2025 ICD-10-CM code A86
Unspecified viral encephalitis.
Medical necessity is established by the clinical presentation and confirmed diagnosis of encephalitis.The medical record should clearly document the symptoms and diagnostic findings supporting the diagnosis.
Clinicians diagnose viral encephalitis based on patient history, physical examination, neurological examination, and laboratory/imaging studies (e.g., CT, EEG, MRI, spinal tap for CSF analysis). Treatment focuses on managing symptoms (e.g., corticosteroids, rest, fluids, pain relievers) and may require hospitalization for severe cases.
- Certain infectious and parasitic diseases (A00-B99)
- Viral and prion infections of the central nervous system (A80-A89)
In simple words: This code indicates swelling of the brain due to a viral infection, when the specific virus isn't known.
Viral encephalitis refers to inflammation and/or swelling of the brain due to a virus.This code is used when the specific type of virus causing the encephalitis is not documented.
Example 1: A patient presents with fever, headache, stiff neck, and altered mental status. Diagnostic testing confirms encephalitis, but the specific viral cause is undetermined. A86 is assigned., An individual is admitted to the hospital with seizures and confusion.MRI reveals brain inflammation consistent with encephalitis, but testing fails to identify a specific virus. A86 is appropriate., A child experiences lethargy, vomiting, and a high fever.Lumbar puncture shows signs of infection, but no specific virus is isolated.The physician diagnoses unspecified viral encephalitis and uses A86.
Documentation should include signs and symptoms, results of diagnostic tests (e.g., CSF analysis, imaging), and treatment provided. If a specific virus is later identified, the code should be updated accordingly.
- Specialties:Infectious Disease, Neurology, Pediatrics
- Place of Service:Inpatient Hospital, Emergency Room - Hospital, Office