Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease" or “Motor Neuron Disease,” is a progressive, neurodegenerative disease that affects "motor neurons", the cells that initiate and control the movement of muscles and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. Diseases of motor neurons are characterized as "upper" if they originate in the brain, and "lower" if they originate in the spinal cord. ALS affects both upper and lower motor neurons, while each person with ALS has varying amounts of upper and lower motor neuron disease and thus, varying symptoms.
Because the nerve cells that stimulate them have died, the muscle tissues waste away. Limbs begin to look "thinner" as muscle tissue atrophies. This results in progressive muscle weakness, atrophy, and often spasticity, or excess muscle tone. Only the motor neurons are affected. Other nerve cells, such as sensory neurons that bring information from sense organs to the brain, remain healthy.Symptoms of ALS:
At the onset of ALS the symptoms may be so slight that they are frequently overlooked. With regard to the appearance of symptoms and the progression of the illness, the course of the disease may include the following:
The initial symptoms of ALS can be quite varied in different people. The rate at which ALS progresses can be quite variable from one person to another. Not all individuals with ALS experience the same symptoms or the same sequences or patterns of progression. However, progressive muscle weakness and paralysis are universally experienced.
Based on U.S. population studies, a little over 5,600 people in the U.S. are diagnosed with ALS each year. (That's 15 new cases a day.) It is estimated that as many as 30,000 Americans have the disease at any given time. According to the ALS CARE Database, 60% of the people with ALS in the Database are men and 93% of patients in the Database are Caucasian.
Most people who develop ALS are between the ages of 40 and 70, with an average age of 55 at the time of diagnosis. However, cases of the disease do occur in persons in their twenties and thirties. Generally though, ALS occurs in greater percentages as men and women grow older. ALS is 20% more common in men than in women. However with increasing age, the incidence of ALS is more equal between men and women.
There are several research studies – past and present – investigating possible risk factors that may be associated with ALS. More work is needed to conclusively determine what genetics and/or environment factors contribute to developing ALS.
Half of all people affected with ALS live at least three or more years after diagnosis. Twenty percent live five years or more; up to ten percent will live more than ten years.
Although the cause of ALS is not completely understood, the recent years have brought a wealth of new scientific understanding regarding the physiology of this disease. However it is likely that ALS is a complex multi-system disease with several mechanisms that cause the death of motor neurons. Any one of these mechanisms or a combination of several may be responsible for the disease. Furthermore there are likely to be genes and hereditary factors that will modify the disease and susceptibility.
Possible Causes of ALS
ALS is a very difficult disease to diagnose. To date, there is no one test or procedure to ultimately establish the diagnosis of ALS. It is through a clinical examination and series of diagnostic tests, often ruling out other diseases that mimic ALS, that a diagnosis can be established. A comprehensive diagnostic workup includes most, if not all, of the following procedures:
These tests are done at the discretion of the physician, usually based on the results of other diagnostic tests and the physical examination. There are several diseases that have some of the same symptoms as ALS and most of these conditions are treatable.
While there is not a cure or treatment today that halts or reverses ALS, there is one FDA approved drug, riluzole, that modestly slows the progression of ALS. As well, there are several other drugs in clinical trials that hold promise.
More importantly, there are significant devices and therapies that can manage the symptoms of ALS that help people maintain as much independence as possible and prolong survival.
The quality of life of patients with ALS can often be improved by various treatments and interventions. Proper positioning, exercise, physiotherapy, and medications can help keep patients comfortable. Patients with significant bulbar involvement may require help to improve communication or ensure safe and adequate nutrition. A gastrostomy (feeding) tube may be suggested if there is recurrent pneumonia, high risk of aspiration (inhaling food or liquids into the lungs), inadequate nutrition, rapid weight loss, or extended feeding time. A wide range of devices and techniques can address problems with communication. Ultimately, ALS may result in respiratory decline, requiring consideration of respiratory support, including non-invasive ventilation such as a BiPAP (bilevel positive airway pressure), or a tracheostomy and a ventilator.