Brain Stem Stroke
By David Wasielewski
Those of us familiar with strokes and their various descriptions are likely aware of the term Brain Stem stroke. But why is this type of stroke categorized differently from other types? What characteristics make brain stem strokes unique?
Understanding what the brain stem is and what its functions are is the first step in this process. The brain stem was the first part of the human brain to evolve. It was the primitive control center of the nervous system. This area controls the most basic functions necessary for the animal’s survival. Breathing, heartbeat, blood pressure, digestion and swallowing are centered here.
The ability to coordinate movement, withdraw from pain, and react to danger is controlled here. This area coordinates quick reactions like the startle reaction. These types of actions are critical for the survival of primitive organisms so were the first to be developed in the early brain. The startle reaction and withdrawal from pain in humans are incredibly rapid and do not even involve higher level thought or the thinking part of the brain.
Likewise there is no conscious thought involved in the control of our digestive system and blood pressure. As humans and other organisms evolved their brains evolved and enlarged to handle additional functions like high order thinking and emotions. When animals evolve they do not completely redesign already existing parts of their anatomy but rather simply add to what already exists.
So the basic survival functions in the brain remained at the core while higher functions like thought and emotions were added at the outer perimeter or neocortex of the brain mass. The current human brain is outlined in the accompanying diagram. The most complex brain functions occur at the outer edges of the human brain.
Damage to the outer layers of the brain results in loss of higher level functions like reasoning or the ability to control our limbs but damage to the core or brain stem is often far more life threatening. Damage to the brain stem is most likely to impact the most basic survival functions of the brain and body and much more likely to prevent the individual from surviving a stroke or recovering
Brain stem strokes typically have different and more severe symptoms than other strokes. Other strokes typically result in confused thought, reduced function in the limbs and difficulty speaking. Brain Stem strokes symptoms include dizziness, difficulty breathing, difficulty or inability to swallow, loss of coordination, double vision and nausea.
The brain stem is also the area where axons from the rest of the brain converge and pass to the rest of the body. In the most severe cases a patient with brain stem stroke can cause an interruption in these neural pathways resulting in what is commonly known as ‘locked in syndrome’ which leaves the patient completely paralyzed and mute, but able to receive and understand sensory stimuli. Neurologists are often able to differentiate a brain stem stroke from other types simply by observing a patient’s specific symptoms.
Treatment and recovery are more challenging with brain stem strokes because of the loss of more basic life functions. Therapists must address fundamental issues like swallowing and breathing that are not typically learned but are rather instinctive in humans. The process of relearning to use a hand is very different from the process of helping a patient relearn to swallow or breath, which was not a conscious function in their life before the stroke.
Those interested in understanding the effects of a brain stem stroke might read Julian Schnabel’s book “The Diving Bell and the Butterfly”. Julian survived a brain stem stroke which left him paralyzed and able to communicate by blinking his left eye. He wrote the entire book this way providing some very rare insight into what life is like as a ‘locked in’ stroke survivor.
Editor's note. There are many members of The Stroke Network who have had Brainstem strokes. Check out "Brainstem Stroke Talk" on the Message Board.
Copyright © May 2011
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