Central Pain: How Can a Paralyzed Body Hurt?
Currently, the most attractive theory is that there is a template in our brains that defines normal sensory input. This template requires that the various pain tracts--the posterior columns, the spinothalamic tract and so on--be balanced. When imbalance occurs--a discordance between the normal template and the incoming signals--a pain message is generated.
After the brain detects indistinct or confusing pain signals, it recruits additional brain matter to try to sort out the situation. This recruitment (called the NMDA system) becomes so powerful that it can kill brain cells. To avoid cell death, a separate inhibitory system (called the GABA system) begins to shut down blood flow to various brain parts. This conflict between the two systems is probably central pain. The pain doesn't make sense, but it exists.
This theory, which could in time prove to be valid or totally spurious, provides a hint at how a person without sensation--a quadriplegic, for example--can nevertheless experience pain.
The pain isn't "in your head," but it is in your brain.
Central Pain: What It Feels Like
If you think you have central pain, it may be helpful to know that seven types have been identified. Here are some descriptions gathered from people with each type. Any or all of these pain types can overlap.
Burning dysesthesia: A mixture of pain sensations in which persistent light touch is perceived as a thermal sensation. It can be approximated by injecting capsaicin under the skin. There are four overlapping subtypes.
Burning: "A chemical, not a purely physical burn"; "A mentholated burning"; "Like the skin of my legs has been destroyed and the charred flesh turned up at the edges"; "Like all kinds of tissue damage all at once, with burning worst"; "As if my body belongs to something else which is burning it up with fire and acid"; "I exist to burn."
Cold: "Like touching dry ice"; "My hand tells me the skin of my legs is cold, but it feels like burning"; "Sometimes I know the burning is the draft of the car air conditioner, but other times I forget that my skin must be cold when it burns."
Metallic: "Like tinfoil under my skin"; "Like I am touching an incredibly cold pipe in a freezing night, so that it drains the flesh and burns me"; "Like a dentist is touching the nerve in my tooth, only very cold"; "Like chewing tinfoil."
Wet: "When I am sweaty, my skin is really sensitized and I feel wet and uncomfortable underneath the burning."
Motor or Kinesthetic Dysesthesia: A feeling of cramping and contraction associated with burning. "A terrible fatigue in my muscles, even though I can't move them"; "A feeling of drawing, pulling, crushing."
Hyperpathia: Heightened response to a noxious stimulus. "If I get exposed to a sudden cold draft, or cold rain hits my skin, it just knocks me over and I recoil at the cold pain"; "I usually feel very little in my feet, but if someone sticks me with a pin, it feels terribly, terribly sharp."
Allodynia: Pain from a very mild stimulus. Can also describe referred pain. Can relate to touch, location, temperature or muscle loading.
Touch: "Light touch from clothing becomes unbearable after a few minutes, like an awful sunburn"; "Paper laid on my legs begins to burn unbearably after a minute or so."
Location: "If the room is hot and I rub my palm against the whiskers on my face, I feel burning on the outside of my forearm"; "If I sit long enough for the skin of my bottom to burn, I also feel burning out to the side on my legs and behind."
Thermal: "If I pick up a warm drink, it feels hot in my hand"; "Warm ambient temperature sensitizes my skin so that all the other pain features appear more easily."
Muscle loading: "Movement makes me unbearably sore, so I avoid it"; "The day after I try to exercise, I have awful feelings of lactic acid buildup"; "It feels like I have been sleeping on rocks."
Shooting or Lancinating: Sharp stabbing pains with an electrical quality. "Like electricity shooting along a nerve"; "Like being stabbed."
Circulatory: A very common type in which circulation feels compromised. "I have the feeling of pins and needles in my limbs if I place them on something."
Peristaltic: Feeling of fullness, cramping, nausea or distention. "My bladder burns suddenly"; "My gut feels like it is going to explode."
What science can't do, doesn't know and won't learn unless you speak up
By Kenneth McHenry, M.D.
Pain hurts. All pain hurts. Try telling someone your pain is worse than theirs, and you will encounter real resentment. Everyone has had pain, and everyone knows it was tough.
Yet most of us concede, even if only in imagination, that some kinds of pain are tougher than others. Being severely burned might be an example, or pain that never ends. Another example--for those who have it--is central pain, experienced by some people with spinal cord injury and several other conditions affecting the central nervous system.
Not all people with these conditions have pain, and not all pain caused by these conditions is central pain. But because of its chronic nature, profound severity and the absence of effective treatment, central pain remains one of medicine's great unsolved problems.
Central pain is a bizarre mix of burning and cold made worse by light touch. It cannot be described in ordinary words, but is undeniably real. Neurosurgeon Ron Tasker discovered that central pain results from injury to the spinothalamic tract of the spinal cord; his research led him to characterize it as "the worst pain known to man." Its severity is confirmed by several studies reporting that people with spinal cord injury and central pain commonly consider their pain more disabling than their loss of mobility. What a statement!
There is a story about Pope John Paul II visiting a gas chamber where Jewish prisoners had died. He knelt on a narrow cement landing at the bottom of the stairs and prayed. When asked why, he replied that human suffering had rendered the place holy. Sometimes it feels that way when talking to people with central pain. Their suffering conveys something holy about the human condition. However, they may not feel very human. They're more likely to say they feel as if some alien force has taken over their body and turned it into an engine of suffering. They feel they have lost their identity.
The foregoing is intended not to portray people with central pain as objects of pity, but to allow them to be who they really are and to speak their condition as it really is. As we will see, speaking about pain may well be our best hope for cure.
The Great Oxymoron
Astoundingly, it was not until the 1970's that researchers realized that nerve injury pain was different from normal pain. How could this possibly be?
One reason is that doctors working in clinical settings frequently tell their patients they have "spinal cord injury pain." Since nearly all pain traverses the spinal cord, this is about as specific as telling them they're sick. By adopting the term "SCI pain," we cloak the unique phenomenon of central pain in anonymity. Anonymous diseases don't get studied.
Even so, central pain occurs in large numbers of people with conditions that are anything but anonymousñparalysis, paresis, stroke, multiple sclerosis and other diseases that eventually reach the central nervous system. There are, of course, qualified scientists studying these ailments, yet most lack the credentials to study the basic mechanisms of central pain. Research dollars continue to flow to the scientists researching the "primary" conditions, not to those trained to study the pain those conditions cause.
And central pain is a contradiction in terms that defies traditional theories of how pain operates. It does not respond to morphine or other opiates. More puzzling, the central nervous system is not thought to be capable of feeling pain. Yet central pain is not imaginary; it results from injury to the central nervous system. As a consequence of our widespread innocence of the facts, there is no effective treatment. And very few, including many doctors, have even heard of it.
At one time, there was an old saw among neuropsychologists that human thought can take place only with words. Since newborns have no words, they supposedly have no thoughts. Sound crazy? Compare it to this false assumption: Since patients with central pain have no words to describe their bizarre pain, it probably doesn't exist.
The eye is "the great monopolist of the senses," and doctors don't believe what they can't see. Until PET scans revealed that central pain can cause reduced blood flow to certain parts of the brain--and can even cause them to shut down--it was an uphill battle convincing doctors that something terrible was going on. And until we create a better awareness of central pain--with a credible vocabulary for describing it--a cure will remain elusive.
How can we inform the public so that decent society can respond? How can we inform physicians so they can correctly diagnose the condition? How can we inform medical researchers and policy-makers so that research dollars can be directed toward finding a cure? At present we can't, because we lack the vocabulary for describing central pain.
One ongoing educational effort is painonline.com, a Web site dedicated to the study and cure of central pain. It collects verbal descriptors from people who have this pain and makes them available to researchers. For this it needs input from everyone with central pain. Your verbal descriptors will help medical science make sense of what, on the surface, seems to make no sense at all.
Speaking of Pain
Torture, when tolerated by the public, is a crime against humanity. And central pain, in the absence of steps to correct it, is a societal scandal. But society is unlikely to allocate resources to a need it knows nothing about.
This brings into question our individual coping styles, the ways we cope with pain. Society, psychology and rehabilitation all conceive that there is a "proper" way to cope with pain. Generally speaking, it relies upon high motivation, stoicism, being "productive" (read "working") and distraction through exercise.
But how do these notions apply to someone in a constant state of pain? Even the strongest person will be exhausted by 48 hours of torture, and will need to find a psychological space that permits simple survival of self. A person with central pain can be left with a radically diminished core of existence, and must fight with everything available to maintain it. How does keeping a stiff upper lip serve such a person?
It doesn't. Pain is an impolite and boring topic to others, yet people with central pain will contribute nothing to finding a cure if they bury their suffering in politeness simply to spare the sensibilities of others. Politeness may please our doctors, but it is utter cruelty to those who follow after us. It is part of what has caused central pain to be worded out of existence and out of consideration for research dollars.
There is a time to be gracious and a time to raise Cain. This is a time to scream bloody murder until society finally becomes aware of the shame of central pain and moves toward finding a cure. We will do more for ourselves and for others by making our experience known than we ever will by going from clinic to clinic looking for a miracle cure.
Suffer "properly," and you will sentence future generations of people with central pain to a torment just like yours. Cry out, and you and they may be rescued.
Communicating with Your Doctor
Whether or not coping "properly" is a valid proposition, the truth remains that the medical profession seldom distinguishes between the coping skills needed for a motor disability and those needed for chronic pain. It is like the old saying, "To a child with a hammer, everything looks like a nail." It can take courage to point out to a professional that different strategies are required for pain than for motor impairment, but it may be the only way to get a helpful diagnosis.
Who can forget Bette Lou Hamilton, whose pain drove her to seek out Dr. Jack Kevorkian? The press reported her as saying that she felt like she had been "put on ice and then placed in a fire and then stabbed with a million ice picks"--a classic description of central pain. Hamilton had 10 unsuccessful surgeries before she visited Kevorkian, yet because her description of her pain was "bizarre," one doctor even questioned--postmortem--whether her pain was real.
Central pain is bizarre. It has its own language, and it doesn't make sense to clinicians because it doesn't conform to their own experience.
Even if your doctor respects and believes your description of your pain, it is often tempting to describe only what hurts right now. That complicates the job, because a complete history is needed. Don't be reluctant to be repetitive. A consistent picture is helpful.
You should ask your doctor to diagnose what kind of pain you have. But therein lies a problem, since clinicians often don't know what kinds of spinal injury pain exist. Pain, paradoxically, is not one of the subjects taught in medical school. And, as noted above, "spinal cord injury pain" is hardly a diagnosis. Until you have been told what kind of spinal cord injury pain you have, you haven't been told what's wrong.
If we hope to avoid worthless therapy, we must be precise in the words we use to describe our pain. If we tell our doctor we have "burning," that's already misleading. We know what conventional burning feels like, and we know this is different. But we don't say that because we are so needy of our doctor's validation that we use conventionally acceptable terms. We would do better to use the most accurate language we can, no matter how crazy it sounds. If there are no accurate words, it is perfectly OK to say, "I have pain I can't describe," but don't let your doctor off the hook. Say you want to work together to create a new pain vocabulary.
Aleksandar Beric, at the Hospital for Joint Diseases in New York, has brought some order out of chaos by describing three types of pain caused by spinal cord injury: transitional zone pain, double lesion pain and central pain. Your clinician at least owes you the information as to which of these you have, and what treatments, if any, are available. But keep in mind that the categories are not mutually exclusive--you can have more than one kind of injury and more than one kind of pain.
There are treatments of varying effectiveness for transitional zone pain and double lesion pain, especially when some or all of the pain is generated in peripheral nerves. For central pain, there is no effective treatment. (A possible exception is central pain from syringomyelia--a cavity in the spinal cord--in which relief is sometimes obtained if the cavity can be collapsed.) Sedative drugs are often prescribed to quiet the central nervous system, and you have a right to ask for them if you think you can live with their side-effects. If there is injury where the nerve roots enter your spinal cord, a DREZ (dorsal root entry zone) procedure [see NM September 1995] may provide relief, but the surgery is not always successful and risks further loss of motor, bladder and bowel function. Ask your doctor to explain all options.
Painonline.com offers one more communication option. Suggest that your
doctor download the Web document painonline.com/doc.htm--a description of central pain written specifically for physicians--or download and present it yourself. You may well get more knowledgeable care.
Directing Research Dollars
In my opinion, nothing truly beneficial will happen until a blocker of chemical neurotransmission is produced. The problem is finding the chemical messenger of pain; manufacturing the blocker is, relatively speaking, a piece of cake. It is the hunt for the chemical weapon in the spinal cord, not the chemical weapon in Baghdad, that must catch our nation's interest.
There is hope. See the accompanying sidebar for a description of some very important recent research. To bring this and similar work to fruition is going to take a lot of money and a lot of pulling together. What cures one of us will cure all. The conditions that cause central pain may be diverse, but if we allow our pain to be split off into those separate conditions, then we have lost the power that unity can confer. What we need is an advocacy group large enough to get attention.
It is vital for every person with central pain to become involved and pressure Congress to allocate funds. Write letters to your lawmakers and key members of Congress asking them to fund pain research. You'll find links and addresses for them at the painonline.com Web site. Lobby especially House Speaker Newt Gingrich, R-Ga., Rep. John Porter, R-Ill., and Rep. George Nethercutt, R-Wash., the leading figures in allocating funds for the National Institutes of Health.
In our bodies lie important clues to the cure for pain--a triumph for people with many diseases and for all mankind. We may not get our lives given back to us, but we can ask that society devote enough funds for research to render our suffering purposeful. The payoff will be the biggest victory man has ever achieved--the victory over pain.