Studies with Electrocochleography and Auditory Brainstem Response in Ramsay Hunt Syndrome

Eighteen cases of Ramsay Hunt syndrome were examined with electrocochleography and auditory brainstem response. Hearing was normal in 4 cases, while the other 14 exhibited sensorineural hearing loss ranging from mild to moderate in severity. Although the I-V interwave latency in all cases was within or slightly outside of the normal limits, the N1 latency was significantly prolonged in 8 cases proportionately to the degree of hearing loss at 4 and 8 kHz. The histopathological findings reported so far have indicated that the main lesion in this syndrome is in the internal auditory canal (2, 3, 4, 5). The results obtained in the present study, however, clearly show that the main site responsible for the hearing loss is not in the retrocochlear region, but in the cochlea. The possible mechanism of the cochlear involvement in this syndrome was discussed.