G31.9: Degenerative disease of nervous system, unspecified
G31.9, degenerative disease of nervous system, unspecified, is listed as a covered diagnosis in 5 Medicare billing and coding articles that apply to 12 HCPCS Level II codes, including A9552 (Fluorodeoxyglucose f-18 fdg, diagnostic, per study dose…), A9597 (Positron emission tomography radiopharmaceutical…), A9598 (Positron emission tomography radiopharmaceutical…). The articles come from 4 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 G31.9 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| A9552 | Fluorodeoxyglucose f-18 fdg, diagnostic, per study dose, up to 45 millicuries | Carrier judgment | — | 2 |
| A9597 | Positron emission tomography radiopharmaceutical, diagnostic, for tumor identification, not otherwise classified | Carrier judgment | — | 2 |
| A9598 | Positron emission tomography radiopharmaceutical, diagnostic, for non-tumor identification, not otherwise classified | Carrier judgment | — | 2 |
| A9601 | Flortaucipir f 18 injection, diagnostic, 1 millicurie | Carrier judgment | — | 2 |
| G0451 | Development testing, with interpretation and report, per standardized instrument form | Carrier judgment | — | 2 |
| 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 | — | 1 |
| 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 | — | 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 |
| G0219 | Pet imaging whole body; melanoma for non-covered indications | Non-covered by Medicare | Not covered | 2 |
| G0235 | Pet imaging, any site, not otherwise specified | Non-covered by Medicare | Not covered | 2 |
| G0252 | Pet imaging, full and partial-ring pet scanners only, for initial diagnosis of breast cancer and/or surgical planning for breast cancer (e.g., initial staging of axillary lymph nodes) | Non-covered by Medicare | Not covered | 2 |
| G0255 | Current perception threshold/sensory nerve conduction test, (snct) per limb, any nerve | Non-covered by Medicare | Not covered | 1 |
Medicare policy articles listing G31.9
- A53134: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions (Novitas Solutions, Inc. (MAC - Part A, MAC - Part B); 7 Level II codes)
- A59049: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions (First Coast Service Options, Inc. (MAC - Part A, MAC - Part B); 7 Level II codes)
- 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
- 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
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 G31 diagnoses (Other degenerative diseases of nervous system, not elsewhere classified)
- G31.01 — Pick's disease
- G31.09 — Other frontotemporal neurocognitive disorder
- G31.1 — Senile degeneration of brain, not elsewhere classified
- G31.80 — Leukodystrophy, unspecified
- G31.83 — Neurocognitive disorder with Lewy bodies
- G31.84 — Mild cognitive impairment of uncertain or unknown etiology
- G31.85 — Corticobasal degeneration
- G31.86 — Alexander disease
- G31.87 — Primary progressive apraxia of speech
Frequently asked questions
Does Medicare cover G31.9 (Degenerative disease of nervous system, unspecified)?
Medicare covers items and services, not diagnoses. 5 Medicare billing and coding articles list G31.9 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 G31.9?
The Level II codes from the policies most specific to this diagnosis are A9552 (Fluorodeoxyglucose f-18 fdg, diagnostic, per study dose…, 2 articles); A9597 (Positron emission tomography radiopharmaceutical…, 2 articles); A9598 (Positron emission tomography radiopharmaceutical…, 2 articles); A9601 (Flortaucipir f 18 injection, diagnostic, 1 millicurie, 2 articles); G0451 (Development testing, with interpretation and report, per…, 2 articles). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list G31.9?
A53134 (Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions); A59049 (Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions); A56937 (Billing and Coding: Psychiatry and Psychology Services), and 2 more articles.
What is ICD-10-CM code G31.9?
G31.9 is the ICD-10-CM code for degenerative disease of nervous system, unspecified, in category G31 (Other degenerative diseases of nervous system, not elsewhere classified), chapter 6: Diseases of the nervous system.
Next steps
- Run a reimbursement report for a device billed under A9552
- Watch A9552 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for A9552
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