What Is Amyotrophic Lateral Sclerosis? Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disorder of the nervous system. It is also known as Lou Gehrig’s disease. ALS attacks motor neurons, which are nerve cells in the brain and spinal cord. These cells send messages to muscles throughout the body. In ALS, the motor neurons die. The ability of the brain to start and control muscle movement is lost. As a result, muscles gradually weaken. In time, most muscles a

Myasthenia Gravis Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. Symptoms vary in type and intensity. The hallmark of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Muscles that control eye and eyelid movements, facial expression, chewing, talking, and swallowing are often, but not always, involved.