Intratympanic Injection of Edaravone for Idiopathic Sudden Sensorineural Hearing Loss with Profound Hearing Loss

BACKGROUND: In Japan, edaravone, a free radical scavenger, is used clinically to reduce neuronal damage after acute cerebral infarction. In this study, a clinical trial has been designed utilizing intratympanic edaravone injection (ITE), which was hypothesized to exhibit high transitivity into the inner ear, with the aim of identifying an improved treatment modality for patients with idiopathic sudden sensorineural hearing loss (ISSHL) presenting with profound hearing loss. METHODS: Between April 2012 and December 2015, 17 patients with ISSHL, with mean hearing levels equal to or greater than 90 dB HL at the time of the initial visit, were treated with ITE. Fourteen patients with ISSHL under the same conditions were extracted, who received intratympanic steroid injection (ITS) in the department between January 2015 and December 2019 as a historical control. The hearing thresholds were compared between the ITE and ITS groups. RESULTS: The improvement between the initial and final hearing levels was significantly greater in the ITE group than in the ITS group at 250-1000 Hz. The average hearing improvement was 49.1 (+/- 21.0) dB in ITE group and 35.2 (+/- 11.8) dB in ITS group, and the degree of improvement was significantly greater in ITE group. No detectable adverse events associated with ITE were observed in patients' subjective symptoms. CONCLUSION: The final hearing thresholds of patients treated with ITE were significantly better than those of patients treated with ITS. It has been concluded that ITE treatment may be useful in future clinical studies.