Contralesional High-Acceleration Vestibulo-Ocular Reflex Function in Vestibular Schwannoma

Impairment of ipsilesional vestibulo-ocular reflex (VOR) function is well described in vestibular schwannoma (VS) and a correlation between gain of the VOR and tumor size has been suggested. Bilateral VOR impairment may also occur in VS patients, but its mechanisms are poorly understood. We sought to explore the effect of unilateral VS on ipsilesional and contralesional high-acceleration VOR function using video head impulse testing, and evaluate potential factors responsible for contralesional VOR impairment.

Chart review in tertiary referral center of patients with unilateral VS, who completed neurotological examination and vestibular function testing.

One hundred one patients (mean age 57.4 yrs) were included. Maximal tumor diameter ranged from 0.3 to 5.0 cm. Forty one patients had evidence of brainstem compression from VS on magnetic resonance imaging (MRI). Ipsilesional and contralesional VOR impairment was present in 81 (80%) and 44 (43%) patients, respectively. Bilateral VOR impairment was seen in 42 (42%) patients. Bilateral VOR impairment correlated with tumor size. Presence of brainstem compression was associated with reduced ipsilesional VOR gain, but not contralesional VOR gain.