BACKGROUND: The neurophysiological disruptions underlying blepharospasm, a 
disabling movement disorder characterized by increased blinking and involuntary 
muscle spasms of the eyelid, remain poorly understood.
OBJECTIVE: To investigate the neural substrates underlying reflexive blinking in 
blepharospasm patients compared to healthy controls using simultaneous 
functional MRI and surface electromyography.
METHODS: Fifteen blepharospasm patients and 15 healthy controls were recruited. 
Randomly timed air puffs to the left eye were used to induce reflexive eye 
blinks during two 8-minute functional MRI scans. Continuous surface 
electromyography and video recordings were used to monitor blink responses. 
Imaging data were analyzed using an event-related design.
RESULTS: Fourteen blepharospasm patients (10 female; 61.6 ± 8.0 years) and 15 
controls (11 female; 60.9 ± 5.5 years) were included in the final analysis. 
Reflexive eye blinks in controls were associated with activation of the right 
hippocampus and in patients with activation of the left caudate nucleus. 
Reflexive blinks in blepharospasm patients showed increased activation in the 
right postcentral gyrus and precuneus, left precentral gyrus, and left occipital 
cortex compared to controls. Dystonia severity negatively correlated with 
activity in the left occipital cortex, and disease duration negatively 
correlated with reflexive-blink activity in the cerebellum.
CONCLUSIONS: Reflexive blinking in blepharospasm is associated with increased 
activation in the caudate nucleus and sensorimotor cortices, suggesting a loss 
of inhibition within the sensorimotor corticobasal ganglia network. The 
association between decreasing neural response during reflexive blinking in the 
cerebellum with disease duration suggests an adaptive role. © 2020 International 
Parkinson and Movement Disorder Society.