ICD-10 A85.8
Billable / Specific CCOther specified viral encephalitis
About ICD-10-CM A85.8
ICD-10-CM code A85.8 represents Other specified viral encephalitis. This is a billable/specific code in the Infectious and Parasitic Diseases chapter (block A85). The 2026 edition of ICD-10-CM A85.8 became effective on October 1, 2025.
Coding Tips for A85.8
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
A85.8 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under A85.8. Per CMS ICD-10-CM Tabular 2026.
- Encephalitis lethargica
- Von Economo-Cruchet disease
Inpatient DRG Impact, CC
codes Other specified viral encephalitis. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for A85.8
Local Coverage Determinations (LCDs) from CMS MACs that list A85.8 as a covered diagnosis.
Showing top 10 of 606 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing A85.8.
2 Cigna
5 Medicare
CPT Codes Commonly Billed with A85.8
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- J2791 CMS LCD: Billing and Coding: Intravenous Immunoglobulin (IVIG) CMS LCD
- J2792 CMS LCD: Billing and Coding: Intravenous Immunoglobulin (IVIG) CMS LCD
- G2189 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2194 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2193 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2187 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2188 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2191 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2190 CMS LCD: Billing and Coding: CT of the Head CMS LCD
- G2192 CMS LCD: Billing and Coding: CT of the Head CMS LCD
Convert A85.8 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 |
|---|---|---|
| A85.8 | 0498 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To A85.8
Other codes in section A80-A89 (Viral and prion infections of the central nervous system).
ICD-10 A85.8, Billing FAQ
Is ICD-10 code A85.8 billable? +
Yes, A85.8 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to A85.8? +
ICD-10 A85.8 includes: Encephalitis lethargica; Von Economo-Cruchet disease.
Is A85.8 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with A85.8? +
Procedures frequently paired with A85.8 include: J2791, J2792, G2189, G2194, G2193.
What ICD-9 codes does A85.8 map to? +
Per CMS GEMs, A85.8 maps to ICD-9 codes: 0498. 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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