Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a progressive neurodegenerative disease that affects motor neurons in the brain and spinal cord. As the motor neurons die, it leads to the loss of ability to initiate and control muscle movement, resulting in increasing muscle weakness and eventual paralysis. While the cause is unknown, early symptoms often include weakness in the limbs, difficulty speaking, swallowing, or breathing. There is currently no cure and treatments can only modestly slow progression, but assistive devices and therapies can help maintain independence for as long as possible.