Quantitative study of spontaneous eye blinks and eye tics in Gilles de la Tourette's syndrome

Spontaneous eye blink rate and frequency of eye ties were studied in nine T ourette patients during periods of rest, conversation, and video watching. In comparison with controls, the Tourette patients showed a significantly h igher blink rate during rest and video watching. Conversation induced a sig nificant increase in blink rate in the control group, but not in the Touret te patients, whereas video watching significantly increased blink rate in b oth groups. The frequency of eye ties showed a significant decrease during conversation and increased significantly during video watching in Tourette patients. In five patients, a significant positive correlation between blin k rate and eye tic frequency was found, whereas one patient showed a signif icant negative correlation. Our results show that, even though some of our patients were on neuroleptic treatment, blink rate was about twofold to thr eefold increased versus healthy controls, suggesting increased central dopa minergic activity. Furthermore, these first quantitative data illustrate ta sk specific effects on eye tic frequency and the complexity of their relati on with eye blinks.