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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.)

Background: Dural arteriovenous fistulas (dAVFs) located at craniocervical junction are extremely rare (1%-2% of intracranial/spinal dAVFs). Their angio-architectural complexity renders endovascular embolization to be challenging given multiple small feeders with risk of embolysate reflux into vertebral artery and limited transvenous access. The available literature discussing microsurgery for these lesions is limited to few case reports., Objective: To report a multicenter experience assessing microsurgery safety/efficacy., Methods: Prospectively maintained registries at 13 North American centers were queried to identify craniocervical junction dAVFs treated with microsurgery (2006-2021)., Results: Thirty-eight patients (median age 59.5 years, 44.7% female patients) were included. The most common presentation was subarachnoid/intracranial hemorrhage (47.4%) and myelopathy (36.8%) (92.1% of lesions Cognard type III-V). Direct meningeal branches from V3/4 vertebral artery segments supplied 84.2% of lesions. All lesions failed (n = 5, 13.2%) or were deemed inaccessible/unsafe to endovascular treatment. Far lateral craniotomy was the most used approach (94.7%). Intraoperative angiogram was performed in 39.5% of the cases, with angiographic cure in 94.7% of cases (median imaging follow-up of 9.2 months) and retreatment rate of 5.3%. Favorable last follow-up modified Rankin Scale of 0 to 2 was recorded in 81.6% of the patients with procedural complications of 2.6%., Conclusion: Craniocervical dAVFs represent rare entity of lesions presenting most commonly with hemorrhage or myelopathy because of venous congestion. Microsurgery using a far lateral approach provides robust exposure and visualization for these lesions and allows obliteration of the arterialized draining vein intradurally as close as possible to the fistula point. This approach was associated with a high rate of angiographic cure and favorable clinical outcomes., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: Several collateral venous pathways exist to assist in cranial venous drainage in addition to the internal jugular veins. The important extrajugular networks (EJN) are often readily identified on diagnostic cerebral angiography. However, the angiographic pattern of venous drainage through collateral EJN has not been previously compared among patients with and without idiopathic intracranial hypertension (IIH)., Objective: To quantify EJN on cerebral angiography among patients both with and without IIH and to determine whether there is a different EJN venous drainage pattern in patients with IIH., Methods: Retrospective imaging review of 100 cerebral angiograms (50 IIH and 50 non-IIH patients) and medical records from a single academic medical center was performed by 2 independent experienced neuroendovascular surgeons. Points were assigned to EJN flow from 0 to 6 using an increasing scale (with each patient's dominant internal jugular vein standardized to 5 points to serve as the internal reference). Angiography of each patient included 11 separately graded extrajugular networks for internal carotid and vertebral artery injections., Results: Patients in the IIH group had statistically significant greater flow in several of the extrajugular networks. Therefore, they preferentially drained through EJN compared with the non-IIH group. Right transverse-sigmoid system was most often dominant in both groups, yet there was a significantly greater prevalence of codominant sinus pattern on posterior circulation angiograms., Conclusion: Patients with IIH have greater utilization of EJN compared with patients without IIH. Whether this is merely an epiphenomenon or possesses actual cause-effect relationships needs to be determined with further studies., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: With recent advances in endovascular treatments of brain aneurysms such as flow diverters, the role of cerebral revascularization needs to be re-evaluated., Objective: To evaluate the contemporary indications and outcomes of cerebral revascularization for brain aneurysms., Methods: A retrospective evaluation of a prospectively maintained database was performed to review clinical and imaging data of all the patients who underwent cerebral revascularization for brain aneurysms over the past 10 yr., Results: Among 174 cerebral revascularizations, 40 (in 36 patients) were done for the treatment of aneurysms. In total, 9 patients underwent combined endovascular treatment and surgical revascularization. Immediate aneurysm occlusion was achieved in 30 patients (83.3%). Immediate postoperative bypass patency was confirmed in 33 patients (92%). Postoperative neurological deficit was observed in 4 patients (11.1%). There were 2 mortalities in the postoperative period. Aneurysm total occlusion rate was 91% at 1 yr. Thirty patients had 1 yr clinical and radiological follow-up. Clinical evaluations showed modified Rankin Scale 2 or less in 25 patients at 1 yr. Bypass patency was confirmed in 27 (90%). Patients with fair/poor outcome were all in the subarachnoid hemorrhage group. Twenty-one patients had follow-up studies for 3 yr or beyond with no evidence of stroke or aneurysm recurrence., Conclusion: Our results support that cerebral revascularization can be regarded as a viable and durable treatment option for these challenging aneurysms with acceptable morbidity. Cerebral bypass should be offered in selected cases where standard endovascular or surgical treatment is not efficacious or curative., (© Congress of Neurological Surgeons 2021.)

Surgical treatment of large vestibular schwannomas is challenging. Both facial and cochlear nerves should be preserved in patients who have no neurological deficit preoperatively. In this 3-dimensional video, we present a 35-yr-old patient who presented with documented increase in the size of a known vestibular schwannoma over the span of 3 yr. Surgery was favored among all treatment options due to his young age and the tumor size. Informed consent was obtained. Semisitting surgery allowed for bimanual microdissection of the tumor capsule from the surrounding arachnoid and cranial nerves with 2 micro dissectors. The precision of microdissection is enhanced in the sitting position. Facial nerve stimulation remained stable at 0.05 mA. The auditory evoked potential remained unchanged during the surgery. Complete resection of the tumor and preservation of facial and cochlear nerves was achieved. The patient had a stable hearing grade B and a normal facial nerve function at 3-mo follow-up., (© Congress of Neurological Surgeons 2021.)

Large middle cerebral artery (MCA) bifurcation aneurysms are known vascular lesions that are usually symptomatic but often difficult to treat (whether with open or endovascular techniques), especially when the M2 branches originate from the aneurysm dome.1-7 The challenge lies in securing the aneurysm while fully maintaining the flow in the vessels arising from the dome. Standard microsurgical clipping or endovascular techniques are not feasible in perfectly treating these aneurysms. Revascularization of the MCA branches with bypass and trapping of the aneurysm is often necessary. Here, we present a case of a large complex partially thrombosed right MCA bifurcation aneurysm with both the superior and the inferior divisions arising from the dome. The patient initially presented with a right MCA stroke and left hemiparesis. Using radial artery as an interposition graft, 2 bypasses-internal maxillary artery to the inferior division and superficial temporal artery to the superior division-were performed. The aneurysm was trapped and decompressed by placing clips at the M1 terminus and the M2 origins. Intraoperative angiography and postoperative NOVA (VasSol Inc.) magnetic resonance angiography (MRA) confirmed patency and excellent flow in the bypass grafts. The patient's postoperative course was uncomplicated, and at 2-mo follow-up, had significant improvement of her hemiparesis. The patient provided informed consent for the procedure., (© Congress of Neurological Surgeons 2021.)

Background: The surgical approaches to the region of the cerebello-mesencephalic sulcus and superior cerebellar peduncle (SCP) remain a neurosurgical challenge., Objective: To present the use of the extreme lateral supracerebellar infratentorial (SC-IT) approach to treat arteriovenous malformations (AVMs) of the SCP, which is a different entity compared to brainstem AVMs., Methods: We treated 4 patients with SCP AVMs in the last 5 yr at our institution. The mean age was 49.7 yr. The average nidus size was 2.12 cm. Of those, 3 patients presented with hemorrhage and 1 with headache and tinnitus. Extreme lateral SC-IT approach was used in all cases., Results: Complete resection was achieved in all cases as verified with postoperative angiogram. In 1 case, intraoperative rupture with intraventricular hemorrhage was encountered, and the patient required temporary external ventricular drainage. There was no permanent complication or neurological deficit. The modified Rankin Scale (at discharge or follow-up) was less than 2 in all cases., Conclusion: The AVMs located primarily in the SCP are distinct compared to brainstem AVMs, and their management should be different. Extreme lateral SC-IT approach should be considered as a viable alternative surgical approach for resection of these AVMs, and excellent surgical results can be achieved., (© Congress of Neurological Surgeons 2021.)

Background: Internal maxillary artery (IMax) is a relatively new donor vessel used in the extracranial-intracranial bypass surgery. However, unfamiliarity and relatively elaborate techniques of its harvest precluded its widespread use., Objective: To present a simplified technique of IMax harvest based on constant anatomical landmarks without the need of extensive skull-base drilling while providing adequate space for proximal anastomosis., Methods: Cadaveric dissection on 4 cadaveric heads (8 sides) was performed. Zygomatic osteotomy was performed and temporal muscle was dissected off the zygomatic process of the frontal bone and the frontal process of the zygomatic bone and reflected inferiorly into the bony gap created by the zygomatic osteotomy. Posterior wall of the maxilla (PWoM) was palpated. Following PWoM inferiorly leads to pterygo-maxillary fissure (PMF), which is a constant landmark IMax passes through., Results: IMax was localized following this technique before its entrance into PMF in every specimen. Proximal dissection was carried on to the exposed adequate length of the vessel. Depending on the relationship with the lateral pterygoid muscle, this might need to be incised to allow for identification of the IMax. After its transection, proximal stump is mobilized superiorly into the surgical field. Clinical application of this technique was demonstrated on an aneurysm case., Conclusion: Using the palpation of the PWoM as a landmark for localization of PMF facilitates harvesting of IMax without need for extensive skull-base drilling and shortens the time of the surgery., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background: Large vestibular schwannomas (VSs) with brainstem compression are generally reserved for surgical resection. Surgical aggressiveness must be balanced with morbidity from cranial nerve injury. The purpose of the present investigation is to evaluate the clinical presentation, management modality, and patient outcomes following near total resection (NTR) vs gross total resection (GTR) of large VSs., Objective: To assess facial nerve outcome differences between GTR and NTR patient cohorts., Methods: Between January 2010 and March 2018, a retrospective chart review was completed to capture patients continuously who had VSs with Hannover grades T4a and T4b. NTR was decided upon intraoperatively. Primary data points were collected, including preoperative symptoms, tumor size, extent of resection, and postoperative neurological outcome., Results: A total of 37 patients underwent surgery for treatment of large and giant (grade 4a and 4b) VSs. Facial nerve integrity was preserved in 36 patients (97%) at the completion of surgery. A total of 27 patients underwent complete resection, and 10 had near total (>95%) resection. Among patients with GTR, 78% (21/27) had House-Brackmann (HB) grade I-II facial nerve function at follow-up, whereas 100% (10/10) of the group with NTR had HB grade I-II facial nerve function. Risk of meningitis, cerebrospinal fluid leak, and sinus thromboses were not statistically different between the 2 groups. There was no stroke, brainstem injury, or death. The mean follow-up was 36 mo., Conclusion: NTR seems to offer a benefit in terms of facial nerve functional outcome compared to GTR in surgical management of large VSs without significant risk of recurrence., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Sylvian arteriovenous malformations (AVMs) are challenging lesions for surgical management. They are classified according to the Sugita classification based on the location of the nidus in the sylvian fissure: pure, lateral, medial, and deep. Resection of these lesions are fraught with risks, as it requires extensive arachnoid dissection in the sylvian fissure in close proximity to surrounding eloquent tissue, and the presence of en passage arteries can resemble feeding arteries. In this video illustration, the authors describe a complex, Spetzler-Martin Grade IV right sylvian AVM and its surgical resection. By Sugita classification, this was a medial sylvian AVM, with an associated flow related middle cerebral artery (MCA) bifurcation aneurysm. Informed consent was obtained from the patient prior to the procedures. The AVM was embolized preoperatively, and surgical resection was carried out via a pterional approach. The detail of the AVM resection is described in the video clip. Postoperative digital subtraction angiography showed complete excision of the lesion, and the patient was discharged to home on postoperative day 6 without any neurological deficit. In 1-yr follow-up angiogram, beside complete obliteration of the AVM, the flow-related MCA bifurcation aneurysm as well as the M1 and M2 vessels have decreased in size and are much less prominent in comparison to the pretreatment angiography., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Flow-replacement revascularization and/or flow augmentation surgery may be necessary for safe deconstruction of complex middle cerebral artery (MCA) aneurysms. Roughly 1% to 2% of all MCA aneurysms have angiographic features prohibiting standard microsurgical or endovascular management. Consent was obtained from the patient for the production of this video. No International Review Board approval was required for the creation of this video. A 17-yr-old female presented at the age of 15 with headaches. At the time of initial presentation, the patient was found to have an MCA bifurcation aneurysm. Initially, the aneurysm was managed conservatively and followed. However, on follow-up imaging, the aneurysm was found to have grown and developed into a large, complex MCA bifurcation aneurysm. Patient underwent planned trapping and deconstruction of the aneurysm. An internal maxillary artery (IMAX) to MCA bypass was performed using a cephalic vein graph to a robust inferior MCA branch combined with an in Situ MCA to MCA bypass. Follow-up angiography showed complete occlusion of the aneurysm. Patient was neurologically intact at 1-yr follow-up. Microsurgery continues to be the best treatment option for complex MCA aneurysms. A surgeon trained in bypass is an absolute prerequisite for management of those lesions. The IMAX offers an ideal high flow donor vessel for subcranial to intracranial flow replacement, which was required for re-establishment of flow to the robust inferior MCA branch in this case. The superior branch of the MCA was less robust. Therefore, by recreating a more distal bifurcation, the in Situ side-to-side MCA-MCA bypass simplified the revascularization strategy., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: The role of expanded endonasal endoscopic surgery for primary and recurrent craniopharyngioma is not yet fully established., Objective: To report and evaluate our experience with the endoscopic endonasal approach (EEA) for the resection of primary and recurrent craniopharyngiomas., Methods: This is a retrospective cohort analysis of 43 consecutive EEA procedures in 40 patients operated from September 2006 to February 2012 for suprasellar craniopharyngiomas. In 21 patients (48.8%) the disease was recurrent. We have assessed the surgical results, visual, endocrinological, and functional outcomes and resection rates in this patient cohort., Results: At presentation, 31 (72.1%) patients had visual deficits, 15 patients (34.9%) complained of headaches, 25 patients (58.1%) had anterior pituitary insufficiency, and 14 (32.5%) had diabetes insipidus. Total resection was achieved in 44.2% surgeries, of which 77.3% were in primary lesions and 9.5% in recurrent lesions (P < .001). Vision improved in 92.6% patients and worsened in 2.3%. Complications other than vision were encountered in 25.6% including 9/43 cerebrospinal fluid leak, 2/43 meningitis. A total of 51.9% of patients with preoperative residual anterior pituitary function had new anterior pituitary deficiencies and 42.8% had new diabetes insipidus. There was no mortality. Six patients (14%) had recurrence of disease during the follow-up period (mean 56.8 mo), 5 of which required repeat surgery., Conclusion: The EEA can be integrated in the overall management of both primary and recurrent craniopharyngiomas with good results; however, in our series recurrent surgery was associated with significantly lower rates of gross total resection., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: For some posterior inferior cerebellar artery (PICA) aneurysms, there is no constructive endovascular or direct surgical clipping option. Intracranial bypass is an alternative to a deconstructive technique., Objective: To evaluate the clinical features, surgical techniques, and outcome of PICA aneurysms treated with bypass and obliteration of the diseased segment., Methods: Retrospective review of PICA aneurysms treated via intracranial bypass was performed. Outcome measurements included postoperative stroke, cranial nerve deficits, gastrostomy/tracheostomy requirement, bypass patency, modified Rankin scale (mRS) at discharge, and mRS at 6 mo., Results: Seven patients with PICA aneurysms treated with intracranial bypass were identified. Five had fusiform aneurysms (4 ruptured, 1 unruptured), 1 had a giant partially thrombosed saccular aneurysm (unruptured), and 1 had a dissecting traumatic aneurysm (ruptured). Two aneurysms were at the anteromedullary segment, 4 at the lateral medullary segment, and 1 at the tonsillomedullary segment. Three patients underwent PICA-to-PICA side to side anastomoses, 2 PICA-to-PICA reanastomosis, 1 vertebral artery-to-PICA bypass, and 1 occipital artery-PICA bypass. Six out of 7 aneurysms were obliterated surgically and 1 with additional endovascular occlusion after the bypass. All bypasses were patent intraoperatively; 2 were later demonstrated occluded without radiological signs or symptoms of stroke. No patients had new cranial nerve deficit postoperatively. With the exception of 1 death due to pulmonary emboli 3 mo postoperatively, all others remain at a mRS ≤ 2., Conclusion: Constructive bypass and aneurysm obliteration remains a viable alternative for treatment of PICA aneurysms not amenable to direct surgical clipping or to a vessel-preserving endovascular option., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: Intraoperative angiography is routinely utilized for aneurysms and arteriovenous malformations (AVMs) to verify complete occlusion and resection. Surgery for spinal and posterior fossa neurovascular lesions is usually performed in prone position. Intraoperative angiography in the prone position is challenging and there is no standardized protocol for this procedure., Objective: To describe our experience with intraoperative angiography in the prone and lateral positions, using upper extremity arterial access., Methods: We reviewed our experience with intraoperative angiography in the prone position between 2014 and 2015, where vascular access was obtained via the upper extremity arteries. Patients were treated in a hybrid endovascular operating room. High cervical and intracranial lesions were studied via brachial or radial access. All accesses were obtained using ultrasonographic guidance and a small caliber arterial sheath (4F)., Results: Five patients were treated in the prone and lateral positions using brachial/radial artery access. Patients harbored cerebellar AVM, lateral medullary AVM, cervical arteriovenous fistula (AVF), tentorial dural AVF, and tentorial-incisural dural AVF. Patients were positioned prone (n = 2), semiprone (n = 2), and lateral (n = 1) for the surgery. Three patients were treated via right brachial artery access. Two patients were treated via radial arteries access. All patients tolerated the procedures without technical or clinical complications. Intraoperative angiography verified complete occlusion and resection in all cases prior to surgical closure., Conclusions: Intraoperative angiography in the prone and lateral positions using upper extremity access is an important adjunct. Brachial or radial access can be obtained safely and provides comfortable and quick approaches., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: The cervical carotid system has been used as a source of donor vessels for radial artery or saphenous vein grafts in cerebral bypass. Recently, internal maxillary artery to middle cerebral artery bypass has been described as an alternative, with reduction of graft length potentially correlating with improved patency., Objective: To describe our experience using the forearm cephalic vein grafts for short segment internal maxillary artery to middle cerebral artery bypasses., Methods: All vein grafts were harvested from the volar forearm between the proximal cubital fossa where the median cubital vein is confluent with the cephalic vein and the distal wrist., Results: Six patients were treated with internal maxillary artery to middle cerebral artery bypass. In 4, the cephalic vein was used. Postoperative angiography demonstrated good filling of the grafts with robust distal flow. There were no upper extremity vascular complications. All but 1 patient (mortality) tolerated the procedure well. The other 3 patients returned to their neurological baseline with no new neurological deficit during follow-up., Conclusion: The internal maxillary artery to middle cerebral artery "middle" flow bypass allows for shorter graft length with both the proximal and distal anastomoses within the same microsurgical field. These unique variable flow grafts represent an ideal opportunity for use of the cephalic vein of the forearm, which is more easily harvested than the wider saphenous vein graft and which has good match size to the M1/M2 segments of the middle cerebral artery. The vessel wall is supple, which facilitates handling during anastomosis. There is lower morbidity potential than utilization of the radial artery. Going forward, the cephalic vein will be our preferred choice for external carotid-internal carotid transplanted conduit bypass.

Background: Internal maxillary artery (IMax)-middle cerebral artery (MCA) bypass has been recently described as an alternative to cervical extracranial-intracranial bypass. This technique uses a "keyhole" craniectomy in the temporal fossa that requires a technically challenging end-to-side anastomosis., Objective: To describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax to facilitate bypass., Methods: Orbitozygomatic osteotomy is used followed by frontotemporal craniotomy and subsequently laterotemporal fossa craniectomy, reaching its medial border at a virtual line connecting the foramen rotundum and foramen ovale. The IMax was identified by using established anatomic landmarks, neuronavigation, and micro Doppler probe (Mizuho Inc. Tokyo, Japan). Additionally, we studied the approach in a cadaveric specimen in preparation for microsurgical bypass., Results: There were 4 cases in which the technique was used. One bypass was performed for flow augmentation in a hypoperfused hemisphere. The other 3 were performed as part of treatment paradigms for giant middle cerebral artery aneurysms. Vein grafts were used in all patients. The proximal anastomosis was performed in an end-to-side fashion in 1 patient and end-to-end in 3 patients. Intraoperative graft flow measured with the Transonic flow probe ranged from 20 to 60 mL/min. Postoperative angiography demonstrated good filling of the graft with robust distal flow in all cases. All patients tolerated the procedure well., Conclusion: IMax to middle cerebral artery subcranial-intracranial bypass is safe and efficacious. The laterotemporal fossa craniectomy technique resulted in reliable identification and wide exposure of the IMax, facilitating the proximal anastomosis.

Background: Brainstem arteriovenous malformations are challenging lesions, and benefits of treatment are uncertain., Objective: To study the clinical course of Brainstem arteriovenous malformations and the influence of treatments on outcome., Methods: We reviewed a prospective series of 31 brainstem arteriovenous malformations. Demographic, morphological, and clinical characteristics were recorded. Factors determining initial and final outcomes (modified Rankin Scale), results of treatments (cure rates, complications), and disease course were analyzed., Results: Brainstem arteriovenous malformations were symptomatic and bled in 93% and 61% of cases, respectively. Examination was abnormal and initial modified Rankin Scale score was < 3 in 71% and 86% of patients, respectively. The average follow-up time was 6.2 years, and 26% of patients rebled (5.9 %/y). Treatment modalities included conservative, radiosurgical, endovascular, surgical, and multimodality treatment in 13%, 58%, 35%, 16%, and 26% of cases, respectively. The obliteration rate was 60% overall and 39% after radiosurgery, 40% after embolization, and 75% after microsurgery, with respective complication-free cure rates of 71%, 50%, and 0%. Overall procedural mortality and morbidity were 2.3% and 18.6%, respectively. Final modified Rankin Scale score was < 3 in 77% of cases. Neurological deterioration (35%) was related to treatment complications in 74% of cases with a negative impact of surgery (P = .04), palliative embolization (odds ratio = 16), and multimodality treatments (odds ratio = 24). Radiosurgery was inversely associated with worsening (odds ratio = 0.06)., Conclusion: Brainstem arteriovenous malformations require individualized treatment decisions. Single-modality treatments with a reasonable chance of complete cure and low complication rate (such as radiosurgery) should be favored.

Background: Multidetector computerized tomography angiography (MDCTA) is now a widely accepted technique for the management of intracranial aneurysms., Objective: To evaluate its accuracy for the postoperative assessment of clipped intracranial aneurysms., Methods: We analyzed a consecutive series of 31 patients that underwent direct surgical clipping procedures of 38 aneurysms. A 64 slice MDCT scanner (Aquilion 64, Toshiba) was used and results were compared with digital subtraction angiographies (DSA). Two independent neuroradiologists analyzed the following data: examination quality, artifacts, aneurysm remnant, and patency of collateral branches. Interobserver agreement, sensitivity, and specificity were calculated., Results: Seventy-nine percent of the aneurysms were located in the anterior circulation. Significant artifacts were found with multiple and cobalt-alloy clips. According to DSA, remnants >2 mm were found in 21% of the cases, and 2 patients had one collateral branch occluded. Sensitivity and specificity of 64-MDCTA for the detection of aneurysm remnants were 50% and 100%, respectively. Sensitivity and specificity of 64-MDCTA for the detection of a significant remnant (>2 mm) and the detection of the occlusion of a collateral branch were, respectively, 67% and 100% and 50% and 100%. No relationship was found with the location, type, shape, size, or number of clips, but missed remnants tended to be larger with cobalt-alloy clips., Conclusions: 64-MDCTA is a valuable technique to assess the presence of a significant postoperative remnant in single titanium clip application cases and might be useful for long-term follow-up. DSA remains the most accurate postoperative radiological examination.

Objective: To evaluate the feasibility of the direct visualization of the distal dural ring (DDR) and adjacent anatomic structures in patients with paraclinoid internal carotid artery aneurysms at 3-T magnetic resonance imaging (MRI)., Methods: Six consecutive patients (1 man, 5 women; mean age, 45.5 years; age range, 34-51 years) who underwent a 3-T MRI examination for the evaluation of 7 paraclinoid carotid artery aneurysms were reviewed retrospectively. MRI scans were acquired using a T2 turbo-spin echo sequence with 2-mm thickness without gap on the coronal plane perpendicular to the diaphragma sellae. Identifications of the DDR, adjacent regional anatomic landmarks, and paraclinoid aneurysms were analyzed. The locations of the paraclinoid aneurysms were categorized into intradural (aneurysm neck and sac located above the DDR), transdural (aneurysm neck or sac were straddling the DDR), and extradural (aneurysm neck and sac located below the DDR). Interstudy agreement between computed tomographic angiography and 3-T MRI for the anatomic location of the paraclinoid aneurysms was assessed in 6 patients who underwent both examinations., Results: In all cases, the DDR was clearly identified and the relationship between the DDR and the paraclinoid aneurysm was successfully determined on 3-T MRI. The aneurysm locations determined with 3-T MRI were 4 intradural and 3 extradural. A comparison between computed tomographic angiography and 3-T MRI revealed discordant anatomic locations in 3 aneurysms (3 of 6, 50%)., Conclusion: Direct visualization of the DDR as well as precise evaluation of paraclinoid aneurysm location with high-resolution 3-T MRI is possible. This study shows that high-resolution 3-T MRI is an important means to determine the appropriate management for patients with paraclinoid aneurysms.

Objective: The traditional boundaries of the transsphenoidal approach can be expanded to include the region from the cribriform plate of the anterior cranial fossa to the foramen magnum in the anteroposterior plane. The introduction of endoscopy to transsphenoidal surgery, with its improved illumination and wider field of view, has added significant further potential for the resection of a variety of cranial base lesions. We review our experience with the expanded endoscopic endonasal approach in a series of 22 patients with anterior cranial base and supradiaphragmatic lesions., Methods: From June 2005 to June 2007, the expanded endoscopic endonasal approach was used in 22 patients with the following pathologies: 6 craniopharyngiomas; 4 esthesioneuroblastomas; 3 giant pituitary macroadenomas; 2 suprasellar Rathke's pouch cysts; 2 angiofibromas; and 1 each of suprasellar meningioma, germinoma, ethmoidal carcinoma, adenoid cystic carcinoma, and large suprasellar arachnoid cyst. This study specifically focused on the surgical indications and approaches to these lesions and the surgical results, complications, and limitations associated with this technique., Results: Gross total tumor removal, as assessed by postoperative magnetic resonance imaging, was possible in the majority of patients (73%), with the exception of the craniopharyngioma group, in which only 1 lesion was completely removed. There were no permanent neurological complications except for increased visual disturbance in 1 patient. Other complications included cerebrospinal fluid fistulae in 4 patients (18%) and meningitis in 1 patient (5%). There was no operative mortality. Large lesions, significant lateral extension, encasement of neurovascular structures, and brain invasion in malignant lesions are considered some of the contraindications for this technique., Conclusion: The expanded endoscopic endonasal approach is a promising minimally invasive alternative to open transcranial approaches for selective lesions of the midline anterior cranial base. The avoidance of craniotomy and brain retraction and reduced neurovascular manipulation with less morbidity are potential advantages. Major complications have been few, but there are also limitations with this technique. This approach should be included in the armamentarium of cranial base surgeons and considered as an option in the management of selected patients with these complex pathologies.

Objective: We report our recent experience with an expanded purely endoscopic endonasal approach for the treatment of clival chordomas., Methods: Twelve patients underwent an expanded endoscopic approach for excision of cranial base chordomas at Toronto Western Hospital. Two patients had undergone a previous craniotomy for excision of a significant lateral intracranial extension of the tumor. All other patients had mainly centrally located lesions. Three patients had recurrent tumors. This study focused on the surgical approach, results, and complications associated with this approach., Results: Diplopia caused by VIth nerve palsy was the most common presenting symptom and was observed in seven patients. Gross total resection of the tumor was achieved in seven patients (58%). Four patients had complete recovery of their preoperative diplopia. One patient (8%) presented with new hemiparesis postoperatively. Four patients (33%) had a cerebrospinal fluid leak postoperatively; two were treated by lumbar drainage, and two required a secondary surgical repair. All newly diagnosed patients underwent adjuvant radiotherapy. There was no mortality. The short-term outcome was excellent in all but one patient. No recurrence was observed at the median follow-up period of 16 months., Conclusion: The expanded endoscopic endonasal approach is a valid minimally invasive alternative for the treatment of centrally located clival chordomas or as an adjunct for the central part of chordomas with lateral extension. The early results of this technique indicate at least equivalency to more extensive open approaches, and its versatility may widen the horizon of surgical management of these aggressive lesions. The challenge with the cerebrospinal fluid leakage is being addressed with novel local flap repair techniques. This approach should be in the armamentarium of cranial base surgeons as an option in the management of clival chordomas.

The frontobasal interhemispheric approach for suprasellar tumors currently incorporates technological advancements and refinements in patient selection, operative technique, and postoperative care. This technique is a valid choice for the removal of suprasellar lesions with extension into the third ventricle without major sequelae related to the surgical approach. The method described here reflects the combination of the frontal interhemispheric and trans-lamina terminalis approaches.

Objective: The aim of this study was to report the results of a consecutive series of patients undergoing pituitary surgery using a pure endoscopic endonasal approach and to evaluate the efficacy and safety of this procedure., Patients and Methods: We reviewed 200 consecutive patients with pituitary adenoma who underwent purely endoscopic transsphenoidal resection of their lesions. The patients' clinical outcomes, including remission rates, degrees of tumor removal, and complications, were evaluated and compared with a previous microscopic series., Results: There were 111 nonfunctioning adenomas and 34 growth hormone-secreting, 27 adrenocorticotropin hormone-secreting, 25 prolactin-secreting, and 3 thyroid-stimulating hormone-secreting adenomas. The degree of gross total removal for tumors with suprasellar or parasellar extension and without cavernous sinus involvement was 96% and for intrasellar lesions was 98%. After a median follow-up period of 19 months, the remission results for patients with functioning adenomas were 71% for growth hormone-secreting, 81% for adrenocorticotropin hormone-secreting, and 88% for prolactin-secreting adenomas, with no recurrence at the time of the last follow-up. This compares with similar results reported from series using a standard microsurgical approach (growth hormone-secreting adenomas, 67%; adrenocorticotropin hormone-secreting adenomas, 78%; and prolactin-secreting adenomas, 62%). Endoscopic surgery for recurrent or residual nonfunctioning adenomas that had been previously treated using a microscopic approach revealed in the majority of cases a more limited exposure during the initial surgery, frequently with incomplete tumor removal. Complication rates have been low, and the average length of hospital stay was reduced., Conclusion: A purely endoscopic approach for pituitary adenoma treatment is a safe and effective alternative to the traditional microscopic procedure. Although our results reveal excellent tumor-removal rates, comparable remission rates in functioning tumors, and a very low rate of complications, additional studies with longer follow-up periods are required to confirm whether this approach should be considered the preferred procedure for pituitary surgery.

The frontobasal interhemispheric approach for suprasellar tumors currently incorporates technological advancements and refinements in patient selection, operative technique, and postoperative care. This technique is a valid choice for the removal of suprasellar lesions with extension into the third ventricle without major sequelae related to the surgical approach. The method described here reflects the combination of the frontal interhemispheric and trans-lamina terminalis approaches.