Athetosis is the name sometimes given to an involuntary movement disorder characterized by slow, sinuous, purposeless, writhing movements, often more evident in the distal part of the limbs. Athetosis often coexists with the more flowing, dance-like movements of chorea, in which case the movement disorder may be described as choreoathetosis. Indeed the term athetosis is now little used except in the context of "athetoid cerebral palsy." Athetoid-like movements of the outstretched hands may also been seen in the presence of sensory ataxia (impaired proprioception) and are known as pseudoathetosis or pseudochoreoathetosis.
Choreoathetoid movements result from disorders of the basal ganglia.
Pearce JMS. Athetosis and William Alexander Hammond, a founder of American neurology. In: Pearce JMS. Fragments of neurological his-tory. London: Imperial College Press, 2003: 413-416