Gilles Lyon, MD
Dystonia consist of slow sustained, irregular, twisting (torsional) movements or muscle spasms interspersed with more rapid involuntary movements or jerks. The slow, sinuous, purposeless movements predominating in hands, feet, face and tongue of athetosis or choreo-athetosis (when brisk involuntary movements are also present) are closely allied with extrapyramidal (basal ganglia) disorders. Dystonia and athetosis have been used almost interchangeably in the literature; the term dystonia is now generally preferred.
NOTE: Dystonia must be distinguished from ataxia.