2020 ICD-10-CM Diagnosis Code A81.9

Atypical virus infection of central nervous system, unspecified

    2016 2017 2018 2019 2020 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 2020 edition of ICD-10-CM A81.9 became effective on October 1, 2019.
  • This is the American ICD-10-CM version of A81.9 - other international versions of ICD-10 A81.9 may differ.
Applicable To
  • Prion diseases of the central nervous system NOS
The following code(s) above A81.9 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to A81.9:
  • A00-B99
    2020 ICD-10-CM Range A00-B99

    Certain infectious and parasitic diseases

    Includes
    • diseases generally recognized as communicable or transmissible
    Type 1 Excludes
    • certain localized infections - see body system-related chapters
    Type 2 Excludes
    • carrier or suspected carrier of infectious disease (Z22.-)
    • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
    • infectious and parasitic diseases specific to the perinatal period (P35-P39)
    • influenza and other acute respiratory infections (J00-J22)
    Use Additional
    • code to identify resistance to antimicrobial drugs (Z16.-)
    Certain infectious and parasitic diseases
  • A80-A89
    2020 ICD-10-CM Range A80-A89

    Viral and prion infections of the central nervous system

    Type 1 Excludes
    • postpolio syndrome (G14)
    • sequelae of poliomyelitis (B91)
    • sequelae of viral encephalitis (B94.1)
    Viral and prion infections of the central nervous system
  • A81
    ICD-10-CM Diagnosis Code A81

    Atypical virus infections of central nervous system

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Includes
    • diseases of the central nervous system caused by prions
    Use Additional
    • code to identify:
    • dementia with behavioral disturbance (F02.81)
    • dementia without behavioral disturbance (F02.80)
    Atypical virus infections of central nervous system
Approximate Synonyms
  • Prion disease
  • Prion disease of central nervous system
  • Slow viral central nervous system infection
  • Slow virus infection of central nervous system
Clinical Information
  • 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.
ICD-10-CM A81.9 is grouped within Diagnostic Related Group(s) (MS-DRG v37.0):
  • 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

Code History
  • 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
Code annotations containing back-references to A81.9:
  • Code First: F02
    ICD-10-CM Diagnosis Code F02

    Dementia in other diseases classified elsewhere

      2016 2017 2018 2019 2020 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 2 Excludes
    • dementia in alcohol and psychoactive substance disorders (F10-F19, with .17, .27, .97)
    • vascular dementia (F01.5-)

Diagnosis Index entries containing back-references to A81.9:

ICD-10-CM Codes Adjacent To A81.9
A81.00 …… unspecified
A81.01 Variant Creutzfeldt-Jakob disease
A81.09 Other Creutzfeldt-Jakob disease
A81.1 Subacute sclerosing panencephalitis
A81.2 Progressive multifocal leukoencephalopathy
A81.8 Other atypical virus infections of central nervous system
A81.81 Kuru
A81.82 Gerstmann-Sträussler-Scheinker syndrome
A81.83 Fatal familial insomnia
A81.89 Other atypical virus infections of central nervous system
A81.9 Atypical virus infection of central nervous system, unspecified
A82 Rabies
A82.0 Sylvatic rabies
A82.1 Urban rabies
A82.9 Rabies, unspecified
A83 Mosquito-borne viral encephalitis
A83.0 Japanese encephalitis
A83.1 Western equine encephalitis
A83.2 Eastern equine encephalitis
A83.3 St Louis encephalitis
A83.4 Australian encephalitis

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