Application of Topographical Anatomy of the Trochlear Nerve in Transtentorial Approaches: An Anatomic Study.

BACKGROUND AND OBJECTIVES: Transection of the free edge of tentorium (FET) might be necessary when approaching cavernous sinus lesions, clip placement in certain posterior communicating artery aneurysms, or during transpetrosal and retrosigmoid transtentorial approaches. No anatomic study has investigated the relationship of the trochlear and oculomotor nerve and FET in an attempt to identify a safe zone for such maneuver. METHODS: Ten embalmed specimens (20 sides) were studied and the following morphometric measurements were taken using digital microcalipers: trochlear (TP) to oculomotor porus (OP), length of the intratentorial segment of cranial nerve (CN) IV, nerve free FET, and distance along the oculomotor (CN III) from its OP to CN III/trochlear (CN IV) crossing and angle between the long-axis petrous ridge and TP (petrotrochlear angle). RESULTS: The CN IV pierced the deep layer of the FET in all cases at a mean distance 8.11 mm (4.43-11.33) posterior to the OP, measured along the FET. CN IV continued within the tentorial edge for a mean of 6.17 mm (3.18-11.33) before entering the cavernous sinus at a mean distance of 1.9 mm (0-5.46 mm) from the posterior-most aspect of the OP. A nerve-free portion of FET was 1.93 mm (mean) (0-5.46). No nerve-free FET segment (<1 mm) was observed in 4 sides (20%), and a nerve-free FET segment <2.00 mm was seen in 55% of cases. The mean distance from OP to the CN III/IV crossing was 10.17 mm (1.00-15.57). The mean petrotrochlear angle was 164.49° (140.01-183.85), and >175° in 4 specimens (20%). CONCLUSION: Our data confirm presence of the intratentorial segment of CN IV. Transection of the FET carries the lowest risk of CN IV injury if performed < 2 mm or >10 mm posterior to the OP, or posterior to intersection of the FET and a virtual extension of a petrous ridge.

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.

Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies.

BACKGROUND AND OBJECTIVES: Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy. METHODS: A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella-sphenoid angle (a representation of the coronal slope of FO). Mann-Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation. RESULTS: Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella-sphenoid angles (median = 52.00° vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically. CONCLUSION: We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

Significant tumor compression of the middle cerebellar peduncle is associated with worse facial nerve outcomes and lower extent of resection in surgery for medium-sized vestibular schwannomas - A radiographic analysis of a case series.

BACKGROUND AND OBJECTIVE: Optimizing the extent of resection (EOR) and facial nerve outcomes (FNO) remain a challenge in medium to large vestibular schwannomas (VS). Currently, tumor size has been the only consistently reported factor predicting FNO and EOR. Here, we sought to evaluate whether the degree of the tumor's compression on the middle cerebellar peduncle (PC) influences FNO and EOR in medium to large VS. METHODS: This retrospective case series included 99 patients who underwent surgical resection of their VSs from 2014 to 2022. Preoperative MR imaging was used to measure the degree of PC. Patient medical records were queried to determine the EOR and FNO. RESULTS: Patients with unfavorable FNO (HB 3 +) immediately post-op had significantly greater PC than those with favorable FNO (19.9 vs. 15.4 mm, P = .047). This significance was not observed at the last follow-up but there was a trend. When medium-sized tumors (15-30 mm) were analyzed separately, patients with unfavorable FNO immediate post-op and at last follow-up had significantly greater PC than their favorable counterparts (14.1 vs 8.7 mm). Significantly greater PC was also observed in patients who underwent subtotal resection (20.7 mm) compared to near (14.3 mm) and gross total resection (10.8 mm). Multivariate analyses confirmed these findings in medium-sized tumors, but not large-sized tumors. CONCLUSION: The degree of PC as measured on preoperative imaging can predict FNO and EOR in medium-sized vestibular schwannomas. Medium-sized tumors with > 15 mm of PC likely will have worse FNO and lower EOR.

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.

Does Head Positioning After Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Matter?

BACKGROUND: Percutaneous glycerol rhizotomy (PGR) is a minimally invasive procedure for patients with trigeminal neuralgia who are not candidates for microvascular decompression. PGR has widely varying success rates. It has been postulated that differences in post-injection head positioning might account for the various success rates. METHODS: By comparing glycerol dispersion after injection at various head positions, we provide the first evidence supporting post-injection head flexion positioning. Furthermore, we study the clival-Meckel cave (CMC) angle as a predictor of beneficial glycerol flow, measured on computed tomography images. Twenty-two dissected cadaveric specimens were injected with dyed glycerol through the Hartel approach. The glycerol dispersion was measured at prespecified intervals for 1 hour. The Mann-Whitney U and χ2 tests were used to determine the most ideal angle of head flexion to avoid posterior glycerol dispersion and ensure V1-V3 branch glycerol submersion. RESULTS: We found that 30° of anterior head flexion provided optimal trigeminal nerve glycerol submersion (81.82%) in comparison to neutral (27.27%) and 15° (68.18%), P < 0.001. There was minimal unfavorable dispersion beyond 30 minutes at all angles. More obtuse CMC angles were associated with higher rates of unfavorable BC dispersion (U = 6.0; P = 0.001). For specimens with CMC angles >75°, unfavorable BC dispersion was prevented by head flexion (U = 4.5; P = 0.021). We show that 30° of lateral head tilt achieves V1 submersion in all specimens by 30 minutes [X2(1,N = 44) = 22.759; P < 0.001]. CONCLUSIONS: We found that 30° anterior head flexion for >30 minutes provides ideal conditions for PGR to avoid BC dispersion and ensure V1-V3 branches achieve glycerol submersion. For patients with V1 symptoms, contralateral head flexion might help optimize treatment effects.

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.

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.

Outcomes of Arterial Bypass for Posterior Circulation Atherosclerosis: A Case Series.

BACKGROUND: Extracranial-intracranial bypass is an effective treatment option for moyamoya disease and in well-selected cases of anterior circulation intracranial atherosclerotic disease; however, the effectiveness of bypass is less evident in posterior circulation atherosclerosis. Updated surgical techniques and clinical guidelines necessitate modern appraisal of arterial bypass for symptomatic patients with posterior circulation atherosclerotic disease who are refractory to medical management. OBJECTIVE: To evaluate the complications, graft patency, and postoperative outcomes of arterial bypass for posterior circulation intracranial atherosclerotic disease. METHODS: Perioperative records of consecutive bypass patients were retrospectively evaluated to determine the clinical course and surgical outcomes. RESULTS: Arterial bypass was performed in 8 cases with a median age of 62 years. All 8 patients underwent direct bypass with an autologous occipital artery donor vessel. Recipient vessel selection varied on a case-by-case basis, with the superior cerebellar artery used in 4 cases, the posterior inferior cerebellar artery in 3 cases, and the anterior inferior cerebellar artery in 1 case. There were no significant intraoperative or postoperative complications. Postoperatively, all 8 patients displayed clinical improvement of their preoperative symptoms, with a significant decrease of 2.5 points on the modified Rankin Scale (P < .001). Postoperative imaging confirmed full graft patency in 7 patients and partial patency in 1 patient. CONCLUSION: Excellent postoperative outcomes and no major complications after posterior circulation arterial bypass for intracranial atherosclerotic disease highlight the utility of this intervention for the treatment of medically refractory or symptomatic posterior circulation intracranial atherosclerotic disease. Larger studies may be valuable to validate these findings.

Robotic Arm-Protected Microsurgical Pericallosal and Middle Cerebral Artery Aneurysm Clipping: A Technical Note and Case Series.

BACKGROUND: Managing intraoperative aneurysm rupture (IAR) during intracranial aneurysm clipping can be challenging given the excessive hemorrhage and limited field of view under the microscope for visualizing the proximal artery and safe temporary clipping. OBJECTIVE: To describe the first known use of robotic arm for safeguarding IAR in microsurgical aneurysm clipping. METHODS: A robotic arm was used to safeguard 3 microsurgical clipping cases (1 pericallosal and 2 middle cerebral artery) performed by a single surgeon. The device was installed onto the side rail of the operating table along with the clip applier attachment. After dissecting the cerebral artery segment proximal to the aneurysm, a temporary aneurysm clip was loaded and established at the appropriate segment before dissecting distally toward the aneurysm. RESULTS: Setup for the robotic arm and temporary clip was simple, quick, precise, and without any unforeseen accommodations needed in all 3 instances. The temporary clip acted as an emergency gate and could be deployed either manually or remotely through a controller. IAR occurred in case 1, and the robotic-assisted temporary clip deployment achieved immediate hemostasis without complications. This method bypassed the need for significant suctioning, packing, and further exploration for safe temporary clipping. Case 2 and 3 demonstrated the feasibility for middle cerebral artery protection and ease of intraoperative readjustment. CONCLUSION: This technical note highlights the feasibility and relative ease of using a robotic arm as a safeguard device, and it enables on-demand control of proximal blood flow and may enhance the safety of microsurgical aneurysm procedures.

Transcarotid artery revascularization (TCAR) stenting or angioplasty for intracranial carotid artery stenosis: Case series and novel application.

BACKGROUND: Carotid artery stenting is associated with a higher rate of stroke compared to carotid endarterectomy (CEA). This is likely due to procedural emboli resulting from plaque disruption. The transcarotid artery revascularization (TCAR) method aims to reduce the stroke rate by flow-reversal. TCAR, which has yet to be utilized for intracranial atherosclerotic disease (ICAD), may be particularly valuable given the lack of surgical treatment options for intracranial arterial stenosis. OBJECTIVE: Presented here are five cases of angioplasty or stenting that demonstrate the feasibility of TCAR for intracranial Internal Carotid Artery (ICA) stenosis treatment. METHODS: Five cases were reviewed retrospectively and summarized using PROCESS and CARE guidelines. RESULTS: All patients who underwent intervention between the petrous and ophthalmic segment of the ICA had no new neurologic deficit nor detected embolic stroke. One patient experienced an asymptomatic 5 mm hemorrhage on postoperative routine Computed Tomography (CT) head imaging. CONCLUSIONS: This highlights a new method for treating intracranial ICA stenosis with a potentially reduced stroke risk. Given the historically higher stroke rates for cervical ICA stenting compared to carotid artery endarterectomy, this method may improve the previously higher stroke rates in endovascular carotid artery treatment, compared to CEA. Although this series is small, it illustrates a novel use for a rising technique that should be further evaluated in a larger study to validate its efficacy as a new treatment modality for surgically inaccessible intracranial disease.

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.

Modern Appraisal of Patency and Complications in Cerebral Bypass Surgery: A Single Institution Experience.

BACKGROUND: Cerebral bypass is a valuable surgical technique in well-selected patient populations. Updated clinical guidelines and improved surgical techniques warrant a contemporary reevaluation of the complications and patency to inform clinical practice and enhance postoperative patient care. OBJECTIVE: To assess the complication rates and postoperative graft patency for the 3 most common indications for bypass surgery: moyamoya disease, intracranial atherosclerosis, and intracranial aneurysms. METHODS: Perioperative notes of 175 consecutive bypass patients at a single institution were retrospectively identified to evaluate the clinical course and complications of surgery. RESULTS: The rate of total postoperative complications between moyamoya disease (9 of 98, 9.2%), intracranial atherosclerotic disease (7 of 57, 12.3%), and intracranial aneurysm (4 of 20, 20%) was not statistically different (P = .33). Immediate postoperative bypass patency was significantly higher in moyamoya disease (90 of 96, 93.8%) and intracranial atherosclerotic disease (48 of 51, 94.1%) than in intracranial aneurysm (13 of 18, 72.2%; P = .02). Intravenous heparin administration during bypass suturing was negatively associated with immediate postoperative patency (87% heparin patency vs 99% no heparin patency; P = .02). Double-barrel bypass trended toward an increased risk of wound healing complications (2 of 13, 15.4%) compared with the single-barrel bypass technique (4 of 156, 2.6%; P = .07). CONCLUSION: Cerebral bypass surgery remains an excellent surgical treatment for moyamoya disease, intracranial atherosclerosis, and intracranial aneurysms. This study suggests bypass is safer in moyamoya disease and intracranial atherosclerosis. Additional studies to clarify the risk of single-barrel vs double-barrel bypass and intraoperative heparin-stratified complications may be beneficial.

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.

Changing Enhancement Pattern and Tumor Volume of Vestibular Schwannomas After Subtotal Resection.

BACKGROUND: Surgical strategy in vestibular schwannomas may require subtotal resection to preserve neurologic function. Residual tumor growth pattern and contrast enhancement in the immediate postresection period remain uncertain. We sought to evaluate changes in the enhancement pattern and volume of vestibular schwannomas after subtotal resection in the immediate postoperative period. METHODS: Volumetric analysis of tumor size and enhancement patterns of vestibular schwannomas were measured on magnetic resonance imaging (MRI) scans obtained within 3 days of surgery, 3 months after surgery, and 1 year after surgery. RESULTS: Nineteen patients were eligible for inclusion in the study (9 male and 10 female) with an average age of 47 years. Contrast enhancement was absent in 6 of 19 (32%) of cases on the immediate postresection MRI with return of expected enhancement on subsequent studies. Volumetric analysis identified that tumors decreased in size by an average of 35% in the first 3 months (P = 0.025) after resection and 46% in the first year after resection (P < 0.01). CONCLUSIONS: Vestibular schwannomas that undergo subtotal resection tend to decrease in size over the first 3 months after resection. Residual tumor volume may fail to enhance on the immediate postresection MRI. Both of these findings could lead surgeons to misinterpret degree of resection after surgery and have implications for clinical decision making and research reporting in the scientific literature for vestibular schwannomas after subtotal resection.

Retrosigmoid Transtentorial Approach Compared to Traditional Transpetrosal Approaches for the Resection of Petroclival Meningiomas: A Case-Control Study.

Background Transpetrosal approaches have become standard technique for resection of petroclival meningiomas (PCM). The retrosigmoid craniotomy has also been extensively studied as an alternative approach. The need to resect the tentorium at the end of a retrosigmoid approach has been described, but the upfront transtentorial variation of the retrosigmoid craniotomy has never been described nor evaluated in detail as a possible alternative to the standard petrosectomy approaches. Objective This study was aimed to directly compare the transpetrosal approaches to the retrosigmoid transtentorial approach (RSTTA) in terms of degree of resection, duration of surgery, and estimated blood loss (EBL). Methods A retrospective case-control study of patients who underwent resection of PCM between January 2014 and December 2018 was performed. Patients in the two surgical approach groups were matched for age and tumor location. The primary measured outcomes were duration of surgery, EBL, extent of resection, length of postoperative hospital stay, and complications. Data analysis was performed using analysis of variance (ANOVA), multivariate analysis of variance (MANOVA), and analysis of covariance (ANCOVA) tests. Results Thirteen patients had microsurgical resection of PCM at our center between January 2014 and December 2018. Nine patients underwent a transpetrosal approach and four patients underwent RSTTA. The average duration of surgery was shorter in the RSTTA group (425 vs. 525.4 minutes) and had less blood loss (94 vs. 425 mL). Extent of resection was comparable between the groups. Conclusion The RSTTA appears to be a safe and efficient technique for resecting PCMs and in selected cases a valid alternative to standard petrosectomies approaches.

Teflon versus Ivalon in Microvascular Decompression for Trigeminal Neuralgia: A 2-Center 10-Year Comparison.

BACKGROUND: Trigeminal neuralgia features jolts of pain along the distribution of the trigeminal nerve. If patients fail conservative management, microvascular decompression (MVD) is typically the next step in treatment. MVD consists of implanting a separating material, often Teflon, between the nerve and compressive lesions. A review found similar success and complication rates between Teflon and Ivalon, another commonly used material. The aim of this study was to analyze outcomes and complications associated with Teflon and Ivalon in MVD. METHODS: We conducted a 2-center retrospective cohort study of trigeminal neuralgia treated with MVD between 2005 and 2019. Patients with no postoperative follow-up were excluded. Postoperative pain was graded using the Barrow Neurological Institute (BNI) pain intensity score. Relapse was defined as a BNI score of 4-5 during follow-up after initial pain improvement or an initial BNI score of 1-3. RESULTS: The study included 221 MVD procedures in 219 patients. Ivalon was implanted in 121 procedures, and Teflon was implanted in 100 procedures. Multivariate analysis found that implant type had no effect on final BNI score (P = 0.305). Relapse rates were similar at 5- and 10-year follow-up (5-year: Ivalon 10.7%, Teflon 18.0%, P = 0.112; 10-year: Ivalon 11.6%, Teflon 19.0%, P = 0.123). There was no difference in postoperative immediate facial numbness (P = 0.125). Postoperative hearing difficulty was higher in the Ivalon cohort (8.4% vs. 1.0%; P = 0.016). CONCLUSIONS: We found no significant difference in final BNI score or risk of relapse between Ivalon and Teflon. Complications were similar, although Ivalon was more associated with temporary postoperative hearing loss.

The Return Back to Typical Practice from the "Battle Plan" of the Coronavirus Disease 2019 (COVID-19) Pandemic: A Comparative Study.

BACKGROUND: Every aspect of the medical field has been heavily affected by the coronavirus disease 2019 (COVID-19) pandemic, and neurosurgical services are no exception. Several departments have reported their experiences and protocols to provide insights for others impacted. The goals of this study are to report the load and variety of neurosurgical cases and clinic visits after discontinuing the COVID-19 Battle Plan at an academic tertiary care referral center to provide insights for other departments going through the same transition. METHODS: The clinical data of all patients who underwent a neurosurgical intervention between May 4, 2020, and June 4, 2020 were obtained from a prospectively maintained database. Data of the control group were retrospectively collected from the medical records to compare the types of surgeries/interventions and clinic visits performed by the same neurosurgical service before the COVID-19 pandemic started. RESULTS: One hundred sixty-one patients underwent neurosurgical interventions, and seven-hundred one patients were seen in clinic appointments, in the 4-week period following easing back from our COVID-19 "Battle Plan." Discontinuing the "Battle Plan" resulted in increases in case load to above-average practice after a week but a continued decrease in clinic appointments throughout the 4 weeks compared with average practice. CONCLUSIONS: As policy-shaping crises like pandemics abate, easing back to "typical" practice can be completed effectively by appropriately allocating resources. This can be accomplished by anticipating increases in neurosurgical volume, specifically in the functional/epilepsy and brain tumor subspecialties, as well as continued decreases in neurosurgical clinic volume, specifically in elective spine.