Voluntary, spontaneous, and reflex blinking in Parkinson's disease.
Blinking, a motor act consisting of a closing and an opening eyelid movement, can be performed voluntarily, spontaneously, and reflexly. In this study we investigated the kinematic features of voluntary, spontaneous, and reflex blinking in patients with Parkinson's disease (PD), OFF and ON dopaminergic treatment. Patients were asked to blink voluntarily as fast as possible. Spontaneous blinking was recorded for a minute during which the subjects just relaxed. Reflex blinking was evoked by electrical stimulation on the supraorbital nerve. Eyelid movements were recorded with the SMART analyzer motion system. Patients OFF therapy paused longer than controls during voluntary blinking but not during spontaneous and reflex blinking. The blink rate tended to be lower in patients OFF therapy than in controls and the spontaneous blinking had abnormally low amplitude and peak velocity. Finally, in patients OFF therapy the excitability of the neural circuit mediating the closing phase of the reflex blinking was enhanced. Dopaminergic treatment shortened the pause during voluntary blinking and increased the blink rate. In PD patients the longer pauses between the closing and opening phase in comparison to normal subjects, suggest bradykinesia of voluntary blinking. PD patients also display kinematic abnormalities of spontaneous blinking and changes in the excitability of the closing phase of reflex blinking.
Agostino
Rocco
R
Department of Neurological Sciences, Sapienza University of Rome, Rome, Italy.
Bologna
Matteo
M
Dinapoli
Loredana
L
Gregori
Bruno
B
Fabbrini
Giovanni
G
Accornero
Neri
N
Berardelli
Alfredo
A
D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001696:Biomechanical Phenomena; D001767:Blinking / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy / Q000503:physiopathology*; D011930:Reaction Time; D012016:Reference Values; D014836:Volition
D000978:Antiparkinson Agents; D007980:Levodopa