American Medical Association Family Medical Guide - American Medical Association [439]
Multiple Sclerosis
Multiple sclerosis
Myelin is an insulating material that covers nerve fibers throughout the nervous system and promotes rapid passage of electrical impulses along the nerve pathways. In multiple sclerosis, the myelin in random locations in the central nervous system becomes inflamed, swollen, and damaged, which interferes with the normal transmission of electrical impulses.
Although the cause of MS is unknown, researchers think it may result from a combination of genetic susceptibility and environmental factors such as a viral infection that occurs early in life. Some evidence suggests that people who spend the first 15 years of life in a temperate climate have an increased risk of developing MS compared with people who live in the tropics. MS can run in families. Whites are twice as likely as blacks to develop MS, and women are twice as likely as men to develop the disease. Most people who have MS live a normal life span.
Symptoms
The symptoms of MS usually appear between ages 15 and 50. Dizziness is an early symptom of the disease. Later symptoms include blurred vision, numbness and tingling, muscle weakness, fatigue, loss of balance and coordination, tremors (trembling), stiffness, and slurred speech. Initially, symptoms may come and go. In the later stages of the disease, symptoms may worsen. As the disease progresses, a person may develop muscle spasms, urinary tract infections, constipation, loss of bowel and bladder control, sexual dysfunction, depression, or mood swings. Many people experience problems with concentration, memory, and judgment, although their language skills do not change. Symptoms may worsen when the person’s body temperature rises—such as after exercise or a hot bath, during a fever, or when the environmental temperature is high. Repeated episodes of MS can cause progressive nerve damage that significantly limits activity and movement. This nerve damage can make recovery after later episodes more difficult and may lead to permanent disability.
Diagnosis
If you have symptoms of MS, your doctor will recommend that you see a neurologist (a doctor who specializes in treating disorders of the nervous system). A diagnosis of MS is usually based on a person’s neurological history; a neurological examination that includes tests to evaluate the functioning of the nervous system, such as vision, reflexes, hearing, sensation, movement, and balance and coordination; and an MRI (see page 113), which may show damage to the nerve pathways and changes in brain tissue characteristic of MS.
The effects of multiple sclerosis
Because the brain and spinal cord control all parts of the body, damage to the central nervous system from multiple sclerosis can affect many different organs and functions.
The neurologist will order blood tests to help rule out other possible causes of the symptoms, such as vitamin deficiencies, chronic infections, or other inflammatory diseases, such as lupus (see page 920). A neurologist may perform an evoked response test in which electrodes are placed on the person’s head and the electrical activity of the brain is recorded while the person is exposed to various sensory stimuli such as sound or light. Another possible diagnostic test is a lumbar puncture (see page 693), in which a hollow needle is inserted into the spine and a sample of cerebrospinal fluid (the liquid that surrounds the brain and spinal cord) is withdrawn and examined under a microscope to look for inflammatory proteins.
Treatment
Although MS has no cure, medications such as interferon beta, glatiramer, and mitoxantrone can reduce the frequency of episodes with symptoms and slow progression of the disease. It is not yet known how effective these treatments