athetosis

athetosis - A disorder of the nervous system that is characterized by slow, writhing, involuntary movements, most often of the face, head, neck, and limbs. These movements commonly include facial grimacing, with contortions of the mouth.

There may also be difficulty in balancing and walking. Athetosis tends to be combined with chorea (jerky involuntary movements). Both athetosis and chorea arise from damage to the basal ganglia, clusters of nerve cells in the brain that control movement.

Causes of athetosis include brain damage prior to or at birth (see cerebral palsy), encephalitis (brain infection), degenerative disorders such as Huntington’s disease, or as a side effect of phenothiazine drugs or levodopa.