G37.89
BillableOther specified demyelinating diseases of central nervous system
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G37.89 an HCC code?
Yes. G37.89 maps to Multiple Sclerosis under the CMS-HCC V28 risk adjustment model (and Multiple Sclerosis under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for G37.89
For G37.89to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G37.89 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G37.89 is the ICD-10-CM diagnosis code for other specified demyelinating diseases of central nervous system. Other specified conditions involving damage to nerve insulation in the brain and spinal cord that do not fit into standard demyelinating disease categories. G37.89 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering demyelinating diseases of the central nervous system (g35-g37).
Under the CMS-HCC V28 risk adjustment model, G37.89 maps to Multiple Sclerosis (HCC 198) with a community, non-dual, aged base RAF weight of 0.647. Under the older V24 model, G37.89 mapped to the same category but with a base RAF weight of 0.423 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only when a specific demyelinating disease is documented but does not fit other G37 categories. Because G37.89 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G37.89 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when a specific demyelinating disease is documented but does not fit other G37 categories
- •Always document the specific type of demyelinating disease in the medical record to support this code selection
Clinical Significance
Other specified demyelinating diseases of the central nervous system captures demyelinating conditions that have been identified by the provider but do not fit other specific G37 categories. These are typically rare conditions requiring specialized neurological management. Accurate coding ensures these uncommon but serious conditions are properly represented for risk adjustment.
Documentation Requirements
- ✓Documentation specifying the exact demyelinating disease
- ✓Neuroimaging showing demyelinating lesions
- ✓Evidence that more specific codes (G37.0-G37.81) have been considered and excluded
- ✓Neurological examination findings consistent with demyelinating disease
- ✓Treatment plan for the specific condition
- ✓Distinction from non-demyelinating neurological conditions
Commonly Confused Codes
- •G37.9 — Demyelinating disease of CNS, unspecified; use when the specific type is not determined
- •G37.81 — MOGAD; has its own specific code and should not use G37.89
- •G35 — Multiple sclerosis; the most common demyelinating disease with its own code
- •G37.5 — Concentric sclerosis (Balo); has its own specific code
- •G36.8 — Other specified acute disseminated demyelination; for acute presentations specifically