G37.2
BillableCentral pontine myelinolysis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G37.2 an HCC code?
Yes. G37.2 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 G37.2
For G37.2 to 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 G37.2 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G37.2 is the ICD-10-CM diagnosis code for central pontine myelinolysis. A rare condition where the pons (a critical part of the brainstem) is damaged due to osmotic imbalance, typically from rapid sodium correction, causing paralysis and neurological symptoms. G37.2 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, G37.2 maps to Multiple Sclerosis (HCC 198) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, G37.2 mapped to the same category but with a base RAF weight of 0.476 — 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.
Document the precipitating cause, usually rapid correction of hyponatremia or hypernatremia. Because G37.2 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 G37.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the precipitating cause, usually rapid correction of hyponatremia or hypernatremia
- •Review laboratory values and fluid management history to support diagnosis
Clinical Significance
Central pontine myelinolysis (osmotic demyelination syndrome) is a serious neurological condition where the myelin sheath in the pons is destroyed, usually due to rapid correction of hyponatremia. It can cause devastating consequences including locked-in syndrome. Accurate coding captures both the severity of the condition and the iatrogenic nature, which has important quality-of-care implications.
Documentation Requirements
- ✓Documentation specifying central pontine myelinolysis or osmotic demyelination syndrome
- ✓MRI findings showing characteristic pontine demyelination lesion
- ✓Documentation of the precipitating cause (rapid sodium correction, hyponatremia management)
- ✓Serial sodium laboratory values demonstrating the rate of correction
- ✓Neurological examination documenting quadriparesis, dysarthria, dysphagia, or other brainstem findings
- ✓Treatment plan and rehabilitation goals
Commonly Confused Codes
- •G37.1 — Central demyelination of corpus callosum (Marchiafava-Bignami disease); affects corpus callosum, not pons
- •G37.0 — Diffuse sclerosis of CNS; widespread demyelination rather than focal pontine
- •I63.x — Cerebral infarction; vascular etiology vs. osmotic demyelination
- •G37.9 — Demyelinating disease of CNS, unspecified; too nonspecific when pontine myelinolysis is confirmed
- •G35 — Multiple sclerosis; chronic autoimmune demyelination, not osmotic