Latencies of vagus sensory evoked potentials are prolonged in Parkinson's disease

Introduction: Although Parkinson's disease (PD) presents principally as a movement disorder, involvement of brainstem nuclei such as the dorsal nucleus of the vagal nerve is well established. Vagus nerve function may be assessed, in part, by recording somatosensory evoked potentials (VSEP) after stimulation of its auricular branch (Fallgatter 2003).

Methods: Vagus nerve somatosensory evoked potentials (VSEP) were investigated in 22 patients with PD (age 66.8±10.0, 7 females) and 22 age- and sex-matched controls. Far field potentials were recorded from electrodes positioned at C3, C4, F3, F4 and Fz after transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve. VSEP were elicited using 100 stimuli (stimulation duration 0.1ms, frequency 0.5Hz) and the following montages: C3-F3, Fz-F3 (left vagus nerve), and C4-F4, Fz-F4 (right vagus nerve). Peak latencies of early components (P1, N1, P2) and peak-to-peak amplitudes (P1-N1, N1-P2) were determined.

Results: VSEP were present with identifiable peaks P1, N1, and P2 in all patients and controls. Peak latencies were significantly longer in PD patients compared to a healthy control group (ANOVA, F=39.620, p<0.001). No significant differences of peak-to-peak amplitudes were found between both groups (p=0.285).

Conclusions: Prolonged VSEP latencies may indicate dysfunction of the brainstem nuclei of the vagus nerve in PD.