Acoustic tumor detection with brain stem electric response audiometry.

Tumors that press on the audiotry nerve can cause a latency increase that is detectable from the scalp by electric response audiometry (BERA). The response delay is best seen by comparing the Jewett wave V, or P5, latencies for the two ears. This interaural latency difference is normally less than 0.2 msec, but was 0.4 msec or greater for 35 acoustic tumor cases and for seven of ten other temporal bone tumors. Acoustic tumor size can be estimated from the amount of latency delay.