• Young-Hoon Kim, Dong Gyu Kim, Jung Ho Han, Hyun-Tai Chung, In Kyung Kim, Sang Woo Song, Jeong-Hoon Park, Jin Wook Kim, Yong Hwy Kim, Chul-Kee Park, Chae-Yong Kim, Sun Ha Paek, and Hee-Won Jung.
• Department of Neurosurgery, Seoul National University Bundang Hospital, Seongnam-si, Korea.
• Int. J. Radiat. Oncol. Biol. Phys. 2013 Jan 1;85(1):61-7.

PurposeWe evaluated the prognostic factors for hearing outcomes after stereotactic radiosurgery (SRS) for unilateral sporadic intracanalicular vestibular schwannomas (IC-VSs) as a clinical homogeneous group of VSs.Methods And MaterialsSixty consecutive patients with unilateral sporadic IC-VSs, defined as tumors in the internal acoustic canal, and serviceable hearing (Gardner-Roberson grade 1 or 2) were treated with SRS as an initial treatment. The mean tumor volume was 0.34±0.03 cm3 (range, 0.03-1.00 cm3), and the mean marginal dose was 12.2±0.1 Gy (range, 11.5-13.0 Gy). The median follow-up duration was 62 months (range, 36-141 months).ResultsThe actuarial rates of serviceable hearing preservation were 70%, 63%, and 55% at 1, 2, and 5 years after SRS, respectively. In multivariate analysis, transient volume expansion of ≥20% from initial tumor size was a statistically significant risk factor for loss of serviceable hearing and hearing deterioration (increase of pure tone average≥20 dB) (odds ratio=7.638; 95% confidence interval, 2.317-25.181; P=.001 and odds ratio=3.507; 95% confidence interval, 1.228-10.018; P=.019, respectively). The cochlear radiation dose did not reach statistical significance.ConclusionsTransient volume expansion after SRS for VSs seems to be correlated with hearing deterioration when defined properly in a clinically homogeneous group of patients.Copyright © 2013 Elsevier Inc. All rights reserved.

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