Lgk In Vestibular Schwannomas: Impact On Anterior And Posterior Labyrinth

Ganau Mario1, Nazarena Mesiano1, Antonio Nicolato1, Michele Longhi1, Francesco Lupidi1, Antonio De Simone2, Roberto Foroni1, Jordana Sosa Carrero1, massimo a. gerosa3, Giuseppe Kenneth Ricciardi1

1Department of Neurosurgery, University Hospital, Verona, Italy 2Vr, Italy 3University of Verona- Italy

Keywords: vestibular schwannoma, hearing function, gamma knife, radiosurgery, skull base

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     LGK for vestibular schwannomas (VS) has proven to allow for satisfying hearing preservation.
     In the present study, we aim to specifically evaluate its impact on the vestibular system by electronystagmography (ENG) and computerized static stabilometry (CSS) for vestibulo-spinal reflex.
     Out of 512 patients harbouring symptomatic VS treated by LGK since 1993 at our Department, a smaller group of 52 unpreviously treated cases (31M/21F), mean age 58 years (range: 30-79) has been selected for this study. There were 28 patients with right and 24 with left VS, responsible for balance disorders, vertigo, tinnitus and hearing impairment (GR: I to III).
     Beside clinico-radiological examination which ruled out cranial nerves deficits and other neuropathies, hearing as well as vestibular functions were respectively assessed, pre- and post-radiosurgery, by audiometry (PTA), ABR, vocal-speech-discrimination-score (SDS), and ENG, CSS. On admission, balance disorders were present in 62%, tinnitus in 56%, and vertigo in 48% of our cohort, whereas progressive (50%), sudden (4%) and variable (6%) hypoacusia were detected. Mean and range treatment parameters were as follows: VS volume 2.01cc (0.06–10.4cc), prescription dose 12.8Gy (10–13.5Gy), maximal dose 25.30Gy (20–27Gy), and conformity index 1.27 (1– 2.27).
     Mean follow-up was 44,20 months (range: 25-60). Tumor growth control was achieved in 98% of cases on MRI scans.
     This is a retrospective study.
     According to specific testing procedures, LGK seems to guarantee high probability of hearing preservation.
     Also it seems to gaurantee for a long lasting improvement in vestibular functions, with a consequently better path in vestibulo-spinal reflex


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G. Mario (), N. Mesiano (), A. Nicolato (), M. Longhi (), F. Lupidi (), A. De Simone (), R. Foroni (), J. Carrero (), m. gerosa (), G. Ricciardi ()