2027 ICD-10-CM Diagnosis Code G05.4Myelitis in diseases classified elsewhere
ICD-10-CM Codes›G00–G99›G00-G09›G05
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 182
- Not Chronic
G05.4 is a billable ICD-10-CM diagnosis code for myelitis in diseases classified elsewhere. 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. 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. The code is a manifestation code that cannot be reported as the principal diagnosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encephalitis.
For Medicare Advantage risk adjustment, G05.4 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
Code EditsBilling
Medicare Code Editor checks that affect claim validity for G05.4.
Medicare Risk Adjustment (HCC)Billing
G05.4 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.
- Central nervous system disorder due to Sjögren's syndrome
- Coccidioides infection of the central nervous system
- Coenurosis
- Cysticercosis myelitis
- Dengue
- Disorder of spinal cord co-occurrent with human immunodeficiency virus infection
- Epstein Barr virus infection of the central nervous system
- Histoplasma infection of central nervous system
- Infection by Coenurosis cerebralis
- Infection by Multiceps multiceps
- Infection caused by Roseolovirus
- Infection of central nervous system caused by Borreliella burgdorferi
- Infection of central nervous system caused by Cytomegalovirus
- Infection of spinal cord caused by Histoplasma
- Lyme neuroborreliosis
- Myelitis caused by Actinomyces
- Myelitis caused by Aspergillus
- Myelitis caused by bacterium
- Myelitis caused by Borreliella burgdorferi
- Myelitis caused by Coccidioides
- Myelitis caused by Coenurus cerebralis
- Myelitis caused by Cytomegalovirus
- Myelitis caused by Dengue virus
- Myelitis caused by Enterovirus
- Myelitis caused by Epstein-Barr virus
- Myelitis caused by fungus
- Myelitis caused by herpes virus
- Myelitis caused by human poliovirus
- Myelitis caused by Influenza A virus
- Myelitis caused by Influenza virus
- Myelitis caused by Plasmodium
- Myelitis caused by Roseolovirus
- Myelitis caused by Schistosoma
- Myelitis caused by Schistosoma haematobium
- Myelitis caused by Schistosoma japonicum
- Myelitis caused by Schistosoma mansoni
- Myelitis caused by Toxoplasma gondii
- Myelitis caused by Treponema pallidum
- Myelitis co-occurrent with human immunodeficiency virus infection
- Myelitis due to anti-phospholipid syndrome
- Myelitis due to Behcet disease
- Myelitis due to multiple sclerosis
- Myelitis due to sarcoidosis
- Myelitis due to Sjogren syndrome
- Myelitis due to systemic lupus erythematosus
- Myelitis due to vasculitis
- Myelitis with AIDS
- Myelopathy with AIDS
- Parasitic infection causing myelitis
- Protozoal myelitis
- Schistosoma haematobium infection
- Schistosoma japonicum infection
- Schistosoma mansoni infection
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G05.4: its own notes plus those printed at G05 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Meningomyelitis in diseases classified elsewhere
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- adenoviral encephalitis, myelitis and encephalomyelitis (A85.1)
- encephalitis, myelitis and encephalomyelitis (in) measles (B05.0)
- enteroviral encephalitis, myelitis and encephalomyelitis (A85.0)
- herpesviral [herpes simplex] encephalitis, myelitis and encephalomyelitis (B00.4)
- listerial encephalitis, myelitis and encephalomyelitis (A32.12)
- meningococcal encephalitis, myelitis and encephalomyelitis (A39.81)
- mumps encephalitis, myelitis and encephalomyelitis (B26.2)
- postchickenpox encephalitis, myelitis and encephalomyelitis (B01.1-)
- rubella encephalitis, myelitis and encephalomyelitis (B06.01)
- toxoplasmosis encephalitis, myelitis and encephalomyelitis (B58.2)
- zoster encephalitis, myelitis and encephalomyelitis (B02.0)
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 First
The underlying condition named in the note is sequenced before this code.
- underlying disease, such as:
- congenital toxoplasmosis encephalitis, myelitis and encephalomyelitis (P37.1)
- cytomegaloviral encephalitis, myelitis and encephalomyelitis (B25.8)
- encephalitis, myelitis and encephalomyelitis (in) systemic lupus erythematosus (M32.19)
- eosinophilic meningoencephalitis (B83.2)
- human immunodeficiency virus [HIV] disease (B20)
- poliovirus (A80.-)
- suppurative otitis media (H66.01-H66.4)
- systemic lupus erythematosus (M32.19)
- trichinellosis (B75)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G05.4, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming G05.4: they are not reported together with it, unless the two conditions are unrelated.
- G01 Meningitis in bacterial diseases classified elsewheremeningoencephalitis and meningomyelitis in bacterial diseases classified elsewhere (G05) names G05, which includes this code
- G02 Meningitis in other infectious and parasitic diseases classified elsewheremeningoencephalitis and meningomyelitis in other infectious and parasitic diseases classified elsewhere (G05) names G05, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Meningomyelitis See Also: Meningoencephalitis;
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 G05.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G05.4Overview
What is the ICD-10 code for myelitis in diseases classified elsewhere?
The ICD-10-CM code for myelitis in diseases classified elsewhere is G05.4 (sometimes written as G054). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G05.4 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report myelitis in diseases classified elsewhere on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G05.4 group to?
On inpatient claims, myelitis in diseases classified elsewhere maps to MS-DRG 24, 98, 99, 23, 97, with relative weights from 1.5249 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G05.4 a CC or MCC?
CMS lists G05.4 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 G05.4 be a principal diagnosis?
No. This is a manifestation code: myelitis in diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
What HCC is G05.4?
G05.4 (myelitis in diseases classified elsewhere) 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 G05.4 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G05.4 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.
