The evoked response called the ABR (Auditory Brainstem Response) is affected by nerve compression by acoustic neuromas, but is not presently sensitive enough to detect small tumors. If the ABR could be used to detect tumors, it would reduce overall medical costs and also provide a means to judge rate of tumor progression. This project proposes to improve the sensitivity of the ABR to nerve compression by acoustic neuromas by two means: 1) using a new chirp-stimulus recently published, which provides stimulation of all VIIIth nerve fibers, including those subserving low-frequencies. 2) stimulating at very high stimulus repetition-rates. A new method has been developed by Abratech Corporation which permits recording the ABR at the high stimulus repetition-rates likely to be needed for detection of small tumors. The research proposed will test the sensitivity of the new method combined with the new chirp-stimulus, in patients who have small acoustic neuromas. This proposal is health-related because it is directed towards a known health-problem: the diagnosis and monitoring of acoustic neuromas.
