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ICD-10-CM 2027 diagnosis code

A81.1Subacute sclerosing panencephalitis

✓ Billable / specificCC — complication/comorbidity

A81.1 is a valid, billable ICD-10-CM code for subacute sclerosing panencephalitis. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Panencephalitis, ICD-10 code for Dawson's encephalitis, ICD-10 code for Bodechtel-Guttman disease, ICD-10 code for Van Bogaert's leukoencephalopathy.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About A81.1

A81.1 is the ICD-10-CM diagnosis code for subacute sclerosing panencephalitis. It belongs to category A81 (atypical virus infections of central nervous system), block A80-A89 (viral and prion infections of the central nervous system) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within A81 (atypical virus infections of central nervous system), A81.1 is specifically for subacute sclerosing panencephalitis. Related codes cover Creutzfeldt-Jakob disease (A81.0), progressive multifocal leukoencephalopathy (A81.2), other atypical virus infections of central nervous system (A81.8) and atypical virus infection of central nervous system, unspecified (A81.9).

Use an additional 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) and 1 more.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 056 (Degenerative Nervous System Disorders with MCC, relative weight 2.2655), DRG 057 (Degenerative Nervous System Disorders without MCC, relative weight 1.2838), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), in MDC 01 (Diseases and Disorders of the Nervous System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 046.2 (subacute sclerosing panencephalitis).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Dawson's inclusion body encephalitis
  • Van Bogaert's sclerosing leukoencephalopathy

Notes that apply from higher levels

Instructions written at a parent level also apply to A81.1.

› From A81 Atypical virus infections of central nervous system
Includes
  • diseases of the central nervous system caused by prions
Use additional code

Broader instructions also apply from A80-A89 Viral and prion infections of the central nervous system and Chapter 1: Certain infectious and parasitic diseases.

Alphabetic index entries

13 entries

Terms in the official ICD-10-CM index that lead to A81.1.

Codes whose notes reference A81.1

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

MDC 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

ICD-9-CM equivalent

Converter →
  • 046.2Subacute sclerosing panencephalitisexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about A81.1

Is A81.1 billable?

Yes. A81.1 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can A81.1 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict A81.1 as a principal diagnosis.

Is A81.1 a CC or MCC?

A81.1 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does A81.1 group to?

A81.1 is used in the MS-DRG v44.0 logic for MS-DRG 056 (Degenerative Nervous System Disorders with MCC), MS-DRG 057 (Degenerative Nervous System Disorders without MCC), MS-DRG 791 (Prematurity with Major Problems) and MS-DRG 793 (Full Term Neonate with Major Problems). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for A81.1?

The CMS General Equivalence Mappings map A81.1 to ICD-9-CM 046.2.