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ICD-10 Guide
ICD-10 CodesA79.8

A79.8

Other viral infections of central nervous system, not elsewhere classified

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

Code Description

ICD-10 A79.8 is a billable code used to indicate a diagnosis of other viral infections of central nervous system, not elsewhere classified.

Key Diagnostic Point:

A79.8 encompasses a variety of viral infections affecting the central nervous system (CNS) that do not fit into more specific categories. These infections can arise from various viral agents, including those transmitted by vectors such as mosquitoes and ticks. Rickettsial diseases, while primarily bacterial, can present with neurological symptoms that may complicate the clinical picture. Travel-related infections, such as those caused by arboviruses (e.g., West Nile virus, Zika virus), are also included under this code when they lead to CNS involvement. Clinicians must consider the patient's travel history, exposure to vectors, and symptomatology to accurately diagnose and manage these infections. The clinical manifestations can range from mild flu-like symptoms to severe neurological deficits, including encephalitis or meningitis. Diagnosis often requires a combination of clinical evaluation, serological testing, and sometimes lumbar puncture for cerebrospinal fluid analysis. Treatment is typically supportive, focusing on symptom management and addressing any complications that arise.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of viral agents involved
  • Overlap with other infectious diseases
  • Need for detailed travel history
  • Potential for co-infections

Audit Risk Factors

  • Inadequate documentation of travel history
  • Failure to specify the viral agent
  • Misclassification of symptoms
  • Lack of supporting diagnostic tests

Specialty Focus

Medical Specialties

Infectious Disease

Documentation Requirements

Detailed patient history, including travel and exposure risks, laboratory results, and clinical findings.

Common Clinical Scenarios

Patients presenting with fever, neurological symptoms, and recent travel to endemic areas.

Billing Considerations

Consideration of differential diagnoses and potential for co-infections with other vector-borne diseases.

Neurology

Documentation Requirements

Neurological examination findings, imaging results, and any lumbar puncture results.

Common Clinical Scenarios

Patients with encephalitis or meningitis symptoms with unclear etiology.

Billing Considerations

Need for comprehensive neurological assessment and potential referral to infectious disease specialists.

Coding Guidelines

Inclusion Criteria

Use A79.8 When
  • Follow official ICD
  • 10 coding guidelines, ensuring accurate documentation of the patient's clinical presentation, travel history, and any laboratory findings

Exclusion Criteria

Do NOT use A79.8 When
  • Exclude conditions that are specifically classified elsewhere

Related CPT Codes

87491CPT Code

Infectious agent detection by nucleic acid (DNA or RNA); viral, amplified probe technique

Clinical Scenario

Used when testing for specific viral agents in CNS infections.

Documentation Requirements

Document the specific viral agent being tested and the clinical rationale for testing.

Specialty Considerations

Infectious disease specialists should ensure comprehensive testing based on clinical presentation.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of viral infections, improving the ability to track and manage these conditions. A79.8 provides a catch-all for less common viral CNS infections, which can enhance epidemiological tracking.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of viral infections, improving the ability to track and manage these conditions. A79.8 provides a catch-all for less common viral CNS infections, which can enhance epidemiological tracking.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of viral infections, improving the ability to track and manage these conditions. A79.8 provides a catch-all for less common viral CNS infections, which can enhance epidemiological tracking.

Resources

Clinical References

  • •
    CDC Viral Encephalitis Information

Coding & Billing References

  • •
    CDC Viral Encephalitis Information

Frequently Asked Questions

What types of infections are included under A79.8?

A79.8 includes various viral infections of the CNS that are not classified elsewhere, such as those caused by arboviruses and other less common viral agents.