In a related article, Perry and colleagues discuss the management of patients with transient ischemic attack (TIA) or minor stroke. (1) Experts estimate that 41000 people experience such events annually in Canada (Jessalyn Holodinsky, University of Calgary: personal communication, 2022). Symptomatic cerebral ischemia occurs on a spectrum, from mild and transient to severe and fatal. By definition, TIA is the mildest form of symptomatic cerebral ischemia, typically lasting 15 minutes or less, (2) but is formally defined by the full resolution of all neurologic symptoms and signs within 24 hours. However, many patients labelled as having had a TIA have actually had a minor stroke, as they either have persisting minor neurologic symptoms and signs that have been missed, or their symptoms have resolved but brain imaging still shows evidence of ongoing ischemia. (3,4) Therefore, it is not clinically useful to distinguish between TIA and minor stroke. Best practice is to investigate quickly and intervene rapidly to prevent disabling ischemic stroke, which requires the use of simple risk stratification combined with timely neurovascular imaging.
Minor cerebral ischemic events are associated with a higher risk of a future more serious illness. A 2007 study found that, before the era of urgent treatment, patients with TIA or minor stroke had an estimated risk of recurrent ischemic stroke in the next 90 days of 17%. (5) However, urgent assessment and treatment of TIA or minor stroke can reduce this risk to 2%-3%. (6,7) It is critical to understand that brain ischemia is a time-sensitive diagnosis that warrants time-sensitive action. As in the assessment of chest pain, clinical symptoms alone cannot be used to make a diagnosis; electrocardiography (ECG) and serum troponin are used in conjunction with clinical symptoms to make the diagnosis and guide management. Similarly, clinical symptoms and urgent brain and neurovascular imaging are all needed to accurately assess TIA and minor stroke. (8)
A TIA or minor stroke is initially a working diagnosis. Clinicians should identify if the patient has had motor or speech symptoms. If so, they are at higher risk of progressive or early recurrent stroke over the ensuing 90 days; if not, they are lower risk. We respectfully disagree with Perry and colleagues that it is acceptable to defer neurovascular imaging to the outpatient setting. (1) High-risk patients should be sent for brain and neurovascular imaging immediately, as half of recurrent stroke events occur within the first 48 hours, many overnight during sleep. (9) Extracranial carotid, vertebral artery or intracranial atherosclerosis are major causes of early recurrence, and there are clear, effective treatments.
Computed tomography (CT) or magnetic resonance angiography (MRA) of the cerebral arteries (from arch to vertex) should be ordered, as normal scans have very high negative predictive value for early recurrence, meaning that one can safely send a patient home, typically on antiplatelet therapy with planned follow-up...