Brain ischemia

Brain ischemia is a condition in which there is insufficient bloodflow to the brain to meet metabolic demand. This leads to poor oxygen supply in the brain and may be temporary such as in transient ischemic attack or permanent in which there is death of brain tissue such as in cerebral infarction (ischemic stroke). The symptoms of brain ischemia reflect the anatomical region undergoing blood and oxygen deprivation, and may involve impairments in vision, body movement, and speaking. An interruption of blood flow to the brain for more than 10 seconds causes unconsciousness, and an interruption in flow for more than a few minutes generally results in irreversible brain damage. In 1974, Hossmann and Zimmermann demonstrated that ischemia induced in mammalian brains for up to an hour can be at least partially recovered. Accordingly, this discovery raised the possibility of intervening after brain ischemia before the damage becomes irreversible.