VEMPs and dynamic posturography after intratympanic gentamycin in Menière's disease

In this study, we investigated whether vestibular evoked myogenic potentials (VEMPs) and dynamic posturography (DP) are useful in the evaluation of the vestibular function in patients affected by active monoaural Menière's disease (MD) treated with intratympanic gentamycin. Twelve subjects affected by monoaural MD were treated with weekly intratympanic injections of 0.5 ml of gentamycin at a concentration of 20 mg/ml. VEMPs were used to test saccular function, while postural control was analyzed by DP. The results obtained with these two techniques were compared with those obtained by using bithermal caloric test. The mean follow-up was 15.3 months (6--28 months). Therapy resulted in complete absence of the caloric response in six subjects (50) and in caloric test-induced asymmetry in the remaining individuals, ranging from 83 to 27. At follow-up, eleven patients (91.6%) were free of vertigo, while one patient had two vertigo spells 9 months after treatment. Before treatment, VEMPs were present in the affected ear of eleven patients. After treatment VEMPs were absent in all the patients. At the end of follow-up, reappearance of VEMPs was observed in two patients, with no changes in latency values and amplitude ratio. DP demonstrated a reduction of the Composite Score (CS) one week after therapy, with a prevalent reduction of the vestibular component. After 6 months, there was an improvement of the CS and, in particular, of the vestibular component. The present study demonstrates that bithermal caloric test and VEMPs allow for the functional evaluation of both the horizontal semicircular canal and the sacculus, suggesting that these techniques might be used together to monitor the efficacy of intratympanic gentamycin therapy. In addition, our data indicate that DP might provide important information on compensation phenomena and show that intratympanic gentamycin can improve postural control in MD patients.