Candida S. McCabe

Sensorimotor Incongruence and Body Perception: An Experimental Investigation

Objectives: Several studies have shown that mirrored arm or leg movements can induce altered body sensations. This includes the alleviation of chronic pain using congruent mirror feedback and the induction of abnormal sensation in healthy participants using incongruent mirror feedback. Prior research has identified neuronal and conceptual mechanisms of these phenomena. With the rising application of behavior-based methods for pain relief, a structured investigation of these reported effects seems necessary. Methods: We investigated a mirror setup that included congruent and incongruent hand and arm movements in 113 healthy participants and assessed the occurrence and intensity of unusual physical experiences such as pain, the sensation of missing or additional limbs, or changes in weight or temperature. A wooden surface instead of a mirror condition served as control. Results: As reported earlier, mirrored movements led to a variety of subjective reactions in both the congruent and incongruent movement condition, with the sensation of possessing a third limb being significantly more intense and frequent in the incongruent mirror condition. Reports of illusory pain were not more frequent during mirrored than during non-mirrored movements. Conclusion: These results suggest that, while all mirrored hand movements induce abnormal body perceptions, the experience of an extra limb is most pronounced in the incongruent mirror movement condition. The frequent sensation of having a third arm may be related to brain processes designed to integrate input from several senses in a meaningful manner. Painful sensations are not more frequent or intense when a mirror is present.

Enhanced pain and autonomic responses to ambiguous visual stimuli in chronic Complex Regional Pain Syndrome (CRPS) type I

Cortical reorganisation of sensory, motor and autonomic systems can lead to dysfunctional central integrative control. This may contribute to signs and symptoms of Complex Regional Pain Syndrome (CRPS), including pain. It has been hypothesised that central neuroplastic changes may cause afferent sensory feedback conflicts and produce pain. We investigated autonomic responses produced by ambiguous visual stimuli (AVS) in CRPS, and their relationship to pain. Thirty CRPS patients with upper limb involvement and 30 age and sex matched healthy controls had sympathetic autonomic function assessed using laser Doppler flowmetry of the finger pulp at baseline and while viewing a control figure or AVS. Compared to controls, there were diminished vasoconstrictor responses and a significant difference in the ratio of response between affected and unaffected limbs (symmetry ratio) to a deep breath and viewing AVS. While viewing visual stimuli, 33.5% of patients had asymmetric vasomotor responses and all healthy controls had a homologous symmetric pattern of response. Nineteen (61%) CRPS patients had enhanced pain within seconds of viewing the AVS. All the asymmetric vasomotor responses were in this group, and were not predictable from baseline autonomic function. Ten patients had accompanying dystonic reactions in their affected limb: 50% were in the asymmetric sub‐group. In conclusion, there is a group of CRPS patients that demonstrate abnormal pain networks interacting with central somatomotor and autonomic integrational pathways.

The impact of cortical remapping interventions on pain and disability in chronic low back pain: a systematic review.

BACKGROUND Cortical change, in the manner of cortical remapping is a common feature of and potential driver for chronic low back pain (CLBP). Novel interventions such as graded motor imagery (GMI) and mirror visual feedback (MVF) have been shown to facilitate correction of cortical changes and improve symptoms in other chronic pain states. However, little is known regarding the effectiveness of these treatment approaches in CLBP. OBJECTIVE To identify and assess the current evidence regarding the effectiveness of interventions which target cortical remapping in the management of CLBP. DATA SOURCES The electronic databases Medline, Embase, CINAHL, AMED, OVID, PEDro, BNI, PsycINFO, HMIC, and Cochrane library were systematically searched. STUDY SELECTION Of 11 potential citations identified, 5 articles were identified for inclusion and critiqued. These comprised 3 randomised controlled trials (RCTs), 1 randomised cross-over study, and 1 multiple case study design. RESULTS Visualisation of lumbar movement may significantly improve movement-related pain severity and duration. A combined sensorimotor retraining approach has been shown to produce short-term improvements in both pain and disability outcomes in CLBP. The relative effectiveness of individual interventions and their long-term efficacy have yet to be established. CONCLUSIONS There is a paucity of robust literature which has examined the application and efficacy of these novel treatments in the management of CLBP. Results from the few CLBP studies which are available are encouraging. Further, robust research is needed to optimise treatment protocols and establish their long-term effectiveness in CLBP.

Imaging and Clinical Evidence of Sensorimotor Problems in CRPS: Utilizing Novel Treatment Approaches

Inflammation and altered autonomic function are diagnostic signs and symptoms of Complex Regional Pain Syndrome. In the acute stages these are commonly at their most florid accompanied by severe pain and reduced function. Understandably this has directed research towards potential peripheral drivers for the causal mechanisms of this condition. In particular this is now focused on the inflammatory process and the potential role of autoantibodies. More subtle changes also occur in terms of altered tactile processing within the affected limb, disturbances in body perception and motor planning problems that become more evident as the condition progresses. Through careful clinical observation and neuro-imaging techniques, these changes are now thought to be associated with altered cortical processing that includes reorganisation of both the motor and sensory maps. Furthermore, there appears to be a close relationship between the intensity of pain experienced and the extent of cortical re-organisation. This increased knowledge around the peripheral and central mechanisms that may be operating in CRPS has been used to inform novel therapeutic approaches. We discuss here the presenting signs and symptoms of CRPS, with particular focus on sensory and motor changes and consider which mechanisms may drive these changes. Finally, we consider the emerging therapeutic options designed to correct these aberrant mechanisms.

Prolonged ketamine infusion as a therapy for complex regional pain syndrome: synergism with antagonism?

Complex regional pain syndrome (CRPS) remains a troubling and often refractory pain condition that typically develops either following injury to a peripheral nerve (type II) or following trauma without obvious peripheral nerve damage (type I). It presents with a characteristic constellation of sensory, motor, autonomic and vascular signs, within which pain is the central feature. Its aetiology is uncertain [1], and there is an ongoing debate about whether it is primarily a neuropathic or an inflammatory/autoimmune condition [2]. The existing data from treatment trials of conventional analgesics, antineuropathic pain medications or nerve blocks have been largely disappointing [3,4], and much of the emphasis in treatment is on functional rehabilitation (see the recent Royal College of Physicians treatment guidelines [5]). The limitations of existing treatments means that a substantial cohort of CRPS patients (∼15 000 new cases per year in the UK based on the incidence figures of de Mos et al. [6]) is left with refractory, long-term severe pain causing significant disability. Consequently, there is a need to develop innovative treatment approaches, such as graded motor imagery, mirror visual feedback, spinal cord stimulation and transcranial magnetic stimulation, all of which have shown some utility in clinical trials. Set within this context, the review of Niesters et al. [7] in this issue of BJCP is timely, and articulates the arguments for a role of prolonged ketamine infusion in the management of neuropathic pain and specifically for CRPS.

Coping with chronic complex regional pain syndrome: advice from patients for patients

Objective: To explore what advice people currently living with chronic complex regional pain syndrome would offer to another person coming to terms with a diagnosis of chronic complex regional pain syndrome. Methods: Semi-structured interviews with 21 adults (5 male) living with chronic complex regional pain syndrome who had completed a complex regional pain syndrome rehabilitation programme were conducted. Results: Effectively self-managing complex regional pain syndrome required individuals to play an active role. This could only be achieved if they felt they had sufficient control. Means of attaining control involved attaining a level of acceptance, becoming well-informed and accessing the right kind of support. The advice offered by patients for patients largely reflected that offered by healthcare professionals. One area where there was a conflict concerned sleep hygiene. Conclusions: Our study provides support both for the argument put forward by Redman that without appropriate preparation and support, self-management is ineffective, and that by Skuladottir and Hallsdottir that the main challenge of the chronic pain trajectory is that of retaining a sense of control. The clinical implications of this are discussed.

‘Now you see it, now you do not’: sensory–motor re-education in complex regional pain syndrome

The patient with complex regional pain syndrome (CRPS) commonly describes a lack of ownership of their painful limb, poor definition of that body part and difficulty with localization of the limb when performing daily activities. These descriptions suggest that sensory input from the limb may be reduced leading to neglect of the limb and poor motor control. However, the cardinal symptom of CRPS is pain, commonly severe, which demands a high level of attention. Patients are highly protective of the painful region and hypervigilant to any potential threats to their affected limb. These seemingly conflicting behavioural responses and sensory descriptions are confusing for the patient and health-care professional. In recent years our understanding has greatly advanced on how altered sensory perception of a CRPS affected limb relates to changes in the central representation of that body part, and how this may interact with motor planning and autonomic function. Excitingly, this increased knowledge has directly informed clinical practice via a new evaluation of sensory–motor re-education techniques and the development of novel interventions to enhance sensory discrimination. We review the common sensory problems seen in CRPS, the mechanisms that may be behind these clinical symptoms, and how sensory, motor and autonomic systems interact. Therapies designed to enhance sensory discrimination and motor planning are discussed, supported by the results of a small case series undergoing sensory re-education for CRPS. The clinical protocol and two case studies are available as additional online material to illustrate how all of this is applied in practice.

Establishing the characteristics for patients with chronic Complex Regional Pain Syndrome: the value of the CRPS-UK Registry

Objective: The long-term prognosis of patients with Complex Regional Pain Syndrome (CRPS) is unknown with no reported prospective studies from the United Kingdom longer than 18 months. The CRPS-UK Network aims to study this by use of a Registry. The aims of this article are, to outline the CRPS-UK Registry, assess the validity of the data and to describe the characteristics of a sample of the UK CRPS population. Methods: A web-based CRPS-UK Registry was developed and made accessible to centres experienced in diagnosing and managing patients with CRPS. Pragmatic annual follow-up questions were agreed. Results: Up until July 2013, the Registry has recruited 240 patients. A blinded, validation study of 20 consecutive patients from two centres (10 each) demonstrated 95.6% completion and 99.4% accuracy of a random sample of the recorded data. These patients had chronic disease (median duration: 29 months); 72.5% were female (2.6:1), with a mean age at symptoms onset of 43 years, and were left-handed more than expected (21.8% versus 10% in the general population). Patients reported a delayed diagnosis, with the median time between symptom onset and diagnosis of 6 months. In all, 30 patients (12.5%) had multiple limb involvement and (83.3%) had a contiguous spread of CRPS. Conclusion: CRPS-UK Registry is a validated method for actively recruiting well-characterised patients with CRPS to provide further information on the long-term outcome.

Recommendations for a first Core Outcome Measurement set for complex regional PAin syndrome Clinical sTudies (COMPACT)

Abstract Complex regional pain syndrome (CRPS) is a persistent pain condition that remains incompletely understood and challenging to treat. Historically, a wide range of different outcome measures have been used to capture the multidimensional nature of CRPS. This has been a significant limiting factor in the advancement of our understanding of the mechanisms and management of CRPS. In 2013, an international consortium of patients, clinicians, researchers, and industry representatives was established, to develop and agree on a minimum core set of standardised outcome measures for use in future CRPS clinical research, including but not limited to clinical trials within adult populations. The development of a core measurement set was informed through workshops and supplementary work, using an iterative consensus process. “What is the clinical presentation and course of CRPS, and what factors influence it?” was agreed as the most pertinent research question that our standardised set of patient-reported outcome measures should be selected to answer. The domains encompassing the key concepts necessary to answer the research question were agreed as follows: pain, disease severity, participation and physical function, emotional and psychological function, self-efficacy, catastrophizing, and patients global impression of change. The final core measurement set included the optimum generic or condition-specific patient-reported questionnaire outcome measures, which captured the essence of each domain, and 1 clinician-reported outcome measure to capture the degree of severity of CRPS. The next step is to test the feasibility and acceptability of collecting outcome measure data using the core measurement set in the CRPS population internationally.

Evaluation of a Prototype Tool for Communicating Body Perception Disturbances in Complex Regional Pain Syndrome

Patients with Complex Regional Pain Syndrome (CRPS) experience distressing changes in body perception. However representing body perception is a challenge. A digital media tool for communicating body perception disturbances was developed. A proof of concept study evaluating the acceptability of the application for patients to communicate their body perception is reported in this methods paper. Thirteen CRPS participants admitted to a 2-week inpatient rehabilitation program used the application in a consultation with a research nurse. Audio recordings were made of the process and a structured questionnaire was administered to capture experiences of using the tool. Participants produced powerful images of disturbances in their body perception. All reported the tool acceptable for communicating their body perception. Participants described the positive impact of now seeing an image they had previously only imagined and could now convey to others. The application has provided a novel way for communicating perceptions that are otherwise difficult to convey.