Paired neurophysiological and clinical study of the brainstem at different stages of Parkinson's Disease

•In comparison with matched controls, VEMPs were consistently altered in patients with Parkinson's Disease (PD) and severity of abnormalities progressively increased with stage of disease.•In PD significant correlation was found between VEMP alterations and both postural instability and REM sleep behavior disorder.•Combined use of VEMPs may provide insights into pathophysiological dynamics of brainstem involvement at the earliest phases of PD.

ObjectiveTo study brainstem function in Parkinson's Disease (PD) at different stages, through a battery of vestibular-evoked myogenic potentials (VEMPs) and compare the results with scores on clinical scales assessing the presence of symptoms linked to brainstem involvement.MethodsCervical, masseter and ocular VEMPs were recorded in patients with early PD (n = 14, disease duration 1.42 ± 0.7 years), advanced PD (n = 19, disease duration 7.26 ± 2.9 years) and in 27 age-matched controls. In PD, the following clinical scales were administered: Mini-BESTest, REM sleep Behavior Disorder Screening Questionnaire (RBD-SQ), PD Sleep Scale, Epworth Sleepiness Scale and Geriatric Depression Scale.ResultsRate of VEMPs alterations was higher (p < 0.001) in PD than controls, but similar within PD groups. However, early and advanced PD showed a different pattern of abnormalities (p = 0.02), being latency delay prevalent in the former and absence in the latter. VEMP impairment correlated directly with RBD-SQ scores in both PD cohorts and inversely with Mini-BESTest scores in advanced PD.ConclusionsVEMPs displayed progressive severity of alterations at different stages of PD, with remarkable correlations with presence of postural instability and RBD.SignificanceThe combined use of VEMPs may provide interesting insights into the pathophysiological mechanisms of PD at the earliest and prodromal stage of the disease.