The application of vestibular evoked myogenic potentials (VEMP) in otoneurosurgery

Abstract

Objectives: It is the aim of the present paper to use VEMP recordings in the perioperative assessment of patients who have to undergo various otoneurosurgical or otosurgical procedures Methods: VEMP recordings were done routinely by bone-conduction stimulation at the mastoid and EMG recording at the sternocleidomastoid muscle (SCM) of each side before and after the surgery. The intraoperative stimulation was done at the vestibular nerve by a monopolar electrode (VIKING IV) with different impulses. The patients (56) underwent cochlear implantations(CI) (28), acoustic tumor removals (AN) (via different approaches)(19), microvascular decompressions (MVD)9). They had previously various degree of vertigo (DHI). The follow-up was 2 years. Results: VEMP recordings could only successfully be performed intraoperatively when they could be preoperatively elicited. A preservation of VEMP was related to a decrease in vertigo after the operation (AN/MVD). A postoperative loss of VEMP was accompanied by long-term instability, enhanced in the dark and on fast movements and in elderly (AN/CI). Conclusions: VEMP can be reliably recorded in this way. They can also be recorded in deaf patients and originate from the otolith organs (saccule). They provide additional helpful information for the surgeon in otoneurosurgery about the function of the inferior branch of the vestibular nerve (AN/MVD) and about the otolithic part of the labyrinth (CI). Loss of VEMP require long-standing vestibular rehabilitation, particularly in the elderly.