Prediction of auditory brainstem wave V latency as a diagnostic tool of sensorineural hearing loss

The lesion location (cochlear vs. retrocochlear) of sensorineural hearing loss may be differentiated with a diagnostic index (delta V), which is calculated from the wave V latency of the monaurally evoked auditory brainstem response (ABR), and from the pure-tone hearing threshold at 2 and 4 kHz. The delta V values obtained from 80 recruiting ears have proven to correlate linearly to the amount of the hearing loss, hence allowing to define appropriate confidence boundaries for cochlear hearing losses. In contrast, the delta V values obtained from 32 ears of patients with retrocochlear lesions--cerebellopontine angle (CPA) tumors--were all found to exceed the 95% upper confidence limits projected for cochlear lesions, thus giving a 100% rate of true results in the detection of retrocochlear pathology. These results, providing an ABR parametric model for the cochlear hearing loss, suggest a diagnostic strategy for the early detection of CPA tumors based on the exclusion of a cochlear hearing loss.