Tick-borne viral encephalitis
In Viral and prion infections of the central nervous system (A80-A89), chapter 1: Certain Infectious and Parasitic Diseases
5 billable codes under A84: all are an MCC; none map to an HCC.A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment.
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Instructional notes
Includes: conditions that are coded here
- tick-borne viral meningoencephalitis
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 A84.
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)
All codes under A84
A84 can't be used on a claim. Pick a billable code below; grey headings group them.
A84 MS-DRGs
As the principal diagnosis, all 5 billable codes under A84 group to MS-DRG 023, 024, 097, 098, or 099 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 023 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator
- DRG 024 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC
- 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
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
Encephalitis
Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.
Read more about encephalitis 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.