2027 ICD-10-CM Diagnosis Code G04.89Other myelitis
ICD-10-CM Codes›G00–G99›G00-G09›G04
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 182
- Not Chronic
G04.89 is a billable ICD-10-CM diagnosis code for other myelitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 23 through 24, 97 through 99, 974 through 976. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 182 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encephalitis.
For Medicare Advantage risk adjustment, G04.89 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G04.89 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Coxsackievirus infection of the central nervous system
- Disease caused by Deltaretrovirus
- Disorder of spinal cord due to and following radiotherapy
- Enteroviral neurological disease
- Human T-lymphotropic virus 1 infection
- Infection caused by Human T-lymphotropic virus
- Infection caused by Mycoplasmoides pneumoniae
- Myelitis caused by bacterium
- Myelitis caused by Enterovirus
- Myelitis caused by Human coxsackievirus A
- Myelitis caused by Human coxsackievirus B
- Myelitis caused by Human echovirus
- Myelitis caused by human T-lymphotropic virus type 1
- Myelitis caused by Mycoplasmoides pneumoniae
- Myelitis caused by passive antibody therapy
- Myelitis caused by Retroviridae
- Post-infective myelitis
- Radiation myelitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G04.89: its own notes plus those printed at G04.8, G04, and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- acute ascending myelitis
- meningoencephalitis
- meningomyelitis
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- 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)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G04.89, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming G04.89: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 1
These codes carry an Excludes2 note naming G04.89: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Infection, infected, infective (opportunistic) B99.9
spinal cord NOS See Also: Myelitis; G04.91
streptococcal G04.89
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Spinal Cord Diseases
Your spinal cord is a bundle of nerves that runs down the middle of your back. It carries signals back and forth between your body and your brain. It is protected by your vertebrae, which are the bone disks that make up your spine.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G04.89 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G04.89Overview
What is the ICD-10 code for other myelitis?
The ICD-10-CM code for other myelitis is G04.89 (sometimes written as G0489). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G04.89 (Other encephalitis, myelitis and encephalomyelitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other myelitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G04.89 group to?
When other myelitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 24, 98, 974, 976, 99, 975, 23, 97, with relative weights from 0.7879 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G04.89 a CC or MCC?
CMS lists G04.89 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 182 closely related codes in its exclusion list.
Can G04.89 be reported with G93.40?
Not as a rule. The Excludes1 note at G04, which applies to G04.89, lists "encephalopathy NOS (G93.40)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is G04.89?
G04.89 (other myelitis) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does G04.89 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G04.89 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
