G21.0: Malignant neuroleptic syndrome
G21.0, malignant neuroleptic syndrome, is listed as a covered diagnosis in 7 Medicare billing and coding articles that apply to 21 HCPCS Level II codes, including G0451 (Development testing, with interpretation and report, per…), G0017 (Psychotherapy for crisis furnished in an applicable site…), G0018 (Psychotherapy for crisis furnished in an applicable site…). 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 G21.0 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G0451 | Development testing, with interpretation and report, per standardized instrument form | Carrier judgment | — | 3 |
| G0017 | Psychotherapy for crisis furnished in an applicable site of service (any place of service at which the non-facility rate for psychotherapy for crisis services applies, other than the office setting); first 60 minutes | Carrier judgment | — | 2 |
| G0018 | Psychotherapy for crisis furnished in an applicable site of service (any place of service at which the non-facility rate for psychotherapy for crisis services applies, other than the office setting); each additional 30 minutes (list separately in addition to code for primary service) | Carrier judgment | — | 2 |
| G0152 | Services performed by a qualified occupational therapist in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0155 | Services of clinical social worker in home health or hospice settings, each 15 minutes | Carrier judgment | — | 1 |
| G0156 | Services of home health/hospice aide in home health or hospice settings, each 15 minutes | Carrier judgment | — | 1 |
| G0299 | Direct skilled nursing services of a registered nurse (rn) in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0300 | Direct skilled nursing services of a licensed practical nurse (lpn) in the home health or hospice setting, each 15 minutes | Carrier judgment | — | 1 |
| G0410 | Group psychotherapy other than of a multiple-family group, in a partial hospitalization or intensive outpatient setting, approximately 45 to 50 minutes | Carrier judgment | — | 1 |
| G0411 | Interactive group psychotherapy, in a partial hospitalization or intensive outpatient setting, approximately 45 to 50 minutes | Carrier judgment | — | 1 |
| G0560 | Safety planning interventions, each 20 minutes personally performed by the billing practitioner, including assisting the patient in the identification of the following personalized elements of a safety plan: recognizing warning signs of an impending suicidal or substance use-related crisis; employing internal coping strategies; utilizing social contacts and social settings as a means of distraction from suicidal thoughts or risky substance use; utilizing family members, significant others, caregivers, and/or friends to help resolve the crisis; contacting mental health or substance use disorder professionals or agencies; and making the environment safe | 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 | 1 |
Medicare policy articles listing G21.0
- A56756: Billing and Coding: Home Health - Psychiatric Care (Palmetto GBA (HHH MAC); 5 Level II codes). LCD with the same title: L34561
- A57480: Billing and Coding: Psychiatry and Psychology Services (WPS Insurance Corporation (MAC - Part A, MAC - Part B); 4 Level II codes). LCD with the same title: L33632, L34616
- 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
- A57130: Billing and Coding: Psychiatric Codes (Novitas Solutions, Inc. (MAC - Part A, MAC - Part B); 4 Level II codes). LCD with the same title: L35101
- A57780: Billing and Coding: Psychological and Neuropsychological Tests (First Coast Service Options, Inc. (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34520
- 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)
- G21.11 — Neuroleptic induced parkinsonism
- G21.19 — Other drug induced secondary parkinsonism
- G21.2 — Secondary parkinsonism due to other external agents
- G21.3 — Postencephalitic parkinsonism
- G21.4 — Vascular parkinsonism
- G21.8 — Other secondary parkinsonism
- G21.9 — Secondary parkinsonism, unspecified
Frequently asked questions
Does Medicare cover G21.0 (Malignant neuroleptic syndrome)?
Medicare covers items and services, not diagnoses. 7 Medicare billing and coding articles list G21.0 as a covered diagnosis for 21 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 G21.0?
The Level II codes from the policies most specific to this diagnosis are G0451 (Development testing, with interpretation and report, per…, 3 articles); G0017 (Psychotherapy for crisis furnished in an applicable site…, 2 articles); G0018 (Psychotherapy for crisis furnished in an applicable site…, 2 articles); G0152 (Services performed by a qualified occupational therapist…, 1 article); G0155 (Services of clinical social worker in home health or…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list G21.0?
A56756 (Billing and Coding: Home Health - Psychiatric Care); A57480 (Billing and Coding: Psychiatry and Psychology Services); A56937 (Billing and Coding: Psychiatry and Psychology Services), and 4 more articles.
What is ICD-10-CM code G21.0?
G21.0 is the ICD-10-CM code for malignant neuroleptic syndrome, in category G21 (Secondary parkinsonism), chapter 6: Diseases of the nervous system.
Next steps
- Run a reimbursement report for a device billed under G0451
- Watch G0451 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G0451
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