We know that recovery from Complex Regional Pain Syndrome (CRPS) is variable: whilst some people make a relatively full recovery in a few months, others are left with pain and symptoms that persist for years [2]. What factors might influence this recovery process? Current theories argue that in a way, CRPS can be viewed as an overprotective response, where for some reason the brain perceives that the body’s tissues are under threat, and engages the body’s defence mechanisms [3]. These mechanisms include activating the sympathetic nervous system, the immune system, and increasing the person’s sensitivity to pain. In addition, it’s not surprising that people with CRPS often try to protect their limb by avoiding painful activities. Interestingly, whilst lots of research has looked at the physiological aspects of this “threat response”, not much research has looked at the psychological factors or state of mind that might contribute to it. This is surprising, as for many other pain conditions, theory and research suggest that pain-related fear, pain-catastrophizing (thinking the worst) and avoidance of movement all influence people’s pain experience [5].
We recently did a study designed to investigate whether thoughts, beliefs and emotions are associated with the extent to which people with CRPS recover in the first 12 months of their condition [1]. We recruited 66 CRPS patients within the first 3 months of developing CRPS symptoms, and assessed them straight away, then at 6 months and 12 months after their CRPS began. Each time, we measured their signs and symptoms of CRPS, their pain, level of disability, and various thoughts, beliefs and emotions that might be associated with a threat response. These included questionnaires about stress, anxiety and depression, pain catastrophizing, fear of pain/movement/re-injury, and the person’s thoughts and feelings about their painful limb (which we measured using a neat scale called the Bath CRPS Body Perception Disturbance Scale).
We looked to see if any of the thoughts, beliefs and emotions on the first visit predicted the subsequent outcomes over the year. We looked at 3 outcome variables: pain intensity, levels of disability, and the number of symptoms/signs of CRPS each person was experiencing. What we found was that those who were more anxious and disabled at the start had greater levels of pain over the 12 months. Those who had more pain and who were more fearful of pain/movement were more disabled over the year. And females, those who had more pain and who were more disabled at the start experienced a greater number of CRPS signs and symptoms over the 12 months.
What this suggested to us was that people whose state of mind makes them more likely to perceive threat (i.e. those who are more anxious and fearful of pain/movement) might experience a poorer recovery from CRPS. It is possible that this could operate in a bit of a vicious cycle, with those whose pain is severe experiencing more anxiety, which could in turn exacerbate the pain. Keep in mind that when we talk about anxiety and pain-related fear we don’t mean anything terribly abnormal – such feelings are a common response to health problems. We know that anxiety and fear influence the activity of the sympathetic nervous system, immune system, the body’s endogenous ability to modulate pain, and of course change a person’s behaviour, so there are lots of possible mechanisms by which anxiety and fear could influence pain in CRPS.
Additionally, those CRPS patients who were more disabled by pain at the start had a poorer recovery. We wondered if this might be an effect of immobilization: lots of the patients were given splints or braces or had their limb put in plaster, and it’s likely that these people would rate themselves as more disabled. Immobilizing a limb, even for a short time, has been shown to lead to lots of symptoms that feature in CRPS [4], so this is something that would also be worth investigating in future studies. Finally, and not surprisingly, we found that having greater pain from the outset was associated with poorer outcomes for people. Hopefully this will further encourage clinicians to be proactive with providing pain relief for people with new cases of CRPS, whenever these treatments are beneficial.
The next step for the field of research would be to see if it’s possible to reduce people’s levels of anxiety, fear, and disability and manage their pain better in the early stages of CRPS and see if this has any meaningful long term benefit.
About Debbie Bean
Debbie Bean is a Health Psychologist at The Auckland Regional Pain Service (TARPS) and has recently completed her PhD at The University of Auckland, looking at recovery from Complex Regional Pain Syndrome.
References
[1] Bean DJ, Johnson MH, Heiss-Dunlop W, Lee AC, Kydd RR. Do psychological factors influence recovery from complex regional pain syndrome type-1? A prospective study. Pain 2015;E-pub ahead of print.
[2] Bean DJ, Johnson MH, Kydd RR. The outcome of complex regional pain syndrome type 1: A systematic review. J Pain 2014;15:677-690.
[3] Moseley GL. Reconceptualising pain according to modern pain science. Phys Ther Rev 2007;12:169-178.
[4] Pepper A, Li W, Kingery WS, Angst MS, Curtin CM, Clark JD. Changes resembling complex regional pain syndrome following surgery and immobilization. J Pain 2013;14:516-524.
[5] Wertli MM, Rasmussen-Barr E, Weiser S, Bachmann LM, Brunner F. The role of fear avoidance beliefs as a prognostic factor for outcome in patients with nonspecific low back pain: A systematic review. Spine J 2014;14:816-836.e814.