Faculty Bibliography

BACKGROUND:Hearing preservation is a goal for many patients with vestibular schwannoma. We examined pretreatment magnetic resonance imaging (MRI) and posttreatment hearing outcome after stereotactic radiosurgery. METHODS:From 2004 to 2014, a cohort of 125 consecutive patients with vestibular schwannoma (VS) treated via stereotactic radiosurgery (SRS) were retrospectively reviewed. MRIs containing three-dimensional constructive interference in steady state or equivalent within 1 year before treatment were classified by two radiologists for pretreatment characteristics. "Good" hearing was defined as American Academy of Otolaryngology-Head and Neck Surgery class A. Poor hearing outcome was defined as loss of good pretreatment hearing after stereotactic radiosurgery. RESULTS:Sixty-one patients met criteria for inclusion. Most had tumors in the distal internal auditory canal (55%), separated from the brainstem (63%), oval shape (64%) without cysts (86%), and median volume of 0.85 ± 0.55 cm. Pretreatment audiograms were performed a median of 108 ± 173 days before stereotactic radiosurgery; 38% had good pretreatment hearing. Smaller tumor volume (p < 0.005) was the only variable associated with good pretreatment hearing. 49 (80%) patients had posttreatment audiometry, with median follow-up of 197 ± 247 days. Asymmetrically decreased pretreatment cochlear CISS signal on the side of the VS was the only variable associated with poor hearing outcome (p = 0.001). Inter-rater agreement on cochlear three-dimensional constructive interference in steady state preservation was 91%. CONCLUSIONS:Decreased cochlear CISS signal may indicate a tumor's association with the cochlear neurovascular bundle, influencing endolymph protein concentration and creating an inability to preserve hearing. This important MRI characteristic can influence planning, counseling, and patient selection for vestibular schwannoma treatment.

OBJECTIVE The incidence of brain metastases is increasing with improved systemic therapies, many of which have a limited impact on intracranial disease. Stereotactic radiosurgery (SRS) is a first-line management option for brain metastases. The purpose of this study was to determine if there is a threshold tumor size below which local control (LC) rates approach 100%, and to relate these findings to the use of routine surveillance brain imaging. METHODS From a prospective registry, 200 patients with 1237 brain metastases were identified who underwent SRS between December 2012 and May 2015. The median imaging follow-up duration was 7.9 months, and the median margin dose was 18 Gy. The maximal diameter and volume of tumors were measured. Histological analysis included 96 patients with non-small cell lung cancers (NSCLCs), 40 with melanoma, 35 with breast cancer, and 29 with other histologies. RESULTS Almost 50% of brain metastases were NSCLCs and commonly measured less than 6 mm in maximal diameter or 70 mm3 in volume. Thirty-three of 1237 tumors had local progression at a median of 8.8 months. The 1- and 2-year actuarial LC rates were 97% and 93%, respectively. LC of 100% was achieved for all intracranial metastases less than 100 mm3 in volume or 6 mm in diameter. Patients whose tumors at first SRS were less than 10 mm maximal diameter or a volume of 250 mm3 had improved overall survival. CONCLUSIONS SRS can achieve LC rates approaching 100% for subcentimeter metastases. The earlier initial detection and prompt treatment of small intracranial metastases may prevent the development of neurological symptoms and the need for resection, and improve overall survival. To identify tumors when they are small, routine surveillance brain imaging should be considered as part of the standard of care for lung, breast, and melanoma metastases. CLASSIFICATION OF EVIDENCE Type of question: prognostic; study design: retrospective cohort; evidence: Class II.

Purpose: Prior studies have shown correlation between relative cerebral blood volume (rCBV) and patient survival and tumor genomics. The purpose of this study was to determine whether rCBV values correlate with isocitrate dehydrogenase (IDH) mutation status, genome-wide CNV (copy number variation) and patient overall survival in diffuse gliomas. Materials & Methods: 107 treatment naive gliomas (62 patients from TCGA/TCIA dataset and 45 patients from our institute) (44 glioblastoma and 63 lower grade gliomas) with DSC T2* perfusion data were included. IDH mutation and survival data were assayed by the TCGA, and pre-surgical imaging collected by The Cancer Imaging Archive. CNVabundance plots obtained with Illumina 850k EPIC DNA methylation arrays were reviewed in 19 patients. The association of rCBV with tumor genomics, CNV and overall survival were analyzed. Results: IDH-wildtype gliomas (44.8%) demonstrated higher rCBV values (rCBV = 6.87 +/- 3.09) than IDH-mutated gliomas (55.2%, rCBV =2.21 +/- 1.71 for 1p/19q codeleted gliomas and 2.09 +/- 2.00 for non-codeleted gliomas, ANOVA, p<0.0001). rCBV is a significant predictor of overall survival (HR 1.23, p<0.0001). Gliomas with rCBV < 3.80 showed better survival (n = 54, median survival time unobserved) than gliomas with rCBV > 3.8 (n = 53, median 18 months; log-rank p<0.0001). IDHwt gliomas with high rCBV had the worst survival (10.6% surviving at 3 years, 95% CI (4%, 30%)). CNV-S IDHmut 1p19q noncodeleted gliomas demonstrated significantly lower mean rCBV (1.4 +/- 0.4) than CNV-U gliomas (4.0 +/- 1.1, p = 0.009). Conclusion: IDHwt gliomas show higher rCBV than IDHmut gliomas irrespective of the glioma grade. Higher rCBV measurements are associated with poorer survival in the entire cohort and also within IDHmut and IDHwt gliomas. IDHmut 1p19q noncodeleted gliomas with higher CNV abundance (CNV-U) also show higher CBV when compared with those with lesser degree of CNVabundance (CNV-S)

Background/UNASSIGNED:While effective for the repair of large skull base defects, the Hadad-Bassagasteguy nasoseptal flap increases operative time and can result in a several-week period of postoperative crusting during re-mucosalization of the denuded nasal septum. Endoscopic transsphenoidal surgery for pituitary adenoma resection is generally not associated with large dural defects and high-flow cerebrospinal fluid (CSF) leaks requiring extensive reconstruction. Here, we present the posterior nasoseptal flap as a novel technique for closure of skull defects following endoscopic resection of pituitary adenomas. This flap is raised in all surgeries during the transnasal exposure using septal mucoperiosteum that would otherwise be discarded during the posterior septectomy performed in binostril approaches. Methods/UNASSIGNED:We present a retrospective, consecutive case series of 43 patients undergoing endoscopic transsphenoidal resection of a pituitary adenoma followed by posterior nasoseptal flap placement and closure. Main outcome measures were extent of resection and postoperative CSF leak. Results/UNASSIGNED:The mean extent of resection was 97.16 ± 1.03%. Radiographic measurement showed flap length to be adequate. While a defect in the diaphragma sellae and CSF leak were identified in 21 patients during surgery, postoperative CSF leak occurred in only one patient. Conclusions/UNASSIGNED:The posterior nasoseptal flap provides adequate coverage of the surgical defect and is nearly always successful in preventing postoperative CSF leak following endoscopic transsphenoidal resection of pituitary adenomas. The flap is raised from mucoperiosteum lining the posterior nasal septum, which is otherwise resected during posterior septectomy. Because the anterior septal cartilage is not denuded, raising such flaps avoids the postoperative morbidity associated with the larger Hadad-Bassagasteguy nasoseptal flap.