ICD-10 G04.01
Billable / Specific MCCPostinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
About ICD-10-CM G04.01
ICD-10-CM code G04.01 represents Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM). This is a billable/specific code in the Nervous System chapter (block G04). The 2026 edition of ICD-10-CM G04.01 became effective on October 1, 2025.
Coding Tips for G04.01
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G04.01 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Type 1 Excludes
Pure excludes, these codes can never be coded together with G04.01. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- post chickenpox encephalitis (B01.1)
- post measles encephalitis (B05.0)
- post measles myelitis (B05.1)
Inpatient DRG Impact, MCC
codes Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM). As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for G04.01
Local Coverage Determinations (LCDs) from CMS MACs that list G04.01 as a covered diagnosis.
Showing top 10 of 582 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G04.01.
5 Medicare
CPT Codes Commonly Billed with G04.01
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 95708 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95721 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95719 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95813 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95822 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95717 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95812 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95700 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
- 95705 CMS LCD: Billing and Coding: Special Electroencephalography CMS LCD
Convert G04.01 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| G04.01 | 32361 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G04.01
Other codes in section G00-G09 (Inflammatory diseases of the central nervous system).
ICD-10 G04.01, Billing FAQ
Is ICD-10 code G04.01 billable? +
Yes, G04.01 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What codes are Type 1 Excludes for G04.01? +
Type 1 Excludes (never code together with G04.01): post chickenpox encephalitis (B01.1); post measles encephalitis (B05.0); post measles myelitis (B05.1)
Is G04.01 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G04.01? +
Procedures frequently paired with G04.01 include: 95708, 95721, 95719, 95813, 95822.
What ICD-9 codes does G04.01 map to? +
Per CMS GEMs, G04.01 maps to ICD-9 codes: 32361. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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