Is the brain of complex regional pain syndrome patients truly different?

AbstractComplex regional pain syndrome (CRPS) is a common poststroke complication. However, the neural substrates associated with CRPS remain unclear. We investigated the neural correlates associated with poststroke CRPS using voxel-based lesion‒symptom mapping (VLSM) analysis. Among 145 patients with ischemic stroke, 35 were diagnosed with CRPS and categorized into the poststroke CRPS group, and the remaining 110 into the control group. We compared the clinical characteristics between the groups. VLSM analysis was performed to identify the brain region associated with the development of poststroke CRPS. The clinical findings suggested that the poststroke CRPS group had lower muscle strength; lower scores on Fugl‒Meyer assessment, Manual Function Test, Mini-Mental Status Examination; and higher incidence of absent somatosensory evoked potentials in the median nerve than the control group. The head of the caudate nucleus, putamen, and white matter complexes in the corona radiata were significantly associated with poststroke CRPS development in ischemic stroke patients. These results facilitate an understanding of poststroke CRPS pathophysiology. Monitoring patients with lesions in these structures may aid the prevention and early treatment of poststroke CRPS.

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An Update on the Pathophysiology of Complex Regional Pain Syndrome

Anesthesiology ◽

10.1097/aln.0b013e3181e3db38 ◽

2010 ◽

Vol 113 (3) ◽

pp. 713-725 ◽

Cited By ~ 83

Author(s):

Stephen Bruehl ◽

David S. Warner

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Complex Regional Pain Syndrome ◽

Genetic Factors ◽

Pain Syndrome ◽

The Past ◽

Poor Understanding ◽

The Brain ◽

Over Time ◽

Pathophysiologic Mechanisms

Complex regional pain syndrome (CRPS) is a neuropathic pain disorder with significant autonomic features. Few treatments have proven effective, in part, because of a historically poor understanding of the mechanisms underlying the disorder. CRPS research largely conducted during the past decade has substantially increased knowledge regarding its pathophysiologic mechanisms, indicating that they are multifactorial. Both peripheral and central nervous system mechanisms are involved. These include peripheral and central sensitization, inflammation, altered sympathetic and catecholaminergic function, altered somatosensory representation in the brain, genetic factors, and psychophysiologic interactions. Relative contributions of the mechanisms underlying CRPS may differ across patients and even within a patient over time, particularly in the transition from "warm CRPS" (acute) to "cold CRPS" (chronic). Enhanced knowledge regarding the pathophysiology of CRPS increases the possibility of eventually achieving the goal of mechanism-based CRPS diagnosis and treatment.

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Complex Regional Pain Syndrome. A Comprehensive Review on Neuroplastic Changes Supporting the Use of Non-invasive Neurostimulation in Clinical Settings

Frontiers in Pain Research ◽

10.3389/fpain.2021.732343 ◽

2021 ◽

Vol 2 ◽

Author(s):

Andrea Zangrandi ◽

Fannie Allen Demers ◽

Cyril Schneider

Keyword(s):

Complex Regional Pain Syndrome ◽

Pain Syndrome ◽

Current Evidence ◽

Clinical Settings ◽

Non Invasive ◽

The Central Nervous System ◽

Spinal Roots ◽

Invasive Neurostimulation ◽

Future Work ◽

The Brain

Background: Complex regional pain syndrome (CRPS) is a rare debilitating disorder characterized by severe pain affecting one or more limbs. CRPS presents a complex multifactorial physiopathology. The peripheral and sensorimotor abnormalities reflect maladaptive changes of the central nervous system. These changes of volume, connectivity, activation, metabolism, etc., could be the keys to understand chronicization, refractoriness to conventional treatment, and developing more efficient treatments.Objective: This review discusses the use of non-pharmacological, non-invasive neurostimulation techniques in CRPS, with regard to the CRPS physiopathology, brain changes underlying chronicization, conventional approaches to treat CRPS, current evidence, and mechanisms of action of peripheral and brain stimulation.Conclusion: Future work is warranted to foster the evidence of the efficacy of non-invasive neurostimulation in CRPS. It seems that the approach has to be individualized owing to the integrity of the brain and corticospinal function. Non-invasive neurostimulation of the brain or of nerve/muscles/spinal roots, alone or in combination with conventional therapy, represents a fertile ground to develop more efficient approaches for pain management in CRPS.

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IS MIGRAINE A COMPLEX REGIONAL PAIN SYNDROME OF THE BRAIN? MIGRAINE PROPHYLAXIS WITH VITAMIN C?

Pain Practice ◽

10.1111/j.1533-2500.2011.00442.x ◽

2011 ◽

Vol 11 (2) ◽

pp. 199-200 ◽

Cited By ~ 6

Author(s):

Eric J. Visser

Keyword(s):

Vitamin C ◽

Complex Regional Pain Syndrome ◽

Pain Syndrome ◽

Migraine Prophylaxis ◽

The Brain

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A Historical Review of Complex Regional Pain Syndrome in the “Guides Library”

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2009.novdec01 ◽

2009 ◽

Vol 14 (6) ◽

pp. 1-9

Author(s):

Robert J. Barth

Keyword(s):

Differential Diagnosis ◽

Complex Regional Pain Syndrome ◽

Reflex Sympathetic Dystrophy ◽

International Association ◽

Historical Review ◽

Pain Syndrome ◽

Sixth Edition

Abstract Complex regional pain syndrome (CRPS) is a controversial, ambiguous, unreliable, and unvalidated concept that, for these very reasons, has been justifiably ignored in the “AMA Guides Library” that includes the AMAGuides to the Evaluation of Permanent Impairment (AMA Guides), the AMA Guides Newsletter, and other publications in this suite. But because of the surge of CRPS-related medicolegal claims and the mission of the AMA Guides to assist those who adjudicate such claims, a discussion of CRPS is warranted, especially because of what some believe to be confusing recommendations regarding causation. In 1994, the International Association for the Study of Pain (IASP) introduced a newly invented concept, CRPS, to replace the concepts of reflex sympathetic dystrophy (replaced by CRPS I) and causalgia (replaced by CRPS II). An article in the November/December 1997 issue of The Guides Newsletter introduced CRPS and presciently recommended that evaluators avoid the IASP protocol in favor of extensive differential diagnosis based on objective findings. A series of articles in The Guides Newsletter in 2006 extensively discussed the shortcomings of CRPS. The AMA Guides, Sixth Edition, notes that the inherent lack of injury-relatedness for the nonvalidated concept of CRPS creates a dilemma for impairment evaluators. Focusing on impairment evaluation and not on injury-relatedness would greatly simplify use of the AMA Guides.

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Peripheral Nerve and Brachial Plexus Impairment, AMA Guides, Sixth Edition

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2017.marapr01 ◽

2017 ◽

Vol 22 (2) ◽

pp. 3-5

Author(s):

James B. Talmage ◽

Jay Blaisdell

Keyword(s):

Peripheral Nerve ◽

Brachial Plexus ◽

Complex Regional Pain Syndrome ◽

Lower Extremities ◽

Pain Syndrome ◽

Upper Extremities ◽

Motor Deficits ◽

Type I ◽

Sixth Edition ◽

Nerve Entrapments

Abstract Physicians use a variety of methodologies within the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, to rate nerve injuries depending on the type of injury and location of the nerve. Traumatic injuries that cause impairment to the peripheral or brachial plexus nerves are rated using Section 15.4e, Peripheral Nerve and Brachial Plexus Impairment, for upper extremities and Section 16.4c, Peripheral Nerve Rating Process, for lower extremities. Verifiable nerve lesions that incite the symptoms of complex regional pain syndrome, type II (similar to the former concept of causalgia), also are rated in these sections. Nerve entrapments, which are not isolated traumatic events, are rated using the methodology in Section 15.4f, Entrapment Neuropathy. Type I complex regional pain syndrome is rated using Section 15.5, Complex Regional Pain Syndrome for upper extremities or Section 16.5, Complex Regional Pain Syndrome for lower extremities. The method for grading the sensory and motor deficits is analogous to the method described in previous editions of AMA Guides. Rating the permanent impairment of the peripheral nerves or brachial plexus is similar to the methodology used in the diagnosis-based impairment scheme with the exceptions that the physical examination grade modifier is never used to adjust the default rating and the names of individual nerves or plexus trunks, as opposed to the names of diagnoses, appear in the far left column of the rating grids.

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Challenges in the Diagnostic Conceptualization of CRPS-1 (Formerly Conceptualized as RSD)

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2006.marapr01 ◽

2006 ◽

Vol 11 (2) ◽

pp. 1-3, 9-12

Author(s):

Robert J. Barth ◽

Tom W. Bohr

Keyword(s):

Clinical Practice ◽

Complex Regional Pain Syndrome ◽

Somatoform Disorders ◽

International Association ◽

Pain Syndrome ◽

Somatoform Disorder ◽

Syndrome Type ◽

Previous Issue

Abstract From the previous issue, this article continues a discussion of the potentially confusing aspects of the diagnostic formulation for complex regional pain syndrome type 1 (CRPS-1) proposed by the International Association for the Study of Pain (IASP), the relevance of these issues for a proposed future protocol, and recommendations for clinical practice. IASP is working to resolve the contradictions in its approach to CRPS-1 diagnosis, but it continues to include the following criterion: “[c]ontinuing pain, which is disproportionate to any inciting event.” This language only perpetuates existing issues with current definitions, specifically the overlap between the IASP criteria for CRPS-1 and somatoform disorders, overlap with the guidelines for malingering, and self-contradiction with respect to the suggestion of injury-relatedness. The authors propose to overcome the last of these by revising the criterion: “[c]omplaints of pain in the absence of any identifiable injury that could credibly account for the complaints.” Similarly, the overlap with somatoform disorders could be reworded: “The possibility of a somatoform disorder has been thoroughly assessed, with the results of that assessment failing to produce any consistencies with a somatoform scenario.” The overlap with malingering could be addressed in this manner: “The possibility of malingering has been thoroughly assessed, with the results of that assessment failing to produce any consistencies with a malingering scenario.” The article concludes with six recommendations, and a sidebar discusses rating impairment for CRPS-1 (with explicit instructions not to use the pain chapter for this purpose).

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