Embolic stroke of undetermined source

Embolic stroke of undetermined source (ESUS) is an embolic stroke, a type of ischemic stroke, with an unknown origin, defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources. As such, it forms a subset of cryptogenic stroke, which is part of the TOAST-classification. The following diagnostic criteria define an ESUS:

• Stroke detected by CT or MRI that is not lacunar
• No major-risk cardioembolic source of embolism
• Absence of extracranial or intracranial atherosclerosis causing 50% luminal stenosis in arteries supplying the area of ischaemia
• No other specific cause of stroke identified (e.g., arteritis, dissection, migraine/vasospasm, drug misuse)