G20.C: Parkinsonism, unspecified
G20.C, parkinsonism, unspecified, is listed as a covered diagnosis in 6 Medicare billing and coding articles that apply to 17 HCPCS Level II codes, including G0340 (Image-guided robotic linear accelerator-based stereotactic…), G0339 (Image-guided robotic linear accelerator-based stereotactic…), G0563 (Stereotactic body radiation therapy, treatment delivery…). The articles come from 3 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 G20.C 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 |
| G0563 | Stereotactic body radiation therapy, treatment delivery, per fraction to 1 or more lesions, including image guidance and real-time positron emissions-based delivery adjustments to 1 or more lesions, entire course not to exceed 5 fractions | Carrier judgment | — | 1 |
| G0451 | Development testing, with interpretation and report, per standardized instrument form | 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 |
| G0283 | Electrical stimulation (unattended), to one or more areas for indication(s) other than wound care, as part of a therapy plan of care | Carrier judgment | — | 1 |
| G0281 | Electrical stimulation, (unattended), to one or more areas, for chronic stage iii and stage iv pressure ulcers, arterial ulcers, diabetic ulcers, and venous stasis ulcers not demonstrating measurable signs of healing after 30 days of conventional care, as part of a therapy plan of care | Carrier judgment | — | 1 |
| G0329 | Electromagnetic therapy, to one or more areas for chronic stage iii and stage iv pressure ulcers, arterial ulcers, diabetic ulcers and venous stasis ulcers not demonstrating measurable signs of healing after 30 days of conventional care as part of a therapy plan of care | Carrier judgment | — | 1 |
| G0255 | Current perception threshold/sensory nerve conduction test, (snct) per limb, any nerve | Non-covered by Medicare | Not covered | 2 |
Medicare policy articles listing G20.C
- A56874: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) (Wellpoint Federal (MAC - Part A, MAC - Part B); 3 Level II codes). LCD with the same title: L35076
- 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
- A56937: Billing and Coding: Psychiatry and Psychology Services (Wellpoint Federal (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L33632, L34616
- 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
- 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
- A53064: Billing and Coding: Outpatient Occupational Therapy (Palmetto GBA (MAC - Part A); 3 Level II codes). LCD with the same title: L34427
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 G20 diagnoses (Parkinson's disease)
- G20.A1 — Parkinson's disease without dyskinesia, without mention of…
- G20.A2 — Parkinson's disease without dyskinesia, with fluctuations
- G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations
- G20.B2 — Parkinson's disease with dyskinesia, with fluctuations
Frequently asked questions
Does Medicare cover G20.C (Parkinsonism, unspecified)?
Medicare covers items and services, not diagnoses. 6 Medicare billing and coding articles list G20.C as a covered diagnosis for 17 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 G20.C?
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); G0563 (Stereotactic body radiation therapy, treatment delivery…, 1 article); G0451 (Development testing, with interpretation and report, per…, 1 article); G2187 (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 G20.C?
A56874 (Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT)); A57478 (Billing and Coding: Nerve Conduction Studies and Electromyography); A56937 (Billing and Coding: Psychiatry and Psychology Services), and 3 more articles.
What is ICD-10-CM code G20.C?
G20.C is the ICD-10-CM code for parkinsonism, unspecified, in category G20 (Parkinson's disease), 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