11.44: Nervous System Diseases

Why get vaccinations?

Like this girl, many people are a little afraid of needles. But this is no reason to avoid vaccinations. Vaccinations can help you avoid serious diseases. For example, a vaccination to prevent meningitis, a serious infection of the nervous system, is now available.

Diseases of the Nervous System

The nervous system controls sensing, feeling, and thinking. It also controls movement and just about every other body function. That’s why problems with the nervous system can affect the entire body. Diseases of the nervous system include brain and spinal cord infections. Other problems of the nervous system range from very serious diseases, such as tumors, to less serious problems, such as tension headaches. Some of these diseases are present at birth. Others begin during childhood or adulthood.

Central Nervous System Infections

When you think of infections, you probably think of an ear infection or strep throat. You probably don’t think of a brain or spinal cord infection. But bacteria and viruses can infect these organs as well as other parts of the body. Infections of the brain and spinal cord are not very common. But when they happen, they can be very serious. That’s why it’s important to know their symptoms.

Encephalitis

Encephalitis is a brain infection (Figure below). If you have encephalitis, you are likely to have a fever and headache or feel drowsy and confused. The disease is most often caused by viruses. The immune system tries to fight off a brain infection, just as it tries to fight off other infections. But sometimes this can do more harm than good. The immune system’s response may cause swelling in the brain. With no room to expand, the brain pushes against the skull. This may injure the brain and even cause death. Medicines can help fight some viral infections of the brain, but not all infections.

Figure \(\PageIndex{1}\): This scan shows a person with encephalitis.

Meningitis

Meningitis is an infection of the membranes that cover the brain and spinal cord. If you have meningitis, you are likely to have a fever and a headache. Another telltale symptom is a stiff neck. Meningitis can be caused by viruses or bacteria. Viral meningitis often clears up on its own after a few days. Bacterial meningitis is much more serious (Figure below). It may cause brain damage and death. People with bacterial meningitis need emergency medical treatment. They are usually given antibiotics to kill the bacteria.

Figure \(\PageIndex{2}\): These bacteria, shown at more than 1,000 times their actual size, are the cause of bacterial meningitis. Despite their tiny size, they can cause very serious illness.

A vaccine to prevent meningitis recently became available. It can be given to children as young as two years old. Many doctors recommend that children receive the vaccine no later than age 12 or 13, or before they begin high school.

Reye's Syndrome

A condition called Reye’s syndrome can occur in young people that take aspirin when they have a viral infection. The syndrome causes swelling of the brain and may be fatal. Fortunately, Reye’s syndrome is very rare. The best way to prevent it is by not taking aspirin when you have a viral infection. Products like cold medicines often contain aspirin. So, read labels carefully when taking any medicines (Figure below).

Figure \(\PageIndex{3}\): Since 1988, the U.S. Food and Drug Administration has required that all aspirin and aspirin-containing products carry a warning about Reye’s syndrome.

Other Nervous System Diseases

Like other parts of the body, the nervous system may develop tumors. A tumor is a mass of cells that grows out of control. A tumor in the brain may press on normal brain tissues. This can cause headaches, difficulty speaking, or other problems, depending on where the tumor is located. Pressure from a tumor can even cause permanent brain damage. In many cases, brain tumors can be removed with surgery. In other cases, tumors can’t be removed without damaging the brain even more. In those cases, other types of treatments may be needed.

Cerebral palsy is a disease caused by injury to the developing brain. The injury occurs before, during, or shortly after birth. Cerebral palsy is more common in babies that have a low weight at birth. But the cause of the brain injury is not often known. The disease usually affects the parts of the brain that control body movements. Symptoms range from weak muscles in mild cases to trouble walking and talking in more severe cases. There is no known cure for cerebral palsy.

Epilepsy is a disease that causes seizures. A seizure is a period of lost consciousness that may include violent muscle contractions. It is caused by abnormal electrical activity in the brain. The cause of epilepsy may be an infection, a brain injury, or a tumor. The seizures of epilepsy can often be controlled with medicine. There is no known cure for the disease, but children with epilepsy may outgrow it by adulthood.

A headache is a very common nervous system problem. Headaches may be a symptom of serious diseases, but they are more commonly due to muscle tension. A tension headache occurs when muscles in the shoulders, neck, and head become too tense. This often happens when people are “stressed out.” Just trying to relax may help relieve this type of headache. Mild pain relievers such as ibuprofen may also help.

Figure \(\PageIndex{4}\): Sometimes relaxation is the best “medicine” for a tension headache and to help muscles get rid of pain.

A migraine is a more severe type of headache. It occurs when blood vessels in the head dilate, or expand. This may be triggered by certain foods, bright lights, weather changes, or other factors. People with migraines may also have nausea or other symptoms. Fortunately, migraines can often be relieved with prescription drugs.

There are many other nervous system diseases. They include multiple sclerosis, Huntington’s disease, Parkinson’s disease, and Alzheimer’s disease. However, these diseases rarely, if ever, occur in young people. Their causes and symptoms are listed below (Table below). The diseases have no known cure, but medicines may help control their symptoms.

Disease	Cause	Symptoms
Multiple sclerosis	The immune system attacks and damages the central nervous system so neurons cannot function normally.	Muscle weakness, difficulty moving, problems with coordination, difficulty keeping the body balanced
Huntington’s disease	An inherited gene codes for an abnormal protein that causes the death of neurons.	Uncontrolled jerky movements, loss of muscle control, problems with memory and learning
Parkinson’s disease	An abnormally low level of a neurotransmitter affects the part of the brain that controls movement.	Uncontrolled shaking, slowed movements, problems with speaking
Alzheimer’s disease	Abnormal changes in the brain cause the gradual loss of most normal brain functions.	Memory loss, confusion, mood swings, gradual loss of control over mental and physical abilities

Summary

• The nervous system can be affected by infections, such as encephalitis or meningitis.
• Other nervous system diseases include tumors, cerebral palsy, epilepsy, and migraines.

Explore More

Use the resource below to answer the questions that follow.

• Neurological Disorders at http://www.youtube.com/watch?v=7ivWFEyiahg (9:14)

1. What are three examples of neurological disorders?
2. What kinds of deficits can neurological disorders cause?
3. How does blood supply affect strokes?
4. List three signs of a TIA.
5. What is the affect of multiple sclerosis? What body systems are involved?

Review

1. What is meningitis? What are the symptoms? What should you do if you have these symptoms?
2. What is cerebral palsy? What are its symptoms?
3. Compare and contrast tension headaches and migraine headaches.
4. Explain why young people should not take aspirin when they have the flu, which is caused by viruses.