Vestibulo-ocular reflex abnormality in Parkinson's disease detected by video head impulse test.

Abstract

Parkinson's disease (PD) is a common neurodegenerative disease characterized by dopaminergic neuronal loss. The underlying cause of PD is unknown. To assess the clinical relevance of vestibular-ocular reflex (VOR) gain in patients with PD, especially those in the early stages. Sixty-three PD patients and 56 control healthy individuals were enrolled in this study between Mar 2015 and Aug 2015. VOR gains were determined by video head impulse test (vHIT) device. Statistical analysis was performed to assess the difference in VOR gains between PD patients and normal people. The relationship of VOR gain with age, duration and severity of disease was also assessed. In the control group, average VOR gain was 0.98±0.09 on the left side and 0.99±0.16 on the right side. No statistically significant difference was observed between the two sides in the control group (P>0.05). In the PD group, average VOR gain was 1.20±0.22 on the left side and 1.23±0.23 on the right side. No statistically significant difference was observed between the two sides in the PD group (P>0.05). There was a significant difference in VOR gain between the PD (both in early and mid-late stages) and the control group (P<0.05). A weak correlation was observed between VOR gain and the motor Unified Parkinson Disease Rating Scale score. No correlation of VOR gain with age, duration of disease or the Hoehn and Yahr Scale score was observed. VOR gains in PD patients were found to be higher than normal, especially in the early stages of the disease. vHIT is a potential tool to determine the VOR gain in PD patients and may help detect PD at an early stage.