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ICD-10 Guide
ICD-10 CodesB34.0

B34.0

Herpesviral encephalitis

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 B34.0 is a billable code used to indicate a diagnosis of herpesviral encephalitis.

Key Diagnostic Point:

Herpesviral encephalitis is a severe neurological condition primarily caused by the herpes simplex virus (HSV), most commonly HSV type 1. It is characterized by inflammation of the brain, leading to symptoms such as fever, headache, seizures, confusion, and altered mental status. The condition can progress rapidly, resulting in significant morbidity and mortality if not treated promptly. Diagnosis typically involves a combination of clinical evaluation, imaging studies such as MRI, and laboratory tests including PCR (polymerase chain reaction) assays to detect HSV DNA in cerebrospinal fluid (CSF). Early initiation of antiviral therapy, particularly with acyclovir, is crucial for improving outcomes. The condition may also be associated with other complications, including neurological deficits and seizures, necessitating comprehensive management and follow-up care.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between types of herpes viruses (HSV-1 vs. HSV-2)
  • Need for precise documentation of clinical symptoms and diagnostic tests
  • Potential for overlapping symptoms with other encephalitides
  • Variability in presentation and severity among patients

Audit Risk Factors

  • Inadequate documentation of clinical symptoms
  • Failure to include laboratory test results
  • Misidentification of the causative virus
  • Lack of clarity in the treatment plan

Specialty Focus

Medical Specialties

Neurology

Documentation Requirements

Detailed neurological examination findings, imaging results, and laboratory test outcomes.

Common Clinical Scenarios

Patients presenting with acute onset of seizures, altered mental status, or focal neurological deficits.

Billing Considerations

Ensure comprehensive documentation of neurological assessments and any changes in mental status.

Infectious Disease

Documentation Requirements

Clear documentation of viral testing, treatment regimens, and response to therapy.

Common Clinical Scenarios

Patients with confirmed HSV infection presenting with neurological symptoms.

Billing Considerations

Document the rationale for antiviral therapy and any complications arising from the infection.

Coding Guidelines

Inclusion Criteria

Use B34.0 When
  • According to ICD
  • 10 coding guidelines, B34
  • 0 should be used when herpesviral encephalitis is confirmed or strongly suspected
  • It is essential to document the specific type of herpes virus when known
  • infectious causes

Exclusion Criteria

Do NOT use B34.0 When
  • Exclusion criteria include cases where the encephalitis is due to other infectious agents or non

Related CPT Codes

87491CPT Code

Herpes simplex virus (HSV) DNA, PCR

Clinical Scenario

Used to confirm diagnosis of herpesviral encephalitis.

Documentation Requirements

Document the reason for testing and results.

Specialty Considerations

Neurology and Infectious Disease specialists should ensure accurate linkage to the diagnosis.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of herpesviral encephalitis, improving data accuracy and facilitating better tracking of disease prevalence and treatment outcomes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of herpesviral encephalitis, improving data accuracy and facilitating better tracking of disease prevalence and treatment outcomes.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of herpesviral encephalitis, improving data accuracy and facilitating better tracking of disease prevalence and treatment outcomes.

Resources

Clinical References

  • •
    CDC - Herpes Simplex Virus

Coding & Billing References

  • •
    CDC - Herpes Simplex Virus

Frequently Asked Questions

What is the primary cause of herpesviral encephalitis?

The primary cause of herpesviral encephalitis is the herpes simplex virus, most commonly HSV-1.

How is herpesviral encephalitis diagnosed?

Diagnosis is made through clinical evaluation, MRI imaging, and PCR testing of cerebrospinal fluid to detect HSV DNA.

What is the recommended treatment for herpesviral encephalitis?

The recommended treatment is intravenous acyclovir, which should be initiated as soon as the diagnosis is suspected.