Category: Vascular

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Terson syndrome in aneurysmal subarachnoid hemorrhage

Terson syndrome

Acta Neurochir (2016) 158:1027–1036

A large number of reports have not been able to clarify the pathophysiology of Terson syndrome (TS) in aneurysmal subarachnoid hemorrhage (aSAH).

Methods Prospective single-center study on aSAH patients. Fundoscopic and radiological signs of TS were assessed. The opening intracranial pressure (ICP) in patients who required a ventriculostomy was recorded with a manometer.

Results Six out of 36 included patients had TS (16.7 %), which was associated with unfavorable admission scores. Twenty-nine patients (80.5 %) required ventriculostomy; TS was associated with higher ICP (median, 40 vs. 15 cm cmH2O, p= .003); all patients with TS had pathological ICP values of >20 cmH2O. Patients with a ruptured aneurysm of the anterior cerebral artery complex were ten times as likely to suffer from TS (OR 10.0, 95 % CI 1.03–97.50). Detection of TS on CT had a sensitivity of 50 %, a specificity of 98.4 %, a positive predictive value of 83.3 %, and a negative predictive value of 92.4 %. Mortality was 45 times as high in patients with TS (OR 45.0, 95 % CI 3.86–524.7) and neurologic morbidity up until 3 months post-aSAH was significantly higher in patients with TS (mRS 4–6; 100 vs. 17 %; p = .001).

Conclusions Our findings demonstrate an association between raised ICP and the incidence of TS. TS should be ruled out in aSAH patients presenting comatose or with raised ICP to ensure upfront ophthalmological follow-up. In alert patients without visual complaints and a TS-negative CT scan, the likelihood for the presence of TS is very low.

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Is systematic post-operative CT scan indicated after chronic subdural hematoma surgery?

Is systematic post-operative CT scan indicated after chronic subdural hematoma surgery?

Acta Neurochir (2016) 158:1241–1246

The aim of the present study was to evaluate the interest of systematic post-operative CTscan after unilateral chronic subdural hematoma (CSDH) evacuation. To achieve this goal, we chose to evaluate the ability of postoperative CT scan to predict the most frequent complication of CSDH: hematoma recurrence.

Methods We performed a retrospective case–control study. Cases were defined as patients who had CSDH recurrence; controls were those who did not.We first studied clinical data and pre-operative CT scan data. We then studied postoperative CT scan data: hematoma thickness and its decrease, persistence of midline shift, its value and its decrease, and presence of compressive pneumocephalus.

Results Among 654 patients, 15 were defined as cases, and were matched with 30 non-recurrent patients defined as controls. Regarding systematic post-operative CT scan findings, unilateral CSDH recurrence was clearly associated with the persistence of midline shift induced by the presence of compressive pneumocephalus.

Conclusions Systematic post-operative CT scan after unilateral CSDH evacuation could predict hematoma recurrence. We therefore considered it as recommended, to adapt the clinical and radiological follow-up of CSDH patients.

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Dural arteriovenous fistula–induced thalamic dementia

Thalamic DAVF

J Neurosurg 124:1752–1765, 2016

Nonhemorrhagic neurological deficits are underrecognized symptoms of intracranial dural arteriovenous fistulas (dAVFs) having cortical venous drainage. These symptoms are the consequence of cortical venous hypertension and portend a clinical course with increased risk of neurological morbidity and mortality. One rarely documented and easily misinterpreted type of nonhemorrhagic neurological deficit is progressive dementia, which can result from venous hypertension in the cortex or in bilateral thalami. The latter, which is due to dAVF drainage into the deep venous system, is the less common of these 2 dementia syndromes.

Herein, the authors report 4 cases of dAVF with venous drainage into the vein of Galen causing bithalamic edema and rapidly progressive dementia. Two patients were treated successfully with endovascular embolization, and the other 2 patients were treated successfully with endovascular embolization followed by surgery. The radiographic abnormalities and presenting symptoms rapidly resolved after dAVF obliteration in all 4 cases. Detailed descriptions of these 4 cases are presented along with a critical review of 15 previously reported cases.

In our analysis of these 19 published cases, the following were emphasized: 1) the clinical and radiographic differences between dAVF-induced thalamic versus cortical dementia syndromes; 2) the differential diagnosis and necessary radiographic workup for patients presenting with a rapidly progressive thalamic dementia syndrome; 3) the frequency at which delays in diagnosis occurred and potentially dangerous and avoidable diagnostic procedures were used; and 4) the rapidity and completeness of symptom resolution following dAVF treatment.

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Decompressive hemicraniectomy: predictors of functional outcome in patients with ischemic stroke

Decompressive hemicraniectomy

J Neurosurg 124:1773–1779, 2016

Patients presenting with large-territory ischemic strokes may develop intractable cerebral edema that puts them at risk of death unless intervention is performed. The purpose of this study was to identify predictors of outcome for decompressive hemicraniectomy (DH) in ischemic stroke.

Methods: The authors conducted a retrospective electronic medical record review of 1624 patients from 2006 to 2014. Subjects were screened for DH secondary to ischemic stroke involving the middle cerebral artery, internal carotid artery, or both. Ninety-five individuals were identified. Univariate and multivariate analyses were performed for an array of clinical variables in relationship to functional outcome according to the modified Rankin Scale (mRS). Clinical outcome was assessed at 90 days and at the latest follow-up (mean duration 16.5 months).

Results: The mean mRS score at 90 days and at the latest follow-up post-DH was 4. Good functional outcome was observed in 40% of patients at 90 days and in 48% of patient at the latest follow-up. The mortality rate at 90 days was 18% and at the last follow-up 20%. Univariate analysis identified a greater likelihood of poor functional outcome (mRS scores of 4–6) in patients with a history of stroke (OR 6.54 [95% CI 1.39–30.66]; p = 0.017), peak midline shift (MLS) > 10 mm (OR 3.35 [95% CI 1.33–8.47]; p = 0.011), or a history of myocardial infarction (OR 8.95 [95% CI 1.10–72.76]; p = 0.04). Multivariate analysis demonstrated elevated odds of poor functional outcome associated with a history of stroke (OR 9.14 [95% CI 1.78–47.05]; p = 0.008), MLS > 10 mm (OR 5.15 [95% CI 1.58–16.79; p = 0.007), a history of diabetes (OR 5.63 [95% CI 1.52–20.88]; p = 0.01), delayed time from onset of stroke to DH (OR 1.32 [95% CI 1.02–1.72]; p = 0.037), and evidence of pupillary dilation prior to DH (OR 4.19 [95% CI 1.06–16.51]; p = 0.04). Patients with infarction involving the dominant hemisphere had higher odds of unfavorable functional outcome at 90 days (OR 4.73 [95% CI 1.36–16.44]; p = 0.014), but at the latest follow-up, cerebral dominance was not significantly related to outcome (OR 1.63 [95% CI 0.61–4.34]; p = 0.328).

Conclusions: History of stroke, diabetes, myocardial infarction, peak MLS > 10 mm, increasing duration from onset of stroke to DH, and presence of pupillary dilation prior to intervention are associated with a worse functional outcome.

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Factors Associated With Proximal Intracranial Aneurysms to Brain Arteriovenous Malformations

Factors Associated With Proximal Intracranial Aneurysms to Brain Arteriovenous Malformations

Neurosurgery 78:787–792, 2016

The risk of hemorrhage from a brain arteriovenous malformation (bAVM) is increased when an associated proximal intracranial aneurysm (APIA) is present. Identifying factors that are associated with APIA may influence the prediction of hemorrhage in patients with bAVM.

OBJECTIVE: To identify patient- and bAVM-specific factors associated with APIA.

METHODS: We analyzed a prospective database of bAVMs for factors associated with the presence of APIA. Factors analyzed included age, sex, bAVM size, aneurysm size, circulation contributing to the bAVM, location of the aneurysm, deep venous drainage, and Spetzler-Ponce categories. Multiple logistic regression was performed to identify an association with APIA.

RESULTS: Of 753 cases of bAVM with complete angiographic surveillance, 67 (9%) were found to have APIA. Older age (continuous variable; odds ratio, 1.04; 95% confidence interval, 1.02-1.05) and posterior circulation supply to the bAVM (odds ratio, 2.29; 95% confidence interval, 1.32-3.99) were factors associated with increased detection of APIA. The association of posterior circulation–supplied bAVM was not due to infratentorial bAVM location because 72% of posterior circulation APIAs were supplying supratentorial bAVM.

CONCLUSION: APIAs appear to develop with time, as evident from the increased age for those with APIAs. Furthermore, they were more likely present in bAVMs supplied by the posterior circulation. This may be due to a difference in hemodynamic stress.

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Predictors of aneurysmal rebleed before definitive surgical or endovascular management

A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography- Beyond the Fisher Scale

Acta Neurochir (2016) 158:1037–1044

Aneurysmal rebleed is the most dreaded complication following subarachnoid hemorrhage. Being a cause of devastating outcome, the stratification of risk factors can be used to prioritize patients, especially at high volume centers.

Method: A total of 99 patients with aneurysmal rebleed were analyzed in this study both prospectively and retrospectively from August 2010 to July 2014. In the control group, 100 patients were selected randomly from the patient registry. A total of 25 variables from the demographic, historical, clinical and radiological data were compared and analyzed by univariate and multivariate logistic regression analysis.

Results: Significant independent predictors of aneurysm rebleed were the presence of known hypertension (p=0.023), diastolic blood pressure of >90 mmHg on admission (p=0.008); presence of loss of consciousness (p= 0.013) or seizures (p = 0.002) at first ictus; history of warning headaches (p=0.005); higher Fisher grade (p<0.001); presence of multiple aneurysms (p= 0.021); irregular aneurysm surface (0.002).

Conclusions: Identification of high risk factors can help in stratifying patients in the high risk group. The risk stratification strategy with early intervention can prevent rebleeds. This in turn may translate into better outcomes of patients with intracranial aneurysms.

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Intracranial-to-intracranial bypass for posterior inferior cerebellar artery aneurysms

Intracranial-to-intracranial bypass for posterior inferior cerebellar artery aneurysms

J Neurosurg 124:1275–1286, 2016

Intracranial-to-intracranial (IC-IC) bypasses are alternatives to traditional extracranial-to-intracranial (ECIC) bypasses to reanastomose parent arteries, reimplant efferent branches, revascularize branches with in situ donor arteries, and reconstruct bifurcations with interposition grafts that are entirely intracranial. These bypasses represent an evolution in bypass surgery from using scalp arteries and remote donor sites toward a more local and reconstructive approach. IC-IC bypass can be utilized preferentially when revascularization is needed in the management of complex aneurysms. Experiences using IC-IC bypass, as applied to posterior inferior cerebellar artery (PICA) aneurysms in 35 patients, were reviewed.

Methods: Patients with PICA aneurysms and vertebral artery (VA) aneurysms involving the PICA’s origin were identified from a prospectively maintained database of the Vascular Neurosurgery Service, and patients who underwent bypass procedures for PICA revascularization were included.

Results: During a 17-year period in which 129 PICA aneurysms in 125 patients were treated microsurgically, 35 ICIC bypasses were performed as part of PICA aneurysm management, including in situ p3-p3 PICA-PICA bypass in 11 patients (31%), PICA reimplantation in 9 patients (26%), reanastomosis in 14 patients (40%), and 1 V3 VA-to-PICA bypass with an interposition graft (3%). All aneurysms were completely or nearly completely obliterated, 94% of bypasses were patent, 77% of patients were improved or unchanged after treatment, and good outcomes (modified Rankin Scale ≤ 2) were observed in 76% of patients. Two patients died expectantly. Ischemic complications were limited to 2 patients in whom the bypasses occluded, and permanent lower cranial nerve morbidity was limited to 3 patients and did not compromise independent function in any of the patients.

Conclusions: PICA aneurysms receive the application of IC-IC bypass better than any other aneurysm, with nearly one-quarter of all PICA aneurysms treated microsurgically at our center requiring bypass without a single EC-IC bypass. The selection of PICA bypass is almost algorithmic: trapped aneurysms at the PICA origin or p1 segment are revascularized with a PICA-PICA bypass, with PICA reimplantation as an alternative; trapped p2 segment aneurysms are reanastomosed, bypassed in situ, or reimplanted; distal p3 segment aneurysms are reanastomosed or revascularized with a PICA-PICA bypass; and aneurysms of the p4 segment that are too distal for PICA-PICA bypass are reanastomosed. Interposition grafts are reserved for when these 3 primary options are unsuitable. A constructive approach that preserves the PICA with direct clipping or replaces flow with a bypass when sacrificed should remain an alternative to deconstructive PICA occlusion and endovascular coiling when complete aneurysm occlusion is unlikely.

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Outcomes of Multimodality Therapy in Pediatric Patients With Ruptured and Unruptured Brain Arteriovenous Malformations

Outcomes of Multimodality Therapy in Pediatric Patients With Ruptured and Unruptured Brain Arteriovenous Malformations

Neurosurgery 78:695–707, 2016

Brain arteriovenous malformations (BAVMs) are a frequent cause of pediatric hemorrhagic stroke, which frequently results in significant morbidity and mortality.

OBJECTIVE: To analyze the results of multimodality treatment for a consecutive series of pediatric patients with ruptured and unruptured BAVMs at a single institution.

METHODS: Forty patients ,18 years of age were retrospectively reviewed. Results were divided by hemorrhage status, ie, ruptured or unruptured, and the intended curative treatment modality, ie, surgical resection or stereotactic radiosurgery.

RESULTS: Twenty-seven patients (68%) presented with hemorrhage, and 13 patients (32%) presented without hemorrhage. Among ruptured patients, 19 (70%) underwent surgery and 8 (30%) underwent stereotactic radiosurgery. In surviving patients who presented with hemorrhage, 23 of 26 (88%) had a modified Rankin Scale (mRS) score of 0 to 2 at the last follow-up, and 24 of 26 (92%) obtained radiographic cure. For unruptured BAVMs, all 6 patients with grade I to III BAVM obtained radiographic cure and had an mRS score of 0 to 1 at the last follow-up, whereas 1 of 5 patients (20%) with grade IV and V BAVM had BAVM obliteration and a mean mRS score of 1.8 at the last follow-up. In a total of 93.6 years of follow-up from date of presentation to last clinical follow-up, there was 1 hemorrhage (1.1%/y). Of 30 patients with radiographic obliteration, 2 patients had radiographic recurrence (7% incidence).

CONCLUSION: The majority of ruptured patients had an mRS score of 0 to 2 at the last follow-up and obtained radiographic cure. Unruptured patients with grade I to III BAVMs had superior outcomes compared with those with grade IV and V AVMs. Treatment of grade I to III BAVMs appears safe, and additional study is needed to determine optimal strategies for the management of unruptured grade IV and V BAVMs.

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Clinical experience with navigated 3D ultrasound angiography (power Doppler) in microsurgical treatment of brain arteriovenous malformations

Clinical experience with navigated 3D ultrasound angiography (power Doppler) in microsurgical treatment of brain arteriovenous malformations

Acta Neurochir (2016) 158:875–883

We have previously described a method that has the potential to improve surgery of arteriovenous malformations (AVMs). In the present paper, we present our clinical results.

Materials and methods Of 78 patients referred for AVMs to our University Hospital from our geographical catchment region from 2005 through 2013, 31 patients were operated on with microsurgical technique. 3D MR angiography (MRA) with neuronavigation was used for planning. Navigated 3D ultrasound angiography (USA) was used to identify and clip feeders in the initial phase of the operation. None of our patients was embolized preoperatively as part of the surgical procedure. The niduses were extirpated based on the 3D USA. After extirpation, controls were done with 3D USA to verify that the AVMs were completely removed. The Spetzler three-tier classification of the patients was: A: 21, B: 6, C: 4.

Results Sixty-eight feeders were identified on preoperative MRA and DSA and 67 feeders were identified and clipped by guidance of intraoperative 3D USA. Six feeders identified preoperatively were missed by 3D USA, while five preoperatively unknown feeders were found and clipped. The overall average bleeding was 440 ml. There was a significant reduction in average bleeding in the last 15 operations compared to the first 16 (340 vs. 559 ml, p = 0.019). We had no serious morbidity (GOS 3 or less). New deficits due to surgery were two patients with quadrantanopia (one class B and one class C), the latter (C) also acquired epilepsy. One patient (class A) acquired a hardly noticeable paresis in two fingers. One hundred percent angiographic cure was achieved in all patients, as evaluated by postoperative DSA.

Conclusions Navigated intraoperative 3D USA is a useful tool to identify and clip AVM feeders. Microsurgical extirpation assisted by navigated 3D USA is an effective and safe method for removing AVMs.

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Effect of weekend admission on in-hospital mortality and functional outcomes for patients with acute subarachnoid haemorrhage (SAH)

A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography- Beyond the Fisher Scale

Acta Neurochir (2016) 158:829–835

Aneurysmal subarachnoid haemorrhage (aSAH) is an acute cerebrovascular event with high socioeconomic impact as it tends to affect younger patients. The recent NCEPOD study looking into management of aSAH has recommended that neurovascular units in the United Kingdom should aim to secure cerebral aneurysms within 48 h and that delays because of weekend admissions can increase the mortality and morbidity attributed to aSAH.

Method We used data from a prospective audit of aSAH patients admitted between January 2009 and December 2011. The baseline demographic and clinical features of the weekend and weekday groups were compared using the chisquared test and T-test. Cox proportional hazards models (Proc Phreg in SAS) were used to calculate the adjusted overall hazard of in-hospital death associated with admission on weekend, adjusting for age, sex, baseline WFNS grade, type of treatment received and time from scan to treatment. Sliding dichotomy analysis was used to estimate the difference in outcomes after SAH at 3 months in weekend and weekday admissions.

Results Those admitted on weekends had a significantly higher scan to treatment time (83.05 ± 83.4 h vs 40.4 ± 53.4 h, P < 0.0001) and admission to treatment (71.59 ± 79.8 h vs 27.5 ± 44.3 h, P<0.0001) time. After adjustments for adjusted for relevant covariates weekend admission was statistically significantly associated with excess in-hospital mortality (HR= 2.1, CL [1.13–4.0], P=0.01). After adjustments for all the baseline covariates, the sliding dichotomy analysis did not show effects of weekend admission on long-term outcomes on the good, intermediate and worst prognostic bands.

Conclusions: This study provides important data showing excess in-hospital mortality of patients with SAH on weekend admissions served by the United Kingdom’s National Health Service. However, there were no effects of weekend admission on long-term outcomes.

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Complication-Effectiveness Analysis for Unruptured Intracranial Aneurysm Surgery

Aneurysm surgery

Neurosurgery 78:648–659, 2016

The aim of intervention for unruptured intracranial aneurysms (UIAs) is safe, effective treatment.

OBJECTIVE: To analyze a prospective database for variables influencing the risk of surgery to produce a risk model adjusting this risk for effectively treated aneurysms.

METHODS: First, we identified variables to create a model from multiple logistic regression for complications of surgery leading to a 12-month modified Rankin Scale score .1. Second, we established the long-term cumulative incidence of freedom from retreatment or rupture (treated aneurysm) from Kaplan-Meier analysis. Third, we combined these analyses to establish a model of risk of surgery per effective treatment.

RESULTS: One thousand twelve patients with 1440 UIA underwent 1080 craniotomies. We found that 10.1% (95% confidence interval [CI], 8.4-12.0) of craniotomies resulted in a complication leading to a modified Rankin Scale score .1 at 12 months. Logistic regression found age (odds ratio, 1.04; 95% CI, 1.02-1.06), size (odds ratio, 1.12; 95% CI, 1.09-1.15), and posterior circulation location (odds ratio, 2.95; 95% CI, 1.82-4.78) to be significant. Cumulative 10-year risk of retreatment or rupture was 3.0% (95% CI, 1.3-7.0). The complication-effectiveness model was derived by dividing the complication risk by the 10-year cumulative freedom from retreatment or rupture proportion. Risk per effective treatment ranged from 1% for a 5-mm anterior circulation UIA in a 20-year-old patient to 70% for a giant posterior circulation UIA in a 70-year-old patient.

CONCLUSION: Complication-effectiveness analyses increase the information available with regard to outcome for the management of UIAs.

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Analysis of superiorly projecting anterior communicating artery aneurysms

Analysis of superiorly projecting anterior communicating artery aneurysms

Neurosurg Rev (2016) 39:225–235

Superiorly projecting (SP) anterior communicating artery (AComA) aneurysms are typically described as a homogenous group. Clinically and microsurgically, these aneurysms vary in multiple important characteristics.

We propose a microsurgical classification system for these complex aneurysms and review its implications regarding presentation, microsurgical techniques, and outcome.

This retrospective analysis reviews patients undergoing clipping of SP AComA aneurysms (2005–2013). The classification system is based on the virtual plane created by the A2 segments and its relationship to the aneurysm. Aneurysm type was assessed by intraoperative images and videos. Type 1 is defined by bisection of the dome by the virtual plane. Type 2 is defined by dome projection posterior to this plane. Sagittal rotation of the plane defines type 3. We analyzed clinical presentation, morphology, angiographic characteristics, operative technique, and outcome relative to the classification types.

There were 44 SP AComA aneurysms. 3D angiographic images predicted classification type in 83 %. Type 1 presented more often with SAH (95.5 %, p=0.0046). There was no statistically significant difference between the types regarding patient demographics or aneurysm characteristics. In type 2, fenestrated clips were used frequently (87.5 % p=0.0016), and there was higher rate of intraoperative rupture (37.5 %). Although there was no statistically significant difference between the types in respect to HH grade upon presentation, patients with type 2 aneurysms experienced higher rates of poor GOS (50 %).

The proposed classification system for SP AComA aneurysms has implications regarding surgical planning, micro-dissection, clipping, and outcome. Type 2 aneurysms carry significant surgical risk.

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Recurrence of Cerebral Arteriovenous Malformations Following Resection in Adults: Does Preoperative Embolization Increase the Risk?

Recurrence of Cerebral Arteriovenous Malformations Following Resection in Adults- Does Preoperative Embolization Increase the Risk?

Neurosurgery 78:562–571, 2016

Complete surgical resection of arteriovenous malformations (AVMs), documented by postoperative angiography, is generally felt to represent cure, obviating the need for long-term follow-up imaging. Although AVM recurrence has been reported in the pediatric population, this phenomenon has only rarely been documented in adults. Recurrence after treatment solely with embolization, however, has been reported more frequently. Thus, patients undergoing multimodal therapy with surgery following preoperative embolization may also be at higher risk for recurrence.

OBJECTIVE: To determine if preoperative embolization contributes to recurrences of AVMs after complete surgical resection.

METHODS: A retrospective study of patients undergoing AVM resection was performed. Those with complete surgical AVM resection, confirmed by negative early postoperative cerebral angiography and with available follow-up angiographic imaging .6 months postoperatively were included.

RESULTS: Two hundred three patients underwent AVM resection between 1995 and 2012. Seventy-two patients met eligibility criteria. There were 3 recurrences (4%). Deep venous drainage and diffuse type of AVM nidus were significantly associated with recurrence. Although preoperative embolization did not reach statistical significance as an independent risk factor, radiographic data supported its role in every case, with the site of recurrence correlating with deep regions of nidus previously obliterated by embolization.

CONCLUSION: AVM recurrences in the adult population may have a multifactorial origin. Although deep venous drainage and diffuse nidus are clearly risk factors, preoperative embolization may also be a contributing factor with the potential for recurrence of unresected but embolized portions of the AVM. Follow-up angiography at 1 to 3 years appears to be warranted.

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Association of Hemodynamic Factors With Intracranial Aneurysm Formation and Rupture

Association of Hemodynamic Factors With Intracranial Aneurysm Formation and Rupture

Neurosurgery 78:510–520, 2016

Recent evidence suggests a link between the magnitude and distribution of hemodynamic factors and the formation and rupture of intracranial aneurysms. However, there are many conflicting results.

OBJECTIVE: To quantify the effect of hemodynamic factors on aneurysm formation and their association with ruptured aneurysms.

METHODS: We performed a systematic review and meta-analysis through October 2014. Analysis of the effects of hemodynamic factors on aneurysm formation was performed by pooling the results of studies that compared geometrical models of intracranial aneurysms and “preaneurysm” models where the aneurysm was artificially removed. Furthermore, we calculated pooled standardized mean differences between ruptured and unruptured aneurysms to quantify the association of hemodynamic factors with ruptured aneurysms. Standard PRISMA guidelines were followed.

RESULTS: The hemodynamic factors that showed high positive correlations with location of aneurysm formation were high wall shear stress (WSS) and high gradient oscillatory number, with pooled proportions of 78.8% and 85.7%, respectively. Positive correlations were largely seen in bifurcation aneurysms, whereas negative correlations were seen in sidewall aneurysms. Mean and normalized WSS were significantly lower and low shear area significantly higher in ruptured aneurysms.

CONCLUSION: Pooled analyses of computational fluid dynamics models suggest that an increase in WSS and gradient oscillatory number may contribute to aneurysm formation, whereas low WSS is associated with ruptured aneurysms. The location of the aneurysm at the bifurcation or sidewall may influence the correlation of these hemodynamic factors.

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Ideal clipping methods for unruptured middle cerebral artery bifurcation aneurysms based on aneurysmal neck classification

MCAb aneurysms clipping

Neurosurg Rev (2016) 39:215–224

Endovascular coiling is widely used for many cerebral aneurysms; however, in cases of middle cerebral artery bifurcation (MCBIF) aneurysms, it is associated with a higher incidence of unfavorable outcomes compared to microsurgical clippings. In this retrospective study, we aimed to investigate the outcomes of microsurgical clipping for unruptured MCBIF aneurysms and determine the ideal clipping methods for different aneurysm subtypes.

From January 2011 to December 2013, 203 aneurysms with saccular shape (<25 mm) were treated by an experienced neurosurgeon. Depending on the involvement of the aneurysmal thin wall, the aneurysm neck was classified as follows: subtype I, limited bifurcation; subtype II, progressed to M1 trunk; subtype III, progressed to M2 trunk; subtype IV, progressed to M1 and one M2 trunk; and subtype V, progressed to M1 and two M2 trunks. The clipping methods included simple, sliding, interlocking, or mixed approaches.

Aneurysm clippings were accomplished without any morbidity in all cases, and seven cases had a minimal neck remnant. The following clipping methods were predominantly used: subtype I, simple (90.2 %) and sliding (8.8 %) (mean = 1.2 clips); subtype II, interlocking (51.4 %), sliding (30.0 %), mixed (15.7 %), and simple (2.9 %) (2.4 clips); subtype III, simple (57.5 %) and sliding (42.5 %) (1.5 clips); subtype IV, interlocking (64.3 %) (2.1 clips), simple (10.7 %), sliding (14.3 %), and mixed (10.7 %); and subtype V, interlocking (50.0 %), sliding (35.7 %), and mixed (14.3 %) methods with multiple clips (2.8 clips).

If an appropriate clipping method is selected according to the neck classification, satisfactory surgical obliteration can be achieved for unruptured MCBIF aneurysms without morbidity.

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Stereotactic Radiosurgery for Arteriovenous Malformations: The Effect of Treatment Period on Patient Outcomes

AVM

Neurosurgery 78:499–509, 2016

Stereotactic radiosurgery (SRS) has been performed on patients with cerebral arteriovenous malformations (AVMs) for over 40 years.

OBJECTIVE: To evaluate the impact of treatment period on obliteration, intracranial hemorrhage (ICH), and radiation-induced complications (RICs).

METHODS: Retrospective comparison of 381 AVM patients having SRS during a 20-year period (group 1, January 1990 through March 1997, n = 160; group 2, April 1997 through December 2009, n = 221). The median radiological and clinical follow-up after initial SRS was 77 months and 93 months, respectively.

RESULTS: Obliteration was 59.1% at 4 years and 85.1% at 8 years. Obliteration was more common in patients with hemispheric or cerebellar AVMs (P = .001), smaller prescription isodose volume (PIV) (P < .001), and group 1 patients (P < .001). The ICH rate was 7.7% at 4 years and 10.6% at 8 years. ICH was more common in older patients (P = .02), patients with deep AVM (P = .01), and larger PIV (P < .001). There was no difference in the ICH rate between the treatment groups (P = .18). The rate of permanent RICs was 4.4% at 4 years and 8.6% at 8 years. RICs were more common with larger PIVs (P < .001) and group 1 patients (P = .02). There was no difference in the number of patients having obliteration without new deficits between the 2 treatment periods (68.8% vs 73.3%, P = .33).

CONCLUSION: Advances in SRS procedures over the past 20 years have resulted in a lower risk of RIC, but fewer patients had AVM obliteration. Increasing the prescription dose for patients with medium- and large-volume AVMs by using current conformal dose-planning techniques may improve the obliteration rate while maintaining a low risk of RICs.

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Comparison of Outcome Between Surgical and Conservative Management of Symptomatic Spinal Cord Cavernous Malformations

Comparison of Outcome Between Surgical and Conservative Management of Symptomatic Spinal Cord Cavernous Malformations

Neurosurgery 78:552–561, 2016

Intramedullary cavernous malformations (CMs) are rare lesions with unclear natural history.

OBJECTIVE: To compare the functional outcomes of spinal CMs managed surgically and conservatively.

METHODS: We performed a retrospective study of patients diagnosed with intramedullary CMs seen at our institution from 2006 to 2013. Functional outcomes of patients were assessed by treatment modality with the Modified McCormick Scale and Karnofsky Performance Status.

RESULTS: We identified a total of 85 study-eligible patients; 51 (60.0%) were male. Mean age of patients was 40.5 years. Fifty-eight patients underwent microsurgical removal, and 27 patients underwent conservative management. All patients except 1 harbored a single symptomatic intramedullary CM. Mean follow-up time was 42.8 months. For the surgical group (n = 58), 51 CMs were completely resected. During the follow-up period, 40 patients (69.0%) within the surgical group had improvement in neurological state, 16 patients (27.6%) remained unchanged, and 2 patients (3.4%) experienced deteriorated functional status. In the conservative group, 4 patients (14.8%) had improvement of their symptoms, 19 patients (70.4%) remained in baseline, and 4 patients (14.8%) deteriorated. No significant statistical difference was observed in followup Karnofsky Performance Status assessment (odds ratio = 0.89; 95% confidence interval = 0.73-1.08; P = .15) or Modified McCormick Scale assessment (odds ratio = 0.90; 95% confidence interval = 0.74-1.10; P = .30) after adjustment for preoperative lesion size and location. Annual hemorrhagic risk was 3.9% in conservatively managed patients. In contrast, no patients experienced subsequent hemorrhages after surgical resection.

CONCLUSION: Surgical resection of intramedullary CMs eliminates the risk of subsequent hemorrhagic and may achieve satisfactory outcome when patients are carefully selected. Although conservative management is recommended in patients at high surgical risk, they should be closely monitored because of persistent hemorrhagic risk.

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Microembolism after endovascular coiling of unruptured cerebral aneurysms: incidence and risk factors

Microembolism after endovascular coiling of unruptured cerebral aneurysms

J Neurosurg 124:777–783, 2016

The incidence and risk factors of microembolic lesions on MR diffusion-weighted imaging (DWI) were analyzed after the endovascular coiling of unruptured intracranial aneurysms (UIAs).

Methods Data obtained from 271 consecutive patients (70 men and 201 women; median age 57 years; range 23–79 years) who presented with UIA for coil embolization between July 2011 and June 2013 were analyzed. Two independent reviewers examined the DWI and apparent diffusion coefficient maps obtained the following day for the presence of restrictive diffusion spots and counted the number of spots. Multivariate analysis was then performed to identify independent risk factors for developing microembolism following the coiling of an aneurysm.

Results Microembolic lesions were noted in 101 of 271 patients (37.3%). The results of the multivariate analysis showed that the following factors significantly influenced the risk for microembolism: age, diabetes, previous history of ischemic stroke, high-signal FLAIR lesions in the white matter, multiple aneurysms, and the insertion of an Enterprise stent (all ORs > 1.0 and all p values < 0.05). Previously known risk factors such as prolonged procedure duration, aneurysm size, and decreased antiplatelet function did not show any significant influence.

Conclusions The incidence of microembolism after endovascular coiling of UIA was not low. Lesions occurred more frequently in patients with vascular status associated with old age, diabetes, and previous stroke. Aneurysm multiplicity and the type of stent used for treatment also influenced lesion occurrence.

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Height of aneurysm neck and estimated extent of brain retraction: powerful predictors of olfactory dysfunction after surgery for unruptured anterior communicating artery aneurysms

Height of aneurysm neck and estimated extent of brain retraction- powerful predictors of olfactory dysfunction after surgery for unruptured anterior communicating artery aneurysms

J Neurosurg 124:720–725, 2016

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

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

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

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

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Long-term outcomes after surgical and endovascular treatment of spinal dural arteriovenous fistulae

SDAVF

Eur Spine J (2016) 25:748–754

To examine the validity of our treatment strategy for spinal dural arteriovenous fistulae (SDAVF), based on the treatment results and the long-term outcome.

Methods This study included 50 SDAVF patients (38 men, 12 women, mean age 63.2 years) with progressive myelopathy. The treatment strategy involved embolization as the initial management tool and surgery if embolization was considered unsuitable. Their medical records were evaluated to identify the treatment results and functional outcomes. The mean follow-up period was 81.2 months (range 27–184 months).

Results Complete obliteration was achieved in 22 (71.0 %) of 31 embolized patients and in 18 of 19 (94.7 %) operated patients. The initial success rate was significantly lower in embolized than operated patients. At the last follow-up, 33 of the 50 patients (66 %) manifested im- proved gait and 16 (32 %) improved micturition. The ac- tivity of daily living (ADL) was improved in 33 (66 %). When we compared the rates of functional improvement at the last follow-up, there was no significant difference be- tween patients treated initially by embolization or surgery.

Conclusions The long-term outcomes in SDAVF patients treated by multidisciplinary management with first-line embolization were comparable to those in earlier surgical series. However, our results were unable to demonstrate the superiority of endovascular embolization to surgical treatment for SDAVF. For the purpose of justifying endovascular embolization as a first-line treatment for SDAVF, it will be necessary to show further improvement in both the initial treatment success and the complication rates.

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