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Introduction: Delayed intraparenchymal hemorrhage is a known complication of the Pipeline Embolization device (PED); however, its etiology is unclear and some have suggested it is a flow related phenomenon. Quantitative magnetic resonance angiography (QMRA) serves as a powerful tool to collect and analyze hemodynamic data. We report a detailed characterization of short-term hemodynamics after PED placement. Methods: Patients who underwent PED placement for a distal internal carotid artery (ICA) aneurysm between 2017 to 2019 with post embolization QMRA were reviewed. Aneurysm characteristics, flow volume rate (ml/min), mean, systolic, and diastolic flow velocities (cm/s), vessel diameter (mm), pulsatility index, Lindegaard ratio, and wall shear stress (WSS) were collected. Results: A total of 67 patients were included. Post-procedure patients were found to have a significantly lower ICA flow on the side with flow diversion when compared to the side without flow diversion (218 vs. 236.3; P < 0.05). Average ICA flow after flow diversion for aneurysms >2 cm was significantly lower when compared to the untreated side (187.7 vs. 240.4; P < 0.05). There was no difference in MCA or ACA flow or velocity. WSS was significantly lower in the treated ICA (8.2 vs. 9.0; P < 0.05). Lindegaard ratio was not different in the treated vs. contralateral untreated sides. Conclusion: PED placement for distal ICA aneurysms results in lower flow, mean velocity, and WSS when compared to the contralateral untreated ICA. This is not demonstrated distal to the Pipeline device in the ACA or MCA territories. Ultimately these findings suggest hemodynamic changes are not a cause of PED complications. [ABSTRACT FROM AUTHOR]

Extracranial–intracranial (EC/IC) bypass is a useful procedure for the treatment of cerebral vascular insufficiency or complex aneurysms. We explored the role of multidetector computed tomography angiography (MDCTA), instead of digital subtraction angiography (DSA), for the postoperative assessment of EC/IC bypass patency. We retrospectively analyzed a consecutive series of 21 MDCTAs from 17 patients that underwent 25 direct or indirect EC/IC bypass procedures between April 2003 and November 2007. Conventional DSA was available for comparison in 13 cases. MDCTA used a 64-slice MDCT scanner (Aquilion 64, Toshiba). The proximal and distal patencies were analyzed independently on MDCTA and DSA by a neuroradiologist and a neurosurgeon. The bypass was considered patent when the entire donor vessel was opacified without discontinuity from proximal to distal ends and was visibly in contact with the recipient vessel. MDCTA depicted the patency status in every patient. Bypasses were patent in 22 cases, stenosed in one, and occluded in two. DSA always confirmed the results of the MDCTA (sensitivity = 100%, 95% CI = 0.655–1.0; specificity 100%, 95% CI = 0.05–1.0). MDCTA is a non-invasive and accurate exam to assess the postoperative EC/IC bypass patency and is a promising technique in routine follow-up. [ABSTRACT FROM AUTHOR]

Background: Posterior fossa dural arteriovenous fistulas (dAVFs) are rare vascular lesions with variable risk of hemorrhage, mostly depending on the pattern of the venous drainage. While endovascular embolization is the mainstay treatment for most dAVFs, some posterior fossa lesions require a multidisciplinary approach including surgery. The goal of our study was to examine the outcome of an interdisciplinary treatment for posterior fossa dAVFs. Methods: A retrospective review of patients treated for posterior fossa dAVFs was conducted. Results: A total of 28 patients with a mean age of 57.8 years were included. Patients presented with a Cognard grade I in 2 (7%), II a in 5 (18 %), II b in 7 (25%), II a + b in 5 (18%), III in 3 (11%), and IV in 6 (21%) cases. Hemorrhage was the initial presentation in 2 (22%) patients with Cognard grade IV, in 3 with Cognard grade III (33%), in 1 (11%) with Cognard II a + b, and 3 (33%) with Cognard II b. A complete angiographic cure was achieved in 24 (86%) patients—after a single-session embolization in 16 (57%) patients, multiple embolization sessions in 2 (7%), a multimodal treatment with embolization and surgical disconnection in 3 (11%), and with an upfront surgery in 3 (11%). Complete long-term obliteration was demonstrated in 18/22 (82%) at the mean follow-up of 17 months. Fistulas were converted into asymptomatic Cognard I lesion in 4 (14%) patients. Conclusion: Posterior fossa dAVFs represent a challenging vascular pathology; however, despite their complexity, an interdisciplinary treatment can achieve high rates of angiographic and symptomatic cure with low morbidity and mortality rates. Long-term surveillance is warranted as late recurrences may occur. [ABSTRACT FROM AUTHOR]

Introduction: Accurate sizing of the Woven EndoBridge (WEB) device is of critical importance as it determines procedural safety and successful occlusion of wide neck bifurcation aneurysms. The aim of this study was to assess the ability of aneurysm volume to assist in accurate WEB size selection. Methods: All patients with an intracranial aneurysm treated with the WEB SL or WEB SLS device between March 2019 and October 2019 were identified for this retrospective study. Aneurysm volumes were calculated with auto-segmentation using a three-dimensional volume rendering program on an independent Syngo workstation (Siemens Healthineers AG). Pearson correlation coefficients were calculated for aneurysm auto-segmented volumes and WEB volumes, as well as for aneurysm height × width and WEB height × width. Follow-up angiographic outcomes were collected at 6–9 months post-procedure. Results: Twenty-nine aneurysms were evaluated by 3D rotational angiography. The correlation coefficient with WEB size was larger for auto-segmented aneurysm volumes (r = 0.979) compared to height × width measurements (r = 0.867). Using Fisher r-to-z transformations, we found the difference between the two correlations to be statistically significant (p = 0.0007). Follow-up angiography available in 13 subjects demonstrated an 85% complete aneurysm occlusion rate. Conclusion: Aneurysm volumes are highly correlated with WEB volumes, with auto-segmentation volumes displaying statistically significant difference against conventional height by width measurements. These results suggest that volumetric measurements of aneurysm size provide a useful adjuvant measure to assist in appropriate size selection of the WEB device. [ABSTRACT FROM AUTHOR]

An editorial is presented on the evaluation of the hearing preservation (HP) for the vestibular schwannomas (VS) and using auditory brainstem response (ABR) techniques. It expresses the possible failure of the stereotactic radiosurgery (SRS) for tumour burden and instead the use of HP for VS monitoring.

Resection of deep medial frontal and parietal arteriovenous malformations (AVMs) is often challenging due to a tangential angle of attack and deep, narrow working corridor. Adequate visualization of the AVM and its feeding arteries without brain retraction is of particular importance when operating in or near eloquent cortical areas, where brain manipulation could inadvertently result in neurologic deficits. The aim of this paper is to provide a step-by-step description of surgical approach and report our experience with the contralateral transfalcine approach for resection of deep-seated parasagittal AVMs. Contralateral transfalcine resection of deep frontal, parietal, and cingulate gyrus AVMs was performed with the unaffected hemisphere positioned in a gravity-dependent manner in 5 cases. Surgical procedures were video documented, and an illustrative case is presented. All 5 patients had a modified Rankin Scale score of 0 or 1 at the last follow-up. Complete resection of the AVM was achieved in all 5 cases. No permanent major neurologic deficit was observed postoperatively. This approach allowed a superior visualization of arterial feeders, the parenchymal side of the AVM, and an early control of small parenchymal feeders while minimizing retraction of the brain. The contralateral transfalcine approach is a useful technique in the cerebrovascular surgeon's armamentarium for management of deep-seated medial frontal, parietal, and cingulate gyrus AVMs in or around eloquent brain areas, allowing to minimize normal brain retraction and avoid associated neurologic deficits. [ABSTRACT FROM AUTHOR]

Background: Giant and large pituitary adenomas (PA) constitute a specific subset of PAs, with gross total resection (GTR) rates frequently not exceeding 50%. Both an anatomical inaccessibility and an inadequate tumor visualization are thought to play a role. This study analyzes risk factors for postoperative residuals after endoscopic transsphenoidal pituitary surgery for large and giant pituitary adenomas. Methods: A retrospective analysis of patients with giant and large PA operated between 2015 and 2018 was performed. Results: Forty patients (13 females, 27 males) were included in the analysis (30 large and 10 giant PAs). The mean MRI follow-up time was 5.9 ± 6.54 months. Overall, GTR was achieved in 29 patients (72.5%), subtotal resection in 9 (22.5%), and the inconclusive result was in 2 (5%). Unexpected residuals represented 7 (77.7%) of all 9 residual tumors. The most frequent intraoperative factor associated with unexpected residual tumors was improper identification of residual tumor due to obstruction of view in 2 (28.5%) cases and inability to distinguish normal tissue from tumor in the other two (28.5%). Sub-analysis based on tumor size revealed that with large PAs, GTR was achieved in 25 (83.3%), STR in 4 (13.3%), and inconclusive in 1 (3.3%) patient. In patients with giant PAs, GTR was achieved in 4 (40%), STR in 5 (50%), and inconclusive in 1 (10%). Analysis of preoperative factors showed a significant association of residual tumors with larger suprasellar AP distance (p = 0.041), retrosellar extension (p = 0.007), and higher Zurich Score (p = 0.029). Conclusion: Large and giant PAs are challenging lesions with high subtotal resection rates. Suprasellar AP distance, retrosellar extension, and higher Zurich Score seem to be significant predictors of degree of resection in these tumors. Improving the intraoperative ability to distinguish tumor from a normal tissue might further decrease the number of unexpected residuals. [ABSTRACT FROM AUTHOR]

Craniopharyngiomas (CPs) are rare, benign tumors derived from Rathke's pouch, known for their high recurrence rates and associated morbidity and mortality. Despite significant investigation on risk factors for recurrence, a lack of consensus persists. Recent research suggests that specific histopathological and molecular characteristics are prognostic for disease progression. In this systematic review, we analyzed and consolidated key features of CPs that contribute to increased recurrence rates. This systematic review was performed in accordance with PRISMA guidelines. A search string was created with the keywords "craniopharyngioma," "histology," "histopathology," "molecular," and "recurrence." Literature was collected from 2006 to 2016 on the PubMed/Medline and Web of Science databases. The initial search resulted in 242 papers, examined with inclusion and exclusion criteria. The final review included a total of 37 studies, 36 primary studies covering a total of 1461 patients and 1 previous meta-analysis. Cystic lesions and whorl-like arrays were found to be associated with increased recurrence, while previously considered reactive gliosis and finger-shaped protrusions were not. The genetic elements found to be associated with increased risk of recurrence were Ki-67, Ep-CAM, PTTG-1, survivin, and certain RAR isotypes, as well as the glycoproteins osteonectin and chemokines CXCL12/CXCR4. The effects of VEGF, HIF-1α, and p53, despite extensive study, yielded conflicting results. Certain histopathological and molecular characteristics of CPs provide insight into their pathogenesis, likelihood of recurrence, and potential novel targets for therapy. [ABSTRACT FROM AUTHOR]

Endoscopic transsphenoidal surgery (ETSS) for prolactinoma is reserved for dopamine agonist (DA) resistance, intolerance, or apoplexy. High remission (overall 67%, microprolactinoma up to 90%), low recurrence (5–20%) rates highlighted that surgery might be first-line treatment. To report on outcomes of ETSS in a cohort of prolactinomas. Multicenter retrospective cohort of 137 prolactinoma patients (age 38.2 ± 13.7 years; 61.3% female, median follow-up 28.0 [15.0–55.5] months) operated between 2010–2019 with histopathological confirmation. Median preoperative prolactin levels were 166 (98–837 µg/L; males 996 [159–2145 µg/L] vs. females 129 [84–223 µg/L], p <0.001). 56 (40.9%) microprolactinomas, 69 (50.4%) macroprolactinomas, and 7 (5.1%) giant prolactinomas were included, whereas no adenoma was detected in 5 (3.6%) patients. Males had larger tumors (macroprolactinomas: 38, 71.7%) vs. 31 (36.9%), p <0.001; giant prolactinomas: 7 (13.2%) vs. 0 (0.0%), (p <0.001). Prolactinomas were graded as KNOSP-3 in 15 (11.5%), and KNOSP-4 in 20 (15.3%) patients. Primary indication was DA intolerance (59, 43.1%); males 14 (26.4%) vs. females 45 (53.6%), p = 0.006. Long-term remission (i.e., DA-free prolactin level <1xULN) was achieved in 87 (63.5%) patients, being higher in intended complete resection (69/92 [75.0%]), and lower in males (25 [47.2%] vs. 62 females [73.8%], p = 0.002). Transient DI (n = 29, 21.2%) was the most frequent complication. Despite high proportions of macroprolactinoma and KNOSP 3–4, long-term remission rates were 63.5% overall, and 83.3% in microprolactinoma patients. Males had less favorable remission rate compared to females. These findings highlight that ETSS may be a safe and efficacious treatment to manage prolactinoma. [ABSTRACT FROM AUTHOR]

Background: Currently, there is no consensus in the initial management of small vestibular schwannomas (VSs). They are routinely watched and/or referred for radiosurgical treatment, although surgical removal is also an option. We hereby evaluate clinical outcomes of patients who have undergone surgical removal of smaller symptomatic VSs.Methods: Patients with vestibular schwannomas (grade T1-T3b according to Hannover classification) were reviewed. Patients with symptomatic tumors who underwent surgery were evaluated. Their preoperative hearing status was based on the guideline of the committee on hearing and equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) foundation. Their postoperative facial nerve function, hearing status, vestibular symptoms, and degree of tumor resection were assessed.Results: Thirty patients were selected for surgery via a retrosigmoid approach based on their age, symptoms, and their own decision-making after discussion of management options. Most patients presented with hearing loss. Seventeen patients had useful hearing preoperatively. Among them, 10 patients (59%) preserved useful hearing (class A or B) postoperatively. MRI at 1-year follow-up confirmed complete resection in 26/29 patients. Also, 29 patients (97%) had HB grade I-II, and 1 patient had HB III at 1-year follow-up. Except for 1 patient with CSF leak, 1 patient with delayed facial nerve palsy, and 2 patients with asymptomatic sigmoid sinus occlusion, there were no other new morbidities.Conclusion: Although both observation and radiosurgery are valid options in the management of smaller size vestibular schwannomas, surgical treatment seems to offer a high rate of facial nerve preservation, a reasonable rate of hearing sparing, and a high total resection rate. Clinicians should consider surgical treatment as a valid option in the initial management of symptomatic small vestibular schwannomas in younger patients. [ABSTRACT FROM AUTHOR]

Endovascular coiling of small, intracranial aneurysms remains controversial and difficult, despite advances in technology.We retrospectively reviewed data for 62 small aneurysms (<3.99 mm) in 59 patients. Occlusion rates, complications rates, and coil packing densities were compared between subgroups based upon coil type and rupture status.Ruptured aneurysms predominated (67.7%). Aneurysms measured 2.99 ± 0.63 mm by 2.51 ± 0.61 mm with an aspect ratio of 1.21 ± 0.34 mm. Brands included Optima (Balt) (29%), MicroVention Hydrogel (24.2%), and Penumbra SMART (19.4%) coil systems. Average packing density was 34.3 ± 13.5 mm3. Occlusion rate was 100% in unruptured aneurysms; 84% utilized adjuvant devices. For ruptured aneurysms, complete occlusion or stable neck remnant was achieved in 88.6% while recanalization occurred in 11.4%. No rebleeding occurred. Average packing density (p = 0.919) and coil type (p = 0.056) did not impact occlusion. Aspect ratio was smaller in aneurysms with technical complications (p = 0.281), and aneurysm volume was significantly smaller in those with coil protrusion (p = 0.018). Complication rates did not differ between ruptured and unruptured aneurysms (22.6 vs. 15.8%, p = 0.308) or coil types (p = 0.830).Despite advances in embolization devices, coiling of small intracranial aneurysms is still scrutinized. High occlusion rates are achievable, especially in unruptured aneurysms, with coil type and packing density suggesting association with complete occlusion. Technical complications may be influenced by aneurysm geometry. Advances in endovascular technologies have revolutionized small aneurysm treatment, with this series demonstrating excellent aneurysm occlusion especially in unruptured aneurysms. [ABSTRACT FROM AUTHOR]

Brain arteriovenous malformations (BAVMs) are frequently managed by endovascular embolization with a growing number of centers embolizing with intent to cure. Hemorrhage post-embolization is a severe and poorly understood complication. We present a novel imaging finding associated with post-embolization hemorrhage that has significantly impacted the management of patients at our institution.A retrospective review of all patients undergoing embolization of BAVM at a single center was performed. Post-embolization magnetic resonance imaging (MRI) was reviewed for the presence of T2 fluid-attenuated inversion recovery (FLAIR) hyperintense vessels (FHVs). Bivariate analysis was performed to determine associations between patient characteristics and risk of hemorrhage.A total of 50 patients underwent 75 embolization procedures. Forty-six post-embolization MRIs were available for review. There were four hemorrhages and 100% of those presented with FHV. In contrast, only 11.9% of embolization procedures without post-procedural hemorrhage had FHVs on MRI. In total, 18.7% of embolizations led to some morbidity or mortality, with only 6.7% leading to permanent morbidity or mortality. In bivariate analysis, only the presence of FHVs was correlated with the risk of hemorrhage (p < 0.05).This is the first series to describe the finding of hyperintense blood vessels on FLAIR imaging after embolization of BAVMs and correlate it with hemorrhage post embolization. This finding can help guide practitioners and potentially identify patients at risk of delayed hemorrhage post embolization. [ABSTRACT FROM AUTHOR]

Background Diffusion tensor imaging (DTI) estimates the course and connectivity patterns of white matter tracts. The objective of this study is to evaluate whether findings in the brain stem modify the preoperative surgical trajectory planning or postoperative outcome in patients with brain stem cavernous malformations. Methods Ten patients with symptomatic brainstem cavernous malformation underwent surgical resection. Five patients received preoperative DTI evaluation and the remaining 5 did not. Reconstructed DTI tracts consisted of corticospinal, medial lemnisci, and cerebellar peduncles. The surgical planning and postoperative outcome were evaluated. Results In 5 patients with no preoperative DTI evaluation, surgical planning was based on anatomic landmark and the 2-point technique. The other 5 patients underwent preoperative DTI, and findings were factored into the selection of the surgical approach. In 3 of the 5 cases with DTI evaluation, the 2-point technique suggested a similar trajectory. In the other 2, the DTI findings suggested a different approach to avoid damage to the white matter tract. Two patients in the group with no DTI had immediate postoperative new or worsened deficit, which improved at long-term follow-up. No patient in the DTI group had a new neurologic deficit. Conclusions Compared with the standard magnetic resonance imaging, DTI provided improved visualization of cavernous malformation involvement in eloquent fiber tracts of the brainstem. This additional information might help in selecting a more appropriate surgical trajectory in selected lesions. Larger patient cohorts are needed to assess the effect of this modality in patients’ outcome. [ABSTRACT FROM AUTHOR]

Objective Awake craniotomy for removal of intra-axial lesions is a well-established procedure. Few studies, however, have investigated the usefulness of this approach for resection of arteriovenous malformations adjacent to eloquent language areas. We demonstrate our experience by using cortical stimulation mapping and report for the first time on the usefulness of subcortical stimulation with interrogation of language function during resection of arteriovenous malformations (AVMs) located near language zones. Methods Patients undergoing awake craniotomy for AVMs located in language zones and at least 5 mm away from the closest functional magnetic resonance imaging activation were analyzed. During surgery, cortical bipolar stimulation at 50 Hz, with an intensity of 2 mA, increased to a maximum of 10 mA was performed in the region around the AVM before claiming it negative for language function. In positive language site, the area was restimulated 3 times to confirm the functional deficit. The AVM resection was started based on cortical mapping findings. Further subcortical stimulation performed in concert with speech interrogation by the neuropsychologist continued at key points throughout the resection as feasible. The usefulness of cortical and subcortical stimulation in addition to patient outcomes was analyzed. Results Between March 2009 and September 2014, 42 brain AVM resections were performed. Four patients with left-sided language zone AVMs underwent awake craniotomy. The AVM locations were fronto-opercular in 2 patients and posterior temporal in 2. The AVM Spetzler-Martin grades were II (2 patients) and III (2 patients). In 1 patient, complete speech arrest was noticed during mapping of the peri-malformation zone, which was not breached during resection. In a second patient who initially demonstrated negative cortical mapping, a speech deficit was noticed during resection and subcortical stimulation. This guided the approach to protect and avoid the sensitive zone. This patient experienced mild postoperative expressive dysphasia that improved to normal within 6 weeks. Complete resection was achieved in all 4 patients. There were no other complications and no permanent neurological morbidity, resulting in good outcome in all 4 patients. Conclusions Language mapping, both cortical and subcortical during AVM resection, may be valuable in a very select group of AVMs in language zones. Defining safe margins and feedback to the surgeon may provide the highest chances of a surgical cure while minimizing the risk of incurring a language deficit. [ABSTRACT FROM AUTHOR]

Background The endoscopic endonasal approach for pituitary neoplasms has shown similar efficacy compared with the microscopic approach. However, outcomes and complication rates with larger macroadenomas is not as well documented. This study addresses the efficacy and outcome of the fully endoscopic endonasal approach for large and giant pituitary adenomas. Methods Endoscopic endonasal resection was performed in 39 patients with large (>3 cm) or giant (>4 cm) pituitary macroadenomas. Outcomes were assessed using formal visual examinations, endocrine status, and neurologic examinations. Statistical analyses of multiple variables were addressed for correlation to visual, endocrine, and neurologic outcomes. Results Gross total resection of the pituitary macroadenoma was achieved in 22 of 39 (56.4%) patients based on postoperative magnetic resonance imaging. Higher Knosp grade was associated with near-total resection or subtotal resection ( P = 0.0004). All patients had improved or stable visual symptoms. Time to diagnosis, preoperative visual deficit, and tumor size were not significant predictors of visual outcome. Of patients, 34 (87.1%) had a “good” endocrine outcome, whereas 5 did not. Among the 5 patients who did not have a good outcome, 1 had new hypopituitarism, and 4 required increased dosages of pharmacologic therapy. All patients with recurrent tumors had stable visual and good endocrine outcomes. Postoperative cerebrospinal fluid leak occurred in 4 patients; lumbar drainage resolved the leak in 3, and reoperation was performed in 1 patient. There were no new cranial nerve deficits, new neurologic deficits, or mortality. Conclusions Endoscopic endonasal resection of large and giant pituitary macroadenomas is safe and efficient. Postoperative complications, including cerebrospinal fluid leak, are low. Surgical efficacy of the fully endoscopic endonasal approach for large and giant macroadenomas makes the technique a preferable option in this subset of patients. [ABSTRACT FROM AUTHOR]

A 79-year-old woman presented to the emergency department following multiple falls in the previous week. Her past medical history was unremarkable except for chronic obstructive pulmonary disease. She was neurologically intact on arrival with normal laboratory data. Brain imaging revealed a right-sided sphenoid wing meningioma with considerable edema around it. Owing to her cognitive decline and recent symptoms, it was decided to proceed with surgical resection of the lesion. Considering her age and underlying disease, we planned to avoid probable complications of an aggressive resection. She underwent preoperative transarterial embolization with particles. In the supine position, a right pterional craniotomy with orbital extension was performed followed by tumor resection under microscopic magnification. One of the branches of the middle cerebral artery was engulfed by the tumor and could not be separated; therefore, the artery was cut to resect the tumor and then mobilized and reanastomosed under microscope. Doppler probe confirmed patency of the anastomosis. The patient recovered well from the surgery, experienced an uneventful hospital stay, and was discharged on postoperative day 10 after completely controlling her chronic obstructive pulmonary disease. Postoperative imaging did not show any signs of infarction, and the revascularized artery was patent on postoperative computed tomography angiography (Video 1). [ABSTRACT FROM AUTHOR]

Background : The endovascular treatment of complex intracranial aneurysms, such as wide-neck aneurysms (WNAs), remains a challenge. More established endovascular techniques, which include balloon-assisted coiling, stent-assisted coiling, and flow diversion, all have their drawbacks. Intrasaccular flow disruptor devices have emerged as a useful tool for the neurointerventionalist. Methods : Here, we discuss landmark studies and provide a comprehensive, narrative review of the Woven EndoBridge (WEB; Microvention, Alisa Viejo, CA, USA), Artisse (Medtronic, Irvine, CA, USA), Contour (Stryker, Kalamazoo, MI, USA), Saccular Endovascular Aneurysm Lattice Embolization System (SEAL; Galaxy Therapeutics Inc, Milpitas, CA, USA), Medina (Medtronic, Irvine, CA, USA), and Trenza (Stryker, Kalamazoo, MI, USA) devices. Results : Intrasaccular devices have proven to be effective in treating complex aneurysms like WNAs. Conclusions : Intrasaccular flow disruptors have emerged as a new class of effective endovascular therapy, and results of ongoing clinical studies for the newer devices (e.g., SEAL and Trenza) are much anticipated.

Background and Objectives: Moyamoya disease (MMD) is a chronic steno-occlusive disease of the intracranial circulation that depends on neoangiogenesis of collateral vessels to maintain cerebral perfusion and is primarily managed with cerebral revascularization surgery. A quantitative assessment of preoperative and postoperative collateral flow using quantitative magnetic resonance angiography with noninvasive optimal vessel analysis (NOVA) was used to illustrate the impact of revascularization on cerebral flow distribution., Methods: A retrospective review of patients with unilateral MMD who underwent direct, indirect, or combined direct/indirect cerebral revascularization surgery was conducted between 2011 and 2020. Using NOVA, flow was measured at the anterior cerebral artery (ACA), ACA distal to the anterior communicating artery (A2), middle cerebral artery (MCA), posterior cerebral artery (PCA), and PCA distal to the posterior communicating artery (P2). Pial flow (A2 + P2) and collateral flow (ipsilateral [A2 + P2])-(contralateral [A2 + P2]) were measured and compared before and after revascularization surgery. Total hemispheric flow (MCA + A2 + P2) with the addition of the bypass graft flow postoperatively was likewise measured., Results: Thirty-four patients with unilateral MMD underwent cerebral revascularization. Median collateral flow significantly decreased from 68 to 39.5 mL/min ( P = .007) after bypass. Hemispheres with maintained measurable bypass signal on postoperative NOVA demonstrated significant reduction in median collateral flow after bypass ( P = .002). Median total hemispheric flow significantly increased from 227 mL/min to 247 mL/min ( P = .007) after bypass. Only one patient suffered an ipsilateral ischemic stroke, and no patients suffered a hemorrhage during follow-up., Conclusion: NOVA measurements demonstrate a reduction in pial collateral flow and an increase in total hemispheric flow after bypass for MMD, likely representing a decrease in leptomeningeal collateral stress on the distal ACA and PCA territories. Further studies with these measures in larger cohorts may elucidate a role for NOVA in predicting the risk of ischemic and hemorrhagic events in MMD., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Background and Objectives: Brainstem cavernous malformations (BCMs) are a distinct clinical entity that carry a high risk of patient morbidity because of location and risk of hemorrhage. Surgical management of these lesions requires intimate knowledge of surgical anatomy and skull base approaches. This article is intended to highlight a modern approach for the treatment of BCMs, with an emphasis on the use of the one-point technique to guide resection., Methods: We describe a case series of BCMs treated through a variety of skull base approaches, describing our decision-making strategy. We review the concept of the one-point technique focusing on the safest access to the malformation through 2 representative cases and also perform a retrospective review of 32 consecutive patients who underwent BCM resection to present outcomes and the comparison of two-point vs one-point techniques., Results: Consecutive series of 32 patients in whom the one-point technique was used is presented. In 8 patients (25%), the traditional two-point technique would suggest a different trajectory than the one-point technique. Postoperative MRI confirmed complete resection in 30 patients (95%), and 29 patients (91%) had modified Rankin Scale (0-2) at follow-up. All patients in whom the one-point technique guided a different trajectory had gross total removal of the cavernous malformation, with one patient having long-term new neurological impairment from the surgery. There were no mortalities., Conclusion: Despite surgical advances in recent decades and more widespread understanding of surgical anatomy and safe entry zones, surgical resection of BCMs remains a formidable challenge. While not necessarily the shortest access, the one-point technique offers a safe approach considering all the different modalities in our armamentarium and can be used as part of a strategy to determine the optimal approach to resect BCMs., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Objective: Skull base chordomas are rare, locally osseo-destructive lesions that present unique surgical challenges due to their involvement of critical neurovascular and bony structures at the craniovertebral junction (CVJ). Radical cytoreductive surgery improves survival but also carries significant morbidity, including the potential for occipitocervical (OC) destabilization requiring instrumented fusion. The published experience on OC fusion after CVJ chordoma resection is limited, and the anatomical predictors of OC instability in this context remain unclear., Methods: PubMed and Embase were systematically searched according to the PRISMA guidelines for studies describing skull base chordoma resection and OC fusion. The search strategy was predefined in the authors' PROSPERO protocol (CRD42024496158)., Results: The systematic review identified 11 surgical case series describing 209 skull base chordoma patients and 116 (55.5%) who underwent OC instrumented fusion. Most patients underwent lateral approaches (n = 82) for chordoma resection, followed by midline (n = 48) and combined (n = 6) approaches. OC fusion was most often performed as a second-stage procedure (n = 53), followed by single-stage resection and fusion (n = 38). The degree of occipital condyle resection associated with OC fusion was described in 9 studies: total unilateral condylectomy reliably predicted OC fusion regardless of surgical approach. After lateral transcranial approaches, 4 studies cited at least 50%-70% unilateral condylectomy as necessitating OC fusion. After midline approaches-most frequently the endoscopic endonasal approach (EEA)-at least 75% unilateral condylectomy (or 50% bilateral condylectomy) led to OC fusion. Additionally, resection of the medial atlantoaxial joint elements (the C1 anterior arch and tip of the dens), usually via EEA, reliably necessitated OC fusion. Two illustrative cases are subsequently presented, further exemplifying how the extent of CVJ bony elements removed via EEA to achieve complete chordoma resection predicts the need for OC fusion., Conclusions: Unilateral total condylectomy, 50% bilateral condylectomy, and resection of the medial atlantoaxial joint elements were the most frequently described independent predictors of OC fusion in skull base chordoma resection. Additionally, consistent with the occipital condyle harboring a significantly thicker joint capsule at its posterolateral aspect, an anterior midline approach seems to tolerate a greater degree of condylar resection (75%) than a lateral transcranial approach (50%-70%) prior to generating OC instability.

Background: Pial arteriovenous fistulas (pAVFs) are rare vascular malformations characterized by high-flow arteriovenous shunting involving a cortical arterial supply directly connecting to venous drainage without an intermediate nidus. Dural arteriovenous fistulas (dAVFs) can infrequently involve additional pial feeders which can introduce higher flow shunting and increase the associated treatment risk. In the posterior fossa, arteriovenous fistula (AVF) angioarchitecture tends to be particularly complex, involving either multiple arterial feeders-sometimes from both dural and pial origins-or small caliber vessels that are difficult to catheterize and tend to be intimately involved with functionally critical brainstem or upper cervical cord structures. Given their rarity, published experience on microsurgical or endovascular treatment strategies for posterior fossa pAVFs and dAVFs with pial supply remains limited., Methods: Retrospective chart review from 2019-2023 at a high-volume center identified six adult patients with posterior fossa pAVFs that were unable to be fully treated endovascularly and required microsurgical disconnection. These cases are individually presented with a technical emphasis and supported by comprehensive angiographic and intraoperative images., Results: One vermian (Case 1), three cerebellopontine angle (Cases 2-4) and two craniovertebral junction (Cases 5-6) posterior fossa pAVFs or dAVFs with pial supply are presented. Three cases involved mixed dural and pial arterial supply (Cases 1, 4, and 6), and one case involved a concomitant microAVM (Case 2). Endovascular embolization was attempted in four cases (Cases 1-4): The small caliber and tortuosity of the main arterial feeder prevented catheterization in two cases (Cases 1 and 3). Partial embolization was achieved in Cases 2 and 4. In Cases 5 and 6, involvement of the lateral spinal artery or anterior spinal artery created a prohibitive risk for endovascular embolization, and surgical clip ligation was pursued as primary management. In all cases, microsurgical disconnection resulted in complete fistula obliteration without evidence of recurrence on follow-up imaging (mean follow-up 27.1 months). Two patients experienced persistent post-treatment sensory deficits without significant functional limitation., Conclusions: This illustrative case series highlights the technical difficulties and anatomical limitations of endovascular management for posterior fossa pAVFs and dAVFs with pial supply and emphasizes the relative safety and utility of microsurgical disconnection in this context. A combined approach involving partial preoperative embolization-when the angioarchitecture is permissive-can potentially decrease surgical morbidity. Larger studies are warranted to better define the role for multimodal intervention and to assess associated long-term AVF obliteration rates in the setting of pial arterial involvement., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The major mechanism of morbidity of delayed cerebral ischemia after subarachnoid hemorrhage (SAH) is considered to be severe vasospasm. Quantitative MRA (QMRA) provides direct measurements of vessel-specific volumetric blood flow and may permit a clinically relevant assessment of the risk of ischemia secondary to cerebral vasospasm., Purpose: To evaluate the utility of QMRA as an alternative imaging technique for the assessment of cerebral vasospasm after SAH., Methods: QMRA volumetric flow rates of the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) were compared with vessel diameters on catheter-based angiography. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of QMRA for detecting cerebral vasospasm was determined by receiver-operating characteristic curves. Spearman correlation coefficients were calculated for QMRA flow versus angiographic vessel diameter., Results: Sixty-six vessels (10 patients) were evaluated with QMRA and catheter-based angiography. The median percent QMRA flow of all vessels with angiographic vasospasm (55.0%, IQR 34.3-71.6%) was significantly lower than the median percent QMRA flow of vessels without vasospasm (91.4%, IQR 81.4-100.4%) (p < 0.001). Angiographic vasospasm reduced QMRA-assessed flow by 23 ± 5 (p = 0.018), 95 ± 12 (p = 0.042), and 16 ± 4 mL/min (p = 0.153) in the ACA, MCA, and PCA, respectively, compared to vessels without angiographic vasospasm. The sensitivity, specificity, PPV, and NPV of QMRA for the discrimination of cerebral vasospasm was 84%, 72%, 84%, and 72%, respectively, for angiographic vasospasm >25% and 91%, 60%, 87%, and 69%, respectively, for angiographic vasospasm >50%. The Spearman correlation indicated a significant association between QMRA flows and vessel diameters ( r s  = 0.71, p < 0.001)., Conclusion: Reduction in QMRA flow correlates with angiographic vessel narrowing and may be useful as a non-invasive imaging modality for the detection of cerebral vasospasm after SAH., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Current methods for angioplasty and stenting of the intracranial vasculature for neurointervention are limited. The Wingspan Stent System is Food and Drug Administration (FDA) approved with human device exemption for a limited patient group and despite numerous prospective registries and trials demonstrating reasonable safety, still carries warnings from the FDA for its use. Given these limitations, we present the technical nuances and outcomes of the off-label use of the Resolute Onyx drug-eluting stent (DES) for neurointerventional purposes., Methods: Retrospective chart review of all patients undergoing a neurointerventional procedure with the Resolute Onyx DES was done from January 2017-2021. The Resolute Onyx is a coronary balloon-mounted drug-eluting (zotarolimus) single wire laser cut stent. Technical details and procedural outcomes were collected., Results: In total 40 patients had attempted placement of the Resolute Onyx DES with procedural success in 95% of patients. The most common vessel stented was the basilar artery, 30% (12/40). The most common indication was intracranial atherosclerotic disease in 62.5% (25/40) patients, followed by acute stroke in 17.5% (7/40) of patients. The technical and procedural outcomes were excellent with only one technical complication (2.5%)., Conclusions: This series describes the initial technical safety and utility of utilizing a new generation balloon-mounted drug-eluting stent for neurointerventional purposes. This stent offers the potential for improved navigability, delivery, and outcomes compared to current neurointerventional options and warrants further study., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Flow augmentation is the mainstay treatment for moyamoya disease as hemodynamic failure is believed to be the dominant mechanism. We aimed to investigate the mechanisms of stroke in moyamoya disease by assessing the relationship between infarction patterns and quantitative magnetic resonance angiography flow state., Methods: A retrospective study of adult patients with suspected MMD who presented with MRI confirmed acute ischemic stroke predating or following QMRA by a maximum of six months between 2009 and 2021 was conducted. Of the 177 consecutive patients with MMD who received QMRA, 35 patients, consisting of 41 hemispheres, met inclusion criteria. Flow-status was dichotomized into low-flow and normal-flow state based on previously established criteria., Results: Mixed infarction pattern was the most frequent finding (70.7 %), followed by embolic (17.1 %), perforator (7.3 %), and internal borderzone (IBZ) (4.9 %). Infarction patterns were further dichotomized into IBZ+ (internal borderzone alone or mixed) and IBZ- (no internal borderzone constituent). Low-flow states were not significantly more frequent in the IBZ+ compared to IBZ- population (48.4 % vs. 20.0 %, p = 0.14). Ipsilateral posterior cerebral artery fractional flow was significantly higher with IBZ+ compared to IBZ- (345.0 % vs. 214.7 %, p = 0.04)., Conclusion: Mixed infarction pattern was the most common pattern of infarction in patients with moyamoya disease, implying hypoperfusion and thromboembolism are codominant stroke mechanisms. An association between ICA flow status and infarction pattern was not found, although QMRA evidence of more robust posterior cerebral artery leptomeningeal collaterals was found in patients with a hypoperfusion contribution to their stroke mechanism., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest.., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Intracranial solitary fibrous tumors (SFTs), formerly hemangiopericytomas (HPCs), are rare, aggressive dural-based mesenchymal tumors. While adjuvant radiation therapy has been suggested to improve local tumor control (LTC), especially after subtotal resection, the role of postoperative stereotactic radiosurgery (SRS) and the optimal SRS dosing strategy remain poorly defined., Methods: PubMed, EMBASE, and Web of Science were systematically searched according to PRISMA guidelines for studies describing postoperative SRS for intracranial SFTs. The search strategy was defined in the authors' PROSPERO protocol (CRD42023454258)., Results: 15 studies were included describing 293 patients harboring 476 intracranial residual or recurrent SFTs treated with postoperative SRS. At a mean follow-up of 21-77 months, LTC rate after SRS was 46.4-93% with a mean margin SRS dose of 13.5-21.7 Gy, mean maximum dose of 27-39.6 Gy, and mean isodose at the 42.5-77% line. In pooled analysis of individual tumor outcomes, 18.7% of SFTs demonstrated a complete SRS response, 31.7% had a partial response, 18.9% remained stable (overall LTC rate of 69.3%), and 30.7% progressed. When studies were stratified by margin dose, a mean margin dose > 15 Gy showed an improvement in LTC rate (74.7% versus 65.7%)., Conclusions: SRS is a safe and effective treatment for intracranial SFTs. In the setting of measurable disease, our pooled data suggests a potential dose response of improving LTC with increasing SRS margin dose. Our improved understanding of the aggressive biology of SFTs and the tolerated adjuvant SRS parameters supports potentially earlier use of SRS in the postoperative treatment paradigm for intracranial SFTs., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background and Objectives: Internal jugular vein (IJV) stenosis is associated with several neurological disorders including idiopathic intracranial hypertension (IIH) and pulsatile tinnitus. In cases of extreme bony compression causing stenosis in the infracondylar region, surgical decompression might be necessary. We aim to examine the safety and efficacy of surgical IJV decompression., Methods: We retrospectively reviewed patients who received surgical IJV decompression via the extreme lateral infracondylar (ELI) approach between July 2020 and February 2022., Results: Fourteen patients with IJV stenosis were identified, all with persistent headache and/or tinnitus. Six patients were diagnosed with IIH, three of whom failed previous treatment. Of the eight remaining patients, two failed previous treatment. All underwent surgical IJV decompression via styloidectomy, release of soft tissue, and removal of the C1 transverse process (TP). Follow-up imaging showed significant improvement of IJV stenosis in eleven patients and mild improvement in three. Eight patients had significant improvement in their presenting symptoms, and three had partial improvement. Two patients received IJV stenting after a lack of initial improvement. Two patients experienced cranial nerve paresis, and one developed a superficial wound infection., Conclusion: The ELI approach for IJV decompression appears to be safe for patients who are not ideal endovascular candidates due to bony anatomy. Confirming long-term efficacy in relieving debilitating clinical symptoms requires longer follow-up and a larger patient cohort. Carefully selected patients with symptomatic bony IJV compression for whom there are no effective medical or endovascular options may benefit from surgical IJV decompression., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Despite advances in endovascular treatment, microsurgical clipping of middle cerebral artery (MCA) aneurysms remains appropriate. We review the high occlusion rate and treatment durability seen with surgical clipping of MCA aneurysms. We retrospectively reviewed patients who underwent microsurgical clipping of saccular MCA aneurysms by a single surgeon. Outcomes included aneurysm occlusion rate and durability, modified Rankin scale (mRS), and postoperative neurological morbidities. Ninety-two patients with 92 saccular MCA aneurysms were included, 50% of which were ruptured aneurysms. The mean follow-up period was 59 months. Complete aneurysm occlusion was achieved in all except one patient (99%) with near-complete occlusion. MCA aneurysm clipping was durable, with only one patient (1%) requiring retreatment after 4 years due to regrowth. Of the cohort, 79.3% achieved mRS 0-2 at last follow-up, including all with unruptured aneurysms. Poor outcome at discharge was associated with age > 65 (p = .03), postoperative neurological morbidities (p = .006), and aneurysm rupture (p < .001). Older age remained the single correlate for poor long-term outcome (p = .04). For ruptured aneurysms, predictors of poor long-term outcome included hemiparesis on presentation (p = .017), clinical vasospasm requiring treatment (p = .026), and infarction related to vasospasm (p = .041). Older age (p = .046) and complex anatomy (p = .036) were predictors of new postoperative neurological morbidities in the unruptured group. MCA aneurysm clipping is safe, durable, and should be considered first-line treatment for patients with saccular MCA aneurysms, especially in centers with abundant surgical experience., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Disappearing intracranial aneurysms are rare and have not been extensively reported in the literature. They are often small or partially thrombosed and carry a significant risk of recurrence. We discuss a unique case of a 65-year-old woman who presented in 2006 with a subarachnoid hemorrhage and was found to have a ruptured posterior communicating artery and an unruptured P1 aneurysm. Follow-up angiography and imaging showed no changes in the size of a left P1 aneurysm for 11 years (2006-2017). However, in 2021, 15 years after initial presentation, no aneurysm was seen on magnetic resonance angiography, and subsequent digital subtraction angiography in 2022 showed almost complete disappearance of the unruptured P1 aneurysm. Literature review reveals only six reported cases during which a small, unruptured anterior circulation aneurysm disappeared, or regressed on follow-up imaging and no reported cases in the posterior circulation., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.