Vestibular evoked myogenic potentials in chronic otitis media before and after surgery

Conclusion. The pathology of chronic otitis media (COM) could delay and reduce the energy transfer of sound to the inner ear. The significant improvement of postoperative vestibular evoked myogenic potential (VEMP) response rate and p13 latencies in the group of patients with no or negative postoperative ABG gain provided evidence that the sound energy inducing a VEMP might be different from the energy producing the auditory perception. Objective. To evaluate the VEMP in patients with COM before and after surgery. Subjects and methods. Twenty-four subjects with unilateral COM were enrolled. A pure tone audiogram and VEMP using 500 Hz unilateral short tone-burst stimulations were recorded before and 3 months after surgery. The postoperative VEMP responses were compared with the responses before surgery and the healthy controls. Results. After surgery, the 500 Hz airbone gap (ABG) decreased significantly and the VEMP response rate increased significantly from 41.7% to 66.7% (p<0.05, bi-test). However, both the preoperative and postoperative p13 latencies were significantly longer than those of the healthy controls (p<0.05, Wilcoxon rank-sum test). In the 18 patients whose 500 Hz ABG did not improve with surgery, the p13 latencies were significantly shorter postoperatively (p<0.05, sign test), and the response rate also improved significantly from 44.4% (8/18) to 77.8% (14/18) (p<0.05, bi-test).