Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Superficial temporal artery to middle cerebral artery (STA-MCA) bypass is the workhorse for flow augmentation surgery. Although either interrupted or running sutures can be used to complete the anastomosis with high intraoperative patency rates, no previous study in the cranial bypass literature has compared long-term patency and maturity of end-to-side STA-MCA anastomoses. We compared STA-MCA anastomoses performed with running vs interrupted sutures by evaluating bypass flow and anastomotic maturation on follow-up vascular imaging. METHODS:Ninety-six STA-MCA anastomoses were performed from 1/2019 to 6/2024. Forty-seven anastomoses (40 patients) with long-term vascular imaging were retrospectively analyzed. All anastomoses were intraoperatively patent on initial revascularization. Patient demographics, clinical course, and imaging were reviewed. All images were reviewed by a neuroradiologist or a cerebrovascular neurosurgeon. RESULTS:Twenty-five anastomoses were performed with interrupted sutures and compared with 22 anastomoses performed with running sutures. All patients underwent a preoperative perfusion assessment confirming a significant hypoperfusion state. There were no significant differences between cohorts in demographics, bypass indication, or time to follow-up. Formal digital subtraction angiography was performed for 35 anastomoses (21 interrupted, 14 running). On digital subtraction angiography follow-up, there was no difference in STA caliber between cohorts (P = .204), but there was a difference in anastomotic growth (P = .014), with 5/21 (23.8%) anastomoses stable or enlarged in the interrupted cohort vs 9/14 (64.3%) stable or enlarged in the running cohort. Notably, of the 47 total anastomoses, there was no difference in long-term bypass patency between interrupted and running anastomoses (22/25 (88.0%) vs 22/22 (100.0%), respectively, P = .380). CONCLUSION/CONCLUSIONS:No significant differences in patency or STA caliber on follow-up imaging were observed between STA-MCA anastomoses performed with interrupted vs running sutures although a difference in anastomotic maturity was observed, with the running suture cohort having a higher proportion of enlarged or stable anastomoses. Further studies are needed for validation.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Robotics are becoming increasingly widespread within various neurosurgical subspecialties, but data pertaining to their feasibility in vascular neurosurgery are limited. We present our novel attempt to evaluate the learning curve of a robotic platform for microvascular anastomoses. METHODS:One hundred and sixty one sutures were performed and assessed. Fourteen anastomoses (10 robotic [MUSA-2 Microsurgical system; Microsure] and 4 hand-sewn) were performed by the senior author on 1.5-mm caliber tubes and recorded with the Kinevo 900 (Zeiss) operative microscope. We separately compared interrupted sutures (from needle insertion until third knot) and running sutures (from needle insertion until loop pull-down). Average suture timing across all groups was compared using an unpaired Student's t test. Exponential smoothing (α = 0.2) was then applied to the robotic data sets for validation and a second set of t tests were performed. RESULTS:We compared 107 robotic sutures with 54 hand-sewn sutures. There was a significant difference between the average time/stitch for the robotic running sutures (n = 55) and the hand-sewn running sutures (n = 31) (31.2 seconds vs 48.3 seconds, respectively; P-value = .00052). Exponential smoothing (α = 0.2) reinforced these results (37.6 seconds vs 48.3 seconds; P-value = .014625). Average robotic running times surpassed hand-sewn by the second anastomosis (38.8 seconds vs 48.3 seconds) and continued to steadily decrease with subsequent stitches. The average of the robotic interrupted sutures (n = 52) was significantly longer than the hand-sewn (n = 23) (171.3 seconds vs 70 seconds; P = .000024). Exponential smoothing (α = 0.2) yielded similar results (196.7 seconds vs 70 seconds; P = .00001). However, average robotic interrupted times significantly decreased from the first to the final anastomosis (286 seconds vs 105.2 seconds; P = .003674). CONCLUSION/CONCLUSIONS:Our results indicate the learning curve for robotic microanastomoses is short and encouraging. The use of robotics warrants further study for potential use in cerebrovascular bypass procedures.

BACKGROUND:Middle meningeal artery embolization (MMAE) has emerged as a promising therapy for chronic subdural hematomas (cSDHs). The efficacy of standalone MMAE compared with MMAE with concurrent surgery is largely unknown. METHODS:cSDH patients who underwent successful MMAE from 14 high volume centers with at least 30 days of follow-up were included. Clinical and radiographic variables were recorded and used to perform propensity score matching (PSM) of patients treated with standalone MMAE or MMAE with concurrent surgery. Multivariable logistic regression models were used for additional covariate adjustments. The primary outcome was recurrence requiring surgical rescue, and the secondary outcome was radiographic failure defined as <50% reduction of cSDH thickness. RESULTS:722 MMAE procedures in 588 cSDH patients were identified. After PSM, 230 MMAE procedures remained (115 in each group). Median age was 73 years, 22.6% of patients were receiving anticoagulation medication, and 47.9% had no preoperative functional disability. Median midline shift was 4 mm and cSDH thickness was 16 mm, representing modestly sized cSDHs. Standalone MMAE and MMAE with surgery resulted in similar rates of surgical rescue (7.8% vs 13.0%, respectively, P=0.28; adjusted OR (aOR 0.73 (95% CI 0.20 to 2.40), P=0.60) and radiographic failure (15.5% vs 13.7%, respectively, P=0.84; aOR 1.08 (95% CI 0.37 to 2.19), P=0.88) with a median follow-up duration of 105 days. These results were similar across subgroup analyses and follow-up durations. CONCLUSIONS:Standalone MMAE led to similar and durable clinical and radiographic outcomes as MMAE combined with surgery in select patients with moderately sized cSDHs and mild clinical disease.

BACKGROUND:Hypoglossal canal dural arteriovenous fistulas (HCDAVFs) are a relatively rare subtype of dural arteriovenous fistula (dAVF), representing 3%-5% of all dAVFs. The complex angio- and venous architecture predisposed to numerous anastomoses and nearby anatomical structures, including the posterior fossa sinuses and cranial nerves, can complicate both the diagnosis and treatment of these lesions. OBSERVATIONS/METHODS:The authors describe the case of HCDAVF in a 74-year-old male who presented with pulsatile tinnitus (PT) lasting 3 months and significant fatigue, headaches, and dizziness. Diagnostic cerebral angiography demonstrated a left-sided HCDAVF with bilateral supply from the ascending pharyngeal arteries and fistulous connection at the level of the left anterior condylar vein (ACV). This lesion was consistent with a Cognard and Borden type I dAVF. LESSONS/CONCLUSIONS:The authors present a case in which transvenous embolization (TVE) with detachable coils via the ipsilateral internal jugular vein successfully occluded the previously visualized shunt to the left ACV and provided a clinical cure for the patient's PT and headaches without complication. Selecting the appropriate treatment strategy for the successful treatment of HCDAVFs is predicated on a comprehensive understanding of the anatomical features of the lesion, namely arterial feeders, venous drainage pattern, and location of the fistulous connection. TVE is a safe and efficacious treatment option for HCDAVFs. https://thejns.org/doi/10.3171/CASE24606.

The anatomy of vertebrobasilar perforators has been widely studied in human cadavers, with most reports found in the neurosurgical literature. These arterial perforators are extremely hard to visualize consistently with traditional two-dimensional digital subtraction angiography, but are reliably visible with cross sectional cone beam CT techniques. A clear understanding of this specific neurovascular anatomy and pathology is essential for informed treatment decisions. This review analyzes the anatomy of vertebrobasilar perforators with a focus on practical implications for aneurysm treatment, particularly flow diversion.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Multiple preferences exist for embolic materials selection in middle meningeal artery embolization (MMAE) for chronic subdural hematoma with limited comparative literature data. Herein, we compare different embolic materials. METHODS:Consecutive patients undergoing MMAE for chronic subdural hematoma at 14 North-American centers (2018-2023) were classified into 3 groups: (a) particles, (b) Onyx, (c) n-butyl cyanoacrylate (n-BCA). The end points were unplanned rescue surgery, radiographic success (≥50% reduction in hematoma thickness at last imaging "minimum of 2 weeks"), and major complications. Initial unmatched analysis compared the 3 groups; subsequent propensity score matching (PSM) compared particles vs liquid embolics (groups b and c combined). Additional subgroup PSM analyses compared particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA. All matched analyses controlled for age, sex, concurrent surgery, previous surgery, hematoma thickness, midline shift, pretreatment antithrombotics, and baseline modified Rankin Scale. RESULTS:Eight hundred and seventy-two patients (median age 73 years, 72.9% males) underwent 1070 MMAE procedures. Onyx was most used (41.4%), then particles (40.3%) and n-BCA (15.5%). Surgical rescue rates were comparable between particles, Onyx, and n-BCA (9.8% vs 7% vs 11.7%, respectively, P = .14). Similarly, radiographic success (78.8% vs 79.3% vs 77.4%; P = .91) and major complications (2.4% vs 2.3% vs 2.5%; P = .83) were comparable. The PSM comparing particles vs liquid generated 128 matched pairs; general anesthesia and bilateral procedures were significantly higher in particles (37.8% vs 21.3%; P = .004 and 39.8% vs 27.3%; P = .034, respectively). No differences in surgical rescue, radiographic improvement, or major complications were noted (P > .05). Concurrently, PSM comparing particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA, resulted in 112, 42, and 40 matched pairs, respectively, without differences in surgical rescue, radiographic success, or major complications (P > .05). CONCLUSION/CONCLUSIONS:We found no differences in radiological improvement, surgical rescue, or major complications between embolic materials in MMAE. Current randomized trials are exclusively using liquid embolics, and these data suggest that future trials involving particles are likely to produce similar outcomes.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Iatrogenic cerebrovascular injury can cause intracranial hemorrhage and pseudoaneurysm formation, putting patients at high risk for postoperative bleeding. No consensus for management exists. This study describes endovascular treatment of these acute injuries with flow diverter stents. METHODS:Electronic medical records were retrospectively reviewed for injury type and etiology, timing of diagnosis, and endovascular management, including antiplatelet regimens, embolization results, and clinical outcome. RESULTS:Six patients were included. Three suffered an injury to the internal carotid artery, 1 suffered an injury to the left anterior cerebral artery, 1 suffered an injury to the right posterior cerebral artery, and 1 suffered an injury to the basilar artery. Four of the 6 injuries occurred during attempted tumor resection, 1 occurred during cerebrospinal fluid leak repair, and 1 occurred during an ophthalmic artery aneurysm clipping. All injuries resulted in pseudoaneurysm formation. Four were immediately detected on angiography; 2 were initially negative on imaging. Five were treated with a pipeline embolization device, and 1 was treated with a Silk Vista Baby. Two were treated with 2 pipeline embolization devices telescopically overlapped across the pseudoaneurysm. All devices deployed successfully. No pseudoaneurysm recurrence or rebleeding occurred. No parent artery occlusion or stenosis was observed, and complete pseudoaneurysm occlusion was observed in 4 patients (in 2 patients, follow-up imaging could not be obtained). CONCLUSION/CONCLUSIONS:With proper antiplatelet regimens, flow diverter stents can be used safely to successfully treat complex acute iatrogenic injuries. Early repeat angiogram is needed when immediate postinjury imaging does not discover the point of vessel injury.

Dural arteriovenous fistulas (dAVFs) can occur as complications after surgical procedures, especially following the resection of meningiomas near the dural sinus. This case report presents a 74-year-old male who developed a recurrent sigmoid dAVF following meningioma resection. Initially treated with transvenous embolization and middle meningeal artery embolization, the dAVF recurred with worsening clinical symptoms. Conventional treatment options, including sinus sacrifice and transarterial embolization, were unsuitable due to the critical role of the patient's dominant right sigmoid sinus in cerebral venous drainage. Consequently, a reconstructive approach was employed using a pipeline embolization device (PED) construct. The PED successfully occluded the dAVF while preserving the function of the sigmoid sinus. A follow-up angiogram confirmed stable occlusion and normalization of intracranial venous drainage. This case underscores the potential of flow diversion as a viable treatment option for dAVFs, particularly in scenarios where preserving venous sinus function is paramount.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Inherent complex angioarchitecture associated with ethmoidal dural arteriovenous fistulas (dAVFs) can make endovascular treatment methods challenging. Many surgical approaches are accompanied by unfavorable cosmetic results such as facial scarring. Blepharoplasty incision of the eyelid offers a minimal, well-hidden scar compared with other incision sites while offering the surgeon optimal visualization of pathogenic structures. This case series aims to report an initial assessment of the safety and efficacy of supraorbital craniotomy by blepharoplasty transpalpebral (eyelid) incision for surgical disconnection of ethmoidal dAVFs. METHODS:Retrospective chart review was conducted for all patients who underwent blepharoplasty incision and craniotomy for disconnection of ethmoidal dAVFs at our institution between October 2011 and February 2023. Patient charts and follow-up imaging were reviewed to report clinical and angiographic outcomes as well as periprocedural and follow-up complications. RESULTS:Complete obliteration and disconnection of ethmoidal dAVF was achieved in all 6 (100%) patients as confirmed by intraoperative angiogram with no resulting morbidity or mortality. Periprocedural complications included one case of transient nasal cerebrospinal fluid leak that was self-limiting and resolved before discharge without intervention. CONCLUSION/CONCLUSIONS:Surgical treatment for ethmoidal dAVFs, specifically by transpalpebral incision and supraorbital craniotomy, is a safe and effective treatment option and affords the surgeon greater access to the floor of the anterior fossa when necessary. In addition, blepharoplasty incision addressed patient concerns for facial scarring compared with other incision sites by creating a more well-hidden, minimal scar in the natural folds of the eyelid for patients with an eyelid crease.

OBJECTIVE:The objective of this study was to investigate the use of indocyanine green videoangiography with FLOW 800 hemodynamic parameters intraoperatively during superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery to predict patency prior to anastomosis performance. METHODS:A retrospective and exploratory data analysis was conducted using FLOW 800 software prior to anastomosis to assess four regions of interest (ROIs; proximal and distal recipients and adjacent and remote gyri) for four hemodynamic parameters (speed, delay, rise time, and time to peak). Medical records were used to classify patients into flow and no-flow groups based on immediate or perioperative anastomosis patency. Hemodynamic parameters were compared using univariate and multivariate analyses. Principal component analysis was used to identify high risk of no flow (HRnf) and low risk of no flow (LRnf) groups, correlated with prospective angiographic follow-ups. Machine learning models were fitted to predict patency using FLOW 800 features, and the a posteriori effect of complication risk of those features was computed. RESULTS:A total of 39 cases underwent STA-MCA bypass surgery with complete FLOW 800 data collection. Thirty-five cases demonstrated flow after anastomosis revascularization and were compared with 4 cases with no flow after revascularization. Proximal and distal recipient speeds were significantly different between the no-flow and flow groups (proximal: 238.3 ± 120.8 and 138.5 ± 93.6, respectively [p < 0.001]; distal: 241.0 ± 117.0 and 142.1 ± 103.8, respectively [p < 0.05]). Based on principal component analysis, the HRnf group (n = 10) was characterized by high-flow speed (> 75th percentile) in all ROIs, whereas the LRnf group (n = 10) had contrasting patterns. In prospective long-term follow-up, 6 of 9 cases in the HRnf group, including the original no-flow cases, had no or low flow, whereas 8 of 8 cases in the LRnf group maintained robust flow. Machine learning models predicted patency failure with a mean F1 score of 0.930 and consistently relied on proximal recipient speed as the most important feature. Computation of posterior likelihood showed a 95.29% chance of patients having long-term patency given a lower proximal speed. CONCLUSIONS:These results suggest that a high proximal speed measured in the recipient vessel prior to anastomosis can elevate the risk of perioperative no flow and long-term reduction of flow. With an increased dataset size, continued FLOW 800-based ROI metric analysis could be used to guide intraoperative anastomosis site selection prior to anastomosis and predict patency outcome.