Assessment of vestibulo-ocular reflex function in people with Parkinson’s disease: a cross-sectional study in a rehabilitation setting using the video head impulse test

Background: Parkinson's disease (PD) is a neurodegenerative, progressive disorder known for motor and non-motor symptoms. The vestibular system, via the vestibulo-ocular reflex (VOR), is crucial for maintaining dynamic gaze stability, and its role in PD is raising interest among researchers. Indeed, vestibular dysfunction in PD may exacerbate postural instability and gait disturbances; however, the prevalence of vestibular dysfunctions remains unclear. This study aims to objectively investigate the VOR function in people with PD using the video head impulse test. Methods: This is a cross-sectional study conducted in a neurorehabilitation hospital. People with PD were included if they had no cognitive impairment and the ability to walk without physical assistance. The video head impulse test was used to assess the VOR function across all six semicircular canals, using both the Head Impulse Paradigm (HIMP) and the Suppression Head Impulse Paradigm (SHIMP) paradigms. Results: 35 people with PD (mean age: 69.9±8.4; 11 females) with moderate motor symptoms (MDS-UPDRS-part III: 27.7±6.8) were included. Using normative cut-offs, 69% of the participants had at least one dysfunctional canal (60% hypo-gain, 9% hyper-gain). The prevalence reached 83% when both the HIMP and SHIMP paradigms were considered. Conclusion: There is a high prevalence of vestibular dysfunction in people with PD. The instrumental assessment of VOR gains could reveal undiagnosed vestibular dysfunctions and, in the future, lead to more specific rehabilitation management of people with PD.