Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. While this diseases is also known as Motor Neuron Disease (MND), it is better known in the United States as Lou Gehrig’s Disease—after the famous baseball player who was diagnosed with the disease in 1939.
Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.
As the disease progresses, weakness spreads to all parts of the body. Difficulty breathing can lead to the need for mechanical ventilation. Infection, especially pneumonia, is a common problem with end stage ALS. The median survival from the time of diagnosis is three to five years. About 10 percent of ALS patients can live 10 years or more. Survival beyond 20 years is rare. Significantly, in ALS, the muscles that control eye movement are generally the last to be affected. ALS patients who have lost control of most other muscles can spend many years being trapped in their own body. While they are alive and their brain is largely unaffected, they still cannot communicate even a simple instruction like, “I want water.” This condition, which can also happen as a result of other diseases and injuries, is referred to as “locked- in syndrome.”
A significant portion of the life of an ALS patient on a ventilator is in this state—the brain is functioning normally yet the patient is unable to communicate.