Medical > Research

Project Abstract and Lay Summary

A study to investigate the relationship between body perception disturbances and cortical representation of the affected limb in complex regional pain syndrome

Jenny Lewis, PhD, MSc, Dip COT
Recipient of the 2008-2009 Tobias Young Investigator Research Award

Rationale

Pain in a limb is the primary feature of Complex Regional Pain Syndrome (CRPS)¹ One could assume therefore that people with CRPS might be over attentive, wishing to protect or look after their affected limb. However, both clinical observations and recent literature suggest that this is not the case. Those with CRPS have a distorted perception of that limb such that many express strong feelings of disassociation and hate about the affected limb and some have a desperate desire to amputate it.^2,3,4,5 When asked to generate a mental image of the affected part with their eyes closed, many describe distorted mental pictures of that limb such that anatomical sections are missing.³ The reported prevalence of these disturbances in body perception is high.^2,6 Furthermore, those presenting clinically with these altered perceptions have difficulty in engaging with their affected limb, which can be detrimental to rehabilitation. Recent brain imaging studies have shown altered neural activity within brain regions representing the CRPS limb.^7,8,9,10 We propose that these changes in the way the brain represents the affected limb are associated with body perception disturbances described by those with CRPS.

Objective
The overall objective of this research is to establish whether there is a relationship between clinical descriptions of body perception disturbances expressed by patients with CRPS and neural changes in the somatosensory cortices, a brain region responsible for touch sensation.

Methods

Functional magnetic resonance imaging, a method that measures changes in blood flow within the brain, will be used to explore changes in the somatosensory cortical representation of the CRPS index finger when electrically stimulated with a non painful stimuli in 20 patients with upper limb CRPS. These images will be compared to their unaffected finger and data from 20 age and gender matched healthy control volunteers.

To measure the presence, nature and extent of disturbances in body perception, prior to brain imaging, those with CRPS will be asked to rate various aspects and describe a mental image of their affected limb via the body perception disturbance scale (see appendix 1 in research plan). To determine the degree of clinical presentation, objective signs of swelling and touch sensation of the affected hand will be measured. Statistical analysis will be undertaken between the imaging and body perception disturbance findings to establish whether a correlation between the two exists.

Significance of research
This research is important in two key respects. Firstly, it aims to improve our understanding of CRPS. Objective evidence of an association between the brains representation of the CRPS limb and disturbances in body perception may provide valuable insights into the central mechanisms that are responsible for altered thoughts and feelings about the affected limb. Secondly, it may help in treatment. Given that CRPS is known to be resistive to conventional treatments, an improved understanding of body perception mechanisms may identify areas in which rehabilitation interventions could be specifically targeted.
In conclusion, a better understanding of this relationship will inform and contribute to improving rehabilitation outcomes for patients with CRPS.

1 Scadding J., 1999 Textbook of Pain, 835-849
2 Forderreuther, S., Sailer, U., & Straube, A. 2004, Pain, vol. 110(3) 756-761.
3 Lewis, J. S. et al. 2007, Pain, vol. 133(1-3) 111-119.
4 Moseley, L. 2005, Neurology, vol. 65(1) 773
5 Galer, B. S., Butler, S., & Jensen, M. P. 1995, J Pain Symptom Manage. vol.10(5) 385-391
6 Galer, B. S. & Jensen, M. 1999, J Pain Symptom Manage. vol. 18(3) 213-217
7 Maihofner, C., et al. 2003, Neurology, vol. 61(12) 1707-1715.
8 Maihofner, C., et al. 2004, Neurology, vol. 63(4) 693-701.
9 Maihofner, C., et al. 2007, Brain, vol. 130, 2671-2687.
10 Pleger, B., et al. 2005, Annals of Neurology, vol. 57(3) 425-429.

Jenny Lewis PhD, MSc, Dip COT
Clinical Research Occupational Therapist
The Royal National Hospital For Rheumatic Diseases
Upper Borough Walls
Bath
BA1 1RL
UK

Added December 22, 2008