Abstract
We described the involuntary movement [blepharoclonus (BC)] in five patients with severe physical and mental handicaps. BC was the clonic movement observed on bilateral eyelids as if blinking quickly and repeatedly; it was induced by protruding an examiner's hand suddenly in front of the patient's face, and lasted about one second or more, but neither by auditory, photic or painful stimuli nor by slow protrusion of the hand. BC became difficult to be elicited by repeating the above maneuver.
During BC, surface electromyogram revealed bilaterally synchronized regular clonic contractions (12-13 Hz) on the orbicularis oculi muscle, but showed no activity on the orbicularis oris. CT scanning of the brain revealed parietotemporal low density or atrophy in all patients, and gyral abnormality was suspected in three patients. Blink reflex demonstrated the delay in the latency of the late component in two patients, and that of the early one with marked laterality in one patient.
BC seemed to be one of the startle reflexes, but may not be a simple reflex. It was suggested that BC is elicited via higher cortical functions (such as recognition) followed by the activation of some lower neuronal circuits.
