Bone-conducted Vestibular-evoked Myogenic Potentials Before and After Stapes Surgery.

ABSTRACT

OBJECTIVE: To identify whether stapes surgery causes otolith dysfunction using bone-conducted vestibular-evoked myogenic potentials (VEMPs). STUDY DESIGN: Prospective study. SETTING: Hyogo College of Medicine Hospital. PATIENTS Twenty primary ears (19 otosclerosis, 1 congenital stapes fixation) in 17 patients (2 men, 15 women; mean age 51 yr, range 20-68 yr) who had normal cervical VEMP (cVEMP) and ocular VEMP (oVEMP) results with bone-conducted stimulation were included. INTERVENTION Stapes surgery. MAIN OUTCOME MEASURE: Both VEMP tests with bone-conducted stimulation were performed before and after stapes surgery. The normalized p13-n23 amplitude of cVEMPs and the nI-pI amplitude of oVEMPs were measured within 3 months after stapes surgery. Then, the asymmetry ratio (AR) was calculated to examine the effect of surgery on otolith function. RESULTS: Seven patients complained of temporary dizziness postoperatively, but their symptoms disappeared within approximately a week. Deterioration of VEMPs of the operated ear was not seen in any ears. Significantly greater amplitude compared with the opposite ear was found for cVEMP in one ear and oVEMP in two ears after the surgery. Their VEMP results recovered to the normal range at 6 months postoperatively. CONCLUSIONS: These findings suggest that stapes surgery causes no or undetectably small otolith dysfunction from the perspective of VEMP evaluation.