Amyotrophic lateral sclerosis (ALS) – commonly known as Lou Gehrig's disease – is a motor neuron disease. It's caused when the motor neurons that send electric "messages" from the brain to the spinal cord (upper motor neurons) or from the spinal cord (lower motor neurons) to the muscles are slowly being destroyed. These neurons are responsible for muscle movement.
When the messages don't get through from the spinal cord, the muscles eventually lose strength and waste away. This process is called atrophy or amyotrophy. When signals from the brain to the spinal cord are blocked, the muscles become stiff and slow. This is called spasticity.
Approximately 1 out of 100,000 people each year are newly diagnosed with ALS. It's more common in men than women, with symptoms usually appearing between the ages of 50 and 75. About 10% of people with ALS have a family history of the disease. The average life expectancy is 2 to 5 years after diagnosis.
The causes of ALS are starting to be understood. Multiple factors are at play, both genetic and environmental. At least 16 different genes are involved in ALS. No single environmental factor has been proven to cause it. ALS dose not appear to result from exposure to heavy metal or viral infection alone. Even blocking the neurotransmitter glutamate does not stop the disease.Genetic counselling and then possible genetic testing should be offered to all people diagnosed with ALS.
Symptoms and Complications
The symptoms of ALS are caused by the destruction of motor neurons resulting in gradual deterioration of the muscles. Muscle atrophy often starts in the hands or feet and moves its way up the arms to the shoulders or up the legs to the hips.
The early symptoms of ALS include muscle weakness, clumsy hand movements, muscle stiffness, and difficulty performing tasks that require delicate movements of the fingers or hands. Muscular weakness in the legs may cause tripping and falling. As the muscles lose strength, some people experience muscle cramps, twitches, or spasms. When ALS progresses, more muscle groups become affected, leading to:
- impaired speech
- difficulty swallowing
- breathing problems caused by a weakened diaphragm
In most patients, only motor neurons – and therefore only muscles – are affected with ALS. Eye muscles, as well as bladder and bowel muscles, aren't usually involved, and the disease doesn't affect a person's mind or any of the 5 senses. People remain alert, but often lose the ability to take care of themselves. It can even become impossible to breathe without the help of a respirator. In about 30% to 50% of patients, other parts of the brain are affected, which can lead to progressive cognitive decline, emotional instability, and even dementia.
There are several variants of ALS. Each has different symptoms and a different outcome.
Primary bulbar palsy: The initial or predominant symptoms are impaired speech or swallowing along with wasting of the tongue. The outcome is generally worse in this condition since swallowing and breathing are affected early in the course of the disease.
Progressive muscle atrophy: Muscle weakness and wasting are the principal features. Speech and swallowing are not affected and there is no spasticity. These individuals tend to have a slower course.
Primary lateral sclerosis: The main feature is spasticity with no muscle atrophy. The outcome is usually somewhat better.
Making the Diagnosis
When the muscles get progressively weaker, especially if a person's sensations aren't at all impaired, doctors will suspect ALS. The standard criteria for establishing the diagnosis of ALS are:
- the presence of lower and upper motor neuron degeneration with documented progression of symptoms, either within the same body area or to other areas
- the absence of electrodiagnostic (EMG) or pathologic (biopsy) evidence of another disease processes that could cause lower and/or upper motor neuron degeneration
- the absence of neuroimaging (MRI) evidence of other disease processes that could explain the symptoms
A series of tests may be needed to rule out other potential causes for symptoms. Electromyography (EMG) is used to determine whether the problem is in the muscle or the nerve cells. This test works by measuring the electrical activity in the muscle.
A magnetic resonance imaging (MRI) scan of the head or spine may be used to exclude other conditions that can damage or compress nerve cells such as cervical spondylosis, multiple sclerosis, and thyroid diorders.Based on where in the body symptoms first appeared, and where or how they progress over time, your doctor can tell the difference between ALS and other conditions.
Treatment and Prevention
Because the exact causes of the disease haven't been pinpointed, ALS cannot be prevented or cured. The treatment is focused on managing the symptoms and allowing the patient to have a good quality of life. Many health care specialists will be involved, including the family doctor, home nurses, a neurologist, respiratory therapist, physical therapists, occupational therapists, nutritionists, and social worders.
Medications are available, however, that may slow the progress of the disease and that deal with some of the symptoms.
Riluzole* is a medication that appears to prolong the life of some people with ALS by at least a few months. Riluzole seems to do two things: block sodium and calcium channels and increase the clearance of glutamate.
Muscle spasms – and sometimes cramps – can be controlled with the medications baclofen or diazepam. Medications can also be used to lower the amount of saliva that's made to help people who've lost the ability to swallow it.
To avoid choking or inhaling food and saliva into the lungs, a feeding tube might need to be placed into the stomach. People with difficulty breathing will eventually have to go on a respirator. Physical therapy can help people maintain strength in their muscles and control muscle contractions. Speech therapy can help people with speech and swallowing difficulties. Many will benefit from a motorized wheelchair and devices that allow communication through eye movements.
Although a person's physical state worsens, their mental capacity does not. To cope with the progression of the disease, good emotional support from family and friends is important. Support groups can also be helpful: the ALS Society of Canada can be contacted by phone (1-800-267-4257) or email (firstname.lastname@example.org), or accessed online at www.als.ca.End-of-life care is an essential component of the care for someone with ALS. The person should choose how they wish to be treated in the late phase of the disease. This is usually done by filling advance directives.
*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.
All material copyright MediResource Inc. 1996 – 2019. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/condition/getcondition/Amyotrophic-Lateral-Sclerosis