ABSTRACT
Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonia is a basal ganglia disorder with dysfunction of the basal ganglia–cerebellothalamocortical circuit. Neurophysiological evidence in patients with dystonia has consistently demonstrated reduced inhibitory activity at the cortical, brainstem, and spinal cord levels leading to excessive muscle activation, causing co-contraction and overflow. A valuable starting point in the assessment of dystonia is brain imaging with magnetic resonance imaging, which is normal in the majority of the isolated idiopathic dystonia syndromes and abnormal in many examples of combined dystonia due to secondary structural or specific genetic syndromes. Differentiate isolated from combined dystonia and then classify dystonia based on the age of onset, distribution, and temporal pattern. Paroxysmal dyskinesia is characterized by the occurrence of episodic stereotyped dystonia or chorea or both, without loss of consciousness, variable duration of attacks in which specific triggers can be identified.
