Disinhibited Blink Reflex Recovery Is Related to Lateral Trunk Flexion in Parkinson Disease.

Purpose: Lateral trunk flexion is often observed in patients with Parkinson disease (PD) and causes poor quality of life. Asymmetrical function of the basal ganglia is believed to be the main cause of lateral trunk flexion, and dysfunction of the basal ganglia facilitates the blink reflex by disinhibiting the spinal trigeminal nucleus. Our aim was to investigate whether a disinhibited blink reflex recovery curve (BRrc) was associated with lateral trunk flexion in PD patients. Methods: We enrolled 21 PD patients, including 11 with marked lateral trunk flexion (F-PD) and 10 with normal posture (N-PD), and 10 normal controls. Blink reflex recovery curves at interstimulus intervals of 200, 300, and 500 ms were compared between F-PD, N-PD, and normal controls. Results: The BRrc in F-PD patients was more disinhibited than in N-PD patients and controls, and this disinhibition was asymmetrical. Conclusions: The asymmetrically disinhibited BRrc in F-PD patients was associated with lateral trunk flexion. This is the first neurophysiological study of patients with PD with abnormal posture. Examination of the BRrc may permit early detection of asymmetrical basal ganglia dysfunction that can eventually cause lateral trunk flexion.