Study of Emission Cochleogram in Patients with Acoustic Neuromas

Abstract

The emission cochlegram was investigated in 11 cases of surgically proven unilateral acoustic neuroma. Stimulus sounds were tone-bursts with the duration of 3ms at 5 frequencies between 1kHz and 4kHz. The results obtained were as follows;
1) The emission cochleograms showed similar configurations in the unaffected ears, but showed various configurations in the tumor-bearing ears.
2) The averaged emission cochleogram of the unaffected ears showed the high-tone abrupt loss type of configuration, while that of the tumor-bearing ears showed the high-tone gradual loss type due to the elevation of pseudothreshold between 1kHz and 2kHz.
3) The comparison between pure tone audiogram and emission cochleogram could enable to speculate the pathophysiology of hearing loss in each case of acoustic neuromas.
4) The pathophysiology of hearing loss might differ on the different cochlear partitions in some tumor-bearing ears.