Faculty Bibliography

Background: The transcochlear approach extends the anterior exposure afforded by the translabyrinthine technique. Although this wider exposure allows improved access to cranial nerves and the brainstem with less retraction on the cerebellum, the classical description involving facial nerve transposition often results in permanent facial paresis. This study discusses the role of the transcochlear approach in resection of cerebellopontine angle tumors including patient selection, surgical technique, and outcomes. Study Design: Retrospective review. Methods: This is a retrospective review conducted at a single academic institution. Cases performed by our skull base team (neurotologist and neurosurgeon) between 2000 and 2015 were reviewed. All cases utilizing the transcochlear approach were included. Factors including tumor size, completeness of resection, facial nerve function, post-operative complications, and length of stay were analyzed. Results: Fourteen cases were included. All of these patients had pre-operative severe hearing loss except for two in which surgery was performed urgently in the setting of hydrocephalus and brainstem compression. Eight out of 14 patients had pre-operative facial paresis. Tumor size ranged from 2.2-7 cm in greatest dimension (mean = 4.56 cm). All patients underwent a transcochlear approach to and removal of tumor with blind sac of the external auditory canal. In addition, 3 patients underwent an immediate facial nerve to hypoglossal anastomosis. Post-operatively, patients remained in the hospital for 3-5 days (mean = 4). Of the patients who started out with normal facial nerve function (n = 6), 3 recovered to House-Brackmann scores II or greater. There were no reported CSF leaks requiring hospitalization and 1 abdominal hematoma from fat graft harvest. There was a single mortality reported in the peri-operative period; however, on autopsy the cause of death was unrelated to the surgery itself or any subsequent intracranial event. Conclusions: As in other surgical approaches destructive to the labyrinth, patients were selected with consideration of their pre-operative hearing status and/or their candidacy for hearing preservation surgery. Patients with pre-operative facial nerve paralysis and hearing loss were deemed particularly appropriate candidates for the transcochlear technique given the additional exposure and the lack of added morbidity. In these cases the surgeon also has the option to perform dynamic facial nerve reanimation at the time of tumor resection

Background: Salvage surgery for progressive symptoms or recurrent growth of vestibular schwannoma (VS) after stereotactic radiosurgery (SRS) is uncommon. It has been reported to be more difficult, the same or easier than expected compared with microsurgical resection (MS) of treatment-naive VS, with variable facial nerve outcomes. We conducted a matched cohort analysis to evaluate facial nerve outcomes for patients undergoing MS for progressive symptoms or recurrent growth of VS after SRS compared with MS for treatment-naive VS. Methods: We evaluated the records of 365 non-NF2 VS patients treated with MS from 2001 to 2014. All patients who had postoperative notes were considered to have "adequate follow-up" and included in the study. Nine patients underwent resection for VS after prior SRS (MS-POST SRS) with no prior intervention, 7 of which had adequate follow-up, and 331 patients that underwent MS for treatment naive VS (MS-NO SRS), 317 of which had adequate follow-up. From this dataset, we created propensity score matched cohorts to retrospectively compare facial nerve preservation and clinical outcomes. The propensity score model incorporated age at surgery, tumor size, and pre-operative HB grade, and cases were matched at a ratio of 4:1 MS-NO SRS to MS-POST SRS cases. Results: The MS-POST SRS (n = 7) and MS-NO SRS (n = 28) groups differed only in preoperative hearing status (p < 0.01). Preoperative HB grades were similar between MS-POST SRS and MS-NO SRS groups (p>0.3). The average time-to-intervention after SRS in the MS-POST SRS group was 44.4 months. The indication for MS after SRS was symptom progression with tumor growth in 4 cases, and only tumor growth in the remaining 3. Postoperatively, 3 cases in the MS-POST SRS group demonstrated improvement in HB grade and none became worse whereas 3 of 28 cases in the MS-NO SRS group demonstrated improvement and 12 cases had decrement in HB grade relative to baseline (p < 0.05). There was no significant difference in the extent of resection with both cohorts (MS-POST SRS and MS-NO SRS) attaining gross total resection in 85.7% of cases. Subsequent intervention was not required for any case in the MS-POST SRS group and 2 cases in the MS-NO SRS group, although this difference was not significant. Both cases requiring subsequent intervention in the MS-POST SRS group were gross total resections via the translabyrinthine approach, with subsequent intervention required at 62 and 48 months. There were no significant differences in the complication rate for individual complications or the overall complication rate between cohorts. Conclusions: At a center with high clinical volume, microsurgical resection of VS after prior SRS was associated with good postoperative facial nerve preservation and low morbidity, comparable to those observed in resection of treatment-naive VS. In addition there were similar outcomes in terms of extent of resection between the two groups. The good outcomes reported here may reflect a confluence of factors which include patient selection, the experience of the attending surgeons, the use of more contemporary SRS dosing protocols during initial treatment for these patients, and divergent goals of therapy between cohorts

Objective: Cerebral venous sinus thrombosis (CVST) is a rare but potentially dangerous complication following craniotomies involving the posterior fossa, the skull base, and craniotomies involving the superior sagittal sinus. Surgical manipulation of the sinuses has been shown to cause sinus thromboses of varying degrees. This phenomenon is often clinically silent, with only a small number of patients becoming symptomatic. Recent advances in neuroimaging provide higher resolution evaluation of cerebral sinuses pre and postoperatively, often revealing clinically silent filling defects. Although sinus thrombosis can be a major cause of morbidity and mortality, its incidence and factors that contribute to its formation in the postoperative population remain unclear. In addition, current guidelines advise to anticoagulate with Heparin upon diagnosis, which can be contraindicated for immediate post craniotomy patients. The goal of this study is to evaluate retrospective data of patient outcomes and factors that might contribute to sinus thrombus formation. Methods: A retrospective chart review was conducted at NYU Langone Medical Center. Ninety-seven patients were included who underwent either a retrosigmoid/translabrynthine/suboccipital resection of a posterior fossa tumor or a supratentorial craniotomy for resection of parasagittal/falcine tumor between July 1, 2014 and July 1, 2015. Pre operative Magnetic Resonance Venography (MRV) was obtained per the attending surgeon's discretion. Based on intraoperative findings, clinical symptoms, and surgeon's preference, a postoperative MRV was obtained. Decision to treat a thrombosis was made based on the results of the MRV and clinical symptoms. Treatments included observation, intravenous fluids (IVF) alone, anti-platelet therapy with Aspirin alone, or a combination of the two. Results: A total of 7 of 97 patients (7.22%) had postoperative sinus thrombosis. Of those patients, 5 had occlusion of the venous sinuses. In the occlusion group, 4 had preoperative imaging documenting patency of the sinuses. An additional 2 patients had postoperative MRVs revealing partial thrombosis of the sinus, 1 that was new and 1 that did not have a preoperative MRV for comparison. Compared with the cohort of patients without postoperative thromboses, there was no significant difference in age, BMI, length of surgery, or surgical approach. Of the 5 patients with postoperative thrombotic occlusion, 4 underwent intervention (1 with IVF alone, 2 with IVF and aspirin, and 1 with aspirin alone). Two patients with thromboses also developed CSF leaks requiring lumbar drainage and operative repair. One patient had a persistent CSF leak requiring a shunt. Of the 2 patients with partial thrombosis, 1 was placed on IVF and aspirin. At 3 months follow up, 1 out of 5 patients in the occlusion group had recanalization of the previously thrombosed sinus. Conclusions: MRV is a non-invasive method to evaluate the caliber and patency of dural venous sinuses in post craniotomy patients. Symptomatic thrombosis is rare and can be managed either conservatively or with IVF and/or anti platelet therapy, both which are safer than anticoagulation with heparin in post craniotomy patients. A larger prospective trial is necessary to further characterize the incidence of postoperative venous sinus thrombosis, identify risk factors, and to devise recommendations for therapy

OBJECTIVE: Dose-response relationships for meningioma radiosurgery are poorly characterized. We evaluated determinants of local recurrence for meningiomas treated with Gamma Knife radiosurgery (GKRS), to guide future treatment approaches to optimize tumor control. MATERIALS AND METHODS: A total of 101 consecutive patients (108 tumors) who underwent GKRS for benign, atypical, or malignant meningiomas between 1998 and 2011 were studied. Local recurrence was assessed. Cox proportional hazards and logistic regression analyses were used to determine the association of patient-related, tumor-related, and treatment-related characteristics with local recurrence. Acute and late toxicity was evaluated. RESULTS: World Health Organization (2007 classification) tumor grade was I (82%), II (11%), or III (7%). Median dose was 14 Gy (range, 10 to 18 Gy) for grade I tumors and 16 Gy (range, 12 to 20 Gy) for grade II and III tumors. Median follow-up was 25 months (maximum, 17 y). Two- /5-year actuarial local control rates were 100%/98% for grade I tumors and 76%/56% for grade II/III tumors. Higher tumor grade and lower GKRS dose were associated with local failure. In this cohort, there was a 42% relative reduction in local recurrence for each 1 Gy of dose escalation. CONCLUSIONS: Treatment was well tolerated with no moderate or severe toxicity. Tumor control was excellent in benign tumors and suboptimal in higher grade tumors. Because the main determinant of local recurrence was GKRS dose, we recommend dose escalation for atypical or malignant tumors to doses between 16 and 20 Gy where critical structures allow.