1. ICD-10-CM Codes
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2. A00-B99
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3. A80-A89
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4. A81-
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5. 2023 ICD-10-CM Diagnosis Code A81.9

2023 ICD-10-CM Diagnosis Code A81.9

Atypical virus infection of central nervous system, unspecified

2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

• A81.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
• Short description: Atypical virus infection of central nervous system, unsp
• The 2023 edition of ICD-10-CM A81.9 became effective on October 1, 2022.
• This is the American ICD-10-CM version of A81.9 - other international versions of ICD-10 A81.9 may differ.

• Prion disease
• Prion disease of central nervous system
• Slow viral central nervous system infection
• Slow virus infection of central nervous system

• A group of genetic, infectious, or sporadic degenerative human and animal nervous system disorders associated with abnormal prions. These diseases are characterized by conversion of the normal prion protein to an abnormal configuration via a post-translational process. In humans, these conditions generally feature dementia; ataxia; and a fatal outcome. Pathologic features include a spongiform encephalopathy without evidence of inflammation. The older literature occasionally refers to these as unconventional slow virus diseases. (from proc natl acad sci usa 1998 nov 10;95(23):13363-83)
• Any of various brain diseases in humans and animals in which areas of the brain slowly degenerate and take on a spongy appearance.
• Prion diseases, also termed transmissible spongiform encephalopathies (tses), are a group of fatal neurodegenerative diseases that affect humans and a number of other animal species. The etiology of these diseases is thought to be associated with the conversion of a normal protein, prpc, into an infectious, pathogenic form, prpsc. The conversion is induced by prion infections (for example, variant creutzfeldt-jakob disease (vcjd), iatrogenic cjd, kuru), mutations (familial cjd, gerstmann-straussler-scheinker syndrome, fatal familial insomnia (ffi)) or unknown factors (sporadic cjd (scjd)), and is thought to occur after prpc has reached the plasma membrane or is re-internalized for degradation. The prpsc form shows greater protease resistance than prpc and accumulates in affected individuals, often in the form of extracellular plaques. Pathways that may lead to neuronal death comprise oxidative stress, regulated activation of complement, ubiquitin-proteasome and endosomal-lysosomal systems, synaptic alterations and dendritic atrophy, corticosteroid response, and endoplasmic reticulum stress. In addition, the conformational transition could lead to the lost of a beneficial activity of the natively folded protein, prpc.

• 056 Degenerative nervous system disorders with mcc
• 057 Degenerative nervous system disorders without mcc
• 974 Hiv with major related condition with mcc
• 975 Hiv with major related condition with cc
• 976 Hiv with major related condition without cc/mcc

Convert A81.9 to ICD-9-CM

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change

• Code First: F02
  ICD-10-CM Diagnosis Code F02

  Dementia in other diseases classified elsewhere

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Code First

  • the underlying physiological condition, such as:
  • Alzheimer's (G30.-)
  • cerebral lipidosis (E75.4)
  • Creutzfeldt-Jakob disease (A81.0-)
  • dementia with Lewy bodies (G31.83)
  • dementia with Parkinsonism (G31.83)
  • epilepsy and recurrent seizures (G40.-)
  • frontotemporal dementia (G31.09)
  • hepatolenticular degeneration (E83.0)
  • human immunodeficiency virus [HIV] disease (B20)
  • Huntington's disease (G10)
  • hypercalcemia (E83.52)
  • hypothyroidism, acquired (E00-E03.-)
  • intoxications (T36-T65)
  • Jakob-Creutzfeldt disease (A81.0-)
  • multiple sclerosis (G35)
  • neurosyphilis (A52.17)
  • niacin deficiency [pellagra] (E52)
  • Parkinson's disease (G20)
  • Pick's disease (G31.01)
  • polyarteritis nodosa (M30.0)
  • prion disease (A81.9)
  • systemic lupus erythematosus (M32.-)
  • traumatic brain injury (S06.-)
  • trypanosomiasis (B56.-, B57.-)
  • vitamin B deficiency (E53.8)

  Includes

  • Major neurocognitive disorder in other diseases classified elsewhere

  Type 1 Excludes

  • mild neurocognitive disorder due to known physiological condition with or without behavioral disturbance (F06.7-)

  Type 2 Excludes

  • dementia in alcohol and psychoactive substance disorders (F10-F19, with .17, .27, .97)
  • vascular dementia (F01.5-, F01.A-, F01.B-, F01.C-)

• Disease, diseased - see also Syndrome
  • prion, central nervous system A81.9
• Infection, infected, infective (opportunistic) B99.9
  ICD-10-CM Diagnosis Code B99.9

  Unspecified infectious disease

  2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
  • atypical
    • virus A81.9
  • slow virus A81.9
  • virus, viral NOS B34.9
    ICD-10-CM Diagnosis Code B34.9

    Viral infection, unspecified

    2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

    Applicable To

    • Viremia NOS
    • central nervous system A89
      ICD-10-CM Diagnosis Code A89

      Unspecified viral infection of central nervous system

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
      • atypical A81.9
      • slow virus A81.9
    • slow A81.9

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.