A81 Atypical virus infections of central nervous system

ICD-10-CM Code A81: Atypical Virus Infections of Central Nervous System

ICD-10-CM code A81 designates the diagnostic category for atypical virus infections of the central nervous system. This active code is classified under the broader parent grouping for viral and prion infections of the central nervous system. It represents a disease or syndrome concept without narrower terminology concepts listed in its official record. 1

Plain-language overview

Code A81 identifies a diagnostic category for atypical virus infections of the central nervous system, providing a standardized terminology record for this specific health condition. 1

What this code represents

The official preferred name for A81 is atypical virus infections of central nervous system, and its semantic type is classified as a disease or syndrome. 1

Code A81 is a child concept of the parent grouping A80-A89, which covers viral and prion infections of the central nervous system, and the A81 record lists no narrower concepts. 1

Coding details

Although the A81 terminology record lists no narrower concepts, associated specific codes exist, including A81.0 for Creutzfeldt-Jakob disease and A81.2 for progressive multifocal leukoencephalopathy. 1 2

Additional specific codes under this category include A81.8 for other atypical virus infections of the central nervous system and A81.89, which also carries the disease or syndrome semantic type. 2 3

Documentation considerations

Clinical coding references list labels for other specified and unspecified atypical central nervous system viral infections, providing distinct documentation categories for these diagnostic presentations. 4

Coverage and utilization context

Infectious disease clinical coding references list atypical central nervous system virus infections alongside other nervous system involvement categories, such as Chagas' disease, illustrating varied diagnostic grouping contexts. 4

What the sources add

The official terminology record establishes the active status and parent hierarchy of A81, while the explorer interface provides specific child codes like A81.89 that detail distinct disease presentations. 1 3

While the official terminology record lists no narrower concepts for A81, clinical coding references and explorer interfaces identify multiple specific subcodes, revealing a difference in structural hierarchy presentation. 1 2 4

Sources

1. ICD-10-CM A81 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
3. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
4. Infectious Disease ICD-10 Codes — infectiousdiseaseadvisor.com; accessed 2026-07-27.