Pain

Although MS generally is considered to be a painless disease, more than 50% of people with MS find that pain is a problem, and for 10 to 20% it is a significant problem. Pain appears to result from what might be termed short-circuits in the tracts that carry sensory impulses between the brain and the spinal cord.

Trigeminal neuralgia occasionally is seen in individuals with MS. This severe, stabbing facial pain usually is treated with carba-mazepine (Tegretol®), which appears to "calm" some of the short-circuiting in the sensory areas. To avoid its primary side effect of sleepiness, the medication initially is given at low doses and slowly increased to a point at which it adequately controls the pain. Other medications that may be used to control trigeminal neuralgia include phenytoin (Dilantin®), whose action is similar to but milder than that of carbamazepine; baclofen, which most commonly is used for spasticity; and Cytotec®, a medication that is taken for gastric distress. Newer anticonvulsants (used for epilepsy) that also can decrease neuralgic pain include Neurontin®, Trileptal®, Keppra®, and Gabitril®.

If medications fail to control pain, a surgical procedure may be performed to eliminate the pain, leaving a much less disturbing numbness in its place. This procedure, called percutaneous rhizoto-

my, is performed under local anesthesia with laser technology. Although it is not the first line of therapy, it is viable as a backup.

Occasionally, an unusual "electrical" sensation is felt down the spine and into the legs when the neck is moved. This is a momentary sensation, called Ehermitte's sign, which usually is surprising and disturbing. It is a signal of loss of myelin within the spinal cord in the neck region. It has no significance in terms of predicting the course of MS.

The predominant type of pain seen in MS is a burning, toothache-type pain that occurs most commonly in the extremities, although it also may occur on the trunk. The same medications that are used for trigeminal neuralgia are used for these burning "dysesthesias," but they appear to be less effective than they are for this burning pain. An antiepileptic drug, gabapentin (Neurontin®), has become a useful treatment for this type of discomfort. In doses of 1800-2400 mg per day, gabapentin significantly lessens the pain with relatively minimal side effects. Neurontin® has a very short half life of four hours which means that half of it is gone every four hours. From a practical point of view this means that the medication usually must be taken at least four times a day. It also means that enough must be taken to be effective. That amount is highly variable. Some people with MS have found that antipain cream (Zostrix®, or capsaic acid) may be helpful.

Electrical stimulation (transcutaneous nerve stimulation, or TNS) applied over the area of pain occasionally provides relief. However, it frequently has the opposite effect and therefore is not often recommended. Acupuncture may be helpful for the pain associated with MS but, unfortunately, even in the best of hands it usually fails over the long term.

Mood-altering drugs such as tranquilizers and antidepressants may be effective in some cases because they alter the interpretation of the message of pain. Several such drugs are available, and some relief may be provided with careful manipulation of the type and dose. Amitriptyline (Elavil®) is the best known of these medications.

Additionally, biofeedback, meditation, and similar techniques may be of help in specific circumstances. Because pain is a symptom that clearly increases in severity when it is dwelt on, a con certed effort to treat the reaction to pain is an important part of the overall treatment plan.

What is clear is that standard pain medications, including aspirin, codeine, and narcotic analgesics, are not effective because the source of pain is not the same as the pain that occurs with injury. Pain medications are therefore to be avoided. They are not only ineffective but also addictive.

Although "MS pain" may be severe and bothersome, it usually does not lead to decreased ambulation and is not predictive of a poor prognosis. In fact, those who have these unusual sensations as the major feature of MS tend to do better than average in movement activities.

Severe pain can result from spasticity and spasms. Management strategies for these are discussed in Chapter 4.

Low back pain is one of the most common symptoms treated by the neurologist, and it therefore is not unexpected that it also is relatively common in people with MS. MS in itself rarely causes low back pain; it more commonly is the result of a pinched nerve or another problem. This situation occurs fairly frequently because of abnormal posture or an unusual MS-related walking pattern, which places stress on the discs of the spine (padlike structures that cushion the areas between the vertebrae). This stress may cause "slippage" of the discs, compressing one or more of the nerves as they leave the spinal cord and resulting in pain in the part of the body that is innervated by these nerves. Obviously, heavy lifting and inappropriate turning and bending compound the problem. These movements irritate the spinal nerves, causing the muscles on the side of the spinal column (the paraspinal muscles) to go into spasm; it is this spasm that causes low back pain. If a spinal nerve is significantly irritated, the pain may extend down to the muscles in the leg that are served (innervated) by that nerve.

If the problem is one of poor walking posture, the pattern should be corrected; if spasticity contributes to the problem, it must be lessened. Local back care with heat, massage, and ultrasound waves frequently are helpful, and exercises designed to relieve back muscle spasm may be recommended. Physical therapists and chiropractors who are sensitive to the problems associated with MS may speed healing. Drugs designed to relieve back spasms also may be used, often in conjunction with nonsteroidal antiinflammatory medications (for arthritis). If the problem is the result of a severely damaged disc, surgery may be needed to relieve the spinal irritation.

A person with MS and back pain should avoid severe spinal manipulation or spinal adjustments (rapid twisting or pushing of

A person with ^MS and back pain should avoid severe spinal manipulation or spinal adjustments (rapid twisting or pushing of the spinal column).

the spinal column) because they may irritate the spinal cord, increasing the neurologic problems.

It is critical that a correct diagnosis of the cause of any type of pain be made to ensure that it is properly treated. Diagnostic studies that include magnetic resonance imaging (MRI) and computed tomographic (CT) scanning may be needed to pinpoint the cause of the pain.

Other types of musculoskeletal problems of an orthopedic nature are commonly seen in MS. Ligament damage may result if there is too much knee hyperextension during walking. The knee may swell and may be very painful. Many orthopedic specialists are unfamiliar with MS and do not understand why this related problem occurs. As a result, they may recommend exercises such as "quad sets" to increase the strength of the weak leg. Unfortunately, if strength could be put back into the leg, the problem would not have happened in the first place! Exercising the leg with orthopedic exercises actually produces fatigue and increases weakness. Thus, the exercise program fails. A more appropriate approach is to take the load off the leg with an assistive device such as a cane or a crutch. A knee brace may be necessary and helpful to prevent hyperextension.

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