Diagnostics and Therapy of Idiopathic Sudden Sensorineural Hearing Loss

Abstract

This article reviews recent aspects of diagnostics, differential diagnostics and evidence in systemic and local therapy of idiopathic, sudden, sensorineural hearing loss (ISSHL). Since a number of disorders can be accompanied by sudden hearing loss a meaningful and targeted diagnostic strategy is of utmost importance. An important differential diagnosis of sudden hearing loss are intralabyrinthine schwannomas (ILS). The incidence of ILS is probably significantly underestimated. This may be due to the lack of awareness or lack of explicit search for an intralabyrinthine tumor on MRI or an inappropriate MRI technique ('head-MRI' instead of 'temporal bone-MRI' with too high slice thickness) for the evaluation of sudden hearing loss. Therefore, the request to the radiologist should specifically include the question for (or exclusion of) an ILS. With special MRI techniques, it is today possible to visualize an endolymphatic hydrops. The evidence in the therapy of ISSHL is - with respect to quality not quantity of studies - unsatisfying. The value of systemically (low dose) or intratympanically applied corticosteroids in the primary treatment of ISSHL is still unclear. In order to investigate the efficacy and safety of high dose corticosteroids in primary treatment for ISSHL a national, multicenter, three-armed, randomized, triple-blind controlled clinical trial is currently performed in Germany (http://hodokort-studie.hno.org/). After insufficient recovery of threshold with systemic therapy of ISSHL, intratympanic corticosteroid therapy appears to be associated with a significantly higher chance of improvement of hearing threshold than no therapy or placebo. Both, hearing gain and final hearing thresholds, however, appear to be independent of the start of secondary therapy. Based on the currently available data from clinical studies, no recommendation can be made with respect to type of corticosteroid and specifics of the intratympanic application protocol.