Table 2.1.

Classification of dystonia

Age of onset

Early onset (<20 years)

Late onset (>20 years)

Distribution

Focal: single body region (e.g., cervical dystonia, blepharospasm, oromandibular dystonia, spasmodic dysphonia, and task-specific dystonias)

Segmental: contiguous regions (e.g., cranial + cervical)

Multifocal: non-contiguous regions (e.g., cervical + leg)

Generalized: leg + trunk + one other body part

Hemidystonia: ipsilateral arm + leg

Etiology

Primary dystonia: syndromes in which dystonia is the sole phenotypic manifestation with the exception that tremor can be present as well

Secondary dystonia: due to structural lesions, neural insults, or medications (e.g., stroke, trauma, encephalitis, etc.)

Dystonia plus: dystonia plus another movement disorder without overt evidence of neurodegeneration (dopa-responsive dystonia [DRD/DYT5a and DYT5b], myoclonus-dystonia syndrome [MDS/DYT11], rapid-onset dystonia–parkinsonism [RDP/DYT12], and early-onset dystonia with parkinsonism [DYT16])

Heredodegenerative diseases with dystonia: dystonia may be a prominent feature (e.g., X-linked dystonia–parkinsonism [DYT3], progressive supranuclear palsy [PSP], Parkinson’s disease, multiple system atrophy, corticobasal ganglionic degeneration, spinocerebellar ataxia type 3 [SCA3])

Paroxysmal dyskinesias: sudden episodes of involuntary movement, dystonia is often a major clinical feature

Psychogenic dystonia: dystonia is primarily due to psychological factors

Pseudodystonia: dystonia mimics associated with abnormal postures