Amyotrophic lateral sclerosis (ALS):

A progressive disease of the central nervous system that disrupts the way the brain sends messages to certain muscles, including those used for breathing and swallowing. The disorder causes muscle weakness. As the disease progresses, ALS makes it difficult, and often impossible, to move these muscles. The cause is unknown, and there is no known cure.

Anesthesia:

drug-induced loss of sensation to avoid pain.

Asthenia:

physical weakness and loss of strength.

Atrophy:

the wasting away of tissues or organs in the body.

Biopsy:

an invasive medical test that removes tissue from the body to examine it under a microscope.

Central nervous system:

the body’s "communication network," made up of the brain and spinal cord.

Electromyography (EMG):

a medical test used to evaluate and diagnose disorders of the muscles and nerves. Electrodes are inserted into the muscle, or placed on the skin overlying a muscle or muscle group, and electrical activity and muscle response are recorded.

Invasive:

a procedure for diagnosis or treatment that involves surgery.

Lou Gehrig:

a famous New York Yankees first baseman from the 1930s who developed ALS. ALS is also referred to as “Lou Gehrig’s Disease.”

Magnetic resonance imaging (MRI):

A noninvasive procedure that produces a high-contrast, two-dimensional view of an internal organ or structure, typically of the brain and spinal cord.

Mechanical ventilator:

a machine that inflates and deflates the lungs to help with breathing.

Motor neurons:

nerve cells of the central nervous system that act as messengers between the brain and muscle tissue.

Muscle:

the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle that moves extremities and external areas of the body is called "skeletal muscle." The heart muscle is called "cardiac muscle." And muscle in the walls of arteries and the bowel is called "smooth muscle."

Muscle cramps:

involuntary, painful shortening of muscles.

Muscle weakness

loss of muscle strength with increased fatigue, loss of coordination, and difficulty with motor skills.

Neurologist:

a doctor who specializes in the diagnosis and treatment of disorders in the central, peripheral, and autonomic nervous system.

Physical examination:

a thorough assessment of a patient’s physical condition to collect information for diagnosis.

Placebo:

a pill without medicine in it, given to people in clinical trials as a “control.”

Trachea:

the windpipe that leads from the mouth to the lungs.

Tracheostomy:

a surgical operation where a plastic breathing tube is inserted through a hole created in a patient’s windpipe to allow access to a machine to help with breathing.