G43.C1 ICD-10-CM Code: Periodic headache syndromes in child or adult, intractable
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G43.C1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidancePeriodic headache syndromes in child or adult, intractable
Recurring headache patterns that occur at regular intervals in children or adults and do not respond adequately to standard treatment methods.
Buddy Insight
Periodic headache syndromes in child or adult encompass episodic syndromes that may be associated with migraine, including benign paroxysmal vertigo, benign paroxysmal torticollis, and other periodic phenomena.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
MappedHCC 166
RAF 0.0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Periodic headache syndromes in child or adult, with refractory migraine
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G43.C1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G43.C1 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G43.C1 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G43.C1 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G43.C1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G43.C1 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is G43.C1 an HCC code?
No. G43.C1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
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.
Work G43.C1 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for G43.C1
For G43.C1to 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 G43.C1 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
G43.C1 is the ICD-10-CM diagnosis code for periodic headache syndromes in child or adult, intractable. Recurring headache patterns that occur at regular intervals in children or adults and do not respond adequately to standard treatment methods. G43.C1 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
G43.C1 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This code does not map to a CMS-HCC V28 payment category. Capture depends on documentation that supports the diagnosis; verify the HCC assignment against the current CMS mapping for the applicable payment year. Coders reviewing G43.C1 should check whether additional documentation would support a more specific child code in the same hierarchy that does map to a payment HCC, capturing the correct specificity is the highest-impact RAF improvement available within accurate coding.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G43.C1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific periodic pattern and frequency of headaches in the medical record
- •Confirm intractability status; this code requires documentation that treatment has been attempted and failed
Clinical Significance
Periodic headache syndromes in child or adult encompass episodic syndromes that may be associated with migraine, including benign paroxysmal vertigo, benign paroxysmal torticollis, and other periodic phenomena. These conditions are considered migraine precursors or equivalents, particularly in pediatric populations, and may evolve into typical migraine over time. Accurate coding supports monitoring for migraine development and appropriate preventive treatment when indicated.
Documentation Requirements
- ✓Specific periodic syndrome type documented (paroxysmal vertigo, torticollis, etc.)
- ✓Episodic pattern with symptom-free intervals documented
- ✓Age of onset and any evolution of symptoms over time
- ✓Family history of migraine (strengthens diagnostic association)
- ✓Exclusion of other causes (epilepsy, vestibular disorders, structural pathology)
- ✓Intractability status: failed standard treatment approaches
- ✓Neurological examination findings during and between episodes
Commonly Confused Codes
- •R42 (Dizziness and giddiness): non-specific symptom code; use specific periodic syndrome code when diagnosed
- •G43.909 (Migraine, unspecified): use when typical migraine is present, not periodic syndrome
- •H81.1 (Benign paroxysmal positional vertigo): BPPV is a vestibular disorder, not a migraine variant
- •G40.x (Epilepsy): paroxysmal episodes may mimic seizures; EEG helps differentiate
- •R51.9 (Headache, unspecified): does not capture the specific periodic syndrome diagnosis