Lay Summary: Body perception disturbances in Complex Regional Pain Syndrome

Dr Jenny Lewis, PhD, MSc, Dip COT
Clinical Research Occupational Therapist, The Royal National Hospital for Rheumatic Diseases, Bath UK

People with Complex Regional Pain Syndrome often describe altered thoughts, perceptions and feelings about their affected limb, known as body perception disturbances.  These thoughts and feelings include a repulsion and dislike of the limb, a sense that some how it feels alien and does not belong. In extreme cases some have an ongoing desire to get rid of the limb despite being advised against it by the doctors.

Many express that what they see when looking at their affected limb is often at odds with how the limb feels. Typically the affected limb is perceived by the individual as being much larger than it actually is, it feels burning hot yet to touch it is cool and it is much heavier than in reality.

Individuals commonly report a difficulty in knowing where their affected limb is physically positioned despite a heightened awareness due to pain. They describe holding their limb in what feels to be a normal and more comfortable position but are unaware that it is actually abnormal until others draw their attention to it.

Recent evidence suggests that body perception disturbance is becoming an increasingly recognised characteristic of CRPS with up to 84% expressing one or more of these features. Furthermore those with body perception disturbances often have greater difficulty in engaging with their affected limb which can affect rehabilitation outcomes.

In our experience of treating patients with CRPS at Bath in the UK, a greater understanding by health professionals of these seemingly bizarre features can improve communication between the patient and their practitioner, build trust and confidence in the patient of their clinical team, and allay unnecessary fears of “going nuts” that patients commonly express when discussing these symptoms.

Given that these features are not as apparent as others seen in CRPS such as pain and swelling, they are often missed by clinicians. By better understanding body perception disturbances clinicians can appropriately   assess the nature and extent of them which will inform approaches for treatment.

Our clinical research found that those that had longstanding CRPS had greater body perception disturbances, as did those in greater pain.  We also found that those with more extensive body perception disturbances had poorer touch perception. The knowledge of this relationship between body perception and touch perception gives us clues about what might be happening in the brain, as some of these processes occur in the same brain region.

Interestingly, although people with upper limb CRPS perceived that their affected hand was different in size to their non affected hand, when measured there was no difference in size between the two hands. This provides objective evidence that individuals’ perception of the size of their affected limb is at odds with reality and is a clear feature of the condition.  

When asked to close their eyes the mental picture that the patient sees in their minds eye of the affected limb is often misshapen and distorted. We believe that the representation of the affected limb within the brain is faulty which influences these thoughts and feelings and perceptions.

The second part of our research used brain imaging techniques (functional magnetic resonance imaging) to explore whether this was true by seeing whether there is a relationship between body perception disturbances and known changes in the brain.

The brain imaging data from this study is currently being analysed and we’ll keep you updated when we have the results.

By gaining a better understanding of the clinical features and brain alterations associated with body perception disturbances it will help us to know how to more appropriately treat them so people can perceive their affected limb as being more normal once more contributing to improved function and wellbeing.

October 28, 2010