Efficacy and Safety of Intranasal Betahistine in the Treatment of Surgery-Induced Acute Vestibular Syndrome: A Double-Blind, Randomized, Placebo-Controlled Phase 2 Study

OBJECTIVE: To evaluate the safety and efficacy of AM-125 nasal spray (intranasal betahistine) in the treatment of surgery-induced acute vestibular syndrome (AVS). STUDY DESIGN: Prospective, double-blind, randomized, placebo-controlled exploratory phase 2 study with dose escalation (part A) followed by parallel dose testing (part B); open-label oral treatment for reference. SETTING: Twelve European study sites (tertiary referral centers). PATIENTS: One hundred and twenty-four patients 18 to 70 years old undergoing surgery for vestibular schwannoma resection, labyrinthectomy or vestibular neurectomy with confirmed bilateral vestibular function presurgery and acute peripheral vertigo postsurgery. INTERVENTIONS: AM-125 (1, 10, or 20 mg) or placebo or betahistine 16 mg p.o. t.i.d. for 4 weeks, starting 3 days postsurgery; standardized vestibular rehabilitation. MAIN OUTCOME MEASURES: Tandem Romberg test (TRT) for primary efficacy, standing on foam, tandem gait, subjective visual vertical and spontaneous nystagmus for secondary efficacy, Vestibular Rehabilitation Benefit Questionnaire (VRBQ) for exploratory efficacy; nasal symptoms and adverse events for safety. RESULTS: At treatment period end, mean TRT improvement was 10.9 seconds for the 20-mg group versus 7.4 seconds for the placebo group (mixed model repeated measures, 90% confidence interval = 0.2 to 6.7 s; p = 0.08). This was corroborated by nominally higher frequency of complete spontaneous nystagmus resolution (34.5% vs. 20.0% of patients) and improvement in the VRBQ; the other secondary endpoints showed no treatment effect. The study drug was well tolerated and safe. CONCLUSIONS: Intranasal betahistine may help accelerate vestibular compensation and alleviate signs and symptoms of vestibular dysfunction in surgery-induced AVS. Further evaluation in a confirmatory manner appears warranted.