Comparison of the therapeutic efficacy of a fixed low-dose combination of cinnarizine and dimenhydrinate with betahistine in vestibular neuritis: a randomized, double-blind, non-inferiority study.

BACKGROUND: Vestibular neuritis (VN) is a strongly disabling disease of the peripheral vestibular system. Rapid and effective relief of symptoms is important to allow patients to promptly return to normal physical activity. OBJECTIVE: The aim of this prospective, randomized, double-blind study was to evaluate the efficacy of a fixed low-dose combination of cinnarizine and dimenhydrinate in unilateral VN in comparison with betahistine in terms of improvement of vertigo and concomitant symptoms, and performance in neurotological testing. METHODS: Sixty-two patients were randomized to receive either cinnarizine 20 mg/dimenhydrinate 40 mg as a fixed combination or betahistine 12 mg, each three times daily for 4 weeks. Vertigo and concomitant symptoms, activities of daily living (ADL), posturography and a battery of vestibulo-ocular tests, registered by electronystagmography including spontaneous nystagmus, bithermal caloric and rotatory test, among others, were assessed at baseline (t(0)), after 1 week (t(1w)) and after 4 weeks (t(4w)). The primary endpoint was the Mean Vertigo Score (MVS) at t(1w), a composite of 12 individual scores for unprovoked and provoked vertigo, each assessed using a 10 cm visual analogue scale (VAS). Non-inferiority of the fixed combination versus betahistine would be assumed if the two-sided 95% confidence intervals (CIs) for between-group differences in MVS lay entirely below the non-inferiority margin of 1.25 (12.5% of VAS range). RESULTS: The fixed combination led to significantly greater improvements in MVS than betahistine both at t(1w) (primary endpoint) and at t(4w) (95% CI for the difference in baseline-adjusted means -0.95, -0.64 at t(1w), -0.77, -0.44 at t(4w); p < 0.001). Vegetative symptoms and ADL also improved significantly more under the fixed combination than under betahistine at t(1w) (p < 0.001, each parameter) and t(4w) (p < 0.001 and p < 0.01, respectively), both showing a nearly complete remission at t(4w). In the two groups, pathological posturography and electronystagmography parameters normalized during the 4-week treatment. The fixed combination group showed an earlier recovery of spontaneous nystagmus than the betahistine group (t(1w), p < 0.001) and slightly higher improvements in asymmetry of rotation-induced nystagmus at t(1w) and t(4w) (p = 0.041, each time point). No significant differences were found between the treatments in abatement of spontaneous nystagmus at t(4w) and decrease of caloric lateralization or improvement of equilibrium (sensory organization test [SOT], conditions 5/6) at t(1w) and t(4w). No patient reported any adverse event. CONCLUSION: The results showed that the fixed low-dose combination of cinnarizine and dimenhydrinate is an effective and well tolerated option for symptomatic treatment in unilateral VN. The fixed combination led to significant improvements in vertigo and ADL within the first week, and to a nearly complete recovery after 4 weeks. Neurotological testing revealed no signs of a possible detrimental influence of the 4-week treatment with the fixed combination compared with betahistine in terms of recovery of caloric responsiveness and abatement of rotation-induced nystagmus.