Does intratympanic gentamicin treatment for Meniere's disease cause complete vestibular ablation?

Objective: To determine changes in vestibular function following intratympa nic gentamicin (ITG) treatment for Meniere's disease and to correlate chang es with the need for further treatment. Study Design: Prospective case series. Patients: One hundred and three patients with disabling unilateral Meniere' s disease who had failed a minimum of 6 months medical treatment. Main Outcome Measures: Vestibular function was measured by electronystagmog raphy (ENG) caloric resting before and serially following treatment. Calori c responses were classified as normal (excitability difference [ED] < 25%), bithermal response (ED greater than or equal to 25%), positive response to ice water only, and absent ice water response. Results: Twenty-one percent of patients had a bithermal caloric response, 6 2% had an absent ice water response, and 17% had an ice water response only 1 month following treatment. Mean follow-up was 27.3 months (range = 1-106 months). Eighty-four patients had one treatment course only. Fourteen pati ents required a further course of treatment due to recurrence of vertigo; 3 8% of these had recovery of caloric function. Significantly more patients w ith normal caloric function prior to initial treatment required further tre atment compared to those with initial reduced caloric function (p < .05). P atients rendered absent ice water responsive were significantly less likely to require further treatment than those with a persistent caloric response (p < .0001). Conclusion: An absent ice water response is highly predictive of adequate v ertigo control. Regimens of ITG that aim to completely ablate vestibular fu nction are recommended.