Amyotrophic lateral sclerosis (ALS) is a fatal neruomuscular disease that is characterized by progressive muscle weakness resulting in paralysis. This degenerative disease of the nervous system affects the brain cells (motor neurons) that carry impulses from the brain and spinal cord to the muscles. Degeneration of these neurons causes muscle weakness, and muscle loss, usually starting in the hands and arms and spreading to other parts of the body. Difficulty with speaking, swallowing, and breathing ensues, and death usually follows within 3 to 5 years. Onset of ALS commonly occurs between the ages of 35 and 65 and has a slightly higher frequency of occuring more often in men than in women.
             ALS is usually characterized by both upper and lower motor neuron damage. Symptoms of upper motor neuron damage include stiffness, muscle twitching, and muscle shaking. Symptoms of lower motor neuron damage include muscle weakness and muscle atrophy. Most ALS patients have limb-onset ALS and first notice muscle weakness in either the arms or the legs (32 percent in the arms and 36 percent in the legs). Bulbar ALS presents with speaking and swallowing difficulties as the first symptoms. Those patients with bulbar-onset ALS generally have a faster disease progression than do limb-onset patients. Limb-onset patients eventually develop bulbar symptoms as their disease progresses.
             Because early ALS symptoms may be similar to a number of other neuromuscular diseases, ALS is diagnosed through a process of elimination. Diagnostic tests include MRI (magnetic resonance imaging), EMG (electromyogram), muscle biopsy, and blood tests. In order for a definitive diagnosis of ALS to be made, damage must be evident in both upper and lower motor neurons. When three limbs are sufficiently affected, the diagnosis is ALS. The diagnosis of ALS typically takes weeks or months.
             There are three different types of ALS. The most common type is sporadi...