PainOnline - Bowsher's Criteria

The Diagnosis of Central Pain
	The diagnosis of Central Pain is one of the easiest in medicine. Bowsher's criteria easily identify the presence of Central Pain. (Bowsher 1990) Central Pain is characterized by the following symptoms in a patient with an injury to the Central Nervous System, which injury may be determined either clinically or electrophysiologically through Somatosensory Evoked Potentials: Unfamiliar burning pain from light touch, but not from deep pressure. Paradoxically, there is a component of cold. The pain is made worse by rubbing or the touch of clothing. Beyond Bowsher's three criteria is a constellation of neuropathic symptoms, not necessarily painful, which some authors unfortunately place under the rubric of Central Pain. It is misleading to lump paresthesias together with pain since it confuses unspeakable agony with mere strangeness. Non-painful sensations generated by an injured nervous system should be termed central paresthesias, not Central Pain. As one physician said in regard to mixing paresthesias with agonizing burning, "It is like listing Auschwitz in the same category as bad room service". On this Web site Central Pain refers to the classical form, following Bowsher's criteria. Muscle pain is frequently present but is not essential to the diagnosis. Because medical professionals so frequently lack knowledge of Central Pain, the core symptoms named by Bowsher should be publicized until no physician is mystified by the term. Movement pain or postural pain from the muscle spindle is common, and shooting (lancinating) pains are nearly universal. Spindle pain is not commonly taught and lancinating pain is also seen in such conditions as neurosyphilis, so Bowsher's criteria suffice. It is important to realize that many patients with nerve injury outside the central nervous system, such as in a peripheral nerve, may have similar symptoms of similar severity to Central Pain. Peripheral nerve injury pain is called deafferented pain or simply neuropathic pain. Sometimes the term neuropathic pain refers to both central and deafferented pain. Research on either type should certainly benefit the other. Models for both types of pain are relatively easy to produce. Simply exposing a peripheral nerve and crushing it with a clamp will usually yield a deafferentation state. Central Pain, or what is thought to resemble Central Pain, is currently modeled by lasering the spinal cord of animals who have been pretreated with erythrosin-B. For the sake of clarity, and because the patient base described herein draws from those with CNS injury, deafferentation is infrequently mentioned here, but many of the same characteristics describe both conditions.
The Patient Will Not Volunteer the Symptoms
	One of the hardest things for physicians to realize is that the Central Pain patient speaks of sensations by memory. They do not remember what normal touch feels like. This makes taking a patient history difficult, because the Central Pain patient describes their symptoms from a different perspective, that pain is the norm, not normal sensations. Thus, the patient has a radically different paradigm than anything in the realm of the physician's personal experience, and perhaps different than anything in their professional experience. The Central Pain patient compares all sensations to their normal state; severe pain. If a patient no longer remembers the normal sensations they experienced before Central Pain, then the description is deficient. The clinician must follow the categories in the Table of Central Pain or the Mnemonic of Central Pain. The physician must sometimes clarify or repeat questions until the patient remembers how Central Pain felt in the beginning or what they remember as their earliest reactions. The physician must always remember that the patient is describing Central Pain to normal pain not by active discrimination, but by memory. Late in the disease, the clinician is likely to get only a description of the burning dysesthesia and what exacerbates it.
*No Adequate Vocabulary For Central Pain*
	On encountering their first patient with Central Pain, the verbal descriptors used for the symptomatology often are so extreme that the clinician may fail to recognize Bowsher's criteria in what the patient says. The clinician must ask probing questions of the patient. Since Central Pain is a sensation that is new to the patient, they will frequently not use the word pain until the physician asks about physical suffering and then begins to term any such sensation as pain. The patient has had pain before, and it was a very definite and vivid experience. Central Pain is something different from pain as the patient knows it, and so the patient may speak in terms of tissue destruction, torture, unexplainable physical agony or the like, simply because Central Pain is a very different type of pain. Additionally, patient may suffer so greatly from the burning on the skin, and so hope for relief from the same, that severe muscle pains may go unmentioned. Office visits may turn into recurring entreaties for relief from skin burning; so much so that the patient never mentions the accompanying pains and they therefore unrecognized by the therapist as being part of the syndrome. It is surprising how often a physician may treat a Central Pain patient for years without being aware of the range of sensations involved.
Central Pain is a New World for the Patient
	The changes in the patients' sensory world are so profound that they soon cannot remember what "normal" feels like. Because memory fails, it's almost as if the normal world doesn't exist; consequently, they may expect the examiner to understand readily. The patient may not be able to recreate a realistic picture of a normal sensation to compare to their present reality or they assume the physician can understand even though they cannot put their feelings and symptoms into words. The quality of comparative descriptions suffers when the patient cannot remember skin which does not burn, nor touch which is not painful. It is not unusual to watch them mourn nostalgically when they do recall a specific sensation. It is as though they are remembering when they were human. Although the patient will remember the early fear and alienation after contracting Central Pain, they may not remember the specific signatures of the condition in it's early stages which told them something was really wrong in what they felt. Failure to remember normal sensation blunts descriptive precision and increases the likelihood that the nature of present abnormalities may not be well described, since the patient must always borrow terminology to describe their disease. The clinician may need to remind the patient how various experiences used to feel and then ask the patient to describe how those experiences are different with the disease. Again, it is most helpful to go through the list of symptoms in the mnemonic, to provide verbal cues for the patient. The verbal descriptors of Central Pain provided in Riddoch's early paper provide a very good feel for the kinds of expressions patients are likely to use. The Central Pain patient may surprise the clinician if the clinician provides appropriate clues from Riddoch's paper to assist the patient in giving a good description of their symptoms. A famous statement made by Osler at Johns Hopkins states that if you listen to your patient long enough, he will tell you what is wrong with him. The diverse verbal descriptors of Central Pain need more attention to divide them into their appropriate categories. Clinicians must be more specific about sensations, so that research may progress and physicians can evaluate therapies. The clinician must remember that the pattern of one Central Pain component certainly does not match the behavior of another Central Pain component. For example, lancinating pain tends to occur more frequently early in the disease. A physician may mistakenly attribute a decrease in the frequency of lancinating pain to a remedy which is not effective. The physician may then report that the patient's Central Pain improved on drug therapy, when in fact the dysesthetic burning remains unchanged. Dysesthesia and diminution of touch sensation occur distally while hyperpathia is greatest proximally where touch sensation is more retained. Consequently, hasty examiners may record such patients as being either hyposensate or hypersensate, based on various routine neurological tests. Therapy will reflect the quality of the questioning. No one advocating therapies should be content until he has spent the time necessary with patients to determine the presence and behavior of the distinctly separate painful sensations. The medical community must not group the patients with severe Central Pain together with those who have Central Paresthesias. Patients with symptoms limited to tingling or discomfort may need no medication while severe cases will need heavy sedation. Separation of patients into varied categories makes neurologic evaluation of Central Pain patients painstaking and very time consuming, but there is no other way to speak rationally of the disease.