Operative Neurosurgery

Aneurysm clipping and Test

Aneurysm clipping

Latest PubMed Aneurysm clipping-related articles

Aneurysm clipping is a neurosurgical procedure performed to treat cerebral or intracranial aneurysms.

The purpose of intracranial aneurysm clipping is to prevent the aneurysm from rupturing by sealing it off from normal blood circulation. Here is an overview of the procedure:

Preoperative Evaluation: Before the surgery, a patient’s medical history and imaging studies, such as CT scans, MRI scans, or angiography, are thoroughly reviewed to determine the size, location, and characteristics of the aneurysm.

Anesthesia: The patient is placed under general anesthesia, rendering them unconscious and pain-free throughout the procedure.

Access to the Aneurysm: A neurosurgeon typically performs the surgery. They make an incision in the scalp to create a small opening in the skull, called a craniotomy, to access the brain and the aneurysm.

Clipping the Aneurysm: Once access is achieved, the surgeon carefully locates the aneurysm. A tiny metal clip is placed across the base of the aneurysm, effectively sealing it off from the surrounding blood vessels. This prevents blood from flowing into the aneurysm, reducing the risk of rupture.

Closure: After successfully clipping the aneurysm, the surgeon closes the incision in the scalp and may use surgical materials such as sutures, screws, or plates to secure the bone flap in place. The wound is then closed with stitches or staples.

Recovery: The patient is closely monitored in the intensive care unit (ICU) for a period to ensure stable vital signs and neurological function. Recovery times vary but can be several days to weeks depending on the complexity of the surgery and the patient’s overall health.

Intracranial aneurysm clipping is a highly effective treatment for preventing aneurysm rupture. However, it is a complex procedure with potential risks, including infection, bleeding, and damage to nearby structures in the brain. The choice of treatment, whether clipping or endovascular coiling (a less invasive procedure), depends on the specific characteristics of the aneurysm and the patient’s overall health.

Evolution in the surgical treatment of intracranial aneurysms is driven by the need to refine and innovate. From an early application of the Hunterian carotid ligation to modern-day sophisticated aneurysm clip designs, progress was made through dedication and technical maturation of the cerebrovascular neurosurgeons to overcome challenges in their practices. The global expansion of endovascular services has challenged the existence of aneurysm surgery, changing the complexity of aneurysm case mix and volume that are presently referred for surgical repair. Concepts of how to best treat intracranial aneurysms have evolved over generations, and will continue to do so with further technological innovations. As with the evolution of any type of surgery, innovations frequently arise from the criticism of currently available techniques 1).

Intracranial aneurysm surgery by clipping requires meticulous technique and is usually performed through open approaches. Endoscopic endonasal clipping of intracranial aneurysms may use the same techniques through an alternative corridor.

Clipping is an important technique for intracranial aneurysm surgery. Although clip mechanisms and features have been refined, little attention has been paid to clip appliers. Clip closure is traditionally achieved by opening the grip of the clip applier. Sato et al.. reconsidered this motion and identified an important drawback, namely that the standard applier holding power decreased at the moment of clip release, which could lead to unstable clip application develop a forceps to address this clip applier design flaw.The new clip applier has a non–cross-type fulcrum that is closed at the time of clip release, with an action similar to that of a bipolar forceps or scissors. Thus, a surgeon can steadily apply the clip from various angles. They successfully used the clip applier to treat 103 aneurysms. Although training was required to ensure smooth applier use, no difficulties associated with applier use were noted. This clip applier can improve clipping surgery safety because it offers additional stability during clip release. 2).

Indications

see Surgical clipping versus endovascular coiling for intracranial aneurysm.

Intracranial Aneurysm treatment with surgery remains the recommended form of treatment in high-grade SAH patients with intracerebral space occupying hematomas, where the surgical decompression of the mass effect may be warranted, and along with it the clipping of the bleeding aneurysm.

In the US, a number of training programs include endovascular exposure to residents during their training, assuming the endovascular suite as a regular OR room.

The training of surgeons in both techniques seems promising and the right way to go, regardless of whether a dually trained neurosurgeon will end up opting for the use of one technique over the other. The important is that we guarantee the ability to deliver our patients the best possible care by providing them with a choice that is not born out of a turf war but based on evidence both on a general, but similarly important, local one 3).

Preoperative planning

Three-dimensional printing in vascular neurosurgery

Three-dimensional printing in vascular neurosurgery is trending and is useful for the visualization of intracranial aneurysms for both neurosurgeons and trainees. The 3D models gives the surgeon time to practice beforehand and plan the surgery accordingly. The aim of the study of Ozgıray et al. was to examine the effect of preoperative planning with 3D printing models of aneurysms in terms of surgical time and patient outcomes.

Forty patients were prospectively enrolled in this study and divided into two groups: Groups I and II. In group I, only the angiograms were studied before surgery. Solid 3D modeling was performed only for group II before the operation and was studied accordingly. All surgeries were performed by the same senior vascular neurosurgeon. Demographic data, surgical data, both preoperative and postoperative modified Rankin Scale scores (mRS), and Glasgow Outcome Scores (GOS) were evaluated.

The average time of surgery was shorter in Group II, and the difference was statistically significant between the two groups (p < 0.001). However, no major differences were found for the GOS, hospitalization time, or mRS.

This study is the first prospective study of the utility of 3D aneurysm models. They show that 3D models are useful in surgery preparation. In the near future, these models will be used widely to educate trainees and pre-plan surgical options for senior surgeons 4).

Anesthesia

The guidelines relevant to the anesthesiologists in the day-to-day perioperative management of patients with ruptured intracranial aneurysm given by various societies are:

Diringer MN, Bleck TP, Claude Hemphill J, 3rd, Menon D, Shutter L, Vespa P, et al. Critical care management of patients following aneurysmal subarachnoid hemorrhage: Recommendations from the Neurocritical Care Society’s Multidisciplinary Consensus Conference. Neurocrit Care. 2011;15:211–40.

Bederson JB, Connolly ES, Jr, Batjer HH, Dacey RG, Dion JE, Diringer MN, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke. 2009;40:994–1025.

Steiner T, Juvela S, Unterberg A, Jung C, Forsting M, Rinkel G, et al. European Stroke Organization guidelines for the management of intracranial aneurysms and subarachnoid haemorrhage. Cerebrovasc Dis. 2013;35:93–112.

Both intravenous and inhalational anesthetic technique may be used for maintenance keeping in mind the objectives of stable intraoperative hemodynamics, early smooth recovery and effect on special monitoring techniques. Cerebral perfusion increases with isoflurane when compared with propofol without increase in ICP in aSAH.

Hypocapnia is not essential in good grade patients as it can reduce ICP and increase transmural pressure within aneurysmal sac predisposing it to rupture. In poor grade patients, hyperventilation however is beneficial to reduce ICP and provide lax brain.

Brain laxity is crucial to obtain good surgical access to the aneurysm without causing IOAR or compromising underlying brain from excessive retractor pressure. This is important as early surgery risks a tense/full brain and dissection without adequate exposure can result in IOAR. Both 20% mannitol and 3% hypertonic saline are suitable osmotic agents for intraoperative brain relaxation in the dose of 2-4 ml/kg. Head end elevation, avoiding jugular venous compression, avoiding high concentration of inhalational agents and nitrous-oxide and mild hyperventilation are other measures to achieve a lax brain. If full brain persists, additional measures like moderate hyperventilation, switching to intravenous anesthetic maintenance and release of cerebrospinal fluid might be helpful. 5).

Approaches

Pterional approach via standard frontotemporal craniotomy and interhemispheric approach via bifrontal craniotomy is the gold standard for clipping of cerebral aneurysms in the anterior circulation. Endovascular treatment is now widely used, but subsets of aneurysms are still indicated for surgical clipping. Modern technological advances allow less invasive clipping techniques such as the keyhole approach. Mori and Watanabe discussed the surgical indications, preoperative simulation, surgical techniques, and pros and cons of keyhole (supraorbital) clipping. Selection of standard craniotomy or keyhole craniotomy should be uncontroversial, but keyhole clipping requires definite surgical indications based on the characteristics of the target aneurysm for safe clipping 6).

To enhance visual confirmation of regional anatomy, endoscopy was introduced.

see Endoscopic endonasal approach for intracranial aneurysm

Outcome

see Intracranial aneurysm clipping outcome.

Complications

see Intracranial aneurysm clipping complications.

Postclipping evaluation

A challenge is to ensure noninclusion of normal vessel/perforators within the clip and perform complete aneurysmal isolation. This is done with either intraoperative microvascular Doppler sonography (IMD) or Indocyanine green videoangiography (ICG-VA) as they are simple and safe. Anesthesiologists administer ICG and also help perform IMD. ICG-VA appropriately assessed vessel patency and aneurysm obliteration in 93.5% of 109 aneurysms clipped 7) However, ICG can cause transient oxygen desaturation 8). IMD use confirms aneurysm isolation and patency of parent vessel and branching arteries. Hui et al. observed that clip repositioning was required based on IMD findings in 24% of aneurysms clipped in 91 patients and concluded that IMD could reduce the rate of residual aneurysm and unanticipated vessel stenosis 9).

The complete clipping of a cerebral aneurysm usually warrants its sustained occlusion, while clip remnants may have far-reaching consequences. The aim of this study is to identify the risk factors for clip remnants requiring retreatment and/or exhibiting growth. METHODS All consecutive patients with primary aneurysm clipping performed at University Hospital of Essen between January 1, 2003, and December 31, 2013, were eligible for this study. Aneurysm occlusion was judged on obligatory postoperative digital subtraction angiography and the need for repeated vascular control. The identified clip remnants were correlated with various demographic and clinical characteristics of the patients, aneurysm features, and surgery-related aspects. RESULTS Of 616 primarily clipped aneurysms, postoperative angiography revealed 112 aneurysms (18%) with clip remnants requiring further control (n = 91) or direct retreatment (n = 21). Seven remnants exhibited growth during follow-up, whereas 2 cases were associated with aneurysmal bleeding. Therefore, a total of 28 aneurysms (4.5%) were retreated as clip remnants (range 1 day to 67 months after clipping). In the multivariate analysis, the need for retreatment of clip remnant was correlated with the aneurysm’s initial size (> 12 mm; OR 3.22; p = 0.035) and location (anterior cerebral artery > internal carotid artery > posterior circulation > middle cerebral artery; OR 1.85; p = 0.003). Younger age with a cutoff at 45 years (OR 33.31; p = 0.004) was the only independent predictor for remnant growth. CONCLUSIONS The size and location of the aneurysm are the main risk factors for clip remnants requiring retreatment. Because of the risk for growth, younger individuals (< 45 years old) with clip remnants require a long-term (> 5 years) vascular follow-up. Clinical trial registration no: DRKS00008749 (Deutsches Register Klinischer Studien) 10).

Costs

Total index hospitalization costs for clipping are lower than for coiling. Costs of clipping and coiling are driven by different clinical variables. The cost of coils and devices is the predominant contributor to the higher total costs of coiling 11).

Virtual reality simulator for aneurysmal clipping surgery

see Virtual reality simulator for aneurysmal clipping surgery.

1)

Lai LT, O’Neill AH. History, Evolution and Continuing Innovations of Intracranial Aneurysm Surgery. World Neurosurg. 2017 Feb 9. pii: S1878-8750(17)30166-3. doi: 10.1016/j.wneu.2017.02.006. [Epub ahead of print] Review. PubMed PMID: 28189863.
2)

Sato A, Koyama JI, Hanaoka Y, Hongo K. A Reverse-Action Clip Applier for Aneurysm Surgery. Neurosurgery. 2015 Mar 12. [Epub ahead of print] PubMed PMID: 25774701.
3)

Santiago BM, Cunha E Sá M. How do we maintain competence in aneurysm surgery. Acta Neurochir (Wien). 2015 Jan;157(1):9-11. doi: 10.1007/s00701-014-2265-8. Epub 2014 Nov 14. PubMed PMID: 25391972.
4)

Ozgıray E, Husemoglu B, Cınar C, Bolat E, Akınturk N, Bıceroglu H, Kızmazoglu C. The Effect of Preoperative Three Dimensional Modeling and Simulation on Outcome of Intracranial Aneursym Surgery. J Korean Neurosurg Soc. 2023 Sep 15. doi: 10.3340/jkns.2023.0035. Epub ahead of print. PMID: 37709549.
5)

Sriganesh K, Venkataramaiah S. Concerns and challenges during anesthetic management of aneurysmal subarachnoid hemorrhage. Saudi J Anaesth. 2015 Jul-Sep;9(3):306-13. doi: 10.4103/1658-354X.154733. Review. PubMed PMID: 26240552; PubMed Central PMCID: PMC4478826.
6)

Mori K, Watanabe S. Keyhole Approach in Cerebral Aneurysm Surgeries. Adv Tech Stand Neurosurg. 2022;44:265-275. doi: 10.1007/978-3-030-87649-4_15. PMID: 35107685.
7)

Özgiray E, Aktüre E, Patel N, Baggott C, Bozkurt M, Niemann D, et al. How reliable and accurate is indocyanine green video angiography in the evaluation of aneurysm obliteration? Clin Neurol Neurosurg. 2013;115:870–8.
8)

Sriganesh K, Vinay B, Bhadrinarayan V. Indocyanine green dye administration can cause oxygen desaturation. J Clin Monit Comput. 2013;27:371.
9)

Hui PJ, Yan YH, Zhang SM, Wang Z, Yu ZQ, Zhou YX, et al. Intraoperative microvascular Doppler monitoring in intracranial aneurysm surgery. Chin Med J (Engl) 2013;126:2424–9.
10)

Jabbarli R, Pierscianek D, Wrede K, Dammann P, Schlamann M, Forsting M, Müller O, Sure U. Aneurysm remnant after clipping: the risks and consequences. J Neurosurg. 2016 Feb 12:1-7. [Epub ahead of print] PubMed PMID: 26871206.
11)

Duan Y, Blackham K, Nelson J, Selman W, Bambakidis N. Analysis of short-term total hospital costs and current primary cost drivers of coiling versus clipping for unruptured intracranial aneurysms. J Neurointerv Surg. 2014 Jun 2. pii: neurintsurg-2014-011249. doi: 10.1136/neurintsurg-2014-011249. [Epub ahead of print] PubMed PMID: 24891453.
  1. What is the primary purpose of intracranial aneurysm clipping? a) To reduce blood pressure b) To remove the aneurysm entirely c) To prevent the aneurysm from rupturing by sealing it off d) To increase blood flow to the aneurysm
  2. What is the first step in the intracranial aneurysm clipping procedure? a) Clipping the aneurysm b) Closing the incision c) Anesthesia d) Accessing the aneurysm
  3. Which type of anesthesia is typically used during intracranial aneurysm clipping? a) Local anesthesia b) Regional anesthesia c) General anesthesia d) Spinal anesthesia
  4. What is the purpose of a craniotomy in intracranial aneurysm clipping? a) To access the brain and the aneurysm b) To close the incision in the scalp c) To perform angiography d) To remove the aneurysm
  5. How is the aneurysm sealed off during clipping? a) By removing the aneurysm entirely b) By injecting a special sealing material c) By placing a tiny metal clip across its base d) By cauterizing it with heat
  6. After successfully clipping the aneurysm, what is the next step in the procedure? a) Performing additional imaging studies b) Closing the incision in the scalp c) Administering postoperative antibiotics d) Checking the patient’s blood pressure
  7. What is one potential risk associated with intracranial aneurysm clipping? a) Loss of vision b) Heart attack c) Joint pain d) Infection
  8. Which factor determines whether intracranial aneurysm clipping or endovascular coiling is the preferred treatment? a) The patient’s preference b) The surgeon’s preference c) The characteristics of the aneurysm and the patient’s overall health d) The availability of equipment
  9. How has technology impacted the surgical treatment of intracranial aneurysms? a) It has made clipping obsolete b) It has made clipping the only available treatment option c) It has led to the development of more advanced clip designs d) It has eliminated the need for preoperative evaluation
  10. What is the role of three-dimensional printing in vascular neurosurgery? a) To create models of the surgical team b) To visualize intracranial aneurysms for surgical planning c) To replace the need for anesthesia d) To monitor patient vital signs during surgery

Answers:

  1. c) To prevent the aneurysm from rupturing by sealing it off from normal blood circulation.
  2. c) Anesthesia
  3. c) General anesthesia
  4. a) To access the brain and the aneurysm
  5. c) By placing a tiny metal clip across its base
  6. b) Closing the incision in the scalp
  7. d) Infection
  8. c) The characteristics of the aneurysm and the patient’s overall health
  9. c) It has led to the development of more advanced clip designs
  10. b) To visualize intracranial aneurysms for surgical planning

Test your knowledge about awake surgery for glioma systematic reviews

What was the median age of patients analyzed in the systematic review of awake surgery for glioma resection during pregnancy?

a) 25 years

b) 30.5 years

c) 35 years

d) 40 years

In the same review, what percentage of patients underwent awake surgery in the third trimester of pregnancy?

a) 25%

b) 50%

c) 67%

d) 83%

Which medications were used to achieve conscious sedation in 67% of the cases during awake surgery?

a) Remifentanil and propofol

b) Morphine and ketamine

c) Diazepam and midazolam

d) Aspirin and ibuprofen

What is the main conclusion of the systematic review of awake surgery for glioma resection during pregnancy?

a) Awake surgery is not a suitable option during pregnancy.

b) Awake surgery is safe during pregnancy with no maternal-fetal complications.

c) The long-term effects of awake surgery during pregnancy are well-determined.

d) Awake surgery should only be performed in the first trimester of pregnancy.

What parameters were evaluated in the systematic review regarding repeated surgery in awake conditions for diffuse glioma patients?

a) Blood pressure, heart rate, and oxygen saturation

b) Return to work, neurocognitive disorders, and epileptic seizures

c) Tumor size, location, and histology

d) Surgical complications, anesthesia duration, and hospital stay

How many patients returned to active socio-professional life after repeated surgery in the systematic review on repeated awake surgeries?

a) 15%

b) 41%

c) 78%

d) 85%

According to the systematic review on stress, anxiety, and depression in AC patients, what percentage of studies concluded that awake craniotomy does not increase stress, anxiety, and/or depression?

a) 10%

b) 33.3%

c) 66.7%

d) 95.8%

What was the most common psychological outcome evaluated in the studies included in the review on stress, anxiety, and depression in AC patients?

a) Mood swings

b) Neurocognitive disorders

c) Anxiety

d) Memory loss

In the systematic review on speech and language errors during awake craniotomy with DES, what percentage of errors were reported at the subcortical level?

a) 10%

b) 20%

c) 40%

d) 60%

According to the meta-analysis mentioned in the last paragraph, what is the main benefit associated with awake craniotomy with Electrostimulation during glioma resection?

a) Faster recovery of motor skills

b) Reduced surgical complications

c) Lower risk of long-term neurological and language deficits

d) Shorter anesthesia duration

Answers:

b) 30.5 years
b) 50%
a) Remifentanil and propofol
b) Awake surgery is safe during pregnancy with no maternal-fetal complications.
b) Return to work, neurocognitive disorders, and epileptic seizures
b) 41%
d) 95.8%
c) Anxiety
c) 40%
c) Lower risk of long-term neurological and language deficits

See Literature

Chronic subdural hematoma treatment

Chronic subdural hematoma treatment

Corticosteroids are associated with reduced recurrence but also increased morbidity. Drains reduce the risk of recurrence, but the position of drain (subdural vs subgaleal) did not influence recurrence. Middle meningeal artery embolization is a promising treatment warranting further evaluation in randomized trials 1).

Surgical therapies involve the irrigation and removal of the blood products, sometimes with partial resection of these vascular membranes 2).

Investigational medical therapies have employed various strategies, which include reducing the rate of microhemorrhage from the membranes, changing the osmotic environment, or altering angiogenesis 3).

Endovascular therapies are aimed at de-vascularizing these membranes 4) 5) 6) 7).

Providing a high level of evidence to propose a standard of care for this frequent pathology is of utmost importance. However, two surveys in the UK and in France have shown a wide range of practice, without major rationale 8) 9).

A variety of clinical factors must be taken into account in the treatment of chronic subdural hematoma (cSDH), and the multifaceted treatment paradigms continue to evolve 10).

There is lack of uniformity about the treatment strategies, such as the role of burr hole, twist drill, craniotomy, etc., in CSDH amongst various surgeons. There is also disagreement about the use of drain, irrigation, and steroid 11) 12).

Surgery is usually the treatment of choice, but conservative treatment may be a good alternative in some situations.

Chronic subdural hematoma surgery

see Chronic subdural hematoma surgery.

Middle Meningeal Artery Embolization

see Middle meningeal artery embolization for chronic subdural hematoma.

Systematic reviews

Chronic subdural hematoma recurrence after evacuation occurs in approximately 10% of chronic subdural hematomas, and the various Chronic subdural hematoma surgery interventions are approximately equivalent. Corticosteroids are associated with reduced recurrence but also increased morbidity. Drains reduce the risk of recurrence, but the position of drain (subdural vs subgaleal) did not influence recurrence. Middle meningeal artery embolization is a promising treatment warranting further evaluation in randomized trials 13).

Soleman et al., provide a systematic review of studies analysing the conservative treatment options and the natural history of cSDH. Of 231 articles screened, 35 were included in this systematic review. Studies evaluating the natural history and conservative treatment modalities of cSDH remain sparse and are predominantly of low level of evidence. The natural history of cSDH remains unclear and is analysed only in case reports or very small case series. “Wait and watch” or “wait and scan” management is indicated in patients with no or minor symptoms (Markwalder score 0-1). However, it seems that there are no clear clinical or radiological signs indicating whether the cSDH will resolve spontaneously or not (type C recommendation). In symptomatic patients who are not worsening or in a comatose state, oral steroid treatment might be an alternative to surgery (type C recommendation). Tranexamic acid proved effective in a small patient series (type C recommendation), but its risk of increasing thromboembolic events in patients treated with antithrombotic or anticoagulant medication is unclear. Angiotensin converting-enzyme inhibitors were evaluated only as adjuvant therapy to surgery, and their effect on the rate of recurrence remains debatable. Mannitol showed promising results in small retrospective series and might be a valid treatment modality (type C recommendation). However, the long treatment duration is a major drawback. Patients presenting without paresis can be treated with a platelet activating factor receptor antagonist (type C recommendation), since they seem to promote resolution of the haematoma, especially in patients with subdural hygromas or low-density haematomas on computed tomography. Lastly, atorvastatin seems to be a safe option for the conservative treatment of asymptomatic or mildly symptomatic cSDH patients (type C recommendation). In conclusion, the knowledge of the conservative treatment modalities for cSDH is sparse and based on small case series and low grade evidence. However, some treatment modalities seem promising even in symptomatic patients with large haematomas. Randomised controlled trials are currently underway, and will hopefully provide us with good evidence for or against the conservative treatment of cSDH 14).

Surveys

The aim of a study was to survey aspects of current practice in the UK and Ireland. A 1-page postal questionnaire addressing the treatment of primary (i.e. not recurrent) CSDH was sent to consultant SBNS members in March 2006. There were 112 responses from 215 questionnaires (52%). The preferred surgical technique was burr hole drainage (92%). Most surgeons prefer not to place a drain, with 27% never using one and 58% using drain only in one-quarter of cases or less. Only 11% of surgeons always place a drain, and only 30% place one in 75% of cases or more. The closed subdural-to-external drainage was most commonly used (91%) with closed subgaleal-to-external and subdural-to-peritoneal conduit used less often (3 and 4%, respectively). Only 5% of responders claimed to know the exact recurrence rate. The average perceived recurrence rate among the surgeons that never use drains and those who always use drains, was the same (both 11%). Most operations are performed by registrars (77%). Postoperative imaging is requested routinely by 32% of respondents and 57% of surgeons prescribe bed rest. Ninety four per cent surgeons employ conservative management in less than one-quarter of cases. Forty-two per cent of surgeons never prescribe steroids, 55% prescribe them to those managed conservatively. This survey demonstrates that there are diverse practices in the management of CSDH. This may be because of sufficiently persuasive evidence either does not exist or is not always taken into account. The current literature provides Class II and III evidence and there is a need for randomized studies to address the role of external drainage, steroids and postoperative bed rest 15).

Cenic et al. developed and administered a questionnaire to Canadian Neurosurgeons with questions relating to the management of chronic and subacute subdural hematoma. Our sampling frame included all neurosurgery members of the Canadian Neurosurgical Society.

Of 158 questionnaires, 120 were returned (response rate = 76%). The respondents were neurosurgeons with primarily adult clinical practices (108/120). Surgeons preferred one and two burr-hole craniostomy to craniotomy or twist-drill craniostomy as the procedure of choice for initial treatment of subdural hematoma (35.5% vs 49.5% vs 4.7% vs 9.3%, respectively). Craniotomy and two burr-holes were preferred for recurrent subdural hematomas (43.3% and 35.1%, respectively). Surgeons preferred irrigation of the subdural cavity (79.6%), use of a subdural drain (80.6%), and no use of anti-convulsants or corticosteroids (82.1% and 86.6%, respectively). We identified a lack of consensus with keeping patients supine following surgery and post-operative antibiotic use.

The survey has identified variations in practice patterns among Canadian Neurosurgeons with respect to treatment of subacute or chronic subdural hematoma (SDH). Our findings support the need for further prospective studies and clinical trials to resolve areas of discrepancies in clinical management and hence, standardize treatment regimens 16).

Steroids

Steroids for chronic subdural hematoma.

Goreisan

see Goreisan for chronic subdural hematoma

Chronic subdural hematoma seizure prophylaxis

see Chronic subdural hematoma seizure prophylaxis.

Anticoagulation resumption after chronic subdural hematoma

Anticoagulation resumption after chronic subdural hematoma.

References

1) , 13)

Henry J, Amoo M, Kissner M, Deane T, Zilani G, Crockett MT, Javadpour M. Management of Chronic Subdural Hematoma: A Systematic Review and Component Network Meta-analysis of 455 Studies With 103 645 Cases. Neurosurgery. 2022 Dec 1;91(6):842-855. doi: 10.1227/neu.0000000000002144. Epub 2022 Sep 28. PMID: 36170165.
2)

Markwalder TM . The course of chronic subdural hematomas after burr-hole craniostomy with and without closed-system drainage. Neurosurg Clin N Am 2000;11:541–6.doi:10.1016/S1042-3680(18)30120-7
3)

Sun TF , Boet R , Poon WS . Non-surgical primary treatment of chronic subdural haematoma: preliminary results of using dexamethasone. Br J Neurosurg 2005;19:327–33.doi:10.1080/02688690500305332
4)

Link TW , Boddu S , Marcus J , et al . Middle meningeal artery embolization as treatment for chronic subdural hematoma: a case series. Oper Neurosurg 2018;14:556–62.doi:10.1093/ons/opx154
5)

Link TW , Boddu S , Paine SM , et al . Middle meningeal artery embolization for chronic subdural hematoma: a series of 60 cases. Neurosurgery 2018;121.doi:10.1093/neuros/nyy521
6)

Link TW , Rapoport BI , Paine SM , et al . Middle meningeal artery embolization for chronic subdural hematoma: Endovascular technique and radiographic findings. Interv Neuroradiol 2018;24:455–62.doi:10.1177/1591019918769336
7)

Link TW , Schwarz JT , Paine SM , et al . Middle meningeal artery embolization for Chronic subdural hematoma recurrence: a case series. World Neurosurg 2018;118:e570–4.doi:10.1016/j.wneu.2018.06.241
8)

M. Guénot, Hématome sous-dural chronique. Introduction et résultats de l’enquête de la SFNC, Neurochirurgie 4 (2001) 459–460 https://doi.org/ NCHIR-11-2001-47- 5-0028-3770-101019-ART7.
9)

] T. Santarius, R. Lawton, P.J. Kirkpatrick, P.J. Hutchinson, The management of primary chronic subdural haematoma: a questionnaire survey of practice in the United Kingdom and the Republic of Ireland, Br. J. Neurosurg. 22 (2008) 529–534, https://doi.org/10.1080/02688690802195381.
10)

Sahyouni R, Goshtasbi K, Mahmoodi A, Tran DK, Chen JW. Chronic Subdural Hematoma: A Historical and Clinical Perspective. World Neurosurg. 2017 Dec;108:948-953. doi: 10.1016/j.wneu.2017.09.064. Epub 2017 Sep 19. Review. PubMed PMID: 28935548.
11) , 15)

Santarius T, Lawton R, Kirkpatrick PJ, Hutchinson PJ. The management of primary chronic subdural haematoma: a questionnaire survey of practice in the United Kingdom and the Republic of Ireland. Br J Neurosurg. 2008 Aug;22(4):529-34. doi: 10.1080/02688690802195381. PubMed PMID: 18686063.
12)

Cenic A, Bhandari M, Reddy K. Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci. 2005 Nov;32(4):501-6. PubMed PMID: 16408582.
14)

Soleman J, Noccera F, Mariani L. The conservative and pharmacological management of chronic subdural haematoma. Swiss Med Wkly. 2017 Jan 19;147:w14398. doi: smw.2017.14398. PubMed PMID: 28102879.
16)

Cenic A, Bhandari M, Reddy K. Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci. 2005 Nov;32(4):501-6. PubMed PMID: 16408582.

t

A variety of clinical factors must be taken into account in the treatment of chronic subdural hematoma (cSDH), and the multifaceted treatment paradigms continue to evolve 1).

There is lack of uniformity about the treatment strategies, such as the role of burr hole, twist drill, craniotomy, etc., in CSDH amongst various surgeons. There is also disagreement about the use of drain, irrigation, and steroid 2) 3).

Surgery is usually the treatment of choice, but conservative treatment may be a good alternative in some situations.

see DECSA trial.

see Middle Meningeal Artery Embolization.

Chronic subdural hematoma surgery

see Chronic subdural hematoma surgery.

Systematic reviews

Soleman et al., provide a systematic review of studies analysing the conservative treatment options and the natural history of cSDH. Of 231 articles screened, 35 were included in this systematic review. Studies evaluating the natural history and conservative treatment modalities of cSDH remain sparse and are predominantly of low level of evidence. The natural history of cSDH remains unclear and is analysed only in case reports or very small case series. “Wait and watch” or “wait and scan” management is indicated in patients with no or minor symptoms (Markwalder score 0-1). However, it seems that there are no clear clinical or radiological signs indicating whether the cSDH will resolve spontaneously or not (type C recommendation). In symptomatic patients who are not worsening or in a comatose state, oral steroid treatment might be an alternative to surgery (type C recommendation). Tranexamic acid proved effective in a small patient series (type C recommendation), but its risk of increasing thromboembolic events in patients treated with antithrombotic or anticoagulant medication is unclear. Angiotensin converting-enzyme inhibitors were evaluated only as adjuvant therapy to surgery, and their effect on the rate of recurrence remains debatable. Mannitol showed promising results in small retrospective series and might be a valid treatment modality (type C recommendation). However, the long treatment duration is a major drawback. Patients presenting without paresis can be treated with a platelet activating factor receptor antagonist (type C recommendation), since they seem to promote resolution of the haematoma, especially in patients with subdural hygromas or low-density haematomas on computed tomography. Lastly, atorvastatin seems to be a safe option for the conservative treatment of asymptomatic or mildly symptomatic cSDH patients (type C recommendation). In conclusion, the knowledge of the conservative treatment modalities for cSDH is sparse and based on small case series and low grade evidence. However, some treatment modalities seem promising even in symptomatic patients with large haematomas. Randomised controlled trials are currently underway, and will hopefully provide us with good evidence for or against the conservative treatment of cSDH 4).

Surveys

The aim of a study was to survey aspects of current practice in the UK and Ireland. A 1-page postal questionnaire addressing the treatment of primary (i.e. not recurrent) CSDH was sent to consultant SBNS members in March 2006. There were 112 responses from 215 questionnaires (52%). The preferred surgical technique was burr hole drainage (92%). Most surgeons prefer not to place a drain, with 27% never using one and 58% using drain only in one-quarter of cases or less. Only 11% of surgeons always place a drain, and only 30% place one in 75% of cases or more. The closed subdural-to-external drainage was most commonly used (91%) with closed subgaleal-to-external and subdural-to-peritoneal conduit used less often (3 and 4%, respectively). Only 5% of responders claimed to know the exact recurrence rate. The average perceived recurrence rate among the surgeons that never use drains and those who always use drains, was the same (both 11%). Most operations are performed by registrars (77%). Postoperative imaging is requested routinely by 32% of respondents and 57% of surgeons prescribe bed rest. Ninety four per cent surgeons employ conservative management in less than one-quarter of cases. Forty-two per cent of surgeons never prescribe steroids, 55% prescribe them to those managed conservatively. This survey demonstrates that there are diverse practices in the management of CSDH. This may be because of sufficiently persuasive evidence either does not exist or is not always taken into account. The current literature provides Class II and III evidence and there is a need for randomized studies to address the role of external drainage, steroids and postoperative bed rest 5).

Cenic et al. developed and administered a questionnaire to Canadian Neurosurgeons with questions relating to the management of chronic and subacute subdural hematoma. Our sampling frame included all neurosurgery members of the Canadian Neurosurgical Society.

Of 158 questionnaires, 120 were returned (response rate = 76%). The respondents were neurosurgeons with primarily adult clinical practices (108/120). Surgeons preferred one and two burr-hole craniostomy to craniotomy or twist-drill craniostomy as the procedure of choice for initial treatment of subdural hematoma (35.5% vs 49.5% vs 4.7% vs 9.3%, respectively). Craniotomy and two burr-holes were preferred for recurrent subdural hematomas (43.3% and 35.1%, respectively). Surgeons preferred irrigation of the subdural cavity (79.6%), use of a subdural drain (80.6%), and no use of anti-convulsants or corticosteroids (82.1% and 86.6%, respectively). We identified a lack of consensus with keeping patients supine following surgery and post-operative antibiotic use.

The survey has identified variations in practice patterns among Canadian Neurosurgeons with respect to treatment of subacute or chronic subdural hematoma (SDH). Our findings support the need for further prospective studies and clinical trials to resolve areas of discrepancies in clinical management and hence, standardize treatment regimens 6).

Glucocorticoids

Since glucocorticoids have been used for treatment of cSDH in 1962 their role is still discussed controversially in lack of evident data. On the basis of the ascertained inflammation cycle in cSDH dexamethasone will be an ideal substance for a short lasting, concomitant treatment protocol.

A study is designed as a double-blind randomized placebo-controlled trial 820 patients who are operated for cSDH and from the age of 25 years are included after obtaining informed consent. They are randomized for administration of dexamethasone (16-16-12-12-8-4 mg/d) or placebo (maltodextrin) during the first 48 hours after surgery. The type I error is 5% and the type II error is 20%. The primary endpoint is the reoperation within 12 weeks postoperative.

This study tests whether dexamethasone administered over 6 days is a safe and potent agent in relapse prevention for evacuated cSDH 7).

Chronic subdural hematoma seizure prophylaxis

see Chronic subdural hematoma seizure prophylaxis.

Anticoagulation resumption after chronic subdural hematoma

Anticoagulation resumption after chronic subdural hematoma.

References

1)

Sahyouni R, Goshtasbi K, Mahmoodi A, Tran DK, Chen JW. Chronic Subdural Hematoma: A Historical and Clinical Perspective. World Neurosurg. 2017 Dec;108:948-953. doi: 10.1016/j.wneu.2017.09.064. Epub 2017 Sep 19. Review. PubMed PMID: 28935548.
2) , 5)

Santarius T, Lawton R, Kirkpatrick PJ, Hutchinson PJ. The management of primary chronic subdural haematoma: a questionnaire survey of practice in the United Kingdom and the Republic of Ireland. Br J Neurosurg. 2008 Aug;22(4):529-34. doi: 10.1080/02688690802195381. PubMed PMID: 18686063.
3)

Cenic A, Bhandari M, Reddy K. Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci. 2005 Nov;32(4):501-6. PubMed PMID: 16408582.
4)

Soleman J, Noccera F, Mariani L. The conservative and pharmacological management of chronic subdural haematoma. Swiss Med Wkly. 2017 Jan 19;147:w14398. doi: smw.2017.14398. PubMed PMID: 28102879.
6)

Cenic A, Bhandari M, Reddy K. Management of chronic subdural hematoma: a national survey and literature review. Can J Neurol Sci. 2005 Nov;32(4):501-6. PubMed PMID: 16408582.
7)

Emich S, Richling B, McCoy MR, Al-Schameri RA, Ling F, Sun L, Wang Y, Hitzl W. The efficacy of dexamethasone on reduction in the reoperation rate of chronic subdural hematoma – the DRESH study: straightforward study protocol for a randomized controlled trial. Trials. 2014 Jan 6;15(1):6. doi: 10.1186/1745-6215-15-6. PubMed PMID: 24393328; PubMed Central PMCID: PMC3891985.

Basal ganglia hemorrhage surgery

Basal ganglia hemorrhage surgery

Latest Pubmed Related Articles

Techniques

The main surgical techniques for spontaneous basal ganglia hemorrhage include stereotactic aspiration, endoscopic aspiration, and craniotomy. However, credible evidence is still needed to validate the effect of these techniques.

Craniotomy

Craniotomy for basal ganglia hemorrhage evacuation.

Decompressive craniectomy

Outcome analysis was stratified using hematoma volume, ICH score, preoperative GCS score, and decompressive craniectomy (DC).

Results: The mean hematoma volume was 70.8 mL, and 68 patients (26.9%) underwent DC. The mean postoperative ICP was 28.8 ± 6.7 mmHg for patients without DC, and only 17.5 ± 8.6 mmHg for patients with DC. Twenty-five patients (9.9%) died within 30 days of the operation, and 88 patients (34.8%, GOS ≥ 4) had good outcome 3 months after surgery. ICH volume > 50 mL, preoperative GCS score ≤ 8, and ICH score ≥ 3 are risk factors for unfavorable outcomes.

Conclusions: DC can be used for patients with low preoperative GCS score, and it effectively reduces ICP and 30-day mortality. Hematoma volume, preoperative GCS score, and ICH score are of predictive value for surgical outcome of large basal ganglia hemorrhage 1).

Stereotactic aspiration

Stereotactic aspiration for basal ganglia hemorrhage evacuation.

Endoscopic aspiration

Endoscopic aspiration for basal ganglia hemorrhage evacuation.

Laser navigation combined with XperCT technology-assisted puncture

A total of 61 patients with hypertensive basal ganglia hemorrhage were recruited at the Binzhou Medical University Hospital, between October 2019 and January 2021, and their clinical information was retrospectively analyzed. Based on the surgical approach used, patients were assigned into either laser navigation or small bone window groups depending on the surgical approach. Then, they compared the operation times, intraoperative blood loss, clinic stay, Glasgow Outcome Scale (GOS) rating at 30 days, Barthel index (BI) rating at 6 months, postoperative pneumonia incidences, and intracranial contamination complications between groups. Intraoperative blood loss, operation time, and sanatorium were significantly low in the laser navigation group, relative to the small bone window group. At the same time, there were no significant differences between the groups with regard to postoperative hematoma volume, lung contamination, cerebrospinal fluid (CSF) leak, and intracranial contamination, as well as the 6-month BI and 30-day GOS rating. There were no deaths in either group. Compared with traditional small bone window surgery, laser-guided puncture, and drainage is a low-cost, accurate, and safe method for the treatment of basal ganglia hemorrhage, which is suitable for promotion in developing countries and economically underdeveloped areas 2)

Complications

Postoperative hemorrhage is a severe complication, and it’s relative to neurosurgical techniques.

The favorable outcome group was slightly younger (p-value 0.050*). Also, the volume and extension of hematoma into the ventricular system, hydrocephalic dilatation, and midline shift greater than 5 mm had a significantly worse outcome with a statistically significant difference.

The early surgical management with the removal of the hematoma led to a dramatic reduction of ICP and improved the prognosis. Patients with signs of brain herniation, a midline shift > 5 mm, hydrocephalic dilatation, ventricular hemorrhage, and a depressed level of consciousness have a poor prognosis 3)

References

1)

Li Q, Yang CH, Xu JG, Li H, You C. Surgical treatment for large spontaneous basal ganglia hemorrhage: retrospective analysis of 253 cases. Br J Neurosurg. 2013 Oct;27(5):617-21. doi: 10.3109/02688697.2013.765938. Epub 2013 Feb 14. PMID: 23406426.
2)

Yuan Z, Wei Q, Chen Z, Xing H, Zhang T, Li Z. Laser navigation combined with XperCT technology-assisted puncture of basal ganglia intracerebral hemorrhage. Neurosurg Rev. 2023 May 5;46(1):104. doi: 10.1007/s10143-023-02015-2. PMID: 37145343.
3)

khallaf, M., Abdelrahman, M. Surgical management for large hypertensive basal ganglionic hemorrhage: single center experience. Egypt J Neurosurg 34, 19 (2019). https://doi.org/10.1186/s41984-019-0044-9

Burr hole trephination for chronic subdural hematoma

Burr hole trephination for chronic subdural hematoma

Burr hole trephination for drainage of chronic subdural hematomas are routine operative procedures done by neurosurgery residents.

Burr hole trephination for chronic subdural hematoma with a closed drainage system

Double burr hole trepanation combined with a subperiostal passive closed-drainage system is a technically easy, highly effective, safe, and cost-efficient treatment strategy for symptomatic chronic subdural hematomas. The absence of a drain in direct contact with the hematoma capsule may moderate the risk of postoperative seizure and limit the secondary spread of infection to intracranial compartments 1).

The main aim of surgery should be a complete removal of the aggressive liquid. In case of many membranes that separate the hematoma into chambers like honeycomb an open procedure cannot be avoided. Nevertheless, the preferred operative therapy for most of CSDH is a burr hole craniostomy with a closed drainage system 2) 3).

Surgical Technique

Surgical safety checklist

see Surgical safety checklist.

Preoperative antibiotic prophylaxis

see Preoperative antibiotic prophylaxis.

Skin Preparation

see Skin Preparation.

Positioning

Preferably under general anesthesia the surgical approach should be over the thickest part of the hematoma and the patients positioned in a way that the burr hole comes to the highest point to avoid pneumocephalus.

Therefore, the head is rotated and the ipsilateral shoulder is usually padded.

The supine position is used with the patient‘s head rotated for temporal access. Extremes of head rotation can obstruct the jugular venous drainage, and a shoulder roll can combat this problem or lateral positioning (park bench position).

Skin incision

Sites of predilection are frontal about 1 cm anterior to the coronal suture or parietal posterior to the parietal eminence. The area around Kocher’s point offers a safe entry without injury of branches of the middle meningeal artery or the motor strip. Additionally, the skin incision should be brought, if possible, into alignment with an eventual future skin flap for craniotomy. A curved flap avoids a burr hole position directly under the skin cut and a possible impaired wound-healing as a consequence. Further, the base of the C-shaped incision should be opposite of the planned direction of the drain tip. Obviously, a kinking of the drain is obviated 4).

Burr Holes

A performed burr hole with a diameter of 14 mm enables a sufficient angulation of the drain tip and allows an insertion of the drainage close to the calvaria.

Diren and Ozdemir found that an increase in the width of burr hole craniotomy (BHC), especially the posterior BHC, contributed to the improvement in midline shift 5).

Dura mater opening

The dura mater is coagulated and cut in a stellate fashion.

Technical issues

Under direct vision, the external membrane is perforated by the tips of the bipolar forceps. In general, there are the open or the closed ways of evacuation of the hematoma after the drain is inserted 6)

The open variant should be chosen only if irrigation is desired: the dura and external membrane are opened widely so that the fluid of the hematoma and irrigation can drip out beside the drain during rinsing. Removal of the fluid enriched with inflammatory mediators is considered obviously as an advantage, although a remaining pneumocephalus is seen as an approved factor of recurrence 7) 8).

In the closed way the aim is that no air enters the subdural space. Before the dural opening the drain is tunneled beneath the galea in the direction towards the middle of the base of the skin flap. A distance from the burr hole to the drain’s exit point of at least 5 cm prevents infection 9).

Then the dura and external membrane are incised. This opening should have the same diameter as the drain to allow for a watertight and airtight drain introduction. The hematoma can therefore be evacuated only through the drain: the more fluid that is going to be collected, the more negative pressure that will be built up, which helps the brain to unfold again.

The dura is covered with a small piece of a gelatin sponge and the burr hole is filled and with bone chips collected at the beginning.

The last steps are to connect the drain to a closed collecting system and secure the connection and the exit point from the skin with sutures.

Drain insertion after CSDH drainage is important, but position (subgaleal or subdural) and duration did not appear to influence recurrence rate or clinical outcomes. Similarly, drain location did not influence recurrence rate nor outcomes where both parietal and frontal burr holes were made. Further prospective cohort studies or randomized controlled trials could provide further clarification 10).

Videos

References

1)

Zumofen D, Regli L, Levivier M, Krayenbühl N. Chronic subdural hematomas treated by burr hole trepanation and a subperiostal drainage system. Neurosurgery. 2009 Jun;64(6):1116-21; discussion 1121-2. doi: 10.1227/01.NEU.0000345633.45961.BB. PubMed PMID: 19487891.
2)

Santarius T, Kirkpatrick PJ, Ganesan D, Chia HL, Jalloh I, Smielewski P, Richards HK, Marcus H, Parker RA, Price SJ, Kirollos RW, Pickard JD, Hutchinson PJ (2009) Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet 374:1067–1073
3)

Weigel R, Schmiedek P, Krauss JK (2003) Outcome of contemporary surgery for chronic subdural haematoma: evidence based review. J Neurol Neurosurg Psychiatry 74:937–943
4)

Emich S, Dollenz M, Winkler PA. Burr hole is not burr hole: technical considerations to the evacuation of chronic subdural hematomas. Acta Neurochir (Wien). 2015 Jan 13. [Epub ahead of print] PubMed PMID: 25578345.
5)

Diren F, Ozdemir O. The effectiveness of Burr-hole sizes on midline shift and hematoma thickness in the treatment of chronic subdural hematoma. World Neurosurg. 2023 Apr 20:S1878-8750(23)00546-6. doi: 10.1016/j.wneu.2023.04.062. Epub ahead of print. PMID: 37087033.
6)

Tosaka M, Sakamoto K, Watanabe S, Yodonawa M, Kunimine H, Aishima K, Fujii T, Yoshimoto Y (2013) Critical classification of craniostomy for chronic subdural hematoma; safer technique for hematoma aspiration. Neurol Med Chir (Tokyo) 53:273–278
7)

Mori K, Maeda M (2001) Surgical treatment of chronic subdural hematoma in 500 consecutive cases: clinical characteristics, surgical outcome, complications, and recurrence rate. Neurol Med Chir (Tokyo) 41:371–381
8)

Stanišić M, Hald J, Rasmussen IA, Pripp AH, Ivanović J, Kolstad F, Sundseth J, Züchner M, Lindegaard KF (2013) Volume and densities of chronic subdural haematoma obtained from CT imaging as predictors of postoperative recurrence: a prospective study of 107 operated patients. Acta Neurochir 155:323–333
9)

Berghauser Pont LM, Dammers R, Schouten JW, Lingsma HF, Dirven CM (2012) Clinical factors associated with outcome in chronic subdural haematoma: a retrospective cohort study of patients on preoperative corticosteroid therapy. Neurosurgery 70:873–880
10)

Glancz LJ, Poon MTC, Coulter IC, Hutchinson PJ, Kolias AG, Brennan PM. Does Drain Position and Duration Influence Outcomes in Patients Undergoing Burr-Hole Evacuation of Chronic Subdural Hematoma? Lessons from a UK Multicenter Prospective Cohort Study. Neurosurgery. 2019 Oct 1;85(4):486-493. doi: 10.1093/neuros/nyy366. PubMed PMID: 30169738.

Superficial temporal artery to middle cerebral artery bypass for moyamoya disease

Superficial temporal artery to middle cerebral artery bypass for moyamoya disease

The superficial temporal artery is a useful donor artery for direct bypass surgery for moyamoya disease and can provide sufficient blood supply to the ischemic cerebral territory 1).

Combined with a temporal muscle patch can deliver a higher total clinical curative rate for patients with moyamoya disease and can alleviate their coma 2).

Clinical success

Collateral artery formation from the extracranial carotid artery to ischemic brain tissue determines the clinical success of superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery in adult patients with moyamoya disease, but postoperative collateral formation (PCF) after STA-MCA bypass surgery is unpredictable. Accurate preoperative prediction of acceptable PCF could improve patient selection. Sun et al. aim to develop a prediction nomogram model for PCF in this patient population.

Adult patients with moyamoya disease undergoing the STA-MCA bypass surgery between January 2013 and December 2020 at a single institution were retrospectively or prospectively enrolled in this observational study. Data including potential clinical and radiological predictors were obtained from hospital records. A nomogram was generated based on a multivariate logistic regression analysis, to identify potential predictors associated with good PCF. The performance of the nomogram was evaluated for discrimination, calibration, and clinical utility.

Data from 243 patients with moyamoya disease who underwent the STA-MCA bypass surgery were analyzed to build the nomogram. After 1-year follow-up, 162 (66.7%) hemispheres had good PCF and 81 (33.3%) had poor PCF. Good PCF is associated with 3 preoperative factors: age at operation, the diameter of the donor branch of STA, and the preinfarction period stage. Incorporating these 3 factors, the model achieved a concordance index of 0.88 (95% CI, 0.84-0.92) and had a well-fitted calibration curve and good clinical application value. A cutoff value of 100 was determined to predict good PCF via this nomogram.

The nomogram exhibits high accuracy in predicting good PCF after the STA-MCA bypass surgery in adult patients with moyamoya disease and may allow surgeons to better evaluate preoperatively candidacy for successful bypass surgery 3).

Complications

Superficial temporal artery to middle cerebral artery bypass for moyamoya disease complications.

Case series

Data for consecutive patients who underwent STA-MCA MVB from 2000-2019 due to moyamoya/moyamoya-like disease, complex intracranial aneurysms, or intractable brain ischemia due to internal carotid artery or middle cerebral artery occlusive disease with repeated ischemic events were retrospectively analyzed under a waiver of informed consent. Key surgical steps and the important role of neuroendovascular interventions are presented. Surgical results and late outcomes were analyzed.

The study was comprised of 32 patients (17 women [53%], 15 men [47%]), mean age 42.94 years (range 16-66). Patients underwent 37 STA-MCA MVB procedures during the study period; 22 with moyamoya/moyamoya-like disease (69%) underwent 27 surgeries (five bilateral); 7 with complex aneurysms (22%) and 3 with vascular occlusive disease (9%) underwent unilateral bypass. Five of seven aneurysms were treated with coiling or flow-diverter stent implant prior to bypass surgery; two were clipped during the bypass procedure. There were no surgical complications, no perioperative mortality, and no death from complications related to neurovascular disease at late follow-up. Transient neurological deficits following 8/37 (21%) resolved with no permanent neurologic sequelae. Transient ischemic attacks occurred only in the immediate postoperative period in four patients (11%).

In specific cases, STA-MCA MVB is a feasible and clinically effective procedure. It is important to preserve this technique in surgical armamentarium 4).

From October 2005 to November 2009, Xu et al. from the Department of Neurosurgery, Fudan University, Shanghai, China performed a combined revascularization procedure in 111 patients with different types and stages of moyamoya disease. The superficial temporal artery, middle meningeal artery and the deep temporal artery were evaluated for individualized surgical planning in these cases. The integrity of the deep temporal artery and the middle meningeal artery network, and the pre-existing spontaneous anastomoses of the distal branches of the external carotid artery with the cortical arteries were well preserved. The mean follow-up time was 72.5 months, all clinical and radiological data were retrospectively reviewed.

A total of 198 stomas were performed in 122 hemispheres, all remaining patent until the last follow-up. The encephalo-duro-myo-synangiosis resulted in extensive anastomoses of the deep temporal artery (100%), the middle meningeal artery (90.9%), and the sphenopalatine artery (39.8%) with the cortical arteries, respectively. The superficial temporal artery, deep temporal artery, and the middle meningeal artery were significantly thickened in 88 patients as determined by digital subtraction angiography at follow-up. The relative cerebral blood flow increased significantly within one week after the operation. At 6 months post the operation, the relative cerebral blood flow was further increased by 15.5% from the gradual formation of anastomoses as a result of indirect revascularization. Transient ischemic attacks were effectively reduced or totally arrested. The neurological deficits significantly improved in 37 patients, with the National Institutes of Health Stroke Scale scores lowered by 2-8. There was no rehemorrhage in hemorrhagic moyamoya disease patients.

This study showed that the superficial temporal artery-middle cerebral artery bypass combined with encephalo-duro-myo-synangiosis can achieve good therapeutic effect in the moyamoya disease treatment 5).

1)

Wen Y, Gou Y, Wang B, Wang Z, Chen S, Zhang S, Zhang G, Li M, Feng W, Qi S, Wang G. Is STA really a low-flow graft? A quantitative ultrasonographic study of the flow of STA for cerebral revascularization in MMD patients. CNS Neurosci Ther. 2023 Apr 1. doi: 10.1111/cns.14197. Epub ahead of print. PMID: 37002791.
2)

Gao F, Chen S, Gu J, Wang Z, Wang Z. Clinical Efficacy of Superficial Temporal Artery-middle Cerebral Artery Bypass Grafting Surgery Combined With Temporal Muscle Patch on Patients With Moyamoya Disease. J Craniofac Surg. 2022 Sep 6. doi: 10.1097/SCS.0000000000008992. Epub ahead of print. PMID: 36731073.
3)

Sun H, Li Y, Xiao A, Li W, Xia C, You C, Ma L, Liu Y, Xia C. Nomogram to Predict Good Collateral Formation After the STA-MCA Bypass Surgery in Adult Patients With Moyamoya Disease. Stroke. 2023 Feb 7. doi: 10.1161/STROKEAHA.122.039975. Epub ahead of print. PMID: 36748463.
4)

Kahanov L, Cohen JE, Fraifeld S, Mizrahi C, Leker RR, Moscovici S, Spektor S. Superficial Temporal Artery-Middle Cerebral Artery Microvascular Bypass: Its Role in Treatment of Patients with Moyamoya Disease, Cerebral Aneurysms, and Vascular Occlusive Disease. Isr Med Assoc J. 2021 May;23(5):306-311. PMID: 34024048.
5)

Xu B, Song DL, Mao Y, Gu YX, Xu H, Liao YJ, Liu CH, Zhou LF. Superficial temporal artery-middle cerebral artery bypass combined with encephalo-duro-myo-synangiosis in treating moyamoya disease: surgical techniques, indications and midterm follow-up results. Chin Med J (Engl). 2012 Dec;125(24):4398-405. PMID: 23253709.

Trigeminal neuralgia

Trigeminal neuralgia

Latest Pubmed Related Articles

The facial pain syndrome known as trigeminal neuralgia was described more than 300 years ago 1).

Definition

Trigeminal neuralgia definition.

Epidemiology

see Trigeminal neuralgia epidemiology.

Classification

see Trigeminal neuralgia classification.

Pathogenesis

see Trigeminal neuralgia pathogenesis.

Pathophysiology

see Trigeminal neuralgia pathophysiology.

Natural History

Typical trigeminal neuralgia caused by microvascular compression of the trigeminal nerve root in the posterior fossa may become transformed over time into atypical trigeminal neuralgia, if left untreated. This transformation involves change in the character of pain and development of sensory impairment. Two representative cases are presented to support this theory.

If the theory of progressive change in character of pain and degree of sensory impairment in the course of otherwise typical trigeminal neuralgia is correct, trigeminal neuralgia, atypical neuralgia, and trigeminal neuropathic pain may represent different degrees of injury to the trigeminal nerve, therefore comprising a continuous spectrum rather than discrete diagnoses 2).

Clinical Features

Trigeminal neuralgia clinical features.

Scales

Barrow Neurological Institute Pain Scale.

Barrow Neurological Facial Numbness Scale.

Slavin KV. Commentary: Development and Evaluation of a Preoperative Trigeminal Neuralgia Scoring System to Predict Long-Term Outcome Following Microvascular Decompression. Neurosurgery. 2019 Dec 9. pii: nyz540. doi: 10.1093/neuros/nyz540. [Epub ahead of print] PubMed PMID: 31813971.

Diagnosis

Trigeminal neuralgia diagnosis.

Treatment

see Trigeminal neuralgia treatment.

Outcome

see Trigeminal neuralgia outcome.

Case series

see Trigeminal neuralgia case series.

Case reports

see Trigeminal neuralgia case reports.

1)

Lewy FH: The first authentic case of major trigeminal neuralgia and some comments on the history of this disease. Ann Med Hist 10:247–250, 1938.
2)

Burchiel KJ, Slavin KV. On the natural history of trigeminal neuralgia. Neurosurgery. 2000 Jan;46(1):152-4; discussion 154-5. Review. PubMed PMID: 10626945.

Flow Diverter Stent for Middle Cerebral Artery Aneurysm

Flow Diverter Stent for Middle Cerebral Artery Aneurysm

Middle cerebral artery aneurysms tend to be complex, with integrated branches and potentially wide necks. Pipeline embolization device stents are safe and effective in the middle cerebral artery aneurysm, and the patency of the side and jailed branches is preserved in most cases. Higher occlusion and lower in-stent stenosis rates are seen with longer follow-up durations 1).

However, compared to published series on the open surgical treatment of this subset of aneurysms, flow diversion has inferior outcomes and is associated with a higher rate of complications 2).

Flow diverter for middle cerebral artery aneurysm treatment should be considered an alternative when traditional treatment methods are not feasible 3).

When performed in a select treatment group, high rates of aneurysm occlusion and protection against re-rupture can be achieved 4).

Longer angiographic follow-ups are needed to assess the morphologic outcome; immediate subtotal occlusions do not seem to be related to rupture 5).

Findings suggest that complete occlusion after endovascular treatment with FDD can be delayed (>6 months). Ischemic complications may occur as early or delayed, particularly at clopidogrel interruption 6).

The Pipeline Embolization Device provides a safe and effective treatment alternative for wide-neck MCA aneurysms that give rise to a bifurcating or distal branch when other endovascular techniques are thought to be unfeasible or more risky 7).

WEB flow disruption seems to be a promising technique for the treatment of complex MCA aneurysms, particularly those with a wide neck or unfavorable dome-to-neck ratio 8).

For Caroff et al. compared with other available therapeutic options, the flow-diverter stent does not appear to be a suitable solution for the treatment of saccular MCA bifurcation aneurysms 9).

Unsatisfactory occlusion rate in bifurcation aneurysms likely results from residual filling of the aneurysms in cases in which the jailed side branch remains patent 10).

Systematic review and meta-analysis

A systematic search of PubMed, MEDLINE, and Embase was performed for studies published from 2008 to May 2017.

According to the Preferred Reporting Items for Systematic Reviews and MetaAnalyses, Cagnazzo et al. selected studies with >5 patients describing angiographic and clinical outcomes after flow-diversion treatment of MCA aneurysms.

Random effects metaanalysis was used to pool the following outcomes: aneurysm occlusion rate, procedure-related complications, rupture rate of treated aneurysms, and occlusion of the jailed branches.

Twelve studies evaluating 244 MCA aneurysms were included in this meta-analysis. Complete/near-complete occlusion was obtained in 78.7% (95% CI, 67.8%-89.7%) of aneurysms. The rupture rate of treated aneurysms during follow-up was 0.4% per aneurysm year. The rate of treatment-related complications was 20.7% (95% CI, 14%-27.5%), and approximately 10% of complications were permanent. The mortality rate was close to 2%. Nearly 10% (95% CI, 4.7%-15.5%) of jailed arteries were occluded during follow-up, whereas 26% (95% CI, 14.4%-37.6%) had slow flow. Rates of symptoms related to occlusion and slow flow were close to 5%.

Small and retrospective series could affect the strength of the reported results.

Given the not negligible rate of treatment-related complications, flow diversion for MCA aneurysms should be considered an alternative treatment when traditional treatment methods are not feasible. However, when performed in this select treatment group, high rates of aneurysm occlusion and protection against re-rupture can be achieved 11).

Case series

Flow Diverter Stent for Middle Cerebral Artery Aneurysm case series

Case reports

Burrows et al. present the case of an adolescent with a middle cerebral artery (MCA) fusiform aneurysm which recurred following clip reconstruction and bypass. The aneurysm was successfully treated with endovascular flow diversion 12).

1)

Soydemir E, Gündoğmuş CA, Türeli D, Andaç Baltacıoğlu N, Bayri Y, Baltacıoğlu F. Safety and efficacy of flow diverter stents in the treatment of middle cerebral artery aneurysms: a single-center experience and follow-up data. Diagn Interv Radiol. 2023 Mar 29;29(2):350-358. doi: 10.4274/dir.2022.211050. Epub 2023 Feb 1. PMID: 36988000.
2)

Diestro JDB, Adeeb N, Dibas M, Boisseau W, Harker P, Brinjikji W, Xiang S, Joyce E, Shapiro M, Raz E, Parra-Farinas C, Pickett G, Alotaibi NM, Regenhardt RW, Bernstock JD, Spears J, Griessenauer CJ, Burkhardt JK, Hafeez MU, Kan P, Grandhi R, Taussky P, Nossek E, Hong T, Zhang H, Rinaldo L, Lanzino G, Stapleton CJ, Rabinov JD, Patel AB, Marotta TR, Roy D, Dmytriw AA. Flow Diversion for Middle Cerebral Artery Aneurysms: An International Cohort Study. Neurosurgery. 2021 Nov 18;89(6):1112-1121. doi: 10.1093/neuros/nyab365. PMID: 34624100.
3)

Bhogal P, AlMatter M, Bäzner H, Ganslandt O, Henkes H, Aguilar Pérez M. Flow Diversion for the Treatment of MCA Bifurcation Aneurysms-A Single Centre Experience. Front Neurol. 2017 Feb 2;8:20. doi: 10.3389/fneur.2017.00020. eCollection 2017. PubMed PMID: 28210239; PubMed Central PMCID: PMC5288345.
4) , 11)

Cagnazzo F, Mantilla D, Lefevre PH, Dargazanli C, Gascou G, Costalat V. Treatment of Middle Cerebral Artery Aneurysms with Flow-Diverter Stents: A Systematic Review and Meta-Analysis. AJNR Am J Neuroradiol. 2017 Oct 5. doi: 10.3174/ajnr.A5388. [Epub ahead of print] PubMed PMID: 28982785.
5)

Iosif C, Mounayer C, Yavuz K, Saleme S, Geyik S, Cekirge HS, Saatci I. Middle Cerebral Artery Bifurcation Aneurysms Treated by Extrasaccular Flow Diverters: Midterm Angiographic Evolution and Clinical Outcome. AJNR Am J Neuroradiol. 2017 Feb;38(2):310-316. doi: 10.3174/ajnr.A5022. Epub 2016 Dec 15. PubMed PMID: 27979794.
6)

Briganti F, Delehaye L, Leone G, Sicignano C, Buono G, Marseglia M, Caranci F, Tortora F, Maiuri F. Flow diverter device for the treatment of small middle cerebral artery aneurysms. J Neurointerv Surg. 2016 Mar;8(3):287-94. doi: 10.1136/neurintsurg-2014-011460. Epub 2015 Jan 20. PubMed PMID: 25603808.
7)

Yavuz K, Geyik S, Saatci I, Cekirge HS. Endovascular treatment of middle cerebral artery aneurysms with flow modification with the use of the pipeline embolization device. AJNR Am J Neuroradiol. 2014 Mar;35(3):529-35. doi: 10.3174/ajnr.A3692. Epub 2013 Sep 26. PubMed PMID: 24072620.
8)

Pierot L, Klisch J, Cognard C, Szikora I, Mine B, Kadziolka K, Sychra V, Gubucz I, Januel AC, Lubicz B. Endovascular WEB flow disruption in middle cerebral artery aneurysms: preliminary feasibility, clinical, and anatomical results in a multicenter study. Neurosurgery. 2013 Jul;73(1):27-34; discussion 34-5. doi: 10.1227/01.neu.0000429860.04276.c1. PubMed PMID: 23615104.
9)

Caroff J, Neki H, Mihalea C, D’Argento F, Abdel Khalek H, Ikka L, Moret J, Spelle L. Flow-Diverter Stents for the Treatment of Saccular Middle Cerebral Artery Bifurcation Aneurysms. AJNR Am J Neuroradiol. 2016 Feb;37(2):279-84. doi: 10.3174/ajnr.A4540. Epub 2015 Sep 24. PubMed PMID: 26405085.
10)

Topcuoglu OM, Akgul E, Daglioglu E, Topcuoglu ED, Peker A, Akmangit I, Belen D, Arat A. Flow Diversion in Middle Cerebral Artery Aneurysms: Is It Really an All-Purpose Treatment? World Neurosurg. 2016 Mar;87:317-27. doi: 10.1016/j.wneu.2015.11.073. Epub 2015 Dec 23. PubMed PMID: 26723288.
12)

Burrows AM, Zipfel G, Lanzino G. Treatment of a pediatric recurrent fusiform middle cerebral artery (MCA) aneurysm with a flow diverter. J Neurointerv Surg. 2013 Nov;5(6):e47. doi: 10.1136/neurintsurg-2012-010478.rep. Epub 2012 Nov 27. PubMed PMID: 23188788.

Microvascular Decompression Complications

Microvascular Decompression Complications

Latest Pubmed Related Articles

Microvascular decompression (MVD) has a satisfactory safety, and it is the only surgical treatment for neurovascular compression diseases, such as hemifacial spasm, trigeminal neuralgia, and glossopharyngeal neuralgia, from the perspective of etiology.

Microvascular decompression (MVD) is a surgical procedure used to relieve pressure on a nerve root in the brainstem. While the procedure has a high success rate, like all surgeries, it does carry some risks and potential complications.

Some possible complications of microvascular decompression include:

Bleeding: Bleeding can occur during or after the surgery, which may require additional medical intervention.

Infection: Infection can occur at the site of the surgery or in the brain, which can lead to serious complications.

Nerve damage: Nerve damage can occur during the surgery, which may lead to a range of symptoms, including weakness, numbness, and paralysis.

Hearing loss: MVD can lead to hearing loss in some cases, particularly if the acoustic nerve is damaged during the procedure.

Balance problems: MVD can cause balance problems or vertigo, which may persist for several weeks or months after the surgery.

Cerebrospinal fluid leak: In rare cases, MVD can cause a cerebrospinal fluid leak, which may require further medical intervention.

It’s important to note that while these complications are possible, they are relatively rare.

Bilateral dilated and fixed pupils have long been regarded as a sign of life threatening, which is common in patients with brain herniation due to intracranial hypertension. However, transient dilated pupils after MVD have not been previously reported.

Wang et al. presented 2 patients with bilateral transient dilated and fixed pupils after MVD and discussed the possible etiologies through the literature review. Physical examination of both patients showed bilateral pupils were normal and without a medical history of pupil dilation. They underwent MVD under general anesthesia and used propofol and sevoflurane. In both cases, the vertebral artery was displaced, and Teflon pads were inserted between the vertebral artery and the brain stem. Postoperation, we found transient bilateral mydriasis without light reflection in both patients. The emergency head computed tomography revealed no obvious signs of hemorrhage and cerebral herniation. About 1 hour later, this phenomenon disappeared. Therefore, the authors think if MVD is successfully carried out, bilateral transient mydriasis may not necessarily indicate brain stem hemorrhage, cerebral herniation, and other emergency conditions, which can be recovered within a short time. The causes could be related to stimulation of the sympathetic pathway in the brain stem during MVD and side effects of anesthetics 1).

Microvascular decompression for trigeminal neuralgia complications

see Microvascular decompression for trigeminal neuralgia complications.

1)

Wang L, Fan H, Xu X, Su S, Feng W, Wu C, Chen Y. Bilateral Transient Dilated and Fixed Pupils After Microvascular Decompression: Rare Clinical Experience. J Craniofac Surg. 2023 Mar 21. doi: 10.1097/SCS.0000000000009293. Epub ahead of print. PMID: 36941233.

Olfactory groove meningioma

Olfactory groove meningioma

Olfactory groove meningiomas (OGMs) are arachnoid cell neoplasms of the frontoethmoidal suture and lamina cribrosa, 1) and may involve any part of the area from the crista galli to the planum sphenoidale 2) 3) 4).

Epidemiology

Olfactory groove meningioma epidemiology

Classification

Olfactory groove meningioma classification

Clinical features

Olfactory groove meningioma clinical features

Diagnosis

Olfactory groove meningioma diagnosis.

Differential diagnosis

Tuberculum sellae meningioma

Planum sphenoidale meningioma

Treatment

Olfactory groove meningioma treatment.

Complications

Olfactory groove meningioma complications

Books

The Meningiomas Arising from the Olfactory Groove and Their Removal by the Aid of Electro-surgery By Harvey Cushing · 1927

Cushing H, Eisenhardt L (1938) The olfactory meningiomas with primary anosmia. In: Cushing H, Eisenhardt L (eds) Meningiomas: their classification, regional behavior, life history, and surgical results. Charles C Thomas, Springfield, pp 250–282

Ojemann RG (1991) Olfactory groove meningiomas. In: Al-Mefty O (ed) Meningiomas. Raven Press, New York, pp 383–393

Al-Mefty O (1993) Tuberculum sellae and olfactory groove meningioma. In: Sekhar LN, Janecka IP (eds) Surgery of cranial base tumors. Raven Press, New York, pp 507–519

Surgery of Skull Base Meningiomas: With a Chapter Madjid Samii, ‎Mario Ammirati · 2012

Meningiomas of the Skull Base Treatment Nuances in Contemporary Neurosurgery 2018

Videos

Olfactory groove meningioma videos.

Systematic Reviews

A systematic review was performed to identify studies that compared outcomes following EEA and TCA for OGMs. Data extracted from each study included gross total resection (GTR), the incidence of cerebrospinal fluid (CSF) leaks, and post-operative complications including anosmia. The results of the search yielded 5 studies that met the criteria for inclusion and analysis. All studies compared TCA (n = 922) with EEA (n = 141) outcomes for OGMs. Overall, the rate of gross total resection (GTR) was lower among the endoscopic group (70.9%) relative to the transcranial group (91.5%). The rate of postoperative CSF leak was 6.3% vs. 25.5% for the transcranial and endoscopic groups, respectively. Post-operative anosmia was higher for patients undergoing EEA (95.9%) compared with patients in the transcranial group (37.4%). In this analysis, EEA was associated with a lower rate of GTR and higher incidences of CSF leaks and post-operative anosmia. However, with increasing surgeon familiarity with the endoscopic anatomy and technique for managing ASB pathologies, a nuanced approach may be used to minimize patient morbidity and widen the spectrum of skull base surgery 5).

Electronic databases were searched from inception until December 2019 for studies delineating TCAs for OGM patients. Patient demographics, pre-operative symptoms, surgical outcomes, and complications were evaluated and analyzed with a meta-analysis of proportions. Results: A total of 27 observational case series comparing 554 unilateral vs. 451 bilateral TCA patients were eligible for review. The weighted pooled incidence of gross total resection is 94.6% (95% CI, 90.7-97.5%; I 2 = 59.0%; p = 0.001) for unilateral and 90.9% (95% CI, 85.6-95.4%; I 2 = 58.1%; p = 0.003) for bilateral cohorts. Similarly, the incidence of OGM recurrence is 2.6% (95% CI, 0.4-6.0%; I 2 = 53.1%; p = 0.012) and 4.7% (95% CI, 1.4-9.2%; I 2 = 55.3%; p = 0.006), respectively. Differences in oncologic outcomes were not found to be statistically significant (p = 0.21 and 0.35, respectively). Statistically significant differences in complication rates in bilateral vs. unilateral TCA cohorts include meningitis (1.0 vs. 0.0%; p = 0.022) and mortality (3.2 vs. 0.2%; p = 0.007). Conclusions: While both cohorts have similar oncologic outcomes, bilateral TCA patients exhibit higher postoperative complication rates. This may be explained by underlying tumor characteristics necessitating more radical resection but may also indicate increased morbidity with bilateral approaches. However, evidence from more controlled, comparative studies is warranted to further support these findings 6).

A PubMed search of the recent literature (2011-2016) was performed to examine outcomes following EEA and TCA for OGM. The extent of resection, visual outcome, postoperative complications, and recurrence rates were analyzed using percentages and proportions, the Fischer exact test, and the Student’s t-test using GraphPad PRISM 7.0Aa (San Diego, CA) software.

Results: There were 444 patients in the TCA group with a mean diameter of 4.61 (±1.17) cm and 101 patients in the EEA group with a mean diameter of 3.55 (± 0.58) cm (p = 0.0589). GTR was achieved in 90.9% (404/444) in the TCA group and 70.2% (71/101) in the EEA group (p < 0.0001). Of the patients with preoperative visual disturbances, 80.7% (21/26) of patients in the EEA cohort had an improvement in vision compared to 12.83%(29/226) in the TCA group (p < 0.0001). Olfaction was lost in 61% of TCA and in 100% of EEA patients. CSF leaks and meningitis occurred in 25.7% and 4.95% of EEA patients and 6.3% and 1.12% of TCA patients, respectively (p < 0.0001; p = 0.023).

The updated literature review demonstrates that despite more experience with endoscopic resection and skull base reconstruction, the literature still supports TCA over EEA with respect to the extent of resection and complications. EEA may be an option in selected cases where visual improvement is the main goal of surgery and postoperative anosmia is acceptable to the patient or in medium-sized tumors with existing preoperative anosmia. Nevertheless, based on our results, it seems more prudent at this time to use TCA for the majority of OGMs 7).

Case series

Olfactory groove meningioma case series

Case reports

Olfactory groove meningioma case reports.

1)

Guinto G. Olfactory Groove Meningiomaas. World Neurosurg. 2015 Jun;83(6):1046-7. doi: 10.1016/j.wneu.2014.12.044. Epub 2015 Jan 14. PMID: 25596435.
2)

Hentschel SJ, DeMonte F, Olfactory groove meningiomas. DeMonte F, McDermott MW, Al-Mefty O: Al-Mefty’s Meningiomas 2New York, Thieme, 2011. 196–205
3)

Nakamura M, Struck M, Roser F, Vorkapic P, Samii M: Olfactory groove meningiomas: clinical outcome and recurrence rates after tumor removal through the frontolateral and bifrontal approach. Neurosurgery 62:6 Suppl 31224–1232, 2008
4)

Pepper J, Hecht SL, Gebarski SS, Lin EM, Sullivan SE, Marentette LJ. Olfactory groove meningioma: discussion of clinical presentation and surgical outcomes following excision via the subcranial approach. Laryngoscope. 2011;121:2282–2289.
5)

Purohit A, Jha R, Khalafallah AM, Price C, Rowan NR, Mukherjee D. Endoscopic endonasal versus transcranial approach to resection of olfactory groove meningiomas: a systematic review. Neurosurg Rev. 2020 Dec;43(6):1465-1471. doi: 10.1007/s10143-019-01193-2. Epub 2019 Nov 10. PMID: 31709465.
6)

Feng AY, Wong S, Saluja S, Jin MC, Thai A, Pendharkar AV, Ho AL, Reddy P, Efron AD. Resection of Olfactory Groove Meningiomas Through Unilateral vs. Bilateral Approaches: A Systematic Review and Meta-Analysis. Front Oncol. 2020 Oct 22;10:560706. doi: 10.3389/fonc.2020.560706. PMID: 33194626; PMCID: PMC7642686.
7)

Shetty SR, Ruiz-Treviño AS, Omay SB, Almeida JP, Liang B, Chen YN, Singh H, Schwartz TH. Limitations of the endonasal endoscopic approach in treating olfactory groove meningiomas. A systematic review. Acta Neurochir (Wien). 2017 Oct;159(10):1875-1885. doi: 10.1007/s00701-017-3303-0. Epub 2017 Aug 22. PMID: 28831590.