Korean J Otolaryngol-Head Neck Surg.  1998 Aug;41(8):984-987.

DPOAE in Acoustic Neuroma

Affiliations
  • 1Department of Otolaryngology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea. kslee2@amc.seoul.kr

Abstract

BACKGROUND: Evoked otoacoustic emissions (OAEs) are assumed to reflect healthy outer hair cell function. It is possible that these objective tests can provide some insight into the fundamental basis of the hearing loss exhibited by patients with acoustic neuromas. The primary aim of the present study was to examine the effects of acoustic neuromas on the amplitudes of evoked OAEs and to compare these findings with tumor-induced hearing levels.
MATERIALS AND METHODS
The amplitude and growth functions of distortion product otoacoustic emission (DPOAE) at 2f1-f2, elicited by two primary tones f1 and f2 with a constant frequency ratio f2/f1=1.22 and varing geometric mean values 0.5, 1, 2, 4, and 8 kHz, were measured for 13 patients with radiologically proven acoustic neuroma.
RESULTS
After comparing audiograms and DP-gram, we found four patients with neural hearing loss, seven patients with sensory (cochlear) hearing loss, and two patients with sensorineural (mixed) hearing loss. There was a strong correlation between the results of DPOAE and the tumor location or duration of symptom, whereas there was no correlation between tumor size and cochlear function.
CONCLUSION
DPOAEs can identify preoperatively the sensory (cochlear) components of hearing loss induced by an acoustic neuroma. These emissions are also useful with a battery of retrocochlear screen tests, but they could not be relied on solely to rule out central hearing disorders.

Keyword

DPOAE; Acoustic neuroma
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