CRPS Patients Research Articles

Intrathecal management of complex regional pain syndrome: A case report and literature

Background and purposeComplex regional pain syndrome (CRPS) is a painful condition typically resulting from a traumatic event. Pain control in these patients is often difficult and requires a multimodal approach. Our objectives are to present a single intrathecal pain management regimen for CRPS and provide a literature review of intrathecal pain management options in CRPS. MethodsCase report from an academic pain management clinic. Case reportWe present the case of a 29-year-old female with a past medical history of multiple lumbar spine surgeries and lumbar post-laminectomy syndrome who presented to clinic with CRPS type II of the bilateral lower extremities. After failing conservative measures, she underwent placement of a successful intrathecal drug delivery system. ConclusionThe use of intrathecal medications is useful for pain control in CRPS patients. ImplicationsWe provide a framework for treatment of CRPS, which could be useful for practitioners dealing with this difficult and painful condition.

Results of the Treatment of Chronic, Refractory CRPS with Ketamine Infusions: a Preliminary Report.

Chronic, refractory complex regional pain syndrome remains very difficult to treat. A sub-anaesthetic low-dose ketamine has shown promise in advanced CRPS. We investigated the efficacy of ketamine in anaesthetic dosage in chronic, refractory CRPS patients that had failed available standard therapies. 5 female patients, aged a mean of 34 years with long-standing, a mean of 8 years', CRPS received ketamine in anaesthetic dosage over 10 days. The patients received 1-5 ketamine courses. The effect of gradual pain reduction was observed beginning on the 4(th)-5(th) day of treatment, associated with a decrease in the intensity of the allodynia (pain at light touch). No improvement in function (finger range of motion, grip strength) of the affected hands was noted in any patient. This beneficial analgesic effect was confined to 1.5-2.5 months after treatment and then pain relapsed to the baseline level. The results of this study show a short-term analgesic effect for this therapy, with no effect on movement and function of the affected limbs. Nevertheless, this method brings hope to the most severely ill patients who cannot be offered any other reasonable treatment option.

The Effects of Long-Term Ketamine Treatment on Cognitive Function in Complex Regional Pain Syndrome: A Preliminary Study.

This preliminary study aimed to investigate the effects of long-term frequent ketamine treatment on cognitive function in [AQ-A] CRPS patients. A total of 30 CRPS patients were divided into two groups based on both the duration and frequency of ketamine treatment; the long-term frequent ketamine treatment (LF) group (N = 14) and the Non-LF group (N = 16). Participants were asked to complete a questionnaire packet including demographic and clinical characteristics and potential variables affecting cognitive function. Then, they performed the neuropsychological test. Results indicated that the LF group performed significantly poorer than the Non-LF group on the digit span, digit symbol, Controlled Oral Word Association Test, and Trail Making Test, but not the Stroop task. Patients with CRPS receiving long-term frequent ketamine treatment showed impairment in cognitive function (specifically executive function) compared with those who do not. These findings may have implications for clinical assessment and rehabilitation of cognitive function in CRPS patients.

Musculoskeletal Ultrasonography in CRPS: Assessment of Muscles Before and After Motor Function Recovery with Dry Needling as the Sole Treatment

Background: Motor impairment is an important criterion in the Clinical Diagnostic Criteria (CDC) of Complex Regional Pain Syndrome type-1 (CRPS-1) as defined by International Association for Study of Pain (IASP). Objective: To describe the changes in musculoskeletal ultrasonography (MSKUSG) in CRPS-1 before and after treatment with ultrasound-guided dry needling (USGDN) in retrospective data from 44 patients. Study Design: Patients irrespective of age, gender, or cause of CRPS were included in this retrospective data analysis; the Budapest criteria for the diagnosis of CRPS were stringently adhered to. Setting: The analysis was done at Ashirvad Institute for Pain Management and Research with the database of CRPS patients who were treated between December 2005 and December 2014. Methods: The CDC, range of motion at upper extremity joints, dynamometry, Disability of arm, shoulder and hand score (DASH) and ultrasonography were documented on days one, 15, and 45. MSKUSG demonstrated loss of myoarchitecture and reduced bulk. Results: All 44 patients received USGDN as the sole intervention with medications and physiotherapy. MSKUSG at 15 and 45 days after starting USGDN showed a return of normalcy to the myoarchitecture and muscle bulk increase that coincided with the disappearance of CDC and a progressive and predictable improvement of the DASH scores in all the 44 patients. Limitation: The analysis focuses on only 2 parameters: the musculoskeletal changes of the forearm flexors and extensors on ultrasound guidance and the efficacy of the dry needling treatment. It is not a comparative study with another accepted form of treatment or intervention. We have not looked into the age and gender predilection of the condition owing to the small sample size of the study. Analysis of long term maintenance of relief and rehabilitation of the disability were limited to one year. Conclusion: Myofascial pathology of co-contraction appears to cause CDC of CRPS and probable ischemic loss of myoarchitecture. Relief of co-contraction with USGDN allowed resolution of tenosynovitis causing the CDC and return of normal myoarchitecture. Key words: CRPS-1, co-contraction, motor impairment, disability, dry needling, musculoskeletal ultrasonography

Complex regional pain syndrome type I in children. Clinical description and quality of life

IntroductionComplex regional pain syndrome type 1 (CRPS I) in children differs from its adult counterpart and relevant literature is scarce. Our aim was to investigate potential risk factors and to assess midterm outcome and quality of life. Material and methodsMedical records of patients diagnosed with CRPS I between 2004 and 2012 were analyzed. Patients and parents were called for a phone interview including the PEDS Quality of Life 4-0 questionnaire. Results were compared to a control group matched for age, gender and socio-economic status. ResultsSeventy-three patients were included (64 girls, 9 boys). Mean age at diagnosis was 11.5 years and mean time to diagnosis was 14.2 months. The lower limb was affected in 89% of cases. Allodynia, coldness and cyanosis were noted in 95%, 81% and of 74% of cases, respectively. Forty-nine percent of patients reported a physical injury. Multivariate analysis showed a strong association with being anxious (OR = 44.9, 95% CI [7.4–273]), presence of an atopic background (OR = 25.0, 95% CI: [4.6–135]), being good to excellent school performers (OR = 8.4 95% CI [1.3–52.1]), and having trouble falling asleep (OR = 5.3, 95% CI [1.6–17.0]). At a mean 37 months’ follow-up (12–102), PEDS QL 4-0 score was significantly lower in CRPS patients compared to controls. Fifty-seven percent of patients acknowledged healing and 55% had presented a relapse. ConclusionChildhood onset CRPS I affects predominantly preadolescent girls at the ankle. The present study highlights the relatively poor outcome, especially its physical and emotional aspects and the large role of psychology. Level of evidenceIV.

V33. Functional imaging of somatosensory finger representation and intracortical inhibition modulation in complex regional pain syndrome

Neurophysiological pathology in CRPS type I is characterized by somatosensory and motor deficits. Transcranial magnetic stimulation (TMS) and functional MRI reveal decreased short intracortical inhibition (SICI) and smaller representation distance in the hand region of primary somatosensory cortex (S1) between the first and fifth digit in CRPS. Interestingly, an application of anesthetic cream to the forearm increases spatial tactile resolution (STR) and also SICI of hand muscles in healthy participants. As such, this intervention might be suited to reverse pathologic findings in CRPS patients and tested this in a double blinded placebo controlled study. In addition we used high spatial resolution fMRI of the thumb (D1) and pinky (D5) S1 BA 3b representation before and after intervention. Patients showed decreased STR over D1 (tip of thumb) on their affected side if compared to the unaffected side ( t = 2.31; p t = 3.0; p t = 2.22; p

Stuck with a CRPS patient - what else to offer a CRPS patient?

Complex regional pain syndrome or CRPS includes painful conditions characterised by persistent pain, confined to a particular region of the body that is seemingly disproportionate to the initiating injury. The pain is usually associated with any of the following: abnormal sensory, motor, sudomotor, vasomotor or trophic changes, and shows variable progression over time. Many CRPS patients have severe pain and disability as well as impact on sleep and mood, and are often challenging to manage. Management must begin with a thorough assessment of symptoms and signs as well as the psychosocial impact of the pain. The diagnosis of CRPS is usually a clinical one with no specific confirmatory tests required, and treatment should take a multidisciplinary, multimodal approach, with the overall aim of improving not just pain but more importantly, function and mood. Modalities of treatment include medications, interventions (sympathetic nerve blocks), physical therapy and psychological therapy. Appropriate medications include antineuropathic agents including tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors (SNRIs) and anticonvulsants like the alpha2delta ligands. Exercise and rehabilitation with aim of return of function is a crucial part of the management; often, pain prevents the patient from doing effective exercise, and use of opioid medications (weak opioids like tramadol or even strong opioids like oxycodone) may be necessary to enable patients to start their physical therapy. Other modalities of treatment include Mirror therapy and sympathetic blocks (for patients with sympathetically maintained pain). All patients must also be taught to do relaxation and to use it to manage their pain. Patients who are very disabled by their pain, especially those whose pain does not decrease with appropriate medications, may require cognitive behavioural interventions including intensive pain management programs which teach patients how to function normally despite persistent pain. Our experience in Selayang hospital with patients with difficult-to-manage CRPS will be discussed in the presentation.

P.2.h.005 Somatic pain modulation and its role in typifying the dimension of pain in depression

with respect to suicide risk factors in CRPS patients are available. The purpose of this study was to assess risk factors for suicidal ideation in patients with CRPS and also we evaluated psychiatric comorbidity in this population. Methods: Based on criteria established by the International Association for the Study of Pain, 39 patients diagnosed with CRPS Type 1 or Type 2 were enrolled in this study. Suicidal ideation was assessed using item 3 of the Hamilton Depression Rating Scale (HAMD). The low-suicidal ideation (SI) group included those with scores of 1 or below on HAMD item 3 (0 = suicide ideation absent, 1 = feels that life is worth living), and the high-SI group included those with HAMD item 3 scores above 1. Symptoms of pain were evaluated using the short form of the McGill Pain Questionnaire (SF-MPQ). Psychiatric symptoms were assessed in using the Structured Clinical Interview for DSM-IV Disorders (SCID-I; SCID-II), the HAMD, the Hamilton Anxiety Rating Scale (HAMA), the Global Assessment of Functioning Scale (GAF), and the Pittsburgh Sleep Quality Index (PSQI). Betweengroup comparisons involving categorical data were performed using the chi-square statistic corrected for continuity; between-group comparisons involving continuous data (age and socio-economic status) were calculated using Student’s t-test. Pearson’s correlation analysis was used to assess correlations between suicidal ideation and other variables. Results: 33 (84.6%) were diagnosed with CRPS Type 1, and six (15.4%) were diagnosed with CRPS Type II. Males accounted for 61.5% (n = 24) of the patients, and females 38.5% (n = 15). The mean age of the patients at their initial evaluation at the pain clinic was 37.87 (±11.94) years, and the mean number of years of education was 12.49 (±2.68) years. Patients reported having CRPS symptoms for a mean of 2.84 years (±2.49) at the time of evaluation and had been prescribed 4.28 (range, 0−7) different kinds of medications on average. Twenty-nine patients (74.4%) were at high risk and 10 (25.6%) were at low risk for suicidal ideation. Risk factors significantly associated with suicidal ideation included depression (p= 0.002), severity of pain (p= 0.024), and low scores on the GAF (p= 0.027). No significant correlations were found between suicidal ideation and anxiety or quality of sleep. Conclusions: CRPS is recognized as one of the most difficult conditions to treat among pain syndromes. This study found that the factors most strongly associated with suicide in patients with CRPS were depression, pain severity, and general functioning. These results suggest that psychiatric evaluation and intervention should be included in the treatment of CRPS.

Complex Regional Pain Syndrome Type 1 (CRPS): A brief exploratory review

This paper is written by health psychologists (JB) working with CRPS patients at the Royal National Hospital for Rheumatic Diseases in Bath. The other health psychologist works at the Royal National Hospital for Rheumatic Diseases in a clinical capacity, advising patients on quality of life and on how to improve their coping strategies. The outpatients are seen in a face–to face one–to–one interview and the inpatients are sometimes seen in groups. CRPS is quite a rare condition and this review is an attempt to bring this syndrome to the attention of trainee health psychologists. It differs from other chronic pain conditions in that it is often accompanied by unusual signs like excessive hair/nail growth. In addition it is a good example of how the mind and body work together to produce a wide range of signs and symptoms that have a profound effect on the patients’ quality of life. Where it was initially believed that the condition was largely psychogenic, a wide body of work now shows that the symptoms are more physiological and neurological in nature.

Concomitant Glomus Tumor with CRPS in the Hand

Glomus tumors are benign tumors that account for 1% to 5% of all soft tissue tumors of the hand and are characterized by a triad of sensitivity to cold, localized tenderness and severe paroxysmal pain. Paroxysmal pain is a symptom common not only in glomus tumors but also in CRPS, and the hand is one of the commonly affected sites in patients with both glomus tumors and CRPS. Therefore, it is not easy to clinically diagnose glomus tumors superimposed on already affected region of CRPS patients. We report a case of glomus tumor concomitantly originating with CRPS at the hand.

Intact 2D-form recognition despite impaired tactile spatial acuity in complex regional pain syndrome type I

Tactile acuity measured by 2-point discrimination performance is impaired in patients with complex regional pain syndrome type I (CRPS-I). This is mirrored by pain-associated shrinkage of the cortical representation of the affected limb. We investigated whether, also, more complex tactile performance assessed by a dynamic 2D-form perception task is disturbed in CRPS-I patients. Therefore, we developed a Braille-like recognition task (BT) for geometrical dot pattern identification by dynamic touch. We studied 47 healthy volunteers (Study I) and compared them to 16 CRPS-I patients (Study II). Besides recognition time and error quote of the BT, we assessed static 2-point discrimination thresholds (TPDT). In healthy subjects, the performance in the BT correlated significantly with age and TPDT. In CRPS patients, TPDT was significantly increased on the affected side compared to sex- and age-matched controls from study I (2.98±0.84mm vs 2.05±0.82mm, P<0.01). The performance in the BT was not impaired in CRPS-I patients (compared to sex- and age-matched controls from study I) and was not correlated to the TPDT. The intact 2D-form recognition ability in CRPS-I patients might be explained by intact dynamic tactile and proprioceptive functions, which appear to be uncompromised by the impaired static tactile perception, provided that the spacing of the dot pattern is above the individual tactile acuity. These intact 2D-form perception capacities may also be related to higher sensory integration functions like the visual system and intact semantic understanding, which may be spared by the cortical reorganization phenomena in CRPS-I.

Heart Rate Variability in Complex Regional Pain Syndrome during Rest and Mental and Orthostatic Stress

Complex regional pain syndrome (CRPS) is a pain condition with regional sensory and autonomic abnormalities in the affected limb. The authors studied systemic autonomic and hemodynamic function in CRPS patients during rest, and during orthostatic and mental arithmetic stress. Twenty patients with CRPS and 20 age-, sex-, and body mass index-matched control subjects participated. Mean values of heart rate variability, baroreceptor sensitivity, blood pressure, stroke volume, cardiac output, and total peripheral resistance were estimated during supine rest and 60° tilt-table testing. On a separate day, heart rate variability was also measured during mental arithmetic stress testing induced by a paced auditory serial addition task. Heart rate was increased and heart rate variability reduced in patients with CRPS patients compared with control subjects during rest and mental and orthostatic stress, whereas baroreceptor sensitivity was unaffected. When tilted from supine to upright position, patients with CRPS were not able to preserve cardiac output in comparison with control subjects, and they exhibited an exaggerated increase in the total peripheral resistance. The hemodynamic changes correlated to pain duration but not to pain intensity. The increased heart rate and decreased heart rate variability in CRPS suggest a general autonomic imbalance, which is an independent predictor for increased mortality and sudden death. The inability of the patients to protect their cardiac output during orthostatic stress was aggravated with the chronicity of the disease.

Ketamine as Adjunctive Anesthesia in Refractory Complex Regional Pain Syndrome Patients: A Case Series

Complex regional pain syndrome most often follows peripheral soft tissue and nerve injury, fractures, and surgical procedures. The pain is out of proportion to the severity of the injury, spreads beyond a nerve or root territory and increases over time. In general, recommendations for anesthesia for these patients requiring surgery include sympathetic blockade or intravenous regional anesthesia as well as sympathetic blockade in conjunction with lidocaine. Quite often surgery for these patients seriously aggravates their condition. This is a retrospective evaluation of a case series of the use of ketamine as adjunctive anesthesia in twenty five refractory long standing complex regional pain syndrome patients. All patients met the International Association for the Study of Pain criteria for diagnosis. Ketamine was administered intravenously over four hours from the start of the procedure with midazolam and clonidine in addition to their standard anesthesia. At the end of the procedure, an additional dose of midazolam was administered. Lorazepam was used for restlessness if necessary for three nights after the procedure. All twenty five patients had no exacerbation of their symptoms and signs and no spread of their CRPS. This study supports the effective use of ketamine, midazolam and clonidine as adjunctive anesthesia in severe refractory CRPS patients undergoing a surgical procedure.

P19.13 Pain reduction in a CRPS patient due to tDCS and sensorimotor training. A single case study

P19.13 Pain reduction in a CRPS patient due to tDCS and sensorimotor training. A single case study

Fixed Dystonia in Complex Regional Pain Syndrome: a Descriptive and Computational Modeling Approach

BackgroundComplex regional pain syndrome (CRPS) may occur after trauma, usually to one limb, and is characterized by pain and disturbed blood flow, temperature regulation and motor control. Approximately 25% of cases develop fixed dystonia. Involvement of dysfunctional GABAergic interneurons has been suggested, however the mechanisms that underpin fixed dystonia are still unknown. We hypothesized that dystonia could be the result of aberrant proprioceptive reflex strengths of position, velocity or force feedback.MethodsWe systematically characterized the pattern of dystonia in 85 CRPS-patients with dystonia according to the posture held at each joint of the affected limb. We compared the patterns with a neuromuscular computer model simulating aberrations of proprioceptive reflexes. The computer model consists of an antagonistic muscle pair with explicit contributions of the musculotendinous system and reflex pathways originating from muscle spindles and Golgi tendon organs, with time delays reflective of neural latencies. Three scenarios were simulated with the model: (i) increased reflex sensitivity (increased sensitivity of the agonistic and antagonistic reflex loops); (ii) imbalanced reflex sensitivity (increased sensitivity of the agonistic reflex loop); (iii) imbalanced reflex offset (an offset to the reflex output of the agonistic proprioceptors).ResultsFor the arm, fixed postures were present in 123 arms of 77 patients. The dominant pattern involved flexion of the fingers (116/123), the wrists (41/123) and elbows (38/123). For the leg, fixed postures were present in 114 legs of 77 patients. The dominant pattern was plantar flexion of the toes (55/114 legs), plantar flexion and inversion of the ankle (73/114) and flexion of the knee (55/114).Only the computer simulations of imbalanced reflex sensitivity to muscle force from Golgi tendon organs caused patterns that closely resembled the observed patient characteristics. In parallel experiments using robot manipulators we have shown that patients with dystonia were less able to adapt their force feedback strength.ConclusionsFindings derived from a neuromuscular model suggest that aberrant force feedback regulation from Golgi tendon organs involving an inhibitory interneuron may underpin the typical fixed flexion postures in CRPS patients with dystonia.

Elevated blood levels of inflammatory monocytes (CD14+CD16+) in patients with complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain disorder. Although its pathophysiology is not completely understood, neurogenic inflammation is thought to play a significant role. Microglia and astrocytes are activated following tissue injury or inflammation and have been reported to be both necessary and sufficient for enhanced nociception. Blood-borne monocytes/macrophages can infiltrate the central nervous system (CNS) and differentiate into microglia resulting in hypersensitivity and chronic pain. The primary aim of this study was to evaluate the proportion of the proinflammatory CD14(+) CD16(+) monocytes as well as plasma cytokine levels in blood from CRPS patients compared to age- and gender-matched healthy control individuals. Forty-six subjects (25 CRPS, 21 controls) were recruited for this study. The percentage of monocytes, T, B or natural killer (NK) cells did not differ between CRPS and controls. However, the percentage of the CD14(+) CD16(+) monocyte/macrophage subgroup was elevated significantly (P<0·01) in CRPS compared to controls. Individuals with high percentage of CD14(+) CD16(+) demonstrated significantly lower (P<0·05) plasma levels on the anti-inflammatory cytokine interleukin (IL)-10. Our data cannot determine whether CD14(+) CD16(+) monocytes became elevated prior to or after developing CRPS. In either case, the elevation of blood proinflammatoty monocytes prior to the initiating event may predispose individuals for developing the syndrome whereas the elevation of blood proinflammatory monocytes following the development of CRPS may be relevant for its maintenance. Further evaluation of the role the immune system plays in the pathogenesis of CRPS may aid in elucidating disease mechanisms as well as the development of novel therapies for its treatment.

Dexmedetomidine for the treatment of acute pain from complex regional pain syndrome

Dexmedetomidine for the treatment of acute pain from complex regional pain syndrome

Ketamine Infusion Successful in Some Patients

We read with interest the observational re-port of Kapural et al (1) titled “Opioid-sparing effect of intravenous outpatient ketamine infu-sions appears short-lived in chronic-pain patients with high opioid requirements.” While we do not disagree that in some patients the pain-relieving effect of intravenous ketamine can be short-lived, we do disagree with the authors’ conclusion that this is not a feasible option for pain relief in this chronic pain population. The statement imply-ing that the infusion was not successful is unfor-tunately misleading and misses the more obvious and important clinical and scientific questions of why some patients responded and others did not. Despite the lack of internal validity in their study design, there was still improved analgesia in some patients for up to 6 months, similar to our experi-ence with low and moderate dose infusion of ket-amine in the CRPS population (2,3).We would like to briefly discuss some of the critical aspects relating to this study:The study is a retrospective analysis, of a non-homogenous population with multiple diagnoses, and lacks a true matched control population. The studies quoted, specifically those of Koffler et al (4), Goldberg et al (2), and Sigtermans et al (5) all deal with a single group of patients, those with a diagnosis of CRPS. The authors regrettably fail to mention the placebo controlled trial of Schwartz-man et al (6) that reported significant decreases in multiple pain measures after a 10-day ketamine infusion in patients with CRPS who had failed all other therapies. Also significant in Kapural et al’s study (1) was the fact that 6 months post treat-ment, almost 50% (5/11) of the subjects main-tained their opioid use at less than 50% of their baseline. In our opinion this seems to represent a clinically significant improvement.The notion of expense outweighing benefit can-not be supported by the study of Kapural et al (1). The low dose outpatient infusion is performed simi-larly to blood transfusions and is covered by insur-ance in most cases. The moderate dose 5-day infusion in the inpatient setting is performed with telemetry monitoring and is often covered by insurance in our practice. The high dose therapy is not performed in the United States and does require ICU admission and intensive monitoring. This is a recommended treatment to reduce opioid load in the chronic pain patient, but is reserved only for the most refractory cases of CRPS.Finally, we have recently reported the results from an initial study of the plasma concentrations of ketamine and norketamine, and other major ket-amine metabolites in CRPS patients (7). The data indicate that the ketamine metabolites, other than norketamine, were the predominant circulating me-tabolites and suggest that these compounds play a role in ketamine-related pain relief. Thus, it is likely that metabolic differences based upon pharmacoge-netic factors play a role in the determination of re-sponder and non-responder populations. Once these factors are identified, it will be possible to preselect candidates for treatment with ketamine and to indi-vidualize their treatment.We therefore continue to support a role for ketamine and/or its metabolites in the treatment of chronic pain in the patients with CRPS.MIchael E. Goldberg, MDProfessor and ChiefDepartment of AnesthesiologyCooper University HospitalUMDNJNewark, NJE-mail: goldberg-Mike@cooperhealth.edu

Die „Sudeck-Persönlichkeit“: Mythos und Fiktion

In analogy to the thesis of "pain-proneness", conceptualised by G. Engel more than 50 years ago, the idea of a unique structure in personality emerged, which was given a causal meaning in the development of Sudeck's Disease (now known as complex regional pain syndrome - CRPS), of which the pathogenesis is particularly unknown until today. It was supposed that certain psychological traits predispose one to develop CRPS. Predisposition in this context was apprehended as a personal susceptibility to produce and maintain an excessive reaction to nociceptive stimulations. This model has been maintained for a long time and was the subject of scientific examination just in the last two decades. Some publications reporting sporadic correlations between CRPS and certain personality traits, for example anxiety, neuroticism and depressive mood, are presented as are also 15 current empirical studies and five reviews, which deal in a more differentiated manner with the formulated question and lead to sobering results. The relevant state of research as well as the fundamental and methodical difficulties in regard to verifying a CRPS personality or pain-prone personality are discussed critically. In general, there is a lack of high-quality relevant studies. Some retrospective/cross-sectional studies yield contradictory results regarding psychological problems in patients with CRPS but the majority shows no association, and studies with higher methodological quality tend to the conclusion of no relationship between psychological factors like depression, anxiety, neuroticism, or anger and CRPS. Especially, the few prospective studies do not report such a relationship, psychological factors are not associated with CRPS onset. Compared to other patients with chronic pain there is no unique disturbed psychological profile and no higher degree of psychosocial disturbance in CRPS patients. In all, the results of research cannot confirm the hypothesis of correlations between psychological and psychosocial factors and the pathogenesis of CRPS. Furthermore, there is no evidence for the existence of a unique CRPS personality or psychosocial pattern. The findings are in conformity with the outcome of research referring to the general pain-prone personality, which was abandoned due to the lack of success. It has been shown that there is a non-specific and non-linear relationship between personality and pain, there is no aetiological link. The observed modifications in behaviour and personality of CRPS patients, in particular depression and anxiety, are a consequence of the persisting pain disease and its considerable resistance towards treatment and not the cause. Although many patients with CRPS have been stigmatised as being psychologically different, a relationship between this disease and several psychological factors cannot be derived. The idea of an existing "Sudeck personality" as well as the search for such a predisposing personality structure are obsolete and useless. Management of pain and pain-related impairments, however, are based on the personality of the affected persons.

Left is where the L is right. Significantly delayed reaction time in limb laterality recognition in both CRPS and phantom limb pain patients

The body schema is based on an intact cortical body representation. Its disruption is indicated by delayed reaction times (RT) and high error rates when deciding on the laterality of a pictured hand in a limb laterality recognition task. Similarities in both cortical reorganisation and disrupted body schema have been found in two different unilateral pain syndromes, one with deafferentation (phantom limb pain, PLP) and one with pain-induced dysfunction (complex regional pain syndrome, CRPS). This study aims to compare the extent of impaired laterality recognition in these two groups. Performance on a test battery for attentional performance (TAP 2.0) and on a limb laterality recognition task was evaluated in CRPS ( n = 12), PLP ( n = 12) and healthy subjects ( n = 38). Differences between recognising affected and unaffected hands were analysed. CRPS patients and healthy subjects additionally completed a four-day training of limb laterality recognition. Reaction time was significantly delayed in both CRPS (2278 ± 735.7 ms) and PLP (2301.3 ± 809.3 ms) compared to healthy subjects (1826.5 ± 517.0 ms), despite normal TAP values in all groups. There were no differences between recognition of affected and unaffected hands in both patient groups. Both healthy subjects and CRPS patients improved during training, but RTs of CRPS patients (1874.5 ± 613.3 ms) remain slower ( p < 0.01) than those of healthy subjects (1280.6 ± 343.2 ms) after four-day training. Despite different pathomechanisms, the body schema is equally disrupted in PLP and CRPS patients, uninfluenced by attention and pain and cannot be fully reversed by training alone. This suggests the involvement of complex central nervous system mechanisms in the disruption of the body schema.