Blepharospasm (BSP) is a rather distressing form of focal dystonia. Although 
many aspects of its pathophysiological mechanisms are already known, we lack 
fundamental evidence on etiology, prevention, and treatment. To advance in our 
knowledge, we need to review what is already known in various aspects of the 
disorder and use these bases to find future lines of interest. Some of the signs 
observed in BSP are cause, while others are consequence of the disorder. 
Non-motor symptoms and signs may be a cue for understanding better the disease. 
Various cerebral sites have been shown to be functionally abnormal in BSP, 
including the basal ganglia, the cortex, and the cerebellum. However, we still 
do not know if the dysfunction or structural change affecting these brain 
regions is cause or consequence of BSP. Further advances in neurophysiology and 
neuroimaging may eventually clarify the pathophysiological mechanisms 
implicated. In this manuscript, we aim to update what is known regarding 
epidemiology, clinical aspects, and pathophysiology of the disorder and 
speculate on the directions of research worth pursuing in the near future.