Imagined movements cause pain and swelling in a patient with complex regional pain syndrome

Virtual embodiment for improving range of motion in patients with movement-related shoulder pain: an experimental study

BACKGROUND

Recent evidence supports the use of immersive virtual reality (VR) as a means of delivering bodily illusions that may have therapeutic potential for the treatment of musculoskeletal conditions. We wanted to investigate whether a single session of an embodiment-based immersive VR training program influences pain-free range of motion in patients with shoulder pain.

METHODS

We designed a rehabilitation program based on developing ownership over a virtual body and then "exercising" the upper limb in immersive VR, while the real arm remains static. We then carried out a single-arm pre-post experiment in which 21 patients with movement-related musculoskeletal shoulder pain were exposed to the 15-min VR program and measured their active pain-free range of motion immediately before and afterwards.

RESULTS

We found that shoulder abduction and hand-behind-back movements, but not shoulder flexion, were significantly and clinically improved post-intervention and that the level of improvement correlated with the level of embodiment. Following this one session, at 1-week follow-up the improvements were not maintained.

CONCLUSIONS

Virtual embodiment may be a useful therapeutic tool to help improve range of motion in patients with movement-related shoulder pain in the short term, which in turn could expedite rehabilitation and recovery in these conditions.

Managing acute phantom limb pain with transcutaneous electrical nerve stimulation: a case report

INTRODUCTION

Phantom limb pain is characterized by painful sensations in the amputated limb. The clinical presentation of acute phantom limb pain may differ from that of patients with chronic phantom limb pain. The variation observed implies that acute phantom limb pain may be driven by peripheral mechanisms, indicating that therapies focused on the peripheral nervous system might be successful in reducing pain.

CASE PRESENTATION

A 36-year-old African male with acute phantom limb pain in the left lower limb, was treated with transcutaneous electrical nerve stimulation.

CONCLUSION

The assessment results of the presented case and the evidence on acute phantom limb pain mechanisms contribute to the current body of literature, indicating that acute phantom limb pain presents differently to chronic phantom limb pain. These findings emphasize the importance of testing treatments that target the peripheral mechanisms responsible for phantom limb pain in relevant individuals with acquired amputations.

Assessment of body perception disturbances in complex regional pain syndrome: A systematic review using the COSMIN guideline

OBJECTIVE

To conduct a systematic review to identify which tools are being used to assess body perception disturbances in Complex Regional Pain Syndrome (CRPS) and to provide an evidence-based recommendation in the selection of an assessment tool, based on measurement properties.

DATABASES AND DATA TREATMENT

Five electronic databases (EMBASE, Pubmed, PsycInfo, Science Direct and Web of Science) were searched for English or French written articles, with no time restrictions. All original articles using a body perception assessment tool with adult patients with CRPS were selected, regardless of their design (controlled trials, single case, qualitative study). Two investigators screened abstracts, selected full articles and extracted data independently.

RESULTS

Thirty-eight full-text papers were obtained and three main methods to evaluate body perception disturbances were identified: The Bath Body Perception Disturbance Scale, the Neglect-like Symptoms questionnaire adapted from Galer and the patient's body perception description. No full psychometric assessments were found. The Limb Laterality Recognition Task was also used in conjunction with another method.

CONCLUSIONS

Three main assessment methods for CRPS body perception disturbances are currently used. Full psychometric evaluation has not been completed for any of the assessment methods. As a consequence, we could not fully apply the COSMIN guideline. To date, there is no agreement concerning the use of a specific questionnaire or scale. The results indicate a need for further research such as psychometric properties of these questionnaires.

SIGNIFICANCE

This systematic review identified body perception disturbances assessment methods and their the psychometric properties in order to provide help and guidance to researchers and clinicians to investigate those clinical features.

Clinical and Neurophysiological Effects of Progressive Movement Imagery Training for Pathological Pain

Movement limitation is a common characteristic of chronic pain such that pain prevents the very movement and activity that is most likely to promote recovery. This is particularly the case for pathological pain states such as complex regional pain syndrome (CRPS). One clinical approach to CRPS that has growing evidence of efficacy involves progressive movement imagery training. Graded Motor Imagery (GMI) targets clinical and neurophysiological effects through a stepwise progression through implicit and explicit movement imagery training, mirror therapy and then functional tasks. Here we review experiences from over 20 years of clinical and research experience with GMI. We situate GMI in terms of its historical underpinnings, the benefits and outstanding challenges of its implementation, its potential application beyond CRPS. We then review the neuropathological targets of GMI and current thought on its effects on neurophysiological biomarkers. Perspective This article provides an overview of our experiences with graded motor imagery training over the last 20 years focussing on the treatment of CRPS. It does both cover the theoretical underpinnings for this treatment approach, biomarkers which indicate potential changes driven by GMI, and experiences for achieving optimal treatment results.

Effect of an intensive cervical traction protocol on mid-term disability and pain in patients with cervical radiculopathy: An exploratory, prospective, observational pilot study

BACKGROUND

Cervical radiculopathy is a relatively common and disabling condition involving local pain in the neck region and pain that radiates into the upper limb. Recent data suggest that cervical traction may effectively reduce disability and pain, with a dose-response relationship. The main aim of this study was therefore to evaluate the mid-term effect of an intensive cervical traction protocol for patients with cervical radiculopathy on disability, and to compare the effects with those reported by non-intensive protocols in the literature.

METHODS

We conducted a prospective open observational study of 36 patients referred by their general practitioner for symptoms suggestive of cervical radiculopathy. All patients underwent the same treatment: a 30-minute cervical traction protocol, twice a day, for five consecutive days. The main objective was the evaluation of disability at 3 months. We evaluated at baseline (D1), the end of the protocol (D5) and at mid-term (M3) disability, cervical pain, radiating pain, pain on motor imagery, presence of neuropathic pain and medication consumption. The primary outcome was the proportion of patients for whom the Neck Disability Index improved by more than the minimum clinically important difference of 7 points by M3.

RESULTS

Thirty-six patients were included in this study. The Neck Disability Index improved by more than the minimum clinically important difference in 48.3% at M3. Mean Neck Disability Index (p < .001), mean cervical VAS (p < .001), mean radiating VAS (p < .001), and mean VAS for imagined lateral flexion and rotation (p < .002) improved significantly from D1 to D5 and from D1 to M3. Consumption of medication reduced at each time point. The proportion of patients with neuropathic pain reduced from 61.1% at D1 to 33.3% at D5 and 48.3% at M3.

CONCLUSION

Disability reduced by more than the minimum clinically important difference in almost half of the participants following the intensive traction protocol. These results are encouraging and suggest that this complex condition can be treated with relatively simple methods.

Comparison of patient-led, fibromyalgia-orientated physical activity and a non-specific, standardised 6-month physical activity program on quality of life in individuals with fibromyalgia: a protocol for a randomised controlled trial

Background

Exercise has been shown to significantly improve pain and function in individuals with fibromyalgia. Research into the effectiveness of exercise is often based on standardised exercise programmes that are chosen by the investigating clinical research team. However, such programmes may not necessarily be appealing to the participating patients. Furthermore, in addition to being taught exercises, patients with chronic conditions like fibromyalgia also need to learn to manage their condition themselves and so be actively involved in their treatment. The primary aim of this study is to compare the effects of two, 6-month physical activity programs on quality of life in patients with fibromyalgia. One group followed a patient-led, fibromyalgia-orientated programme (experimental) whilst the control group followed a standard, general exercise programme.

Methods

This protocol is an open-label, two-centre, randomised, controlled superiority trial. Two treatment arms will be compared: an experimental group (patient-led, fibromyalgia-orientated exercise) and a control group (general exercise program). The control group will participate in the exercise programme currently provided in our centre, which involves general, group exercise for patients with various pathologies. The experimental group will be taught the principles of exercise specifically for fibromyalgia during a one-to-one coaching session. They will then be guided in the choice of one or several types of exercise that they enjoy. They will be instructed to perform the exercise according to the recommendations for exercise in fibromyalgia with regard to intensity, duration and frequency. The protocol will last for 6 months; participants will then be followed-up for a further 6 months. They will also be encouraged to continue exercising after the end of the protocol.

Outcomes will be evaluated at baseline, 6 and 12 months. The primary outcome will be quality of life (Fibromyalgia Impact Questionnaire) and the secondary outcomes will include measures of pain (including a visual analogue scale and the neuropathic characteristics of the pain), depression (Hospital Anxiety and Depression Scale), kinesiophobia (Tampa scale of kinesiophobia) and adherence (Polar OH1 heart rate monitor).

Discussion

The results of this study will show if patient-led, fibromyalgia-orientated exercise is more effective than a general exercise programme on fibromyalgia-related outcomes, including quality of life, and on adherence to continued exercise.

Trial registration

ClinicalTrials.gov NCT03895086. Registration no. 2018-A02881-54. Registered on 29 March 2019

The effect of knee resizing illusions on pain and swelling in symptomatic knee osteoarthritis: a case report

Introduction:

Resizing illusions that manipulate perceived body size are analgesic in some chronic pain conditions. Little is known whether such illusions may also alter other physiological features, such as swelling.

Objectives:

To determine the effects of a knee resizing illusion on knee pain and swelling in symptomatic osteoarthritis.

Methods:

This case study was extracted from a larger study evaluating the analgesic effects of resizing illusions in people with knee osteoarthritis. A mediated reality system (alters real-time video) was used to provide resizing “stretch” and “shrink” illusions of the knee. Knee pain intensity (0–100 numerical rating scale) was measured before and after illusion and after sustained (3 minutes) and repeated (n = 10) illusions. In this case study, knee swelling (leg circumference below, at, and above the knee) was also measured.

Results:

The 55-year-old male participant reported a long history of episodic knee pain and swelling that was subsequently diagnosed as severe osteoarthritis in 2013. In the first testing session, the participant experienced an increase in pain with the shrink illusion and a decrease in pain with stretch illusion. A noticeable increase in knee swelling was also observed. Thus, in sessions 2/3, swelling was also assessed. The stretch illusion decreased pain to the largest extent, but resulted in increased knee swelling. Repeated and sustained stretch illusions had cumulative analgesic effects but resulted in cumulative increases in swelling. While the shrink illusion increased pain, sustained (∼10 minutes) visual minification of the entire knee and leg reduced both pain and swelling.

Conclusion:

Our case report suggests that both pain and swelling may be modifiable by altering body-relevant sensory input in symptomatic knee osteoarthritis.

Enhanced Reality Showing Long-Lasting Analgesia after Total Knee Arthroplasty: Prospective, Randomized Clinical Trial

To overcome the limitation of short-term efficacy of virtual reality (VR), an enhanced reality (ER) analgesia, (combination of the VR, real-time motion capture, mirror therapy [MT]) involving a high degree of patients’ presence or embodiment was explored. Patients, who underwent unilateral total knee arthroplasty (TKA), received ER analgesia. The duration was 5 times a week, for 2 weeks for one group and 5 times a week, for 1 week in the other. Visual Analogue Scale (VAS) at rest and during movement, active knee range of motion (ROM) for flexion and extension were measured repeatedly. After screening 157 patients, 60 were included. Pre-interventional evaluation was performed at 6.7 days and ER was initiated at 12.4 days after surgery. Evaluation was performed at 5, 12, 33 days after the initiation of ER. Analgesia in the 2 week therapy group was effective until the third evaluation (p = 0.000), whereas in the other group, it was effective only until the second evaluation (p = 0.010). Improvement in ROM in the 2 week group was also maintained until the third evaluation (p = 0.037, p = 0.009). It could lay the foundations for the development of safe and long-lasting analgesic tools.

Crying spells triggered by thumb-index rubbing after thalamic stroke: a case report

Background

Pathologic crying, devoid of any emotional counterpart, is known to occur as a consequence of various brain stem, cortical hemispheric and cerebellar lesions or, quite exceptionally, of “dacrystic” epilepsy. The case reported here suggests that thalamic lesions may also cause crying spells, under the special circumstances described below.

Case presentation

After a mild left thalamic stroke a caucasian 77 years old man presented with crying spells with no emotional counterpart, triggered by thumb-index rubbing of his right hand. Only a modest sensation loss on right infra-orbital and nose-labial areas and the first three right fingers could be detected at clinical examination. The circumstances and processes leading to the crying spells were investigated, together with their neural substrate. Brain computerized tomography (CT), magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) were conducted. Neurophysiologic studies included Video-Electroencephalography, Electromyography, motor and sensory Evoked potentials. Active thumb-index rubbing, passive fingertips stimulation and interaction of sensory-motor stimulation with cognitive/speech activities were tested under different paradigms. A treatment with pregabalin (75 mg twice a day) was attempted. CT and MRI showed a small ischemic infarct in the left ventral postero-lateral thalamus, while fMRI led to the expected findings, i.e. a bilateral activation of the hand motor representation during the crying-triggering right-hand finger rubbing activity. Sensory potentials evoked from stimulation of the right upper limb were the only abnormal neurophysiologic test. Crying spells could be invariably evoked by both real and imagined active finger rubbing, in either the left of right hemi-space. Rubbing by an examiner was ineffective. Immersion in water (18 °C) but not oiling of the fingertips prevented the symptom. Administration and discontinuation of pregabalin 75 mg daily could be associated with suppression and reappearance of the symptom, respectively.

Conclusions

In this patient loss of sensation seemed to generate crying spells rather than the more common allodynia. As a matter of speculation, both symptoms might represent responses to a sensory loss, but in this case the pathway might have been selectively affected providing inhibition from the lateral to the medial segment of the VPLT, which is linked to the anterior cingulate (limbic) cortex engaged in emotional behaviour.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2425-z) contains supplementary material, which is available to authorized users.

Motor Imagery and Its Effect on Complex Regional Pain Syndrome: An Integrative Review

The motor imagery (MI) has been proposed as a treatment in the complex regional pain syndrome type 1 (CRPS-1), since it seems to promote a brain reorganization effect on sensory-motor areas of pain perception. The aim of this paper is to investigate, through an integrative critical review, the influence of MI on the CRPS-1, correlating their evidence to clinical practice. Research in PEDro, Medline, Bireme and Google Scholar databases was conducted. Nine randomized controlled trials (level 2), 1 non-controlled clinical study (level 3), 1 case study (level 4), 1 systematic review (level 1), 2 review articles and 1 comment (level 5) were found. We can conclude that MI has shown effect in reducing pain and functionality that remains after 6 months of treatment. However, the difference between the MI strategies for CRPS-1 is unknown as well as the intensity of mental stress influences the painful response or effect of MI or other peripheral neuropathies.

Generalization of Pain-Related Fear Using a Left-Right Hand Judgment Conditioning Task

Recent research suggests that the mere intention to perform a painful movement can elicit pain-related fear. Based on these findings, the present study aimed to determine whether imagining a movement that is associated with pain (CS+) can start to elicit conditioned pain-related fear as well and whether pain-related fear elicited by imagining a painful movement can spread towards novel, similar but distinct imagined movements. We proposed a new experimental paradigm that integrates the left-right hand judgment task (HJT) with a differential fear conditioning procedure. During Acquisition, one hand posture (CS+) was consistently followed by a painful electrocutaneous stimulus (pain-US) and another hand posture (CS-) was not. Participants were instructed to make left-right judgments, which involve mentally rotating their own hand to match the displayed hand postures (i.e., motor imagery). During Generalization, participants were presented with a series of novel hand postures with six grades of perceptual similarity to the CS+ (generalization stimuli; GSs). Finally, during Extinction, the CS+ hand posture was no longer reinforced. The results showed that (1) a painful hand posture triggers fear and increased US-expectancy as compared to a nonpainful hand posture, (2) this pain-related fear spreads to similar but distinct hand postures following a generalization gradient, and subsequently, (3) it can be successfully reduced during extinction. These effects were apparent in the verbal ratings, but not in the startle measures. Because of the lack of effect in the startle measures, we cannot draw firm conclusions about whether the "imagined movements" (i.e., motor imagery of the hand postures) gained associative strength rather than the hand posture pictures itself. From a clinical perspective, basic research into generalization of pain-related fear triggered by covert CSs such as intentions, imagined movements and movement-related cognitions might further our understanding of how pain and fear avoidance spread and persevere.

Theoretical Considerations for Chronic Pain Rehabilitation

Conventional rehabilitation of patients with chronic pain is often not successful and is frustrating for the treatment team. However, theoretical developments and substantial advances in our understanding of the neurological aspects of chronic pain are changing these experiences. Modern theoretical models of pain consider pain to be a perceptual inference that reflects a "best guess" that protective action is required. This article argues that keen observation and open and respectful clinician-patient and scientist-clinician relationships have been critical for the emergence of effective rehabilitation approaches and will be critical for further improvements. The role in modern pain rehabilitation of reconceptualizing the pain itself-by "Explaining Pain," careful and intentional observation of the person in pain, and the strategic and constant communication of safety-is emphasized. It also is suggested that better understanding of the neural mechanisms underpinning chronic pain has directly informed the development of new therapeutic approaches, which are being further refined and tested. Conventional pain treatment (where the clinician strives to find the pain-relieving medication or exercise) or pain management (where the clinician helps the patient to manage life despite unabating pain) is being replaced by pain rehabilitation, where a truly biopsychosocial approach allows clinicians to provide patients with the knowledge, understanding, and skills to reduce both their pain and disability. A brief overview is provided of the key aspects of modern pain rehabilitation and the considerations that should lead our interaction with patients with chronic pain.

Complex regional pain syndrome: a review

Complex regional pain syndrome, formally known as reflex sympathetic dystrophy, is a poorly understood condition that describes a collection of clinical symptoms and signs occurring in the peripheries most commonly after trauma. Pain is the main problem. It is generally out of proportion to the degree of injury and can be unresponsive to narcotics. In addition joint stiffness, temperature and colour changes, and swelling occur. The diagnosis and treatment are challenging for any clinician and a multidisciplinary approach is often necessary with physiotherapy, occupational therapy, and the pain team. The hand surgeon is involved for two reasons, firstly as the upper limb is the most frequently involved, and secondly because the condition may be a complication of the patient's surgery and result in a much prolonged recovery. This review elucidates the recent advances in the knowledge of the aetiology, classification and treatment of this fascinating condition.

Targeting cortical representations in the treatment of chronic pain: a review

Recent neuroscientific evidence has confirmed the important role of cognitive and behavioral factors in the development and treatment of chronic pain. Neuropathic and musculoskeletal pain are associated with substantial reorganization of the primary somatosensory and motor cortices as well as regions such as the anterior cingulate cortex and insula. What is more, in patients with chronic low back pain and fibromyalgia, the amount of reorganizational change increases with chronicity; in phantom limb pain and other neuropathic pain syndromes, cortical reorganization correlates with the magnitude of pain. These findings have implications for both our understanding of chronic pain and its prevention and treatment. For example, central alterations may be viewed as pain memories that modulate the processing of both noxious and nonnoxious input to the somatosensory system and outputs of the motor and other response systems. The cortical plasticity that is clearly important in chronic pain states also offers potential targets for rehabilitation. The authors review the cortical changes that are associated with chronic pain and the therapeutic approaches that have been shown to normalize representational changes and decrease pain and discuss future directions to train the brain to reduce chronic pain.

Complex regional pain syndrome in adults

Complex regional pain syndrome (CRPS) is a highly painful, limb-confined condition, which arises usually after trauma. It is associated with a particularly poor quality of life, and large health-care and societal costs. The causes of CRPS remain unknown. The condition's distinct combination of abnormalities includes limb-confined inflammation and tissue hypoxia, sympathetic dysregulation, small fibre damage, serum autoantibodies, central sensitization and cortical reorganization. These features place CRPS at a crossroads of interests of several disciplines including rheumatology, pain medicine and neurology. Significant scientific and clinical advances over the past 10 years hold promise both for an improved understanding of the causes of CRPS, and for more effective treatments. This review summarizes current concepts of our understanding of CRPS in adults. Based on the results from systematic reviews, treatment approaches are discussed within the context of these concepts. The treatment of CRPS is multidisciplinary and aims to educate about the condition, sustain or restore limb function, reduce pain and provide psychological intervention. Results from recent randomized controlled trials suggest that it is possible that some patients whose condition was considered refractory in the past can now be effectively treated, but confirmatory trials are required. The review concludes with a discussion of the need for additional research.

‘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.

Mirror Therapy in Complex Regional Pain Syndrome Type 1 of the Upper Limb in Stroke Patients

Background. Complex regional pain syndrome type 1 (CRPSt1) of the upper limb is a painful and debilitating condition, frequent after stroke, and interferes with the rehabilitative process and outcome. However, treatments used for CRPSt1 of the upper limb are limited. Objective. This randomized controlled study was conducted to compare the effectiveness on pain and upper limb function of mirror therapy on CRPSt1 of upper limb in patients with acute stroke. Methods. Of 208 patients with first episode of unilateral stroke admitted to the authors’ rehabilitation center, 48 patients with CRPSt1 of the affected upper limb were enrolled in a randomized controlled study, with a 6-month follow-up, and assigned to either a mirror therapy group or placebo control group. The primary end points were a reduction in the visual analogue scale score of pain at rest, on movement, and brush-induced tactile allodynia. The secondary end points were improvement in motor function as assessed by the Wolf Motor Function Test and Motor Activity Log. Results. The mean scores of both the primary and secondary end points significantly improved in the mirror group ( P < .001). No statistically significant improvement was observed in any of the control group values ( P > .001). Moreover, statistically significant differences after treatment ( P < .001) and at the 6-month follow-up were found between the 2 groups. Conclusions. The results indicate that mirror therapy effectively reduces pain and enhances upper limb motor function in stroke patients with upper limb CRPSt1.

Thinking about movement hurts: the effect of motor imagery on pain and swelling in people with chronic arm pain

OBJECTIVE

Chronic painful disease is associated with pain on movement, which is presumed to be caused by noxious stimulation. We investigated whether motor imagery, in the absence of movement, increases symptoms in patients with chronic arm pain.

METHODS

Thirty-seven subjects performed a motor imagery task. Pain and swelling were measured before, after, and 60 minutes after the task. Electromyography findings verified no muscle activity. Patients with complex regional pain syndrome (CRPS) were compared with those with non-CRPS pain. Secondary variables from clinical, psychophysical, and cognitive domains were related to change in symptoms using linear regression.

RESULTS

Motor imagery increased pain and swelling. For CRPS patients, pain (measured on a 100-mm visual analog scale) increased by a mean +/- SD of 5.3 +/- 3.9 mm and swelling by 8% +/- 5%. For non-CRPS patients, pain increased by 1.4 +/- 4.1 mm and swelling by 3% +/- 4%. There were no differences between groups (P > 0.19 for both). Increased pain and swelling related positively to duration of symptoms and performance on a left/right judgment task that interrogated the body schema, autonomic response, catastrophic thoughts about pain, and fear of movement (r > 0.42, P < 0.03 for all).

CONCLUSION

Motor imagery increased pain and swelling in patients with chronic painful disease of the arm. The effect increased in line with the duration of symptoms and seems to be modulated by autonomic arousal and beliefs about pain and movement. The results highlight the contribution of cortical mechanisms to pain on movement, which has implications for treatment.

Streamlined classification of psychopathological hand disorders: A literature review

In the surgical hand clinic, psychopathological hand disorders can be sorted into one of the following four categories: (1) factitious wound creation and manipulation; (2) factitious edema; (3) psychopathological dystonias, and (4) psychopathological sensory abnormalities and psychopathological Complex Regional Pain Syndrome. This article introduces these four categories. Pertinent literature that includes descriptions of each category's syndromes and diseases, demographic and psychological profiles, differential diagnoses, and appropriate treatment recommendations is reviewed.

Cerebral activation during motor imagery in complex regional pain syndrome type 1 with dystonia

The pathogenesis of dystonia in Complex Regional Pain Syndrome type 1 (CRPS-1) is unclear. In primary dystonia, functional magnetic resonance imaging (fMRI) has revealed changes in cerebral networks during execution of movement. The aim of this study was to determine cerebral network function in CRPS-1 patients with dystonic postures. Cerebral processing related to both execution and imagining of hand movements in patients and controls was assessed with fMRI. Eight CRPS-1 patients with dystonic postures of the right upper extremity and 17 age-matched healthy controls were studied. Compared with controls, imaginary movement of the affected hand in patients showed reduced activation ipsilaterally in the premotor and adjacent prefrontal cortex, and in a cluster comprising frontal operculum, the anterior part of the insular cortex and the superior temporal gyrus. Contralaterally, reduced activation was seen in the inferior parietal and adjacent primary sensory cortex. There were no differences between patients and controls when they executed movements, nor when they imagined moving their unaffected hand. The altered cerebral activation pattern in patients with CRPS-1 linked dystonia most likely reflects an interface between pain-associated circuitry and higher order motor control, which points at a specific mechanistic pathophysiology of this type of dystonia.

Evidence for a mismatch between the brain’s movement control system and sensory system as an explanation for some pain-related disorders

The motor-control system usually operates below our conscious level, and we only become aware of the complex interaction between desired movements and actual movements when an irregularity in the system occurs. Recently, it has been proposed that such discordances in sensorimotor function may generate pain and other somaesthetic disturbances. This article describes this model of pain and determines how it may be applied to a range of chronic pain conditions in which there is a lack of obvious causal pathology, including complex regional pain syndrome. In addition, we discuss the clinical implications of such a theory and examine how enhancing sensory feedback may reduce chronic pain.

Current management of reflex sympathetic dystrophy syndrome (complex regional pain syndrome type I)

Although no major advances have occurred in the curative treatment of reflex sympathetic dystrophy syndrome (RSDS), new pathogenic insights may soon lead to innovative approaches, which may also prove effective in alleviating some forms of neuropathic pain. Preventing nerve compression and ischemia-reperfusion injury constitute valuable measures for preventing RSDS. Vitamin C administration can also prevent RSDS, together with clonidine in high-risk patients. Short-term glucocorticoid therapy has been found effective in preventing RSDS after stroke but has not been evaluated in other situations. Beneficial effects of bisphosphonates have been documented in several placebo-controlled trials. Placebo-controlled trials of ketamine and spinal cord stimulation are in order to confirm or refute the promising results obtained in open-label studies. Mirror visual feedback was introduced recently for the rehabilitation of patients with RSDS but needs to be evaluated in randomized controlled trials.

Pathophysiology of complex regional pain syndrome

Complex regional pain syndrome (CRPS) most often follows injury to peripheral nerves or their endings in soft tissue. A combination of prostanoids, kinins and cytokines cause peripheral nociceptive sensitization. In time, the Mg(2+) block of the N-methyl-D-aspartate receptor is removed, pain transmission neurons (PTN) are altered by an influx of Ca(2+) that activates kinases for excitation and phosphatases for depression, activity-dependent plasticity that alters the firing of PTN. In time, these neurons undergo central sensitization that lead to a major physiological change of the autonomic, pain and motor systems. The role of the immune system and the sickness response is becoming clearer as microglia are activated following injury and can induce central sensitization while astrocytes may maintain the process.

Is successful rehabilitation of complex regional pain syndrome due to sustained attention to the affected limb? A randomised clinical trial

In complex regional pain syndrome (CRPS1) initiated by wrist fracture, a motor imagery program (MIP), consisting of hand laterality recognition followed by imagined movements and then mirror movements, reduces pain and disability, but the mechanism of effect is unclear. Possibilities include sustained attention to the affected limb, in which case the order of MIP components would not alter the effect, and sequential activation of cortical motor networks, in which case it would. Twenty subjects with chronic CRPS1 initiated by wrist fracture and who satisfied stringent inclusion criteria, were randomly allocated to one of three groups: hand laterality recognition, imagined movements, mirror movements (RecImMir, MIP); imagined movements, recognition, imagined movements (ImRecIm); recognition, mirror movements, recognition (RecMirRec). At 6 and 18 weeks, reduced pain and disability were greater for the RecImMir group than for the other groups (P<0.05). Hand laterality recognition imparted a consistent reduction in pain and disability across groups, however, this effect was limited in magnitude. Imagined movements imparted a further reduction in pain and disability, but only if they followed hand laterality recognition. Mirror movements also imparted a reduction in pain and disability, but only when they followed imagined movements. The effect of the MIP seems to be dependent on the order of components, which suggests that it is not due to sustained attention to the affected limb, but is consistent with sequential activation of cortical motor networks.