Unusual dyskinesia complicating cardiopulmonary bypass surgery.

Four infants developed dyskinesia after cardiopulmonary bypass surgery three to four days postoperatively. The dyskinesia was choreoathetotic, and involved mainly the mouth, tongue and face. It was absent during sleep. Three of these infants improved over periods of several weeks, but one infant remained dyskinetic one year postoperatively. Neuro-imaging studies and EEGs were of little value in determining the cause of the dyskinesia. The factors responsible for the involuntary movements and for their severity remain unexplained.