Amyotrophic lateral sclerosis
| What is amyotrophic lateral sclerosis? |
Amyotrophic lateral sclerosis (ALS) — widely known as Lou Gehrig's disease — causes degeneration of the nerve cells in certain regions of the brain and spinal cord that control your voluntary muscles. Eventually, you lose your ability to move your limbs and the muscles you need to breathe.
The causes of the disease remain elusive. Although there's no reversing the progression of ALS, advances in treatment have meant that many who have the disease are living longer. Each year about 5,000 Americans are newly diagnosed with ALS, and about 20,000 Americans have the disease.
ALS first gained widespread public attention in the United States in 1939, when it ended the career of Hall of Fame baseball player Lou Gehrig of the New York Yankees.
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| Signs and symptoms |
ALS commonly begins in one part of your body and progresses slowly. Gradual death of nerve cells saps muscles of their control. Early signs and symptoms of ALS include:
- Muscle cramps and twitching in your arms, shoulders and tongue
- Slow loss of strength and coordination in one or more of your limbs
- Weakness in your feet and ankles, resulting in a stiff and clumsy gait and in dragging your feet
- Difficulty swallowing, speaking or breathing
- Fatigue in combination with the above signs and symptoms
Eventually, ALS paralyzes the muscles you use to breathe. Most people with ALS die of respiratory failure. Sometimes, people with ALS stop breathing because they aspirate food and oral secretions that they can't swallow.
| Causes |
The basic units of your central nervous system (brain and spinal cord) are nerve cells (neurons). These cells communicate with one another and send and receive signals throughout your body. Each neuron consists of a cell body, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). Nerve cells communicate with adjacent nerve cells at contact points called synapses.
Nerve signals provide information to your brain through your senses, they communicate with your involuntary muscles — the ones that control activities such as digestion, sexual function and heartbeat — and they activate your voluntary muscles, through your peripheral nervous system.
ALS is a disease that involves death of motor neurons — nerve cells that control voluntary muscles. These are the muscles you use to move your limbs, face, neck and torso and to talk, chew, swallow and breathe. In ALS, both upper motor neurons, located in your brain, and lower motor neurons, located in your spinal cord, gradually die. Over time, this results in your voluntary muscles no longer receiving messages. Your muscles become weak and begin to waste away (atrophy).
ALS occurs in two forms:
- Sporadic ALS. In 90 percent or more of cases, ALS appears to occur randomly, with no identifiable cause and no clearly associated risk factors.
- Familial ALS. Up to 10 percent of ALS cases appear to be inherited. In 1993, scientists identified a gene mutation in an enzyme known as superoxide dismutase 1 (SOD1). The SOD1 enzyme is an antioxidant. Antioxidants are substances that protect your body by neutralizing free radicals, which are byproducts of your cells' normal metabolism. Free radicals can damage the structure of your cells. Because the SOD1 defect is responsible for only about 20 percent of cases of familial ALS, other genetic defects are responsible for other cases of familial ALS.
| Risk factors |
Although most cases of ALS occur from no apparent cause, about 5 percent to 10 percent of people who have ALS inherit it. Inherited ALS may strike at a younger age and in consecutive generations. If you're the first person in your family to have ALS, you likely don't have an inherited form, and your children aren't at a greater risk.
Noninherited ALS often develops between ages 40 and 60, although the disease affects people of all ages. Men are somewhat more frequently affected than women are.
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| When to seek medical advice |
If you've noticed slow, progressive weakness in one of your limbs, accompanied by twitching and cramping of the affected muscles, see your doctor to determine if there may be a neurologic cause such as ALS. Although there's no treatment to reverse the course of ALS, other neurologic conditions that may mimic some of the signs and symptoms of ALS are treatable. The sooner you see your doctor, the sooner a diagnosis and treatment decisions can be made.
| Screening and diagnosis |
ALS is difficult to diagnose early because it may appear similar to other neurologic diseases. Your doctor may refer you to a specialist in nerve disorders (neurologist) if you have signs and symptoms of a neurologic condition.
Diagnosing ALS first involves reviewing your family's medical history and your signs and symptoms. You'll then have a physical examination that may include some basic in-office testing of your nerves and muscles. Additionally, you'll undergo a variety of tests, including tests to rule out other conditions. These diagnostic tests may include:
- Electromyogram (EMG). Electromyography measures the tiny electrical discharges produced in muscles. A thin-needle electrode is inserted into the muscles your doctor wants to study. An instrument records the electrical activity in your muscle at rest and as you contract the muscle.
- Nerve conduction study (NCS). In a variation of electromyography, two electrodes are taped to your skin above a nerve to be studied. A small shock is passed through the nerve to measure the speed of nerve signals.
- Imaging. You may undergo tests such as a magnetic resonance imaging (MRI) or computerized tomography (CT) scan to produce images of your brain and spinal cord. These tests can help your doctor determine if causes other than ALS may be causing your signs and symptoms.
- Spinal tap (lumbar puncture). This test analyzes the fluid surrounding your brain and spinal cord (cerebrospinal fluid). You typically lie on your side with your knees drawn up to your chest. A local anesthetic is injected in an area over your lower spine to reduce any discomfort from the procedure. Then a needle is inserted into your spinal canal, and fluid is collected. Tests on this fluid indicate the number and types of white blood cells, the level of sugar, and the levels and types of proteins. Additional tests on this fluid can indicate evidence of bleeding, infection and abnormal cells.
- Blood and urine tests. Analyzing samples of your blood and urine in the laboratory may help your doctor eliminate other possible causes of your signs and symptoms.
- Muscle biopsy. If your doctor believes you may have a muscle disease other than ALS, you may undergo a muscle biopsy. Under local anesthesia, your doctor removes a small portion of tissue to be analyzed in the laboratory.
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| Treatment |
Because there's no reversing the course of ALS, treatments mainly involve efforts to make you more comfortable and independent and to slow the progression of symptoms. Treatments may involve many professionals, including doctors, therapists, nutritionists, social workers and hospice nurses, and may include:
- Medications. The drug riluzole (Rilutek) is the first and only medication approved by the Food and Drug Administration for slowing ALS. The drug appears to slow the disease's progression in some people, perhaps by reducing glutamate levels, and prolong life by a few months. Your doctor may also prescribe medications to provide relief from muscle cramps and constipation and to reduce fatigue, excessive salivation and excessive phlegm.
- Physical and occupational therapy. A physical therapist can recommend low-impact exercises to maintain your muscle strength and range of motion as long as possible, helping you preserve a sense of independence. An occupational therapist can help you become accustomed to a brace, walker or wheelchair and may be able to suggest devices such as ramps that make it easier for you to get around.
- Speech therapy. Because ALS affects the muscles you use to speak, communicating clearly becomes an issue as the disease progresses. A speech therapist can help teach techniques to make your speech more clearly understood. Later in the disease, devices such as speech synthesizers and computers may help you communicate.
- Nutritional support. A nutritionist can advise you on foods that are nutritious but easy to swallow, helping you avoid choking on food or accidentally inhaling food or liquids into your lungs. As the disease progresses and you have greater difficulty swallowing, a feeding tube inserted into your stomach may be the best way to receive nutrition and avoid choking.
- Breathing assistance. ALS progressively weakens the muscles you need for breathing, making it more difficult to breathe. At first, you may benefit from a device that makes it easier for you to breathe during the night. Some devices, such as masks or nose inserts, fit over your face and are easy to use or remove. The mask or nose insert is attached to a portable machine that provides air pressure to inflate your lungs. You can also use these devices during the day. As breathing muscles weaken further, you may need the full-time help of a respirator to both inflate and deflate your lungs.
| Coping skills |
Having ALS greatly changes your lifestyle and that of your family and creates a high financial burden. Fortunately, you can share your concerns in a support group with others who have ALS and their family members. You can find out the location of the nearest ALS support group through your doctor or by contacting the Amyotrophic Lateral Sclerosis Association of America.
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— January 2, 2003 —