2026 ICD-10-CM Diagnosis Code G45.9Transient cerebral ischemic attack, unspecified

ICD-10-CM Codes›G00–G99›G40-G47›G45

ICD-10-CM G45.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G45.9 is a billable ICD-10-CM diagnosis code for transient cerebral ischemic attack, unspecified. 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
G45.9
Billable Status
Yes — Valid for Submission
Code Describes
Transient cerebral ischemic attack, unspecified
Short Description
Transient cerebral ischemic attack, unspecified
Same as the full description in the CMS dataset.
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 CodeG45.9Transient cerebral ischemic attack, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arteriospasm
  • Intermittent cerebral ischemia
  • Recurrent transient cerebral ischemic attack
  • Spasm of cerebral arteries
  • Stroke/transient ischemic attack monitoring first letter
  • Stroke/transient ischemic attack monitoring invitation
  • Stroke/transient ischemic attack monitoring second letter
  • Stroke/transient ischemic attack monitoring status
  • Stroke/transient ischemic attack monitoring third letter
  • Stroke/transient ischemic attack monitoring verbal invitation
  • Transient cerebral ischemia
  • Transient cerebral ischemia due to atrial fibrillation
  • Transient ischemic attack co-occurrent with subarachnoid hemorrhage
  • Transient ischemic attack due to embolism
  • Vasospasm

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Spasm of cerebral artery
  • TIA
  • Transient cerebral ischemia NOS

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.

    • Angiospasm(peripheral) (traumatic) (vessel)
      • cerebral
    • Attack, attacks
      • transient ischemic (TIA)
    • Claudication(intermittent)
      • cerebral (artery)
    • Disease, diseased
      • angiospastic
        • cerebral
    • Ischemia, ischemic
      • cerebral (chronic) (generalized)
        • intermittent
    • Ischemia, ischemic
      • cerebral (chronic) (generalized)
        • transient
    • Spasm(s), spastic, spasticity
      • artery
        • cerebral
    • Spasm(s), spastic, spasticity
      • cerebral (arteries) (vascular)

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

  • Arteriospasm

    an abnormal spasm of an artery.

  • Coronary Vasospasm

    sudden coronary artery smooth muscle contraction leading to lumen constriction and decreased blood flow.

  • Vasospasm

    sudden and often, paroxysmal contractions of the muscular wall of blood vessels.

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 G45.9 to ICD-9-CMHistory

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

ICD-9-CM
435.9 Trans cereb ischemia NOS
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 G45.9Overview

Is G45.9 (Transient cerebral ischemic attacks and related syndromes) a billable code?

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

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

Under the General Equivalence Mappings, transient cerebral ischemic attack, unspecified converts to ICD-9-CM 435.9 (trans cereb ischemia NOS). 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.