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.
Source: Wikipedia — Embolic stroke of undetermined source (CC BY-SA 4.0)