A81

Non-Billable

ChapterA00–B99

Rankcategory

Official Description

Atypical virus infections of central nervous system

Use a more specific code (3 billable, 2 non-billable)

A81.0Creutzfeldt-Jakob diseasehas subcodes A81.1Subacute sclerosing panencephalitis A81.2Progressive multifocal leukoencephalopathy A81.8Other atypical virus infections of central nervous systemhas subcodes A81.9Atypical virus infection of central nervous system, unspecified

Metadata & Insights

•Non-billable category (requires more specific sub-code).
•Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99).

CH1 Parent Instructions

Includes

diseases generally recognized as communicable or transmissible

Excludes1(Not coded here. Use a different code.)

certain localized infections - see body system-related chapters

Excludes2(Not included here. Code separately if applicable.)

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

code to identify resistance to antimicrobial drugs (Z16.-)

A80-A89 Parent Instructions

Excludes1(Not coded here. Use a different code.)

postpolio syndrome (G14)
sequelae of poliomyelitis (B91)
sequelae of viral encephalitis (B94.1)

Instructional Notes

Includes

diseases of the central nervous system caused by prions

Use Additional Code

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-)

Clinical Hierarchy

BillableHas subcodes

CH1Certain infectious and parasitic diseases (A00-B99)

A80-A89Viral and prion infections of the central nervous system (A80-A89)

A81Atypical virus infections of central nervous systemNot billable

A81.0Creutzfeldt-Jakob diseaseSubcodes

A81.1Subacute sclerosing panencephalitisBillable

A81.2Progressive multifocal leukoencephalopathyBillable

A81.8Other atypical virus infections of central nervous systemSubcodes

A81.9Atypical virus infection of central nervous system, unspecifiedBillable

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to A81:

blockA80-A89

Viral and prion infections of the central nervous system (A80-A89)

View context instructions

chapterCH1

Certain infectious and parasitic diseases (A00-B99)

View context instructions

MS-DRG Classification

2026

No direct MS-DRG triggers identified.

Cross Reference

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