Welcome to the March CRPS Bugle, an update on the latest research into complex regional pain syndrome, also known as reflex sympathetic dystrophy (RSD).
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J Foot Ankle Surg. 2014 Mar 5. pii: S1067-2516(14)00007-6. doi: 10.1053/j.jfas.2014.01.006.
Incidence of Complex Regional Pain Syndrome after Foot and Ankle Surgery.
Rewhorn MJ1, Leung AH2, Gillespie A3, Moir JS3, Miller R4.
Complex regional pain syndrome (CRPS) is an uncommon complication of orthopedic surgery, and few investigators have considered the incidence in foot and ankle surgery. In the present retrospective cohort study of 390 patients who had undergone elective foot and/or ankle surgery in our department from January to December 2009, the incidence of postoperative CRPS was calculated and explanatory variables were analyzed. A total of 17 patients (4.36%) were identified as meeting the International Association for the Study of Pain criteria for the diagnosis of CRPS. Of the 17 patients with CRPS, the mean age was 47.2 ± 9.7 years, and 14 (82.35%) were female. All the operations were elective, and 9 (52.94%) involved the forefoot, 3 (17.65%) the hindfoot, 3 (17.65%) the ankle, and 2 (11.76%) the midfoot. Twelve patients (70.59%) had new-onset CRPS after a primary procedure, and 5 (29.41%) had developed CRPS after multiple surgeries. Three patients (17.65%) had documented nerve damage intraoperatively and thus developed new-onset CRPS type 2. Blood test results were available for 14 patients (82.35%) at a minimum of 3 months postoperatively, and none had elevated inflammatory markers. Five of the patients (29.41%) were smokers, and 8 (47.06%) had had a pre-existing diagnosis of anxiety and/or depression. From our findings, we recommend that middle-age females and those with a history of anxiety or depression, who will undergo elective foot surgery, should be counseled regarding the risk of developing CRPS during the consent process. We recommend similar studies be undertaken in other orthopedic units, and we currently are collecting data from other orthopedic departments within Scotland
Rehabil Psychol. 2014 Mar 10.
Thought Intrusion Among Adults Living With Complex Regional Pain Syndrome.
Lohnberg JA, Altmaier EM.
Purpose: This study investigated the presence and influence of intrusive thoughts among adults previously diagnosed with complex regional pain syndrome. Method: The present study used an Internet-based survey completed by a sample (N = 326) from two national organizations. Results: After controlling for age, gender, and pain level, intrusive thoughts were significantly related to disability and health-related quality of life. Conclusions/Implications: Intrusive thoughts about the inciting event that caused CRPS uniquely influenced pain and quality of life, suggesting a potential mechanism to target for intervention. Understanding factors that relate to maintenance of CRPS and its resulting disability will help in the development of treatments to improve quality of life.
Brain. 2013 Jul;136(Pt 7):2038-49. doi: 10.1093/brain/awt150. Epub 2013 Jun 13.
Secondary and primary dystonia: pathophysiological differences.
Kojovic M1, Pareés I, Kassavetis P, Palomar FJ, Mir P, Teo JT, Cordivari C, Rothwell JC, Bhatia KP, Edwards MJ.
Primary dystonia is thought to be a disorder of the basal ganglia because the symptoms resemble those of patients who have anatomical lesions in the same regions of the brain (secondary dystonia). However, these two groups of patients respond differently to therapy suggesting differences in pathophysiological mechanisms. Pathophysiological deficits in primary dystonia are well characterized and include reduced inhibition at many levels of the motor system and increased plasticity, while emerging evidence suggests additional cerebellar deficits. We compared electrophysiological features of primary and secondary dystonia, using transcranial magnetic stimulation of motor cortex and eye blink classical conditioning paradigm, to test whether dystonia symptoms share the same underlying mechanism. Eleven patients with hemidystonia caused by basal ganglia or thalamic lesions were tested over both hemispheres, corresponding to affected and non-affected side and compared with 10 patients with primary segmental dystonia with arm involvement and 10 healthy participants of similar age. We measured resting motor threshold, active motor threshold, input/output curve, short interval intracortical inhibition and cortical silent period. Plasticity was probed using an excitatory paired associative stimulation protocol. In secondary dystonia cerebellar-dependent conditioning was measured using delayed eye blink classical conditioning paradigm and results were compared with the data of patients with primary dystonia obtained previously. We found no difference in motor thresholds, input/output curves or cortical silent period between patients with secondary and primary dystonia or healthy controls. In secondary dystonia short interval intracortical inhibition was reduced on the affected side, whereas it was normal on the non-affected side. Patients with secondary dystonia had a normal response to the plasticity protocol on both the affected and non-affected side and normal eye blink classical conditioning that was not different from healthy participants. In contrast, patients with primary dystonia showed increased cortical plasticity and reduced eye blink classical conditioning. Normal motor cortex plasticity in secondary dystonia demonstrates that abnormally enhanced cortical plasticity is not required for clinical expression of dystonia, and normal eye blink conditioning suggests an absence of functional cerebellar involvement in this form of dystonia. Reduced short interval intracortical inhibition on the side of the lesion may result from abnormal basal ganglia output or may be a consequence of maintaining an abnormal dystonic posture. Dystonia appears to be a motor symptom that can reflect different pathophysiological states triggered by a variety of insults.
Int J Rheum Dis. 2014 Feb;17(2):156-8. doi: 10.1111/1756-185X.12140. Epub 2013 Jun 24.
Antioxidant profile in patients with complex regional pain syndrome type I.
Baykal T1, Seferoglu B, Karsan O, Kiziltunc A, Senel K.
Complex regional pain syndrome (CRPS) type I is one of the most important problems with regard to physical medicine and rehabilitation. CRPS may cause not only higher therapeutic costs but also greater work time loss. The mechanism and pathogenesis of CRPS still remains unknown. Some findings indicating oxidative stress have been reported. This study was carried out to determine the role of oxidative stress in patients with CRPS.
MATERIALS AND METHODS:
Twenty patients (13 women and seven men) with CRPS and 20 age- and sex-matched healthy controls were enrolled in this study. Complex regional pain syndrome was diagnosed according to the modified International Association for the Study of Pain (IASP) criteria. We evaluated demographic, clinical and laboratory characteristics of the patients. Antioxidant enzymatic activities consisting of serum superoxide dismutase (SOD), glutathion peroxidase (GPX) and glutathione S-transferase (GST) activities were measured using appropriate methods and compared with healthy controls.
The mean age of the patients was 39.5 years and the mean duration of symptoms was 5.5 months. Complex regional pain syndrome devoleped after a traumatic event in 90% of patients. In 10% of patients there were no traumatic events. SOD, GPX and GST levels were significantly higher in patients with CRPS than healthy controls (P = 0.012, P = 0.036 and P = 0.016, respectively).
Our findings suggest a possible role of oxidative stress in the pathogenesis of CRPS
J Pain. 2014 Feb 11. pii: S1526-5900(14)00565-3. doi: 10.1016/j.jpain.2014.01.500.
The Outcome of Complex Regional Pain Syndrome Type 1: A Systematic Review
Bean DJ1, Johnson MH2, Kydd RR3.
The purpose of this systematic review was to examine the outcome of complex regional pain syndrome (CRPS) type-1. We searched Medline, Embase and Psychinfo for relevant studies, and included 18 studies, with 3991 participants, in this review. The following data were extracted: study details, measurement tools used, and rates or severity scores for the symptoms/signs of CRPS at baseline and follow-up, or in groups of patients with different disease durations. A quality assessment revealed significant limitations in the literature, with many studies utilising different diagnostic criteria. The 3 prospective studies demonstrated that for many patients, symptoms improve markedly within 6-13 months of onset. The 12 retrospective studies had highly heterogeneous findings, documenting lasting impairments in many patients. The 3 cross-sectional studies showed that rates of pain and sensory symptoms were highest amongst those with the longest duration of CRPS. Additionally, most studies showed that motor symptoms (stiffness and weakness) were the most likely to persist whilst sudomotor and vasomotor symptoms were the most likely to improve. Overall, this suggests that some CRPS patients make a good early recovery whilst others develop lasting pain and disability. As yet little is known about the prognostic factors that might differentiate between these groups.
We found evidence that many CRPS patients recover within 6-13 months, but a significant number experience some lasting symptoms, and some experience chronic pain and disability. The quality of the evidence was poor. Future research should examine the factors associated with recovery and identify those at risk of poor outcomes
Eur J Neurosci. 2014 Feb;39(3):508-19. doi: 10.1111/ejn.12462
The neurobiology of skeletal pain.
Disorders of the skeleton are one of the most common causes of chronic pain and long-term physical disability in the world. Chronic skeletal pain is caused by a remarkably diverse group of conditions including trauma-induced fracture, osteoarthritis, osteoporosis, low back pain, orthopedic procedures, celiac disease, sickle cell disease and bone cancer. While these disorders are diverse, what they share in common is that when chronic skeletal pain occurs in these disorders, there are currently few therapies that can fully control the pain without significant unwanted side effects. In this review we focus on recent advances in our knowledge concerning the unique population of primary afferent sensory nerve fibers that innervate the skeleton, the nociceptive and neuropathic mechanisms that are involved in driving skeletal pain, and the neurochemical and structural changes that can occur in sensory and sympathetic nerve fibers and the CNS in chronic skeletal pain. We also discuss therapies targeting nerve growth factor or sclerostin for treating skeletal pain. These therapies have provided unique insight into the factors that drive skeletal pain and the structural decline that occurs in the aging skeleton. We conclude by discussing how these advances have changed our understanding and potentially the therapeutic options for treating and/or preventing chronic pain in the injured, diseased and aged skeleton