Tuesday, October 20, 2009


Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a rapidly progressive, invariably fatal neurological disease. This disease attacks the nerve cells (neurons) responsible for controlling voluntary muscles. ALS belongs to a group of disorders known as motor neuron diseases, which are characterized by the gradual degeneration and death of motor neurons.

If a person has amyotrophic lateral sclerosis (ALS) and one or more immediate family members also has the disease (for example, a parent, sibling, or grandparent), then the condition is considered familial amyotrophic lateral sclerosis.

Motor neurons are nerve cells located in the brain, brainstem, and spinal cord. These nerve cells serve as controlling units and provide vital communication links between the nervous system and the voluntary muscles of the body. Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord (called lower motor neurons). From here, they are transmitted to particular muscles.
Because amyotrophic lateral sclerosis affects only motor neurons, the disease does not impair a person's:
  • Mind
  • Personality
  • Intelligence
  • Memory.
Nor does it affect a person's ability to:
  • See
  • Smell
  • Taste
  • Hear
  • Recognize touch.
People with this condition usually maintain control of eye muscles and bladder and bowel functions.

ALS Symptoms

The early symptoms of ALS (amyotrophic lateral sclerosis) are frequently overlooked because the disease is so subtle in its early stages. When present, the earliest ALS symptoms may include:
  • Muscle stiffness, twitching, or cramping
  • Weakness affecting an arm or leg
  • Slurred and nasal-sounding speech
  • Difficulty chewing or swallowing.
These general symptoms then develop into more obvious weakness or atrophy (loss of muscle tissue) that may cause a doctor to suspect ALS.
The body parts that early ALS affects will depend on which muscles are damaged first. In some cases, one of the legs is affected and the person experiences awkwardness when walking or running -- or he or she begins to trip or stumble more often. In other cases, the person experiences problems with a hand or arm and has difficulty with simple tasks requiring manual dexterity, such as buttoning a shirt, writing, or turning a key in a lock. Other people may experience speech problems as their first symptom of ALS.

Regardless of where the ALS symptoms first appear, muscle weakness and atrophy will spread to other parts of the body as the disease progresses.
Eventually, people who have ALS will experience increased problems with:
  • Moving
  • Swallowing (dysphagia)
  • Speaking or forming words (dysarthria).

Those with ALS symptoms are aware of their progressive loss of function because this disease generally does not affect a person's thinking or mental capacities. Therefore, people with this condition may experienceanxiety and/or depression. Also, a small percentage of people may experience problems with their memory or decision-making abilities, and there is growing evidence that some people may develop a form ofdementia.
In the later stages of ALS, the person will experience the following symptoms:
  • Difficulty breathing as the muscles of the respiratory system weaken
  • Loss of the ability to breathe on his or her own (must depend on ventilator support for survival)
  • An increased risk of pneumonia.
It's important for people with ALS (and their loved ones) to talk to their healthcare provider about the course of the disease and the options fortreatment of ALS. This can help the patient make informed decisions in advance.

Causes of ALS

The cause or causes of ALS (amyotrophic lateral sclerosis) are not known, and scientists do not yet know why ALS strikes some people and not others.
ALS research scientists are looking at a number of possible ALS causes, including:
  • Genetics
  • Glutamate
  • Autoimmune responses
  • Environment.

Gene Mutations

An important step toward finding the causes of ALS came in 1993, when research scientists discovered that mutations in the gene that produces the superoxide dismutase 1 (SOD1) enzyme were associated with some cases of familial ALS.

The SOD1 enzyme is a powerful antioxidant that protects the body from damage caused by free radicals. Free radicals are highly reactive molecules that are produced by cells during normal metabolism. If these free radicals are not neutralized, they can accumulate and cause random damage to the DNA and proteins within cells.
Although it is not yet clear how the SOD1 gene mutation leads to motor neuron degeneration, researchers have theorized that an accumulation of free radicals may result from the faulty functioning of this gene. In support of this theory, animal studies have shown that motor neuron degeneration and deficits in motor function accompany the presence of the SOD1 mutation.


Studies have also focused on the role of glutamate in motor neuron degeneration. Glutamate is one of the chemical messengers or neurotransmitters in the brain.
Scientists have found that, compared to healthy people, ALS patients have higher levels of glutamate in the serum and spinal fluid. Laboratory studies have demonstrated that neurons begin to die off when they are exposed over long periods to excessive amounts of glutamate.

Autoimmune Responses

Autoimmune responses -- which occur when the body's immune system attacks normal cells -- have been suggested as one possible cause for ALS. Some scientists theorize that antibodies may directly or indirectly impair the function of motor neurons, interfering with the transmission of signals between the brain and muscles.

Environmental Factors

In searching for possible ALS causes, researchers have also studied environmental factors, such as exposure to toxic or infectious agents, and examined the possible role of dietary deficiency or trauma. However, as of yet, there is insufficient evidence to implicate these factors as possible ALS causes.

ALS Diagnosis

There is no single test used to make an ALS diagnosis. An ALS diagnosis is typically based on a person's symptoms, such as spasticity and muscle weakness. Tests used to rule out other diseases before making an accurate ALS diagnosis include magnetic resonance imaging and electromyography. In order for your doctor to make a definitive ALS diagnosis, he or she will also need your full medical history and will conduct a neurological exam.

Treatment of ALS

Scientists have not found a cure for ALS (amyotrophic lateral sclerosis). However, the U. S. Food and Drug Administration (FDA) has approved the first drug treatment for ALS, which is called riluzole.
Riluzole is believed to:
  • Reduce damage to motor neurons by decreasing the release of glutamate
  • Prolong survival by several months (mainly in those with difficulty swallowing)
  • Extend the time before a patient needs ventilation support.
Riluzole does not reverse the damage that has already occurred to the motor neurons, and patients taking riluzole must be monitored for liver damage and other possible side effects.

Team Effort for Treatment of ALS

Other treatments of ALS are designed to relieve ALS symptoms and improve the quality of life for patients. Multidisciplinary teams of healthcare professionals are available to provide supportive care, including:
  • Physicians
  • Pharmacists
  • Physical, occupational, and speech therapists
  • Nutritionists
  • Social workers
  • Home care and hospice nurses.
These teams can design an individualized ALS treatment plan of medical and physical therapy, and provide special equipment aimed at keeping patients as mobile and comfortable as possible.

ALS Research

Scientists studying ALS are hoping to discover what causes it and to develop more effective treatment methods, among other things. To that end, ALS research scientists are trying to better understand apoptosis (programmed cell death) and examining the disease in families. Investigators are optimistic that research studies will eventually lead to better treatments for ALS.

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