Intracranial dermoid cyst

Intracranial dermoid cyst

Intracranial dermoid cysts generally occur along the midline and are derived from the trapped somatic ectoderm during embryological development during third to fifth week of gestation.

The tumors typically arise in infants to young adults because of their congenital origin 1) 2) 3). Intracranial dermoid cyst are very rare, constituting less than 1% of intracranial tumor4), and are relatively rare in middle-aged or older people 5).

Many reports have mentioned the intradural posterior fossa and the midline as the preferential localization of these tumors 6) 7). In contrast, extradural dermoid cysts are a much rarer entity 8) 9).

see Parasellar dermoid cyst.

see Posterior fossa dermoid cyst.

see Asterional dermoid cyst.

Dermoid cysts are thought to occur as a developmental anomaly in which embryonic ectoderm is trapped in the closing neural tube between the 5th-6th weeks of gestation.

Dermoid cysts, like epidermoid cysts, are lined by stratified squamous epithelium. Unlike epidermoid cysts, however, they also have epidermal appendages such as hair follicles, sweat and sebaceous glands. The latter handles the secretion of sebum that imparts the characteristic appearance of these lesions on CT and MRI.

A common misconception is that dermoid cysts contain adipose tissue. This is not the case, as lipocytes are mesodermal in origin, and dermoid cysts (by definition) are purely ectodermal. A dermoid cyst with adipose tissue would be a teratoma.

Associated dermal sinuses cause earlier onset of clinical symptoms such as infection 10). Other common symptoms including headaches, seizures, and chemical meningitis, and visual disturbances occur late in the clinical course because of its slow-growing nature 11) 12) 13).

Many intracranial dermoid cysts are asymptomatic and only found incidentally. Often there is a long history of vague symptoms, with headache being a prominent feature

In case of rupture (spontaneous, traumatic, or iatrogenic (at resection)) leakage of sebum into the subarachnoid space results in an aseptic chemical meningitis.

The presentation is variable, ranging from a headache, to seizures, vasospasm and even death 14).

Occasionally, dermoid tumors are incidentally discovered on computed tomography (CT) of the brain or magnetic resonance imaging (MRI) following unrelated clinical complaints. They are also discovered during radiologic investigations of unexplained headaches, seizures, and rarely olfactory delusions.

On imaging, they are usually well-defined lobulated midline masses that have low attenuation (fat density) on CT and hypersignal on T1-weighted MRI images. Typically they do not enhance after contrast administration.

Although dermoid cysts are pathognomonic in appearance on a CT examination, the MRI is also of value in helping to understand the effect of extension and pressure of the mass. DWI is also important for support of the diagnosis and patient follow-up.


Historically, when skull x-rays were routinely used in the assessment of suspected intracranial pathology, a focal lucency due to the fatty sebum


Typically dermoid cysts appear as well defined low attenuating (fat density) lobulated masses. Calcifications may be present in the wall. Enhancement is uncommon, and if present should at most be a thin peripheral rim.

Very rarely they demonstrate hyperdensity thought to be due to a combination of saponification, microcalcification and blood products. This is usually the case when present in the posterior fossa, although why this is the case is not certain.


Unlike intracranial lipomas that follow fat density on all sequences, intracranial dermoids have more variable signal characteristics:

T1 typically hyperintense (due to cholesterol components) droplets in the subarachnoid space may be visible if rupture has occurred

T1 C+ (Gd): generally do not enhance extensive pial enhancement may be present in chemical meningitis caused by ruptured cysts

T2: variable signal ranging from hypo to hyperintense.


Left parasellar extraaxial lesion 2.2 x 1.9 x 1.5 cm without evidence of contrast uptake.

Slight mass effect on the anterior aspect of the left temporal lobe.

Epidermoid cysts at one end (containing only desquamated squamous epithelium) and teratomas at the other (containing essentially any kind of tissue from all three embryonic tissue layers).

Intracranial lipoma: homogeneous fat attenuation/signal intensity, chemical shift artefact

Intracranial teratoma: immature, usually occur in the pineal region

Craniopharyngioma most are strikingly hyperintense on T2, most enhance strongly

Can be surgically excised and provided complete excision is achieved recurrence is uncommon. Sometimes due to local adhesion of the capsule to vital structures, incomplete excision must be performed. Recurrent growth, in either case, is slow 15).

Spontaneous rupture of dermoid tumor is a potentially serious complication that can lead to meningitis, seizures, cerebral ischemia and hydrocephalus.

Rupture of these benign lesions occurs in only a small percentage of patients, and usually occurs spontaneously 16) 17)

Traumatic rupture of an intracranial dermoid cyst is an exceedingly rare event, with only three cases reported in the literature to date 18) 19) 20).

Extremely rare malignant transformation into squamous cell carcinoma has been reported 21).

Intracranial dermoid cyst case reports.

1) , 11)

Akdemir G, Dağlioğlu E, Ergüngör M F. Dermoid lesion of the cavernous sinus: case report and review of the literature. Neurosurg Rev. 2004;27:294–298.
2) , 12)

Lunardi P, Missori P. Supratentorial dermoid cysts. J Neurosurg. 1991;75:262–266.
3) , 10)

Caldarelli M Massimi L Kondageski C Di Rocco C Intracranial midline dermoid and epidermoid cysts in children J Neurosurg 2004100(5 Suppl Pediatrics):473–480.480
4) , 6)

Guidetti B, Gagliardi F M. Epidermoid and dermoid cysts. Clinical evaluation and late surgical results. J Neurosurg. 1977;47:12–18.
5) , 8)

Ammirati M, Delgado M, Slone H W, Ray-Chaudhury A. Extradural dermoid tumor of the petrous apex. Case report. J Neurosurg. 2007;107:426–429.

Bogdanowicz W M, Wilson D H. Dermoid cyst of the fourth ventricle demonstrated on brain scan. Case report. J Neurosurg. 1972;36:228–230.

Blythe J N, Revington P J, Nelson R. Anterior cranial fossa dermoid cyst: case report. Br J Oral Maxillofac Surg. 2007;45:661–663.

Rubin G, Scienza R, Pasqualin A, Rosta L, Da Pian R. Craniocerebral epidermoids and dermoids. A review of 44 cases. Acta Neurochir (Wien) 1989;97:1–16.

Brown JY, Morokoff AP, Mitchell PJ, Gonzales MF. Unusual imaging appearance of an intracranial dermoid cyst. AJNR Am J Neuroradiol. 2001 Nov-Dec;22(10):1970-2. PubMed PMID: 11733334.

Yaşargil MG. Microneurosurgery IV/B, Microsurgery of CNS Tumors. (1996) ISBN:3131165014

El-Bahy K, Kotb A, Galal A, El-Hakim A. Ruptured intracranial dermoid cysts. Acta Neurochir (Wien) 2006;148:457–62.

Stendel R, Pietila TA, Lehmann K, Kurth R, Suess O, Brock M. Ruptured intracranial dermoid cysts. Surg Neurol. 2002;57:391–8.

Kim IY, Jung S, Jung TY, Kang SS, Kim TS. Traumatic rupture of an intracranial dermoid cyst. J Clin Neurosci. 2008;15:469–71.

Park SK, Cho KG. Recurrent intracranial dermoid cyst after subtotal removal of traumatic rupture. Clin Neurol Neurosurg. 2012;114:421–4.

Phillips WE, 2nd, Martinez CR, Cahill DW. Ruptured intracranial dermoid tumor secondary to closed head trauma. Computed tomography and magnetic resonance imaging. J Neuroimaging. 1994;4:169–70

Osborn AG, Preece MT. Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology. 2006 Jun;239(3):650-64. Review. PubMed PMID: 16714456.

Unruptured intracranial aneurysm treatment score

Unruptured intracranial aneurysm treatment score

see also PHASES score.

The unruptured intracranial aneurysm treatment score (UIATS) was published in April 2015 as a multidisciplinary consensus regarding the treatment of unruptured intracranial aneurysms (UIA).

Etminan et al. endeavored to develop an unruptured intracranial aneurysm treatment score (UIATS) model that includes and quantifies key factors involved in clinical decision-making in the management of UIAs and to assess agreement for this model among specialists in Unruptured intracranial aneurysm (UIA) management and research.

An international multidisciplinary (neurosurgery, neuroradiology, neurology, clinical epidemiology) group of 69 specialists was convened to develop and validate the UIATS model using a Delphi consensus. For internal (39-panel members involved in the identification of relevant features) and external validation (30 independent external reviewers), 30 selected UIA cases were used to analyze agreement with UIATS management recommendations based on a 5-point Likert scale (5 indicating strong agreement). Interrater agreement (IRA) was assessed with standardized coefficients of dispersion (vr) (vr = 0 indicating excellent agreement and vr* = 1 indicating poor agreement).

The UIATS accounts for 29 key factors in UIA management. Agreement with UIATS (mean Likert scores) was 4.2 (95% confidence interval [CI] 4.1-4.3) per reviewer for both reviewer cohorts; agreement per case was 4.3 (95% CI 4.1-4.4) for panel members and 4.5 (95% CI 4.3-4.6) for external reviewers (p = 0.017). Mean Likert scores were 4.2 (95% CI 4.1-4.3) for interventional reviewers (n = 56) and 4.1 (95% CI 3.9-4.4) for noninterventional reviewers (n = 12) (p = 0.290). Overall IRA (vr*) for both cohorts was 0.026 (95% CI 0.019-0.033).

This novel UIA decision guidance study captures an excellent consensus among highly informed individuals on UIA management, irrespective of their underlying specialty. Clinicians can use the UIATS as a comprehensive mechanism for indicating how a large group of specialists might manage an individual patient with a UIA 1)   

The Unruptured Intracranial Aneurysm Treatment Score (UIATS) offers support for clinical decision making and has been shown to correlate with real-life decisions in clinical practice. However, there is no data concerning the correlation of patient Unruptured intracranial aneurysm outcome and UIATS. Patients presenting to the Department of Neurosurgery,University Hospital Leipzig, outpatient clinic between January 1st, 2014, and December 31st, 2017 were retrospectively analyzed. They recorded the Extended Glasgow Outcome Scale (GOS-E) for the longest possible follow-up, the choice of treatment, complications, and UIATS recommendation. They included 221 patients with 322 UIA. 124 (38.5 %) UIA were observed and 198 (61.5 %) were occluded, of which 62 (31.3 %) underwent open surgery and 136 (68.7 %) were treated endovascularly. Spearman’s rank correlation between the treatment choice and conclusive UIATS recommendation was 0.362 (p < 0.001). If UIATS was inconclusive, there were significantly more treatment-associated deteriorations (10/66 versus 7/132, p = 0.020). Otherwise, UIATS was not significantly associated with outcome. Therefore, the treatment choice for UIA remains an individual decision. However, inconclusive UIATS must trigger vigilance and may be a negative prognostic marker for complications 2).

A tertiary center with focus on vascular neurosurgery, aimed to investigate whether there treatment decision-making in patients with UIA has been in accordance with the published UIATS. A retrospective analysis of patients admitted to the center with UIA was performed. UIATS was applied to all identified UIA. Three decision groups were defined: (a) UIATS favoring treatment, (b) UIATS favoring observation, and © UIATS inconclusive. These results were then compared to our clinical decisions. Spearman’s rank-order correlation (ρ) was run to determine the relationship between the UIATS and our clinical decisions. Cases of discrepancies between UIATS and our clinical decisions were then examined for complications, defined as periprocedural adverse events in treated aneurysms, or aneurysm rupture in untreated aneurysms. Ninety-three patients with 147 UIA were included. A total of 118/147 (80.3%) UIA were treated. In 70/118 (59.3%), UIATS favored treatment, in 18/118 (15.3%), it was inconclusive, and in 30/118 (25.4%), it favored observation. A total of 29/147 (19.7%) UIA were not treated. In 15/29 (51.7%), UIATS favored observation, in 9/29 (31%), it favored treatment, and in 5/29 (17.2%), it was inconclusive (ρ = 0.366, p < 0.01). Discrepancies between UIATS and our clinical decisions did not correlate with complications (ρ = 0.034, p = 0.714). Our analysis shows that our more intuitive clinical decision-making has been in line with UIATS. Our treatment decisions did not correlate with an increased rate of complications 3).

The purpose of the study of Ravindra et al. was to compare the unruptured intracranial aneurysm treatment score (UIATS) recommendations with the real-world experience in a quaternary academic medical center with a high volume of patients with unruptured intracranial aneurysms (UIAs).

All patients with UIAs evaluated during a 3-year period were included. All factors included in the UIATS were abstracted, and patients were scored using the UIATS. Patients were categorized in a contingency table assessing UIATS recommendation versus real-world treatment decision. The authors calculated the percentage of misclassification, sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve. RESULTS A total of 221 consecutive patients with UIAs met the inclusion criteria: 69 (31%) patients underwent treatment and 152 (69%) did not. Fifty-nine (27%) patients had a UIATS between -2 and 2, which does not offer a treatment recommendation, leaving 162 (73%) patients with a UIATS treatment recommendation. The UIATS was significantly associated with treatment (p < 0.001); however, the sensitivity, specificity, and percentage of misclassification were 49%, 80%, and 28%, respectively. Notably, 51% of patients for whom treatment would be recommended by the UIATS did not undergo treatment in the real-world cohort and 20% of patients for whom conservative management would be recommended by UIATS had intervention. The area under the ROC curve was 0.646.

Compared with the authors’ experience, the UIATS recommended overtreatment of UIAs. Although the UIATS could be used as a screening tool, individualized treatment recommendations based on consultation with a cerebrovascular specialist are necessary. Further validation with longitudinal data on rupture rates of UIAs is needed before widespread use 4).


Etminan N, Brown RD Jr, Beseoglu K, Juvela S, Raymond J, Morita A, Torner JC, Derdeyn CP, Raabe A, Mocco J, Korja M, Abdulazim A, Amin-Hanjani S, Al-Shahi Salman R, Barrow DL, Bederson J, Bonafe A, Dumont AS, Fiorella DJ, Gruber A, Hankey GJ, Hasan DM, Hoh BL, Jabbour P, Kasuya H, Kelly ME, Kirkpatrick PJ, Knuckey N, Koivisto T, Krings T, Lawton MT, Marotta TR, Mayer SA, Mee E, Pereira VM, Molyneux A, Morgan MK, Mori K, Murayama Y, Nagahiro S, Nakayama N, Niemelä M, Ogilvy CS, Pierot L, Rabinstein AA, Roos YB, Rinne J, Rosenwasser RH, Ronkainen A, Schaller K, Seifert V, Solomon RA, Spears J, Steiger HJ, Vergouwen MD, Wanke I, Wermer MJ, Wong GK, Wong JH, Zipfel GJ, Connolly ES Jr, Steinmetz H, Lanzino G, Pasqualin A, Rüfenacht D, Vajkoczy P, McDougall C, Hänggi D, LeRoux P, Rinkel GJ, Macdonald RL. The unruptured intracranial aneurysm treatment score: a multidisciplinary consensus. Neurology. 2015 Sep 8;85(10):881-9. doi: 10.1212/WNL.0000000000001891. Epub 2015 Aug 14. PubMed PMID: 26276380; PubMed Central PMCID: PMC4560059.

Wende T, Kasper J, Wilhemy F, Prasse G, Quäschling U, Haase A, Meixensberger J, Nestler U. Comparison of the unruptured intracranial aneurysm treatment score recommendations with clinical treatment results – A series of 322 aneurysms. J Clin Neurosci. 2022 Feb 9;98:104-108. doi: 10.1016/j.jocn.2022.01.038. Epub ahead of print. PMID: 35151060.

Hernández-Durán S, Mielke D, Rohde V, Malinova V. The application of the unruptured intracranial aneurysm treatment score: a retrospective, single-center study. Neurosurg Rev. 2018 Feb 1. doi: 10.1007/s10143-018-0944-2. [Epub ahead of print] PubMed PMID: 29388120.

Ravindra VM, de Havenon A, Gooldy TC, Scoville J, Guan J, Couldwell WT, Taussky P, MacDonald JD, Schmidt RH, Park MS. Validation of the unruptured intracranial aneurysm treatment score: comparison with real-world cerebrovascular practice. J Neurosurg. 2017 Oct 6:1-7. doi: 10.3171/2017.4.JNS17548. [Epub ahead of print] PubMed PMID: 28984518.

Intracranial aneurysm clipping

Intracranial aneurysm clipping

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 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.

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve patient outcomes.

In the US, a number of training programs are including 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 2).

Time from rupture to treatment is a crucial factor in determining outcome.

Practice of delayed surgery to avoid edematous brain has been replaced by early surgery to minimize risk from rebleeding and vasospasm. Mahaney et al. in their analysis of intraoperative hypothermia for aneurysm surgery trial (IHAST) data observed that patients operated early (day 0-2) or late (day 7-14) fared significantly better than those operated during intermediate phase (day 3-6). Change in surgical strategy has posed challenge to the anesthesiologists as increasing number of patients are operated during off-work hours in inadequately optimized state with less expert help.

Nieuwkamp et al., performed a retrospective observational study on the timing of intracranial aneurysm surgery in The Netherlands over a two-year period.

In eight hospitals they identified 1,500 patients with an aneurysmal subarachnoid hemorrhage. They were subjected to predefined inclusion criteria. They included all patients who were admitted and were conscious at any one time between admission and the end of the third day after the haemorrhage. We categorised the clinical condition on admission according the World Federation of Neurological Surgeons (WFNS) grading scale. Early aneurysm surgery was defined as operation performed within three days after onset of subarachnoid haemorrhage; intermediate surgery as performed on days four to seven, and late surgery as performed after day seven. Outcome was classified as the proportion of patients with poor outcome (death or dependent) two to four months after onset of subarachnoid haemorrhage. We calculated crude odds ratios with late surgery as reference. We distinguished between management results (reconstructed intention to treat analysis) and surgical results (on treatment analysis). The results were adjusted for the major prognosticators for outcome after subarachnoid haemorrhage.

They included 411 patients. There were 276 patients in the early surgery group, 36 in the intermediate surgery group and 99 in the late surgery group. On admission 78% were in good neurological condition (WFNS I-III). MANAGEMENT

Overall, 93 patients (34%) operated on early had a poor outcome, 13 (36%) of those with intermediate surgery and 37 (37%) in the late surgery group had a poor outcome. For patients in good clinical condition on admission and planned for early surgery the adjusted odds ratio (OR) was 1.3 (95% CI 0.5 to 3.0). The adjusted OR for patients admitted in poor neurologicalcondition (WFNS IV-V) and planned for early surgery was 0.1 (95% CI 0.0 to 0.6). SURGICAL RESULTS: For patients in good clinical condition on admission who underwent early operation the adjusted OR was 1.1 (95% CI 0.4 to 3.2); it was 0.2 (95% CI 0.0 to 0.9) for patients admitted in poor clinical condition.

In this observational study they found no significant difference in outcome between early and late operation for patients in good clinical condition on admission. For patients in poor clinical condition on admission outcome was significantly better after early surgery. The optimal timing of surgery is not yet settled. Ideally, evidence on this issue should come from a randomised clinical trial. However, such a trial or even a prospective study are unlikely to be ever performed because of the rapid development of endovascular coiling 3).

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. 4).

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.

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

see Endoscopic endonasal approach for intracranial aneurysm

see Surgical clipping versus endovascular coiling for intracranial aneurysm

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. 5).

Pterional approach via standard frontotemporal craniotomy and interhemispheric approach via bifrontal craniotomy is the gold standard for clipping of cerebral aneurysms in the anterior circulationEndovascular 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).

see Intracranial aneurysm clipping complications.

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).

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).

The mechanisms underlying neurocognitive changes after surgical clipping of unruptured intracranial aneurysms (UIAs) are poorly understood.

Minimal structural damage visualized on T2-weighted images at 6 months as a result of factors such as pial/microvascular injury and excessive retraction during surgical manipulation could cause subtle but significant negative effects on postoperative neurocognitive function after surgical clipping of a UIA. However, this detrimental effect was small, and based on the group-rate analysis

Successful and meticulous surgical clipping of a UIA does not adversely affect postoperative cognitive function 12).

Results of treatment after clipping and coiling do not differ in total for all patients, but differ depending on the presence of bleeding. Patients with bleeding aneurysms achieve better outcomes after coiling, and patients with non-bleeding aneurysms achieve better outcomes after clipping 13).

Risk of ischemia during intracranial aneurysm surgery is significantly related to temporary clipping time and final clipping that might incorporate a perforator.

Abdulrauf et al. attempted to assess the potential added benefit to patient outcomes of “awake” neurological testing when compared with standard neurophysiological testing performed under general anesthesia. The procedure is performed after the induction of conscious sedation, and for the neurological testing, the patient is fully awake.

They conducted an institutional review board-approved prospective study of clipping unruptured intracranial aneurysms (UIAs) in 30 consecutive adult patients who underwent awake clipping. The end points were the incidence of stroke/cerebrovascular accident (CVA), death, discharge to a long-term facility, length of stay, and 30-day modified Rankin Scale score. All clinical and neurophysiological intraoperative monitoring data were recorded.

The median patient age was 52 years (range 27-63 years); 19 (63%) female and 11 (37%) male patients were included. Twenty-seven (90%) aneurysms were anterior, and 3 (10%) were posterior circulation aneurysms. Five (17%) had been coiled previously, 3 (10%) had been clipped previously, 2 (7%) were partially calcified, and 2 (7%) were fusiform aneurysms. Three patients developed synchronous clinical neurological and neurophysiological changes during temporary clipping with consequent removal of the temporary clip and reversal of those clinical and neurophysiological changes. Three patients developed asynchronous clinical neurological and neurophysiological changes. These 3 patients developed hemiparesis without changes in neurophysiological monitoring results. One patient developed linked clinical neurological and neurophysiological changes during final clipping that were not reversed by reapplication of the clip, and the patient had a CVA. Four patients with internal carotid artery ophthalmic segment aneurysms underwent visual testing with final clipping, and 1 of these patients required repositioning of the clip. Three patients who required permanent occlusion of a vessel as part of their aneurysm treatment underwent a 10-minute intraoperative clinical respective-vessel test occlusion. The median length of stay was 3 days (range 1-5 days). The median modified Rankin Scale score was 1 (range 0-3). All of the patients were discharged to home from the hospital except for 1 who developed a CVA and was discharged to a rehabilitation facility. There were no deaths in this series.

The 3 patients who developed neurological deterioration without a concomitant neurophysiological finding during temporary clipping revealed a potential advantage of awake aneurysm surgery (i.e., in decreasing the risk of ischemic injury) 14).

see Virtual reality simulator for aneurysmal clipping surgery.

A total of 53 patients from Phoenix and San Francisco, who initially presented with a subarachnoid hemorrhage and underwent surgical clipping of a previously coiled intracranial aneurysm between December 1997 and December 2014 were studied. Clinical features, hospital course, and preoperative and most recent functional status (Glasgow Outcome Scale score) were reviewed retrospectively.

The mean time interval from coiling to clipping was 2.6 years, and mean follow-up was 5.5 years (range, 0.1-14.7 years). Five patients (9.8%) presented with rebleed prior to clipping. Most patients (79.3%, 42/53) experienced good neurologic outcomes. Most showed no change (81%, 43/53) or improvement (13%, 7/53) in functional status after microsurgical clipping. One patient (2%) deteriorated clinically, and there were 2 mortalities (4%).

Microsurgical clipping of previously ruptured, coiled aneurysms is a promising treatment method with favorable clinical outcomes 15).

Retrospective review of the medical records of 320 patients with 416 aneurysms treated with microsurgical clipping from 2008 to 2016 in a single neurosurgical center in Brazil. This study evaluated postoperative outcome, using the modified Rankin Scale (mRS) on hospital discharge, treatment efficacy, assessed by digital subtraction angiography (DSA) performed postoperatively, and mortality.

Among 320 patients with aneurysms, 228 patients presented with ruptured aneurysms and 92 patients with unruptured aneurysms. Overall, 81 (26,3%) presented poor outcome (mRs>2) while 227 (73,4%) showed good outcome. The presence of a ruptured aneurysm was a statistically significant factor for poor outcome (p<0,001) and mortality (p<0,015). Giant and large aneurysms were also associated with poor outcome (p=0,004). When we analyze separately, unruptured aneurysms with poor outcome were only associated with aneurysms size. Among the patients with ruptured aneurysms, those with Hunt Hess (HH) > 2 on hospital admission showed unfavorable outcomes (p<0,0001). Among patients submitted to postoperative DSA, 207 (89,8%) had complete occlusion of the aneurysms and 24 (10,2%) presented residual aneurysms, with reoperation required in eight cases.

Microsurgical treatment of intracranial aneurysms is an effective and safe method 16).


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