ALS (Amyotrophic Lateral Sclerosis) is a devastating condition where the nerves which control the skeletal muscles (hands, feet, arms, legs, etc.) die off. Commonly known as Lou Gehrig's disease, it is a progressive neurodegenerative disease that attacks motor neurons in the brain (upper motor neurons) and spinal cord (lower motor neurons) and affects muscle function.
The motor neurons control the movement of various voluntary muscles including the diaphragm. Associated with the loss of the ability of motor neurons to function in ALS, the various muscles cells waste away (atrophy), resulting in increased muscle weakness. Ultimately, accumulated loss of motor neurons makes it impossible for voluntary control of normal muscle function. After sufficient loss of neurons to the diaphragm muscle, the person loses the ability to draw breath and eventually requires mechanical ventilation to sustain life.
Symptoms of ALS can include twitching and cramping of muscles (called fasciculation), stiffness in muscles (spasticity), increasing loss of motor control in hands and arms and legs, weakness and fatigue, slurred or thick speech and difficulty breathing or swallowing.
In most cases, ALS patients do not typically experience significantly impaired sensory neural functioning, intellectual reasoning, vision or hearing. This leaves a person with an active mind trapped in an inert body.
[Information courtesy of ALS Therapy Development Institute]