The brain, like all body systems, is highly complex and highly specialized. Though we don’t know everything there is to know about how the brain works, we do know that brain cells are essentially irreplaceable. That is, whereas most of the other cells in the body can regenerate, the individual cells that are the working units of the brain, called neurons, cannot.
Brain cells rely on oxygen and glucose (sugar) for energy and proper function. Any prolonged disruption of the supply of either of these chemicals can lead to cell death. In a stroke (cerebral vascular accident or CVA), the blood supply to the brain cells is disrupted. No blood flow means no glucose or oxygen. This results in a loss of neurons and function in that area of the brain.
In about 85% of cases, the stroke is caused by a blockage of blood flow through the arteries supplying the brain. Usually, small blood clots or cholesterol-laden plaques in the arteries cause the blockage.
In the other 15 percent of cases there is hemorrhage. This means a blood vessel has burst and is bleeding into the cells. This not only disrupts the energy supply to these cells, but the pressure of the bleeding chokes them out.
The brain’s neurons are departmentalized into specific locations, each region performing a specific function. Some are for movement, some for sensation, some for speech, etc. Any bodily function that the brain controls could be disrupted by a stroke. For example, if the blood supply was interrupted to the area of the brain that initiates moving an arm, one would experience weakness or loss of movement in that arm.
The symptoms of a stroke will depend on where the blockage or bleeding has occurred within the brain and which specialized cells are affected. They may include: weakness, numbness or tingling in the face, an arm, or a leg; sudden, severe headache; unexplained dizziness, unstable walking or falling; loss or slurring of speech, trouble talking or understanding what others are saying; sudden dimness or loss of vision, particularly in one eye; double vision; facial drooping.
Since most strokes are due to a blockage of blood flow, seek treatment immediately if you are experiencing symptoms that are suspicious for a stroke. Emergency medicines and procedures are available that can help to quickly restore the blood flow to the affected brain cells. Lost time getting emergency treatment can be the difference between a temporary loss of function and a permanent loss.
Equally important to emergency treatment of an acute stroke are the measures we can take to reduce our risk of a stroke. The major risk factors are high blood pressure, smoking, high cholesterol, and uncontrolled diabetes (high sugar). These conditions mainly contribute to the buildup of plaque within the blood vessels (hardening of the arteries) or to the weakening of the blood vessels resulting in bleeding. Individuals who have heart disease or who have had a previous mini-stroke (TIA) are at higher risk as well.
Regular checkups with your doctor can identify your risk factors and stimulate discussion of appropriate treatment if needed. If you have high blood pressure, high cholesterol, or high blood sugar, get these under control. If you smoke, take steps to quit now. Daily exercise helps to control your blood pressure, your cholesterol, and your sugar. Avoid foods that are high in saturated fat and cholesterol. Eat less salt to help lower your blood pressure.
The content in this column is for informational purposes only. Consult your physician for appropriate individual treatment. Dr. Reynolds practices Family Medicine in Chesterfield.