The National Institute of Neurological Disorders and Stroke estimates that as many as 20,000 Americans have amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. A progressive and rapidly fatal disease, ALS attacks the motor neurons, nerve cells that govern voluntary muscle movement. Eventually, the muscles weaken, twitch and waste away.
Symptoms
Early symptoms of ALS include muscle twitching or cramps and weakness in the hands, legs and ankles. Often people overlook or explain away these early symptoms because there are numerous other possible causes. However, other more unusual symptoms have an early onset, including slurred speech, trouble chewing or swallowing and "foot drop" difficulty lifting the front part of the foot and toes. As the symptoms progress, patients might stumble, have difficulty with fine motor skills like writing by hand, and have trouble speaking clearly. As the disease progresses, the muscle weakness spreads to involve the whole body, and eventually the patient will not be able to breathe without a ventilator.
Risk Factors
According to the National Institute of Neurological Disorders and Stroke, 90 to 95 percent of persons with ALS do not have any clear risk factors. Most cases start in patients between the ages of 40 to 60, and at younger ages, more men than women develop the disease. Dr. Armon reports in the November 2009 issue of "Neurology" that the risk of developing ALS rises with the number of cigarettes smoked and declines with the number of years since quitting smoking.
Genetics
The genetic database Online Mendelian Inheritance in Man says that about 5 to 10 percent of cases of ALS are inherited, and of those, about 20 percent result from inheriting one bad copy of the gene called SOD1 that encodes the enzyme superoxide dismutase. SOD1 is an antioxidant, a molecule that inhibits oxygen from reacting to form unstable compounds such as free radicals, highly chemically reactive molecules that damage cells.
Diagnosis
ALS mimics several other diseases. No single test can definitively prove that someone has ALS, so tests are run to rule out other possible conditions that cause symptoms similar to those of ALS. According to the Mayo Clinic, common tests to rule out other ALS-like conditions include an electromyogram to measure electrical activity in muscles, a study of nerve signal conduction, MRI of the brain and spinal cord, analysis of spinal fluid, blood and urine, and muscle biopsy.
Treatment
There is no cure for ALS, but the drug riluzole slows its progress by decreasing the high levels of the nerve chemical glutamate that can poison nerve cells of people with ALS. The National Institute of Neurological Disorders and Stroke says that riluzole can prolong the time before a patient needs to use a ventilator, and it increases life expectancy by several months. Other medications can relieve symptoms like muscle cramps, pain and fatigue. Physical, occupational and speech therapy can improve the quality of life and prolong a patient's ability to live independently.
References
- National Institute of Neurological Disorders and Stroke: Amyotrophic Lateral Sclerosis Fact Sheet
- Neurology; "Smoking may be considered an established risk factor for sporadic ALS"; C. Amron; November, 2009.
- Online Mendelian Inheritance in Man: Amyotrophic lateral sclerosis
- Mayo Clinic.com: Amyotrophic lateral sclerosis
