Faculty Bibliography

INTRODUCTION: It is known that physicians sometimes recommend treatment that, in a similar clinical scenario, they might not choose for themselves. We sought to understand this dynamic across cerebrovascular practice and examine how neurosurgeons value the procedures they offer. METHODS: We conducted an online survey sent to a large cohort of neurosurgeons in May 2013. Respondents were randomised to answer either as the surgeon or as the patient. The questions involved patients presenting with 1) an epidural hematoma (control), 2) un-ruptured anterior communicating artery aneurysm, 3) incidentally found right temporal AVM, 4) spontaneous intracranial and intraventricular haemorrhage in deep structure. Data on practice parameters and experience levels was also collected. RESULTS: We obtained 534 survey responses, 279 responding as the "neurosurgeon", and 255 as the "patient," with a response rate of 19.7%. Demographics amongst the two groups of survey takers was similar. There was no difference in the management of an epidural hematoma, as expected. For the unruptured aneurysm, the rates of opting for treatment was similar amongst respondees. However within the treatment group there was a trend for survey takers to more often chose coiling for themselves and clipping for patients (p = 0.056). Surgeons, however, with a greater than 30% open-cerebrovascular practice had less of a tendency to do so. For arteriovenous malformation management, there was no statistical difference between choosing treatment or conservative management. However, amongst the respondees who chose treatment, more respondees chose resection/embolization for their patient but radiosurgery for self (p = 0.001). In a case of a large spontaneous intracranial and intraventricular haemorrhage neurosurgeons were more likely to place a ventricular drain in a patient than himself or herself. Neurosurgeons in practice more than 10 years since residency were more likely to recommend against interventions for aneurysms, AVMs or intracranial haemorrhage. CONCLUSIONS: In the majority of cases altering the role of the surgeon did not change the decision to pursue treatment or conservative treatment. In certain clinical scenarios, however, neurosurgeons choose treatment options for themselves that are different than what they would choose for their patients. For the management of an arteriovenous malformations, intracranial aneurysms, and hypertensive haemorrhage, responses favored less invasive interventions when the surgeon was the patient. These findings are likely a result of cognitive biases, previous training, experience, areas of expertise, and personal values. DISCLOSURES: O. Tanweer: None. T. Wilson: None. S. Kalhorn: None. J. Golfinos: None. P. Huang: None. D. Kondziolka: None.

Humans have the capacity to evaluate the success of cognitive processes, known as metacognition. Convergent evidence supports a role for anterior prefrontal cortex in metacognitive judgements of perceptual processes. However, it is unknown whether metacognition is a global phenomenon, with anterior prefrontal cortex supporting metacognition across domains, or whether it relies on domain-specific neural substrates. To address this question, we measured metacognitive accuracy in patients with lesions to anterior prefrontal cortex (n = 7) in two distinct domains, perception and memory, by assessing the correspondence between objective performance and subjective ratings of performance. Despite performing equivalently to a comparison group with temporal lobe lesions (n = 11) and healthy controls (n = 19), patients with lesions to the anterior prefrontal cortex showed a selective deficit in perceptual metacognitive accuracy (meta-d'/d', 95% confidence interval 0.28-0.64). Crucially, however, the anterior prefrontal cortex lesion group's metacognitive accuracy on an equivalent memory task remained unimpaired (meta-d'/d', 95% confidence interval 0.78-1.29). Metacognitive accuracy in the temporal lobe group was intact in both domains. Our results support a causal role for anterior prefrontal cortex in perceptual metacognition, and indicate that the neural architecture of metacognition, while often considered global and domain-general, comprises domain-specific components that may be differentially affected by neurological insult.

Background Activation of the mammalian target of rapamycin (mTOR) signaling pathway is thought to be a key driver of tumor growth in Merlin (NF2)-deficient tumors. Everolimus is an oral inhibitor of mTOR complex 1 (mTORC1) with antitumor activity in a variety of cancers. Methods We conducted a single-institution, prospective, 2-stage, open-label phase II study to estimate the response rate to everolimus in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Ten eligible patients were enrolled, including 2 pediatric patients. Everolimus was administered at a daily dose of 10 mg (adults) or 5 mg/m(2)/day (children <18 y) orally in continuous 28-day courses, for up to 12 courses. Response was assessed every 3 months with MRI, using 3-dimensional volumetric tumor analysis, and audiograms. Nine patients were evaluable for the primary response, defined as >/=15% decrease in VS volume. Hearing response was evaluable as a secondary endpoint in 8 patients. Results None of the 9 patients with evaluable disease experienced a clinical or MRI response. No objective imaging or hearing responses were observed in stage 1 of the trial, and the study was closed according to predefined stopping rules. Conclusion Everolimus is ineffective for the treatment of progressive VS in NF2 patients. We are currently conducting a pharmacokinetic/pharmacodynamic ("phase 0") study of everolimus in presurgical VS patients to elucidate the biological basis for apparent treatment resistance to mTORC1 inhibition in these tumors.

HER2-positive breast cancer is a known risk factor for CNS metastases, and the use of trastuzumab in the adjuvant setting does not prevent brain metastases. The purpose of this study is to compare outcomes in HER2-positive and HER2-negative intracranial disease treated with stereotactic radiosurgery (SRS). Among 57 breast cancer patients with brain metastases, 28 patients were HER2-positive. All patients were treated with SRS as their first treatment modality for CNS metastases. The median dose was 20 Gy (range 12-20 Gy). Statistical analysis was performed using the Kaplan-Meier method and chi (2) test. With a median follow-up of 11.0 months, the median time to progression in the HER2-positive group compared with the HER2-negative group was 7 versus 11 months (p = 0.080), respectively. Salvage therapy was performed in 50 % of HER2-positive patients compared with 21 % of HER2-negative patients (p = 0.02). The median OS for the HER2-positive group compared with the HER2-negative group was 22 versus 12 months (p = 0.053). Stereotactic radiosurgery results in excellent local control in the treatment for breast cancer brain metastases. Compared with HER2-negative disease, HER2-positive disease appears to show higher rates of intracranial relapse despite better overall survival rates. This data suggests that we need effective adjuvant therapy to prevent and treat brain metastases in HER2-positive patients.

Endoscopic endonasal surgery has been established as the safest approach to pituitary tumors, yet its role in other common skull base lesions has not been established. To answer this question, we carried out a systematic review of reported series of open and endoscopic endonasal approaches to four major skull base tumors: olfactory groove meningiomas (OGM), tuberculum sellae meningiomas (TSM), craniopharyngiomas (CRA), and clival chordomas (CHO). Data from 162 studies containing 5,701 patients were combined and compared for differences in perioperative mortality, gross total resection (GTR), cerebrospinal fluid (CSF) leak, neurological morbidity, post-operative visual function, post-operative anosmia, post-operative diabetes insipidus (DI), and post-operative obesity/hyperphagia. Weighted average rates for each outcome were calculated using relative study size. Our findings indicate similar rates of GTR and perioperative mortality between open and endoscopic approaches for all tumor types. CSF leak was increased after endoscopic surgery. Visual function symptoms were more likely to improve after endoscopic surgery for TSM, CRA, and CHO. Post-operative DI and obesity/hyperphagia were significantly increased after open resection in CRA. Recurrence rates per 1,000 patient-years of follow-up were higher in endoscopy for OGM, TSM, and CHO. Trends for open and endoscopic surgery suggested modest improvement in all outcomes over time. Our observations suggest that endonasal endoscopy is a safe alternative to craniotomy and may be preferred for certain tumor types. However, endoscopic surgery is associated with higher rates of CSF leak, and possibly increased recurrence rates. Prospective study with long-term follow-up is required to verify these preliminary observations.

Background: Invasion is a dominant escape mechanism following angiogenic blockade in glioblastomas (GBM). Lithium has shown anti-invasive activity in glioma cells by inhibiting Glycogen Synthetase Kinase -3. This phase II study evaluated the safety and efficacy of using lithium and bevacizumab (BEV) in newly diagnosed GBM. Methods: From 2010 through 2012, 20 GBM patients with residual disease after surgery were treated with involved-field radiation therapy to 5940 cGy and concomitant temozolomide (TMZ) (75 mg/m2 daily for 42 days) along with BEV (10 mg/kg every 2 weeks), starting 29 days after surgery. This was followed by six 28-day cycles of TMZ (150 mg/m2 on days 1-7, BEV (10 mg/kg) on days 8 and 22, and lithium 300 mg BID. Lithium was increased every 7 days up to 600 mg BID with a serum lithium goal level of 0.8 to 1.2 mEq/L. Results: The median follow-up was 9.9 months (range 1.9-24.5). Fourteen patients (70.0%) received at least one dose of lithium and three patients completed the entire course of therapy. The median number of BEV infusion was 9 (range 2-19). Five patients discontinued trial due to skin sensitivity (n = 2), pulmonary embolism (n = 1), infection (n = 1), and hematological toxicity (n=1). Two patients experienced dose limiting lithium toxicity which included drowsiness (n = 1) and tremor (n = 1). No patients experienced grade 3/4 intra-cranial hemorrhage. The median progression free survival (PFS) was 9.3 months. The 12-month PFS and OS were 31.9% and 59.3% respectively. For the 14 patients who received lithium, the 12-month PFS and OS were 42.9% and 69.2% respectively. Conclusions: The strategy of targeting angiogenesis and invasion simultaneously in newly diagnosed GBM is effective and feasible

Brain metastases in malignant melanoma carries a poor prognosis with minimal response to any therapy. The purpose of this pilot analysis was to find the effectiveness of vemurafenib, an oral BRAF inhibitor, and radiation therapy in V600 mutated melanoma with brain metastases. BRAF mutation status of the melanoma patients was determined by real-time PCR assay. Retrospective analysis was performed on twelve patients who had the mutation and were treated with either stereotactic radiosurgery or whole brain radiation therapy prior to or along with vemurafenib at a dose of 960 mg orally twice a day. Clinical and radiological responses, development of new brain metastases, overall survival and toxicity were assessed. Improvement in neurological symptoms was seen in 7/11 (64 %) following therapy. Radiographic responses were noted in 36/48 (75 %) of index lesions with 23 (48 %) complete responses and 13 (27 %) partial responses. Six month local control, freedom from new brain metastases and overall survival were 75, 57 and 92 %. Four patients had intra-tumoral bleed prior to therapy and two patients developed steroid dependence. One patient experienced radiation necrosis. This retrospective study suggests that melanoma patients with brain metastases harboring BRAF mutation appear to be a distinct sub-group with a favorable response to vemurafenib and radiation therapy and acceptable morbidity.