Recovery of the horizontal vestibulo-ocular reflex in motorized head impulse test is common after vestibular loss

Decreased horizontal vestibulo-ocular reflex (VOR) gain measured with the motorized head impulse rotator usually recovers at least partially within a few months after sudden unilateral vestibular loss. In addition to traditional evaluation of nystagmus, head impulse test responses provide valuable information on the severity and recovery of vestibular loss.

To quantify recovery of vestibular function with the motorized head impulse test in patients with acute unilateral peripheral vestibular loss, and to compare these results with other signs and symptoms.

We recorded prospectively the horizontal VOR with the motorized head impulse rotator in 30 patients with sudden unilateral vestibular deficit on average 3 days after the onset (early). Twenty patients were measured sequentially on average 3 months later (late). We calculated VOR gain and asymmetry (mean ± standard deviation).

The early ipsilesional gain of 0.49 ± 0.21 improved highly significantly to the late gain of 0.79 ± 0.23 (p = 0.0000). The respective asymmetry improved highly significantly from 32 ± 18% to 12 ± 14% (p = 0.0002). Gain or asymmetry recovered at least partially in 80% of the patients. The late high symptom score correlated with low gain (p = 0.043) and high asymmetry (p = 0.018).