G04.81: Other encephalitis and encephalomyelitis

G04.81, other encephalitis and encephalomyelitis, is listed as a covered diagnosis in 11 Medicare billing and coding articles that apply to 36 HCPCS Level II codes, including J1569 (Injection, immune globulin, (gammagard liquid/gammagard…), J1561 (Injection, immune globulin, (gamunex-c/gammaked)…), J1459 (Injection, immune globulin (privigen), intravenous…). The articles come from 7 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.

HCPCS Level II codes with G04.81 as a covered diagnosis

CodeDescriptionMedicare coverageDMEPOS fee 2026 (state range)Articles listing it
J1569Injection, immune globulin, (gammagard liquid/gammagard liquid erc), 500 mgSpecial coverage instructions apply—4
J1561Injection, immune globulin, (gamunex-c/gammaked), non-lyophilized (e.g., liquid), 500 mgSpecial coverage instructions apply—4
J1459Injection, immune globulin (privigen), intravenous, non-lyophilized (e.g., liquid), 500 mgCarrier judgment—4
J1557Injection, immune globulin, (gammaplex), intravenous, non-lyophilized (e.g., liquid), 500 mgCarrier judgment—4
J1556Injection, immune globulin (bivigam), 500 mgCarrier judgment—4
J1568Injection, immune globulin, (octagam), intravenous, non-lyophilized (e.g., liquid), 500 mgCarrier judgment—4
J1566Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mgSpecial coverage instructions apply—4
J1554Injection, immune globulin (asceniv), 500 mgCarrier judgment—4
J1552Injection, immune globulin (alyglo), 500 mgCarrier judgment—4
J1576Injection, immune globulin (panzyga), intravenous, non-lyophilized (e.g., liquid), 500 mgSpecial coverage instructions apply—3
J1575Injection, immune globulin/hyaluronidase, (hyqvia), 100 mg immuneglobulinCarrier judgment—3
J1572Injection, immune globulin, (flebogamma/flebogamma dif), intravenous, non-lyophilized (e.g., liquid), 500 mgSpecial coverage instructions apply—3
J1577Injection, immune globulin (qivigy), 100 mgCarrier judgment—3
J9312Injection, rituximab, 10 mgSpecial coverage instructions apply—3
Q5119Injection, rituximab-pvvr, biosimilar, (ruxience), 10 mgCarrier judgment—3
Q5115Injection, rituximab-abbs, biosimilar, (truxima), 10 mgSpecial coverage instructions apply—3
J1559Injection, immune globulin (hizentra), 100 mgCarrier judgment—2
J1555Injection, immune globulin (cuvitru), 100 mgCarrier judgment—2
J1558Injection, immune globulin (xembify), 100 mgCarrier judgment—2
J1551Injection, immune globulin (cutaquig), 100 mgCarrier judgment—2
J1553Injection, immune globulin (yimmugo), 100 mgCarrier judgment—2
U00022019-ncov coronavirus, sars-cov-2/2019-ncov (covid-19), any technique, multiple types or subtypes (includes all targets), non-cdcCarrier judgment—4
U0001Cdc 2019 novel coronavirus (2019-ncov) real-time rt-pcr diagnostic panelCarrier judgment—4
J1599Injection, immune globulin, intravenous, non-lyophilized (e.g., liquid), not otherwise specified, 500 mgCarrier judgment—2
Q5123Injection, rituximab-arrx, biosimilar, (riabni), 10 mgCarrier judgment—2

11 more codes are listed. See every code with payment by region in Caduvo.

Medicare policy articles listing G04.81

A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.

Other G04 diagnoses (Encephalitis, myelitis and encephalomyelitis)

Frequently asked questions

Does Medicare cover G04.81 (Other encephalitis and encephalomyelitis)?

Medicare covers items and services, not diagnoses. 11 Medicare billing and coding articles list G04.81 as a covered diagnosis for 36 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.

Which HCPCS codes can be billed with ICD-10 G04.81?

The Level II codes from the policies most specific to this diagnosis are J1569 (Injection, immune globulin, (gammagard liquid/gammagard…, 4 articles); J1561 (Injection, immune globulin, (gamunex-c/gammaked)…, 4 articles); J1459 (Injection, immune globulin (privigen), intravenous…, 4 articles); J1557 (Injection, immune globulin, (gammaplex), intravenous…, 4 articles); J1556 (Injection, immune globulin (bivigam), 500 mg, 4 articles). Code choice depends on the item supplied; check each code's descriptor.

Which Medicare policy articles list G04.81?

A58582 (Billing and Coding: Off-label Use of Rituximab and Rituximab Biosimilars); A56786 (Billing and Coding: Immune Globulin); A57778 (Billing and Coding: Immune Globulin), and 8 more articles.

What is ICD-10-CM code G04.81?

G04.81 is the ICD-10-CM code for other encephalitis and encephalomyelitis, in category G04 (Encephalitis, myelitis and encephalomyelitis), chapter 6: Diseases of the nervous system.

Next steps

Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.

Chapter 6: Diseases of the nervous system · All diagnoses · HCPCS lookup