Microsurgical Management of Vestibular Schwannoma (Acoustic Neuroma): Facial Nerve Outcomes, Radiographic Analysis, Complications, and Long-Term Follow-Up in a Series of 420 Surgeries.

OBJECTIVE: The purpose of this study is to retrospectively evaluate the clinical and surgical outcomes of a large surgical series of vestibular schwannoma from North America over 20 years. METHODS: After institutional review board approval a retrospective review of the senior author's personal case logs to identify patients who had operations for vestibular schwannoma was performed. The clinical notes, operative record, preoperative and postoperative imagings, and long-term clinical follow-up notes were evaluated. RESULTS: A total of 415 patients who underwent 420 surgeries were identified from the years 1998-2021. The average length of follow-up was 3 years and 9 months. Overall, at last follow-up the rate of "good" facial nerve outcomes (House-Brackmann [HB] score I and II) was 86% and "poor" facial nerve outcomes (HB III-VI) was 14%. The amount of cerebellopontine angle extension (P = 0.023), tumor volume (P = 0.015), facial nerve consistency (P < 0.001), preoperative HB score (P < 0.001), and FN stimulation threshold at the end of the procedure (P < 0.001) were correlated to facial nerve function at the last follow-up. CONCLUSIONS: This study represents one of the largest recently reported surgical series of vestibular schwannoma in North American literature with available long term follow-up. Facial nerve outcomes correlated with cerebellopontine angle extension, tumor volume, facial nerve stimulation threshold, facial nerve consistency, preoperative facial nerve function, and history of a prior resection. Tumor recurrence remains significantly higher after subtotal resection. We believe the data supports a continuation of a strategy of general intent of gross total resection, greatly modifiable by intraoperative findings and judgment.

Cavernous Sinus Meningioma: Tumor Decompression for Trigeminal Neuralgia and Anterior Tibial Artery Graft High-Flow Bypass for Brain Ischemia: 2-Dimensional Operative Video.

A 62-yr-old man with left cavernous sinus tumor presented with atypical trigeminal neuralgia refractory to medical treatment. He received Gamma Knife (Elekta) radiation for the tumor. However, the facial pain worsened after radiation. Neuropsychological testing done for memory problems had revealed mild neurocognitive disorder. Neurological examination showed trigeminal distribution numbness and partial abducens nerve paralysis. Imaging revealed an enhancing left cavernous sinus and supra-cavernous mass. Angiography revealed severe stenosis of the left cavernous internal carotid artery (ICA). Computed tomography (CT) perfusion study showed diminished blood flow on the left side, and ischemic changes were seen in fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI). Surgical resection of the tumor was preferred over ablative treatment for trigeminal neuralgia because of its effectiveness in improving cranial nerve (CN) function.1 The patient underwent staged surgeries. In the first stage, the tumor was partially excised with decompression of the trigeminal ganglion and nerve root in the lateral cavernous sinus wall, Meckel's cave. Postoperatively, MR angiography revealed worsening of the left ICA caliber. Therefore, a high-flow bypass from the external carotid artery to the middle cerebral artery (MCA) was performed with an anterior tibial artery graft. The patient recovered initially but developed enterococcus meningitis postoperatively, which was promptly identified and treated with antibiotics. At 1-yr follow-up, the graft was patent, and the patient had significant relief of his facial pain and cognitively improved. This 2-dimensional video demonstrates the technique of partial excision of cavernous sinus meningioma with CN decompression, and the technique of a high-flow bypass from the external carotid artery to M2 MCA segment using an anterior tibial artery graft. The patient gave informed consent for surgery and video recording. All relevant patient identifiers have been removed from the video and accompanying radiology slides.

Use of preoperative FLAIR MRI and ependymal proximity of tumor enhancement as surrogate markers of brain tumor origin.

Neural stem cells proliferate in the subventricular zone and give rise to progeny that differentiate and migrate throughout the brain. We aimed to test the hypothesis that glioma behavior and grade may correlate with the identity of the tumor cell of origin. We evaluated three preoperative radiographic features (fluid attenuated inversion recovery [FLAIR] MRI characteristics, tumor proximity to ventricular ependyma, and subependymal representation) as surrogate markers of tumor origin using a retrospective cohort design. The medical records of 228 patients who underwent surgical resection of a glioma from January 2004 to August 2008 were reviewed. Average patient age was 54.5 years (standard deviation [SD] 15.3) with a male predominance (62.9%). World Health Organization glioma grades amongst the cohort were Grade IV (71.6%), Grade III (21.3%) and Grade II (7.1%). Mean survival was 11.2 months (SD 10.5) with a mean follow up of 12.8 months (SD 11.3). Glioma tumor grade was significantly correlated to FLAIR signal proximity to the ependymal surface (p<0.01) and inversely with proximity of tumor mass to the ependyma (p<0.01). The mean distance of tumor-associated FLAIR signal from the ependymal surface for glioblastoma multiforme (GBM) was 1.2mm (SD 3.3) compared to 4.8 (SD 6.5) for anaplastic astrocytomas and 6.6mm (SD 6.7; p<0.01) for low grade gliomas. Conversely, the mean distance of the enhancing tumor mass from the ependyma for GBM was 7.3mm (SD 9.4), Grade III glioma 2.3mm (SD 4.9), and Grade II glioma 3.8mm (SD 6.8; p<0.05). These findings suggest that higher grade gliomas might arise from less differentiated neuroepithelial cells in the subventricular zone that possess greater migratory potential.