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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  • G45.3—

    Amaurosis fugax

  • G45.4—

    Transient global amnesia

  • G45.8—

    Other transient cerebral ischemic attacks and related syndromes

  • G45.9—

    Transient cerebral ischemic attack, unspecified

  • G46.0—

    Middle cerebral artery syndrome

  • G46.1—

    Anterior cerebral artery syndrome

  • G46.2—

    Posterior cerebral artery syndrome

  • G46.3—

    Brain stem stroke syndrome

  • G46.4—

    Cerebellar stroke syndrome

  • G46.5—

    Pure motor lacunar syndrome

  • G46.6—

    Pure sensory lacunar syndrome

  • G46.7—

    Other lacunar syndromes

  • G46.8—

    Other vascular syndromes of brain in cerebrovascular diseases

  • G47.00—

    Insomnia, unspecified

  • G47.01—

    Insomnia due to medical condition

  • G47.09—

    Other insomnia

  • G47.10—

    Hypersomnia, unspecified

  • G47.11—

    Idiopathic hypersomnia with long sleep time

  • G47.12—

    Idiopathic hypersomnia without long sleep time

  • G47.13—

    Recurrent hypersomnia

  • G47.14—

    Hypersomnia due to medical condition

  • G47.19—

    Other hypersomnia

  • G47.20—

    Circadian rhythm sleep disorder, unspecified type

  • G47.21—

    Circadian rhythm sleep disorder, delayed sleep phase type

  • G47.22—

    Circadian rhythm sleep disorder, advanced sleep phase type

  • G47.23—

    Circadian rhythm sleep disorder, irregular sleep wake type

  • G47.24—

    Circadian rhythm sleep disorder, free running type

  • G47.25—

    Circadian rhythm sleep disorder, jet lag type

  • G47.26—

    Circadian rhythm sleep disorder, shift work type

  • G47.27—

    Circadian rhythm sleep disorder in conditions classified elsewhere

  • G47.29—

    Other circadian rhythm sleep disorder

  • G47.30—

    Sleep apnea, unspecified

  • G47.31—

    Primary central sleep apnea

  • G47.32—

    High altitude periodic breathing

  • G47.33—

    Obstructive sleep apnea (adult) (pediatric)

  • G47.34—

    Idiopathic sleep related nonobstructive alveolar hypoventilation

  • G47.35—

    Congenital central alveolar hypoventilation syndrome

  • G47.36—

    Sleep related hypoventilation in conditions classified elsewhere

  • G47.37—

    Central sleep apnea in conditions classified elsewhere

  • G47.39—

    Other sleep apnea

  • G47.411—

    Narcolepsy with cataplexy

  • G47.419—

    Narcolepsy without cataplexy

  • G47.421—

    Narcolepsy in conditions classified elsewhere with cataplexy

  • G47.429—

    Narcolepsy in conditions classified elsewhere without cataplexy

  • G47.50—

    Parasomnia, unspecified

  • G47.51—

    Confusional arousals

  • G47.52—

    REM sleep behavior disorder

  • G47.53—

    Recurrent isolated sleep paralysis

  • G47.54—

    Parasomnia in conditions classified elsewhere

  • G47.59—

    Other parasomnia

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