Category: Vascular

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Flexible Omnidirectional Carbon Dioxide Laser as an Effective Tool for Resection of Brainstem, Supratentorial, and Intramedullary Cavernous Malformations

Ponto-mesencephalic cavernoma

Operative Neurosurgery 10:34–45, 2014

Lasers have a long history in neurosurgery, yet bulky designs and difficult ergonomics limit their use. With its ease of manipulation and multiple applications, the OmniGuide CO2 laser has reintroduced laser technology to the microsurgical resection of brain and spine lesions. This laser, delivered through a hollow-core fiber lined with a unidirectional mirror, minimizes energy loss and allows precise targeting.

OBJECTIVE: To analyze resections performed by the senior author from April 2009 to March 2013 of 58 cavernous malformations (CMs) in the brain and spine with the use of the OmniGuide CO2 laser, to reflect on lessons learned from laser use in eloquent areas, and to share data on comparisons of laser power calibration and histopathology.

METHODS: Data were collected from electronic medical records, radiology reports, operative room records, OmniGuide CO2 laser case logs, and pathology records.

RESULTS: Of 58 CMs, approximately 50% were in the brainstem (30) and the rest were in supratentorial (26) and intramedullary spinal locations (2). Fifty-seven, ranging from 5 to 45 mm, were resected, with a subtotal resection in 1. Laser power ranged from 2 to 10 W. Pathology specimens showed minimal thermal damage compared with traditionally resected specimens with bipolar coagulation.

CONCLUSION: The OmniGuide CO2 laser is safe and has excellent precision for the resection of supratentorial, brainstem, and spinal intramedullary CMs. No laser-associated complications occurred, and very low energy was used to dissect malformations from their surrounding hemosiderin-stained parenchymas. The authors recommend its use for deep-seated and critically located CMs, along with traditional tools.

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Minimally invasive microsurgery for anterior circulation aneurysms

MIS for Anterior Circulation Aneurysms

Acta Neurochir (2014) 156:493–503

The aim of our study was to evaluate minimally invasive techniques for the treatment of anterior circulation aneurysms versus standard surgery, and to calculate the impact of these techniques on health resources, length of stay, and treatment costs.

Methods A consecutive series of 24 patients with ruptured and 30 with unruptured anterior circulation aneurysms treated with minimally invasive microsurgery (MIM) by the same surgeon was compared with a matched series of standard microsurgeries (SM) conducted for 23 ruptured and 22 unruptured aneurysms. Complication rates, aneurysm obliteration, modified Rankin Scale (mRS) outcomes, length of stay, and treatment costs were assessed.

Results Surgical complications, aneurysm obliteration rates and mRS outcomes were comparable between MIM and SM groups in ruptured and unruptured aneurysm cohorts. MIM resulted in shorter operative times both in unruptured (102.7±4.35 vs 194.7±10.26 min, p<0.0001) and ruptured aneurysms (124.3±827 vs 209±13.84 min, p<0.0001). Length of stay was reduced in patients with MIM for unruptured aneurysms (1.55±24 vs 4.28±0.71 days, p<0.000,1) but not in those with ruptured aneurysms. MIM reduced treatment costs of unruptured aneurysm patients, mainly through reduced utilization of inpatient resources (non-acute bed costs in CAD: 371.2±80.99 vs 1440±224.1, p<0.0001), whereas costs were comparable in patients with ruptured aneurysms.

Conclusion Minimally invasive surgery is a safe and effective approach for the treatment of ruptured and unruptured aneurysms of the anterior circulation. In patients with unruptured aneurysms, reduced invasiveness and shorter operative times decreased length of stay, which reflects improved patient postoperative recovery. Overall, this translated into bed resource economy and cost reduction.

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Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Classification Scheme for Planning Optimal Surgical Strategies

Middle Cerebral Artery Bifurcation Aneurysms- An Anatomic Classification Scheme for Planning Optimal Surgical Strategies

Operative Neurosurgery 10:145–155, 2014

Changing landscapes in neurosurgical training and increasing use of endovascular therapy have led to decreasing exposure in open cerebrovascular neurosurgery. To ensure the effective transition of medical students into competent practitioners, new training paradigms must be developed.

OBJECTIVE: Using principles of pattern recognition, we created a classification scheme for middle cerebral artery (MCA) bifurcation aneurysms that allows their categorization into a small number of shape pattern groups.

METHODS: Angiographic data from patients with MCA aneurysms between 1995 and 2012 were used to construct 3-dimensional models. Models were then analyzed and compared objectively by assessing the relationship between the aneurysm sac, parent vessel, and branch vessels. Aneurysms were then grouped on the basis of the similarity of their shape patterns in such a way that the in-class similarities were maximized while the total number of categories was minimized. For each category, a proposed clip strategy was developed.

RESULTS: From the analysis of 61 MCA bifurcation aneurysms, 4 shape pattern categories were created that allowed the classification of 56 aneurysms (91.8%). The number of aneurysms allotted to each shape cluster was 10 (16.4%) in category 1, 24 (39.3%) in category 2, 7 (11.5%) in category 3, and 15 (24.6%) in category 4.

CONCLUSION: This study demonstrates that through the use of anatomic visual cues, MCA bifurcation aneurysms can be grouped into a small number of shape patterns with an associated clip solution. Implementing these principles within current neurosurgery training paradigms can provide a tool that allows more efficient transition from novice to cerebrovascular expert.

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Extended Subtemporal Transtentorial Approach to the Anterior Incisural Space and Upper Clival Region: Experience With Posterior Circulation Aneurysms

Extended Subtemporal Transtentorial Approach to the Anterior Incisural Space and Upper Clival Region- Experience With Posterior Circulation Aneurysms

Neurosurgery 10:15–24, 2014

Although most posterior circulation aneurysms are currently treated by endovascular means, some are not amenable to this treatment modality. The narrow working window afforded by the anterolateral and lateral surgical approaches often translates into suboptimal visualization and limited maneuverability.

OBJECTIVE: We present a modified technique of tentorial incision and reflection that optimizes the exposure achieved with the traditional subtemporal approach and report our clinical experience in a series of posterior circulation aneurysms.

METHODS: Retrospective review of patients operated via an extended subtemporal transtentorial approach for posterior circulation aneurysms. The modified tentorial incision implies dissection of the trochlear nerve along its dural canal up to its entrance into the cavernous sinus and incision of a tentorial flap that extends up to Meckel cave, which is then reflected far anterolaterally. Clinical and radiological data were reviewed.

RESULTS: This series comprises 18 patients (21 procedures). Ten patients presented (56%) with a subarachnoid hemorrhage. Aneurysms most frequently arose from the basilar tip (61%) and were of small size (50%) and saccular morphology (72%). Two patients underwent surgery following unsuccessful endovascular treatment. Aneurysm treatment was successful on the first attempt in 90% (19/21) and after a second attempt in 10% (2/21). Documented postoperative palsies of the oculomotor (n = 3) and trochlear (n = 1) nerves were all transient. No procedure-related mortality occurred.

CONCLUSION: This modified technique of tentorial incision and reflection optimizes visibility, anatomic orientation, and maneuverability by increasing the rostrocaudal and anterolateral exposure obtained via the extended subtemporal transtentorial route without permanent postoperative trochlear nerve deficit.

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Stereotactic radiosurgery for arteriovenous malformations of the cerebellum

Bowden et al

J Neurosurg 120:583–590, 2014

Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery.

Methods. This single-institution retrospective analysis reviewed the authors’ experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy).

Results. Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%).

Conclusions. Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.

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Analysis of the relationship between different bleeding positions on intraoperative rupture anterior circulation aneurysm and surgical treatment outcome

Intraoperative rupture anterior circulation aneurrysms

Acta Neurochir (2014) 156:481–491

It is well recognized that intraoperative aneurysm rupture (IAR) is a serious event that is difficult to manage and has a relatively serious influence on a patient’s prognosis. The aim of this study was to evaluate the prognostic value of different bleeding positions of IAR in patients, and to describe the technique that the authors have used to clip the ruptured aneurysms.

Methods From May 2009 to March 2012, a total of 148 aneurysms in 135 consecutive patients in our institution underwent clipping surgeries, and 31 IARs occurred in 30 patients. The clinical data of all patients were retrospectively analyzed. Statistics analysis was performed to analyze possible factors of different bleeding positions of IARs, to assist observation.

Results Outcome was estimated by Glasgow outcome scale via following up or calling back within 1, 3, and 6 months after surgery: 94 patients were 5’, 23 patients were 4’, nine patients were 3’, two patients were 2’ and eight patients were 1’. There was no significant difference between the outcome of IAR and that of no intraoperative aneurysm rupture (NIAR) in Hunt–Hess groups 0–III (P =0.802) and Hunt–Hess groups IV–V (P =0.229), and the different bleeding positions were shown to be an important factor that significantly influences the patients’ prognosis (P=0.001).

Conclusions Different bleeding positions of IAR have a significant impact on surgical outcome; IAR of the neck is the most devastating complication. If surgeons take appropriate measures according to different bleeding positions, the efficiency, accuracy and security of the operation will be improved

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A prospective study of microscope-integrated intraoperative fluorescein videoangiography during arteriovenous malformation surgery

intraoperative fluorescein videoangiography during arteriovenous malformation surgery

Neurosurg Focus 36 (2):E15, 2014

The authors report on the use of a recently developed microscope-integrated fluorescent module using low-dose intravenous fluorescein for videoangiography during arteriovenous malformation (AVM) surgery.

Methods. The authors analyzed the application of a low-dose intraoperative fluorescein in 4 consecutive patients undergoing AVM surgery. The ability to distinguish the associated vessels of the AVM from normal vessels and to assess the degree of AVM obliteration based on videoangiography of venous drainage was specifically analyzed.

Results. All 4 patients underwent fluorescein angiography without complication. In each case, videoangiography confirmed recognition of feeding arteries and draining veins through the operating oculars under the fluorescent mode. In one case involving a large frontal AVM, videoangiography demonstrated mainly cortical veins on the surface of the AVM and alerted the senior author to first tackle the feeding arteries in the interhemispheric space. While evaluating the flow within the different draining veins after most of the AVM was disconnected, videoangiography also prioritized the order for disconnection of large draining veins to allow mobilization the AVM and exposure of the remaining deep arterial feeders. In the other 3 cases, videoangiography allowed easy recognition of the angioarchitecture of the AVMs, estimated its cortical boundaries, and most importantly, assessed the flow within the draining veins before their disconnection.

Conclusions. The authors found fluorescein videoangiography to be a useful adjunct in resection of AVMs. This technology offers the unique ability to visualize fluorescent vessels and nonfluorescent tissues in near-natural colors simultaneously and permits microsurgical manipulation of relevant structures under the fluorescent mode. Largerscale studies are needed to establish its efficacy and wider applicability.

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Essentials in intraoperative indocyanine green videoangiography assessment for intracranial aneurysm surgery

ICG aneurysm

Neurosurg Focus 36 (2):E7, 2014

Indocyanine green (ICG) videoangiography (VA) in cerebral aneurysm surgery allows confirmation of blood flow in parent, branching, and perforating vessels as well as assessment of remnant aneurysm parts after clip application. A retrospective analysis and review of the literature were conducted to determine the current essential advantages of ICG-VA in aneurysm surgery.

Methods. The authors retrospectively evaluated all aneurysm cases treated with the aid of intraoperative ICG-VA at a single institution between 2007 and 2013. They also analyzed the literature published since the initial description of ICG-VA in 2003.

Results. Two hundred forty-six procedures were performed in 232 patients harboring 295 aneurysms. The pa- tients, whose mean age was 54 years, consisted of 159 women and 73 men. One hundred twenty-four surgeries were performed after subarachnoid hemorrhage, and 122 were performed for incidental aneurysms. Single aneurysms were clipped in 185 patients, and multiple aneurysms were clipped in 47 (mean aneurysm diameter 6.9 mm, range 2–40 mm). No complications associated with ICG-VA occurred. Intraoperative microvascular Doppler ultrasonography was performed before ICG-VA in all patients, and postoperative digital subtraction angiography (DSA) studies were available in 121 patients (52.2%) for retrospective comparative analysis. In 22 (9%) of 246 procedures, the clip posi- tion was modified intraoperatively as a consequence of ICG-VA. Stenosis of the parent vessels (16 procedures) or occlusion of the perforators (6 procedures), not detected by micro-Doppler ultrasonography, were the most common problems demonstrated on ICG-VA. In another 11 procedures (4.5%), residual perfusion of the aneurysm was ob- served and one or more additional clips were applied. Vessel stenosis or a compromised perforating artery occurred independent of aneurysm location and was about equally common in middle cerebral artery and anterior communi- cating artery aneurysms. In 2 procedures (0.8%), aneurysm puncture revealed residual blood flow within the lesion, which had not been detected by the ICG-VA. In the postoperative DSA studies, unexpected small (< 2 mm) aneurysm neck remnants, which had not been detected on intraoperative ICG-VA, were found in 11 (9.1%) of 121 patients. However, these remnants remained without consequence except in 1 patient with a 6-mm residual aneurysm dome, which was subsequently embolized with coils.

Conclusions. In a large cohort of consecutive patients, ICG-VA proved to be a helpful intraoperative tool and led to a significant intraoperative clip modification rate of 15%. However, small, < 2-mm-wide neck remnants and a 6-mm residual aneurysm were missed by intraoperative ICG-VA in up to 10% of patients. Results in this study confirm that DSA is indispensable for postoperative quality assessment in complex aneurysm surgery.

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Intraoperative rerupture during surgical treatment of aneurysmal subarachnoid hemorrhage is not associated with an increased risk of vasospasm

aneurysm

J Neurosurg 120:409–414, 2014

Intraoperative rerupture during open surgical clipping of cerebral aneurysms in subarachnoid hemorrhage (SAH)is a relatively frequent and potentially catastrophic occurrence. Patients who suffer rerupture have been shown to have worse outcomes at discharge compared with those who do not have rerupture. Perioperative injury likely plays a large part in the clinical worsening of these patients. However, due to the increased vessel manipulation and repeat exposure to acute hemorrhage, it is possible that secondary injury from increased incidence of vasospasm also contributes. Identifying an increased rate of vasospasm in these patients would justify early aggressive treatment with measures to prevent delayed cerebral ischemia. The authors investigated whether patients who suffer intraoperative rerupture during surgical treatment of ruptured cerebral aneurysms are at increased risk of developing vasospasm.

Methods. Five hundred consecutive patients treated with open surgical clipping for SAH were reviewed, and clinical and imaging data were collected. Angiographic vasospasm was defined as vessel narrowing believed to be consistent with vasospasm on angiography. Symptomatic vasospasm was defined as angiographic vasospasm in the setting of a clinical change attributable to vasospasm. Rates of angiographic and symptomatic vasospasm among patients with and without intraoperative rerupture were compared.

Results. There were no significant differences between the groups with and without rupture with respect to age, sex, modified Fisher grade, history of hypertension, or smoking. The group with intraoperative rupture had more patients with Hunt and Hess Grade I. Angiographic vasospasm was noted in 279 (66%) of the 425 patients without rerupture compared with 49 (65%) of the 75 patients with rerupture (p = 1.0, Fisher’s exact test). Symptomatic vasospasm was noted in 154 (36%) of the 425 patients without rerupture, compared with 31 (41%) of the 75 patients with rerupture (p = 0.44, Fisher’s exact test). In multivariate analysis, higher modified Fisher grade was significantly predictive of vasospasm, whereas older age and male sex were protective.

Conclusions. This study found no significant influence of intraoperative rerupture during open surgical clipping on the rate of angiographic or symptomatic vasospasm. Brief exposure to acute hemorrhage and vessel manipulation associated with rerupture events did not affect the rate of vasospasm. Risk of vasospasm was related to increased modified Fisher grade, and inversely related to age and male sex. These results do not justify early, targeted vasospasm therapy in patients with intraoperative rerupture.

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Spontaneous Intracerebral and Intraventricular Hemorrhage: Advances in Minimally Invasive Surgery and Thrombolytic Evacuation, and Lessons Learned in Recent Trials

Spontaneous_Intracerebral_and_Intraventricular

Neurosurgery 74:S142–S150, 2014

Optimal management of spontaneous intracerebral hemorrhage (ICH) remains one of the highly debated areas in the field of neurosurgery. Earlier studies comparing open surgical intervention with best medical management failed to show a clear benefit.

More recent experience with minimally invasive techniques has shown greater promise. Well-designed phase II trials have confirmed the safety and preliminary treatment effect of thrombolytic aspiration and clearance of spontaneous ICH and associated intraventricular obstructive hemorrhage.

Those trials are reviewed, including respective protocols and technical nuances, and lessons learned regarding patient selection, the concept of hemorrhage stabilization, optimization of the surgical procedure, and thrombolytic dosing decisions.

These concepts have been incorporated in the design of ongoing definite phase III randomized trials (MISTIE and CLEAR) funded by the National Institutes of Health. These are presented including the role of surgical leadership in the training and monitoring of the surgical task and quality assurance. The impact of these techniques on neurosurgical practice is discussed.

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Cerebral Microbleeds in Patients With Acute Subarachnoid Hemorrhage

Cerebral Microbleeds in Patients With Acute Subarachnoid Hemorrhage

Neurosurgery 74:176–181, 2014

Cerebral microbleeds (CMBs) are commonly found after stroke but have not previously been studied in patients with subarachnoid hemorrhage (SAH). OBJECTIVE: To study the prevalence, radiographic patterns, predictors, and impact on outcome of CMBs in patients with SAH.

METHODS: We analyzed retrospectively 39 consecutive patients who underwent T2*- weighted gradient-echo imaging within 7 days after onset of spontaneous SAH. We report the frequency and location of CMBs and show their association with demographics, vascular risk factors, the Hunt-Hess grade, the modified Fisher Scale, the Acute Physiological and Chronic Health Evaluation II, magnetic resonance imaging findings including diffusion-weighted imaging lesions, and laboratory data, as well as data on rebleeding, global cerebral edema, delayed cerebral ischemia, seizures, the Telephone Interview for Cognitive Status, and the modified Rankin Scale.

RESULTS: Eighteen patients (46%) had CMBs. Of these patients, 9 had multiple CMBs, and overall a total of 50 CMBs were identified. The most common locations of CMBs were lobar (n = 23), followed by deep (n = 15) and infratentorial (n = 12). After adjustment for age and history of hypertension, CMBs were related to the presence of diffusion-weighted imaging lesions (odds ratio, 5.24; 95% confidence interval, 1.14-24.00; P = .03). Three months after SAH, patients with CMBs had nonsignificantly higher modified Rankin Scale scores (odds ratio, 2.50; 95% confidence interval, 0.67-9.39; P = .18).

CONCLUSION: This study suggests that CMBs are commonly observed and associated with diffusion-weighted imaging lesions in patients with SAH. Our findings may represent a new mechanism of tissue injury in SAH. Further studies are needed to investigate the clinical implications of CMBs.

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Bypass surgery for complex middle cerebral artery aneurysms

By-pass surgery in MCAA

J Neurosurg 120:398–408, 2014

The object of this study was to describe the authors’ institutional experience in the treatment of complex middle cerebral artery (MCA) aneurysms necessitating bypass and vessel sacrifice.

Methods. Cases in which patients with MCA aneurysms were treated with a combination of bypass and parent artery sacrifice were reviewed retrospectively.

Results. The authors identified 24 patients (mean age 46 years) who were treated with bypass and parent artery sacrifice. The aneurysms were located in the M1 segment in 7 patients, MCA bifurcation in 8, and more distally in 9. The mean aneurysm diameter was 30 mm (range 7–60 mm, median 26 mm). There were 8 saccular and 16 fusiform aneurysms. Twenty-one extracranial-intracranial and 4 intracranial-intracranial bypasses were performed. Partial or total trapping (only) of the parent artery was performed in 17 cases, trapping with resection of aneurysm in 3, and aneurysm clipping with sacrifice of an M2 branch in 4. The mean follow-up period was 27 months. The aneurysm obliteration rate was 100%. No recanalization of the aneurysms was detected during follow-up. There was 1 perioperative death (4% mortality rate) and 6 cerebrovascular accidents, causing permanent morbidity in 5 patients. The median modified Rankin Scale score of patients with an M1 aneurysm increased from 0 preoperatively to 2 at latest follow-up, while the score was unchanged in other patients. Most of the permanent deficits were associated with M1 aneurysms. Twenty-one patients (88%) had good outcome as defined by a Glasgow Outcome Scale score of 4 or 5.

Conclusions. Bypass in combination with parent vessel occlusion is a useful technique with acceptable frequencies of morbidity and mortality for complex MCA aneurysms when conventional surgical or endovascular techniques are not feasible. The location of the aneurysm should be considered when planning the type of bypass and the site of vessel occlusion. Flow alteration by partial trapping may be preferable to total trapping for the M1 aneurysms.

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Combined endovascular and surgical treatment of fusiform aneurysms of the basilar artery

Combined endovascular and surgical treatment of fusiform aneurysms of the basilar artery- technical note

Acta Neurochir (2014) 156:53–61

To present the combined treatment of fusiform basilar artery aneurysms consisting of a surgical posterior fossa decompressive craniectomy and ventriculoperitoneal (VP) shunt operation at the same sitting, before the endovascular procedure with telescopic stenting of the aneurysmatic vessel segment in four cases.

Methods Combined treatment involving surgical procedure consisting of ventriculoperitoneal shunt placement for hydrocephalus and an occipital bone craniectomy and C1 vertebrae posterior laminectomy to decompress the posterior fossa in the same session. After surgery, the patients were loaded with acetylsalicylic acid and clopidogrel, and then the endovascular treatment was performed.

Results All of the procedures were performed successfully without technical difficulty. The patients tolerated the procedures well and all cases showed remodelling with the overlapping stent technique. The patients were discharged home with baseline neurological situation and computed tomography (CT) angiography was performed at the 3rd month.

Conclusion This technique is a safer endovascular approach to treating symptomatic fusiform basilar artery aneurysms by protecting patients from both the haemorrhagic complications of anticoagulant therapy and thrombotic complications due to the interruption of anticoagulant therapy, while treating the hydrocephalus and compression by surgical means.

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Cognard Type V Intracranial Dural Arteriovenous Shunt

Cognard Type V Intracranial Dural Arteriovenous Shunt

Neurosurgery 74:E135–E142, 2014

Prompt diagnosis of intracranial dural arteriovenous shunt (DAVS) with spinal venous drainage, classified as Cognard type V, is difficult. We investigated the angiographic and magnetic resonance imaging (MRI) characteristics of Cognard type V DAVS to determine the reason for the difficulty in early diagnosis.

CLINICAL PRESENTATION: We systematically reviewed 54 published and 3 new cases of Cognard type V DAVS. The pattern of venous drainage was classified on the basis of relative dominance of the anterior and posterior spinal veins with the use of angiograms. T2-weighted sagittal MRIs were used to detect signal flow voids of enlarged spinal veins. Types of venous drainage were determined in 49 of the 57 cases. Twentyeight and 8 cases showed a dominance of anterior and posterior spinal venous drainage, respectively. In 13 cases, venous drainage was equally distributed through the anterior and posterior spinal veins. Of 41 cases with an abnormally dilated anterior spinal vein, MRIs were available for 25 cases. Signal flow voids of enlarged anterior spinal veins were detected in 9 cases (36.0%), whereas dilatation of the posterior spinal veins was apparent in 9 of 16 cases (56.3%). Overall, MRI detected enlargement of either anterior or posterior spinal veins in 15 of 41 cases (36.6%).

CONCLUSION: In Cognard type V DAVS, anterior venous drainage is dominant. Because the anterior spinal veins are located subpially, flow voids are less prominent on sagittal T2-weighted MRI. This may lead to difficulties in diagnosing. Evaluation with MR angiography may compensate for these limitations.

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Anatomy and morphology of giant aneurysms

Giant aneurysms

Acta Neurochir (2014) 156:1–10

Giant intracranial aneurysms are rare and heterogeneous lesions with complex vascular anatomy. The aim of this retrospective study was to provide a comprehensive description of the anatomical features of giant aneurysms.

Methods We identified 125 patients with 129 giant aneurysms (≥25 mm) who were treated between 1987 and 2007 at the Department of Neurosurgery of Helsinki University Central Hospital (HUCH). All the imaging studies and medical records were reviewed for relevant information.

Results The distribution of the giant aneurysms among regions was as follows: internal carotid artery (ICA) 39 %, middle cerebral artery (MCA) 32 %, vertebrobasilar and posterior cerebral artery (VB-PCA) region 25 %, and anterior cerebral artery (ACA) including the anterior communicating artery 5%. The cavernous ICA segment (n =21, 16 %) and the MCA bifurcation (n =25, 19 %) were the most frequent specific locations. Half (n =11) of all fusiform aneurysms were found in the VB-PCA region. As many as 41 % of the giant MCA aneurysms were ruptured. Major anatomic variations were found in three (2 %) and multiple giant aneurysms in three (2 %) patients.Wall calcification was noted in 24 % and intraluminal thrombosis in 33 % of ruptured giant aneurysms (n =42).

Conclusions The majority of giant aneurysms are located in the ICA and MCA regions, while the ACA region is an exceptional site. The MCA region is the most common site for ruptured giant aneurysms. Associated anatomic variations and the multiplicity of giant aneurysms are a rare finding.

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Anatomical variants of the basal vein of Rosenthal: prevalence in idiopathic subarachnoid hemorrhage

Anatomical variants of the basal vein of Rosenthal- prevalence in idiopathic subarachnoid hemorrhage

Acta Neurochir (2014) 156:45–51

Spontaneous, non traumatic subarachnoid hemorrhage (SAH) is a significant clinical problem that occurs most commonly as a result of aneurysm rupture. In approximately 15 % of cases, nor aneurysm or other vascular malformation can be identified by cerebral angiography as origin of the hemorrhage, and these are commonly defined as idiopathic SAH (ISAH). Because of the negative angiography, limited extension of the bleeding with prevalent prepontine pattern and the benign prognosis, the venous causes has been preferred rather than the arterial ones. In the literature recent studies have suggested a possible contribution by primitive variants of Basal vein of Rosenthal (BVR) in its the pathogenesis of ISAH, commonly grouped according Watanabe classification (type A, B and C). In this paper we evaluated the prevalence of anatomical variants of BVR in ISAH.

Methods Venous drainage at angiography was retrospectively analyzed in 40 patients with ISAH and in 40 with unruptured aneurysms as controls.

Results and conclusions Previous studies displayed a significant prevalence of BVR type C variants in ISAH. Conversely in our study we recognized variant B as prevalent, in which the BVR bifurcates to drain anteriorly into the uncal vein and posteriorly into the Galenic system. Similarly to variant C (in which the BVR drains via perimesencephalic “bridging” veins into cavernous, sphenoparietal, petrosal sinus or directly into transverse sinus) also variant B might be subjected to those stress mechanisms and intrinsic system ‘fragility’ and for reasons yet to determine, sets off a consequent hemorrhage with clinical and radiological features typical of ISAH.

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Focused opening of the sylvian fissure for microsurgical management of MCA aneurysms

Focused opening of the sylvian fissure for microsurgical management of MCA aneurysms

Acta Neurochir (2014) 156:17–25

A wide sylvian opening, with either a proximal or distal start, has been standard for microsurgical management of middle cerebral artery (MCA) aneurysms. However, extensive sylvian dissection is potentially associated with increased incidence of iatrogenic injury to the brain and neurovascular structures. The aim of the present study was to describe the technique of focused opening of the sylvian fissure for microsurgical management of MCA aneurysms with additional tips on handling difficulties which may be encountered with this technique.

Method A 3D image-based anatomic orientation, clipping field–focused surgical planning, slack brain, and high magnification are the basic requirements for this approach. A 10– 15 mm sylvian opening is placed so that it allows safe access and a good surgical view of the MCA aneurysm clipping field. Under proximal control of the MCA, the aneurysm neck can be dissected and clipped effectively and safely, in this small surgical field.

Results The presented technique has been developed and refined by the senior author during the surgery of 1,097 aneurysms over the last 13 years. It has proved to be safe, and effective for clipping of both ruptured and unruptured MCA aneurysms. Its greatest advantages are a shorter operative time and less brain and vessel manipulation compared to more extensive approaches.

Conclusion The focused sylvian opening is a less-invasive alternative to the classical wide sylvian opening for the microsurgical management of most MCA aneurysms.

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Computational Fluid Dynamic Analysis of Intracranial Aneurysmal Bleb Formation

Computational Fluid Dynamic Analysis of Intracranial Aneurysmal Bleb Formation

Neurosurgery 73:1061–1069, 2013

The management of unruptured aneurysms is controversial, with the decision to treat influenced by aneurysm characteristics including size and morphology. Aneurysmal bleb formation is thought to be associated with an increased risk of rupture.

OBJECTIVE: To correlate computational fluid dynamic (CFD) indices with bleb formation.

METHODS: Anatomic models were constructed from 3-dimensional rotational angiography data in 27 patients with cerebral aneurysms harboring a single bleb. Additional models representing the aneurysm before bleb formation were constructed by digitally removing the bleb. We characterized hemodynamic features of models both with and without the blebs using CFDs. Flow structure, wall shear stress (WSS), pressure, and oscillatory shear index (OSI) were analyzed.

RESULTS: There was a statistically significant association between bleb location at or adjacent to the point of maximal WSS (74%, P = .019), irrespective of rupture status. Aneurysmal blebs were related to the inflow or outflow jet in 89% of cases (P < .001), whereas 11% were unrelated. Maximal wall pressure and OSI were not significantly related to bleb location. The bleb region attained a lower WSS after its formation in 96% of cases (P < .001) and was also lower than the average aneurysm WSS in 86% of cases (P < .001).

CONCLUSION: Cerebral aneurysm blebs generally form at or adjacent to the point of maximal WSS and are aligned with major flow structures. Wall pressure and OSI do not contribute to determining bleb location. The measurement of WSS using CFD models may potentially predict bleb formation and thus improve the assessment of rupture risk in unruptured aneurysms.

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Surgical Treatment of 127 Anterior Choroidal Artery Aneurysms

Anterior Choroidal Artery Aneurysms

Neurosurgery 73:933–940, 2013

The anterior choroidal artery (AChA) supplies important areas of the nervous system, particularly the posterior limb of the internal capsule and optic radiation. Treatment of AChA aneurysms poses particular challenges because of the complex anatomy of the aneurysm associated with the relatively small diameter of AChAs, making preservation of the parent vessel during clip ligation or endosaccular coiling challenging.

OBJECTIVE: To investigate the incidence and features of ischemia in treatment of AChA aneurysms.

METHODS: A prospectively maintained database of patients who underwent treatment of aneurysms from 1985 to 2011 was queried to find patients with AChA aneurysms. Age, sex, Hunt and Hess grade, treatment modality, and complications were analyzed by use of the unpaired Student t test and Fisher exact test.

RESULTS: One hundred twenty-two patients harbored 127 AChA aneurysms, and 67% (82 of 122) had multiple aneurysms. Treatment included 112 microsurgical clip ligations, 8 endosaccular coil embolizations, 5 aneurysmal wrappings, and 2 surgical explorations. Complications developed in 53% (67 of 127) of AChA aneurysms. Postoperative ischemia occurred in 12% (15 of 127) of treated aneurysms. The number of temporary clip applications was most closely associated with postoperative ischemia. Glasgow Outcome Scale scores of 4 or 5 were obtained by 78% at discharge, 89% at 6 months, and 85% at 1 year.

CONCLUSION: The ischemic complication rate from surgical treatment of AChA aneurysms is most closely associated with higher frequency of temporary clip applications for proximal control and may be lower than previously reported. Supplementary intraoperative tools and limitation of vessel manipulation should be used to improve outcomes.

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Long-term Follow-up of Blister Aneurysms of the Internal Carotid Artery

Blister ICA aneurysm

Neurosurgery 73:1026–1033, 2013

Blister aneurysms of the internal carotid artery (ICA) are uncommon. There is a paucity of data on the long-term outcomes of patients.

OBJECTIVE: To review our experience with the treatment of these lesions.

METHODS: We retrospectively reviewed all aneurysms treated at our institution between 1994 and 2005. Relevant operative notes, radiology reports, and inpatient/ outpatient records were reviewed.

RESULTS: Seventeen patients (3 male, 14 female) with 18 blister aneurysms of the ICA were identified. The mean age was 44.6 years (range, 17-72; median, 42 years). Twelve patients (70.6%) presented with aneurysmal subarachnoid hemorrhage. The mean admission Glasgow Outcome Scale score was 4.3 (range, 2-5; median, 5). All patients were initially treated using microsurgical technique with direct clipping (n = 15; 83.3%) or clip-wrapping with Gore-Tex (n = 3, 16.7%). There were 4 cases of intraoperative rupture, all associated with attempted direct clipping; all 4 cases were successfully clipped. Two cases rebled post-treatment. Both rebleeding episodes were managed with endovascular stenting. Follow-up angiography was available for 14 patients and revealed a new aneurysm adjacent to the site of clipping in 1 patient and in-stent stenosis in 2. At the mean follow-up of 74.5 months (median, 73; range, 7-165), the mean Glasgow Outcome Scale score was 4.6 (range, 2-5; median, 5).

CONCLUSION: Microsurgical treatment of blister aneurysms of the ICA results in excellent outcome. In the evolution of treating these friable aneurysms, we have modified our clip-wrapping technique and use this technique when direct clipping is not feasible.

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