Amyotrophic Lateral Sclerosis (ALS)
Amyotrophic lateral sclerosis (or ALS) is a progressive disorder that affects over five thousand Americans each year. The average survival time from the onset of the symptoms is three to five years. This condition, that affects motor neurons, costs Americans about $300 million annually.
ALS is commonly known as Lou Gehrig’s disease and affects neurons that control voluntary muscle movements. For reasons that are not yet completely understood, motor neurons in the brain and central nervous system begin to disintegrate. The result of this is that the signals from the brain are not carried to the body by these damaged nerves. This, in turn, weakens and deteriorates the muscles because of the lack in stimulation and the subsequent disuse.
The first signs of this progressive paralysis are usually seen in hands and feet, including weakness in the legs, difficulty when walking and clumsiness of the hands. Eventually, all muscles under voluntary control are affected. This includes the muscles of the respiratory system and death usually results from pneumonia or respiratory failure. However, despite the paralysis, the mind and senses remain intact.
There is not a specific test to identify ALS, but through muscle biopsies, blood studies, electrical tests of muscle activity, CT and MRI scans, and X-rays of the spinal cord help in identifying the disease by ruling out others. Since the causes of the disease remain unknown, diagnosis is still often a difficult matter. Some potential causes or contributors are glutamate toxicity, oxidative stress, environmental factors and an autoimmune response.
In over 90% of the cases, the condition is sporadic, arising in individuals with no family history of ALS. In the other 10% of the cases, it is familial, transmitted to family members because of gene defects.
By now, scientists have identified several genes that are involved in causing some form of ALS. The most common and well studied of these mutations, is the one on the gene for superoxide dismutase on chromosome 21. It is hoped that by studying this and other genes, an insight could be acquired in the sporadic form of the condition as well.
Once the condition has been diagnosed, physical therapy and rehabilitation methods help in strengthening the unused muscles. Specific problems, such as twitching and muscle weakness, can be alleviated by various drugs. Sadly, there is no real cure. There is an anti-glutamate drug that moderately slows the progression of the disease and several additional drugs are currently under study. Protecting or regenerating motor neurons, other more potent drugs and stem cell therapies may someday provide significant hope for patients.