Objective Controlled and uncontrolled studies with primary intratympanic (IT) or combined intratympanic and systemic application of glucocorticosteroids for idiopathic sudden hearing loss (ISSHL) were analyzed by means of a meta-analysis in an attempt to establish optimal local drug delivery protocols. Study Design A total of 25 studies with 28 treatment groups between January 2000 and June 2014 were selected that adequately described drug delivery protocols. Cochlear drug levels were calculated by a validated computer model of drug dispersion in the inner ear fluids based on the concentration and volume of glucocorticoids applied, the time the drug remained in the middle ear, and on the specific timing of injections. Various factors were compared with hearing outcome, including baseline data, individual parameters of the application protocols, calculated peak concentration (Cmax), and total dose (Area under the curve, AUC). Results There was no dependence of hearing outcome on individual parameters of the application protocol, Cmax or AUC. Final hearing threshold was notably independent of delay of treatment. Conclusion During primary IT or combined steroid therapy of ISSHL, the tendency towards early treatment having a positive effect on hearing improvement is thought to be a “sham effect”, likely related to spontaneous recovery. Change in pure tone average (PTA) may not be an adequate outcome parameter to assess effectiveness of the intervention, as it depends on the degree of initial hearing loss. Final PTA provides a better alternative.

Based on the available data from uncontrolled and controlled randomized and non-randomized studies no clear recommendation can be made so far for a specific application protocol for either primary or secondary (salvage) intratympanic steroid treatment in patients with ISSHL. For meta-analyses, change in pure tone average (PTA) may not be an adequate outcome parameter to assess effectiveness of the intervention especially with inhomogeneity of patient populations. Final PTA might provide a better outcome parameter.