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What is CRPS?
that the ischemia that occurs Lifting the veil
CRPS generally occurs after a when the blood flow to living tis- fracture, sprain or soft tissue dam- sue is stopped for a few or more on complex
age to an arm or leg. "In the days hours, and the reperfusion that following the injury, the limb follows when the blood re-enters begins to swell and the skin gets the tissue, may trigger the syndrome. His recent experiments Sufferers experience intense pain on rats confirm this hypothesis. s y n d r o m e
and become hypersensitive totouch. This first phase can last In their laboratories, the teams What could be simpler for a sea - weeks, months or even years," place tourniquets near the rats' soned physician than treating a explains Coderre. paws. For three hours, the blood simple wrist fracture? First, does not perfuse the area as realign and immobilize the bones In the second phase, patients normal. The tourniquets are then with a cast. Then, let nature take generally experience the opposite removed so that blood flow can its course. But for a small number condition. The affected area goes resume. "For approximately four of patients, the healing process is from being too warm to feeling weeks – a significant period of more difficult and turns into a abnormally cold, as if the person's time in the lifespan of a rat – nightmare. Days after their casts blood circulation was inhibited.
our animals suffered CRPS-like are applied, they begin experienc - But the pain remains constant. symptoms," reveals Coderre.
ing debilitating swelling that anti- Now all that was left to do was inflammatory drugs cannot effec - "In certain cases, a neurological explain why.
tively relieve. Even once their examination will reveal nerve bones have healed, patients con - lesions," says Professor Coderre.
The root of the pain
tinue to suffer severe pain. Barely "That's what's known as type-2 "During the period of ischemia, touching their skin can trigger a CRPS (formerly known as causal- oxidase enzymes collect in the tis- burning sensation. gia). In other cases, there are sues to which no blood flows. In no nerve lesions. That's type-1 and of itself, the phenomenon isn't The symptoms are unmistakable: CRPS (formerly known as reflex too harmful. If you are in a car complex regional pain syndrome sympathetic dystrophy)." Scien- accident, for example, and one of (CRPS) – a little-known but dev- tists have since discovered that your limbs gets pinned in the astating affliction that Te r e n c e both types may actually be one wreckage for several hours, the Coderre is trying to better under- and the same syndrome. tissue that lacks blood won't suf- stand. A professor in McGill fer too much damage…until Why an animal model?
you're freed," explains the profes- Anesthesia and member of the For years, the physiological dis- Quebec Pain Research Network turbances at the root of CRPS (QPRN), Coderre has developed have been the subject of debate in Reperfusion is what complicates a rat model that suffers from the scientific community. The matters. When in contact with the symptoms similar to those of McGill team believes that it has oxidase enzymes that have been CRPS. This unique rodent model finally found the key. Te r e n c e accumulating in the tissues, the is helping to lift the veil on the Coderre, along with his colleague oxygen that returns with the mysterious syndrome. Professor Gary Bennett and their blood is chemically reduced and research teams, has determined transformed into free radicals.
These free radicals are harmful to CRPS patients have a similar Trental™ or Cialis™) that in- the endothelial cells lining the poor oxygen supply in their mus- crease the ability of oxygen filled blood vessels and damage the cles that may underlie their pain.
red blood cells to penetrate microvessels. "Blood plasma Using a new device that uses through clogged microvessels.
seeping out of the injured vessels infrared light to study the level of causes swelling, and an over- blood oxygen in deep tissue, they Terence Coderre's team carried shoot of the returning blood are seeing that CRPS patients out experiments on rats with causes redness and warmth," he have reduced levels of oxygen topical creams that contain both within the muscles of their affect- nitric oxide donours and phos- phodiesterase inhibitors. The The swelling causes a further tests were conclusive and the constriction of blood vessels and researchers have since filed a additional ischemia that promotes Professor Coderre asserts that patent application for the use of further microvessel injury. With patients have several options. "In these combination creams in time, the damaged blood vessels Holland, people who suffer CRPS. "The advantage of a are no longer able to dilate fractures are given antioxidants cream rather than a pill is that such as vitamin C to prevent there is a reduced chance of side CRPS. This seems to reduce the effects," he explains. "The cream second phase of the syndrome, in risks because the antioxidants acts locally and has much fewer which the patient's skin becomes eff e c t s on the cardiovascular system." A futureaim will be to per- To compensate, the form clinical trials white blood cells invade the area. "The problem is that the CRPS patients.
narrow micro-bloodvessels are damaged "The support that and the white blood cells are fairly large and block the blood f l o w. The oxygen transfer to the tissue does not occur nor- cherche en santé mally," continues the du Québec (FRSQ) Andrea Cormier was a determining curb the effect of the oxygen free factor in our progress," affirms But what triggers the pain? "Think radicals that accumulate in the tis- Terence Coderre. "Our research of when you're jogging and you sue during reperfusion," he says.
lies somewhere between cardio- start to cramp up. You're suffering According to the researcher, vascular science and the neuro- because there isn't enough antioxidants could be effective sciences, and that sometimes oxygen getting to the tissue and for prevention and in patients who complicates things when we lactic acid is building up in your have already developed the apply for funding. Fortunately, the muscles. CRPS sufferers experi- FRSQ's integrated vision to fur- ence this inadequate muscle ther health science research sup- oxygenation constantly, some- Administering drugs that increase ports our approach." times for years," he explains.
nitric oxide may also provide relieffor patients, since the vasodilator Based on the results of the animal relaxes the blood vessels and experiments, Professor Coderre helps blood flow. Sufferers may and his colleagues have begun also benefit from drugs such as studies to determine whether phosphodiesterase inhibitors (like The QPRN is one of the Research Writer: Dominique Forget Networks funded by the Design: Solutions Ink

Source: http://qprn.ca/newsletters/EN/QPRN%20Research%20Corner%20March%202010.pdf