ALS is a rapidly progressive, fatal, neuromuscular disease. As noted above, ALS is caused by degeneration of the lower motor neurons (the nerves that travel from the brainstem and spinal cord out to the muscles), which results in muscle wasting, as well as the upper motor neurons. Fifty-percent of ALS patients die from respiratory failure or pneumonia within three to five years of diagnosis.
However, there are some slowly progressing forms of ALS that are difficult to distinguish from PLS. In fact, up to 10% of ALS patients survive more than ten years. In addition, improved medical care is resulting in longer and more productive lives for all ALS patients. For more information on ALS, please see the ALS Fact Sheet by the National Institute of Neurological Disorders and Stroke.