Blinking in patients with clinically probable multiple system atrophy

Clinical studies in patients with MSA document facial motor abnormalities, but no studies have objectively assessed blinking abnormalities in this condition.

We enrolled patients diagnosed as having clinically probable MSA, 20 patients of the parkinsonian phenotype (MSA-P) and 10 patients of the cerebellar phenotype (MSA-C) and 20 healthy controls (HCs). Blinking was recorded with a three-dimensional optoelectronic motion system equipped with dedicated software for data analysis.

During voluntary blinking, the interphase pause duration between the closing and opening phases lasted longer in MSA-P and in MSA-C patients than in HCs; the opening phase had increased duration and reduced peak velocity in MSA-P. During reflex blinking, the opening blink phase also lasted longer in MSA-P patients than in HCs. During spontaneous blinking, the rate and kinematics of the closing and opening blinking phases were lower in MSA-P and in MSA-C patients than in HCs. Blink reflex recovery was higher in patients than in HCs. No difference was found between MSA-P patients receiving or not receiving dopaminergic medication.

Our objective assessment of upper facial movement documents abnormalities of voluntary, spontaneous, and reflex blinking in patients with MSA-P and MSA-C, reflecting cortical-basal ganglia and brainstem dysfunction.