G04

Encephalitis, myelitis and encephalomyelitis

Header / non-billable

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This code does not map to a risk-adjusting HCC in the loaded models.

Coding notes

Excludes 1 never coded together · Excludes 2 may co-exist

This code · G04

Includes

acute ascending myelitis meningoencephalitis meningomyelitis

Excludes 1

encephalopathy NOS (G93.40)

Excludes 2

acute transverse myelitis (G37.3) alcoholic encephalopathy (G31.2) multiple sclerosis (G35-) myalgic encephalomyelitis (G93.32) subacute necrotizing myelitis (G37.4) toxic encephalitis (G92.8) toxic encephalopathy (G92.8)

Inherited from chapter 6Diseases of the nervous system

Excludes 2

certain conditions originating in the perinatal period (P04-P96) certain infectious and parasitic diseases (A00-B99) complications of pregnancy, childbirth and the puerperium (O00-O9A) congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99) endocrine, nutritional and metabolic diseases (E00-E88) injury, poisoning and certain other consequences of external causes (S00-T88) neoplasms (C00-D49) symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Official Guidelines for G04

FY 2026 ›

I.C.6Chapter-specific guidanceChapter 6: Diseases of the Nervous System (G00-G99)

Subsections