Article Abstract

Inner ear patency after retrosigmoid vestibular schwannoma resection

Authors: Alasdair Grenness, Fiona C. E. Hill, Shannon Withers, Claire Iseli, Robert Briggs

Abstract

Background: Unilateral hearing loss post retrosigmoid (RS) vestibular schwannoma (VS) resection remains a significant issue. Cochlear implantation (CI) may restore this loss if the cochlear nerve is preserved. Little is known about inner ear patency and fibrosis post RS VS resection which may preclude implantation. This study aimed to investigate the patterns of fibrosis post RS VS resection.
Methods: Inner ear patency was investigated using post-operative T2 magnetic resonance imaging (MRI) scans in patients post RS VS resection. Patterns of vestibular and cochlear labyrinth fluid signal change were categorised and correlated with hearing outcomes.
Results: Thirty-one patients over a 4-year period were included in the study. Twenty-one patients had a normal cochlear fluid signal on their first post-operative scan (68%) and all subsequent scans. Ten patients had evidence of cochlear fluid signal loss on their first scan (32%) and 6 of these progressed on subsequent imaging (60%). Identifiable hearing outcomes were available for 29 patients. Nine patients preserved hearing at any frequency (31%) and 6 of these had serviceable hearing (21%). All patients with loss of labyrinth fluid signal had no detectable hearing.
Conclusions: The majority of patients post RS VS resection maintained a patent cochlea. However, a large number developed evidence of fibrosis with progression on subsequent imaging. Individuals who meet the criteria for CI and have early cochlear fluid signal changes on post-operative MRI should ideally undergo early implantation to maximize the chances of successful implantation.