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

Objective: To 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. Methods: Cervical, 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. Results: Rate 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. Conclusions: VEMPs displayed progressive severity of alterations at different stages of PD, with remarkable correlations with presence of postural instability and RBD. Significance: The combined use of VEMPs may provide interesting insights into the pathophysiological mechanisms of PD at the earliest and prodromal stage of the disease. (C) 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.