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)
  • 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
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Internal Codes
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  • G00—

    Bacterial meningitis, not elsewhere classified

  • G00.0—

    Hemophilus meningitis

  • G00.1—

    Pneumococcal meningitis

  • G00.2—

    Streptococcal meningitis

  • G00.3—

    Staphylococcal meningitis

  • G00.8—

    Other bacterial meningitis

  • G00.9—

    Bacterial meningitis, unspecified

  • G01—

    Meningitis in bacterial diseases classified elsewhere

  • G02—

    Meningitis in other infectious and parasitic diseases classified elsewhere

  • G03—

    Meningitis due to other and unspecified causes

  • G03.0—

    Nonpyogenic meningitis

  • G03.1—

    Chronic meningitis

  • G03.2—

    Benign recurrent meningitis [Mollaret]

  • G03.8—

    Meningitis due to other specified causes

  • G03.9—

    Meningitis, unspecified

  • G04—

    Encephalitis, myelitis and encephalomyelitis

  • G04.0—

    Acute disseminated encephalitis and encephalomyelitis (ADEM)

  • G04.00—

    Acute disseminated encephalitis and encephalomyelitis, unspecified

  • G04.01—

    Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

  • G04.02—

    Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis

  • G04.1—

    Tropical spastic paraplegia

  • G04.2—

    Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

  • G04.3—

    Acute necrotizing hemorrhagic encephalopathy

  • G04.30—

    Acute necrotizing hemorrhagic encephalopathy, unspecified

  • G04.31—

    Postinfectious acute necrotizing hemorrhagic encephalopathy

  • G04.32—

    Postimmunization acute necrotizing hemorrhagic encephalopathy

  • G04.39—

    Other acute necrotizing hemorrhagic encephalopathy

  • G04.8—

    Other encephalitis, myelitis and encephalomyelitis

  • G04.81—

    Other encephalitis and encephalomyelitis

  • G04.82—

    Acute flaccid myelitis

  • G04.89—

    Other myelitis

  • G04.9—

    Encephalitis, myelitis and encephalomyelitis, unspecified

  • G04.90—

    Encephalitis and encephalomyelitis, unspecified

  • G04.91—

    Myelitis, unspecified

  • G05—

    Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere

  • G05.3—

    Encephalitis and encephalomyelitis in diseases classified elsewhere

  • G05.4—

    Myelitis in diseases classified elsewhere

  • G06—

    Intracranial and intraspinal abscess and granuloma

  • G06.0—

    Intracranial abscess and granuloma

  • G06.1—

    Intraspinal abscess and granuloma

  • G06.2—

    Extradural and subdural abscess, unspecified

  • G07—

    Intracranial and intraspinal abscess and granuloma in diseases classified elsewhere

  • G08—

    Intracranial and intraspinal phlebitis and thrombophlebitis

  • G09—

    Sequelae of inflammatory diseases of central nervous system

  • G10—

    Huntington's disease

  • G11—

    Hereditary ataxia

  • G11.0—

    Congenital nonprogressive ataxia

  • G11.1—

    Early-onset cerebellar ataxia

  • G11.10—

    Early-onset cerebellar ataxia, unspecified

  • G11.11—

    Friedreich ataxia

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