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MO_7_2637 - Stereotactic Radiosurgery (SRS) for Vestibular Schwannoma: Longitudinal Audiologic Assessment in Single and Fractionated Treatments.

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Stereotactic Radiosurgery (SRS) for Vestibular Schwannoma: Longitudinal Audiologic Assessment in Single and Fractionated Treatments.
M. H. Khattab1, D. M. Wharton2, E. Kim3, L. B. Chambless4, K. Weaver4, G. Luo3, A. Yock3, M. Morales2, A. J. Cmelak2, and A. Attia2; 1Vanderbilt University Medical center, Nashville, TN, 2Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN, 3Vanderbilt University Medical Center, Nashville, TN, 4Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN

Purpose/Objective(s): Fractionated stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) has been hypothesized to allow for tumor control with higher rates of hearing preservation in select patients with useful hearing. However, there is a paucity of literature with formal audiologic measures of hearing preservation to support the standard use of fractionated SRS in VS. We hypothesized that fractionation would diminish the amount of hearing damage.

Materials/Methods: We performed an IRB approved retrospective review of patients treated with 1, 3, or 5 fx SRS for VS at our institution from 1998-2016. Pre- and post- SRS audiograms with speech awareness threshold (dB) in treated and contralateral ears were obtained. Contralateral ear measurements were used for hearing normalization to account for any age-related hearing loss.

Results: A total of 56 patients met selection criteria. Post-SRS audiograms were recorded at a median of 32 months after SRS treatment (range 3 to 139). Most patients were treated with 5 fractions (32, 57%), then 3 fractions (12, 21%) and 1 fraction (12, 21%). The most common dose and fractionation regimens were 1250 cGy x 1 (7, 12.5%), 700 cGy x 3 (12, 21.4%), 500 cGy x 5 (12, 21.4%), and 450 cGy x 5 (14, 25%). The median baseline hearing threshold with 1 fx was 45 (range 10-105), compared to 3 fx median 37.5 (range 15-75) and 5 fx median 45 (range 10-100). The median difference in treated hearing was 32.5 (range 20 to 45) for 1 fx (only 2 patients with sufficient data to calculate this), 25 (range -5 to 35) for 3 fx (6 patients), and 10 (range -50 to 55) for 5 fx (19 patients). The median post-treatment hearing threshold was 52.5 (range 45 to 60) for 1 fx, 47.5 (range 15 to 80) for 3 fx, and 60 (range 20 to 85) for 5 fx. Collectively, all patients had a significant decline in hearing in the side treated with SRS, compared to the contralateral side (mean pre/post difference of 10; paired t-test p=0.03). However, the subset of patients treated with 5 fractions did not have a statistically significant decline in hearing in the treated compared to the contralateral side (p=0.39). Patients treated with 3 fractions had a borderline significant decrease in hearing in the treated vs contralateral side (p=0.06).

Conclusion: This retrospective analysis using audiologic evaluation supports the continued use of fractionated SRS to preserve hearing in patients with vestibular schwannomas and serviceable hearing.

Author Disclosure: M.H. Khattab: None. E. Kim: None. L.B. Chambless: Consultant; National Football League. K. Weaver: None. A. Yock: None. M. Morales: None. A. Attia: Employee; Vanderbilt University. Honoraria; Brainlab, qfix. Advisory Board; AstraZeneca. Travel Expenses; qfix. Director of Radiosurgery Program; Vanderbilt University. Nashville Volunteer Leadership Board Member; American Cancer Society.

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MO_7_2637 - Stereotactic Radiosurgery (SRS) for Vestibular Schwannoma: Longitudinal Audiologic Assessment in Single and Fractionated Treatments.



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