While pain is, thankfully, not a major symptom of most neuromuscular diseases, it can be a problem for many people who have these disorders.

Pain is a central aspect of several neuromuscular diseases, and a secondary consequence of muscular changes in others. In all these situations, pain can make it more difficult to cope with the challenges of living with a disorder. Pain that prevents normal motion or disturbs sleep interferes with the body's ability to maintain health.

INFLAMMATION

For those with polymyositis or dermatomyositis, muscle pain often accompanies the inflammation at the heart of these diseases. In the myositis diseases, the immune system mistakes certain parts of the muscles for foreign tissue, and responds by attacking them with chemicals that kill the muscle cells. The result of this attack is called inflammation, and is marked by tissue swelling, tenderness and pain in the affected areas.

Prednisone, a synthetic steroid drug, suppresses the inflammatory response and is often prescribed to combat the effects of myositis. Reduction of inflammation also reduces the associated pain.

Pain is also a central symptom of the metabolic diseases of muscle, such as phosphorylase deficiency, debrancher enzyme deficiency and mitochondrial myopathy.

In these diseases, the normal energy-producing reactions in muscle cells are interrupted, preventing quick resupply of the fuels needed for strenuous activity. As a result, even moderate exercise quickly exhausts the muscles; pain and cramping often ensue, and can last several hours. Little can be done to ease the pain except to wait; it fades on its own over the course of an hour or more as the muscle returns to its normal resting state. People with these diseases learn to monitor their activity levels to avoid the kinds of exercise that bring on pain.

CRAMPING

Cramping is also a painful symptom in other neuromuscular diseases, including ALS. These cramps result not from fuel exhaustion but disorders in nerve cell control of the affected muscle.

Cramps often occur at night, when muscle is at rest. Some people find that 1-2 tablespoons of brewer's yeast before bedtime helps prevent night cramps.

Infrequent cramping is most easily treated by passive stretching of the affected muscle; application of ice may help. More frequent cramping can be treated with phenytoin (trade name Dilantin) or carbamazepine (trade name Tegretol).

Each of these drugs reduces nerve excitability. Unfortunately, they can't be used by people with heart abnormalities, a common problem in some neuromuscular diseases. Those with myasthenia gravis also should avoid these drugs, as their effect can make myasthenic symptoms worse (though cramping is rare in MG). People with other neuromuscular disorders should consult their doctors before using these medications.

The same cautions apply for quinine, an over-the-counter medication used for years to treat leg cramps. It's now difficult to find, having been removed from the market by the Food and Drug Administration because of questions concerning its effectiveness. Those with frequent cramping may wish to try cutting back on stimulants such as caffeine, which can overexcite muscle.

PROLONGED CONTRACTIONS

Myotonic dystrophy (MMD) involves a different sort of cramping - muscles relax very slowly after contraction. While this is rarely painful for voluntary muscles, it can lead to painful conditions if involuntary, or "smooth," muscles are involved.

These include the muscles of the digestive system. Prolonged contraction here can lead to painful abdominal cramps and constipation. Gallstones can form if the smooth muscle of the gall bladder is involved.

Here again, the available anti-cramping medications can help, although it is especially important for those with myotonia to consult a physician before using these drugs, since heart conduction and rhythm problems are a common and serious problem in this disease.

A healthy diet may help avoid some of these problems: High-fiber foods help to minimize constipation, and low-fat, low-cholesterol foods cut down on gall bladder activity. Surgery may be indicated in some cases.

Finally, cramping can sometimes be a good sign in myasthenia gravis. In MG, the normal nerve cell signaling molecule is broken down before enough of it builds up to cause muscle contraction. The drug Mestinon is often prescribed to delay the breakdown; cramping is a sign that the drug has begun to work.

SKELETAL PROBLEMS

While the muscle wasting of the muscular dystrophies does not itself cause pain, the resulting muscle weakness often leads to changes in posture which, if uncorrected, can be quite painful.

When skeletal elements shift out of their normal positions, they may stimulate pain receptors in the joints. For instance, facioscapulohumeral muscular dystrophy often leads to shifting of the shoulder joint, as the weight of the arm becomes too great to be resisted by the weakened shoulder muscles. A partial dislocation results, and irritation of the ball-and-socket joint there can lead to chronic inflammation.

Treatment for this type of pain may involve non-steroidal anti- inflammatory drugs (NSAIDS) such as ibuprofen, or a prescription steroid. A sling may help relieve the stress on the shoulder muscle. In many cases, surgery can increase support of the shoulder joint when other methods fail to provide relief from pain.

In Duchenne muscular dystrophy and spinal muscular atrophy, muscle weakness progresses to include those muscles that support the spine and chest.

The resulting changes in posture often lead to scoliosis, or curvature of the spine, a painful and potentially life- threatening condition. Changes in posture put weight on structures unsuited to the stress, and full expansion of the chest cavity becomes difficult, which impairs breathing already made difficult by weakened respiratory muscles.

While in the past scoliosis was treated with bracing in the wheelchair, current recommendations are almost unanimously in favor of early surgery to prevent the curvature before it becomes severe enough to impair breathing. (Scoliosis surgery will be the subject of a future article in Quest.)

Surgery, of course, can bring its own painful complications. The person with neuromuscular disease facing surgery, whether for treatment of disease-related problems or not, will need careful evaluation for the planning of anesthesia and control of post- operative pain.

For instance, certain anesthetics increase the risk of malignant hyperthermia, a rare but potentially serious complication during surgery. Opiate pain relievers such as codeine and morphine suppress normal respiratory function, decreasing breathing rate and depth. This can be life-threatening if the respiratory system is already weakened by neuromuscular disease. Many anesthetic agents normally used in surgery are unacceptable for the same reason. It's important that the medical team plan for pain control with full knowledge of the patient's medical history.

HEADACHES

Of course, people with neuromuscular disease have the normal range of other medical problems not related to their disorder.

Pain can arise from headaches, fever, menstrual cramps, arthritis, etc. Treatment with non-prescription medication is usually as effective and as uncomplicated as for those without neuromuscular diseases.

However, there are some caveats. Aspirin and NSAIDs can cause gastrointestinal bleeding. These drugs should therefore be avoided by those on prednisone, which can have the same side effect; acetaminophen (for example, Tylenol) can be substituted. Aspirin also shouldn't be given to children with fever, as a rare condition called Reye's syndrome may result.

Atropine and scopalamine are present in some over-the-counter drugs for constipation and allergy. Because they affect transmission of nerve signals to muscle, they should be used only after consultation with a physician.

ANXIETY

Finally, the psychological pain of anxiety or depression can be a major consequence of a neuromuscular disease, and its treatment is every bit as important as is the treatment of physical pain.

For the person finding it difficult to accept his diagnosis, or who is anxious or depressed about the future, proper counseling and family support are critical. MDA support groups are an important resource for those learning to cope constructively with the challenges of life with a neuromuscular disease.

Several nationally renowned physicians who are experts on neuromuscular diseases provided information for this article. For advice on an individual case, always consult with a personal physician.