• Neurosurgery · Jan 2024

    Impact of the Mean Cochlear Biologically Effective Dose on Hearing Preservation After Stereotactic Radiosurgery for Vestibular Schwannoma: A Retrospective Longitudinal Analysis.

    • Constantin Tuleasca, Iuliana Toma-Dasu, Sebastien Duroux, Mercy George, Raphael Maire, Roy Thomas Daniel, David Patin, Luis Schiappacasse, Alexandru Dasu, Mohamed Faouzi, and Marc Levivier.
    • Lausanne University Hospital (CHUV), Neurosurgery Service and Gamma Knife Center, Lausanne , Switzerland.
    • Neurosurgery. 2024 Jan 1; 94 (1): 174182174-182.

    Background And ObjectivesStereotactic radiosurgery (SRS) is a useful alternative for small- to medium-sized vestibular schwannoma. To evaluate whether biologically effective dose (BED Gy2.47 ), calculated for mean (BED Gy2.47 mean) and maximal (BED Gy2.47 max) cochlear dose, is relevant for hearing preservation.MethodsThis is a retrospective longitudinal single-center study. Were analyzed 213 patients with useful baseline hearing. Risk of hearing decline was assessed for Gardner-Robertson classes and pure tone average (PTA) loss. The mean follow-up period was 39 months (median 36, 6-84).ResultsHearing decline (Gardner-Robertson class) 3 years after SRS was associated with higher cochlear BED Gy2.47 mean (odds ratio [OR] 1.39, P = .009). Moreover, BED Gy2.47 mean was more relevant as compared with BED Gy2.47 max (OR 1.13, P = .04). Risk of PTA loss (continuous outcome, follow-up minus baseline) was significantly corelated with BED Gy2.47 mean at 24 (beta coefficient 1.55, P = .002) and 36 (beta coefficient 2.01, P = .004) months after SRS. Risk of PTA loss (>20 dB vs ≤) was associated with higher BED Gy2.47 mean at 6 (OR 1.36, P = .002), 12 (OR 1.36, P = .007), and 36 (OR 1.37, P = .02) months. Risk of hearing decline at 36 months for the BED Gy2.47 mean of 7-8, 10, and 12 Gy 2.47 was 28%, 57%, and 85%, respectively.ConclusionCochlear BED Gy2.47 mean is relevant for hearing decline after SRS and more relevant as compared with BED Gy2.47 max. Three years after SRS, this was sustained for all hearing decline evaluation modalities. Our data suggest the BED Gy2.47 mean cut-off of ≤8 Gy 2.47 for better hearing preservation rates .Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Congress of Neurological Surgeons.

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