Spinal cord injury (SCI) typically results in sensory paralysis, or a loss of feeling in areas using nerves that connect to the spinal cord below the level of injury. A person with complete paralysis can’t tell if these areas are being tickled with a feather, stuck with a pin, or burned with a match. The lack of pain sensation presents a constant danger; persons with SCI must to learn to compensate with other senses to avoid damaging themselves.
Unfortunately, paralysis does not guarantee freedom from pain. In fact, a number of people with SCI experience chronic pain in areas that otherwise have no sensation.
“Somewhere around a third to one-half of the people who have a spinal cord injury have pain that is severe enough to interfere with their Rehabilitation,” said John D. Loeser, MD, who heads the University of Washington Medical Center’s Multidisciplinary Pain Center.
The exact number varies greatly from one study to another because of the subjective nature of pain, Loeser said. “If you want to know how many people have broken legs, you can x-ray them and find out. But if you want to know how many have pain, all you can do is ask.”
Loeser said he takes the view that people who complain of pain are in fact experiencing it. “I think the number of liars and malingerers in the world is very small; I tend to believe people are telling the truth.”
Types of Pain
There are at least five different types of pain that patients may experience after SCI, Loeser said. The first task, therefore, is to “try to find out what kind of pain you’re dealing with.”
One type of pain is related to mechanical instability of the spine, perhaps produced by incomplete healing of the fracture. This pain is made worse by sitting or moving, and is usually decreased by lying in one position or another. “You can document the instability by the appropriate x-ray tests, and it’s usually directly treatable by either external or internal stabilization,” Loeser said.
A second type of pain, often related to the first type, is mechanical compression of a nerve root at the injury site, caused when a piece of bone or a fragment of disk impinges on the nerve root. This produces radiating pain, often on one side but sometimes on both sides, which is made worse by movement. Magnetic resonance imaging makes it possible to see the nerve and the piece of bone or disk that is pressing on it, so surgeons can operate and resolve the impingement.
The third type of pain is felt by the patient in the totally anesthetic part of the body. A patient with an injury at the T6 level (a few inches below the nipple), for example, might report a burning, aching, or throbbing pain in the legs, buttocks, or genitalia. This pain is constant and is not related to position or activity. “It’s due to the injury to the spinal cord, and is very difficult to treat,” Loeser said. “Sometimes patients respond to drugs, and there may be a role for the direct application of drugs to the spinal cord via intrathecal pumps.”
Loeser said the drugs that seem to work for some patients with this type of pain are anticonvulsant medications; tricyclic antidepressants; mexiletine, a local anesthetic that can be given orally; and, on rare occasions, opiates. “Recently, there has been an attempt to see if delivering the narcotics directly to the spinal cord through a pump would deliver good long-term pain management,” Loeser said. However, he added that the effectiveness of this method “is not at all clear at the present time,” as the two main problems with using narcotics–namely, the development of tolerance and the experience of withdrawal symptoms after cessation of the drug–are still present with intrathecal application.
The fourth kind of pain is a chronic pain that occurs in the region of partial sensation. “Most spinal cord injury patients have a girdle zone where (sensation) is in transition from normal to absent,” Loeser said. “This is a kind of denervation pain. It’s occurring from the segments of the spinal cord that are working but are deprived of their normal input by the injury.”
This type of pain is also difficult to treat, Loeser said. Sometimes drugs are used, and sometimes an incision is made in the spinal cord at the level of injury, producing a Dorsal Root entry zone (DREZ) Lesion to stop the pain signals from reaching the brain.
The fifth kind of chronic pain seen in patients with SCI is due to overuse phenomena that are not directly caused by the injury, Loeser said. “But if you’re in a wheelchair, you’re using your shoulders as if they were hips.” Shoulder problems, biceps tendinitis, Carpal Tunnel Syndrome, and tennis elbow can all be seen in Paraplegic patients who use their arms for mobility, and need to be treated appropriately.
Finally, Loeser said, there is another part of the patient that may affect the presence or severity of pain after SCI: the mind. “People who have had a devastating injury may also have emotional or cognitive factors that can be superimposed upon any of the other pain problems, and can magnify them. One needs to be aware of the fact that the way people feel or think, their thoughts and fears, and how the world around them treats them, can also be a factor in the generation of a pain complaint.”
In addition to drugs and surgery, the Pain Clinic has other techniques for treating pain, including psychological treatment strategies such as guided imagery. Loeser stressed that post-SCI pain is not a psychiatric illness–“It is not due to an aberration in thought or emotion, so it’s not very common that you can treat it with such strategies alone.” However, he added, teaching coping strategies to patients whose pain is intruding into their lives, or dealing with psychological factors that may overlay a pain problem, may help even if they won’t eliminate the cause of the pain.
Some, but not all, patients also find Biofeedback helpful in controlling their pain, Loeser said. One method uses electrodes on the skin to measure muscle activity; another uses a temperature sensor on the patient’s finger. “You teach the patients how to control either their muscles or their temperature,” Loeser explained, “and those strategies sometimes help.”
With or without treatment, Loeser said, most of the SCI-related central pain states appear to diminish over time. “We’re talking about years,” he cautioned, adding that there are also exceptions–he has seen some patients with pain for over 20 years. It is also not clear whether the pain is diminishing or whether the patients are simply realizing that treatment doesn’t seem to be helping, so they stop talking to their doctors about it. “There are lots of potential explanations,” Loeser said.
Loeser said there is a definite need for more research into both the causes and the treatments of chronic pain after SCI. “The data we have say there’s a large number of people who have pain severe enough to impair rehabilitation–the presence of pain, not the Paraplegia, is the major impediment to rehabilitation,” he said. At the same time, patients need to beware of people who promise them a cure.
“Spinal Cord Injury is such a desperate injury that the field is full of charlatans and quacks who promise more than they can deliver. People need to recognize that there isn’t any magic cure. All of our treatments for SCI pain are trial and error…there may be some new drugs or new treatments, but people ought to be intelligent consumers.
“Before they spend money, they ought to ask, ‘Can I talk to patients who’ve had this procedure?’ and ‘Where is this published? Can I read about it? Is it FDA approved?’ If their physician is going to recommend a drug to attempt to treat SCI pain, they should be sure to ask the physician, ‘What are the potential side effects? How long am I going to take the drug before I find out if it’s helping? Are there alternative drugs that might be safer or cheaper?’ Again, be an intelligent consumer.”
John D. Loeser, MD, can be reached at the Multidisciplinary Pain Center by calling MEDCON, a 24-hour, toll-free consultation and referral service for health care professionals and their clients with spinal cord injury, at 206-543-5300 (in Seattle) or 1-800-326-5300 (outside Seattle).