About ALS (Amyotrophic Lateral Sclerosis)
Amyotrophic Lateral Sclerosis — more commonly referred to as Lou Gehrig's disease or ALS — is a neuromuscular disease that causes damage to the nerve cells controlling voluntary muscle movement, also known as motor neurons. It belongs to a group of diseases, known as motor neuron diseases, which affect the motor system.
ALS is characterized by damage to the motor system. The motor system is a tag team of nerve cells (neurons) that carry messages from the area that controls movement in the brain to the muscle. The first nerve cell in the tag team carries the signal from the brain to the lower part of the brain (brainstem) and the spinal cord. It is referred to as the upper motor neuron (UMN) or corticospinal tract. The upper motor neuron contacts a second motor neuron referred to as the lower motor neuron (LMN) or anterior horn cell. The LMN then carries the signal to the muscle.
ALS (Amyotrophic Lateral Sclerosis) Facts
ALS usually affects people between 55 and 75 years of age, although all ages can be affected.
While it is usually not inherited, about 5-10% of cases of ALS are familial.
The prevalence rate (how many people have ALS at one time) is about 4 cases per 100,000 people.
The incidence rate (how many new cases of ALS occur in a time period) is about 1 new case per 100,000 people each year.
Males are more commonly affected by ALS, at a ratio of about 2:1.
ALS (Amyotrophic Lateral Sclerosis) Symptoms
ALS Symptoms vary from one person to the next. Symptoms reflect weakness and thinning of muscles due to the involvement of the LMN as well as stiffness from the UMN involvement. Onset can begin in the muscles that are innervated by the bulbar neurons (such as those used in speaking and swallowing) or in muscles innervated by nerve cells in the spinal cord causing weakness in one arm or one leg. A person newly diagnosed with ALS may:
Trip, drop things, slur his or her speech, twitch, and laugh or cry uncontrollably.
Experience abnormal fatigue of the arms or legs and muscle cramps.
Have difficulty walking and/or performing activities requiring the hands.
In 20% of ALS cases, voice and swallowing begin to decline first. Another 40% have symptoms in the arm first while the rest of people experience problems in their legs. Over time, the disease spreads from one area to another and gradually the people living with ALS will lose movement in muscles throughout the body, including the muscles used in breathing.
The average lifespan after diagnosis with ALS is about 36 months.
Diagnosis of ALS (Amyotrophic Lateral Sclerosis)
The diagnosis of ALS is made by identifying damage to the motor system, with damage to both the upper and lower motor neurons. This is done using a clinical examination and electomyography (an EMG test). All other possible causes of that damage must be excluded and there must be progression of the weakness over time with involvement of multiple areas in the nervous system. The areas that are evaluated include the bulbar region (speech and swallowing), cervical region (arms, diaphragm), thoracic region (muscles of breathing), and the lumbar region (legs).
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