2026 ICD-10-CM Diagnosis Code G45.8Other transient cerebral ischemic attacks and related syndromes

ICD-10-CM Codes›G00–G99›G40-G47›G45

ICD-10-CM G45.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G45.8 is a billable ICD-10-CM diagnosis code for other transient cerebral ischemic attacks and related syndromes. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Transient cerebral ischemia.

Code Identity

ICD-10-CM Code
G45.8
Billable Status
Yes — Valid for Submission
Code Describes
Other transient cerebral ischemic attacks and related syndromes
Short Description
Oth transient cerebral ischemic attacks and related synd
Parent Code
G45
Transient cerebral ischemic attacks and related syndromes

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG45Transient cerebral ischemic attacks and related syndromes
This CodeG45.8Other transient cerebral ischemic attacks and related syndromes

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute cerebral ischemia
  • Arterial steal syndrome
  • Carotid territory transient ischemic attack
  • Cerebral steal syndrome
  • Left subclavian steal syndrome
  • Right subclavian steal syndrome
  • Subclavian steal syndrome
  • Vertebrobasilar territory transient ischemic attack

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Attack, attacks
      • transient ischemic (TIA)
        • specified NEC
    • Insufficiency, insufficient
      • cerebrovascular (acute)
        • with transient focal neurological signs and symptoms
    • Ischemia, ischemic
      • cerebral (chronic) (generalized)
        • recurrent focal
    • Syndrome
      • steal
        • subclavian
    • Syndrome
      • subclavian steal

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS012
Transient cerebral ischemia
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Subclavian Steal Syndrome

    a clinically significant reduction in blood supply to the brain stem and cerebellum (i.e., vertebrobasilar insufficiency) resulting from reversal of blood flow through the vertebral artery from occlusion or stenosis of the proximal subclavian or brachiocephalic artery. common symptoms include vertigo; syncope; and intermittent claudication of the involved upper extremity. subclavian steal may also occur in asymptomatic individuals. (from j cardiovasc surg 1994;35(1):11-4; acta neurol scand 1994;90(3):174-8)

  • Subclavian Steal Syndrome

    an uncommon neurovascular condition seen with exertion of the upper extremity. it is usually caused by atherosclerotic stenosis or occlusion of the subclavian artery proximal to the origin of the vertebral artery. in order to maintain adequate perfusion of the arm during exercise on the affected side, the narrowed subclavian artery siphons off retrograde blood flow from the ipsilateral vertebral artery. this is possible due to lower blood pressure distal to the site of narrowing and collateral circulation through the circle of willis. affected individuals may remain asymptomatic until the oxygen demand generated from upper extremity exercise requires a large enough compensatory volume of blood to be diverted from the vertebral artery to provoke vertebrobasilar insufficiency and its accompanying neurological sequelae. presenting clinical signs may include pain or numbness of the affected arm (with diminished pulses and a brachial systolic blood pressure differential of greater than 20 mmhg as compared to the opposite arm), vertigo, tinnitus, dysarthria, diplopia and syncope. notably, unlike cerebral infarction, the clinical course does not lead to chronic neurologic disability. prognosis for recovery of normal anterograde circulation is favorable following endovascular or surgical intervention.

Patient EducationClinical

Transient Ischemic Attack

A transient ischemic attack (TIA) is a stroke that lasts only a few minutes. It happens when the blood supply to part of the brain is briefly blocked. Symptoms of a TIA are like other stroke symptoms, but do not last as long. They happen suddenly, and include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G45.8 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
435.2 Subclavian steal syndrom
Approximate The match is approximate rather than exact.
ICD-9-CM
435.8 Trans cereb ischemia NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G45.8Overview

Is G45.8 (Transient cerebral ischemic attacks and related syndromes) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other transient cerebral ischemic attacks and related syndromes on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of G45.8?

Under the General Equivalence Mappings, other transient cerebral ischemic attacks and related syndromes converts to ICD-9-CM 435.2 (subclavian steal syndrom) and 435.8 (trans cereb ischemia NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.