HAS Research Blog


Just showing posts from March 2011

Understanding chronic pain: an interview with Professor Candy McCabe 

Posted by Kathleen Steeden | 13 comments

It’s hard for most of us to imagine living with pain that doesn’t have a physical explanation. For medical professionals it can present a massive challenge: how can you diagnose a condition or advise treatment for a patient suffering from persistent pain with no obvious cause? Professor Candy McCabe is a UWE researcher and Consultant Nurse at the Royal National Hospital for Rheumatic Diseases, Bath, who is working to understand these chronic pain conditions and develop therapies to provide relief to sufferers.

Prof Candy McCabeProfessor McCabe’s research is supported by an NIHR (National Institute for Health Research) Career Development Fellowship for five years, which will fund a series of projects focused on understanding the roles of the motor and sensory systems in the perpetuation, exacerbation and relief of chronic pain. I met with her to discuss her research ahead of her inaugural lecture at UWE in April.

How did you become interested in researching pain?
I have worked at the Royal National Hospital since ’96 and am still based there two days a week. I started as a research nurse in Rheumatology and conducted my MSc exploring pain in rheumatoid arthritis where patients had perceived joint swelling but no physical sign of it. The ‘phantom swelling’ we found in this population led me into the phantom limb literature and I started to look at those with Complex Regional Pain Syndrome. We started a research clinic in 2000 and I began my PhD in 2001. The research clinic grew into a national service for patients with CRPS and is now the leading UK centre for this condition.

What did your PhD research focus on?
It focused on complex regional pain syndrome [CRPS], which is a condition that causes severe, continuous pain, usually affecting an arm or a leg. For example right after a minor fracture a sufferer might almost immediately start to complain that the limb hurts far more than would be expected for the injury sustained. If they have a plaster cast it’s quite common for sufferers to complain that it’s too tight even if the medical professional thinks that it’s fitted correctly. The limb sometimes appears hot and sweaty, perhaps with changes of colour or skin texture, the hair might have grown very thick and the nails unusually quickly. Approximately 80% of people with these symptoms will just recover, but there’s that small percentage of people who develop chronic problems so it’s important that this is diagnosed early.

It sounds really scary…
It’s a source of extreme stress. People complain that they feel that their arm is a completely different size and shape, or that there are parts missing. Some patients even say that they want to cut off their own arm, they hate it so much.

Are these patients often dismissed by their GPs?
Actually, often their GPs are their biggest champions but they are frequently dismissed after being referred to a number of specialists for x-rays and MRIs which come back with normal results.

What testing methods did you use to understand the research participants’ symptoms if there were limited physical signifiers?
We started by collecting detailed clinical descriptions of their pain. We quite often looked at the literature about other complaints in order to understand the mechanisms at work. Some of the descriptions were very similar to rheumatoid arthritis and phantom limb pain (a condition where an amputee continues to feel sensations or pain in their missing limb).

During my PhD research I found that when you touched the painful limb of someone with CRPS they could sometimes feel the same sensation in other areas of their body. For example, if you touched their painful hand they would feel exactly the same sensation on their face, even though this area was not painful. Amputees had also exhibited some of these symptoms. These misplaced feelings are called referred sensations and they are a clinical representation of the changes that take place within the sensory maps in the brain. There are similar changes that occur in the motor maps and my research has been focused on gaining a better understanding of how these changes in sensory input and motor planning, may relate to pain.

What treatment options did you start to look at to resolve this ‘cross-wiring’ problem?
We looked at mirror visual feedback that had been shown to help relieve phantom limb pain. A person sits either side of a mirror with their unaffected limb reflected, and exercises both limbs together, viewing the reflection of the healthy limb in the mirror. This illusion gives the patient an image of a normal, unaffected limb in the felt position of their actual affected limb. So we provide corrective sensory feedback.

Did it work?
It did work remarkably well; especially for patients displaying early symptoms. We also tested whether we could trigger pain and other sensory changes in healthy subjects using mirrors by generating a mismatch between sensory input and motor output. We positioned subjects with their limbs either side of a mirror and they moved their arms in different direction whilst looking at the reflection that showed them moving in the same direction. This generated all kinds of changes in the limb hidden behind the mirror, even after just 20 seconds. Some subjects perceived altered weight and temperature of the limb. For some people they felt they had ‘amputated’  the limb they couldn’t see and others felt that they had an extra arm. In a small percentage of people it also caused pins and needles or an unpleasant sensation that was strong enough that they didn’t want to continue with the study.

Did your research reveal anything about who is more likely to be affected?
We found that some people were particularly vulnerable to this and others were very tolerant. It does suggest that some people are predisposed to these conditions. We were interested to see if people with other chronic pain conditions may also perform poorly on this task. Fibromyalgia is another chronic illness that can cause pain and clumsiness and poor body perception. It’s thought that fibromyalgia might also be caused by an underlying motor/sensory discrepancy and as we predicted these patients did worse on the mismatching mirror test.

It sounds like many of these painful conditions are related?
CRPS is the model condtion we have used to explore chronic pain but the mechanisms are the same for a number of other conditions that present as persistent neuropathic pain. They can affect any part of the body and people have experienced identical symptoms in the face, the back, even the internal organs such as the bladder.

Does that mean that treatment options are the same? What are the new treatment options you are developing?
The new therapies we have been developing for CRPS are informed from what we know about other pain conditions. These new therapies include mirror visual feedback, electrical sensory discrimination—where you pass stimulus through four pairs of electrodes placed on the affected part of the body and the patient has to focus on the sensory information to identify which pair it being stimulated, and motor planning using imagined movements.

Is there more support available for CRPS sufferers now than when you started your research?
We have established a national specialist network for research/health professionals and a CRPS-UK register, which is run for us by the University of Southampton. This Network and Register help us to conduct multi-centre studies into CRPS and follow cohorts of patients over time. We are just starting to conduct these studies with our European collaborators and this will help greatly with larger clinical studies. We also provide training for health professionals, helping them to identify CRPS early on in the condition and consider novel treatment methods.

I imagine it could be quite distressing to work with people who live in constant unexplained pain. Do you have good feedback from patients and research subjects?
Oh yes, we do get excellent feedback. From a service perspective our patients love that there’s a group of people who understand them, who don’t try to touch their limb, which is the impulse of most healthcare workers trying to diagnose pain. And we will directly ask questions such as whether they feel like they want to cut off the limb. Patients are often very distressed by these feelings but frightened of telling healthcare professionals about it as they fear they will be thought of as mad.

It must be such a challenge for others to understand how it feels to suffer with CRPS?
Yes and I’m working with Dr Ailie Turton (Department of Nursing and Midwifery), Professor Nichola Rumsey (Centre for Appearance Research), Dr Mark Palmer (Department of Computer Sciences and Creative Technologies), and Dr Jenny Lewis (from the Royal National Hospital for Rheumatic Diseases), on a project that could help. Mark has helped us to develop software that uses an avatar of a person that can be manipulated by a CRPS sufferer to visually depict what their limb feels like to them. They can make all sorts of changes—changes in size, colour, texture, they can even visually represent the temperature of their limb.

An example of the avatar developed as part of the HEAT funded project 'Development and evaluation of a tool for assessing body image'. A sufferer of Complex Regional Pain Syndrome can manipulate the image to show changes in the feelings of the size, temperature, skin texture, etc of their affected limb.

It must be comforting for patients that somebody is willing to listen and accept their symptoms?
And quite often that is the most therapeutic thing for people I think; just for someone to listen to them, to believe them, and to offer an explanation for the way they’re feeling.

For more information contact Professor Candy McCabe

Dr Chris Alford 'In the house' on BBC Radio Bristol 

Posted by Kathleen Steeden | 0 comments

Alarm clockDr Chris Alford was ‘Dr in the House’ on BBC Radio Bristol's Saturday Surgery on Saturday 12 March 2011.  He discussed sleep problems and disorders with presenter Dr Phil Hammond, as well as his sleep research at UWE and in the Southwest. Chris and Phil also responded to listener’s questions on sleep related matters.

For more information contact Dr Chris Alford

UK/China workshop: Innovative Technologies for the Food Industry, 21 - 22 July 

Posted by Kathleen Steeden | 0 comments


UWE is hosting a 2-day workshop on Innovative Technologies for the Food Industry organised by the Centre for Research in Biosciences, the Institute of Bio-Sensing Technology, the Chinese Academy of Agricultural Sciences and the China Agricultural University.

As  part of a BBSRC China partnering award, this workshop aims to bring together the UK and Chinese academia, industry, policymakers and other stakeholders in order to combine effort in addressing important issues of development, evaluation and taking to international market novel and rapid technologies for the food industry. Particular emphasis will be placed on cost-effective technologies for the detection of environmental pollutants in animal feed and animal-derived food.

The workshop will include presentations, poster sessions, industry exhibition and group discussions. There will be opportunity for networking, developing project ideas, exploring funding opportunities and discussing long-term collaboration between UK and Chinese academia and industry.

Click here for more information and to register