Do predictive mechanisms improve the angular vestibulo-ocular reflex in vestibular neuritis?

Recovery from vestibular neuritis (VN) is often incomplete which leads to persistent vestibular imbalance during rapid head movements. Patients with unilateral vestibular lesions have a larger gain of the horizontal vestibulo-ocular reflex during active compared to passive head movements. To test whether this gain increase is related to predictive mechanisms we studied 15 patients with VN and 14 control subjects during predictable and unpredictable passive horizontal head impulses in the light and darkness. The vestibulo-ocular reflex showed a significantly shorter latency and higher gain in the light for predictable head impulses towards the ipsilesional side. However, this effect is small and might contribute but cannot exclusively account for the gain increase during active head movements.