2027 ICD-10-CM Diagnosis Code G36.9Acute disseminated demyelination, unspecified
ICD-10-CM Codes›G00–G99›G35-G37›G36
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 198
- Chronic Condition
G36.9 is a billable ICD-10-CM diagnosis code for acute disseminated demyelination, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 58 through 60, 974 through 976. 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 166 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (neither hereditary nor degenerative).
For Medicare Advantage risk adjustment, G36.9 maps to CMS-HCC Category 198 (Multiple Sclerosis) under the V28 model, adding a risk factor of about 0.647 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G36.9 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.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G36.9: its own notes plus those printed at G36 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
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.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Neuromyelitis G36.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Degenerative Nerve Diseases
Degenerative nerve diseases affect many of your body's activities, such as balance, movement, talking, breathing, and heart function. Many of these diseases are genetic. Sometimes the cause is a medical condition such as alcoholism, a tumor, or a stroke. Other causes may include toxins, chemicals, and viruses.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G36.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G36.9Overview
What is the ICD-10 code for acute disseminated demyelination, unspecified?
The ICD-10-CM code for acute disseminated demyelination, unspecified is G36.9 (sometimes written as G369). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G36.9 (Other acute disseminated demyelination) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute disseminated demyelination, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G36.9 group to?
When acute disseminated demyelination, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 974, 976, 60, 975, 58, 59, with relative weights from 0.7879 to 3.0488 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G36.9 a CC or MCC?
CMS lists G36.9 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 166 closely related codes in its exclusion list.
Can G36.9 be reported with G04.01?
Not as a rule. The Excludes1 note at G36, which applies to G36.9, lists "postinfectious encephalitis and encephalomyelitis NOS (G04.01)". 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 G36.9?
G36.9 (acute disseminated demyelination, unspecified) maps to CMS-HCC Category 198 (Multiple Sclerosis), commonly written as HCC 198, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 77 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does G36.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G36.9 adds a risk adjustment factor of about 0.647 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.226 to 1.143 depending on the payment segment). HCC 198 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 198 category page.
