Just as there is spontaneous and evoked burning dysesthesia, there is spontaneous and evoked cramp in the muscles in fully elaborated Central Pain.
About ten percent of those with central pain in the muscles report what we have chosen to term, “inducible cramp” (see below).
Let us first compare the constant and evoked cramps.
A good many CP subjects complain of a CONSTANT permanent cramp somewhere in the body. These cramps do not change location. They may be anywhere in the area of damage but we have not received reports of any permanent cramps (sometimes termed tightness, drawing, or pulling) which are above the level of cord injury, nor are they migratory, although they can and usually do occur in more than location.
Patients may also have INTERMITTENT cramps. When intermittent cramps reoccur, the CP patient recognizes the nature and location and usually can identify (even if imprecisely) the precipitating cause or position which led to the cramping.
The permanent cramp, of course, remains in the same location and is not particularly capable of being evoked. It is what it is. By comparison, intermittent CP cramps are dynamic, relating directly to a posture, position, or if random, can usually be relieved by a shift or change in position or activity.
Although amenable to EMG studies, we are not aware of any investigations to determine whether permanent cramps are actually muscle contractions or whether they are the perception of contraction. They certainly feel just as real as the “charley horse” athletes feel in the legs, but they are much more likely to come in the thorax, particulary in the chest, or legs.
On the other hand is the evoked variety of INTERMITTENT cramp. This variety is most definitely migratory and inducible. They may occur from the toes up to the face. Sometimes postural causes may be identified (attempting to lean over, positions of the feet or legs, reaching, holding, etc). This type of cramp is triggered by something, but it is not always clear exactly what has caused them. Sometimes the mere shifting of positions may relieve the cramp. At other times, the attempt to massage the area may give relief to the cramp, but this is not universally so. They are transient, lasting less than thirty minutes and usually less than five minutes, coming in episodes of a minute or so. They may come more frequently over several days, and then not appear again until some future postural event summons them up again.
Because it is nearly impossible to do an EMG study while the transient cramp is going on, it is not clear whether an ACTUAL cramp is occurrring or merely the sensation of a cramp. These certainly feel like the real thing, but they do not generally cause a hardness which can be identified as a cramp.
Another variety of cramp is the spontaneous, VISIBLE, contraction of a muscle which is a type of tic somewhere. This always causes a visible twitch of the muscle and lasts from seconds to minutes and also comes in clusters, being present for a day or so, and then fading away. At least in the first few years of CP, it is not uhusual for a lightning pain to shoot from the location of a twitch. Most CP subject with twitch also feel constant, shifting, multiple areas that are doing a runup to a twitch. If these were visible they would be called formications. However, the muscles in such people are never really quiet with dozens of shifting areas active at the same time, creating a sense of fatigue and heaviness (exhaustion) in the muscle.
The inducible cramp, by contrast, is more or less “available on demand”. It can be created with certain identified postures more or less at will, without periods of increased or decresed tendency such as are seen in the non-visible intermittent cramp just described. Patients typically learn to avoid bending over forwards or performing whatever motion leads to the inducible cramp.
Sometimes SCI subjects have spasms. These are more common in those who also have autonomic dysfunction (sweating, high blood pressure etc). It is not known how these relate to inducible cramps. Such individuals may find more or less predictable episodes of flailing or movement, sometimes violent, which accompany such things as transfer to another position, intentional behavior, being touched, or even sequential sexual behavior. Some have even learned to take advantage of the movement to accomplish a motor task, such as movement to a wheelchair. This behavior is more in the order of movement and is not the same thing as inducible cramp. Spasms are definite movements, while inducible cramp is more a sensation of cramp and no movement accompanies it.
Inducible cramp is more a phenomenon than a torture. CP subjects do not include it among the debilitating pain issues attendant to the condition and certainly do not equate it with the devastating suffering of burning dysesthesia.
We have then:
1) Inducible cramps. Posture related, painful enough to warrant a change in position as soon as is practicable, intermittent, and induced by positions which have induced them formerly.
2) Twitch, associated with lancinating (lightning) pains in a small number of the twitches, with nearly constant invisible low grade contractions going on in the muscles. Since the subtle contractions are too numerous to count and there is never a time when the muscles feel “quiet”, it is not realistically possible to say what percentage lead to a lightning pain, but it is very small. Lightning pain is the most intense of the central pains, but is intermittent and does not cause much suffering compared to the burning dysesthesia, just as being jabbed with a needle occasionally would not compare to being set on fire. Lancinating pains of CP are identical in every way to the “lightning pains” of neurosyphilis. Because they sometimes cause a jolt or sudden movement, with possible outcry, they are adjudged to be a serious complication in syphilis. However, since CP subjects suffer so much with burning dysesthesia, lightning pains are considered minor pains in this most major of pain states. The CP patient, although startled by them, usually makes no comment and no complaint.
3) Permanent cramps. These tend not to diminish over time, are identical to a very firm cramp, and do not change location, magnitude, or character. Their magnitude is unpleasant, but again, nowhere near the problem of burning dysesthesia. If they occurred in a normal person, they would seek medical help, but CP patients commonly omit mention of them.
We do not include here muscle soreness, fatigue, sense of heaviness and other disturbing muscle sensation which have already been covered elsewhere under “isometric kinesthesia”, “kinesthesic dysesthesia” and “isotonic kinesthesia” (see using SEARCH). As already noted, Beric has shown that kinesthetic dysesthesia may be so severe as to cause paralysis even with an intact motor unit. We thank the CP sufferes who have completed the surveys carefully. Without them, knowledge stands still on Central Pain symptoms.