The extent of damage depends on the duration and severity of the ischemia. If ischemia persists for more than 5 minutes with
perfusion below 5% of normal, some neurons will die. However, if ischemia is mild, the damage will occur slowly and may take up to 6 hours to completely destroy the brain tissue. In case of severe ischemia lasting more than 15 to 30 minutes, all of the affected tissue will die, leading to infarction. The rate of damage is affected by temperature, with
hyperthermia accelerating damage and
hypothermia slowing it down and other factors.
