G45.8 — Other transient cerebral ischemic attacks and related syndromes
G45.8 is a billable, specific ICD-10-CM code for other transient cerebral ischemic attacks and related syndromes. It is valid for submission on a claim.
Excludes1 inherited from the categories above G45.8
These are not written on G45.8, but they bind it: a note on a category applies to every code beneath it. Billing G45.8 with anything listed here is a denial.
Other codes that can never be billed with G45.8
These codes carry an Excludes1 note pointing at G45.8. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G45.8 alone.
- I65Occlusion and stenosis of precerebral arteries, not resulting in cerebral infarction
Risk adjustment
G45.8 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
G45.8 is named in 53 Medicare coverage policies — 53 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
- A52868Billing and Coding: Transesophageal Echocardiography (TEE)
- A52992Billing and Coding: Non-Invasive Cerebrovascular Arterial Studies
- A52992Billing and Coding: Non-Invasive Cerebrovascular Arterial Studies
How G45.8 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to G45.8.
- Syndrome›subclavian steal
- Attack, attacks›transient ischemic›specified NEC
- Insufficiency, insufficient›cerebrovascular›with transient focal neurological signs and symptoms
- Ischemia, ischemic›cerebral›recurrent focal
- Syndrome›steal›subclavian
Code history
G45.8 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share G45. If G45.8 is not quite right, the correct code is usually one of these.
Questions about G45.8
- Is G45.8 a billable ICD-10-CM code?
- Yes. G45.8 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does G45.8 sit in the tabular list?
- Diseases of the nervous system (G00-G99), in the block Episodic and paroxysmal disorders (G40-G47).
- What cannot be coded together with G45.8?
- G45.8 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above G45.8 (G45) and apply to it just the same.