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ICD-10 Guide
DiagnosesAutoimmune Encephalopathy

Autoimmune Encephalopathy

ICD-10 Coding for Autoimmune Encephalopathy(G04.81, G93.40)

PRIMARY SPECIALTYNeurology
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Autoimmune Encephalopathy?
Essential facts and insights about Autoimmune Encephalopathy

Key Clinical Considerations:

  • Cognitive dysfunction, seizures, mood changes, and behavioral disturbances
  • Positive autoantibody tests (e.g., anti-NMDA receptor antibodies), MRI findings showing encephalitis
  • Neurological examination may reveal altered mental status, focal neurological deficits, or abnormal reflexes

Clinical Information

Clinical Criteria & Documentation Requirements

  • Patient history including onset and progression of symptoms, results of neurological exams, and laboratory findings
  • Use of specific terms such as 'autoimmune encephalopathy', 'encephalitis', and relevant autoantibody names
  • Examples include detailed descriptions of cognitive assessments, imaging results, and response to treatments

Coding Guidelines

Usage Guidelines & Examples

  • Follow guidelines for coding autoimmune conditions, avoid misclassifying as infectious encephalitis
  • Common errors include using incorrect codes for related but distinct conditions

Code Exclusions

Important Exclusions

  • Infectious encephalitis, metabolic encephalopathy, and other neurological disorders
  • Alternative codes for specific autoimmune diseases affecting the nervous system

Related ICD-10 Codes

Primary Codes
G04.81
Autoimmune encephalopathy
Ancillary Codes
R56.9
Differential Codes
G93.40
G04.81

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Neurology

Specialty Applications

  • Adults and children with suspected autoimmune neurological disorders
  • Neurology clinics, hospitals, and outpatient settings

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

Documentation requirements?

Comprehensive patient history, clinical findings, and laboratory results must be documented.

Billing considerations?

Ensure accurate coding to reflect the complexity of the condition and any associated treatments.