Analysis of blink rate in patients with blepharospasm.

The blink rate (BR) during rest, conversation, and reading was assessed in 50 patients with blepharospasm (BS) and in 150 healthy subjects. BR at rest and during conversation was higher in patients with BS. Moreover, 76% of patients had BR higher at rest than during conversation, whereas in 74% of controls, BR was higher during conversation than at rest. The sensitivity and specificity of two parameters (value of BR at rest and pattern rest-BR higher than conversation-BR) in discriminating patients and controls were computed. The best fit was obtained with a rest-BR above 27 blinks per minute. When the two parameters were combined (rest-BR above 27 blinks per minute together with the pattern rest-BR higher than conversation-BR), we obtained a 92.3% sensitivity and a 82.0% specificity in discriminating between BS patients and controls. These findings indicate that specific features of BR can be associated with BS, suggesting that the analysis of BR might be helpful for the diagnosis of BS in early stages.