In a patient who had weakness and facial droop that resolved within ten minutes but magnetic resonance imaging shows an infarct in the middle cerebral artery distribution, is this a transient ischemic attack or an acute ischemic stroke?

Diagnosis: Ischemic Stroke

This patient has an ischemic stroke, not a transient ischemic attack, because MRI demonstrates infarction in the MCA territory. 1

Modern Definition of TIA vs. Stroke

The critical distinction between TIA and ischemic stroke is no longer based solely on symptom duration but rather on the presence or absence of infarction on neuroimaging:

• Traditional definition (outdated): TIA was defined as symptoms lasting <24 hours, while stroke was symptoms >24 hours 1

• Current tissue-based definition: Patients with symptoms lasting up to 24 hours who have diffusion-weighted imaging-positive lesions on MRI are now classified as ischemic strokes, not TIAs 1

• Modern TIA definition: A transient episode of neurological dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than 1 hour, and without evidence of infarction 1

Why This Patient Has a Stroke

The presence of infarction on MRI is the determining factor, regardless of symptom duration 1:

• This patient has documented infarction in the MCA distribution on MRI 1
• Even though symptoms resolved within 10 minutes, the imaging evidence of acute infarction definitively classifies this as an ischemic stroke 1
• This classification is widely accepted and should be used for clinical decision-making and outcome reporting 1

Clinical Implications

This distinction has important therapeutic and prognostic implications:

• The patient requires full stroke workup and secondary prevention strategies appropriate for ischemic stroke 1, 2
• Treatment should include antiplatelet therapy, statin therapy, and management of vascular risk factors 3, 2
• The presence of infarction indicates actual tissue damage occurred, which carries different prognostic implications than true TIA 1, 2

Common Pitfall to Avoid

Do not rely solely on symptom duration to distinguish TIA from stroke 1. Up to one-third of patients with symptoms lasting <24 hours have been found to have infarction on modern neuroimaging 1. Always obtain brain imaging (preferably MRI with diffusion-weighted imaging) to make the definitive diagnosis 1, 4.