Normal brain-stem auditory evoked potentials with abnormal latency-intensity studies in patients with acoustic neuromas

A. D. Legatt, T. A. Pedley, R. G. Emerson, B. M. Stein and M. Abramson
Department of Neurology, College of Physicians and Surgeons, Columbia University, New York.

Brain-stem auditory evoked potentials (BAEPs) are highly sensitive for detecting acoustic neuromas but false-negative results occur. We studied BAEPs preoperatively in 39 cases of acoustic neuroma. Absolute and interpeak latencies ipsilateral to the tumor, and interaural latency differences, were normal in four patients with small tumors. In three of these, however, results of latency-intensity studies were abnormal. In one patient, the latency-intensity result became normal postoperatively. If acoustic neuroma is suspected, and BAEPs are normal by usual criteria, latency-intensity functions should be examined to maximize chances of detecting a small tumor.