G36.1
BillableAcute and subacute hemorrhagic leukoencephalitis [Hurst]
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G36.1 an HCC code?
Yes. G36.1 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 G36.1
For G36.1 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 G36.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G36.1 is the ICD-10-CM diagnosis code for acute and subacute hemorrhagic leukoencephalitis [hurst]. A severe, rapidly developing brain inflammation characterized by bleeding and destruction of the protective coating around nerve fibers, often following infection or vaccination. G36.1 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, G36.1 maps to Multiple Sclerosis (HCC 198) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, G36.1 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.
This is a medical emergency; ensure acute onset and hemorrhagic features are documented. Because G36.1 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 G36.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a medical emergency; ensure acute onset and hemorrhagic features are documented
- •Look for preceding infection or vaccination history in the clinical record to support diagnosis
Clinical Significance
Acute and subacute hemorrhagic leukoencephalitis (Hurst disease) is a rare, severe, often fatal form of acute disseminated encephalomyelitis characterized by rapid brain inflammation with hemorrhagic necrosis. It typically follows an infection or vaccination and represents a neurological emergency. Accurate coding captures the severity and acuity of this life-threatening condition.
Documentation Requirements
- ✓Documentation specifying acute hemorrhagic leukoencephalitis or Hurst disease
- ✓Neuroimaging (MRI/CT) showing hemorrhagic demyelinating lesions
- ✓Acute onset with rapid neurological deterioration documented in the timeline
- ✓Preceding infection or vaccination history within days to weeks of onset
- ✓Cerebrospinal fluid analysis results if lumbar puncture was performed
- ✓Intensive care management documentation and treatment plan
Commonly Confused Codes
- •G36.9 — Acute disseminated demyelination, unspecified; does not capture the hemorrhagic component
- •G04.00/G04.01 — Acute disseminated encephalitis; non-hemorrhagic form of the same spectrum
- •G36.0 — Neuromyelitis optica; different pathophysiology and clinical course
- •I61.x — Nontraumatic intracerebral hemorrhage; vascular etiology, not inflammatory/demyelinating
- •G36.8 — Other specified acute disseminated demyelination; use for non-hemorrhagic acute disseminated conditions