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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  • G90.1—

    Familial dysautonomia [Riley-Day]

  • G90.2—

    Horner's syndrome

  • G90.3—

    Multi-system degeneration of the autonomic nervous system

  • G90.4—

    Autonomic dysreflexia

  • G90.50—

    Complex regional pain syndrome I, unspecified

  • G90.511—

    Complex regional pain syndrome I of right upper limb

  • G90.512—

    Complex regional pain syndrome I of left upper limb

  • G90.513—

    Complex regional pain syndrome I of upper limb, bilateral

  • G90.519—

    Complex regional pain syndrome I of unspecified upper limb

  • G90.521—

    Complex regional pain syndrome I of right lower limb

  • G90.522—

    Complex regional pain syndrome I of left lower limb

  • G90.523—

    Complex regional pain syndrome I of lower limb, bilateral

  • G90.529—

    Complex regional pain syndrome I of unspecified lower limb

  • G90.59—

    Complex regional pain syndrome I of other specified site

  • G90.81—

    Serotonin syndrome

  • G90.89—

    Other disorders of autonomic nervous system

  • G90.9—

    Disorder of the autonomic nervous system, unspecified

  • G90.A—

    Postural orthostatic tachycardia syndrome [POTS]

  • G90.B—

    LMNB1-related autosomal dominant leukodystrophy

  • G91.0—

    Communicating hydrocephalus

  • G91.1—

    Obstructive hydrocephalus

  • G91.2—

    (Idiopathic) normal pressure hydrocephalus

  • G91.3—

    Post-traumatic hydrocephalus, unspecified

  • G91.4—

    Hydrocephalus in diseases classified elsewhere

  • G91.8—

    Other hydrocephalus

  • G91.9—

    Hydrocephalus, unspecified

  • G92.00—

    Immune effector cell-associated neurotoxicity syndrome, grade unspecified

  • G92.01—

    Immune effector cell-associated neurotoxicity syndrome, grade 1

  • G92.02—

    Immune effector cell-associated neurotoxicity syndrome, grade 2

  • G92.03—

    Immune effector cell-associated neurotoxicity syndrome, grade 3

  • G92.04—

    Immune effector cell-associated neurotoxicity syndrome, grade 4

  • G92.05—

    Immune effector cell-associated neurotoxicity syndrome, grade 5

  • G92.8—

    Other toxic encephalopathy

  • G92.9—

    Unspecified toxic encephalopathy

  • G93.0—

    Cerebral cysts

  • G93.1—

    Anoxic brain damage, not elsewhere classified

  • G93.2—

    Benign intracranial hypertension

  • G93.31—

    Postviral fatigue syndrome

  • G93.32—

    Myalgic encephalomyelitis/chronic fatigue syndrome

  • G93.39—

    Other post infection and related fatigue syndromes

  • G93.40—

    Encephalopathy, unspecified

  • G93.41—

    Metabolic encephalopathy

  • G93.42—

    Megalencephalic leukoencephalopathy with subcortical cysts

  • G93.43—

    Leukoencephalopathy with calcifications and cysts

  • G93.44—

    Adult-onset leukodystrophy with axonal spheroids

  • G93.45—

    Developmental and epileptic encephalopathy

  • G93.49—

    Other encephalopathy

  • G93.5—

    Compression of brain

  • G93.6—

    Cerebral edema

  • G93.7—

    Reye's syndrome

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