Amyotrophic Lateral Sclerosis (ALS) is a fast progressing, degenerative, neurological disease. The disease is marked by weakness, atrophy and paralysis of the body’s voluntary muscles as a result of motor neuron degeneration and death (Wijesekera & Leigh, 2009). ALS gets its name from Greek origin: Amyotrophic- “A” meaning without, “myo” meaning muscle, “trophic” meaning nourishment, literally translated this term means “without muscle nourishment”. “Lateral Sclerosis” refers to the hardening and scarring of the anterior and lateral corticospinal tracts as the disease progresses (Wijesekera & Leigh, 2009). In the US, ALS is commonly referred to as “Lou Gehrig’s Disease” for the famous Yankees first baseman, who died from the disease in 1941. In the UK, ALS is known as “Motor Neuron Disease” (MND) and in France it is known as “Charcot’s Disease”, for the French doctor Jean-Marie Charcot who first wrote about the disease in 1869. (NINDS, 2003; MFMER 2010). ALS occurs in 1-3 people per 100,000 worldwide. The onset of ALS generally occurs in people between 40 and 60 years of age, however it can develop at any age (NINDS, 2003). The disease shows a slight preference for men. However, in diagnoses after the age of seventy, the preference disappears. There are two forms of ALS: “In 5% to 10% of people with ALS, the disease is inherited as an autosomal dominant trait and is referred to as familial amyotrophic lateral sclerosis. In 90% to 95% of people with ALS, there is no family history of the disease, and these people are said to have sporadic amyotrophic lateral sclerosis.” (Bello-Haas, Kloos & Mitsumoto, 1998, p. 1313). The two forms of ALS will be discussed further in the Etiology section of this paper.
ALS is incurable and fatal. The majority of people with ALS die within 3-5 years of their diagnosis, usually due to respiratory failure. Treatments are generally focused on relieving symptoms enough to improve a patient’s quality of life (NINDS, 2003). Pathophysiology
Motor neurons (upper and lower) are located within the Central Nervous System and control all of the voluntary muscles of the body. They also control partially involuntary functions such as respiration. ALS is characterized by progressive loss of the upper and lower motor neurons. The death of the motor neuron cell body is followed by axonal degeneration and subsequent denervation of corresponding muscles. Loss of upper motor neurons will lead to the spasticity and hyper-reflexivity typically seen with ALS. Loss of the lower motor neurons is the cause of muscle weakness, atrophy and paralysis. The disease process, with regards to muscles affected, takes one of three forms: Spinal onset, Bulbar onset (muscles of the face, neck, jaw and throat) or Respiratory onset (Wijesekera & Leigh, 2009). Regardless of the onset, all of these muscles will be affected. The onset of ALS is similar to dropping a pebble in a lake; the location that you drop the pebble doesn’t change the fact that the waves created will eventually travel through the entire body of water. The majority of cases are spinal onset (about 70%). With spinal onset, the symptoms of muscle twitching and/or weakness can start in either the upper or lower extremities; the other limbs will develop similar weakness and eventual atrophy and paralysis. In the later stages of progression, flexor spasms and contractures may develop. With spinal onset bulbar and respiratory weakness and paralysis will eventually develop. Death from ALS is a result of either respiratory failure or aspiration/asphyxiation (due to respiratory and bulbar muscle paralysis). (Bello-Haas, Kloos & Mitsumoto, 1998; NINDS, 2003; MFMER 2010)
Although there are several theories that exist, the exact cause of ALS is unknown. Researchers have formed theories based on the physiological changes that take place in patients with ALS and the discovery that the Familial form of the disease is...
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