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OBJECTIVE Aneurysms that arise on the medial surface of the paraclinoid segment of the internal carotid artery (ICA) are surgically challenging. The contralateral interoptic trajectory, which uses the space between the optic nerves, can partially expose the medial surface of the paraclinoid ICA. In this study, the authors quantitatively measure the area of the medial ICA accessible through the interoptic triangle and propose a potential patient-selection algorithm that is based on preoperative measurements on angiographic imaging. METHODS The contralateral interoptic trajectory was studied on 10 sides of 5 cadaveric heads, through which the medial paraclinoid ICA was identified. The falciform ligament medial to the contralateral optic canal was incised, the contralateral optic nerve was gently elevated, and the medial surface of the paraclinoid ICA was inspected via different viewing angles to obtain maximal exposure. The accessible area on the carotid artery was outlined. The distance from the distal dural ring (DDR) to the proximal and distal borders of this accessible area was measured. The superior and inferior borders were measured using the clockface method relative to a vertical line on the coronal plane. To validate these parameters, preoperative measurements and intraoperative findings were reviewed in 8 clinical cases. RESULTS In the sagittal plane, the mean (SD) distances from the DDR to the proximal and distal ends of the accessible area on the paraclinoid ICA were 2.5 (1.52) mm and 8.4 (2.32) mm, respectively. In the coronal plane, the mean (SD) angles of the superior and inferior ends of the accessible area relative to a vertical line were 21.7° (14.84°) and 130.9° (12.75°), respectively. Six (75%) of 8 clinical cases were consistent with the proposed patient-selection algorithm. CONCLUSIONS The contralateral interoptic approach is a feasible route to access aneurysms that arise from the medial paraclinoid ICA. An aneurysm can be safely clipped via the contralateral interoptic trajectory if 1) both proximal and distal borders of the aneurysm neck are 2.5–8.4 mm distal to the DDR, and 2) at least one border of the aneurysm neck on the coronal clockface is 21.7°–130.9° medial to the vertical line.

OBJECTIVEThe controversy continues over the clinical utility of preoperative embolization for reducing tumor vascularity of intracranial meningiomas prior to resection. Previous studies comparing embolization and nonembolization patients have not controlled for detailed tumor parameters before assessing outcomes.METHODSThe authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016. Propensity score matching was used to generate embolization and nonembolization cohorts of 52 patients each, and a retrospective review of clinical and radiological outcomes was performed.RESULTSIn total, 52 consecutive patients who underwent embolization (mean follow-up 34.8 ± 31.5 months) were compared to 52 patients who did not undergo embolization (mean follow-up 32.8 ± 28.7 months; p = 0.63). Variables controlled for included patient age (p = 0.82), tumor laterality (p > 0.99), tumor location (p > 0.99), tumor diameter (p = 0.07), tumor invasion into a major dural sinus (p > 0.99), and tumor encasement around the internal carotid artery or middle cerebral artery (p > 0.99). The embolization and nonembolization cohorts did not differ in terms of estimated blood loss during surgery (660.4 ± 637.1 ml vs 509.2 ± 422.0 ml; p = 0.17), Simpson grade IV resection (32.7% vs 25.0%; p = 0.39), perioperative procedural complications (26.9% vs 19.2%; p = 0.35), development of permanent new neurological deficits (5.8% vs 7.7%; p = 0.70), or favorable modified Rankin Scale (mRS) score (a score of 0–2) at last follow-up (96.0% vs 92.3%; p = 0.43), respectively. When comparing the final mRS score to the preoperative mRS score, patients in the embolization group were more likely than patients in the nonembolization group to have an improvement in mRS score (50.0% vs 28.8%; p = 0.03).CONCLUSIONSAfter controlling for patient age, tumor size, tumor laterality, tumor location, tumor invasion into a major dural sinus, and tumor encasement of the internal carotid artery or middle cerebral artery, preoperative meningioma embolization intended to decrease tumor vascularity did not improve the surgical outcomes of patients with WHO grade I intracranial meningiomas, but it did lead to a greater chance of clinical improvement compared to patients not treated with embolization.

OBJECTIVEThe pretemporal transcavernous approach (PTA) and the endoscopic endonasal transcavernous approach (EETA) are both used to access the retroclival region. A direct quantitative comparison of both approaches has not been made. The authors compared the technical nuances of, and surgical exposure afforded by, each approach and identified the key elements of the approach selection process.METHODSFourteen cadaveric specimens underwent either PTA (group A) or EETA with unilateral (group B) followed by bilateral (group C) interdural pituitary gland transposition. The percentage of drilled clivus; length of exposed oculomotor nerve (cranial nerve [CN] III), posterior cerebral artery (PCA), and superior cerebellar artery (SCA); and surgical area of exposure of both cerebral peduncles and the pons for the 3 groups were measured and compared.RESULTSGroup A had a significantly lower percentage of drilled area than group B (mean [SD], 35.6% [11.2%] vs 91.3% [4.9%], p < 0.01). In group C, 100% of the upper third of the clivus was drilled in all specimens. Significantly longer segments of the ipsilateral PCA (p < 0.01) and SCA (p < 0.01) were exposed in group A than in group B. There was no significant difference in the length of the ipsilateral CN III exposed among the 3 groups. There was also no significant difference between group A and either group B or group C for the contralateral CN III or PCA exposure. However, longer segments of the contralateral SCA were exposed in group C than in group A (p = 0.02). Furthermore, longer segments of CN III (p < 0.01), PCA (p < 0.01), and SCA (p < 0.01) were exposed in group C than in group B. For brainstem exposure, there was greater exposure of the pons in group C than in group A (mean [SD], 211.4 [19.5] mm2 vs 157.7 [25.3] mm2, p < 0.01) and group B (211.4 [19.5] mm2 vs 153.9 [34.1] mm2, p < 0.01). However, significantly greater exposure of the ipsilateral peduncle was observed in group A (mean [SD], 125.6 [43.1] mm2) than in groups B and C (56.3 [6.0] mm2, p < 0.01). Group C had significantly greater exposure of the contralateral peduncle than group B (p = 0.02).CONCLUSIONSThis study is the first to quantitatively identify the advantages and limitations of the PTA and EETA from an anatomical perspective. Understanding these data may help the skull base surgeon design a maximally effective yet minimally invasive approach to individual lesions.

Introduction Distal ophthalmic artery (OpA) aneurysms are a rare subset of vascular lesions with lack of optimal treatment. The management of these aneurysms may require complete occlusion of the parent vessel, carrying a risk of permanent visual impairment due to individual variations of extracranial collateral flow to the intraorbital ophthalmic artery (iOpA). Objective To test the feasibility of a superficial temporal artery (STA) to iOpA bypass to prevent acute ischemic retinal injury. Two different transorbital corridors (superomedial and posterolateral approaches) for this bypass were evaluated. Methods Each approach was carried out in 10 specimens each (n = 20). The corridors were compared to achieve the optimal exposure of the iOpA until the central retinal artery origin was visualized. An end-to-end anastomosis was performed from STA-to-iOpA. The arterial caliber and length at the anastomotic sites, required donor artery length, and intraorbital surgical area were measured. Results STA-iOpA bypasses were performed in all specimens. For the posterolateral transorbital approach, the mean caliber of STA was 1.8 ± 0.2 mm, and that of iOpA was 1.7 ± 0.5 mm. The required STA graft length was 78.3 ± 1 mm with lateral iOpA transposition of 8.2 ± 1.1 mm. For the superomedial approach, the average STA length required for an intraorbital bypass was 130.8 ± 14.0 mm. The mean calibers of iOpA and STA were 1.5 ± 0.1 mm and 1.5 ± 0.1 mm, respectively. Conclusions This study demonstrates the feasibility of a novel revascularization technique of the iOpA using 2 different transorbital approaches. These techniques can be used in the management of intraorbital lesions such as OpA aneurysms, tumoral infiltrations, or intraoperative injuries.

Background Surgical exposure of the V1 segment of the vertebral artery (V1-VA) at the lower neck may be necessary to address intravascular (atherosclerotic) and extravascular (external compression by neoplastic or degenerative) pathologies. The adjacent anatomy at the lower cervical region is complex and relatively unfamiliar to neurosurgeons compared to that of upper cervical levels. High-quality cadaveric images simulating the surgical approach to V1-VA are important for learning the relevant anatomy. Objective To provide a brief stepwise depiction of the exposure of the V1-VA using a cadaveric surgical simulation. Methods A cadaveric surgical simulation was performed on the left side to expose the V1-VA using the retrojugular and interjugular carotid approaches. The important adjacent anatomic structures en route to the V1-VA were identified. Results A stepwise photographic demonstration of the surgical exposure of the V1-VA is provided. Conclusion Exposure of the V1-VA can be challenging and requires a clear anatomic understanding of the relevant anatomy. The present work attempts to facilitate this objective.

Background No longitudinal, long-term, follow-up studies have explored the association between presence and severity of variations in extracranial venous anatomy, and clinical outcomes in patients with multiple sclerosis (MS). Objective This prospective 5-year follow-up study assessed the relationship of variations in extracranial venous anatomy, indicative of chronic cerebrospinal venous insufficiency (CCSVI) on Doppler sonography, according to the International Society for Neurovascular Disease (ISNVD) proposed consensus criteria, with clinical outcomes and disease progression in MS patients. Methods 90 MS patients (52 relapsing-remitting, RRMS and 38 secondary-progressive, SPMS) and 38 age- and sex-matched HIs were prospectively followed for 5.5 years. Extracranial and transcranial Doppler-based venous hemodynamic assessment was conducted at baseline and follow-up to determine the extent of variations in extracranial venous anatomy. Change in Expanded Disability Status Scale (∆EDSS), development of disability progression (DP) and annualized relapse rate (ARR) were assessed. Results No significant differences were observed in MS patients, based on their presence of variations in extracranial venous anatomy at baseline or at the follow-up, in ∆EDSS, development of DP or ARR. While more MS patients had ISNVD CCSVI criteria fulfilled at baseline compared to HIs (58% vs. 37%, p = 0.03), no differences were found at the 5-year follow-up (61% vs. 56%, p = 0.486). Discussion This is the longest follow-up study assessing the longitudinal relationship between the presence of variations in extracranial venous anatomy and clinical outcomes in MS patients. Conclusion: The presence of variations in extracranial venous anatomy does not influence clinical outcomes over the 5-year follow-up in MS patients. Electronic supplementary material The online version of this article (10.1186/s12883-019-1350-2) contains supplementary material, which is available to authorized users.

OBJECTIVEAccess to the ventrolateral pontomesencephalic area may be required for resecting cavernous malformations, performing revascularization of the upper posterior circulation, and treating vascular lesions such as aneurysms. However, such access is challenging because of nearby eloquent structures. Commonly used corridors to this surgical area include the optico-carotid, supracarotid, and carotid-oculomotor triangles. However, the window lateral to the oculomotor nerve can also be used and has not been studied. The authors describe the anatomical window formed between the oculomotor nerve and the medial tentorial edge (the oculomotor-tentorial triangle [OTT]) to the ventrolateral pontomesencephalic area, and assess techniques to expand it.METHODSFour cadaveric heads (8 sides) underwent orbitozygomatic craniotomy. The OTT was exposed via a pretemporal approach. The contents of the OTT were determined and their anatomical features were recorded. Also, dimensions of the brainstem surface exposed lateral and inferior to the oculomotor nerve were measured. Measurements were repeated after completing a transcavernous approach (TcA), and after resection of temporal lobe uncus (UnR).RESULTSThe s1 segment and proximal s2 segment of the superior cerebellar artery (SCA) and P2A segment of the posterior cerebral artery (PCA) were the main contents of the OTT, with average exposed lengths of 6.4 ± 1.3 mm and 5.5 ± 1.6 mm for the SCA and PCA, respectively. The exposed length of the SCA increased to 9.6 ± 2.7 mm after TcA (p = 0.002), and reached 11.6 ± 2.4 mm following UnR (p = 0.004). The exposed PCA length increased to 6.2 ± 1.6 mm after TcA (p = 0.04), and reached 10.4 ± 1.8 mm following UnR (p < 0.001). The brainstem surface was exposed 7.1 ± 0.5 mm inferior and 5.6 ± 0.9 mm lateral to the oculomotor nerve initially. The exposure inferior to the oculomotor nerve increased to 9.3 ± 1.7 mm after TcA (p = 0.003), and to 9.9 ± 2.5 mm after UnR (p = 0.21). The exposure lateral to the oculomotor nerve increased to 8.0 ± 1.7 mm after TcA (p = 0.001), and to 10.4 ± 2.4 mm after UnR (p = 0.002).CONCLUSIONSThe OTT is an anatomical window that provides generous access to the upper ventrolateral pontomesencephalic area, s1- and s2-SCA, and P2A-PCA. This window may be efficiently used to address various pathologies in the region and is considerably expandable by TcA and/or UnR.

The contralateral interhemispheric transprecuneus approach (CITP) and the supracerebellar transtentorial transcollateral sulcus approach (STTC) are 2 novel approaches to access the atrium of the lateral ventricle. We quantitatively compared the 2 approaches.Both approaches were performed in 6 sides of fixed and color-injected cadaver heads. We predefined the 6 targets in the atrium for measurement and standardization of the approaches. Using a navigation system, we quantitatively measured the working distance, cortical transgression, angle of attack, area of exposure, and surgical freedom.The distances from the craniotomy edge to the posterior pole of the choroid plexus of the CITP (mean ± standard deviation, 67 ± 5.3 mm) and STTC (mean, 57 ± 4.0 mm) differed significantly (P0.01). Cortical transgression with the CITP (mean, 27 ± 2.8 mm) was significantly greater than that with the STTC (mean, 21 ± 6.7 mm; P = 0.03). The CITP showed a significantly wider rostrocaudal angle of attack than that with the STTC (P = 0.01). The STTC showed a significantly wider mediolateral angle (P0.01). No significant difference was found for surgical freedom of any target except for point E, for which the CITP was larger. The exposure area did not differ significantly between the 2 approaches (P = 0.07).Both approaches were feasible for accessing the atrium. The STTC provided a shorter working distance and wider mediolateral angle, CITP provided a wider rostrocaudal angle of attack and better exposure and maneuverability to the anterior and superior atrium. In contrast, the STTC was more favorable for the inferior and posterior regions.

Background: The cognitive performance in multiple sclerosis (MS) patients declines with aging, longer disease duration, and possibly cardiovascular comorbidities. Objectives: We investigated whether lower total cerebral arterial blood flow (CABF) measured at the level of the carotid and vertebral arteries may contribute to worse cognitive performance in 132 MS patients and 47 healthy controls. Methods: Total CABF was evaluated with extracranial Doppler, whereas structural T2-lesion volume (LV) and gray matter volume (GMV) were measured on 3T MRI. The cognitive performance was assessed by Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test—Revised (BVMT-R), and California Verbal Learning Test—Second Edition (CVLT-II). Analysis of covariance, partial correlation, and regression models were used to test the differences between study groups and cognition/CABF correlations. False discovery rate (FDR)-corrected (Benjamini–Hochberg) p-values (i.e. q-values) less than 0.05 were considered significant. Results: Association between lower total CABF and the lower cognitive performance was observed only in MS patients ( r = 0.318, q 2 = 0.295, t-statistics = 2.538, standardized β = 0.203, and q = 0.020), but not with memory tests. Cognitively impaired MS patients had lower total CABF compared to cognitively preserved (884.5 vs 1020.2 mL/min, q = 0.008). Conclusion: Cognitively impaired MS patients presented with lower total CABF. Altered CABF may be a result of reduced metabolic rate and might contribute to abnormal cognitive aging in MS.

BACKGROUND Use of the far lateral transcondylar (FL) approach and vagoaccessory triangle is the standard exposure for clipping most posterior inferior cerebellar artery (PICA) aneurysms. However, a distal PICA origin or high-lying vertebrobasilar junction can position the aneurysm beyond the vagoaccessory triangle, making the conventional FL approach inappropriate. OBJECTIVE To demonstrate the utility of the extended retrosigmoid (eRS) approach and a lateral trajectory through the glossopharyngo-cochlear triangle as the surgical corridor for these cases. METHODS High-riding PICA aneurysms treated by microsurgery were retrospectively reviewed, comparing exposure through the eRS and FL approaches. Clinical, surgical, and outcome measures were evaluated. Distances from the aneurysm neck to the internal auditory canal (IAC), jugular foramen, and foramen magnum were measured. RESULTS Six patients with PICA aneurysms underwent clipping using the eRS approach; 5 had high-riding PICA aneurysms based on measurements from preoperative computed tomography angiography (CTA). Mean distances of the aneurysm neck above the foramen magnum, below the IAC, and above the jugular foramen were 27.0 mm, 3.7 mm, and 8.2 mm, respectively. Distances were all significantly lower versus the comparison group of 9 patients with normal or low-riding PICA aneurysms treated using an FL approach (P

Background Anterior cerebral artery (ACA) bypasses for complex aneurysms are infrequently performed, yet previous experience demonstrates the importance of intracranial-intracranial bypasses. Here we describe technical advances in intracranial-intracranial bypass techniques and their clinical results. Methods Twenty-three patients with complex aneurysms requiring ACA bypasses were retrospectively studied. Ten patients were treated in period 1 (1997–2013) and 13 in period 2 (2014–2018). Results There were 3 precommunicating, 8 communicating, and 8 postcommunicating ACA aneurysms, plus 4 middle cerebral artery aneurysms. ACA in situ bypass was the most commonly performed (9 patients; 39%). The classic left A3 ACA–right A3 ACA in situ bypass was performed in 5 patients, but 3 new in situ variations emerged in period 2: left pericallosal artery (PcaA)–right PcaA (n = 1), left callosomarginal artery (CmaA)–right CmaA (n = 2), and left CmaA–right A3 ACA (n = 1). The sole reimplantation in period 1 was the ipsilateral and vertical PcaA-CmaA reimplantation, whereas reimplantations in period 2 were contralateral and horizontal (left PcaA–right PcaA and right A3 ACA–left anterior internal frontal artery). The A1 ACA was used as a donor only in period 2 in 4 patients with middle cerebral artery bifurcation aneurysms. Bypass patency was 91%, and 21 patients (91%) improved or remained at neurologic baseline (mean [standard deviation] follow-up duration, 26 [8.2] months). Conclusions ACA bypass techniques continue to evolve with the addition of several variations. These variations push bypass techniques beyond the standard constructs and add important alternatives to our bypass arsenal.

OBJECTIVERecently, the prognostic value of the Simpson resection grading scale has been called into question for modern meningioma surgery. In this study, the authors analyzed the relationship between Simpson resection grade and meningioma recurrence in their institutional experience.METHODSThis study is a retrospective review of all patients who underwent resection of a WHO grade I intracranial meningioma at the authors’ institution from 2007 to 2017. Binary logistic regression analysis was used to assess for predictors of Simpson grade IV resection and postoperative neurological morbidity. Cox multivariate analysis was used to assess for predictors of tumor recurrence. Kaplan-Meier analysis and log-rank tests were used to assess and compare recurrence-free survival (RFS) of Simpson resection grades, respectively.RESULTSA total of 492 patients with evaluable data were included for analysis, including 394 women (80.1%) and 98 men (19.9%) with a mean (SD) age of 58.7 (12.8) years. The tumors were most commonly located at the skull base (n = 302; 61.4%) or the convexity/parasagittal region (n = 139; 28.3%). The median (IQR) tumor volume was 6.8 (14.3) cm3. Simpson grade I, II, III, or IV resection was achieved in 105 (21.3%), 155 (31.5%), 52 (10.6%), and 180 (36.6%) patients, respectively. Sixty-three of 180 patients (35.0%) with Simpson grade IV resection were treated with adjuvant radiosurgery. In the multivariate analysis, increasing largest tumor dimension (p < 0.01) and sinus invasion (p < 0.01) predicted Simpson grade IV resection, whereas skull base location predicted neurological morbidity (p = 0.02). Tumor recurrence occurred in 63 patients (12.8%) at a median (IQR) of 36 (40.3) months from surgery. Simpson grade I resection resulted in superior RFS compared with Simpson grade II resection (p = 0.02), Simpson grade III resection (p = 0.01), and Simpson grade IV resection with adjuvant radiosurgery (p = 0.01) or without adjuvant radiosurgery (p < 0.01). In the multivariate analysis, Simpson grade I resection was independently associated with no tumor recurrence (p = 0.04). Simpson grade II and III resections resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01) but similar RFS compared with Simpson grade IV resection with adjuvant radiosurgery (p = 0.82). Simpson grade IV resection with adjuvant radiosurgery resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01).CONCLUSIONSThe Simpson resection grading scale continues to hold substantial prognostic value in the modern neurosurgical era. When feasible, Simpson grade I resection should remain the goal of intracranial meningioma surgery. Simpson grade IV resection with adjuvant radiosurgery resulted in similar RFS compared with Simpson grade II and III resections.

Objective Because the clinical course of spontaneous aneurysmal subarachnoid hemorrhage (aSAH) can be compromised by pulmonary complications, we sought to review posttreatment outcomes in aSAH patients with and without pulmonary complications. Methods Patient demographic, clinical, and outcome data (March 2003–January 2007) were analyzed retrospectively. Patients underwent microsurgical or endovascular treatment for aSAH; pulmonary complications were reported. Outcomes were assessed using the Glasgow Outcome Scale (GOS) scores at the 1-year, 3-year, and 6-year follow-up visits. Results The cohort comprised 471 patients (mean age, 53.7 ± 12.4 years; men, 332/471 [70%]). The mean Glasgow Coma Scale (GCS) score at presentation was 11.9 ± 3.0. Of 471 patients, 47% (n = 223) presented with a Hunt and Hess score of ≥3 and 76% (n = 357) with a Fisher grade of 3. Treatment was clipping for 69% (279/407) and coiling for 31% (128/407) of patients. Pulmonary complications occurred in 210 of 471 (45%) patients. Nearly one-half of patients were discharged to home (215/471, 46%), and more than one-half had a good outcome defined as a GOS score of 5 at their 1-year (226/403, 56%), 3-year (217/397, 55%), and 6-year (203/380, 53%) follow-up visits. Logistic regression showed age and GCS scores as outcome predictors at all time points, whereas pulmonary complications predicted poor outcome only at the 1-year follow-up visit. Conclusions Pulmonary problems represent the most common nonneurologic medical complications after aSAH. Despite advances in critical care, pulmonary complications represented predictors of short-term poor outcome only at the 1-year follow-up visit, whereas the medical history of the patient became more relevant for prognosis in long-term follow-up.

Background The side-to-side anastomosis is one of the difficult bypass configurations that may be used in various complex cerebral vascular and neoplastic cases. Few pure arterial models exist for practicing this bypass subtype. Objective To provide an optimized side-to-side anastomosis training model using rat common carotid arteries (CCA). Methods Bilateral CCAs were exposed in the neck of 10 anesthetized Sprague-Dawley rats. The arteries were juxtaposed in parallel, using temporary aneurysm clips applied proximally and distally. CCA caliber and the length of CCA juxtaposition were measured. Side-to-side anastomosis was completed and ischemia time was recorded. Unintended complications were recorded for further analysis. Results Anastomosis was completed successfully in all animals. The CCAs were approximated in all animals without any difficulty or undue tension. In 2 rats, death occurred prior to completion of anastomosis, which was attributed to injury to the external jugular vein during vessel exposure. Mean ischemia time was 35 min with an average of 22 sutures done to complete the anastomosis. The average CCA caliber was 1.1 ± 0.2 mm and the arteries could be juxtaposed for an average length of 10.2 ± 1.5 mm. Conclusion Full exposure of the cervical segment of the CCAs enables tension-free approximation of adequate length of the vessel for a side-to-side anastomosis. Avoiding complications during exposure helps in prevention of animal death during the ischemia period.

Background Animal models are commonly used in training protocols for microsurgical vascular anastomosis. Rat common carotid arteries (CCAs) are frequently used for this purpose. Much attention has been paid to the technical details of various anastomosis configurations using these arteries. However, technical nuances of exposing rat CCAs have been understudied. The purpose of this study is to describe nuances of technique for safely and efficiently exposing rat CCAs in preparation for a vascular anastomosis. Methods Bilateral CCAs were exposed and prepared for anastomosis in 10 anesthetized Sprague-Dawley rats through a midline cervical incision. The exposed length of the CCA was measured. Additionally, technical nuances of exposure and surgically relevant anatomic details were recorded. Results The CCAs were exposed from the sternoclavicular joint to their bifurcation (average length, 19.1 ± 2.8 mm). Tenets important for a safe and efficient exposure of the CCAs included 1) generous subcutaneous dissection to expose the external jugular veins (EJVs), 2) avoiding injury to or compression of the EJVs, 3) superior mobilization of the salivary glands, 4) division of internal jugular veins, 5) opening the carotid sheath at its midlevel and from medial to lateral, and 6) avoiding injury to the vagus nerve or sympathetic trunk. Conclusions Using the principles introduced in this study, trainees may safely and efficiently expose rat CCAs in preparation for a bypass.

BACKGROUND Surgical resection of cavernous malformations (CM) in the posterior thalamus, pineal region, and midbrain tectum is technically challenging owing to the presence of adjacent eloquent cortex and critical neurovascular structures. Various supracerebellar infratentorial (SCIT) approaches have been used in the surgical armamentarium targeting lesions in this region, including the median, paramedian, and extreme lateral variants. Surgical view of a posterior thalamic CM from the traditional ipsilateral vantage point may be obscured by occipital lobe and tentorium. OBJECTIVE To describe a novel surgical approach via a contralateral SCIT (cSCIT) trajectory for resecting posterior thalamic CMs. METHODS From 1997 to 2017, 75 patients underwent the SCIT approach for cerebrovascular/oncologic pathology by the senior author. Of these, 30 patients underwent the SCIT approach for CM resection, and 3 patients underwent the cSCIT approach. Historical patient data, radiographic features, surgical technique, and postoperative neurological outcomes were evaluated in each patient. RESULTS All 3 patients presented with symptomatic CMs within the right posterior thalamus with radiographic evidence of hemorrhage. All surgeries were performed in the sitting position. There were no intraoperative complications. Neuroimaging demonstrated complete CM resection in all cases. There were no new or worsening neurological deficits or evidence of rebleeding/recurrence noted postoperatively. CONCLUSION This study establishes the surgical feasibility of a contralateral SCIT approach in resection of symptomatic thalamic CMs It demonstrates the application for this procedure in extending the surgical trajectory superiorly and laterally and maximizing safe resectability of these deep CMs with gravity-assisted brain retraction.

BACKGROUND Surgical resection of cavernous malformations (CM) in the posterior thalamus, pineal region, and midbrain tectum is technically challenging owing to the presence of adjacent eloquent cortex and critical neurovascular structures. Various supracerebellar infratentorial (SCIT) approaches have been used in the surgical armamentarium targeting lesions in this region, including the median, paramedian, and extreme lateral variants. Surgical view of a posterior thalamic CM from the traditional ipsilateral vantage point may be obscured by occipital lobe and tentorium. OBJECTIVE To describe a novel surgical approach via a contralateral SCIT (cSCIT) trajectory for resecting posterior thalamic CMs. METHODS From 1997 to 2017, 75 patients underwent the SCIT approach for cerebrovascular/oncologic pathology by the senior author. Of these, 30 patients underwent the SCIT approach for CM resection, and 3 patients underwent the cSCIT approach. Historical patient data, radiographic features, surgical technique, and postoperative neurological outcomes were evaluated in each patient. RESULTS All 3 patients presented with symptomatic CMs within the right posterior thalamus with radiographic evidence of hemorrhage. All surgeries were performed in the sitting position. There were no intraoperative complications. Neuroimaging demonstrated complete CM resection in all cases. There were no new or worsening neurological deficits or evidence of rebleeding/recurrence noted postoperatively. CONCLUSION This study establishes the surgical feasibility of a contralateral SCIT approach in resection of symptomatic thalamic CMs It demonstrates the application for this procedure in extending the surgical trajectory superiorly and laterally and maximizing safe resectability of these deep CMs with gravity-assisted brain retraction.

Background Animal models using rodents are frequently used for practicing microvascular anastomosis—an essential technique in cerebrovascular surgery. However, safely and efficiently exposing rat's target vessels is technically difficult. Such difficulty may lead to excessive hemorrhage and shorten animal survival. This limits the ability to perform multiple anastomoses on a single animal and may increase the overall training time and costs. We report our model for microsurgical bypass training in rodents in 2 consecutive articles. In part 1, we describe the technical nuances for a safe and efficient exposure of the rat abdominal aorta and common iliac arteries (CIAs) for bypass. Methods Over a 2-year period, 50 Sprague–Dawley rats underwent inhalant anesthesia for practicing microvascular anastomosis on the abdominal aorta and CIAs. Lessons learned regarding the technical nuances of vessel exposure were recorded. Results Several technical nuances were important for avoiding intraoperative bleeding and preventing animal demise while preparing an adequate length of vessels for bypass. The most relevant technical nuances include (1) generous subcutaneous dissection; (2) use of cotton swabs for the blunt dissection of the retroperitoneal fat; (3) combination of sharp and blunt dissection to isolate the aorta and iliac arteries from the accompanying veins; (4) proper control of the posterior branches of the aorta; and (5) efficient division and mobilization of the left renal pedicle. Conclusions Applying the aforementioned technical nuances enables safe and efficient preparation of the rat abdominal aorta and CIAs for microvascular anastomosis.

In situ bypasses to the anterior inferior cerebellar artery (AICA) are unusual because, with only one artery in the cerebellopontine angle (CPA), no natural intracranial donors parallel its course. In rare cases, the posterior inferior cerebellar artery (PICA) may have the tortuosity or redundancy to be mobilized to the AICA to serve as a donor. This video demonstrates this p3 PICA-to-a3 AICA in situ side-to-side bypass. A 75-yr-old woman presented with ataxia and hemiparesis from a large thrombotic right AICA aneurysm compressing the brainstem. Strategy consisted of bypass, trapping, and brainstem decompression. Written informed consent for surgery was obtained from the patient. A hockey-stick incision was made to harvest the occipital artery as a backup donor, but its diminutive caliber precluded its use. The bypass was performed through an extended retrosigmoid craniotomy. The aneurysm was trapped completely and thrombectomized to relieve the pontine mass effect. Indocyanine green videoangiography confirmed patency of the bypass, retrograde filling of the AICA to supply pontine perforators, and no residual aneurysmal filling. This unusual in situ bypass is possible when redundancy of the AICA and PICA allow their approximation in the CPA. The anastomosis is performed lateral to the lower cranial nerves in a relatively open and superficial plane. The extended retrosigmoid approach provides adequate exposure for both the bypass and aneurysm trapping. In situ AICA-PICA bypass enables anterograde and retrograde AICA revascularization with side-to-side anastomosis. The occipital artery-to-AICA bypass and the V3 vertebral artery-to-AICA interpositional bypass are alternatives when intracranial anatomy is unfavorable for this in situ bypass.1-6 Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Extracranial vertebral artery (VA) atherosclerosis is responsible for 14% to 32% of posterior circulation infarctions.1 In the posterior circulation, narrowing of the VA > 30% is significantly associated with strokes. Subclavian artery (SCA) atherosclerosis can produce subclavian steal. Retrograde VA flow around an occluded SCA decreases blood flow to the posterior circulation and causes vertebrobasilar insufficiency (VBI). Flow augmentation to the posterior circulation can be achieved by VA endarterectomy, arterial stenting, VA-common carotid artery (CCA) transposition, or bypass using an interposition graft.2,3 This video illustrates microsurgical revascularization of the proximal VA with VA-CCA transposition. A 58-yr-old man with a prior stroke and chronic right VA occlusion presented with dysarthria and gait instability. Angiographic evaluation confirmed complete midcervical right VA occlusion and left SCA occlusion proximal to VA origin, with subclavian steal. After obtaining patient consent and a failed attempt at endovascular recanalization of the left SCA, a left VA-CCA end-to-side transposition was performed. Neck dissection exposed the left CCA. The thyrocervical trunk served as a landmark to identify the SCA, which was traced proximally to the VA origin. After proximal occlusion, the VA was transected and "fish-mouthed" for end-to-side anastomosis to CCA. An intraluminal, continuous suture technique was used to sew the back walls of this anastomosis. Postoperative computed tomography angiography confirmed bypass patency. Collateral circulation through the thyrocervical and costocervical trunks likely supplied the left arm, and no cerebral, or limb, ischemic symptoms were noted on follow-up. VA-CCA transposition is an uncommon technique for safe and effective revascularization of symptomatic, medically refractory VBI caused by VA occlusion or, as in this case, SCA occlusion with secondary subclavian steal. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Indocyanine green videoangiography (ICG-VA) is a near-infrared range fluorescent marker used for intraoperative real-time assessment of flow in cerebrovascular surgery. Given its high spatial and temporal resolution, ICG-VA has been widely established as a useful technique to perform a qualitative analysis of the graft patency during revascularization procedures. In addition, this fluorescent modality can also provide valuable qualitative and quantitative information regarding the cerebral blood flow within the bypass graft and in the territories supplied. Digital subtraction angiography (DSA) is considered to be the gold standard diagnostic modality for postoperative bypass graft patency assessment. However, this technique is time and labor intensive and an expensive interventional procedure. In contrast, ICG-VA can be performed intraoperatively with no significant addition to the total operative time and, when used correctly, can accurately show acute occlusion. Such time-sensitive ischemic injury detection is critical for flow reestablishment through direct surgical management. In addition, ICG has an excellent safety profile, with few adverse events reported in the literature. This review outlines the chemical behavior, technical aspects, and clinical implications of this tool as an intraoperative adjunct in revascularization procedures.

Background: Fluorescein sodium (FNa) is a fluorescent drug with a long history of use for assessing retinal blood flow in ophthalmology; however, its application in vascular neurosurgery is only now gaining popularity. This review summarizes the current knowledge about using FNa videoangiography in vascular neurosurgery. Methods: We performed a literature review on the usage of FNa for fluorescent videoangiography procedures in neurosurgery. We analyzed methods of injection, dosages of FNa, visualizing platforms, and interpretation of FNa videoangiography. We also reviewed practical applications of FNa videoangiography during various vascular neurosurgeries. Results: FNa videoangiography can be performed with intraarterial (intracarotid) or intravenous dye injections. Both methods provide excellent resolution with enhanced fluorescence that shows intravascular blood flow on top of visible surrounding anatomy, and both allow simultaneous purposeful microsurgical manipulations. Although it is invasive, an intracarotid FNa injection results in faster contrast appearance and higher-intensity fluorescence and requires a lower dose per injection (reported range, 1–50 mg) compared with peripheral intravenous FNa injection (reported range, 75–2,000 mg or 1–1.5 mg/kg body weight). Four optical excitation/detection tools for FNa videoangiography have been successfully used: conventional xenon-light operating microscope with a special filter set, pencil-type light-emitting diode probe with a filter set, laser-illumination operating microscope, and an endoscope with a filter set. FNa videoangiography was reported to be feasible and useful in various clinical scenarios, such as examining the feeders and drainers in arteriovenous malformation surgery, checking the patency of a microvascular anastomosis, and assessing blood flow during aneurysm clipping. FNa videoangiography can be repeated during the same procedure and used along with indocyanine green (ICG) videoangiography. Conclusions: Compared with ICG videoangiography, FNa videoangiography has the advantages of enabling real-time inspection and better visualization at deep locations; however, thick vessel walls limit visualization of FNa in larger vessels. FNa videoangiography is a useful tool in multiple neurovascular scenarios and merits further studies to establish its clinical value.

Background: High-grade glioma (HGG) is associated with a dismal prognosis despite significant advances in adjuvant therapies, including chemotherapy, immunotherapy, and radiotherapy. Extent of resection continues to be the most important independent prognosticator of survival. This underlines the significance of increasing gross total resection (GTR) rates by using adjunctive intraoperative modalities to maximize resection with minimal neurological morbidity. 5-aminolevulinic acid (5-ALA) is the only US Food and Drug Administration–approved intraoperative optical agent used for fluorescence-guided surgical resection of gliomas. Despite several studies on the impact of intra-operative 5-ALA use on the extent of HGG resection, a clear picture of how such usage affects patient survival is still unavailable.Methods: A systematic review was conducted of all relevant studies assessing the GTR rate and survival outcomes [overall survival (OS) and progression-free survival (PFS)] in HGG. A meta-analysis of eligible studies was performed to assess the influence of 5-ALA-guided resection on improving GTR, OS, and PFS. GTR was defined as >95% resection.Results: Of 23 eligible studies, 19 reporting GTR rates were included in the meta-analysis. The pooled cohort had 998 patients with HGG, including 796 with newly diagnosed cases. The pooled GTR rate among patients with 5-ALA–guided resection was 76.8% (95% confidence interval, 69.1–82.9%). A comparative subgroup analysis of 5-ALA–guided vs. conventional surgery (controlling for within-study covariates) showed a 26% higher GTR rate in the 5-ALA subgroup (odds ratio, 3.8; P < 0.001). There were 11 studies eligible for survival outcome analysis, 4 of which reported PFS. The pooled mean difference in OS and PFS was 3 and 1 months, respectively, favoring 5-ALA vs. control (P < 0.001).Conclusions: This meta-analysis shows a significant increase in GTR rate with 5-ALA–guided surgical resection, with a higher weighted GTR rate (~76%) than the pivotal phase III study (~65%). Pooled analysis showed a small yet significant increase in survival measures associated with the use of 5-ALA. Despite the statistically significant results, the low level of evidence and heterogeneity across these studies make it difficult to conclusively report an independent association between 5-ALA use and survival outcomes in HGG. Additional randomized control studies are required to delineate the role of 5-ALA in survival outcomes in HGG.

Background The anatomico-functional complexity of the ophthalmic segment aneurysms is attributable to the presence of critical neurovascular structures in the surgical field. Surgical clipping of the ophthalmic artery (OpA) aneurysms can result in postoperative visual deficit due to the complexity of the aneurysm, vasospasm, or optic nerve manipulation. In this study, we aimed to characterize the feasibility of an intracanalicular OpA (iOpA) revascularization with 2 donor vessels: an intracranial-intracranial (IC-IC) bypass using the anterior temporal artery (ATA) and an extracranial-intracranial (EC-IC) bypass using the superficial temporal artery (STA). We further discuss their potential role in “unclippable” OpA aneurysms. Methods Twenty cadaveric specimens were used to evaluate the operative exposure of the intradural and intracanalicular OpA segments using an extradural-intradural intracanalicular approach. The arterial caliber and length at the anastomotic sites and required donor artery lengths were measured. The feasibility of the bypass using both donors was assessed. Results The average length of the intradural and intracanalicular segment of the OpA was 9.5 ± 1.6 mm. The mean caliber of the iOpA was 1.5 ± 0.2 mm. The mean ATA length required for an ATA-OpA anastomosis was 26.7 ± 8.9 mm, with a mean caliber of 1.0 ± 0.1 mm. The mean length of STA required for the bypass was 89.9 ± 9.7 mm, with a mean caliber of 1.92 ± 0.4 mm. Conclusions This study confirms the feasibility of iOpA revascularization using IC-IC and EC-IC bypasses. These techniques could potentially be used for prophylactic or therapeutic neuroprotection from retinal ischemic injury while treating complex OpA aneurysms, infiltrative tumors, or intraoperative arterial injuries.

OBJECTIVEThe cisternal pulvinar is a challenging location for neurosurgery. Four approaches for reaching the pulvinar without cortical transgression are the ipsilateral supracerebellar infratentorial (iSCIT), contralateral supracerebellar infratentorial (cSCIT), ipsilateral occipital transtentorial (iOCTT), and contralateral occipital transtentorial/falcine (cOCTF) approaches. This study quantitatively compared these approaches in terms of surgical exposure and maneuverability.METHODSEach of the 4 approaches was performed in 4 cadaveric heads (8 specimens in total). A 6-sided anatomical polygonal region was configured over the cisternal pulvinar, defined by 6 reachable anatomical points in different vectors. Multiple polygons were subsequently formed to calculate the areas of exposure. The surgical freedom of each approach was calculated as the maximum allowable working area at the proximal end of a probe, with the distal end fixed at the posterior pole of the pulvinar. Areas of exposure, surgical freedom, and the working distance (surgical depth) of all approaches were compared.RESULTSNo significant difference was found among the 4 different approaches with regard to the surgical depth, surgical freedom, or medial exposure area of the pulvinar. In the pairwise comparison, the cSCIT approach provided a significantly larger lateral exposure (39 ± 9.8 mm2) than iSCIT (19 ± 10.3 mm2, p < 0.01), iOCTT (19 ± 8.2 mm2, p < 0.01), and cOCTF (28 ± 7.3 mm2, p = 0.02) approaches. The total exposure area with a cSCIT approach (75 ± 23.1 mm2) was significantly larger than with iOCTT (43 ± 16.4 mm2, p < 0.01) and iSCIT (40 ± 20.2 mm2, p = 0.01) approaches (pairwise, p ≤ 0.01).CONCLUSIONSThe cSCIT approach is preferable among the 4 compared approaches, demonstrating better exposure to the cisternal pulvinar than ipsilateral approaches and a larger lateral exposure than the cOCTF approach. Both contralateral approaches described (cSCIT and cOCTF) provided enhanced lateral exposure to the pulvinar, while the cOCTF provided a larger exposure to the lateral portion of the pulvinar than the iOCTT. Medial exposure and maneuverability did not differ among the approaches. A short tentorium may negatively impact an ipsilateral approach because the cingulate isthmus and parahippocampal gyrus tend to protrude, in which case they can obstruct access to the cisternal pulvinar ipsilaterally.

BACKGROUND Three-dimensional (3D) printing holds great potential for lateral skull base surgical training; however, studies evaluating the use of 3D-printed models for simulating transtemporal approaches are lacking. OBJECTIVE To develop and evaluate a 3D-printed model that accurately represents the anatomic relationships, surgical corridor, and surgical working angles achieved with increasingly aggressive temporal bone resection in lateral skull base approaches. METHODS Cadaveric temporal bones underwent thin-slice computerized tomography, and key anatomic landmarks were segmented using 3D imaging software. Corresponding 3D-printed temporal bone models were created, and 4 stages of increasingly aggressive transtemporal approaches were performed (40 total approaches). The surgical exposure and working corridor were analyzed quantitatively, and measures of face validity, content validity, and construct validity in a cohort of 14 participants were assessed. RESULTS Stereotactic measurements of the surgical angle of approach to the mid-clivus, residual bone angle, and 3D-scanned infill volume demonstrated comparable changes in both the 3D temporal bone models and cadaveric specimens based on the increasing stages of transtemporal approaches (PANOVA

OBJECTIVEMeningiomas at the falcotentorial junction represent a rare subgroup of complex meningiomas. Debate remains regarding the appropriate treatment strategy for and optimal surgical approach to these tumors, and surgical outcomes have not been well described in the literature. The authors reviewed their single-institution experience in the management, approach selection, and outcomes for patients with falcotentorial meningiomas.METHODSFrom the medical records, the authors identified all patients with falcotentorial meningiomas treated with resection at the Barrow Neurological Institute between January 2007 and October 2017. Perioperative clinical, surgical, and radiographic data were retrospectively collected. For patients who underwent the supracerebellar infratentorial approach, the tentorial angle was defined as the angle between the line joining the nasion with the tuberculum sellae and the tentorium in the midsagittal plane.RESULTSFalcotentorial meningiomas occurred in 0.97% (14/1441) of the patients with meningiomas. Most of the patients (13/14) were female, and the mean patient age was 59.8 ± 11.3 years. Of 17 total surgeries (20 procedures), 11 were single-stage primary surgeries, 3 were two-stage primary surgeries (6 procedures), 2 were reoperations for recurrence, and 1 was a reoperation after surgery had been aborted because of brain edema. Hydrocephalus was present in 5 of 17 cases, 4 of which required additional treatment. Various approaches were used, including the supracerebellar infratentorial (4/17), occipital transtentorial/transfalcine (4/17), anterior interhemispheric transsplenial (3/17), parietal transventricular (1/17), torcular (2/17), and staged supracerebellar infratentorial and occipital transtentorial/transfalcine (3/17) approaches. Of the 17 surgeries, 9 resulted in Simpson grade IV resection, and 3, 1, and 4 surgeries resulted in Simpson grades III, II, and I resection, respectively. The tentorial angle in cases with Simpson grade I resection was significantly smaller than in those with an unfavorable resection grade (43.3° ± 4.67° vs 54.0° ± 3.67°, p = 0.04). Complications occurred in 10 of 22 approaches (17 surgeries) and included visual field defects (6 cases, 2 permanent and 4 transient), hemiparesis (2 cases), hemidysesthesia (1 case), and cerebellar hematoma (1 case).CONCLUSIONSFalcotentorial meningiomas are challenging lesions. A steep tentorial angle is an unfavorable preoperative radiographic factor for achieving maximal resection with the supracerebellar infratentorial approach. Collectively, the study findings show that versatility is required to treat patients with falcotentorial meningiomas and that treatment goals and surgical approach must be individualized to obtain optimal surgical results.

Natalizumab is an efficacious monoclonal antibody approved for use in relapsing-remitting multiple sclerosis (RRMS). Multiple studies have demonstrated reduced relapse rate, decreased disability progression and prolonged disease-free intervals with natalizumab use. However, natalizumab is associated with an increased risk of progressive multifocal leukoencephalopathy (PML), thus restricting its widespread use with populations at high risk for developing PML. Recently, the effect of natalizumab in secondary-progressive (SPMS) population has been explored.This review highlights the pathophysiology behind disease progression in MS and summarizes various attributes of natalizumab including: its pharmacological properties and global economic impact, results of clinical efficacy studies, its role in SPMS, pregnancy and its adverse events profile including PML and discontinuation protocols.Despite an established role in reducing RRMS disease activity, natalizumab has found limited use in SPMS due to insufficient evidence of efficacy. Current disease-modifying therapies exert modest overall benefit in SPMS owing to its complex pathophysiology, higher prevalence of comorbidities and increased PML risk with age and lack of reliable outcome measures. Finding more appropriate MRI and clinical outcome measures is quintessential for designing future randomized trials and possibly exploring primary neuroprotective agents for treating SPMS.

Lateral medullary arteriovenous malformations (AVMs) are located in the pia on the lateral medullary surface.1 They are supplied by arterial feeders from the V4 segment of the vertebral artery or posterior inferior cerebellar artery. A 64-yr-old man presented with leg spasms and progressively worsening gait. Angiography demonstrated a lateral medullary AVM. Patient consent was obtained for the surgical treatment of this lesion. Owing to its eloquent location, an occlusion in situ was performed without resection.1,2 This technique relies on the interruption of the arterial blood supply and occlusion of the draining vein to occlude the AVM. Intraoperative neurophysiological monitoring of motor and somatosensory evoked potentials was used, and the elimination of arteriovenous shunt flow was confirmed using indocyanine green videoangiography. Occlusion in situ preserves the flow to the delicate brainstem perforators and is safer than resection in selected cases like this one. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

The superficial temporal artery to middle cerebral artery (STA-MCA) bypass is the most common bypass for augmenting or restoring cerebral blood flow. Although the single-barrel (SB) STA-MCA bypass is sufficient in most cases, the double-barrel (DB) STA-MCA bypass can supply the demands of different vascular territories or multiple efferent arteries. We present a comparative analysis of SB and DB STA-MCA bypass in a large, consecutive series to examine indications, surgical results, and patient outcomes.A retrospective review of a prospectively maintained database identified all STA-MCA bypasses performed by a single surgeon over 21 years.In total, 261 patients received 378 STA-MCA bypasses in 351 surgeries. SB STA-MCA bypasses were performed in 234 patients (90%), whereas DB STA-MCA bypasses were performed in 27 patients (10%). Patients with DB STA-MCA bypasses were more likely to undergo bilateral bypass procedures than those receiving SB STA-MCA bypass (P0.0001). In patients with bilateral STA-MCA bypasses (n = 91, 35%), 69 patients received bilateral SB STA-MCA bypasses (76%), whereas 22 patients received a DB STA-MCA bypass on 1 hemisphere (24%). There was no difference in bypass patency or clinical outcome in patients with SB and DB STA-MCA bypasses.DB STA-MCA bypasses are reserved for patients requiring revascularization of multiple vascular territories or efferent arteries. DB STA-MCA bypasses have patency rates and patient outcomes comparable to SB STA-MCA, with the advantages of a single incision and reduced operative complexity compared to high-flow bypasses. DB STA-MCA bypass is an important element in the vascular neurosurgeon's bypass armamentarium.

Over the last few decades, cerebrovascular surgery has gravitated towards a minimally invasive philosophy without compromising the foundational principles of patient safety and surgical efficacy. Enhanced radiosurveillance modalities and increased average life expectancy have resulted in an increased reported incidence of intracranial aneurysms. Although endovascular therapies have gained popularity in the recent years, microsurgical clipping continues to be of value in the management of these aneurysms owing to its superior occlusion rates, applicability to complex aneurysms and reduced retreatment rates. The concept of keyhole transcranial procedures has advanced the field significantly leading to decreased postoperative neurological morbidity and quicker recovery. The main keyhole neurosurgical approaches include the supraorbital craniotomy (SOC), lateral supraorbital craniotomy (LSOC), mini-pterional craniotomy (MPTC), mini-orbitozygomatic craniotomy and the mini anterior interhemispheric approach (MAIA). As these minimally invasive approaches can have an inherent limitation of a narrow viewing angle and low regional illumination, the use of endoscopic assistance in such procedures is being popularized. Neuroendoscopy can aid in the visualization of hidden neurovascular structures and inspection of the parent arterial segment without undue retraction of the lesion. This review focuses on the historical progression of the surgical management of intracranial aneurysms, the technical details of various minimally invasive approaches, patient selection and clinical outcomes of the anterior circulation aneurysms and useful tenets to avoid complications during these procedures. Meticulous preoperative planning to understand the patient's vascular anatomy, the orientation and relationship of the aneurysm to adjacent structures, use of neuronavigation guidance and endoscopic assistance if needed can lead to an optimal surgical outcome while minimizing neurological morbidity and mortality.

Anterior inferior cerebellar artery (AICA) aneurysms are rare lesions with a predisposition for distal location and non-saccular morphology.1,2 These aneurysms are less amenable to clipping and may instead require aneurysm trapping with bypass.3 This video reports a novel bypass for a ruptured, fusiform distal AICA aneurysm. A 51-yr-old woman with newly diagnosed acquired immunodeficiency syndrome presented to the hospital with meningitis and experienced an acute neurological decline while admitted. Neuroimaging revealed a fusiform left a2-AICA aneurysm, thought to be mycotic with diffuse subarachnoid and intraventricular hemorrhage (Hunt-Hess Grade-IV). The occipital artery was harvested as an alternative donor in the myocutaneous flap using a hockey-stick incision. An extended retrosigmoid approach exposed the infectious aneurysm. After aneurysm excision, an a2-AICA-a2-AICA end-to-end reanastomosis was performed in between and deep to the vestibulocochlear nerves superiorly and the glossopharyngeal nerve inferiorly. Indocyanine green videoangiography and postoperative angiogram confirmed bypass patency. Postoperatively, she developed epidural and subdural hematomas due to human immunodeficiency virus-associated coagulopathy and/or increased aspirin sensitivity, requiring reoperation. The patient made a complete recovery at late follow-up. AICA reanastomosis is an elegant intracranial-intracranial bypass for treating distal AICA aneurysms. To our knowledge, this is the first report of AICA reanastomosis in the proximal a2-AICA (lateral pontine) segment. This technique has been reported in the literature for distally located aneurysms (a3-AICA).4 Microanastomosis for more medial AICA aneurysms must be performed deep to the lower cranial nerves. OA to a3-AICA bypass is an alternative in cases where primary reanastomosis is not technically feasible. (Published with permission from Barrow Neurological Institute).

Precise identification of tumor margins is of the utmost importance in neuro-oncology. Confocal microscopy is capable of rapid imaging of fresh tissues at cellular resolution and has been miniaturized into handheld probe-based systems suitable for use in the operating room. We aimed to perform a literature review to provide an update on the current status of confocal laser endomicroscopy (CLE) technology for brain tumor surgery. Aside from benchtop confocal microscopes used in ex vivo fashion, there are four CLE systems that have been investigated for potential application in the workflow of brain tumor surgery. Preclinical studies on animal tumor models and clinical studies on human brain tumors have assessed in vivo and ex vivo imaging approaches, suggesting that confocal microscopy holds promise for rapid identification of the characteristic (diagnostic) histological features of tumor and normal brain tissues. However, there are few studies assessing diagnostic accuracy sufficient to provide a definitive determination of the clinical and economical value of CLE in brain tumor surgery. Intraoperative real-time, high-resolution tissue imaging has significant clinical potential in the field of neuro-oncology. CLE is an emerging imaging technology that shows promise for improving brain tumor surgery workflow in in vivo and ex vivo studies. Future clinical studies are necessary to demonstrate clinical and economic benefit of CLE.

INTRODUCTION Intracerebral hemorrhage (ICH) is associated with a high rate of morbidity and mortality. Minimally-invasive surgery (MIS) has been increasingly used in recent years. We systematically reviewed the role of MIS in the acute management of ICH using various techniques. EVIDENCE ACQUISITION A comprehensive electronic search for relevant articles was conducted on several relevant international databases, including PUBMED (Medline), EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL). EVIDENCE SYNTHESIS Our primary literature research resulted in 1134 articles. In total, 116 publications finally met the eligibility criteria to be included in our systematic review. Five major MIS categories for the evacuation of ICH were identified, respectively: minimally invasive direct aspiration with or without thrombolytics, endoscope assisted technique, sonothrombolysis, aspiration-irrigation device and endoport-assisted evacuation. CONCLUSIONS The role of minimally invasive techniques in the management of ICH remains under dispute. However, a mounting evidence in the literature demonstrates that MIS is associated with significantly improved outcomes when compared with conservative treatment and conventional surgical evacuation strategy.

Autonomic nervous system dysfunction has been previously observed in multiple sclerosis (MS) patients. To assess associations between magnetic resonance imaging-detected neuroinflammatory and neurodegenerative pathology and postural venous flow changes indicative of autonomic nervous system function. We used a standardized 3T magnetic resonance imaging protocol to scan 138 patients with MS and 49 healthy controls. Lesion volume and brain volumes were assessed. The cerebral venous flow (CVF) was examined by color-Doppler sonography in supine and upright positions and the difference was calculated as ΔCVF. Based on ΔCVF, subjects were split into absolute or quartile groups. Student’s t test, χ2-test, and analysis of covariance adjusted for age and sex were used accordingly. Benjamini-Hochberg procedure corrected the p-values for multiple comparisons. No differences were found between healthy controls and patients with MS in both supine and upright Doppler-derived CVF, nor in prevalence of abnormal postural venous control. Patients with absolute negative ΔCVF had higher disability scores (p = 0.013), lower gray matter (p = 0.039) and cortical (p = 0.044) volumes. The negative ΔCVF MS group also showed numerically worse bladder/bowel function when compared to the positive ΔCVF (2.3 vs. 1.5, p = 0.052). Similarly, the lowest quartile ΔCVF MS group had higher T1-lesion volumes (p = 0.033), T2-lesion volumes (p = 0.032), and lower deep gray matter (p = 0.043) and thalamus (p = 0.033) volumes when compared to those with higher ΔCVF quartiles. No difference in postural venous outflow between patients with MS and healthy controls was found. However, when the abnormal ΔCVF is present within the MS population, it may be associated with more inflammatory and neurodegenerative pathology. Further studies should explore whether the orthostatic venous changes are an aging or an MS-related phenomenon and if the etiology is due to impaired autonomic nervous system functioning.

Evidence regarding the role, if any, of dietary and lifestyle factors in the pathogenesis of multiple sclerosis (MS) is poorly understood. To assess the effect of lifestyle-based risk factors linked to cardiovascular disease (CVD) on clinical and MRI-derived MS outcomes. The study enrolled 175 MS or clinically isolated syndrome (CIS) patients and 42 age- and sex-matched healthy controls (HCs) who were longitudinally followed for 5.5 years. The 20-year CVD risk was calculated by Healthy Heart Score (HHS) prediction model which includes age, smoking, body mass index, dietary intake, exercise, and alcohol consumption. Baseline and follow-up MRI scans were obtained and cross-sectional and longitudinal changes of T2-lesion volume (LV), whole brain volume (WBV), white matter volume (WMV), gray matter volume (GMV), and lateral ventricular volume (LVV) were calculated. After correcting for disease duration, the baseline HHS values of the MS group were associated with baseline GMV (rs = − 0.20, p = 0.01), and longitudinal LVV change (rs = 0.19, p = 0.01). The association with LVV remained significant after adjusting for baseline LVV volumes (rs = 0.2, p = 0.008) in MS patients. The diet component of the HHS was associated with the 5-year T2-LV accrual (rs = − 0.191, p = 0.04) in MS. In the HC group, the HHS was associated with LVV (rs = 0.58, p

The relationship between walking disability in multiple sclerosis (MS) patients and their macro- and microstructural MRI-derived measures still remains unclear.To assess the correlations between walking disability and MRI-derived lesion, atrophy, and microstructural/axonal integrity outcomes.Seventy-one (71) MS patients were clinically examined, the expanded timed get-up and go (ETGUG), and timed 25-foot walk (T25FW) tests were assessed. Additionally, the Symbol Digit Modalities Test (SDMT) was obtained. Normalized brain (NBV), gray matter (GMV), white matter (WMV), cortex (CV), and deep GM (DGM) volumes, as well as lesion volumes (LV) and diffusion tensor imaging (DTI) scalar maps of fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity were calculated. Spearman correlation, partial correlation and stepwise regression analyses were performed.T25FW and ETGUG were associated with T2-LV (p .001), global (NBV, p .001), tissue-specific (GMV and CV, p .001) and regional (DGM p .001; and thalamus p .001) volumes. The ETGUG remained correlated with T1-LV, GMV, CV and total DGM volume (all p .001) after age, sex, and disease duration adjustment. The WMV was not associated with walking disability. Similarly, DTI measures did not show significant association with the walking tests. The regression analysis outlined DMG volume as best predictor of T25FW (Adj RDespite the low disability levels, walking as measured by T25FW and ETGUG, is largely explained by the loss of cortical and nuclei specific GM volumes.

BACKGROUND Styloidogenic jugular venous compression syndrome (SJVCS) is a rare cause of idiopathic intracranial hypertension (IIH). OBJECTIVE To elucidate the pathophysiology and the hemodynamics of SJVCS. METHODS We conducted a retrospective review of medical records, clinical images, dynamic venography, and manometry for consecutive patients with SJVCS undergoing microsurgical decompression from April 2009 to October 2017. Patients with IIH with normal venography and manometry findings served as controls. RESULTS Data were analyzed for 10 patients with SJVCS who presented with headaches. Neck flexion exacerbated headaches in 7 patients. Eleven patients with IIH provided control data for normal intracranial venous pressure and styloid process anatomy. Patients with SJVCS had bilateral osseous compression of venous outflow. The styloid processes were significantly longer in patients with SJVCS than in those with IIH (mean [standard deviation (SD)] distance, 31.0 [10.6] vs 19.0 [14.1] mm; P

Objectives: To investigate the factors associated with complementary and alternative medicine (CAM) usage by multiple sclerosis (MS) patients. Design, Setting/Location: Single-center, prospective clinical study at an academic MS center in the northeastern United States. Methods: This study included CAM data from 524 MS patients and 304 healthy controls (HC) enrolled in a prospective study of clinical, neuroimaging, and environmental risk factors in MS at an academic MS Center. Clinical, neuroimaging, and disease-modifying treatment data were obtained. In addition, data on usage of CAM modalities, including acupuncture, aromatherapy, Ayurveda, Chinese herbal medicine, chiropractor, electromagnetic therapy, homeopathy, hypnosis, massage, naturopathy, Qi gong, Reiki, therapeutic touch, and bee stings were collected in an in-person interview. Results: The percentages of HC reporting usage of any CAM (32%) was similar to that in MS patients after diagnosis (30.5%). The usage of any CAM was higher in MS patients after MS diagnosis compared to before MS diagnosis (p

Background and importance Although posterior petrosal approaches are utilized less frequently in many practices today, they continue to provide distinct surgical advantages in carefully selected cases. Here, we report a case of a recurrent cerebellopontine angle (CPA) hemangioblastoma that had failed a prior, more conservative, surgical approach. We provide cadaveric dissections of variations of posterior petrosal approaches to illustrate the advantages of the selected approach. Clinical presentation A 70-yr-old female presented with a growing left CPA hemangioblastoma. The lesion had undergone a prior subtotal resection from a retrosigmoid approach and subsequent adjuvant radiation treatment. The patient had worsening left facial strength, progressive balance difficulty, and absent left auditory function. Preoperative angiogram demonstrated arterial blood supply from the left anterior inferior cerebellar artery (AICA) that was deemed unsafe for embolization due to significant arteriovenous shunting. A posterior petrosal transotic approach was performed in order to optimize the working angle to the anterior brainstem and afford the ability to occlude the vascular supply from AICA prior to surgical resection of the lesion. Conclusion The posterior petrosal transotic approach offers an improved surgical working angle to the anterior brainstem compared to the translabyrinthine approach. This advantage can be particularly important with vascular tumors that receive blood supply anteriorly, as in this case from AICA, and can improve the safety of the resection.

OBJECTIVEExposure of the vertebral artery (VA) between C-1 and C-2 vertebrae (atlantoaxial VA) may be necessary in a variety of pathologies of the craniovertebral junction. Current methods to expose this segment of the VA entail sharp dissection of muscles close to the internal jugular vein and the spinal accessory nerve. The present study assesses the technique of exposing the atlantoaxial VA through a newly defined muscular triangle at the craniovertebral junction.METHODSFive cadaveric heads were prepared for surgical simulation in prone position, turned 30°–45° toward the side of exposure. The atlantoaxial VA was exposed through the subatlantic triangle after reflecting the sternocleidomastoid and splenius capitis muscles inferiorly. The subatlantic triangle was formed by 3 groups of muscles: 1) the levator scapulae and splenius cervicis muscles inferiorly and laterally, 2) the longissimus capitis muscle inferiorly and medially, and 3) the inferior oblique capitis superiorly. The lengths of the VA exposed through the triangle before and after unroofing the C-2 transverse foramen were measured.RESULTSThe subatlantic triangle consistently provided access to the whole length of atlantoaxial VA. The average length of the VA exposed via the subatlantic triangle was 19.5 mm. This average increased to 31.5 mm after the VA was released at the C-2 transverse foramen.CONCLUSIONSThe subatlantic triangle provides a simple and straightforward pathway to expose the atlantoaxial VA. The proposed method may be useful during posterior approaches to the craniovertebral junction should early exposure and control of the atlantoaxial VA become necessary.

Background The greater auricular nerve (GAN) may be used as a nerve graft during neurosurgical procedures to repair damaged nerves. There is extensive literature on localization of the GAN at the posterior triangle of the neck, but objective information on localization of the GAN at the anterior triangle of the neck close to cranial neurosurgical fields is lacking. The aim of this study was to introduce simple and reliable landmarks to localize the GAN at the anterior triangle of the neck to facilitate its harvest during neurosurgical procedures. Methods The GAN was exposed bilaterally in 11 cadaveric specimens at the point of crossing the anterior border of the sternocleidomastoid muscle (anterior greater auricular point [AGA]). Distances from the AGA point to the angle of the mandible and the tip of the mastoid process were measured. Additionally, the location of the crossing point between the GAN and an imaginary line passing through the mastoid tip and the angle of the mandible (M-A line) was found relative to these bony landmarks. Results Mean (±SD) distances from the AGA point to the mastoid tip and the angle of the mandible were 29.1 ± 3.4 mm and 27.5 ± 4.5 mm, respectively. The GAN was always found to cross the M-A line in its middle third (mean 48.2% ± 6.9% from the mastoid tip). Conclusions The AGA point and the M-A line are reliable landmarks for locating the GAN at the anterior triangle of the neck and for helping neurosurgeons expose and harvest the GAN efficiently.

BACKGROUND AND IMPORTANCE Trigeminal neuralgia (TN) secondary to a dolichoectatic basilar artery (DBA) is an extremely rare phenomenon. The Kawase approach for macrovascular decompression of this rare pathology been used rarely. CLINICAL PRESENTATION This report describes macrovascular decompression and basilar artery transposition in a 69-yr-old male presenting with progressively worsening left-sided typical TN secondary to a DBA compression. The DBA was successfully decompressed off of the trigeminal nerve via a pterional craniotomy and anterior petrosectomy. The patient had immediate improvement in TN symptoms postoperatively. The patient remained symptom free with nonbothersome facial numbness in the V3 segment at 8-mo postoperative follow-up in clinic. The patient suffered a sixth nerve palsy following surgery, which was later corrected by strabismus surgery. The natural history and epidemiology of TN, results of macrovascular decompression secondary to DBA compression via a traditional suboccipital retrosigmoid approach, and potential advantages of the Kawase approach are also discussed. CONCLUSION The macrovascular decompression strategy succeeded because the compressive force was applied by the DBA to the nerve in a superolateral direction, and the decompressive sling pulled the DBA away from the nerve in an inferomedial direction. The working space and access to the clival dura through the Kawase approach allowed proper corrective pull with a sling.

Confocal Laser Endomicroscopy (CLE) is novel handheld fluorescence imaging technology that has shown promise for rapid intraoperative diagnosis of brain tumor tissue. Currently CLE is capable of image display only and lacks an automatic system to aid the surgeon in diagnostically analyzing the images. The goal of this project was to develop a computer-aided diagnostic approach for CLE imaging of human glioma with feature localization function. Despite the tremendous progress in object detection and image segmentation methods in recent years, most of such methods require large annotated datasets for training. However, manual annotation of thousands of histopathology images by physicians is costly and time consuming. To overcome this problem, we constructed a Weakly-Supervised Learning (WSL)-based model for feature localization that trains on image-level annotations, and then localizes incidences of a class-of-interest in the test image. We developed a novel convolutional neural network for diagnostic features localization from CLE images by employing a novel multiscale activation map that is laterally inhibited and collaterally integrated. To validate our method, we compared the model output to the manual annotation performed by four neurosurgeons on test images. The model achieved 88% mean accuracy and 86% mean intersection over union on intermediate features and 87% mean accuracy and 88% mean intersection over union on restrictive fine features, while outperforming other state of the art methods tested. This system can improve accuracy and efficiency in characterization of CLE images of glioma tissue during surgery, and may augment intraoperative decision-making regarding the tumor margin and improve brain tumor resection.