The influence of eyeball rotation on the results of auditory steady-state responses.

BACKGROUND Testing auditory steady-state responses consists in recording the electrophysiological response to an auditory stimulus. Due to this response, in addition to changes in electric potentials caused by neuron impulses in the auditory path, the sonomotor reflex can also be observed. The sonomotor reflex shows muscle responses to auditory events, and in the case of auditory evoked potentials it mainly consists of post-auricular muscle responses. When the eyes are rolled to the side during testing, the post-auricular muscle response to an auditory stimulus is stronger, which in turn can contribute to improving response detection. OBJECTIVES The aim of this study was to test the influence of eyeball rotation on the results of auditory steady-state responses. MATERIAL AND METHODS Auditory evoked potentials were tested in a group of ten people with normal hearing. Each person was examined three times: (i) with eyes closed, (ii) with eyes open looking straight ahead and (iii) with eyes open and rolled to the side. RESULTS The median electrophysiological response amplitude recorded when the eyes were rolled to the side was approximately 40% higher than the median response amplitude recorded in other positions (with eyes closed, and with eyes open looking straight ahead). At the same time, during tests with the eyes rolled to the side, a 170% increase in the noise median observed, compared to the tests conducted with the eyes closed. CONCLUSIONS Rolling the eyes to the side does not improve the detection of response, as the observed increase in noise amplitude is much higher than the increase in the amplitude of the electrophysiological response.