2024 ICD-10-CM Diagnosis Code G04.81

Other encephalitis and encephalomyelitis

ICD-10-CM Code:
ICD-10 Code for:
Other encephalitis and encephalomyelitis
Is Billable?
Yes - Valid for Submission
Chronic Condition Indicator: [1]
Not chronic
Code Navigator:

Code Classification

  • Diseases of the nervous system
    • Inflammatory diseases of the central nervous system
      • Encephalitis, myelitis and encephalomyelitis

G04.81 is a billable diagnosis code used to specify a medical diagnosis of other encephalitis and encephalomyelitis. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2023 through September 30, 2024.

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

  • Allergic encephalitis
  • Allergic encephalitis
  • Allergic encephalitis
  • Allergic encephalomyelitis
  • Autoimmune acquired autonomic encephalomyelitis
  • Autoimmune cerebellar inflammation
  • Autoimmune encephalitis
  • Autoimmune encephalitis caused by N-methyl D-aspartate receptor antibody
  • Autoimmune encephalitis caused by N-methyl-D-aspartate receptor antibody
  • Autoimmune myelopathy
  • Autonomic disorder due to autoimmune encephalitis
  • Autonomic disorder due to encephalitis
  • Bickerstaff's brainstem encephalitis
  • Brainstem encephalitis
  • Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids
  • Dementia due to autoimmune encephalitis
  • Dementia due to autoimmune encephalitis
  • Dementia due to Hashimoto encephalopathy
  • Encephalitis caused by human immunodeficiency virus type 2
  • Epilepsy due to Rasmussen syndrome
  • Epileptic encephalopathy
  • Epileptic encephalopathy
  • Experimental allergic encephalomyelitis
  • Focal encephalitis
  • Focal encephalitis
  • Granulomatous meningoencephalomyelitis
  • Human immunodeficiency virus encephalitis
  • Human immunodeficiency virus II infection
  • Infectious mononucleosis encephalitis
  • Limbic encephalitis
  • Limbic encephalitis
  • Limbic encephalitis with contactin-associated protein-like 2 antibodies
  • Limbic encephalitis with dipeptidyl-peptidase 6 antibodies
  • Limbic encephalitis with leucine-rich glioma-inactivated 1 antibodies
  • Limbic encephalitis with neurexin-3 antibodies
  • Limbic encephalitis with N-methyl-D-aspartate receptor antibodies
  • Meningoencephalomyelitis
  • Meningoencephalomyelitis
  • Meningomyelitis
  • Meningomyelitis
  • Non-herpetic acute limbic encephalitis
  • Post-transplant acute limbic encephalitis
  • Pyogranulomatous meningoencephalomyelitis
  • Rasmussen syndrome
  • Rasmussen syndrome
  • Rasmussen syndrome, refractory
  • Retroviridae encephalitis

Clinical Classification

Clinical Information

  • Limbic Encephalitis

    a paraneoplastic syndrome marked by degeneration of neurons in the limbic system. clinical features include hallucinations, loss of episodic memory; anosmia; ageusia; temporal lobe epilepsy; dementia; and affective disturbance (depression). circulating anti-neuronal antibodies (e.g., anti-hu; anti-yo; anti-ri; and anti-ma2) and small cell lung carcinomas or testicular carcinoma are frequently associated with this syndrome.
  • Limbic Encephalitis

    a rare disorder characterized by degenerative changes in the limbic area of the brain. causes include infections and autoimmune conditions; it may also manifest as a paraneoplastic syndrome, most often caused by small cell lung carcinoma. signs and symptoms include behavioral changes, hallucinations and dementia.
  • Autoimmune Encephalitis

    inflammation of the brain secondary to an immune response triggered by the body itself.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.

Inclusion Terms

Inclusion 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.
  • Noninfectious acute disseminated encephalomyelitis (noninfectious ADEM)

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Convert G04.81 to ICD-9-CM

  • ICD-9-CM Code: 323.81 - Enceph & encephlalo NEC
    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.

Patient Education


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
  • Drowsiness
  • Vomiting
  • Confusion
  • Seizures

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]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • 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. This was the first year ICD-10-CM was implemented into the HIPAA code set.


[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.