Etiology is a doctor's word for the cause--or causes--of a disease. Some of the most dreaded are of unknown etiology, because the less known about the cause of an illness, the less likely that there is a cure for it, or some way to prevent it or avoid getting it.
Amyotrophic lateral sclerosis is that kind of disease, a devastating, disabling, eventually fatal ailment affecting the motor nerve cells that control the muscles, and for which, so far, no cure has been found. Not only are we in the dark about why it strikes, but we don't know whom, where and when it may strike.
What we do know is that ALS (as it's often called) generally affects the nerves leading from the brain to the spinal cord and from the spinal cord and brain stem to the muscles, resulting in a progressive weakening and wasting of those muscles that have lost their nerve supply, as well as taut muscles and exaggerated muscular reflexes.
The name of the disease comes from A--lack of, Myo--muscle, Trophic--nourishment, Sclerosis-- hardening of areas in the Lateral--side (as well as the forward) portions of the spinal cord.
In time these progressive ravages, in the most common form, cause near or complete helpessness. The patient becomes a prisoner of his or her own body. At the same time the five senses (touch, taste, sight, smell, hearing) remain intact and the intellect is commonly unimpaired. As a victim commented, "It's a like being given a ringside seat at one's own dissolution."
Ordinarily ALS does not directly affect the bladder, bowel or sexual function. Some patients may have a noticeable lack of control over emotions. The patient, even though conscious of behaving oddly, may cry easily or laugh loudly in situations where others normally exert more control.
ALS is sometimes referred to as "Lou Gehrig's disease." It was this ailment that cut short the career and the life, in 1941 at age 35, of the great major league baseball slugger whose batting record and years of performance (2,130 consecutive games played) won him the nickname, "The Iron Man." Other celebrities who have fallen to the disease include former heavyweight champion prizefighter Ezzard Charles and actor David Niven. A current ALS patient is former Senator Jacob Javits of New York.
ALS is relatively uncommon. Although estimates vary as to the number of ALS cases diagnosed each year, the recorded deaths from this disease are a good indicator of occurrence because of its incurability. The National Center for Health Statistics reports that 2,305 persons died of ALS in this country in 1978 and 2,635 in 1979, a rate of slightly more than 1 per 100,000 of population. It's estimated that at any given time there are five to seven living victims of ALS per 100,000 people.
Most ALS victims are 40 to 70 years old, although some are veryt rarely as young as 20 or as old as 80. ALS claims about two times more men, than women. Race or nationality does not matter in who gets ALS, although the highest incidence worldwide has been among natives of the Mariana Islands in the western Pacific. About 5 to 10 percent of the cases occur in families where there already has been a victim. There is no basis, however, for predicting that any person in such a family is likely to get ALS.
Impaired speaking, swallowing (and subsequent choking from saliva accmulation) and cough reflexes, difficulty in breathing, and progressive weakness all result from degeneration of the nerve cells, or motor neurons, from the spinal cord to the muscles--the so-called lower motor neurons. Spasticity, or stiffness of the muscles, results from degeneration of the nerve cells that travel from the brain to the spinal cord--the upper motor neurons. ALS symptoms are a consequence of this as yet unexplained destruction of these two neuron systems, and can eventually result in total paralysis. About 50 percent of patients die within three years, and only 10 percent survive beyond 10 years. Generally the disease seems to progress steadily at a rapid or slow rate, and sometimes it seems to reach a plateau or standstill for varying periods, according to the Amyotrophic Lateral Sclerosis Society of America. The society reports that for some patients there appears to be a remission when the disease reaches a plateau, and some report improvements in varying degrees. No cause has been found for such variations.
In a paper on current research, the society says that patients don't die directly from ALS but from such secondary complications as malnutrition or choking caused by inability to swallow, pneumonia, or others, often equally treatable. The soceiety notes that various respiratory aids can be used to help a patient to breathe; nutrition can be maintained by the use of various devices, some requiring surgery, and the use of foods that are softer and more nutritious. There are drugs to treat or control excess salivation, spasticity, cramps, and other problems. The steady improvement in effective treatment of some symptoms and complications seems to be extending the period of patient survival, the society reports, although no treatment has been found to alter the natural progression of the disease.
Communication is a critical element in therapy for an ALS patient who has become unable to speak. Since the disease does not noticeably affect the eye muscles, communication devices that use codes based on eye movements have been developed for transmitting messages between patient and medical people or family. There are others, including small computers with artificial speech articulation, available for patients who can use their hands.
There are three major signals that can warn of the possible onset of ALS. In about a third of casaes the hands become clumsy; the person may drop objects or have trouble doing tasks that require fine coordination or manipulation of the hands and fingers, such as sewing or working with tools. Another third experience weakness or cramps in the legs, or involuntary jerks of the limbs. The patient may stumble or trip because of a slight foot drop. A third main sign is slowed speech or difficulty in swallowing, symptoms indicating involvement of nerves that emanate from a part of the brain steam. Weakness in speech can include slurring, thick speech, a monotonous tone, hoarseness, or reduced volumes. Other difficulties are encountered in swallowing, shifting food in the mouth, and controlling saliva.
A person may have ALS for a long time before symptoms are noted or pronounced enough to seek medical help. Some doctors believe the disease may exist without being diagnosed for up to 10 years. This may be because nerve cells that are still functioning take over much of the work of those lost as the disease progresses. A tendency to tire easily may be an early symptom. There may also be stiffness and spasticity or involuntary jerking of the limbs.
Although generally the disease begins with effects on muscles more distant from the brain and spine, as in the limbs, its progressions eventually results in complete paralysis. The muscles that control eye movements are affected very late in the course of the disease, if at all.
A suspected ALS victim is usually examined by a neurologist, who may set up a series of tests, no single test normally being adequate to confirm the disease. An electromyogram (EMG), in which needles are inserted into muscles to record their electrical activity, may be ordered. Other diseases, which may mimic ALS and which are treatable, may be identified by various studies. There may be X-ray checks for spinal column troubles. Or a myelogram may be done--injection of a dye into the spinal fluid to look for treatable problems of the spine that may affect the nerves.
For the spunky patient who wants to fight, there are many ways medical staffs and family can help, the society says. In the past patients died unnecessarily from respiratory complications, but today many of these can be alleviated with portable respirators that help the patient to breathe. Adequate nutrition is possible by feeding the patient soft food through a tube, either by mouth or a surgical opening. For patients with muscular atrophy, good nutrition is essential because it keeps the body from burning up as fuel whatever muscle tissue remains.
Much can be done to help the patient endure ALS. The patient should continue normal daily activities as long as possible, but avoid fatigue. It's quite often left up to the patient to decide how and when to use his or her strength. Simple exercises within the patient's capabilities can be done, with or without family assistance. Devices that enable a patient to continue daily activities include braces to prevent foot drop, band splints and limb supports, wheelchairs, and lift devices.
Bedridden patients need skin care and massages, and should be shifted frequently to help prevent bedsores. Devices such as wheelchair cushions, sheepskins, and water mattresses also are helpful. A patient whose movements are limited will need help with bowel and bladder functions. The ALS Society recommends drinking 10 glasses of waster or other liquids daily, to assure adequate urinary elimination, if the patient does not have too much difficulty swallowing this amount. Medicines or stool softeners should be used, upon the advice of a physician. Elastic support hose and elevation of the legs may be needed to prevent swelling and to prevent possible formation of blood clots.
Methods of control the normal production of saliva when problems arise from difficulty in swallowing include suction devices, drugs to thicken saliva, or surgery to reduce the flow. Some patients are able to use a handkerchief to control drooling. Besides blow bottles and respirators, simple deep breathing exercises are used to enable the patient to maintain maximum lung capacity. Doctors can advise family members how to help a patient cope with coughing difficulties. The patient should not be exposed to persons with respiratory tract infections such as cold and flu.
There are several motor neuron diseases. Some are variants of classical ALS; these include spinal muscular atrophy, progressive bulbar palsy, primary lateral sclerosis, and benign focal amyotrophy. There are also two genetically determined childhood motor neuron diseases: infantile spinal muscular atrophy (appearing while the child is in the womb or during the first few months after birth) and juventile spinal muscular atrophy, appearing at the age of 5 to 15, sometimes with multiple cases in one family.
Research into possible causes of ALS has looked into viruses and various toxic, immunological and metabolic factors, including possible environmental factors that may be common to all patients. Dr. Myron I. Varon, vice president and scientific director of the ALS Society, says he believes five areas will be important in solving the mystery of ALS:
* the identification, if it exists, of a protein that is needed to maintain the integrity of the motor neuron, and without which the neuron will die and the muscule atrophy;
* the nerve transport mechanism;
* relationship between male hormones (androgens) and motor neurons in males; * drastic reduction (in the motor neurons of ALS patients) of ribonucleic acid (RNA), which helps manufacture vital proteins in the cell; and
* metabolic studies at the neuromuscular junctions, where the nerve meets the muscle.
Dr. Varon feels that if ALS is caused by failure of the skeletal muscle to produce nerve growth hormone; it may be possible to supply this hormone to patients as insulin is supplied to diabetics. "What we are hoping for, of course," he says, "is the discovery of the insulin for ALS. ALS is not an active virus infection, an autoimmune disease, or a peculiar toxic reaction. I believe it is a metabolic abnormality . . . ."