<s>[INST] What is a stroke? [/INST] Stroke is restricted or interrupted blood supply to the brain. Stroke can occur when blood vessels within the brain get blocked or rupture. Lack of oxygen supply to the brain kills brain cells. Strokes can be fatal and in some cases, a person may enter the state of coma immediately after a severe stroke. Source: MEDIFEE. Link: https://www.medifee.com/faq/stroke#1. Field: Neurology. Disease: Stroke </s>