The aim of this study was to determine if high-dose delivery of methylprednisolone to the round window can improve hearing after the failure of conventional treatment for sudden sensorineural hearing loss (SSHL). In 6 patients with SSHL an Intraear microcatheter was placed in the round window niche and methylprednisolone (62.5 mg/ml) was infused at a rate of 10 microl/h for 8-10 days. Audiometric assessments (including measurement of speech discrimination) were made at presentation, either every day or every other day during treatment and 5 days after the completion of perfusion. Perfusion of methylprednisolone was beneficial for all 6 patients, with a 16.25-25 dB improvement in hearing threshold. A dramatic improvement in speech discrimination was also noted in all patients. In conclusion, methylprednisolone perfused at the level of the round window membrane resulted in significant recovery of hearing function after the failure of standard treatment of SSHL.