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Complex but not crazy

Published on 15 November 2010
Source: Arthritis Today

Dr Helen Cohen

For years people with complex regional pain syndrome suffered such bizarre symptoms they were often labelled “mad”. New research has now shed new light on the role of the brain, offering real hope for the future.

For most healthy people the images below, the cube and the duck/rabbit, cause them some mild visual confusion. Do they focus on the front or the back of the cube? Is it a duck or a rabbit? For most of us, the images “flip” from one to the other between eight and 20 times a minute.

However, for people suffering from complex regional pain syndrome (CRPS), the seemingly innocuous cube and duck/rabbit images are more confusing – and disturbing. When shown these images, 64 per cent of a group of people with this condition found their pain got worse within seconds of looking at them. Most of them had to shut their eyes or turn away because the pain got so acute.
Cube art

Other weird things happened. Thirty two per cent of the group had a bizarre response in terms of blood flow when looking at the images – in one arm their blood flow went up, and in the other arm it went down – which is unheard of. And 40 per cent of the group described the cube as “flipping” so many times a minute that they couldn’t count it. Some people also had muscle spasms and sweating. However, groups of people with osteoarthritis and rheumatoid arthritis reported absolutely no difference in their pain levels when exposed to the same images.

Duck or rabbit?Dr Helen Cohen has spent the past three years investigating how CRPS can both affect and be affected by reflexes controlling blood flow and sweating, and by sensations such as touch and vision, as part of an Arthritis Research UK clinical research fellowship.

The work described here was just one of several strands of research that she conducted with CRPS patients at the Royal National Hospital for Rheumatic Diseases (RNHRD) in Bath, and if anything, she says, it proves that patients with CRPS are not mad. Instead the pattern of the changes suggests that the way the brain switches on stress responses has changed in patients with CRPS.

“Until now this sort of behaviour among CRPS patients has been written off as craziness, but I have shown that something odd is going on here; that pain networks are involved in switching different areas of the brain that we do not fully understand,” she says.

“There is a basis here for what would otherwise be called madness. Our previous research had shown that patients’ pain can be relieved by performing a series of exercises in front of a mirror, with more than half of people experiencing pain relief during and afterwards. Now we know that something as simple as an optical illusion such as the cube or the duck/rabbit, which causes a pure conflict in visual information, can switch on severe worsening of pain.”

'Until now this sort of behaviour has been written off as craziness'

Dr Cohen’s research started when members of the CRPS team began to listen to patients’ stories about their bizarre symptoms. Patients told her that if they looked at objects in the distance they seemed to move; stable objects jumped about and words in a book moved around the page, making it difficult to focus. So instead of dismissing them as crazy stories she began to investigate, involving 55 patients with CRPS and 40 healthy volunteers and 80 patients with osteoarthritis and rheumatoid arthritis to act as controls.

Dr Helen Cohen

As well as looking at the effects of optical illusions on people with CRPS she also ran a series of tests to check the functioning of the parietal lobe of the brain, a particular area involved with integrating sensory functions such as auditory, visual and touch information. It can be affected when a person suffers a stroke, and cause apparently bizarre symptoms such as ignoring one side of the body completely, and difficulty using language and numbers.

She gave the patients ten different, simple tests involving letters, numbers, identifying objects with their eyes closed, copying and drawing, and so on. The results, says Helen Cohen, were “amazing.”

“In my cohort of 22 people, 62 per cent failed in one category or more. Asked to draw a square they drew a circle, asked to draw a house as drawn by a child they drew it upside down, a round clock-face was square with the numbers upside down and back to front. This was all done with extreme concentration, and when they looked at what they had drawn, they thought they had done it right and were very surprised.”

She then asked the CRPS patients if they had ever done anything similar at home. The answers were unequivocal. “Many of them had problems with cheques – they were always being returned because they had written numbers wrong, they often rang the wrong numbers of mobile phones, and got their debit cards swallowed up by cash dispensers because they kept getting the PIN numbers wrong,” says Dr Cohen. “Prior to them developing CRPS this never happened. We found parietal lobe dysfunction in significant numbers of CRPS patients, which is not apparent in standard neurological examination.”

So can this knowledge, fascinating as it is, be used to improve the treatment of people with CRPS, which is currently largely ineffective?

Dr Cohen acknowledges the need for further research, and in the use of high tech imaging and scanners to find out more about what is going on in the brains of CRPS patients. Meanwhile she is hopeful that rehabilitation approaches used to “re-train” the brains of stroke patients may be effective, and is planning to set up a new CRPS clinic at the Royal National Orthopaedic Hospital in Stanmore, Middlesex, where she now works as a full-time clinician.

“I think the most exciting thing about this research is that it’s a start in understanding a little-understood condition, and goes a long way to describing the bizarre symptoms and sheer complexity of the brain/pain networks which we haven’t understood before,” concludes Helen Cohen. “This will help us to approach our rehab and treatment more effectively. And it is lovely to be able to say to patients: ‘Yes, I believe you, and you can believe it yourself now, you are not going mad, there is something on going here,’ which reassures them tremendously.”

Cath Taylor took part in the study. Read Cath's story about living with CRPS.

What is complex regional pain syndrome?

Complex regional pain syndrome (CRPS), formerly known as reflex sympathetic dystrophy (RSD), is a rare but severe type of rheumatic diseases which causes excruciating limb pain for sufferers and often, but not always, develops after a minor injury. It also leads to temperature changes, sweating and swelling, and in extreme cases the affected limb has to be amputated. Even lightly brushing the skin can trigger extreme pain, in a process known as allodynia.

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