section_path: Classification/Ischemic
section_name: Ischemic
paragraph_text: Ischemic
  
  During ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction of the brain tissue in that area. There are four reasons why this might happen:
  
  Stroke without an obvious explanation is termed cryptogenic stroke (idiopathic); this constitutes 30–40% of all cases of ischemic stroke.
  
  There are classification systems for acute ischemic stroke. The Oxford Community Stroke Project classification (OCSP, also known as the Bamford or Oxford classification) relies primarily on the initial symptoms; based on the extent of the symptoms, the stroke episode is classified as total anterior circulation infarct (TACI), partial anterior circulation infarct (PACI), lacunar infarct (LACI) or posterior circulation infarct (POCI). These four entities predict the extent of the stroke, the area of the brain that is affected, the underlying cause, and the prognosis.
  
  The TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification is based on clinical symptoms as well as results of further investigations; on this basis, stroke is classified as being due to
  
  (1) thrombosis or embolism due to atherosclerosis of a large artery,
  
  (2) an embolism originating in the heart,
  
  (3) complete blockage of a small blood vessel,
  
  (4) other determined cause,
  
  (5) undetermined cause (two possible causes, no cause identified, or incomplete investigation).
  
  Users of stimulants such as cocaine and methamphetamine are at a high risk for ischemic stroke.