How distal is distal?

Work in Complex Regional Pain Syndrome highlights similar difficulties in clinical evaluation of central pain. The terms to describe Central Pain are themselves so vague as to require explanations about what they mean as applied to CP. CRPS can help.


This article is an undisguised plea for you to submit your answers to the survey here and to resubmit as many times as you notice something new, merely indicating that this is a resubmission, so we keep our data straight.

Given today’s super fast paced evaluation of patients, it seems ludicrous to even bring up the necessity for painstaking clinical evaluation of patients. If a machine won’t do it for us quickly, and we mean REALLY quickly, managed care simply isn’t interested and is, in fact, quite put out. No doctor is permitted to act otherwise, and stay on the panel, and since patients are now OWNED by managed care, the government having allowed us to be placed on medical plantations by the inane HMO laws, any disease condition which is involved, like CP, is SOL. Like a herd of cows, we have our turn at the trough and must then move on, herded along by physicians assistants, and others who “AID” the doctor in “managing” our care.

In case you missed the point, “managed” is a euphemism for “LIMIT” our care, measuring it out in Scrooge like fashion, while the administrators grow fat for doing nothing medical. The person who owns the ball makes all the rules, and the hospital owners are now heartless businesses, who wrap themselves in the shawl of medical care, but don’t even know how to carry a bedpan. Disgusted by the idea of being a “lackey”, most bright students have long since passed up medicine for dentistry or some other field where some obnoxious administrator doesn’t lord it over them all the day long.

Only on television do articulate sexy geniuses inhabit hospitals. In real life, the automatons who would not and cannot rock the boat populate the hallways, beginning a programmed mental chant the moment they lay eyes on you, “MUST NOT SPEND TIME WITH THE PATIENT”. Even the “physician expanders” (which means kiss off any idea you had of seeing a doctor) follow this strict commandment of the top brass, and it all costs you a fortune. How the politicians ever allowed this to happen is a mystery– one which they will not ever have to solve, since THEIR medical insurance provides limitless care.

MOST of the CP syMptoms do not require elaborate histories. Only the dysesthetic burning is really so complicated, being a mix of pain sensations. The problem with the rest of the symptoms is simply that there are so many to be covered, each with its own distribution and quality and each as a target for therapy. ONLY the burning dysesthesia has a clear distal predominance, meaning that it gets much worse as one goes OUT away from the spinal cord or nerve origin site. It has become commonplace to use the term “distal” to describe the increasing pain as one move further out along the extremity, face, or whatever.

The early French researcher Dejerine, whose associate Gustave Roussy, recognized that this tendency toward the distal was not quite linear in the face. There was little doubt of the increase as one went distally, but on the face, there were zones of what was actually physically distal in the three branches of the trigeminal nerve or CNV. CNV has branches A (eye and above) B (upper lip to eye) and C (lower lip to edge of jaw). Since Central Pain is an incomplete injury, the less severely damaged branch of CNV might actually give the most severe pain.

However the branches were nearly always differentially affected, making what is distal seem to move forward and backward on the face, due to the vertical distribution of the branches of Cranial Nerve Five. Furthermore, the dura around the brain, although sequentially supplied by A,B,C branches of CNV, could nevertheless give difficult to localize CP headaches, and paralysis of the tensor tympani (supplied by CNV–most facial muscles are supplied by CNVII) might cause tones to be heard slightly differently, particularly in the low frequencies of speech, and no distally was appreciated there, unless it be the preference for interference in low tones, heard at the opposite ends of the cochlea from high tones. Dejerine therefore used the term “onion skin” to describe the zones of increasing or descreasing burning. The significance of the term “onion skin” seemed better suited to the varied way patients presented.

As to the extremities however, Dejerine used “distal” just as did Roussy. Unfortunately, many clinicians today have no idea what Dejereine was talking about and since physicians today no longer travel to the continent to enhance their education, do not speak French, and do not read Dejerine and Roussy, although they would learn a great deal clinically about Central Pain, if they did. George Riddoch was the heir apparent to the Frenchmen on pain of central origin, but Riddoch was so alarmed by the severity of central pain that he could not find words to encompass it, making him sound a bit hysterical (matching his patients of course) writing in the Lancet, resulting in his being more or less ignored on CP even as he was lionized in other areas as a great neurologist.

It was not until Tasker discovered that pain travels in the spinothalamic tract, and John Bonica and Carlo Pagni became interested in central pain, that it was once again taken seriously, if indeed, it can be said to be taken seriously today. There is no doubt that the PhD researchers are fascinated by it, now that they have an animal model. As to the clinician, the interest is more than spotty, it is rare as diamonds, making the physician who is truly knowledgeable about Central Pain very difficult for find as the patient ventures out into the medical wilderness. Fortunately, there are numerous minor varieties of nerve injury pain.

Pain being painful, patients demand help and those in lesser pain take it very seriously and are well enough to be much better advocates and better at insisting that help be rendered.

Flat on their backs, as it were, severe CP patients are the lowest of the low and cannot advocate much of anything since they are hanging onto existence and often too sick to go to the doctor’s office. Furthermore they “LOOK” good, so to speak. Being okay to the eye is the death knell of appropriate care. They really ought to be inpatients, but in this era of same day surgery, we have written out of the textbooks any nonterminal illness requiring hospital care to the end of one’s days. In years past, there were the TB sanitoriums, but today, even for schizophrenia, there is little hope of ongoing care, unless you are incarcerated for some insane crime.

Consequently, CP patients are largely dependent on the pleas of PNI or less affected patients to make the case for pain research. We are sorry they suffer, but are the beneficiaries of their efforts to find cures for other pain states, such as CRPS, tic doloreaux, either of which can make the person almost incapacitated. These localized varieties at least give hint of why central pain, ravaging sometimes the entire body, is truly evil and devastating. The part of the body it ravages most is the distal part, and there, it is really a killer. It is the end of life as is generally known, and so much worse than numbness.

The literature of today are relatively poor on central pain on the face, perhaps because the very complexity of it is outside the reality of the time a clinician is permitted to spend with a patient. Central pain really ought to be a matter of several days examination and history taking. However, fifteen minutes is about standard, and most of all of that will be devoted to the underlying spinal cord injury, stroke, or MS. Consequently, clinicians are more ignorant than ever about the clinical manifestations of central pain. Dr. Patrick Wall was attempting to reverse that trend when he began this database.

This “computerized more meg” thinking of today’s society has tended to eliminated the art of medicine. Clinical evaluation was the poetry of care in the past. The great clinicians of the last century, spawned from places like Johns Hopkins, where Osler said “If you will listen to the patient long enough, he will eventually tell you what’s wrong with him.” The Europeans were no slouches on this either and in fact Hopkins itself was derivative of the great investigative scientists it hired from Britain and Europe, thanks to the urging of S. Weir Mitchell as the early faculty was formed.

Just as the charting of Captain James Cook, or even William Dampier a hundred years earlier is testament to the precision of early naval men, it is sometimes awesome to go back and see how precise and painstaking were the examinations of patients in that era. We will never come that way again. No careful doctor would last a day in an HMO paced medical environment. Bottom line administrators who have offices to carpet and hospital veneers to marble, have no patience for the art of medicine and can stomach technology so long as it is either very profitable or very, very profitable. Still, the early doctors made some bad mistakes due to misguided faith in the word of trusted fellows. We are not downgrading technology. It is simply that the average interpreter of MRI’s has not kept pace with the technology. Does a vertebral disc bulge? Is it abnormal for age. Is the degree of impingement on the thecal sac (dura) significant? Since the technology cannot image the important spinal vessels which run in the spinal canal, who knows?

The radiologist certainly has no time to question the patient and so has no opportunity for feedback. Emergency rooms still irrationally run CAT scans as the first line evaluation of soft tissue injury, preserving the vastly superior MRI for later evaluation for reasons that can only be financial. MRI is best for soft tissue, CAT scans are generally best for solid tissue. What we get instead are plain films for solid tissue and CAT for soft tissue. When they explain that one, somewhere in the calculus will have to be the dollar bill, since it doesn’t make any sense scientifically. CT is good at detecting hemorrhage in the first 48 hours, but since the average ER patient has to wait longer than 48 hours to be seen, they just as well go ahead and do the MRI anyway. (just kidding, just kidding).

Traditionally, clinicians in the various specialties paid almost no attention to the interpretation of plain films by radiologists, since the lack of useful clinical information was a glaring omission from the dictated forms which satisfied official bodies but it was a poor clinician indeed who couldn’t do a better job of interpreting films than a radiologist. The interpretation was more or less a gimmick for radiologists to make a living and also to help doctors outside their area of expertise gain a little information as to what was on the films. The CAT scanner began to change this, being much more complicated and difficult to interpret (although inherently much better at providing information, provided the radiologists rose to the occasion. Then, along came MRI, then functional MRI and now the very technical and “niche” tensor MRI, where no one has really caught up with the imaging.

Information is lost every day from films because we do not provide enough clinical communication with the radiologists. Doctors do not routinely report back from the operating room where the radiologist has messed up. They just politely take note that in the future, this is one area where they will ignore what the radiologist says.

Turning back to Johns Hopkins, this is why the various specialties once had their own individual, redundant xray departments, where for example, an obstetrical resident took his own xrays and developed his own films. Radiologists were not considered capable of doing specialized work. The departments even did their own pathology, or microscopic examination of specimens. This ran into problams when the simple care of patients required such a volume and pace of activity that work simply had to be handed over to the respective specialists.

And so, the whole medical profession is now in limbo. They are not good enough to read their own MRI’s and those who are charged with reading them, do not have time to go and examine the patient. One bright exception is the group known as interventional radiology, which is what every radiologist ought to be, but it requires such rigorous training, we can only take off our hats in admiration at these men and women who not only sip Pepsi while a servant film handler posts them on a rolling viewing screen, they also get off their duffs and go take care of patients. In France, nearly one third of doctors receive training in radiology. This makes perhaps for more ionizing radiation than is really desirable, but it also makes the average doctor conversant in what the radiologist is saying, with an understanding of the pitfalls. Given the extreme need for better clinical (patient) skills in physicians, which has nearly become a lost art, we welcome the impetus among radiologists to become more involved with patient care, although the tendency is not nearly widespread enough. Who wants to spend an hour or two talking to an individual patient for fifty bucks from Medicare, when the same doctor can read a dozen MRI’s in the same time for thousands of dollars. You see that our system of reimbursing doctors has created this mess, where difficult clinical skills are simply not rewarded, but anything technical has reimbursement validity. Either the radiologists and surgeons have to be paid for conferencing or else nearly everyone will need to become a radiologist if the patient is to get ideal care. In neurology, throw in the need for training in electrophysiologic training and you get the idea that trends in science and trends in HMO profitability are definitely in conflict.

That is why we love places like the National Institutes of Health where tough clinical cases can go and the challenge of the tough patient is actually welcome. They don’t pay their doctors anything decent, but fortunately for the patient, the clinicians there still value time with the patient. And to be honest, Johns Hopkins hasn’t lost its appreciation for clinical skills either. The interesting thing is that raw science moves faster at hospitals which emphasize patient contact. So we know we are right when we say clinical skills are still very important. Reduced to common English, that means knowing which questions to ask, and taking the time to ask them.

When Doctor Patrick Wall recognized the incredible time necessary to thread out the symptoms of Central Pain, which are as complicated as any condition could possibly be, he felt that only a computerized database could begin to handle the manifestations. He was joined in this opinion by Dr. John Bonica who proposed tackling the very difficult job of sorting out neuropathic symptoms from somatosensory pains (normal or musculoskeletal pain not due to nerve injury) by computerized databases. That was the genesis of the Wall/McHenry database. at which you now find yourself and in which most of you have participated. Many respondents have commented that they did not notice certain aspects of their own central pain until they read about the features at this site. Of course, that is what clinical medicine is all about, providing proper cues, so the patient can give an accurate history. Now and then a patient will add something entirely new, which in retrospect resonates with other patients, and that is how the field of clinical knowledge grows. We have received grateful communications from many researchers for the directions your information has pointed them. You aren’t making it up. The new technology confirms your expressions, no matter how bizarre some of them may be.

Now we come to one illustrative case. One of the more interesting experiences was to sit in on one of the vigorous debates between Hubert Blumberg from Germany and Jose Ochoa from the U.S. on what was then called Reflex sympathetic dystrophy, now called complex regional pain syndrome, which was even subdivided by Buehl. The debate centered around the relevance of temperature changes in making the diagnosis. Ochoa didn’t think thermography was far enough advanced to include it among the requirements for diagnosis and Blumberg with pride in German precision found thermography very important. Both of them were correct, in their own way, but their interchanges provided an interesting snapshot of how technology requires a little refinement before the clinician can really trust it, then eventually milk it for all it is worth.

A recent article by Niehof et al, see Biomed Eng Online. 2006 May 12;5(1):30, finds that thermography in CRPS must be done in a setting of total body cooling and warming to give significant results. What this means is that the temperature differences between the side with CPRS and the unaffected side don’t really show up unless the sympathetic nervous system is first engaged by warming and cooling the entire body, which will either dilate or constrict the blood vessels respectively. What was interesting is that the temperature measurements were made at the FINGERTIPS. This made us curious and so we contacted some of our old reliables with Central Pain and found some possible information of use in research.

A fair number of people with Central Pain also have some degree of sympathetically maintained pain. Livedo of the palms (blotchiness modifiable by cool or warm water, indicated incoordinated regulation of vasodilatation) can be noted in a significant percentage of CP patients, and a modest diminution of the skin burning can be achieved with heavy IV blockade of the sympathetic nervous system. So there is an interest in those who have only CRPS, because they are cousins to many of us. Early thermographs showed temperature differnces which seemed often to fade out at the fingertips.

Ever since Gustave Roussy in 1907 (along with Egger and Dejerine), we have known that the burning dysesthesia of central pain is worse distally, ie out at the ends of things, (extremities, genitals, etc.) This distal hyperpathia/hyperalgesia/dysesthesia is worst where sensory loss is greatest. However, knowing that when Central Pain subjets say they have acid burn on the skin, they really mean JUST UNDER the skin, and after reviewing Niehof, we interviewed subjects about the meaning of the word “distal”. We found that in many “distal” means “almost distal”. In other words, for those who have severe burning dysesthesia” most severely on the feet, that the burning was most severe nearly to the ends of the toes, but that immediately at the tips, the burning was not any more severe and in many people it was actually less, the very worst burning extended to the tops of the distal phalanx of the toes, but not to the very tips. We then did pin prick testing on the tips for sensory loss and found that sensory loss DID extend to the very tips of the toes. What this would mean on thermography, we do not know. Many with central pain reported that early in the development of the condition, their feet feel swollen, almost to the inability to distinguish one toe from another without something touching them. We have in the past attributed this to atopoesthesia, but it may well be that a separate phenomenon is involved with “distallity”.

In lepers, there is profound sensory loss in the hands, but it is most profound in the ulnar nerve and distally. Brand showed this was due to the fact the ulnar nerve runs closer to the surface of the skin near the elbow and is therefore more subject to cooling. The median nerve, just a little deeper has less sensory loss and the radial nerve, even deeper, and warmer, has the least sensory loss of all. In diabetic neuropathy, the loss of sensation is uniform because different mechanisms are involved in the nerve injury. In central pain, it is not clear why the sensory loss is most profound distally, nor why the burning is most profound. With the frequent instability of the sympathetic nervous system, which controls vasodilatation and therefore affects cooling, temperature effects are a possibility. Dr. Patrick Wall was of the opinion that the distal, more sensitive parts are more richly supplied with sensory nerves and therefore, the thalamus interprets the sensory damage from a greater number of distal nerves and therefore creates the protopathic burning more severely where there are move nerve fibers to begin with. Those with Central Pain on the face from injury to the descending tract of Cranial Nerve V (trigeminal) were not able to find an area at the very tip of the nose, tongue nor of the lips where burning was slightly less. However, all were of the opinion that the burning was probably greatest where the lips meet or just inside the lips, with considerable burning on the gums near the lips.

These results then are not conclusive and do not settle any question on areas of burning. However, if and when thermography becomes part of the Central Pain exam, UNLESS the patient is subjected to total body warming and cooling, the results, like the results in CRPS, will likely not be significant. Since so many CP patients have some degree of Sympathetically maintained pain, it seemed well to anticipate the questions that might arise when thermography scanning begins to be done. Whether CP patients burn most severely on the tops of their feet and toe pads (as compared to the extreme tips of toes and the soles of the feet where sensory loss is equally as great) because that region of the foot has been sensitized by light touch of shoes, because of some circulatory reason, or for an unknown reason, it is necessary to qualify the word “distal” when referring to the feet as “almost distal” meaning the very tips of the toes do not typically burn more severely than the phalanges immediately proximal. Thermography will have to be interpreted accordingly when it begins.

Questions about distallity in the hands gave equally ambiguous results with most reporting greatest pain on the pads of the fingers, as if the tips had been sensitized, which could be explained by using that area to touch things. However, the tops of the hands, the skin over the metacarpals, and the palms were adjudged to burn equally, for reasons that are not clear. Patients were not in agreement on these matters, so individual variation may be great, particularly if the variable of having touched something recently is not included in any study.

Thank you again for the many thoughful responses in the surveys. We read each response carefully. We generally spend more time reading your answers than you spend composing them. That is how language is when you are trying to decipher matters for which no vocabulary exists.