Myogenic influences on the electrical auditory brainstem response (EABR) in humans.

Two cases demonstrating the effects of myogenic artifact on the electrical auditory brainstem response (EABR) when using a promontory stimulation site are presented. Intensity-response functions were obtained in the unparalyzed condition, then repeated after infusion of a neuromuscular paralyzing agent. In both cases, the myogenic response was observed at lower stimulus intensities than the EABR components. As intensity increased, the myogenic responses grew at extremely rapid rates and made any subsequent identification of auditory responses virtually impossible. To alleviate the adverse influence of myogenic components, general anesthesia and a paralyzing agent must be incorporated into the test protocol when acquiring the EABR using a promontory site of stimulation.