10.2

• What is the primary goal of the treatment of a patient who suffered from stroke?

  Save the penumbra.
• Two major types of strokes:

  Cerebral Hemorrhage and Cerebral Ischemia
• Cerebral hemorrhage (bleeding in the brain) occurs when a cerebral blood vessel ruptures and blood seeps into the surrounding neural tissue and damages it
• Bursting aneurysms are a common cause of intracerebral hemorrhage.
• An aneurysm is a pathological balloonlike dilation that forms in the wall of an artery at a point where the elasticity of the artery wall is defective.
• True or False: Aneurysms can be congenital.

  True
• Cerebral ischemia is a disruption of the blood supply to an area of the brain.
• Three main causes of cerebral ischemia are thrombosis, embolism, and arteriosclerosis.
• In thrombosis, a plug called a thrombus is formed and blocks blood flow at the site of its formation.
• A thrombus may be composed of a blood clot, fat, oil, an air bubble, tumor cells, or any combination thereof.
• Embolism is where the plug, called an embolus in this case, is carried by the blood from a larger vessel, where it was formed, to a smaller one, where it becomes lodged; in essence, an embolus is just a thrombus that has taken a trip.
• The walls of blood vessels thicken and the channels narrow, usually as the result of fat deposits; this narrowing can eventually lead to complete blockage of the blood vessels.

  arteriosclerosis
• Ischemia-induced brain damage has two important properties:

  1. It takes a while to develop
  2. Ischemia-induced brain damage does not occur equally in all parts of the brain—particularly susceptible are neurons in certain areas of the hippocampus.
• This is the brain’s most prevalent excitatory neurotransmitter, plays a major role in ischemia-induced brain damage.

  Glutamate
• How is glutamate involved in ischemia-induced brain damage?

  When a blood vessel gets blocked, it starves nearby neurons of blood, causing them to go into overdrive and release too much glutamate, a chemical messenger. This excess glutamate overstimulates receptors on neighboring neurons, especially NMDA receptors. This leads to a flood of sodium (Na+) and calcium (Ca2+) ions into those neurons. (++)
• How is glutamate involved in ischemia-induced brain damage?

  (++) These ions cause two main problems: firstly, they prompt the neurons to release even more glutamate, spreading the harmful effects to more neurons. Secondly, they set off a chain of reactions inside the neurons that eventually kill them.
• An implication of the discovery that excessive glutamate release causes much of the brain damage associated with stroke is the possibility of preventing stroke-related brain damage by blocking the glutaminergic cascade.
• True or False: NMDA-receptor antagonists are effective following acute ischemic stroke. However, to be effective they need to be administered almost immediately after the stroke.

  True
• Two other sorts of treatments have been shown to be effective for stroke:

  • administration of a tissue plasminogen activator (a drug that breaks down blood clots)
  • endovascular therapy (the surgical removal of a thrombus or embolus from an artery).
  • Note: Administration of these treatments within a few hours after the onset of ischemic stroke can lead to better recovery.
• True or False: A non-penetrating TBI is not dangerous.

  False. For the brain to be seriously damaged by a TBI, it is not necessary for the skull to be penetrated.