Anatomic Feasibility of a Superficial Temporal Artery to Distal Anterior Cerebral Artery Bypass With a Parietal Branch Interposition Graft: The Superficial Temporal Artery Telescope Bypass.

BACKGROUND AND OBJECTIVES: Revascularizing the postcommunicating segment of the anterior cerebral artery (ACA) using extracranial donor sites requires long interposition grafts. The superficial temporal artery (STA) is frequently used for extracranial-intracranial ACA revascularization. However, the length of either STA branch is not sufficient to reach the ACA with a proper caliber match, so an interposition graft is required. The aim of this study was to evaluate a bypass that uses the 2 main branches of the STA to reach the A3 (pericallosal) segment of the ACA. METHODS: The frontal and parietal branches of the STA were dissected from 10 cadaveric specimens. The middle internal frontal artery (MIFA) was exposed through an anterior interhemispheric approach. An interposition graft technique was applied using the parietal branch of the STA (pSTA) to connect the frontal branch of the STA (fSTA) with the MIFA. The bypass code is fSTA (E-Ec) pSTA + pSTA (E-Sc) MIFA. Measurements of length and caliber were taken at the anastomotic sites for the distal branches of the STA and the MIFA. RESULTS: The mean (SD) diameter of the MIFA measured 1.4 (0.2) mm, similar to the calibers of the frontal and parietal branches of the STA. The mean (SD) length of the end-to-side STA-MIFA bypass was 145.5 (7.4) mm, and the mean (SD) length of the donor-graft construct measured 204.2 (27.9) mm. This bypass design resulted in a surplus donor graft length of 38%. CONCLUSION: Using the pSTA as an interposition graft proved to be a successful technique for creating an STA-MIFA bypass, yielding excess donor graft length that facilitated an unstrained bypass construct. This approach offers several advantages, including a single skin incision, ample graft length, caliber compatibility, and a straightforward technical execution.

Relationship between cerebral vasospasm vascular territory and functional outcome after aneurysmal subarachnoid hemorrhage.

BACKGROUND: Vasospasm following aneurysmal subarachnoid hemorrhage (SAH) contributes significant morbidity and mortality after brain aneurysm rupture. However, the association between vascular territory of vasospasm and clinical outcome has not been studied. We present a hypothesis-generating study to determine whether the location of vasospasm within the intracranial circulation is associated with functional outcome after SAH. METHODS: A retrospective analysis of a prospective, intention-to-treat trial for aneurysmal SAH was performed to supplement trial outcomes with in-hospital angiographic imaging and treatment variables regarding vasospasm. The location of vasospasm and the position on the vessel (distal vs proximal) were evaluated. Modified Rankin scale (mRS) outcomes were assessed at discharge and 6 months, and predictive models were constructed. RESULTS: A total of 406 patients were included, 341 with follow-up data at 6 months. At discharge, left-sided vasospasm was associated with poor outcome (odds ratio (OR), 2.37; 95% CI, 1.25 to 4.66; P=0.01). At 6 months, anterior cerebral artery (ACA) vasospasm (OR, 3.87; 95% CI, 1.29 to 11.88; P=0.02) and basilar artery (BA) vasospasm (OR, 6.22; 95% CI, 1.54 to 27.11; P=0.01) were associated with poor outcome after adjustment. A model predicting 6-month mRS score and incorporating vasospasm variables achieved an area under the curve of 0.85 and a net improvement in reclassification of 13.2% (P<0.01) compared with a previously validated predictive model for aneurysmal SAH. CONCLUSIONS: In aneurysmal SAH, left-sided vasospasm is associated with worse discharge functional status. At 6 months, both ACA and BA vasospasm are associated with unfavorable functional status.

In Vivo Preclinical Quantitative Flow Analysis of Arterial Anastomosis Using a Microvascular Anastomotic Coupler and Clinical Application for Extracranial-to-Intracranial Bypass.

OBJECTIVE: Although several commercially available sutureless anastomotic techniques are available, they are not routinely used in neurosurgery. We performed an in vivo flow analysis of end-to-end anastomosis using a microvascular coupler device in rats. We report our first clinical use of the microvascular anastomotic coupler. METHODS: Bilateral rat common carotid arteries (CCAs) were exposed, and a microvascular coupler was used to perform 8 anastomoses. A microflow probe provided quantitative measurement of blood-flow volume. Flow augmentation was assessed with end-to-side anastomoses connecting the distal CCA to the jugular vein (JV). A patient with chronic dominant hemisphere atherosclerotic ischemic disease and progressive symptoms refractory to medical management underwent end-to-end cerebral artery bypass using the microvascular coupler. RESULTS: Mean preanastomosis flow in the rat CCA was 3.95 ± 0.45 mL/min; this flow was maintained at 3.99 ± 0.24 mL/min on final measurements 54-96 minutes postanastomosis. Total occlusion time for each rat CCA was 12-19 minutes. After end-to-side anastomosis, with proximal and distal JV patent, CCA flow increased 477% to 22.8 ± 3.70 mL/min (P = 0.04, proximal; P = 0.01, distal). After in vivo testing, we successfully used the coupler clinically in a superficial temporal artery-to-middle cerebral artery bypass for dominant hemisphere flow augmentation. CONCLUSIONS: In vivo quantitative flow analysis demonstrated no flow difference between an unaltered artery and artery with end-to-end anastomosis using a microvascular coupler in rats. A 1-mm coupled anastomosis achieved a 4-fold flow increase with low-resistance venous outflow in rats, simulating increased arterial demand. The coupler was successfully used for extracranial-to-intracranial bypass in a patient.

The Glossopharyngo-Cochlear Triangle-Part II: Case Series Highlighting the Clinical Application to High-Riding Posterior Inferior Cerebellar Artery Aneurysms Exposed Through the Extended Retrosigmoid Approach.

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 < .01). All 6 aneurysms treated using eRS were completely occluded without operative complications. CONCLUSION: The eRS approach is an important alternative to the FL approach for high-riding PICA aneurysms, identified as having necks more than 23 mm above the foramen magnum on CTA. The glossopharyngo-cochlear triangle is another important anatomic triangle that facilitates microsurgical dissection.

Prognostic value of the Simpson grading scale in modern meningioma surgery: Barrow Neurological Institute experience.

OBJECTIVE: Recently, 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. METHODS: This 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. RESULTS: A 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). CONCLUSIONS: The 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.

Contralateral interoptic approach to paraclinoid aneurysms: a patient-selection algorithm based on anatomical investigation and clinical validation.

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.

Anterior Cerebral Artery Bypass for Complex Aneurysms: Advances in Intracranial-Intracranial Bypass Techniques.

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.

Far Lateral Craniotomy and Occlusion In Situ of a Lateral Medullary Arteriovenous Malformation: 2-Dimensional Operative Video.

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.

Preoperative embolization versus no embolization for WHO grade I intracranial meningioma: a retrospective matched cohort study.

OBJECTIVE: The 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. METHODS: The 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. RESULTS: In 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). CONCLUSIONS: After 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.

An a3-Anterior Inferior Cerebellar Artery to p3-Posterior Inferior Cerebellar Artery Bypass With Thrombectomy and Trapping of an Anterior Inferior Cerebellar Artery Aneurysm: 3-Dimensional Operative Video.

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.

Left Vertebral Artery to Common Carotid Artery Transposition in a Patient With Bilateral Vertebral Insufficiency: 3-Dimensional Operative Video.

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.

An Anatomical Feasibility Study for Revascularization of the Ophthalmic Artery. Part II: Intraorbital Segment.

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.

An Anatomic Feasibility Study for Revascularization of the Ophthalmic Artery, Part I: Intracanalicular Segment.

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.

Lower total cerebral arterial flow contributes to cognitive performance in multiple sclerosis patients.

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 < 0.001 and r = 0.244, q = 0.012 for SDMT and BVMT-R, respectively). Lower GMV, higher T2-LV, and CABF were significantly associated with poorer performance on the processing speed measure of SDMT (adjusted R2 = 0.295, t-statistics = 2.538, standardized ß = 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.

Posterior Inferior Cerebellar Artery (PICA) Reanastomosis After Excision of a Ruptured p2-PICA Aneurysm: 2-Dimensional Operative Video.

Posterior inferior cerebellar artery (PICA) aneurysms have an increased tendency towards a fusiform morphology precluding primary clip reconstruction. The management of these complex aneurysms might require cerebral revascularization to preserve flow in a distal PICA territory. This video illustrates a case of a ruptured p2-PICA aneurysm excision followed by a PICA reanastomosis. A 54-yr-old male presented with a sudden-onset severe headache, diplopia, and complete left cranial nerve six (CN VI) palsy. Neuroimaging demonstrated diffuse subarachnoid hemorrhage in basal cisterns. A catheter angiogram shows a ruptured small fusiform aneurysm in the p2-PICA segment. After obtaining consent for surgery, the patient was placed in a three-quarter prone position. After a hockey stick skin incision and C1 laminectomy, a lateral suboccipital craniotomy was performed. The aneurysm was identified within the vagoaccessory triangle. Cerebral protection consisted of propofol-induced electroencephalography burst suppression during the clamp time for the bypass, without hypothermia or hypertension. After trapping the aneurysm and excising the diseased arterial segment, the distal end of the p2-PICA was reanastomosed to the proximal parent vessel in an end-to-end fashion. Indocyanine green angiography confirmed patency of the anastomosis. Postoperatively, the patient was neurologically at his baseline. The CN VI palsy had completely resolved at a follow-up visit. Reanastomosis is an effective modality for reconstructing PICA following the excision of the fusiform aneurysm. The redundancy of the tonsillomedullary segment of PICA allows for easier distal segment reapproximation in the inferior hypoglossal triangle. An intracranial-intracranial revascularization technique eliminates the need for harvesting the occipital artery. Additionally, it prevents iatrogenic ischemic injury to contralateral PICA, if used for a PICA-PICA bypass.1 © Barrow Neurological Institute, used with permission.

"Reverse Picket Fence" Technique for Clipping of a Large, Anterior Communicating Artery Aneurysm: 2-Dimensional Operative Video.

The "picket fence" technique is a clipping technique used for large, wide-neck complex aneurysms not suitable for conventional clipping.1 With this technique, simple or fenestrated straight clips are stacked side-by-side perpendicular to the neck rather than the conventional parallel placement. In complex aneurysms projecting away from the surgeon, the picket fence technique is impossible. Instead, fenestrated clips are applied in a reverse direction from neck-to-dome, using the blade heels to close the neck. This fenestration tube transmits the bifurcation. This video demonstrates a "reverse picket fence" clipping technique of an incidental, large anterior communicating artery (ACoA) aneurysm in a 52-yr-old woman. Bilaterally adherent A2-anterior cerebral artery (ACA) segments led to abortion of a prior clipping attempt at an outside hospital. After obtaining patient consent, a modified orbitozygomatic craniotomy was performed with gyrus rectus removal. Temporary clips were applied to A1-ACA for freeing the adherent A2-ACA segments from the dome. The aneurysm was clipped using a "reverse picket fence" technique transmitting the A1-A2-A2 bifurcation through the fenestration tube. Bilateral recurrent artery of Heubner was preserved. Indocyanine angiography demonstrated parent vessel patency with complete aneurysm exclusion. Postoperatively, the patient experienced short-term memory loss, which resolved over 6 mo with cognitive rehabilitation. The "reverse picket fence" technique can be considered for large aneurysms directed away from the surgeon, obviating the need for difficult dissection of adherent efferent arteries from aneurysmal sac. Adjusting the heel position of each fenestrated clip in this construct allows the patency of hidden perforators behind the aneurysm to be maintained. Video © Barrow Neurological Institute. Used with permission.

Three-Dimensional Printed Models for Lateral Skull Base Surgical Training: Anatomy and Simulation of the Transtemporal Approaches.

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 <.003, <.007, and <.007, respectively), indicating accurate representation of the surgical corridor and working angles in the 3D-printed models. Participant assessment revealed high face validity, content validity, and construct validity. CONCLUSION: The 3D-printed temporal bone models highlighting key anatomic structures accurately simulated 4 sequential stages of transtemporal approaches with high face validity, content validity, and construct validity. This strategy may provide a useful educational resource for temporal bone anatomy and training in lateral skull base approaches.

Exposure of the V1 Segment of the Vertebral Artery: Stepwise Cadaveric Surgical Simulation.

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.

Excision and Primary Reanastomosis of the Anterior Inferior Cerebellar Artery for Treatment of a Ruptured Mycotic Aneurysm: 2-Dimensional Operative Video.

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).

Applications of Microscope-Integrated Indocyanine Green Videoangiography in Cerebral Revascularization Procedures.

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.