January 4, 2013

Your brain’s response to injury

When your brain is injured by stroke, it mounts a significant response to repair the damage and clean up the mess. The result is similar to what happens anywhere when you injure yourself. White blood cells are activated to absorb dead and dying cell debris and carry it away in the bloodstream. Some brain cells form a kind of scar tissue on the edges of the injury. When the stroke is larger than a few cells, a small cavity, which fills with a clear or yellow fluid, forms in the brain. When a red stroke heals, it often stains the brain yellow because the white cells change the color of the red pigment of blood in the process of cleaning up the blood clot. This is similar to the yellow tinge that you may have seen as a bruise heals.

Evidence indicates that part of the healing process for the brain may include some sort of rewiring. The younger you are, the more extensive the rewiring is, and the more rapidly it occurs. What actually happens in the cells is something of a mystery. Whether new cells are formed as part of the process remains unclear, but we do know that new connections are formed.

One of the best-studied examples of rewiring is when patients with normal vision become blind. When their brains are studied several years later, it is clear that the part of the brain that used to respond to visual stimuli now responds to touch in the fingers as the patients read Braille.

TPA: Clot-buster to the rescue.

One Saturday morning, a 75-year-old man was in his yard when he developed a headache, right-side weakness, and confusion. Neighbors called EMS. He was brought to the emergency department of a mid-sized Midwestern hospital.

When first examined, he couldn't lift his right arm, the right side of his face drooped, and his right leg was weak. He was unable to talk and did not seem to understand what was being said to him.

He was taken for a CT scan immediately. No blood was seen on the CT. Because of his symptoms, the doctor taking care of him thought that the problem was probably in the left internal carotid artery or one of its main branches. Because there was no bleeding seen on the CT scan to suggest a red stroke, the doctor assumed this was a white ischemic stroke caused by a blood clot blocking an artery.

The doctor on call gave TPA, tissue plasminogen activator, a commonly used clot-buster for stroke patients, to dissolve the blood clot two hours after the stroke started. The patient had recovered the use of his right leg and could speak and understand words to some extent.

This man owes a lot to his quick-thinking neighbors who got him to an emergency room so fast. After a stroke, brain function generally improves some with time. This is true regardless of the type of stroke. The improvement is more rapid in the first few weeks and months and is thought to be greater if other problems, such as muscle contractures and atrophy of muscles, are prevented. Occupational, speech, and physical therapy all incorporate exercises to aid in rehabilitation. Recent research indicates that such therapy may play an important role in stimulating brain rewiring and regrowth. Naturally, the larger the brain injury is, the less you will be able to recover.

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