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OBJECTIVE Awake surgery is becoming more standard and widely practiced for neurosurgical cases, including but not limited to brain tumors. The optimal selection of patients who can tolerate awake surgery remains a challenge. The authors performed an updated cohort study, with particular attention to preoperative clinical and imaging characteristics that may have an impact on the viability of awake craniotomy in individual patients. METHODS The authors conducted a single-institution cohort study of 609 awake craniotomies performed in 562 patients. All craniotomies were performed by the same surgeon at Toronto Western Hospital during the period from 2006 to 2018. Analyses of preoperative clinical and imaging characteristics that may have an impact on the viability of awake craniotomy in individual patients were performed. RESULTS Twenty-one patients were recorded as having experienced intraoperative adverse events necessitating deeper sedation, which made the surgery no longer “awake.” In 2 of these patients, conversion to general anesthesia was performed. The adverse events included emotional intolerance of awake surgery (n = 13), air embolism (n = 3), generalized seizure (n = 4), and unexpected subarachnoid hemorrhage (n = 1). Preoperative cognitive decline, dysphasia, and low performance status, as indicated by the Karnofsky Performance Status (KPS) score, were significantly associated with emotional intolerance on univariate analysis. Only a preoperative KPS score < 70 was significantly associated with this event on multivariate analysis (p = 0.0057). Compared with patients who did not experience intraoperative adverse events, patients who did were more likely to undergo inpatient admission (p = 0.0004 for all cases; p = 0.0036 for cases originally planned as day surgery), longer hospital stay (p < 0.0001), and discharge to a location other than home (p = 0.032). CONCLUSIONS Preoperative physical status was found to be the most decisive factor in predicting whether patients can tolerate an awake craniotomy without complications, whereas older age and history of psychiatric treatment were not necessarily associated with adverse events. Patients who had intraoperative adverse events often had reduced chances of same-day discharge and discharge to home. Preoperative careful selection of patients who are most likely to tolerate the procedure is the key to success for awake surgery.

OBJECTIVECentral nervous system (CNS) germ cell tumors (GCTs) are rare malignant neoplasms that arise predominantly in adolescents and young adults. CNS GCTs demonstrate characteristic trends in national associations, with implications for both tumor incidence and genetics. Although the incidence of CNS GCTs is markedly higher in East Asia than Western countries, direct comparative analyses between these CNS GCT populations are limited.METHODSIn Japan, to facilitate the genomic analyses of CNS GCTs, the Intracranial Germ Cell Tumor Genome Analysis Consortium was established in 2011, and more than 200 cases of GCTs are available for both tumor tissue and clinical data, which is organized by the National Cancer Center (NCC) Japan. At the Mayo Clinic, there have been 98 cases of intracranial GCTs treated by the Department of Neurologic Surgery since 1988. In this paper, the authors compared the epidemiology, clinical presentation including location and histology, and prognosis between cases treated in the US and Japan.RESULTSThere was no significant difference in age and sex distributions between the databases. However, there was a significant difference in the tumor locations; specifically, the frequency of basal ganglia was higher in the NCC database compared with the Mayo Clinic (8.4% vs 0%, p = 0.008), and bifocal location (neurohypophysis and pineal gland) was higher at the Mayo Clinic than at the NCC (18.8% vs 5.8%, p = 0.002). There was no difference in histological subdivisions between the databases. There was no difference in progression-free survival (PFS) and overall survival (OS) of germinoma cases and OS of nongerminomatous GCT (NGGCT) cases treated with chemotherapy and radiation therapy covering whole ventricles. However, PFS of NGGCTs differed significantly, and was better in the NCC cohorts (p = 0.04).CONCLUSIONSThere appears to be a differential distribution of GCTs by neuroanatomical location between major geographic and national groups. Further study is warranted to better characterize any underlying genomic, epigenetic, or environmental factors that may be driving the phenotypic differences.

Glioblastoma (GBM) of the internal auditory canal (IAC) is exceedingly rare, with only 3 prior cases reported in the literature. The authors present the fourth case of cerebellopontine angle (CPA) and IAC GBM, and the first in which the lesion mimicked a vestibular schwannoma (VS) early in its natural history. A 55-year-old man presented with tinnitus, hearing loss, and imbalance. MRI identified a left IAC/CPA lesion measuring 8 mm, most consistent with a benign VS. Over the subsequent 4 months he developed facial weakness. The tumor grew remarkably to 24 mm and surgery was recommended; the main preoperative diagnosis was malignant peripheral nerve sheath tumor (MPNST). Resection proceeded via a translabyrinthine approach with resection of cranial nerves VII and VIII, followed by facial-hypoglossal nerve anastomosis. Intraoperative frozen section suggested malignant spindle cell neoplasm, but final histopathological and molecular testing confirmed the lesion to be a GBM. The authors report the first case in which absence of any brainstem interface effectively excluded a primary parenchymal tumor, in particular GBM, from the differential diagnosis. Given the dramatic differences in treatment and prognoses between malignant glioma and MPNST, this case emphasizes the importance of surgical intervention on an aggressively growing lesion, which provides both the best probability of local control and the critical tissue diagnosis.