Free radical scavenger protects against inner hair cell loss after cochlear ischemia.

We investigated the protective effects of edaravone, a free radical scavenger, against ischemic damage of inner hair cells (IHCs) in gerbils. Cochlear ischemia was induced in the animals by occluding the vertebral arteries bilaterally for 15 min. Edaravone (1 mg/kg, i.v.) or saline was administered 1 h after ischemia. Hearing was assessed by auditory brain response (ABR). In animals treated with saline, the ABR threshold shift was 24.1 dB and there was a 26.5% decrease in the number of IHCs. By contrast, in animals treated with edaravone, the threshold shift was 7.5 dB and only 8.8% of IHCs was lost. These results suggest that edaravone protects against damage to the inner ear following transient ischemia.