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A81 ICD-10-CM Code: Atypical virus infections of central nervous system

A81 isn’t billable on its own. Choose one of the 10 billable codes beneath it, the one the documentation supports.

Official description

A81

Atypical virus infections of central nervous system

ICD-10-CM diagnosis code · United States clinical modification

Billable codes under A81

A81 can’t be reported on its own. Choose the code below that matches what the note documents.

Where A81 sits

  1. 1

    Chapter 1

    Certain infectious and parasitic diseases (A00-B99)

  2. 2

    Section

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

  3. 3

    Category A81

    Atypical virus infections of central nervous system

  4. 4

    Code A81

    Atypical virus infections of central nervous system

Notes for this code

Inclusion terms

No inclusion terms are listed for A81.

Code first

No “code first” instruction is listed for A81.

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-)

Excludes1

Conditions that should not be reported together with this code.

No Excludes1 note is listed for A81.

Excludes2

Conditions not included here that may be reported separately when present.

No Excludes2 note is listed for A81.

Source and release

Data release
U.S. ICD-10-CM · FY 2027
Effective date
Oct 1, 2026

This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.

Review the CDC/NCHS ICD-10-CM source

Frequently asked questions

What does ICD-10-CM code A81 mean?

A81 is the FY 2027 U.S. ICD-10-CM code for “Atypical virus infections of central nervous system.”

Is A81 a billable or specific ICD-10-CM code?

No. A81 has 10 billable codes beneath it in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.

Where is A81 located in ICD-10-CM?

A81 is listed in Chapter 1, Certain infectious and parasitic diseases (A00-B99), within Viral and prion infections of the central nervous system (A80-A89) (A80–A89), under category A81, Atypical virus infections of central nervous system.

What coding notes are listed for A81?

No inclusion terms are listed for A81 in this reference record. No code-first instruction is listed. Additional-code instructions: 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-). No Excludes1 note is listed. No Excludes2 note is listed.