The 4th International Congress on Neuropathic Pain is currently in full swing in Toronto. You can follow the tweets via the trend #NeuPSIG and #neupsig. Here are some of the papers from the speakers.
Complex regional pain syndrome, prototype of a novel kind of autoimmune disease.
Autoimmun Rev. 2013 Apr;12(6):682-6. doi: 10.1016/j.autrev.2012.10.015. Epub 2012 Dec 6.
Goebel A, Blaes F.
Pain Research Institute, Department of Translational Medicine, Liverpool University, Liverpool, UK; The Walton Centre NHS Foundation Trust, Liverpool, UK. Electronic address: firstname.lastname@example.org.
Complex regional pain syndrome (CRPS) is a painful condition, which arises in a limb after trauma. CRPS can profoundly affect patients’ quality of life, and there is no cure. CRPS is associated with limb-confined sensory, motor, skin, bone and autonomic abnormalities. Recent research has shown that some patients respond to treatment with immunoglobulins, and that a majority have IgG serum-autoantibodies directed against, and activating autonomic receptors. CRPS serum-IgG, when transferred to mice elicits abnormal behaviour. These results suggest that CRPS is associated with an autoantibody-mediated autoimmune process in some cases. CRPS has unusual features, including a non-destructive, and regionally-confined course. We propose that CRPS constitutes a prototype of a new kind of autoimmunity, which we term ‘IRAM’ (injury-triggered, regionally-restricted autoantibody-mediated autoimmune disorder with minimally-destructive course). Understanding autoimmune contribution to CRPS should allow the exploration of novel treatment modalities in the future. Additional ‘functional’ disorders, painful or painless may be autoimmune in nature.
Pain Pract. 2013 Mar 14. doi: 10.1111/papr.12049. [Epub ahead of print]
Mast Cells: A New Target in the Treatment of Complex Regional Pain Syndrome?
Dirckx M, Groeneweg G, van Daele PL, Stronks DL, Huygen FJ.
Center for Pain Medicine, Erasmus MC, Rotterdam, The Netherlands.
There is convincing evidence that inflammation plays a pivotal role in the pathophysiology of complex regional pain syndrome (CRPS). Besides inflammation, central sensitization is also an important phenomenon. Mast cells are known to be involved in the inflammatory process of CRPS and also play a role (at least partially) in the process of central sensitization. In the development of a more mechanism-based treatment, influencing the activity of mast cells might be important in the treatment of CRPS. We describe the rationale for using medication that counteracts the effects of mast cells in the treatment of CRPS.
Clin J Pain. 2012 May;28(4):355-63. doi: 10.1097/AJP.0b013e31822efe30.
Effect of immunomodulating medications in complex regional pain syndrome: a systematic review.
Dirckx M, Stronks DL, Groeneweg G, Huygen FJ.
Erasmus MC, Rotterdam, The Netherlands. email@example.com
Different mechanisms are involved in a complex network of interactions resulting in the painful and impairing disorder, complex regional pain syndrome (CRPS). There is convincing evidence that inflammation plays a pivotal role in the pathophysiology of CRPS. Immunomodulating medication reduces the manifestation of inflammation by acting on the mediators of inflammation. Therefore, as inflammation is involved in the pathophysiology of CRPS, immunomodulating medication in CRPS patients may prove beneficial.
To describe the current empirical evidence for the efficacy of administering the most commonly used immunomodulating medication (ie, glucocorticoids, tumor necrosis factor-α antagonists, thalidomide, bisphosphonates, and immunoglobulins) in CRPS patients.
PubMed was searched for original articles that investigated CRPS and the use of one of the abovementioned immunomodulating agents.
The search yielded 39 relevant articles: from these, information on study design, sample size, duration of disease, type and route of medication, primary outcome measures, and results was examined.
Theoretically, the use of immunomodulating medication could counteract the ongoing inflammation and might be an important step in improving a disabled hand or foot, leading to further recovery. However, more high-quality intervention studies are needed.
J Pain. 2012 Aug;13(8):784-9. doi: 10.1016/j.jpain.2012.05.003. Epub 2012 Jul 12.
Genetic HLA associations in complex regional pain syndrome with and without dystonia.
van Rooijen DE, Roelen DL, Verduijn W, Haasnoot GW, Huygen FJ, Perez RS, Claas FH, Marinus J, van Hilten JJ, van den Maagdenberg AM.
Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.
We previously showed evidence for a genetic association of the human leukocyte antigen (HLA) system and complex regional pain syndrome (CRPS) with dystonia. Involvement of the HLA system suggests that CRPS has a genetic component with perturbed regulation of inflammation and neuroplasticity as possible disease mechanisms. However, it is at present unclear whether the observed association with HLA-B62 and HLA-DQ8 in CRPS patients with dystonia also holds true for patients without dystonia. Therefore, we tested the possible association with HLA-B62 and HLA-DQ8 in a clinically homogeneous group of 131 CRPS patients without dystonia. In addition, we investigated the possible association with other alleles of the HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ loci. We showed an increased prevalence of HLA-DQ8 (molecularly typed as HLA-DQB1*03:02; OR = 1.65 [95% CI 1.12-2.42], P = .014) in CRPS without dystonia, whereas no association was observed for HLA-B62 (molecularly typed as HLA-B*15:01; OR = 1.22 [95% CI .78-1.92], P = .458). Our data suggest that CRPS with and CRPS without dystonia may be genetically different, but overlapping, disease entities because only HLA-DQ8 is associated with both. The findings also indicate that distinct biological pathways may play a role in both CRPS subtypes. PERSPECTIVE: This study is the first to replicate a specific HLA region conferring genetic risk for the development of CRPS. Moreover, associations of HLA-DQ8 with both CRPS with and CRPS without dystonia, and HLA-B62 only with CRPS with dystonia, suggest that these disease entities may be genetically different, but overlapping.
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