Overview of Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease, is a progressive neuromuscular disease that weakens and eventually destroys motor neurons (components of the nervous system that connect the brain with the skeletal muscles).
Upper motor neurons are located in the cerebral cortex of the brain and conduct impulses from the motor cortex to nerves in the brain or the spinal cord. Lower motor neurons are peripheral neurons that originate in the spinal cord and conduct impulses to the skeletal muscles. Skeletal muscles are involved with voluntary movements, such as walking and talking. The lower motor neurons transmit the command to move from the brain to the skeletal muscles, which respond by contracting.
A person with ALS usually presents with problems in dexterity or gait resulting from muscle weakness, or with difficulty speaking or swallowing. Sphincter control, sensory function, intellectual ability, and skin integrity are preserved. Patients become paralyzed and often require ventilation and surgery to provide a new opening in the stomach (gastrostomy). Loss of respiratory function is ultimately the cause of death.
Incidence and Prevalence of ALS
Approximately 30,000 patients in the United States currently have ALS. The disease has no racial, socioeconomic, or ethnic boundaries. The life expectancy of ALS patients usually ranges from about 3 to 5 years after diagnosis. ALS is most commonly diagnosed in middle age and affects men more often than women.