Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease, is a progressive, fatal neurological disease affecting as many as 20,000 Americans with 5,000 new cases occurring in the United States each year. The disorder belongs to a class of disorders known as motor neuron diseases. ALS occurs when specific nerve cells in the brain and spinal cord that control voluntary movement gradually degenerate. The loss of these motor neurons causes the muscles under their control to weaken and waste away, leading to paralysis. ALS manifests itself in different ways, depending on which muscles weaken first. Symptoms may include tripping and falling, loss of motor control in hands and arms, difficulty speaking, swallowing and/or breathing, persistent fatigue, and twitching and cramping, sometimes quite severely. ALS strikes in mid-life. Men are about one-and-a-half times more likely to have the disease as women. Is there any treatment? There is no cure for ALS; nor is there a proven therapy that will prevent or reverse the course of the disorder. The Food and Drug Administration (FDA) recently approved riluzole, the first drug that has been shown to prolong the survival of ALS patients. Patients may also receive supportive treatments that address some of their symptoms. What is the prognosis? ALS is usually fatal within five years after diagnosis. Rarely, a patient survives 30 yr; 50% die within 3 yr of onset, 20% live 5 yr, and 10% live 10 yr.

Primary lateral sclerosis is a rare neuromuscular disease characterized by progressive muscle weakness in the voluntary muscles. Onset of the disorder generally occurs after age 50. Symptoms may include difficulty with balance, weakness and stiffness in the legs, and clumsiness. Other symptoms may include spasticity (sudden, involuntary muscle spasms) in the hands, feet, or legs which produces slowness and stiffness of movement, dragging of the feet (leading to inability to walk), and facial involvement resulting in dysarthria (poorly articulated speech). The disorder usually begins in the legs, however, it may also begin in the tongue or the hands. PLS belongs to a group of disorders known as motor neuron diseases. It occurs when specific nerve cells in the cerebral cortex that control voluntary movement gradually degenerate, causing the muscles under their control to weaken. The disease—which scientists believe is not hereditary—progresses gradually over a number of years, or even decades, leading to stiffness and weakening of the affected muscles. In PLS, there is no evidence of the degeneration of spinal motor neurons or muscle wasting (amyotrophy) that occurs in a similar disorder called amyotrophic lateral sclerosis or ALS (Lou Gehrig's disease). For the first few years (3-5) after symptoms begin there is a possibility that the true diagnosis is ALS, which can have some of the same symptoms as PLS. For this reason, most neurologists follow the affected individual's clinical course for a few years before making a diagnosis of PLS. Is there any treatment? Treatment for individuals with PLS is symptomatic. Baclofen and tizanidine may reduce spasticity. Quinine or phenytoin may decrease cramps. Physical therapy may help prevent joint immobility, and speech therapy may be useful for patients with dysarthria. What is the prognosis? There is no cure for PLS. The disorder is not considered a fatal disorder.