2027 ICD-10-CM Diagnosis Code G04.1Tropical spastic paraplegia
ICD-10-CM Codes›G00–G99›G00-G09›G04
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 182
- Chronic Condition
G04.1 is a billable ICD-10-CM diagnosis code for tropical spastic paraplegia. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 52 through 53. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 138 closely related codes. Coders also document this condition as disease caused by Deltaretrovirus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Paralysis (other than cerebral palsy).
For Medicare Advantage risk adjustment, G04.1 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
G04.1 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.
- Disease caused by Deltaretrovirus
- Human T-cell lymphotropic virus 1-associated myelopathy
- Human T-lymphotropic virus 1 infection
- Infection caused by Human T-lymphotropic virus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G04.1: its own notes plus those printed at 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)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G04.1, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming G04.1: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 1
These codes carry an Excludes2 note naming G04.1: 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.
tropical G04.1
tropical spastic G04.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Paraparesis, Tropical Spastic
a subacute paralytic myeloneuropathy occurring endemically in tropical areas such as the caribbean, colombia, india, and africa, as well as in the southwestern region of japan; associated with infection by human t-cell leukemia virus i. clinical manifestations include a slowly progressive spastic weakness of the legs, increased reflexes, babinski signs, incontinence, and loss of vibratory and position sensation. on pathologic examination inflammatory, demyelination, and necrotic lesions may be found in the spinal cord. (adams et al., principles of neurology, 6th ed, p1239)
Patient EducationClinical
Encephalitis
Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.
The full article covers:
- What is encephalitis?
- What causes encephalitis?
- Who is more likely to get encephalitis?
- What are the symptoms of encephalitis?
- How is encephalitis diagnosed?
- What are the treatments for encephalitis?
- Can encephalitis be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G04.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G04.1Overview
What is the ICD-10 code for tropical spastic paraplegia?
The ICD-10-CM code for tropical spastic paraplegia is G04.1 (sometimes written as G041). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G04.1 (Encephalitis, myelitis and encephalomyelitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report tropical spastic paraplegia on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G04.1 group to?
When tropical spastic paraplegia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 53, 52, with relative weights from 0.9723 to 1.7843 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G04.1 a CC or MCC?
CMS lists G04.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 138 closely related codes in its exclusion list.
Can G04.1 be reported with G93.40?
Not as a rule. The Excludes1 note at G04, which applies to G04.1, 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 G04.1?
G04.1 (tropical spastic paraplegia) 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 G04.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G04.1 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.
