Chapter VI
Diseases of the nervous system
(G00-G99)

Extrapyramidal and movement disorders
(G20-G26)

G20 Parkinson's disease
Hemiparkinsonism
Paralysis agitans
Parkinsonism or Parkinson's disease:
· NOS
· idiopathic
· primary

G21 Secondary parkinsonism
G21.0 Malignant neuroleptic syndrome
Use additional external cause code (Chapter XX), if desired, to identify drug.
G21.1 Other drug-induced secondary parkinsonism
Use additional external cause code (Chapter XX), if desired, to identify drug.
G21.2 Secondary parkinsonism due to other external agents
Use additional external cause code (Chapter XX), if desired, to identify external agent.
G21.3 Postencephalitic parkinsonism
G21.8 Other secondary parkinsonism
G21.9 Secondary parkinsonism, unspecified

G22* Parkinsonism in diseases classified elsewhere
Syphilitic parkinsonism ( A52.1+ )

G23 Other degenerative diseases of basal ganglia
Excludes: multi-system degeneration ( G90.3 )
G23.0 Hallervorden-Spatz disease
Pigmentary pallidal degeneration
G23.1 Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]
G23.2 Striatonigral degeneration
G23.8 Other specified degenerative diseases of basal ganglia
Calcification of basal ganglia
G23.9 Degenerative disease of basal ganglia, unspecified

G24 Dystonia
Includes: dyskinesia
Excludes: athetoid cerebral palsy ( G80.3 )
G24.0 Drug-induced dystonia
Use additional external cause code (Chapter XX), if desired, to identify drug.
G24.1 Idiopathic familial dystonia
Idiopathic dystonia NOS
G24.2 Idiopathic nonfamilial dystonia
G24.3 Spasmodic torticollis
Excludes: torticollis NOS ( M43.6 )
G24.4 Idiopathic orofacial dystonia
Orofacial dyskinesia
G24.5 Blepharospasm
G24.8 Other dystonia
G24.9 Dystonia, unspecified
Dyskinesia NOS

G25 Other extrapyramidal and movement disorders
G25.0 Essential tremor
Familial tremor
Excludes: tremor NOS ( R25.1 )
G25.1 Drug-induced tremor
Use additional external cause code (Chapter XX), if desired, to identify drug.
G25.2 Other specified forms of tremor
Intention tremor
G25.3 Myoclonus
Drug-induced myoclonus
Use additional external cause code (Chapter XX), if desired, to identify drug, if drug-induced.
Excludes: facial myokymia ( G51.4 )
myoclonic epilepsy ( G40.- )
G25.4 Drug-induced chorea
Use additional external cause code (Chapter XX), if desired, to identify drug.
G25.5 Other chorea
Chorea NOS
Excludes: chorea NOS with heart involvement ( I02.0 )
Huntington's chorea ( G10 )
rheumatic chorea ( I02.- )
Sydenham's chorea ( I02.- )
G25.6 Drug-induced tics and other tics of organic origin
Use additional external cause code (Chapter XX), if desired, to identify drug, if drug-induced.
Excludes: de la Tourette's syndrome ( F95.2 )
tic NOS ( F95.9 )
G25.8 Other specified extrapyramidal and movement disorders
Restless legs syndrome
Stiff-man syndrome
G25.9 Extrapyramidal and movement disorder, unspecified

G26* Extrapyramidal and movement disorders in diseases classified elsewhere