An embarrassment of pain perceptions? Towards an understanding of and explanation for the clinical presentation of CRPS type 1.

Complex regional pain syndrome (CRPS), a fairly common problem in rheumatological and orthopaedic practice, is an allodynic pain state of uncertain pathology often variably and unpredictably responsive to treatments. Although published diagnostic criteria are available, in the reality of clinical practice these do not appear to encompass the wide variety of symptoms that a patient may present with. This leads to scepticism on the part of the clinician and confusion for the sufferer. This article aims to provide some explanations for an often bewildering clinical picture. We provide a construct for the plethora of symptoms that we have entitled 'the embarrassment of pain perceptions'. With the aid of a case report we examine recent research that suggests how peripherally based symptoms and signs arise from changes within the central nervous system, with particular attention given to the control function of the motor-proprioceptive integrative system. We speculate how these changes within the central nervous system may provide the patient with CRPS the ability to access complex layers of lower level perceptions that are normally suppressed. We propose that such a system may explain some of the clinical puzzlements seen in this condition and suggest that the complexities of CRPS may provide an insight into brain development through evolution, which is a fruitful area for interdisciplinary clinical and scientific research.