Measurements of Trunk Sway for Stance and Gait Tasks 2 Years after Vestibular Neurectomy

The aim of this study was to investigate changes in balance control for stance and gait tasks in patients 2 years before and after vestibular neurectomy (VN) performed to alleviate intractable Meniere's disease. Amplitudes of trunk sway in roll and pitch directions were measured for stance and gait tasks in 19 patients using gyroscopes mounted at the lower-back. Measurements before VN and 2 years later were compared to those of healthy age-matched controls (HC). We also examined if changes in trunk sway amplitudes were correlated with patients' subjective assessment of disability using the AAO-HNS scale. For patients with low AAO-HNS scores 0-2 (n = 14), trunk roll and pitch sway velocities, standing eyes closed on foam, increased 2 years post VN compared to HC values (p < 0.01). Trunk sway amplitudes remained at levels of HC for simple gait tasks, but task durations were longer and therefore gait slower. For complex gait tasks (stairs), balance control remained impaired at 2 years. In patients with AAO-HNS high scores level 6 (n = 5), balance control remained abnormal, compared to HC, 2 years postoperatively for all stance, several simple and all complex gait tasks. Trunk sway in the pitch and roll directions for stance tasks was correlated with clinical (AAO-HNS) scores (p ≤ 0.05). These results indicate that VN leads to chronic balance problems for stance and complex gait tasks. The problems are greater for patients with high compared to low AAO-HNS scores, thereby explaining the different symptoms reported by these patients. The lack of balance recovery in VN patients to levels of HCs after 2 years contrasts with the 3 months average recovery period for acute vestibular neuritis patients and is indicative of the effects of neurectomy on central compensation processes.