinkei Geka. 2011 Mar;39(3):263-8. Japanese. PMID: 21372335.
20)

Hayashi N, Sato H, Akioka N, Kurosaki K, Hori S, Endo S. Unilateral anterior interhemispheric approach for anterior communicating artery aneurysms with horizontal head position–technical note. Neurol Med Chir (Tokyo). 2011;51(2):160-3. doi: 10.2176/nmc.51.160. PMID: 21358165.
21)

Beseoglu K, Lodes S, Stummer W, Steiger HJ, Hänggi D. The transorbital keyhole approach: early and long-term outcome analysis of approach-related morbidity and cosmetic results. Technical note. J Neurosurg. 2011 Mar;114(3):852-6. doi: 10.3171/2010.9.JNS1095. Epub 2010 Oct 29. PMID: 21029037.
22)

Sieśkiewicz A, Kochanowicz J, Rutkowska J, Rogowski M, Olszewska E. Ocena zaburzeń wechu u chorych po operacji peknietego tetniaka tetnicy łaczacej przedniej mózgu [The evaluation of olfactory dysfunction after the operation of ruptured anterior communicating artery aneurysm]. Pol Merkur Lekarski. 2009 Oct;27(160):302-4. Polish. PMID: 19928658.
23)

Bor AS, Niemansburg SL, Wermer MJ, Rinkel GJ. Anosmia after coiling of ruptured aneurysms: prevalence, prognosis, and risk factors. Stroke. 2009 Jun;40(6):2226-8. doi: 10.1161/STROKEAHA.108.539445. Epub 2009 Apr 16. PMID: 19372449.
24)

Martin GE, Junqué C, Juncadella M, Gabarrós A, de Miquel MA, Rubio F. Olfactory dysfunction after subarachnoid hemorrhage caused by ruptured aneurysms of the anterior communicating artery. Clinical article. J Neurosurg. 2009 Nov;111(5):958-62. doi: 10.3171/2008.11.JNS08827. PMID: 19361265.
25)

Moman MR, Verweij BH, Buwalda J, Rinkel GJ. Anosmia after endovascular and open surgical treatment of intracranial aneurysms. J Neurosurg. 2009 Mar;110(3):482-6. doi: 10.3171/2008.8.JNS08761. PMID: 19072311.
26)

Wermer MJ, Donswijk M, Greebe P, Verweij BH, Rinkel GJ. Anosmia after aneurysmal subarachnoid hemorrhage. Neurosurgery. 2007 Nov;61(5):918-22; discussion 922-3. doi: 10.1227/01.neu.0000303187.34308.7b. PMID: 18091268.
27)

Nozaki K, Taki W, Kawakami O, Hashimoto N. Cerebral aneurysm associated with persistent primitive olfactory artery aneurysm. Acta Neurochir (Wien). 1998;140(4):397-401; discussion 401-2. doi: 10.1007/s007010050114. PMID: 9689332.
28)

Aydin IH, Kadioğlu HH, Tüzün Y, Kayaoğlu CR, Takçi E, Oztürk M. Postoperative anosmia after anterior communicating artery aneurysms surgery by the pterional approach. Minim Invasive Neurosurg. 1996 Sep;39(3):71-3. doi: 10.1055/s-2008-1052220. PMID: 8892284.
29)

Ito S, Fujimoto S, Saito K, Tada H, Tanaka T. [Postoperative olfactory dysfunction in interhemispheric approach for ruptured anterior communicating artery aneurysms]. No Shinkei Geka. 1996 Jul;24(7):625-8. Japanese. PMID: 8752875.
31)

Yasui N, Nathal E, Fujiwara H, Suzuki A. The basal interhemispheric approach for acute anterior communicating aneurysms. Acta Neurochir (Wien). 1992;118(3-4):91-7. doi: 10.1007/BF01401292. PMID: 1456108.

Anterior cervical discectomy

Anterior cervical discectomy

The most common surgical techniques are cervical discectomy with or without fusing the two adjacent intervertebral bodies. Robinson and Smith 1) 2) 3) 4). introduced the anterior cervical decompression technique without microscope, but with fusion by inserting a bone graft harvested from the iliac crest of the patient.

Hankinson and Wilson 5) improved the procedure with the use of an operating microscope; however, they performed the surgery without leaving a graft behind; the results of both types of surgery were entirely comparable 6) 7) 8).

In time several modifications of these surgical techniques have been made 9) 10) 11).

Anterior

Surgical decompression for cervical radiculopathy includes:

1.- Anterior cervical discectomy without any prosthesis or fusion: rarely used today.

2.- Anterior cervical discectomy and fusion with interbody fusion: the most common approach.

a.- without anterior cervical plate.

b.- with anterior cervical plate or with zero profile.

3.- with artificial disc: see Cervical disc arthroplasty

4.- Percutaneous

a.- Anterior percutaneous cervical disc chemonucleolysis.

Tissue trauma is significantly reduced with laser and endoscopic surgery techniques. Anterior cervical laser discectomy and Anterior percutaneous endoscopic cervical discectomy are both suitable for the specific indication of soft, symptomatic contained cervical disc herniations. A prospective cohort study indicates that Anterior cervical laser discectomy and Anterior percutaneous endoscopic cervical discectomy are options for cervical decompression surgery when medical comorbidities or preferences by patients and surgeons dictate more minimally invasive strategies 12).

Technique

see Anterior cervical discectomy technique

Complications

see Anterior cervical discectomy complications.

Outcome

see Anterior cervical discectomy outcome.

Case series

see Anterior cervical discectomy case series.

References

1)

Aronson N, Filtzer Dl, Bugan M. Anterior cervical fusion by the Smith–Robinson approach. J Neurosurg. 1968;29:397–404.
2)

Robinson RA, Smith GW. Anterolateral cervical disc removal and interbody fusion for cervical disc syndrome. Bull John Hopkins Hosp. 1955;96(Suppl):223–224.
3)

Robinson RA. Anterior and posterior cervical spine fusions. Clin Orthop Relat Res. 1964 Jul-Aug;35:34-62. PubMed PMID: 5889170.
4)

SMITH GW, ROBINSON RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am. 1958 Jun;40-A(3):607-24. PubMed PMID: 13539086.
5)

Hankinson HL, Wilson CB. Use of the operating microscope in anterior cervical discectomy without fusion. J Neurosurg. 1975 Oct;43(4):452-6. PubMed PMID: 1159482.
6)

Abd-Alrahman N, Dokmak AS, Abou-Madawi A. Anterior cervical discectomy (ACD) versus anterior cervical fusion (ACF), clinical and radiological outcome study. Acta Neurochir (Wien). 1999;141(10):1089-92. PubMed PMID: 10550654.
7)

Dowd GC, Wirth FP. Anterior cervical discectomy: is fusion necessary? J Neurosurg. 1999 Jan;90(1 Suppl):8-12. PubMed PMID: 10413119.
8)

Jacobs WC, Anderson PG, Limbeek J, Willems PC, Pavlov P. Single or double-level anterior interbody fusion techniques for cervical degenerative disc disease. Cochrane Database Syst Rev. 2004 Oct 18;(4):CD004958. Review. Update in: Cochrane Database Syst Rev. 2011;(1):CD004958. PubMed PMID: 15495130.
9)

Baskin DS, Ryan P, Sonntag V, Westmark R, Widmayer MA. A prospective, randomized, controlled cervical fusion study using recombinant human bone morphogenetic protein-2 with the CORNERSTONE-SR allograft ring and the ATLANTIS anterior cervical plate. Spine (Phila Pa 1976). 2003 Jun 15;28(12):1219-24; discussion 1225. PubMed PMID: 12811263.
10)

CLOWARD RB. The anterior approach for removal of ruptured cervical disks. J Neurosurg. 1958 Nov;15(6):602-17. PubMed PMID: 13599052.
11)

Madawi AA, Powell M, Crockard HA. Biocompatible osteoconductive polymer versus iliac graft. A prospective comparative study for the evaluation of fusion pattern after anterior cervical discectomy. Spine (Phila Pa 1976). 1996 Sep 15;21(18):2123-9; discussion 2129-30. PubMed PMID: 8893437.
12)

Hellinger S, Knight M, Telfeian AE, Lewandrowski KU. Patient selection criteria for percutaneous anterior cervical laser versus endoscopic discectomy. Lasers Surg Med. 2022 Jan 6. doi: 10.1002/lsm.23514. Epub ahead of print. PMID: 34989414.

Anterior communicating artery aneurysm endovascular treatment

Anterior communicating artery aneurysm endovascular treatment

Endovascular treatment has been increasingly performed due to the fact that it is less likely to cause high dysfunction compared to surgery and the treatment has been improved. The International Subarachnoid Aneurysm Trial reported anterior communicating artery aneurysms to comprise 45.4% of cerebral aneurysms on which both endovascular treatment and surgery are suitable. The use of the endovascular treatment for anterior communicating artery aneurysms is expected to increase in the future 1).

With regard to the endovascular technique, firstly, many Anterior communicating artery aneurysm (AcoA aneurysms) have very small sacs, which makes it difficult to distinguish between the aneurysm neck and the microcatheter selection, leading to a few disadvantages.

The standard coil embolization technique is limited by its inability to occlude wide necked aneurysms. Stent deployment across the aneurysm neck supports the coil mass inside the aneurysmal sac, and furthermore, has an effect on local hemodynamic and biologic changes

In the cases of Choi et al., 17 of 112 aneurysms (15%) had very small sacs, and 15 of these patients (88%) were treated with surgical clipping 2).

The second disadvantage of endovascular treatment for AcoA aneurysms is poor controllability and track-ability due to arterial morphology and the acute angle during the endovascular procedure. Moret et al., 3) reported that the main causes of failure to embolize were loops in the cervical and intracranial vessels despite using the cervical approach when necessary and acute angle changes of the posterior projection of the aneurysm 4).

Furthermore, the lumen of the AcoA is relatively small, and remodeling neck techniques using balloons or stents is particularly difficult when treating wide neck or complex aneurysms Safe and complete endovascular occlusion of these aneurysms usually requires the assistance of combined approaches using balloons and stents in an individually tailored strategy 5).

The treatment modality of AcoA aneurysms is affected more by anatomic factors than other aneurysms. However, optimal treatment for AcoA aneurysms cannot be determined by any one anatomic characteristic; rather, all of the morphological features and clinical factors must be considered.

Many papers have emphasized the need for a collaborative approach to treatment strategies and have shown varying tendencies toward coiling or clipping 6)

The decision-making process during recent years has become increasingly more based on collaboration. All patient cases are discussed by a team including at least one endovascular specialist, one neurosurgeon, and one neurologist. Those presenting acutely are always routinely reviewed by both a surgeon and an endovascular radiologist.

In the study of Choi et al., correlated 5 clinical factors and 5 anatomical factors related to determining treatment modality with clinical and anatomical outcomes. Of the 5 clinical factors, age was the important factor in both uni and multivariate analysis. Older patients (age, >65 years) had significantly higher odds of being treated with coil embolization vs. clipping (adjusted OR, 3.78; 95% CI, 1.39-10.3; p=0.0093). The anatomical factors that affected initial treatment modality decision included aneurysm size (small or large vs. medium), neck size (<4 vs. ≥4) dome-to-neck ratio (<2 vs. ≥2), vessel incorporation, multiple lobulation, and morphologic score. Among these 5 anatomical factors, small or large size, dome-to-neck ratio <2, vessel incorporation, and morphologic score ≥2 were statistically significant in univariate analysis. In multivariate analysis, only morphologic score was statistically significant.

Patients with more than 2 unfavorable factors were treated with surgical clipping 4.34 times more often than with coil embolization. Furthermore, higher scoring patients had a higher tendency to be treated with surgical clipping

Balloon remodeling

Balloon remodeling should be considered for broad-based complex ACoA aneurysms. This technique provides a high rate of aneurysm occlusion with an acceptable complication profile, and avoids the need for dual antiplatelet therapy. The balloon trajectory will depend on aneurysm morphology and bilateral access may be useful in selected cases 7).

Complications

Intraprocedural aneurysm rupture and thrombus formation are serious complications during coiling of ruptured intracranial aneurysms, and they more often occur in patients with anterior communicating artery aneurysms.

Prolonged anterograde amnesia and disorientation after anterior communicating artery aneurysm coil embolization 8)

1)

Takeuchi M, Uyama A, Matsumoto T, Tsuto K. Endovascular Treatment for Anterior Communicating Artery Aneurysms. Adv Tech Stand Neurosurg. 2022;44:239-249. doi: 10.1007/978-3-030-87649-4_13. PMID: 35107683.
2)

Choi JH, Kang MJ, Huh JT. Influence of clinical and anatomic features on treatment decisions for anterior communicating artery aneurysms. J Korean Neurosurg Soc. 2011 Aug;50(2):81-8. doi: 10.3340/jkns.2011.50.2.81. Epub 2011 Aug 31. PubMed PMID: 22053224; PubMed Central PMCID: PMC3206283.
3)

Moret J, Pierot L, Boulin A, Castaings L, Rey A. Endovascular treatment of anterior communicating artery aneurysms using Guglielmi detachable coils. Neuroradiology. 1996;38:800–805.
4)

Proust F, Debono B, Hannequin D, Gerardin E, Clavier E, Langlois O, et al. Treatment of anterior communicating artery aneurysms : complementary aspects of microsurgical and endovascular procedures. J Neurosurg. 2003;99:3–14.
5)

Cohen JE, Melamed I, Itshayek E. X-microstenting and transmesh coiling in the management of wide-necked tent-like anterior communicating artery aneurysms. J Clin Neurosci. 2013 Nov 28. pii: S0967-5868(13)00496-7. doi: 10.1016/j.jocn.2013.09.003. [Epub ahead of print] PubMed PMID: 24291480.
6)

Cowan JA, Jr, Ziewacz J, Dimick JB, Upchurch GR, Jr, Thompson BG. Use of endovascular coil embolization and surgical clip occlusion for cerebral artery aneurysms. J Neurosurg. 2007;107:530–535.
7)

Moon K, Albuquerque FC, Ducruet AF, Crowley RW, McDougall CG. Balloon remodeling of complex anterior communicating artery aneurysms: technical considerations and complications. J Neurointerv Surg. 2014 Apr 28. doi: 10.1136/neurintsurg-2014-011147. [Epub ahead of print] PubMed PMID: 24778138.
8)

Al-Atrache Z, Friedler B, Shaikh HA, Kavi T. Prolonged anterograde amnesia and disorientation after anterior communicating artery aneurysm coil embolisation. BMJ Case Rep. 2019 Jul 30;12(7). pii: e230543. doi: 10.1136/bcr-2019-230543. PubMed PMID: 31366616.

Anterior Thalamic Stimulation

Anterior Thalamic Stimulation

Deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS) is a novel and promising treatment method for patients with drug-resistant epilepsy.

Clinical efficacy

More than 70% of patients implanted with ANT-DBS benefit significantly from this method, i.e., they report seizure-reduction rates higher than 50%

The median percent seizure reduction from baseline at 1 year was 41%, and 69% at 5 years. The responder rate (≥50% reduction in seizure frequency) at 1 year was 43%, and 68% at 5 years. In the 5 years of follow-up, 16% of subjects were seizure-free for at least 6 months. There were no reported unanticipated adverse device effects or symptomatic intracranial hemorrhages. The Liverpool Seizure Severity Scale and 31-item Quality of Life in Epilepsy measure showed statistically significant improvement over baseline by 1 year and at 5 years (p < 0.001).

Long-term follow-up of ANT deep brain stimulation showed sustained efficacy and safety in a treatment-resistant population.

Classification of evidence: This long-term follow-up provides Class IV evidence that for patients with drug-resistant partial epilepsy, anterior thalamic stimulation is associated with a 69% reduction in seizure frequency and a 34% serious device-related adverse event rate at 5 years. 1).

Adverse events

When focusing on the adverse events reported in a study of stimulation of the anterior nuclei of thalamus (SANTE study), the patients reported paresthesia (18% patients), pain in the implant side (10.9% patients), and infection at the implant site (9.1% patients) 2)

Literature search

Sobstyl et al. performed a literature search regarding the clinical efficacy of ANT DBS. They discussed the surgical technique of the implantation of DBS electrodes with special attention paid to the targeting methods of the ANT. Moreover, they present in detail the clinical efficacy of ANT DBS, with a special emphasis on the stimulation parameters, a stimulation mode, and polarity. They also report all adverse events and present the current limitations of ANT DBS.

In general, the safety profile of DBS in intractable epilepsy patients is good, with a low rate of surgery, hardware-related, and stimulation-induced adverse events. No significant cognitive declines or worsening of depressive symptoms was noted. At long-term follow-up, the quality-of-life scores have improved. The limitations of ANT DBS studies include a limited number of patients treated and mostly open-label designs with only one double-blind, randomized multicenter trial. Most studies do not report the etiology of intractable epilepsy or they include nonhomogeneous groups of patients affected by intractable epilepsy. There are no guidelines for setting initial stimulation parameters. All the variables mentioned may have a profound impact on the final outcome.

ANT DBS appears to be a safe and efficacious treatment, particularly in patients with refractory partial seizures (three-quarters of patients gained at least 50% seizure reduction after 5 years). ANT DBS reduces most effectively the seizures originating in the temporal and frontal lobes. The published results of ANT DBS highlight promise and hope for patients with intractable epilepsy 3).

A literature review discusses the rationale, mechanism of action, clinical efficacy, safety, and tolerability of ANT-DBS in drug-resistant epilepsy patients. A review using systematic methods of the available literature was performed using relevant databases including Medline, Embase, and the Cochrane Library pertaining to the different aspects ANT-DBS. ANT-DBS for drug-resistant epilepsy is a safe, effective and well-tolerated therapy, where a special emphasis must be given to monitoring and neuropsychological assessment of both depression and memory function. Three patterns of seizure control by ANT-DBS are recognized, of which a delayed stimulation effect may account for an improved long-term response rate. ANT-DBS remotely modulates neuronal network excitability through overriding pathological electrical activity, decrease neuronal cell loss, through immune response inhibition or modulation of neuronal energy metabolism. ANT-DBS is an efficacious treatment modality, even when curative procedures or lesser invasive neuromodulative techniques failed. When compared to VNS, ANT-DBS shows slightly superior treatment response, which urges for direct comparative trials. Based on the available evidence ANT-DBS and VNS therapies are currently both superior compared to non-invasive neuromodulation techniques such as t-VNS and rTMS. Additional in-vivo research is necessary in order to gain more insight into the mechanism of action of ANT-DBS in localization-related epilepsy which will allow for treatment optimization. Randomized clinical studies in search of the optimal target in well-defined epilepsy patient populations, will ultimately allow for optimal patient stratification when applying DBS for drug-resistant patients with epilepsy 4).

Case series

Bilateral ANT electrodes were implanted into 18 patients suffering from focal, pharmacoresistant epilepsy. Antiepileptic treatment was kept unchanged from three months prior to operation. The Liverpool seizure severity scale (LSSS) was used to measure the burden of epilepsy.

Results: There was no significant difference between the 2 groups at the end of the blinded period at 6 months. However, when considering all patients and comparing 6 months of stimulation with baseline, there was a significant, 22% reduction in the frequency of all seizures (P = 0.009). Four patients had ≥50% reduction in total seizure frequency and 5 patients ≥50% reduction in focal seizures after 6 months of stimulation. No increased effect over time was shown. LSSS at 6 months compared to baseline showed no significant difference between the 2 groups, but a small, significant reduction in LSSS was found when all patients had received stimulation for 6 months.

Conclusions: Our study supports results from earlier studies concerning DBS as a safe treatment option, with effects even in patients with severe, refractory epilepsy. However, our results are not as encouraging as those reported from many other, mainly unblinded, and open studies 5).

Case reports

A case of relapsing herpes simplex encephalitis (HSE) as a newly reported and potentially fatal stimulation-related adverse effect following stimulation of the anterior thalamic nucleus (ANT-DBS) accompanied by fever, confusion, and cognitive impairment in a 32-year-old epileptic patient with a history of herpes meningoencephalitis 31 years earlier. The T2-weighted/FLAIR high-signal intensity in the temporal lobe developed at a “distance” from the stimulation target. The positive polymerase chain reaction of herpes virus deoxyribonucleic acid in the cerebrospinal fluid confirmed the diagnosis. The condition improved partially on acyclovir and stimulation stopped. Seizures disappeared and then returned after few months. The unique case report presents a rationale for considering history of herpes encephalitis as a relative contraindication for ANT-DBS, and HSE relapse should be suspected in patients with post-stimulation fever and/or altered consciousness 6).

1)

Salanova V, Witt T, Worth R, Henry TR, Gross RE, Nazzaro JM, Labar D, Sperling MR, Sharan A, Sandok E, Handforth A, Stern JM, Chung S, Henderson JM, French J, Baltuch G, Rosenfeld WE, Garcia P, Barbaro NM, Fountain NB, Elias WJ, Goodman RR, Pollard JR, Tröster AI, Irwin CP, Lambrecht K, Graves N, Fisher R; SANTE Study Group. Long-term efficacy and safety of thalamic stimulation for drug-resistant partial epilepsy. Neurology. 2015 Mar 10;84(10):1017-25. doi: 10.1212/WNL.0000000000001334. Epub 2015 Feb 6. PMID: 25663221; PMCID: PMC4352097.
2)

Fisher R, Salanova V, Witt T, Worth R, Henry T, Gross R, Oommen K, Osorio I, Nazzaro J, Labar D, Kaplitt M, Sperling M, Sandok E, Neal J, Handforth A, Stern J, DeSalles A, Chung S, Shetter A, Bergen D, Bakay R, Henderson J, French J, Baltuch G, Rosenfeld W, Youkilis A, Marks W, Garcia P, Barbaro N, Fountain N, Bazil C, Goodman R, McKhann G, Babu Krishnamurthy K, Papavassiliou S, Epstein C, Pollard J, Tonder L, Grebin J, Coffey R, Graves N; SANTE Study Group. Electrical stimulation of the anterior nucleus of thalamus for treatment of refractory epilepsy. Epilepsia. 2010 May;51(5):899-908. doi: 10.1111/j.1528-1167.2010.02536.x. Epub 2010 Mar 17. PMID: 20331461.
3)

Sobstyl M, Stapińska-Syniec A, Iwański S, Rylski M. Clinical Efficacy and Safety Profile of Anterior Thalamic Stimulation for Intractable Epilepsy. J Neurol Surg A Cent Eur Neurosurg. 2021 Jun 14. doi: 10.1055/s-0041-1725954. Epub ahead of print. PMID: 34126641.
4)

Bouwens van der Vlis TAM, Schijns OEMG, Schaper FLWVJ, Hoogland G, Kubben P, Wagner L, Rouhl R, Temel Y, Ackermans L. Deep brain stimulation of the anterior nucleus of the thalamus for drug-resistant epilepsy. Neurosurg Rev. 2019 Jun;42(2):287-296. doi: 10.1007/s10143-017-0941-x. Epub 2018 Jan 6. PMID: 29306976; PMCID: PMC6502776.
5)

Herrman H, Egge A, Konglund AE, Ramm-Pettersen J, Dietrichs E, Taubøll E. Anterior thalamic deep brain stimulation in refractory epilepsy: A randomized, double-blinded study. Acta Neurol Scand. 2019 Mar;139(3):294-304. doi: 10.1111/ane.13047. Epub 2018 Dec 11. PMID: 30427061.
6)

Hamdi H, Robin E, Stahl JP, Doche E, Azulay JP, Chabardes S, Bartolomei F, Regis J. Anterior Thalamic Stimulation Induced Relapsing Encephalitis. Stereotact Funct Neurosurg. 2019;97(2):132-136. doi: 10.1159/000499072. Epub 2019 May 3. PMID: 31055582.