A transient ischaemic attack, commonly abbreviated to TIA and sometimes called a mini-stroke, is a temporary interruption of blood supply to part of the brain that produces sudden neurological symptoms resembling those of a stroke. Typical symptoms include facial weakness, arm weakness, speech disturbance, visual problems, numbness, dizziness or loss of coordination. The symptoms resolve because the interruption of blood flow is temporary, and by the conventional tissue-based definition there is no persistent brain infarction. A TIA is nevertheless a medical emergency because it is a warning that the person is at increased risk of a subsequent stroke.
The older clinical definition of TIA was largely time-based, describing neurological symptoms that resolved within 24 hours. Modern medicine increasingly uses a tissue-based concept in which TIA refers to transient neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction. The practical distinction matters because symptoms that disappear rapidly cannot safely be assumed to represent a harmless event. Some transient attacks may have associated tissue injury on MRI and are therefore classified differently from a tissue-negative TIA. Emergency assessment is required because clinical symptoms alone cannot establish the underlying tissue status.
A TIA usually results from a temporary arterial blockage. A blood clot may form elsewhere in the circulation, particularly in the heart or large arteries, and travel to a cerebral vessel. Alternatively, a clot or atherosclerotic material may form within an artery supplying the brain. The obstruction temporarily reduces oxygen delivery to a region of nervous tissue, causing neurological dysfunction. If the blockage dissolves or moves and normal blood flow returns before permanent infarction develops, symptoms resolve.
TIA symptoms can resemble virtually any focal neurological deficit caused by stroke, depending on the affected brain region. The NHS identifies sudden facial drooping, arm weakness or numbness and speech difficulty as major symptoms, while other possible manifestations include sudden visual loss, double vision, vertigo, dizziness, vomiting, confusion, difficulty understanding speech, balance problems, coordination difficulties and swallowing impairment. Symptoms generally begin suddenly rather than gradually. The absence of persistent symptoms after a short period does not make the event clinically unimportant.
The major significance of a TIA is its relationship with future stroke risk. A TIA indicates that a vascular or cardiac mechanism capable of interrupting cerebral blood flow may already be present. The highest risk of a full stroke is concentrated in the period shortly after a TIA, which is why rapid investigation and prevention are important. Treatment does not usually focus on treating the neurological symptoms once they have disappeared; instead, clinicians attempt to identify and correct the mechanism responsible for the event and thereby prevent a subsequent stroke.
Assessment after a suspected TIA can include blood-pressure measurement, blood tests for conditions such as diabetes and high cholesterol, ECG testing for atrial fibrillation, carotid ultrasound to look for narrowing of the arteries supplying the brain and selected brain imaging. Specialist assessment should occur rapidly, with NHS guidance stating that suspected TIA patients should be referred to a specialist within 24 hours of symptom onset. The precise investigation depends on the symptoms, medical history and suspected mechanism.
Treatment following TIA is preventive and individualised. Depending on the cause, clinicians may use antiplatelet medicines, anticoagulants, cholesterol-lowering medicines, blood-pressure treatment or other interventions. Significant narrowing of a carotid artery may sometimes require a surgical procedure. Lifestyle measures such as stopping smoking, exercising, maintaining a healthy diet and reducing excessive alcohol intake also reduce vascular risk. The appropriate treatment depends on factors such as age, medical history, vascular findings and whether atrial fibrillation or another embolic source is identified.
A TIA should never be regarded simply as a resolved stroke-like episode that requires no further action. It is an urgent warning event that may identify treatable vascular disease, atrial fibrillation, hypertension, diabetes or other risk factors. If symptoms have occurred within the previous 24 hours, NHS guidance is to call 999 even if they have completely disappeared. Someone who believes they experienced a previous TIA but did not seek medical attention should arrange urgent medical assessment rather than assuming the risk has passed.
