Review

Authors: Samantha-Su Taylor, Nazir Noor, Ivan Urits...

Complex regional pain syndrome (CRPS) is a chronic pain condition often involving hyperalgesia and allodynia of the extremities. CRPS is divided into CRPS-I and CRPS-II. Type I occurs when there is no confirmed nerve injury. Type II is when there is known associated nerve injury. Female gender is a risk factor for developing CRPS. Other risk factors include fibromyalgia and rheumatoid arthritis. Unfortunately, the pathogenesis of CRPS is not yet clarified. Some studies have demonstrated different potential pathways. Neuropathic inflammation, specifically activation of peripheral nociceptors of C-fibers, has been shown to play a critical role in developing CRPS. The autonomic nervous system (ANS) is involved. Depending on whether it is acute or chronic CRPS, norepinephrine levels are either decreased or increased, respectively. Some studies have suggested the importance of genetics in developing CRPS. More consideration is being given to the role of psychological factors. Some association between a history of depression and/or post-traumatic stress disorder (PTSD) and the diagnosis of CRPS has been demonstrated. Treatment modalities available range from physical therapy, pharmacotherapy, and interventional techniques. Physical and occupational therapies include mirror therapy and graded motor imagery. Medical management with non-steroidal anti-inflammatory drugs (NSAIDs) has not shown significant improvement. There have been supporting findings in the use of short-course steroids, bisphosphonates, gabapentin, and ketamine. Antioxidant treatment has also shown some promise. Other pharmacotherapies include low-dose naltrexone and Botulinum toxin A (BTX-A). Sympathetic blocks are routinely used, even if their short- and long-term effects are not clear. Finally, spinal cord stimulation (SCS) has been used for decades. In conclusion, CRPS is a multifactorial condition that still requires further studying to better understand its pathogenesis, epidemiology, genetic involvement, psychological implications, and treatment options. Future studies are warranted to better understand this syndrome. This will provide an opportunity for better prevention, diagnosis, and treatment of CRPS.

PubMed: 34165690
DOI: 10.1007/s40122-021-00279-4

Review

Authors: Jagan Devarajan, Shayla Mena, Jianguo Cheng...

Complex Regional Pain Syndrome (CRPS) is a chronic pain disorder characterized by a diverse array of symptoms, including pain that is disproportionate to the initial triggering event, accompanied by autonomic, sensory, motor, and sudomotor disturbances. The primary pathology of both types of CRPS (Type I, also known as reflex sympathetic dystrophy, RSD; Type II, also known as causalgia) is featured by allodynia, edema, changes in skin color and temperature, and dystrophy, predominantly affecting extremities. Recent studies started to unravel the complex pathogenic mechanisms of CRPS, particularly from an autoimmune and neuroimmune interaction perspective. CRPS is now recognized as a systemic disease that stems from a complex interplay of inflammatory, immunologic, neurogenic, genetic, and psychologic factors. The relative contributions of these factors may vary among patients and even within a single patient over time. Key mechanisms underlying clinical manifestations include peripheral and central sensitization, sympathetic dysregulation, and alterations in somatosensory processing. Enhanced understanding of the mechanisms of CRPS is crucial for the development of effective therapeutic interventions. While our mechanistic understanding of CRPS remains incomplete, this article updates recent research advancements and sheds light on the etiology, pathogenesis, and molecular underpinnings of CRPS.

PubMed: 38828388
DOI: 10.3389/fpain.2024.1385889

Review

Authors: H Shim, J Rose, S Halle...

Complex regional pain syndrome (CRPS) is a life-altering condition that usually affects the extremities after a trauma or nerve injury. The physiologic changes that occur as a result of the inciting injury are complex, as the name of the syndrome implies. The pain and disability associated with CRPS often lead to psychological co-morbidities that create a vicious cycle of pain, isolation, and depression. We review recent developments in the understanding of CRPS and advancements in management of this syndrome. Further research in targeting specific mechanisms involved in the pathophysiology of CRPS should lead to prevention of this condition.

Topics: Complex Regional Pain Syndromes; Humans

PubMed: 31056241
DOI: 10.1016/j.bja.2019.03.030

Review

Authors: Christina Misidou, Charalampos Papagoras

Complex regional pain syndrome (CRPS) is a perplexing painful syndrome of the extremities usually following a harmful event. It is distinguished in two types, mainly depending on the presence of nerve injury. Although its prevalence may vary depending on social and ethnic factors, middle-aged women seem to suffer most often and the upper limb is the most commonly affected extremity. Apart from pain, which is the dominating feature, the clinical picture unfolds across several domains: sensory, motor, autonomic and trophic. This syndrome develops in two phases, the acute (warm) phase, with the classic symptoms of inflammation, and the chronic (cold) phase, often characterized by trophic changes of the soft tissues and even bones. Although the syndrome has been studied for over two decades, no imaging or laboratory test has been established for the diagnosis and recently proposed diagnostic criteria have not yet been validated and are only occasionally applied. Its pathophysiology is still quite obscure, although the most likely mechanisms involve the classic and neurogenic paths of inflammation mediated by cytokines and neuropeptides, intertwined with changes of the autonomic and central nervous system, psychological mechanisms and, perhaps, autoimmunity. Although plenty of treatment modalities have been tried, none has been proven unequivocally efficacious. Apart from information and education, which should be offered to all patients, the most effective pharmacological treatments seem to be bisphosphonates, glucocorticoids and vasoactive mediators, while physical therapy and rehabilitation therapy also make part of the treatment.

PubMed: 32185338
DOI: 10.31138/mjr.30.1.16

Review

Authors: Yi-Tai Jou

In the last few decades, neurobiological and human brain imaging research have greatly advanced our understanding of brain mechanisms that support perception and memory, as well as their function in daily activities. Knowledge of the neurobiological mechanisms behind the deafferentation of stomatognathic systems has also expanded greatly in recent decades. In particular, current studies reveal that the peripheral deafferentations of stomatognathic systems may be projected globally into the central nervous system (CNS) and become an associated critical factor in triggering and aggravating neurodegenerative diseases. This review explores basic neurobiological mechanisms associated with the deafferentation of stomatognathic systems. Further included is a discussion on tooth loss and other dental deafferentation (DD) mechanisms, with a focus on dental and masticatory apparatuses associated with brain functions and which may underlie the changes observed in the aging brain. A new hypothesis is presented where DD and changes in the functionality of teeth and the masticatory apparatus may cause brain damage as a result of altered cerebral circulation and dysfunctional homeostasis. Furthermore, multiple recurrent reorganizations of the brain may be a triggering or contributing risk factor in the onset and progression of neurodegenerative conditions such as Alzheimer's disease (AD). A growing understanding of the association between DD and brain aging may lead to solutions in treating and preventing cognitive decline and neurodegenerative diseases.

Topics: Aging; Alzheimer Disease; Brain; Causalgia; Cerebrovascular Circulation; Cognitive Dysfunction; Dentition, Permanent; Hearing Loss; Humans; Mastication; Risk Factors; Stomatognathic System; Tooth Loss

PubMed: 29655412
DOI: 10.1016/j.kjms.2018.01.013

Authors: G D Schott

Topics: Autonomic Nerve Block; Causalgia; Guanethidine; Humans; Meta-Analysis as Topic; Pain; Phentolamine; Prospective Studies; Randomized Controlled Trials as Topic; Reflex Sympathetic Dystrophy; Retrospective Studies; Sympatholytics; Treatment Failure

PubMed: 9549444
DOI: 10.1136/bmj.316.7134.792