What is amyotrophic lateral sclerosis (ALS)?
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a neuromuscular disorder that causes progressive paralysis and ends in death. ALS is a motor neuron disease, first described in 1869 by the noted French neurologist Jean-Martin Charcot. Although the cause of ALS is not completely understood, ALS causes a degeneration of the motor neurons in the brain and spinal cord. When these cells die, it is impossible for the brain to signal voluntary muscle control. People with ALS may experience muscle weakness and impaired speaking, swallowing and breathing; and eventually total paralysis and death.
ALS is a progressive, degenerative disease of the nervous system. It is one of a group of diseases, called motor neuron diseases (MND), in which specialized nerve cells that control movement of the voluntary muscles gradually cease functioning and die. These nerve cells, called motor neurons, carry impulses from the brain to the brainstem and the spinal cord. The impulses are then carried to the muscles. The muscles respond to these messages by coordinated relaxation or contraction corresponding to willed movement. In ALS and other motor neuron diseases, motor neurons gradually deteriorate. Because the nerve cells that stimulate them have died, the muscle tissues waste away. 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.
ALS attacks only 'motor' neurons. Sight, touch, hearing, taste, smell and muscles of the eyes and bladder are
generally not affected. Sexual function and drive are not affected. The mind is not affected, and remains sharp despite the progressive degenerating condition
of the body.
What does "Amyotrophic Lateral Sclerosis" mean?
"A-myo-trophic" comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment---"No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that nourish the muscles are located. As this area degenerates it leads to scarring or hardening--"sclerosis"--in the region.
Are there other names for ALS?
ALS, also known as motor neuron disease (MND), is commonly called Lou Gehrig's disease for the famous New York Yankee's baseball player who died of ALS in 1941. ALS is sometimes referred to as Charcot's disease for the French neurologist Jean-Martin Charcot who identified the disease in 1869.
Who gets ALS?
Most who develop ALS are between 40 and 70 years of age, although the disease can strike at any age. Men are affected slightly more frequently than women. ALS occurs throughout the world regardless of racial, ethnic or socioeconomic status.
Some studies have identified areas that at certain times have appeared to have greater than expected numbers of cases. This has occurred in the past in the western Pacific islands and in parts of Japan and Australia. Other areas in the continental United States have been reported but have not stood up to careful epidemiological investigations.
How common is ALS?
More than 5,600 Americans are diagnosed with ALS each year or two new ALS cases per 100,000 people (incidence). Approximately 35,000 people at any given time are living with ALS in the United States or six to eight people per 100,000 population (prevalence). The incidence of ALS is close to that of multiple sclerosis and four times that of muscular dystrophy.
What are the symptoms of ALS?
ALS strikes people in different ways and progression of the disease is often irregular. The groups of muscles affected and the order in which they are affected varies from one person to another. Early symptoms usually include tripping, dropping things, abnormal fatigue of the arms and/or legs, changes in speaking or slurred speech, difficulty swallowing, muscle cramps, spasms, and twitches and uncontrollable periods of laughing or crying. The hands and feet may be affected first, causing weakness or difficulty in coordination in one limb, difficulty in walking or using the hands for the activities of daily living such as dressing, washing and buttoning clothes.
About 25% of patients have bulbar (throat) onset, which means that voice and swallowing are first affected. About 50% have arm onset, and 25% leg onset.
The disease frequently takes its toll before being positively diagnosed: many patients are significantly debilitated before learning that they have ALS.
Muscle wasting gradually spreads to the muscles of the trunk of the body, and the disease eventually affects swallowing, chewing and breathing. Complete paralysis eventually results, usually occurring within two to five years of diagnosis.
When the diaphragm is attacked, the patient is unable to breathe for him/herself, and faces permanent ventilator support in order to survive.
ALS attacks only 'motor' neurons. Sight, touch, hearing, taste, smell and muscles of the eyes and bladder are generally not affected. Sexual function and drive are not affected. The mind is not affected, and remains sharp despite the progressive degenerating condition of the body.
The symptoms and clinical features of the disease depend on the location of the affected motor neurons. Speech and swallowing impairments are called bulbar symptoms. They indicate that neurons in the brainstem are affected. Weakness of the respiratory muscles, muscle weakness, and loss of mobility in the arms and legs are called somatic symptoms. They indicate spinal cord involvement. In classical ALS, a mixture of upper and lower motor neurons are involved, with both bulbar and somatic symptoms.
• Lower motor neuron symptoms
Weakness and muscle wasting are common when lower motor neuron involvement predominates. The patient or physician usually notices fasciculation, or muscle twitching. Fasciculation is a sign of muscle irritability, as the normal action of the lower motor neuron on the muscle is impaired. The sole involvement of lower motor neurons can be seen in a form of ALS called progressive muscular atrophy. Fasciculation is described as "benign" if there is no muscle weakness, atrophy, or impairment of motor function. Fasciculation is described as "pathologic" when it occurs in ALS with other symptoms.
• Upper motor neuron symptoms
Spasticity, or stiffness, in the lower limbs, face, or jaw indicates upper motor neuron involvement. Spasticity in
the legs often produces severe walking difficulties. The patient may complain of heaviness, fatigue, stiffness, or lack of coordination of any affected limb. Reflexes are very brisk, or exaggerated. Outbursts of laughter or crying with minimal provocation can occur. This is called emotional lability and is referred to as a pseudo-bulbar affect. Both brisk reflexes and emotional lability involve the inability to inhibit reflexes.
How is ALS diagnosed?
The diagnosis of ALS is a "clinical diagnosis," meaning there is no specific test that gives a definitive answer. Before a diagnosis of ALS is confirmed, many tests must be administered to rule out illnesses with symptoms that may mimic ALS. These may include an MRI of the brain or spinal cord, an electromyography (EMG) study of nerve and muscle function and a variety of blood and urine tests. By evaluating these tests, the patient's medical history and performing a complete neurological exam, the neurologist can usually reach a definitive diagnosis.
It is always recommended that patients seek a second opinion by a neurologist experienced with ALS in order to decrease the possibility of an incorrect diagnosis. In some cases a definitive diagnosis can be made only after several months of observation and retesting.
Is there any treatment for ALS?
Many of the symptoms of ALS are treatable, but there are no drugs available to cure the disease. Rilutek©, the first FDA-approved medication for the treatment of ALS, has been shown to modestly increase lifespan. Since it became available in 1996, two retrospective studies presented at the 12th International Symposium on ALS/MND in 2001 indicated that Rilutek© appears to have a greater impact on life expectancy than was reported in initial drug trials.
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.