Stroke

The brainstem is considered to be an extension of the spinal cord and is nestled below the larger part of the brain. It is responsible for critical automatic functions of the body, such as breathing, maintaining blood pressure and heart rate, swallowing, chewing, eye movements, and quick reflexes. It is also the site of major passageways to and from the upper brain and the rest of the body. A stroke that originates in the brain-stem is usually fatal. Fortunately, many strokes involve only part of the brainstem. Double vision, imbalance, trouble swallowing, and weakness or numbness of the face or limbs may result, depending on the part of the brain stem that is affected.

At the back of the brainstem is the ‘‘little brain’’ or cerebellum. The cerebellum coordinates movements and balance, and stores the memory of habitual muscle movements, such as the pattern of the muscle movement used to swing a baseball bat. A stroke that hits the cerebellum can cause unsteadiness, lack of coordination, and awkwardness of the limbs.

Some consider the cerebrum to be the most important part of the brain. It is the most highly developed area of the brain and is what defines people as humans. The cerebrum receives information from all parts of the body, processes the information, and reacts almost instantaneously. A stroke in the cerebrum can affect so many aspects of day-to-day living. To better understand how a stroke survivor can be affected, one should look at all of the parts of the cerebrum.

The cerebrum is divided into two hemispheres, right and left, each controlling the side of the body opposite to it. Each hemisphere controls certain functions, but the two are connected by nerve fibers that allow them to work together or compensate for one another.

The right hemisphere recognizes shapes, angles, proportions, and visual patterns such as people’s faces. The right hemisphere is responsible for emotions, musicality, creativity, and imagination. It also controls a person’s spatial self-awareness. For example, some people who have had their right hemisphere damaged by a stroke no longer feel that their body is their own, and some who are paralyzed on the left side of their body may not recognize their own left hand.

The left hemisphere controls speech, logic, analytical thought, problem solving, language, and movements on the right side of the body. Stroke in the left hemisphere may result in paralysis of the right side of the body and difficulty with communicating and understanding.

The hemispheres are further divided into four lobes. The occipital lobe is the vision center, and a person can be left blind even if the eyes are not damaged when the stroke hits here.

The temporal lobe forms and stores memories, and unless both the right and left temporal lobes are affected, memory loss is not likely to be permanent. Hearing and understanding speech are other functions of the temporal lobe. Wernicke’s area spreads from the temporal lobe into the neighboring parietal lobe, and a stroke here impairs ability to understand language but almost never affects hearing.

The parietal lobes influence the sense of space, perspective, and interpretation. They also contain a strip of sensory cortex that receives and interprets information from the body. The motor cortex is located in front of the sensory cortex, and if it is damaged, paralysis of the face, arm, or leg can occur.

Behavior, anticipation, emotion, thinking, motor function, planning, and speech expression are controlled in the most highly developed part of the brain, the frontal lobes. The frontal lobes influence much of what is considered to be an individual’s personality, and as a result the ability to test the damage to frontal lobes and the degree of impairment is difficult. Stroke can change personality and thinking. A patient may appear to act out of character and the ability to determine what is socially appropriate and what is not may be impaired. Increased difficulty with completing tasks can also be seen. This can be a result of the patient’s forgetting sequences of steps to finish something or inability to send the message to the appropriate muscles to complete a task.

The human brain is a very complicated organ, and stroke damage can be devastating. However, the prognosis is not always so bleak. The brain’s ability to have other parts of it assume lost function and its ability to adapt are just being discovered, bringing greater hopes of recovery for the future.