Causes and Symptoms
There are three kinds of muscle tissue in the human body: smooth muscle, cardiac muscle, and striated muscle. Smooth muscle tissue is found around the intestines, blood vessels, and bronchioles in the lung, among other areas. These muscles are controlled by the autonomic nervous system, which means that their movement is not subject to voluntary action. They have many functions: They maintain the airway in the lungs, regulate the tone of blood vessels, and move foods and other substances through the digestive tract. Cardiac muscle is found only in the heart. Striated muscles are those that move body parts. They are also called voluntary muscles because they must receive a conscious command from the brain in order to work. They supply the force for physical activity, and they also prevent movement and stabilize body parts.
Muscles are subject to many disorders: Muscle sprains, strains, and spasms are common events in everyone’s life and, for the most part, they are harmless, if painful, results of overexercise, accidents, falls, bumps, or countless other events. Yet these symptoms can also signal serious myopathies, or disorders within muscle tissue.
Myopathies constitute a wide range of diseases. They are classified as inflammatory myopathies or metabolic myopathies. Inflammatory myopathies include infections by bacteria, viruses, or other microorganisms, as well as other diseases that are possibly autoimmune in origin (that is, resulting from and directed against the body’s own tissues). In metabolic myopathies, there is some failure or disturbance in the body’s ability to maintain a proper metabolic balance or electrolyte distribution. These conditions include glycogen storage diseases, in which there are errors in glucose processing; disorders of fatty acid
metabolism, in which there are derangements in fatty acid oxidation; mitochondrial myopathies, in which there are biochemical and other abnormalities in the mitochondria of muscle cells; endocrine myopathies, in which an endocrine disorder underlies muscular symptoms; and the periodic paralyses, which can be the result of inherited or acquired illnesses. This is only a partial list of the myopathies, the symptoms of which include weakness and pain.
Muscular dystrophies are a group of inherited disorders in which muscle tissue fails to receive nourishment. The results are progressive muscular weakness and the degeneration and destruction of muscle fibers. The symptoms include weakness, loss of coordination, impaired gait, and impaired muscle extensibility. Over the years, muscle mass decreases and the arms, legs, and spine become deformed.
Neuromuscular disorders include a wide variety of conditions in which muscle function is impaired by faulty transmission of nerve impulses to muscle tissue. These conditions may be inherited; they may be attributable to toxins, such as in food poisoning (for example, botulism) or by pesticide poisoning; or they may be side effects of certain drugs. The most commonly seen neuromuscular disorder is
myasthenia gravis.
The muscular disorders most often seen are those that result from overexertion, exercise, athletics, accidents, and trauma. Injuries sustained during sports and games have become so significant that sports medicine has become a recognized medical subspecialty. Besides the muscles, the parts of the body involved in these disorders include tendons (tough, stringy tissue that attaches muscles to bones), ligaments (tissue that attaches bone to bone), synovia (membranes enclosing a joint or other bony structure), and cartilage (soft, resilient tissue between bones). A sprain is an injury in which ligaments are stretched or torn. In a strain, muscles or tendons are stretched or torn. A contusion is a bruise that occurs when the body is subjected to trauma; the skin is not broken, but the capillaries underneath are, causing discoloration. A spasm is a short, abnormal contraction in a muscle or group of muscles. A cramp is a prolonged, painful
contraction of one or more muscles.
Sprains can be caused by twisting the joint violently or by forcing it beyond its range of movement. The ligaments that connect the bones of the joint stretch or tear. Sprains occur most often in the knees, ankles, and arches of the feet. There is pain and swelling, and at least some immobilization of the joint.
A
strain is also called a pulled muscle. When too great a demand is placed on a muscle, it and the surrounding tendons can stretch and/or tear. The main symptom is pain; swelling and muscle spasm may also occur.
Muscle spasms and cramps are common. Sometimes they occur spontaneously, such as the calf muscle cramps that occur at night. Sometimes they are attributable to muscle strain (the charley horse that tightens thigh muscles in runners and other athletes). Muscles that are used often will go into spasm, such as those in the thumb and fingers of writers (writer’s cramp), as can muscles that have remained in one position for too long. Muscle spasms and cramps can also occur as direct consequences of dehydration; they are common in athletes who perspire excessively during hot weather.
Some injuries to muscles and joints occur so regularly that they are named for the activities associated with them. A good example is tennis elbow, a condition that results from repeated, vigorous movement of the arm, such as swinging a tennis racket, using a paintbrush, or pitching a baseball. Runners’ knee can afflict joggers and other athletes. It is usually caused by sprains in the knee ligaments; there is pain and there may be partial or total immobilization of the knee. Achilles tendinitis, as the name suggests, is inflammation of the Achilles tendon in the heel. It is usually the result of excessive physical activity that causes small tears in the tendon. Pain and immobility are symptoms. Tendinitis can occur in other joints as well; elbows and shoulders are common
sites. Tenosynovitis is inflammation of the synovial
membrane that sheathes the tendons in the hand. It may be caused by bacterial infection or may be attributable to overexertion.
Tumors and cancerous growths in muscle tissue are rare. If a lump appears in muscle, it is usually a lipoma, a fatty deposit that is benign. One tumor, called rhabdomyosarcoma, however, is malignant and can be fatal.
Treatment and Therapy
The myopathies are a wide group of diseases, and treatment varies considerably among them. The muscular dystrophies also vary in their treatment methods. Physical therapy is recommended to prevent contractures, the permanent, disfiguring muscular contractions that are a feature of the disease. Orthopedic appliances and surgery are also used. Because these diseases are genetic, it is sometimes recommended that people with a familial history of muscular dystrophy be tested for certain genetic markers that would suggest the possibility of disease in their children.
Myasthenia gravis is treated with drugs that increase the number of neurotransmitters available where nerves and muscles come together. The drugs help improve the transmission of information from the brain to the muscle tissue. In some cases, a procedure called plasmapheresis is used to eliminate blood-borne substances that may contribute to the disease. Surgical removal of the
thymus gland is helpful in alleviating symptoms in some patients.
In treating the many muscle disorders that are caused by athletic activity and excessive wear and tear on the muscle, the R-I-C-E formula is recommended. The acronym stands for rest-ice-compression-elevation: The patient must rest and not use or exercise the limb or muscle involved; an ice pack is applied to the injury; compression is supplied by wrapping a moist bandage snugly over the ice, reducing the flow of fluids to the injured area; and the injured limb is elevated. If there is a fracture involved, the limb must be properly splinted or otherwise immobilized before elevation. The ice pack is held in place for twenty minutes and removed, but the bandage is held in place. Ice therapy can be resumed every twenty minutes.
Heat is also part of the therapy for strains and sprains, but it is not applied until after the initial swelling has gone down, usually after forty-eight to seventy-two hours. Heat raises the metabolic rate in the affected tissue. This brings more blood to the area, carrying nutrients that are needed for tissue repair. Moist heat is preferred, and it can be supplied by an electrical heating pad, a chemical gel in a plastic bag, or hot baths and whirlpools. In using pads and chemical gels, there should be a layer of toweling or other material between the heat source and the body. The temperature for a whirlpool or hot bath should be about 106 degrees Fahrenheit. Only the injured part should be immersed, if possible. As in the ice treatments, heat should be applied for twenty minutes and can be repeated after twenty minutes of rest.
Analgesics are given for pain. Over-the-counter preparations such as aspirin, acetaminophen, or ibuprofen are used most often. Sometimes, when pain is severe, more potent medications are required. Steroids are sometimes prescribed to reduce inflammation, and nonsteroidal anti-inflammatory drugs (NSAIDs) can alleviate both pain and inflammation. If a strained muscle or tendon is seriously torn or otherwise damaged, surgery may be required. Similarly, if a sprain involves torn or detached ligaments, they may have to be surgically repaired.
Muscle spasms and cramps may require both manipulation and the application of heat or cold. The affected limb is gently extended to stretch the contracted muscle. Massage and immersion in a hot bath are useful, as are cold packs.
Tennis elbow, runners’ knee, and
tendinitis respond to R-I-C-E therapy. Ice is applied to the injured site, and the limb is elevated and allowed to rest. When tenosynovitis is caused by bacterial infection, prompt antibiotic therapy may be necessary to avoid permanent damage. When it is attributable to overexertion, analgesics may help relieve pain and inflammation. Rarely, a corticosteroid is used when other drugs fail.
Often, the injured site requires physical therapy for the full range of motion to be restored. The physical therapist analyzes the patient’s capability and develops a regimen to restore strength and mobility to the affected muscles and joints. Physical therapy may involve massage, hot baths, whirlpools, weight training, and/or isometric exercise. Orthotic devices may be required to help the injured area heal.
An important aspect of sports medicine and the treatment of sports-related muscle disorders is prevention. Many painful, debilitating, and immobilizing episodes can be avoided by proper training and conditioning, intelligent exercise practice, and restriction of exertion. Before undertaking any sport or strenuous physical activity, the individual is advised to warm up by gentle stretching, jogging, jumping, and other mild muscular activities. Arms can be rotated in front of the body, over the head, and in circles perpendicular to the ground. Knees can be lifted and pulled up to the chest. Shoulders should be gently rotated to relax upper-back muscles. Neck muscles are toned by gently and slowly moving the head from side to side and in circles. Back muscles are loosened by bending forward and continuing around in slow circles.
If a joint has been injured, it is important to protect it from further damage. Physicians and physical therapists often recommend that athletes tape, brace, or wrap susceptible joints, such as knees, ankles, elbows, or wrists. Sometimes a simple commercial elastic bandage, available in various configurations specific to parts of the body, is all that is required. Neck braces and back braces are used to support these structures.
Benign muscle tumors require no treatment, or may be surgically removed. Malignant tumors may require surgery, radiation, and chemotherapy.
Perspective and Prospects
With the increased interest in physical exercise in the United States has come increasing awareness of the dangers of muscular damage that can arise from improper exercise, as well as of the cardiovascular risks that lie in wait for weekend athletes. Warm-up procedures are universally recommended. Individual exercisers, those in gym classes, professional athletes, and schoolchildren are routinely taken through procedures to stretch and loosen muscles before they start strenuous activity.
Greater attention is being paid to the special needs of young athletes, such as gymnasts. Over the years, new athletic toys and devices have constantly been developed for the young: Skateboards, skates, scooters, and bicycles expose children to a wide range of bumps, falls, bruises, strains, and sprains. Protective equipment and devices have been designed especially for them: Helmets, padding, and special uniforms give children more security in accidents. Similarly, adults should take the time and trouble to outfit themselves correctly for the sports and athletics in which they engage: Joggers should tape, wrap, and brace their joints; and cyclists should wear helmets.
Nevertheless, the incidence of sports- and athletics-related muscular damage is relatively high, pointing to the necessity for increased attention to prevention. The growth of sports medicine as a medical specialty helps considerably in this endeavor. Physicians and nurses in this area are trained to deal with the various problems that arise, and they are often expert commentators on the best means to prevent problems.
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