Unspecified viral infection of central nervous system
In Viral and prion infections of the central nervous system (A80-A89), chapter 1: Certain Infectious and Parasitic Diseases
- A89 is an unspecified code: use it only when the record doesn't document anything more specific. If the record has more detail, check the other codes under A80-A89 below.
- As a secondary diagnosis it is a CC (complication or comorbidity), which can raise the MS-DRG payment. It doesn't count when the principal diagnosis is one of 186 closely related codes.
- Doesn't count toward a Medicare Advantage risk score (no HCC in V28).
- AHRQ's Chronic Condition Indicator classes it as not chronic (an acute or short-term condition).
Also indexed as: Infection, virus, viral NOS, central nervous system
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Instructional notes
Also applies, from Viral and prion infections of the central nervous system (A80-A89)
These notes sit on A80-A89 and apply to every code under it, including A89.
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Rules for coding infections and parasitic diseases, including HIV, organism and drug resistance codes, sepsis and septic shock, MRSA, Zika, and COVID-19.
- Human Immunodeficiency Virus (HIV) Infections (page 19)
- Infectious agents as the cause of diseases classified to other chapters (page 22)
- Infections resistant to antibiotics (page 22)
- Sepsis, Severe Sepsis, and Septic Shock (page 23)
- Methicillin Resistant Staphylococcus aureus (MRSA) Conditions (page 27)
- Zika virus infections (page 28)
- Coronavirus infections (page 28)
Other codes under A80-A89
Viral and prion infections of the central nervous system (A80-A89)
- A80Acute poliomyelitis
- A81Atypical virus infections of central nervous system
- A82Rabies
- A83Mosquito-borne viral encephalitis
- A84Tick-borne viral encephalitis
- A85Other viral encephalitis, not elsewhere classified
- A86Unspecified viral encephalitis
- A87Viral meningitis
- A88Other viral infections of central nervous system, not elsewhere classified
- A89Unspecified viral infection of central nervous system(this code)
A89 MS-DRGs
As the principal diagnosis, A89 groups to MS-DRG 097, 098, 099, 974, 975, or 976 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 097 Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC
- DRG 098 Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC
- DRG 099 Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC
- DRG 974 HIV with Major Related Condition with MCC
- DRG 975 HIV with Major Related Condition with CC
- DRG 976 HIV with Major Related Condition without CC/MCC
Related conditions
Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.
A89 is in Other specified CNS infection and poliomyelitis (NVS003, its default category), with 31 codes. Others in it:
A89 is in Viral infection (INF008), with 309 codes. Others in it:
Medicare coverage articles listing A89
This Medicare billing and coding article lists A89 as a diagnosis that supports medical necessity for the services they cover. From the CMS Medicare Coverage Database; check your own contractor's article before billing.
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
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 more about neurologic diseases on MedlinePlusViral Infections
Viruses are very tiny germs. They are made of genetic material (either DNA or RNA) inside of a protein coating. There are a huge number of viruses on earth. Only a small number of them can infect humans. Those viruses can infect our cells, which may cause disease. Some of the diseases that viruses can cause include the common cold, the flu, COVID-19, and HIV.
Read more about viral infections on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.
ICD-9-CM equivalent
Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).
- 049.9 Unspecified non-arthropod-borne viral diseases of central nervous system (approximate)