A81
Atypical virus infections of central nervous system
A81 is a non-billable ICD-10-CM code category for atypical virus infections of central nervous system. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are A81.0 Creutzfeldt-Jakob disease, A81.1 Subacute sclerosing panencephalitis, A81.2 Progressive multifocal leukoencephalopathy, A81.8 Other atypical virus infections of central nervous system and 1 more. Its coding notes include a Use additional code instruction, 3 Excludes1 entries and 5 Excludes2 entries.
Use additional code
Add the listed code as a secondary code, if known.
- code, if applicable, to identify:
- dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
- dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
- dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
- dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
- dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
- mild neurocognitive disorder due to known physiological condition (F06.7-)
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (5 notes)
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- 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)
Includes
Further defines or gives examples of the content of the category.
- diseases of the central nervous system caused by prions
Also from chapter/block level (1 note)
- diseases generally recognized as communicable or transmissible