A86 is a billable ICD-10 code used to specify a medical diagnosis of unspecified viral encephalitis. The code is valid during the fiscal year 2023 from October 01, 2022 through September 30, 2023 for the submission of HIPAA-covered transactions.
Unspecified diagnosis codes like A86 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.
The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:
- Acute necrotizing encephalitis
- Acute viral encephalitis
- Arenavirus encephalitis
- Arenavirus meningitis
- Chronic echovirus meningoencephalitis
- Chronic infectious disease of central nervous system
- Chronic meningitis
- Chronic viral encephalitis
- Dementia associated with viral encephalitis
- Echovirus encephalitis
- Echovirus meningitis
- Enterovirus meningitis
- Epidemic encephalitis
- Infection caused by Lymphocytic choriomeningitis virus
- Infective ventriculitis
- Lymphocytic choriomeningitis
- Lymphocytic choriomeningitis virus encephalitis
- Meningoencephalitis caused by Lymphocytic choriomeningitis virus
- Meningoencephalitis caused by virus
- Meningoencephalitis caused by virus
- Primary encephalitis
- Primary viral encephalitis
- Ventriculitis of the brain
- Viral encephalitis
- Viral ventriculitis
- Arenaviruses, Old World-. one of two groups of viruses in the arenavirus genus and considered part of the old world complex. it includes lassa virus and lymphocytic choriomeningitis virus, although the latter has worldwide distribution now.
- Lymphocytic Choriomeningitis-. a form of meningitis caused by lymphocytic choriomeningitis virus. mice and other rodents serve as the natural hosts, and infection in humans usually occurs through inhalation or ingestion of infectious particles. clinical manifestations include an influenza-like syndrome followed by stiff neck, alterations of mentation, ataxia, and incontinence. maternal infections may result in fetal malformations and injury, including neonatal hydrocephalus, aqueductal stenosis, chorioretinitis, and microcephaly. (from joynt, clinical neurology, 1996, ch26, pp1-3)
- Lymphocytic choriomeningitis virus-. the type species of arenavirus, part of the old world arenaviruses (arenaviruses, old world), producing a silent infection in house and laboratory mice. in humans, infection with lcmv can be inapparent, or can present with an influenza-like illness, a benign aseptic meningitis, or a severe meningoencephalomyelitis. the virus can also infect monkeys, dogs, field mice, guinea pigs, and hamsters, the latter an epidemiologically important host.
- Cordonnier Grade 3 Viral Complication, Viral Encephalitis|Grade 3 Any Viral Encephalitis-. any viral encephalitis.
- Mosquito-Borne Viral Encephalitis-. viral encephalitis that is transmitted by mosquitos.
- Tick-Borne Viral Encephalitis-. viral encephalitis that is transmitted by ticks.
- Viral Encephalitis-. encephalitis resulting from viral infection.
- Epidemic Encephalitis-. a term that may be used to describe encephalitis characterized by sleepiness, which is likely due to a viral cause.
Tabular List of Diseases and Injuries
The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more. The following references are applicable to this diagnosis code:
Inclusion TermsInclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
- Viral encephalomyelitis NOS
- Viral meningoencephalitis NOS
Index to Diseases and Injuries References
The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for this diagnosis code are found in the injuries and diseases index:
- - Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) - G04.90
- - Meningoencephalitis - See Also: Encephalitis; - G04.90
- - Meningoencephalomyelitis - See Also: Meningoencephalitis;
Convert to ICD-9 Code
|Source ICD-10 Code||Target ICD-9 Code|
|A86||049.9 - Viral encephalitis NOS|
|Approximate Flag - The approximate mapping means there is not an exact match between the ICD-10 and ICD-9 codes and the mapped code is not a precise representation of the original code.|
Encephalitis is an inflammation of the brain. Usually the cause is a viral infection, but bacteria can also cause it. It can be mild or severe. Most cases are mild. You may have flu-like symptoms. With a mild case, you may just need rest, plenty of fluids, and a pain reliever.
Severe cases need immediate treatment. Symptoms of severe cases include:
- Severe headache
- Sudden fever
In babies, additional symptoms may include constant crying, poor feeding, body stiffness, and bulging in the soft spots of the skull.
Severe cases may require a stay in the hospital. Treatments include oral and intravenous (IV) medicines to reduce inflammation and treat infection. Patients with breathing difficulties may need artificial respiration. Some people may need physical, speech, and occupational therapy once the illness is under control.
NIH: National Institute of Neurological Disorders and Stroke
[Learn More in MedlinePlus]
Viruses are very tiny germs. They are made of genetic material inside of a protein coating. Viruses cause familiar infectious diseases such as the common cold, flu and warts. They also cause severe illnesses such as HIV/AIDS, Ebola, and COVID-19.
Viruses are like hijackers. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves. This can kill, damage, or change the cells and make you sick. Different viruses attack certain cells in your body such as your liver, respiratory system, or blood.
When you get a virus, you may not always get sick from it. Your immune system may be able to fight it off.
For most viral infections, treatments can only help with symptoms while you wait for your immune system to fight off the virus. Antibiotics do not work for viral infections. There are antiviral medicines to treat some viral infections. Vaccines can help prevent you from getting many viral diseases.
[Learn More in MedlinePlus]
- FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
- FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
- FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
- FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
- FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
- FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
- FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
- FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016 (First year ICD-10-CM implemented into the HIPAA code set)