All ICD10 Codes
Chapter 6

G00–G99: Diseases of the Nervous System

Diseases of the Nervous System diagnostic classification updated for 2026.

Chapter Instructions

Excludes2(Not included here. Code separately if applicable.)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
All CodesBillable Only
Internal Codes
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  • G12.21—

    Amyotrophic lateral sclerosis

  • G12.22—

    Progressive bulbar palsy

  • G12.23—

    Primary lateral sclerosis

  • G12.24—

    Familial motor neuron disease

  • G12.25—

    Progressive spinal muscle atrophy

  • G12.29—

    Other motor neuron disease

  • G12.8—

    Other spinal muscular atrophies and related syndromes

  • G12.9—

    Spinal muscular atrophy, unspecified

  • G13.0—

    Paraneoplastic neuromyopathy and neuropathy

  • G13.1—

    Other systemic atrophy primarily affecting central nervous system in neoplastic disease

  • G13.2—

    Systemic atrophy primarily affecting the central nervous system in myxedema

  • G13.8—

    Systemic atrophy primarily affecting central nervous system in other diseases classified elsewhere

  • G14—

    Postpolio syndrome

  • G20.A1—

    Parkinson's disease without dyskinesia, without mention of fluctuations

  • G20.A2—

    Parkinson's disease without dyskinesia, with fluctuations

  • G20.B1—

    Parkinson's disease with dyskinesia, without mention of fluctuations

  • G20.B2—

    Parkinson's disease with dyskinesia, with fluctuations

  • G20.C—

    Parkinsonism, unspecified

  • G21.0—

    Malignant neuroleptic syndrome

  • G21.11—

    Neuroleptic induced parkinsonism

  • G21.19—

    Other drug induced secondary parkinsonism

  • G21.2—

    Secondary parkinsonism due to other external agents

  • G21.3—

    Postencephalitic parkinsonism

  • G21.4—

    Vascular parkinsonism

  • G21.8—

    Other secondary parkinsonism

  • G21.9—

    Secondary parkinsonism, unspecified

  • G23.0—

    Hallervorden-Spatz disease

  • G23.1—

    Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]

  • G23.2—

    Striatonigral degeneration

  • G23.3—

    Hypomyelination with atrophy of the basal ganglia and cerebellum

  • G23.8—

    Other specified degenerative diseases of basal ganglia

  • G23.9—

    Degenerative disease of basal ganglia, unspecified

  • G24.01—

    Drug induced subacute dyskinesia

  • G24.02—

    Drug induced acute dystonia

  • G24.09—

    Other drug induced dystonia

  • G24.1—

    Genetic torsion dystonia

  • G24.2—

    Idiopathic nonfamilial dystonia

  • G24.3—

    Spasmodic torticollis

  • G24.4—

    Idiopathic orofacial dystonia

  • G24.5—

    Blepharospasm

  • G24.8—

    Other dystonia

  • G24.9—

    Dystonia, unspecified

  • G25.0—

    Essential tremor

  • G25.1—

    Drug-induced tremor

  • G25.2—

    Other specified forms of tremor

  • G25.3—

    Myoclonus

  • G25.4—

    Drug-induced chorea

  • G25.5—

    Other chorea

  • G25.61—

    Drug induced tics

  • G25.69—

    Other tics of organic origin

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