Stapedial Electromyograms Recorded by Electrocochleography

Abstract

The stapedial reflex (SR) can be obtained by the impedance method only when the middle ear is intact. In order to examine the function of the stapedius muscle in diseased ears, the recording of the stapedial electromyogram by an electrocochleographic (ECoG) method was considered. The SR was recorded simultaneously by the impedance method in ten normal subjects for comparison. The outputs of ECoC were averaged by a signal processor up to 200 times under a longer sweep time, and a large biphasic wave with a latency of about 11 ms was obtained on the ECoC records. The amplitude increase of the biphasic wave caused by raising the intensity of the acoustic stimulation paralleled that of the SR. This means that the biphasic wave obtained by ECoC with a latency of about 11 ms originated from the stapedius muscle.