G21.4: Vascular parkinsonism
G21.4, vascular parkinsonism, is listed as a covered diagnosis in 7 Medicare billing and coding articles that apply to 12 HCPCS Level II codes, including G0340 (Image-guided robotic linear accelerator-based stereotactic…), G0339 (Image-guided robotic linear accelerator-based stereotactic…), G2187 (Patients with clinical indications for imaging of the…). The articles come from 5 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with G21.4 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G0340 | Image-guided robotic linear accelerator-based stereotactic radiosurgery, delivery including collimator changes and custom plugging, fractionated treatment, all lesions, per session, second through fifth sessions, maximum five sessions per course of treatment | Carrier judgment | — | 1 |
| G0339 | Image-guided robotic linear accelerator-based stereotactic radiosurgery, complete course of therapy in one session or first session of fractionated treatment | Carrier judgment | — | 1 |
| G2187 | Patients with clinical indications for imaging of the head: head trauma | Carrier judgment | — | 1 |
| G2188 | Patients with clinical indications for imaging of the head: new or change in headache above 50 years of age | Carrier judgment | — | 1 |
| G2189 | Patients with clinical indications for imaging of the head: abnormal neurologic exam | Carrier judgment | — | 1 |
| G2190 | Patients with clinical indications for imaging of the head: headache radiating to the neck | Carrier judgment | — | 1 |
| G2191 | Patients with clinical indications for imaging of the head: positional headaches | Carrier judgment | — | 1 |
| G2192 | Patients with clinical indications for imaging of the head: temporal headaches in patients over 55 years of age | Carrier judgment | — | 1 |
| G2193 | Patients with clinical indications for imaging of the head: new onset headache in pre-school children or younger (<6 years of age) | Carrier judgment | — | 1 |
| G2194 | Patients with clinical indications for imaging of the head: new onset headache in pediatric patients with disabilities for which headache is a concern as inferred from behavior | Carrier judgment | — | 1 |
| G2195 | Patients with clinical indications for imaging of the head: occipital headache in children | Carrier judgment | — | 1 |
| G0255 | Current perception threshold/sensory nerve conduction test, (snct) per limb, any nerve | Non-covered by Medicare | Not covered | 5 |
Medicare policy articles listing G21.4
- A59350: Billing and Coding: Radiation Therapies (Palmetto GBA (MAC - Part A, MAC - Part B); 2 Level II codes). LCD with the same title: L39553
- A57307: Billing and Coding: Nerve Conduction Studies and Electromyography (CGS Administrators, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57478: Billing and Coding: Nerve Conduction Studies and Electromyography (WPS Insurance Corporation (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A54969: Billing and Coding: Nerve Conduction Studies and Electromyography (Noridian Healthcare Solutions, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57668: Billing and Coding: Nerve Conduction Studies and Electromyography (Wellpoint Federal (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56619: Billing and Coding: Nerve Conduction Studies and Electromyography (Palmetto GBA (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56612: Billing and Coding: CT of the Head (Palmetto GBA (MAC - Part A, MAC - Part B); 9 Level II codes). LCD with the same title: L34417
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other G21 diagnoses (Secondary parkinsonism)
- G21.0 — Malignant neuroleptic syndrome
- G21.11 — Neuroleptic induced parkinsonism
- G21.19 — Other drug induced secondary parkinsonism
- G21.2 — Secondary parkinsonism due to other external agents
- G21.3 — Postencephalitic parkinsonism
- G21.8 — Other secondary parkinsonism
- G21.9 — Secondary parkinsonism, unspecified
Frequently asked questions
Does Medicare cover G21.4 (Vascular parkinsonism)?
Medicare covers items and services, not diagnoses. 7 Medicare billing and coding articles list G21.4 as a covered diagnosis for 12 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 G21.4?
The Level II codes from the policies most specific to this diagnosis are G0340 (Image-guided robotic linear accelerator-based stereotactic…, 1 article); G0339 (Image-guided robotic linear accelerator-based stereotactic…, 1 article); G2187 (Patients with clinical indications for imaging of the…, 1 article); G2188 (Patients with clinical indications for imaging of the…, 1 article); G2189 (Patients with clinical indications for imaging of the…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list G21.4?
A59350 (Billing and Coding: Radiation Therapies); A57307 (Billing and Coding: Nerve Conduction Studies and Electromyography); A57478 (Billing and Coding: Nerve Conduction Studies and Electromyography), and 4 more articles.
What is ICD-10-CM code G21.4?
G21.4 is the ICD-10-CM code for vascular parkinsonism, in category G21 (Secondary parkinsonism), chapter 6: Diseases of the nervous system.
Next steps
- Run a reimbursement report for a device billed under G0340
- Watch G0340 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G0340
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 6: Diseases of the nervous system · All diagnoses · HCPCS lookup