Temporal lobe injury with middle fossa approach to intracanalicular vestibular schwannomas: a systematic review.

There are several surgical approaches for vestibular schwannoma (VS) resection. However, management has gradually shifted from microsurgical resection, toward surveillance and radiosurgery. One of the arguments against microsurgery via the middle fossa approach (MFA) is the risk of temporal lobe retraction injury or sequelae. Here, we sought to evaluate the incidence of temporal lobe retraction injury or sequela from a MFA via a systematic review of the existing literature. This systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Relevant studies reporting temporal lobe injury or sequela during MFA for VS were identified. Data was aggregated and subsequently analyzed to evaluate the incidence of temporal lobe injury. 22 studies were included for statistical analysis, encompassing 1522 patients that underwent VS resection via MFA. The overall rate of temporal lobe sequelae from this approach was 0.7%. The rate of CSF leak was 5.9%. The rate of wound infection was 0.6%. Meningitis occurred in 1.6% of patients. With the MFA, 92% of patients had good facial outcomes, and 54.9% had hearing preservation. Our series and literature review support that temporal lobe retraction injury or sequelae is an infrequent complication from an MFA for intracanalicular VS resection.

Endoscopic endonasal obliteration of the frontal recess and anterior skull base.

BACKGROUND: Although endoscopic techniques have become more widespread in repair of frontal sinus (FS) defects, certain pathologies still require open approach (extensive trauma or tumors). Under certain circumstances even multiple complex open reconstructive procedures might fail to resolve persistent pneumocephalus or CSF leak and subsequently surgeons tend to escalate the invasiveness and employ even more complex and aggressive approaches. We present our experience treating persistent pneumocephalus or CSF leak after previously failed transcranial reconstruction utilizing an endoscopic endonasal approach (EEA). METHODS: We retrospectively reviewed a prospectively maintained database of all patients undergoing an EEA for repair of persistent pneumocephalus or CSF leak following FS cranialization between 2016 and 2020. RESULTS: Six patients who underwent cranialization of the FS with subsequent persistent pneumocephalus or CSF leak were identified; two patients suffered a traumatic fracture of the FS, remaining four patients had undergone previous cranial surgery. Clear violation of the FS was not recognized in one patient. All patients underwent cranialization of the FS either directly following initial craniotomy or during open repair of a FS fracture. Two patients underwent multiple transcranial surgeries including using vascularized free tissue transfer. Complete cessation of pneumocephalus/CSF leak was achieved in 83.3% (5/6) after the first and 100% (6/6) after two endoscopic procedures. No morbidity or mortality resulted from the endoscopic procedure. CONCLUSIONS: Skull base defects following a failed cranialization of FS are usually located in or in close proximity to the frontal recess. These defects can be safely and effectively repaired via an EEA.

Clival-Meckel's Cave Angle: A Predictor of Glycerol Displacement in Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia.

BACKGROUND AND OBJECTIVES: Percutaneous glycerol rhizotomy successfully treats trigeminal neuralgia although failure rates and durability of the procedure are variable. Some of this variability in clinical outcome might be due to egress of glycerol from Meckel's cave (MC) because of surgical positioning and individual patient anatomy. In this article, we quantitatively analyzed the anatomic variances that affect glycerol fluid dynamics to better predict patients more amenable for percutaneous glycerol injections. METHODS: Computed tomography imaging of 11 cadaveric heads was used to calculate bilateral Clival-Meckel's cave (CMC) and sella-temporal (ST) angles. Twenty-two cadaveric percutaneous injections of dyed glycerol into the Meckel's cave were performed using Härtel's approach, and the fluid movement was documented at prespecified intervals over 1 hour. The relationship between the angles and glycerol migration was studied. RESULTS: Specimens with basal cistern involvement by 60 minutes had significantly greater CMC angles (median [IQR]: basal cistern involvement = 74.5° [59.5°-89.5°] vs no basal cistern involvement = 58.0° [49.0°-67.0°]), U = 6.0, P < .001. This model may predict which patients will experience glycerol migration away from the Gasserian ganglion (area under the curve: 0.950, SE: 0.046, CI: 0.859-1.041, P < .001). Increased ST angle was associated with lateral flow of glycerol (r s = 0.639, P = .001), and CMC angle was associated with total area of dispersion (r s = -0.474, P = .026). CONCLUSION: Anatomic variation in skull base angles affects glycerol migration. Specifically, a more obtuse CMC angle was associated with a higher risk of posterior migration away from the Gasserian ganglion. This may be a reason for differing rates of surgical success. These results suggest that anterior head flexion for 60 minutes may prevent percutaneous glycerol rhizotomy failures and some patients with large CMC angles are more likely to benefit from postinjection head positioning. However, this clinical effect needs validation in vivo.

Nasofrontal meningiomas: retrospective series and review of literature.

INTRODUCTION: Lesions affecting the anterior skull base and involving the paranasal sinuses (PNS), nasal cavity (NC), and orbit are infrequent and include predominantly a wide variety of sinonasal malignancies. Less than 3% of intracranial meningiomas extend extracranially and involve PNS and NC. Given their relatively low incidence, little is known about the treatment outcome of this subset of meningiomas. METHODS: Systematic literature and retrospective review of own institutional series of midline anterior skull base meningiomas with significant PNS and NC involvement were performed. RESULTS: Overall, 21 patients-16 in the literature review group and 5 of our institutional series-were included. Eleven (52.4%) patients had had a prior surgery for midline anterior skull base meningioma. Of patients having reported WHO grade, two were WHO II. Gross total resection was achieved in 16 (76.2%) of patients, utilizing solely transcranial approach in 15 patients, combined endoscopic and transcranial in five patients and purely endoscopic in one patient. Postoperative radiotherapy was administered in three (14.3%) patients, all after total resection via transcranial route, without a history of prior treatment. A postoperative cerebrospinal fluid leak was reported in four (10%) patients, requiring surgical repair in two. There were no reports of postoperative meningitis. No neurological complications were observed except of a reported worsening of vision in one patient. CONCLUSION: Midline anterior skull base meningiomas infrequently extend significantly into the PNS and NC. Despite their significant involvement, along with concomitant involvement of orbit, gross total resection is possible in the majority of cases with low morbidity using either purely transcranial or combined endoscopic/transcranial approach.

Endoscopic Placement of Intracystic Catheters: A Technical Note.

BACKGROUND: Intraventricular neuroendoscopic surgery for tumor resection, biopsy, or cyst fenestration frequently requires precise placement of an intraventricular or intracystic catheter. Placement under direct visualization is not feasible because of small bore of working channel of the standard small ventriculoscope. Various techniques have been reported using a separate transcortical trajectory, endoluminal endoscope, or endovascular guide wire. OBJECTIVE: To describe a technique allowing precise placement of intraventricular/intracystic catheter using a small bore working ventriculoscope, without need for additional equipment. METHODS: Description of the technique including intraoperative photographs, video, and illustrative cases are provided. RESULTS: The peel-away sheath is peeled off approximately 1 to 2 cm to allow for the shaft of the endoscope to pass past its tip. Ventricular access is gained using the peel-away sheath. After the stylet is removed, the peel-away sheath is not peeled further or stapled to the skin. The endoscope is introduced into the ventricle through the peel-away sheath. After the required intraventricular work is performed, the endoscope is maneuvered into the location of the desired catheter position. The peel-away sheath is slowly advanced over the stationary endoscope past its tip. While the peel-away sheath is being held in place, the endoscope is removed. After the catheter has been introduced into the peel-away sheath to a premeasured depth, the peel-away sheath is peeled and removed. The catheter is then connected to collection system, reservoir or shunt system. CONCLUSION: The current technique allows for the precise placement of intraventricular/intracystic catheters without the need for additional equipment or a separate transcortical trajectory.

Preliminary experience with diffuse correlation spectroscopy in acute ischemic stroke neurointerventional procedures.

BACKGROUND: Diffuse correlation spectroscopy (DCS) is a non-invasive optical technique that enables continuous blood flow measurements in various organs, including the brain. DCS quantitatively measures blood flow from temporal fluctuations in the intensity of diffusely reflected light caused by the dynamic scattering of light from moving red blood cells within the tissue. METHODS: We performed bilateral cerebral blood flow (CBF) measurements using a custom DCS device in patients undergoing neuroendovascular interventions for acute ischemic stroke. Experimental, clinical, and imaging data were collected in a prospective manner. RESULTS: The device was successfully applied in nine subjects. There were no safety concerns or interference with the standard angiography suite or intensive care unit workflow. Six cases were selected for final analysis and interpretation. DCS measurements with photon count rates greater than 30 KHz had sufficient signal-to-noise to resolve blood flow pulsatility. We found an association between angiographic changes in cerebral reperfusion (partial or complete reperfusion established in stroke thrombectomy cases; temporary flow arrest during carotid artery stenting) and those observed intraprocedurally with CBF measurements via DCS. Limitations of the current technology included sensitivity to the interrogated tissue volume under the probe and the effect of local changes in tissue optical properties on the accuracy of CBF estimates. CONCLUSION: Our initial experience with DCS in neurointerventional procedures showed the feasibility of this non-invasive approach in providing continuous measurement of regional CBF brain tissue properties.

Optimizing Workflow in Combined Petrosectomy Approaches: Surgical Technique and Case Series.

BACKGROUND AND OBJECTIVE: The combined petrosectomy is one of the workhorse skull base approaches to the petroclival region. Traditionally, this approach starts with a temporosuboccipital craniotomy, followed by the mastoidectomy/anterior petrosectomy, and completed with the dural opening/tumor resection. This sequence of events (neurosurgery-neuro-otology-neurosurgery) involves at least 2 handoffs and change of surgical teams and instrumentation. This report describes a resequencing of events and a modification of the technique used to craft the temporosuboccipital craniotomy, with aims to reducing handoffs between surgical teams and improving operating room workflow. METHODS: Adhering to PROCESS guidelines, a case series is provided in addition to the surgical technique and surgical images. RESULTS: The technique for performing a combined petrosectomy is described with illustrations. This description shows that the temporal bone drilling may be performed before the craniotomy to allow for direct visualization of the dura and sinuses before completing the craniotomy. In doing so, only 1 transition between the otolaryngologist and neurosurgeon is necessary, thereby improving operating room workflow and time management. A series of 10 patients is presented, showing the feasibility of this procedure and providing operative details that were previously absent in the peer-reviewed literature. CONCLUSIONS: Combined petrosectomy, although often performed in a 3-step manner with the neurosurgeon starting the craniotomy, can be performed as described here in a 2-step manner, with similar outcomes and reasonable operating time.

Transpalpebral transorbital neuroendoscopic (TONES) repair of orbital meningoencephalocele: a technical note.

PURPOSE: Intraorbital encephalocele (OMEC) is a rare entity in adults, usually secondary to an orbital pathology or prior trauma, in particular orbital roof fractures. Treatment of the OMEC is warranted to alleviate the pulsating exophthalmos and prevent potential visual decline. OMEC and orbital roof fractures have been predominantly treated via a craniotomy with a reconstruction of the orbital roof using various implants. With the advances in the endoscopic techniques, neuroendoscopy found its application in the treatment of orbital pathologies. We report a minimally invasive alternative: endoscopic transorbital repair of OMEC. MATERIAL AND METHODS: The repair technique is described with illustrations and clinical images. Narrated operative video demonstrating the procedure is provided. RESULTS: Illustrative case: 50-year-old female presented with progressive right eye proptosis over 6 months. Computed tomography (CT) demonstrated bony erosion in the lateral orbital roof, and magnetic resonance imaging (MRI) showed a small hyperintense T2-weighted and T1-weighted contrast enhancing lesion in the orbit, in the area of the bony erosion. Intraoperatively, the lesion was found to be an orbital encephalocele. The orbital defect was successfully repaired by employing the 'sandwich' technique, in which a dural substitute reinforced with tissue glue were deployed without repair of the osseous orbital roof. The patient tolerated the procedure well with ultimate resolution of proptosis. The cosmetic outcome was excellent. CONCLUSION: The transorbital neuroendoscopic approach (TONES) presents a feasible, minimally invasive alternative treatment option for circumscribed intraorbital encephaloceles with minimal side effects, well tolerated by patients.

Kyphoplasty of C2 Pathological Fractures Using an Anterior Midline Approach and Steerable Osteotome: Technical Note and Case Series.

BACKGROUND: Malignant lesions involving the C2 vertebral body (axis) may be challenging to treat, and not all patients with cancer are good candidates for posterior cervical or occipitocervical instrumentation. OBJECTIVE: To describe a modified technique of the direct anterolateral C2 kyphoplasty using a steerable osteotome, commonly used for the treatment of thoracolumbar spinal lesions. We also report a case series of 11 patients treated with this technique at our institution. METHODS: The authors performed a retrospective review of all patients who underwent a C2 kyphoplasty using the anterior midline approach from 2010 to 2020. Patient demographics, tumor characteristics, pain severity (visual analog scale), Karnofsky performance status , perioperative complications, and postoperative spinal stability were assessed. RESULTS: The main indication for a C2 kyphoplasty was refractory neck pain. All patients tolerated the procedure well. There were no intraoperative complications. One patient developed transient dysphagia. Visual analog scale scores were 9.00 ± 1.10 preoperative and 3.73 ± 1.85 at 2 weeks and 1.67 ± 1.66 at 3 months after the procedure and continued to stay low during the remainder of the follow-up (4-60 months). The Karnofsky performance status improved from 72.73 ± 11.04 preoperatively to 82.22 ± 8.33 at 2 weeks and 86.67 ± 5.00 at 3 months after the procedure. There was no evidence of new occurrence or progression of C2 fractures. CONCLUSION: The anterior kyphoplasty using a steerable osteotome for tumors of the axis can result in lasting pain reduction and improved cervical stability while demonstrating a low complication rate.

Postoperative magnetic resonance imaging signal changes in middle cerebral peduncle after vestibular schwannoma surgery.

BACKGROUND AND PURPOSE: Preoperative compression of middle cerebellar peduncle (MCP) is often observed in vestibular schwannomas. Its re-expansion is expected after tumour resection, however, frequently its thickness remains unchanged or undergoes further atrophy. Similarly, increased MCP FLAIR signal is often observed and thought to be associated with intraoperative MCP injury. This study investigates the dynamics of MCP FLAIR signal changes over time and their implications in long-term MCP atrophy. MATERIALS AND METHODS: Retrospective analysis of patients operated between 2011 and 2019 was performed. Measurements of FLAIR signals and MCP thickness were performed preoperatively, postoperatively and at follow-up. RESULTS: 28 patients (15 females, mean age 51.94 years) were included. The mean follow-up was 23.98 months. The mean tumour size was 2.99 cm. The MCP FLAIR signal was elevated preoperatively in 10 (35.7%) patients and further increased postoperatively in 22 (78.6%), followed by its decrease at follow up (7 patients, 25%). An immediate postoperative re-expansion of middle cerebellar peduncle was observed in 24 (85.7%) patients. No association between tumour size and preoperative FLAIR was established, however tumour size was negatively associated with the MCP thickness. A significant negative association between a postoperative FLAIR and follow-up thickness (p < 0.001) was noted, even if controlling for tumour size and both tumour size and preoperative MCP thickness. CONCLUSION: In patients with vestibular schwannomas undergoing surgical resection, the middle cerebellar peduncle FLAIR signal seems to associated with long term thickness of MCP, regardless of its initial size, however does not seem to correlate with the clinical outcome.

Resection of Giant Remote Recurrence of Ependymoma After 41 Years.

Ependymomas are rare primary tumors of the brain and spinal cord that arises from the ependymal cell layer. Cranial ependymomas commonly occur in the posterior fossa; however, approximately 30% of all tumors can be found in the supratentorial region. Supratentorial ependymomas have a shorter progression-free and overall survival than their infratentorial counterparts. We present the case of a 47-year-old man who presented with mild left-sided hemiparesis and confusion secondary to a right-sided 8.5 × 6.0 × 6.0 cm frontotemporal neoplasm encasing the ipsilateral internal and middle cerebral arteries. The patient had undergone a suboccipital craniectomy for resection of a posterior fossa ependymoma at 6 years of age (41 years ago). After multidisciplinary discussion, we performed a right frontotemporal craniotomy for tumor resection (Video) using intraoperative navigation, ultrasound, and intraoperative neurophysiological monitoring. While skeletonizing branches of the middle cerebral artery, an M3 branch was injured inadvertently and repaired immediately. Histopathologic specimens were consistent with ependymoma (World Health Organization grade II). A near-total resection was achieved. The patient developed a transient left-sided hemiparesis but improved to full strength on discharge from the hospital.

The Final Cut: Evolution of Cavernous Sinus Decompression Beyond the Dolenc Cut.

BACKGROUND: Meningiomas involving the cavernous sinus (CS) represent a formidable challenge to neurosurgeons. Because of high morbidity, aggressive tumor resection within the CS has been largely replaced by extracavernous tumor resection and decompression of the CS. The widely used Dolenc method involves blind dural transection over the oculomotor nerve, potentially placing the crossing trochlear nerve at risk. OBJECTIVE: To provide a safer way for the decompression of the CS and at the same time, circumferential resection of the temporal lobe dura. METHODS: Cadaveric dissection of 8 cadaveric heads (16 sides) was performed. Frontotemporal craniotomy with zygomatic osteotomy was performed. Extradural and intradural dissection of the lateral wall of the CS and free edge of tentorium was performed. Photographic documentation, artistic illustrations, and illustrative video cases are provided. RESULTS: Three tether points were released: anterior-the meningo-orbital band, lateral-dura over the V2 and V3, and medial-superficial layer of the free edge of tentorium. Transection of the superficial layer of the free edge of the tentorium along its edge, in conjunction with a lateral cut over the temporal convexity, constitutes the final cut, allowing a resection of the lateral CS wall and the circumferential resection of temporal lobe dura. CONCLUSION: Using the "final cut" technique allows for a circumferential resection of the temporal lobe dura and lateral CS wall while avoiding blind cuts that could put cranial nerves at risk. All dural transections are performed in anatomically separated layers under constant visualization.

Factors associated with in-stent stenosis after cerebral aneurysm embolization using a Pipeline embolization device.

BACKGROUND: Flow-diverting (FD) stents, with or without coiling, are a mainstay in endovascular treatment of intracranial aneurysms (IAs). One observed complication from flow diverter stent (FDS) insertion has been in-stent stenosis. Though previously studied in the short-term period, the long-term history of this complication has yet to be described. METHODS: We performed a retrospective cohort study of consecutive IAs treated with Pipeline Embolization Device (PED), with or without coiling, at our centre between September 2014 and December 2018 that had at least one digital subtraction angiogram (DSA) during follow-up. In-stent stenosis was measured from DSA images, and associated patient and procedural characteristics were analysed. RESULTS: 94 patients treated with PED for IA were identified. On initial DSA during follow-up, 52 patients (55.3%) had in-stent stenosis within the PED. Of these 52 patients, 17 had a second DSA during follow-up. In this 2nd DSA, improvement and/or stable in-stent stenosis was seen 16 patients (94.1%). One patient in this group had worsening in-stent stenosis had a vertebrobasilar junction FD stent. Of the patients without in-stent stenosis on initial DSA, 15 had a second DSA during follow-up. Only one of these patients (6.7%) had new appearance of in-stent stenosis (measuring 5%). Multivariate analysis found statin use to be predictive of in-stent stenosis (p = 0.020, Odds ratio = 0.279 and 95% confidence interval = 0.095-0.821). CONCLUSIONS: In-stent stenosis after FDS placement was seen in 53.2% of cases, which had between 1-50% of stenosis. 82.4% had resolution/improvement of their stenosis. Statin use was protective of in-stent stenosis.

The ventral pathway of the human brain: A continuous association tract system.

The brain hemispheres can be divided into an upper dorsal and a lower ventral system. Each system consists of distinct cortical regions connected via long association tracts. The tracts cross the central sulcus or the limen insulae to connect the frontal lobe with the posterior brain. The dorsal stream is associated with sensorimotor mapping. The ventral stream serves structural analysis and semantics in different domains, as visual, acoustic or space processing. How does the prefrontal cortex, regarded as the platform for the highest level of integration, incorporate information from these different domains? In the current view, the ventral pathway consists of several separate tracts, related to different modalities. Originally the assumption was that the ventral path is a continuum, covering all modalities. The latter would imply a very different anatomical basis for cognitive and clinical models of processing. To further define the ventral connections, we used cutting-edge in vivo global tractography on high-resolution diffusion tensor imaging (DTI) data from 100 normal subjects from the human connectome project and ex vivo preparation of fiber bundles in the extreme capsule of 8 humans using the Klingler technique. Our data showed that ventral stream tracts, traversing through the extreme capsule, form a continuous band of fibers that fan out anteriorly to the prefrontal cortex, and posteriorly to temporal, occipital and parietal cortical regions. Introduction of additional volumes of interest in temporal and occipital lobes differentiated between the inferior fronto-occipital fascicle (IFOF) and uncinate fascicle (UF). Unequivocally, in both experiments, in all subjects a connection between the inferior frontal and middle-to-posterior temporal cortical region, otherwise known as the temporo-frontal extreme capsule fascicle (ECF) from nonhuman primate brain-tracing experiments was identified. In the human brain, this tract connects the language domains of "Broca's area" and "Wernicke's area". The differentiation in the three tracts, IFOF, UF and ECF seems arbitrary, all three pass through the extreme capsule. Our data show that the ventral pathway represents a continuum. The three tracts merge seamlessly and streamlines showed considerable overlap in their anterior and posterior course. Terminal maps identified prefrontal cortex in the frontal lobe and association cortex in temporal, occipital and parietal lobes as streamline endings. This anatomical substrate potentially facilitates the prefrontal cortex to integrate information across different domains and modalities.

Interdisciplinary treatment of posterior fossa dural arteriovenous fistulas.

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.

Contralateral Transfalcine Approach to Deep Parasagittal Arteriovenous Malformations-Technical Note.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.