The Vestibulo-Ocular Reflex is Associated With Visuospatial Dysfunction in Patients With Parkinson's Disease

Visuospatial impairment is one of the most frequent cognitive deficits in patients with Parkinson's disease (PD). It remains unknown whether the vestibulo-ocular reflex (VOR) function affects visuospatial perception and memory in patients with PD.

To delineate the relationship between VOR and visuospatial function in patients with PD.

We prospectively evaluated video head-impulse tests in 151 patients with PD (mean age $\pm$ standard deviation, 68 $\pm$ 9 years; 77 male). All patients conducted the Rey Complex Figure test (RCFT).

RCFT-copying and RCFT-delayed recall were impaired in 11 (11/151, 7%) and 15 (15/151, 10%) patients, respectively. The VOR gain was normal in 55 patients with PD (55/151, 36%). However, 69 patients overestimated VOR gain for at least one canal, and 34 patients showed a decreased gain for at least one canal (seven patients showed an overestimated gain for some canals and decreased gain for other canals). Multivariable logistic regression analysis showed that abnormal RCFT-copying was negatively associated with the VOR gain for the horizontal canal (odds ratio [OR]: 0.001, 95% confidence interval [CI]: 0.001-0.08, p = 0.007). In contrast, abnormal RCFT-delayed recall was negatively associated with Mini-Mental State Examination scores (0.70, 0.52-0.93, p = 0.013), positively with age (1.11, 1.00-1.22, p = 0.041), male sex (12.82, 1.17-142.86, p = 0.036), years of schooling (1.41, 1.09-1.82, p = 0.009), but not with the VOR gain for any canal.

The VOR function may be associated with deficits in visuospatial perception and learning in patients with PD. This implicates the development of more targeted therapeutic interventions and offers insights into the broader implications of PD on sensory-motor integration and cognitive function.