2026 ICD-10-CM Diagnosis Code A89Unspecified viral infection of central nervous system
ICD-10-CM Codes›A00–B99›A80-A89›A89
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A89 is a billable ICD-10-CM diagnosis code for unspecified viral infection of central nervous system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 97 through 99, 974 through 976. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 186 closely related codes. Coders also document this condition as viral infection of central nervous system. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified CNS infection and poliomyelitis and Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Viral infection of central nervous system
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Neurologic Diseases
The brain, spinal cord, and nerves make up the nervous system. Together they control all the workings of the body. When something goes wrong with a part of your nervous system, you can have trouble moving, speaking, swallowing, breathing, or learning. You can also have problems with your memory, senses, or mood.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A89 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A89Overview
What is the ICD-10 code for unspecified viral infection of central nervous system?
The ICD-10-CM code for unspecified viral infection of central nervous system is A89. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is A89 (Unspecified viral infection of central nervous system) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified viral infection of central nervous system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does A89 group to?
When unspecified viral infection of central nervous system is the principal diagnosis on an inpatient stay, it groups to MS-DRG 97, 98, 99, 974, 975, 976, with relative weights from 0.8945 to 3.6118 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A89 a CC or MCC?
CMS lists A89 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 186 closely related codes in its exclusion list.
What is the ICD-9 equivalent of A89?
Under the General Equivalence Mappings, unspecified viral infection of central nervous system converts to ICD-9-CM 049.9 (viral encephalitis NOS). The mapping is approximate, so confirm the match fits the documentation.
