A 17-year-old boy presented with abnormal involuntary movements of 6 months duration. Examination revealed mask-like facies and dystonia affecting the neck and right upper and lower limbs. He also displayed peculiar flexion-extension flapping movements at his left knee joint. This rhythmic, patterned, repetitive, purposeless movement that occurred multiple times throughout the day was distractible and suggestive of stereotypy (Video 1). A diagnosis of Wilson disease was confirmed through the presence of Kayser-Fleischer rings, low serum ceruloplasmin, chronic liver disease, and characteristic MRI findings (Figure). Stereotypies in Wilson disease are a rare phenomenon and are a type of perseveratory behavior secondary to dysfunction of fronto-cortico-basal ganglia-thalamo-cortical loops.1,2
