Diagnostic and prognostic utility of brain collaterals in acute ischaemic stroke : current knowledge and insights on treatment decision-making

Stroke is a leading cause of death and disability worldwide. The advent of acute reperfusion therapy, intravenous throm-bolysis and endovascular thrombectomy, has revolutionised the field of stroke medicine, and neurology in general. Re-cent studies have implicated a major role of cerebral collaterals in the trajectory of acute ischemic stroke patients receiving reperfusion therapy. Collaterals sustain blood supply to the tissue in the setting of acute ischaemia which prevents further expansion of the hypoperfused tissue, playing an important role in determining outcomes after acute ischaemic stroke. The use of collateral assessment in routine practice in acute ischaemic stroke, let alone in reperfusion therapy, is far from universal and limited. Future work in embedding collateral assessment in standards of care in acute stroke and management is warranted. This article provides a comprehensive update on the diagnostic and prognostic utility of col-laterals in acute ischaemic stroke and recommendations on collateral-based decision making in acute stroke and steps that can be taken for its rapid uptake in clinical practice.