Virtually all pain develops within the periphery following trauma, injury or illness to a body part. In some cases pain is produced in the brain as opposed to in your body. During these uncommon circumstances your body part might have heeled from its original physical injury: nevertheless your brain will keep sensing the discomfort. In such a circumstance we call the condition a central (meaning generated by the central nervous system or brain) pain syndrome. One of the most common examples of this is the so-called phantom limb pain. Phantom limb pain is really a strange ailment that sometimes develops when an individual has an arm or leg amputated. To illustrate this, say that a person losses his left lower leg as a result of some trauma. It is not at all uncommon for such people to report feeling pain in the left foot or toes, even when they no longer have a left foot or toes. The leg is gone, but the rendering of the leg in the brain still continues. Consequently if that section of the brain that pertains to the missing foot remains electrically activated, the individual may “feel” or “perceive” pain in the missing body area. This specific condition, phantom limb pain, is a classic illustration of a central pain syndrome. Signifying the pain is generated centrally in the human brain instead of peripherally in the foot. Because the pain is centrally generated in the brain and in this illustration the patient no longer even has a left foot, it is very difficult to relieve the signs and symptoms the person feels in the lost body part. There can be other forms of central pain syndromes which frequently develop after spinal-cord trauma, multiple sclerosis and stroke. They can produce terrible symptoms which are generated centrally and similar to the symptoms observed in phantom limb pain they are notoriously challenging to treat. Patients being affected by central pain syndromes frequently are dependent on pain medications and even with excessive amounts of these prescription drugs their pain is almost never satisfactorily managed. This situation contributes to a miserable existence and very poor quality of life.
That is the bad news, but there is certainly some promising news for the poor souls who are afflicted by central pain syndromes. A number of the mechanisms in the brain that bring about the development of central pain syndromes are now being uncovered and with this new information a number of unique treatments are appearing.
For quite a while brain investigators have known about a circuit in the brain referred to as the thermosensory pathway. The thermosensory circuit is an elaborate relay which allows sensations from the body (heat, cold, pain, light touch, itch, etc) to ascend from the periphery of the body, like the feet and hands, up to the brain for interpretation. This circuit is thought to be necessary for survival. If you think about this for a moment, it is essential to your health and survival for you to understand in cases where you might be too hot, too cold or if your skin is being injured by a stone in your shoe. Whenever your brain interprets this you can take appropriate actions like cool down when you are over heated, bundling up when you’re cold, and getting rid of the material out of your shoe well before it drills a hole in the underside of your foot.
Of all of the distinct recognized feelings, cold is apparently the most crucial when it pertains to the central pain syndrome. For some as yet unidentified reason, in the brain cold-awareness stops pain perception. So in the brain while you feel cold, you experience a lesser amount of discomfort and pain.
Often in central pain syndromes, that portion or component of the nervous system that is responsible for carrying cold sensations to the brain is damaged. This is often from injury to the tracts of nerves that carry cold feelings in the spinal-cord or higher areas of this pathway situated in the brain. The exact location where the cold sensations become obstructed isn’t as critical as the fact that the capability to perceive cold at the brain level has been decreased.
Since as we have just mentioned, cold perception inhibits pain perception, removing the ability to sense cold within the brain means pain perception will be able to run wild.
Let’s think about a bathtub as a possible example to demonstrate this principle. Assuming you have a pair of faucets pouring water into the tub, one cold another warm, you’ll have a quite pleasing bath. However think what would happen if the cold water was quickly turned off. After some time the bath water would become really hot. Eventually it would become scalding hot, intolerable!
This is simple illustration of what brain researcher believe happens in the brain when its ability to feel cold is lost in central pain syndromes. When the capacity feel cold is lost as a consequence of injury or illness in the thermosensory pathway, pain is perceived.
This is referred to as the thermosensory model of central pain.
This model can be use to identify and frequently effectively take care of central pain syndromes that don’t respond to the majority of customary pain control practices.
The usual patient is one which includes a history of a brain or spinal-cord trauma or disease. Pain is related to some insult of the central nervous system. The discomfort is often unrelenting and reacts inadequately to ordinary pain killing approaches.
The painful area will have a distinctive quality. Upon the application of ice to the painful body part the affected person will report either 1. only the sensation of the ice bag coming in contact with the body, without any feeling of cold or 2. severe burning sensation as opposed to cold appreciation in the painful area.
Often, until directly examined for the ability to feel cold in the painful area, the patient will be unaware that he or she is not able to sense cold in the painful body part. The fact is that many health professionals too often forget to check for the patient’s ability to experience cold in the affected body part. So the central nature of the pain syndrome often goes undetected.
It is this decrease in the ability to feel cold that opens the flood gates to pain perception in the brain and triggers the central pain syndrome.
Fortunately, neuroscientists have developed some techniques to reestablish the cold inhibition of pain sensation that is damaged or lost in the brain of individuals enduring central pain syndrome. We will explore therapy of the central pain syndrome in part two of this document.