Acoustic stapedial reflex latency versus BERA wave V latency in the detection of eighth nerve lesions

Abstract

The parameter of latency of the acoustic stapedial reflex was used to test the hypothesis that a retrocochlear lesion involving the afferent portion of the reflex arc will result in a slowed neural conduction time. Measurements of middle-ear muscle activity were made by use of an electro-acoustic impedance bridge modified to permit presentation of tonal stimuli 300 ms in duration with 10-ms rise/fall time for test frequencies of 1000 and 2000 Hz. Both contralateral and ipsilateral values were obtained for absolute reflex latency and interaural latency differences on four clinical populations which included cochlear lesions due to Meniere's disease and surgically confirmed acoustic tumor. Results reveal a dramatic prolongation of latency in the presence of retrocochlear lesions. Comparisons drawn between the acoustic reflex latency test and BERA wave V latency, obtained with tone pip stimuli, indicate that stapedial reflex latency is a more efficient method of tumor detection. [Work supported by American Hearing Research Foundation, Chicago, IL.]