CRPS March literature review

Neurology. 2011 Sep 13;77(11):1096-101. Epub 2011 Aug 31.

Bilateral somatosensory cortex disinhibition in complex regional pain syndrome type I.

Department of Neurology, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH, Ruhr-University Bochum, Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany. melanie.lenz@rub.de

Abstract

In a previous study, we found bilateral disinhibition in the motor cortex of patients with complex regional pain syndrome (CRPS). This finding suggests a complex dysfunction of central motor-sensory circuits. The aim of our present study was to assess possible bilateral excitability changes in the somatosensory system of patients with CRPS.

We measured paired-pulse suppression of somatosensory evoked potentials in 21 patients with unilateral CRPS I involving the hand. Eleven patients with upper limb pain of non-neuropathic origin and 21 healthy subjects served as controls. Innocuous paired-pulse stimulation of the median nerve was either performed at the affected and the unaffected hand, or at the dominant hand of healthy controls, respectively.

We found a significant reduction of paired-pulse suppression in both sides of patients with CRPS, compared with control patients and healthy control subjects.

These findings resemble our findings in the motor system and strongly support the hypothesis of a bilateral complex impairment of central motor-sensory circuits in CRPS I.

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Anesthesiology. 2012 Feb 15. [Epub ahead of print]

Substance P Signaling Controls Mast Cell Activation, Degranulation, and Nociceptive Sensitization in a Rat Fracture Model of Complex Regional Pain Syndrome.

Abstract

Patients with complex regional pain syndrome have increased tryptase in the skin of the affected extremity indicating mast cell (MC) accumulation and degranulation, processes known to be mediated by substance P (SP). The dysregulation of SP release from primary afferent neurons is characteristic of complex regional pain syndrome. The authors hypothesized that SP acting through the neurokinin-1 receptor results in mast cell accumulation, degranulation, and nociceptive sensitization in a rat model of complex regional pain syndrome.

Groups of 6-10 rats underwent tibia fracture and hind limb casting for 4 weeks, and the hind paw skin was harvested for histologic and immunohistochemical analysis. The effects of a selective neurokinin-1 receptor antagonist (LY303870) and of direct SP intraplantar injection were measured. Dermal MC degranulation induced by sciatic nerve stimulation and the effects of LY303870 on this process were investigated. Finally, the antinociceptive effects of acute and chronic treatment with a MC degranulator (48/80) were tested.

The authors observed that fracture caused MC accumulation, activation, and degranulation, which were inhibited by LY303870; the percentage of MCs in close proximity to peptidergic nerve fibers increased after fracture; electrical stimulation caused MC activation and degranulation, which was blocked by LY303870; intraplantar SP-induced MC degranulation and acute administration of 48/80 caused MC degranulation and enhanced postfracture nociception, but MC-depleted animals showed less sensitization.

These results indicate that facilitated peptidergic neuron-MC signaling after fracture can cause MC accumulation, activation, and degranulation in the injured limb, resulting in nociceptive sensitization.

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Pain. 2012 Feb 13. [Epub ahead of print]

Motor control in complex regional pain syndrome: A kinematic analysis.

Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.

Abstract

This study evaluated movement velocity, frequency, and amplitude, as well as the number of arrests in three different subject groups, by kinematic analysis of repetitive movements during a finger tapping (FT) task. The most affected hands of 80 patients with complex regional pain syndrome (CRPS) were compared with the most affected hands of 60 patients with Parkinson disease (PD) as well as the nondominant hands of 75 healthy control (HC) subjects. Fifteen seconds of FT with thumb and index finger were recorded by a 60-Hz camera, which allowed the whole movement cycle to be evaluated and the above mentioned movement parameters to be calculated. We found that CRPS patients were slower and tapped with more arrests than the two other groups. Moreover, in comparison with the hands of the HC subjects, the unaffected hands of the CRPS patients were also impaired in these domains. Impairment was not related to pain. Dystonic CRPS patients performed less well than CRPS patients without dystonia. In conclusion, this study shows that voluntary motor control in CRPS patients is impaired at both the affected as well as the unaffected side, pointing at involvement of central motor processing circuits.

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Neuromodulation. 2012 Feb 13. doi: 10.1111/j.1525-1403.2011.00424.x. [Epub ahead of print]

Spinal Cord Stimulation in Complex Regional Pain Syndrome Type I of Less Than 12-Month Duration.

Department of Anesthesiology and Pain Therapy, St Elisabeth Hospital, Tilburg, The Netherlands; Department of Anesthesiology and Pain Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands; Department of Anesthesiology and Multidisciplinary Pain Centre, Hospital Oost-Limburg, Genk, Belgium; Department of Neurology, Maastricht University Medical Centre, Maastricht, The Netherlands; and Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht University Medical Centre, Maastricht, The Netherlands.

Abstract

Introduction:  Complex regional pain syndrome type 1 (CRPS-1) has a 31% probability of becoming chronic. The early use of spinal cord stimulation (SCS) has been recommended as a strategy to prevent chronicity and functional impairment. Methods:  In a prospective study, we treated 74 CRPS-1 patients with a mean disease duration of 17 weeks with standard therapy consisting of physical therapy, topical dimethyl sulfoxide, analgesics, transcutaneous stimulation, and sympathetic blockade. Patients who did not respond to standard therapy were offered a treatment with SCS. In these patients, we investigated the impact on pain, quality of life, and function. Results:  Out of these 74 patients treated with standard therapy, six patients were included for early SCS treatment. The overall mean pain relief after one year was 35%. The mental component of the Short Form 36 improved; however, there was no effect on the physical component. None of the SCS treated patients showed a clear improvement in functional outcome. Discussion:  We conclude that the feasibility of performing a randomized controlled trial on early SCS therapy in CRPS-1 is low because of the good disease improvement with standard therapy in the first year after onset. This study raises questions about the need to use SCS early in the course of CRPS-1 because of the probable lack of additional benefit compared with SCS in chronic CRPS-1.

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Eur J Pain. 2012 Feb;16(2):182-95. doi: 10.1016/j.ejpain.2011.06.016.

Enhanced pain and autonomic responses to ambiguous visual stimuli in chronic Complex Regional Pain Syndrome (CRPS) type I.

Royal National Hospital for Rheumatic Diseases, Upper Borough Walls, Bath, BA1 1RL, UK; University of Bath, Bath, BA2 7AY, UK; Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK.

Abstract

Cortical reorganisation of sensory, motor and autonomic systems can lead to dysfunctional central integrative control. This may contribute to signs and symptoms of Complex Regional Pain Syndrome (CRPS), including pain. It has been hypothesised that central neuroplastic changes may cause afferent sensory feedback conflicts and produce pain. We investigated autonomic responses produced by ambiguous visual stimuli (AVS) in CRPS, and their relationship to pain. Thirty CRPS patients with upper limb involvement and 30 age and sex matched healthy controls had sympathetic autonomic function assessed using laser Doppler flowmetry of the finger pulp at baseline and while viewing a control figure or AVS. Compared to controls, there were diminished vasoconstrictor responses and a significant difference in the ratio of response between affected and unaffected limbs (symmetry ratio) to a deep breath and viewing AVS. While viewing visual stimuli, 33.5% of patients had asymmetric vasomotor responses and all healthy controls had a homologous symmetric pattern of response. Nineteen (61%) CRPS patients had enhanced pain within seconds of viewing the AVS. All the asymmetric vasomotor responses were in this group, and were not predictable from baseline autonomic function. Ten patients had accompanying dystonic reactions in their affected limb: 50% were in the asymmetric sub-group. In conclusion, there is a group of CRPS patients that demonstrate abnormal pain networks interacting with central somatomotor and autonomic integrational pathways.

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J Hand Ther. 2011 Apr-Jun;24(2):164-8; quiz 169. Epub 2011 Feb 9.

Graded motor imagery.

Hand Therapy Consultation Services, Richmond, Vermont 05477, USA. victoria@htcsllc.com

Abstract

New information regarding cortical changes in patients with chronic pain has prompted a reevaluation of the typical “bottom up” treatment for pain, which focuses on peripheral nociceptive stimuli. More recently, increasing considerations for chronic pain are focused from the “top down” cortical central processing perspective. Graded motor imagery (GMI) is one treatment technique from the “top down” paradigm designed to treat chronic pain. This technique attempts to sequentially normalize central processing to remediate chronic pain. This article briefly summarizes the basic components of GMI, targeting complex regional pain in the upper limb, and describes a case where this method was successfully integrated. The initial research and clinical experience is promising and indicates that patients with chronic pain may benefit from using GMI to “retrain the brain.”

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Pain. 2010 May;149(2):296-304. Epub 2010 Mar 31.

Mirrored, imagined and executed movements differentially activate sensorimotor cortex in amputees with and without phantom limb pain.

Department of Clinical and Cognitive Neuroscience, Central Institute of Mental Health, University of Heidelberg, D-68159 Mannheim, Germany. martin.diers@zi-mannheim.de

Abstract

Extended viewing of movements of the intact hand in a mirror as well as motor imagery has been shown to decrease pain in phantom pain patients. We used functional magnetic resonance imaging to assess the neural correlates of mirrored, imagined and executed hand movements in 14 upper extremity amputees – 7 with phantom limb pain (PLP) and 7 without phantom limb pain (non-PLP) and 9 healthy controls (HC). Executed movement activated the contralateral sensorimotor area in all three groups but ipsilateral cortex was only activated in the non-PLP and HC group. Mirrored movements activated the sensorimotor cortex contralateral to the hand seen in the mirror in the non-PLP and the HC but not in the PLP. Imagined movement activated the supplementary motor area in all groups and the contralateral primary sensorimotor cortex in the non-PLP and HC but not in the PLP. Mirror- and movement-related activation in the bilateral sensorimotor cortex in the mirror movement condition and activation in the sensorimotor cortex ipsilateral to the moved hand in the executed movement condition were significantly negatively correlated with the magnitude of phantom limb pain in the amputee group. Further research must identify the causal mechanisms related to mirror treatment, imagined movements or movements of the other hand and associated changes in pain perception.

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Curr Opin Anaesthesiol. 2011 Oct;24(5):524-31.

Phantom limb pain and bodily awareness: current concepts and future directions.

Experimental Neuropsychology Research Unit, Monash University, Clayton, Victoria, Australia. melita.giummarra@monash.edu

Abstract

Phantom pain is a frequent consequence of amputation or deafferentation. There are many possible contributing mechanisms, including stump-related pathology, spinal and cortical changes. Phantom limb pain is notoriously difficult to treat. Continued consideration of the factors associated with phantom pain and its treatment is of utmost importance, not only to advance the scientific knowledge about the experience of the body and neuropathic pain, but also fundamentally to promote efficacious pain management.

This review first discusses the mechanisms associated with phantom pain and summarizes the current treatments. The mechanisms underlying phantom pain primarily relate to peripheral/spinal dysfunction, and supraspinal and central plasticity in sensorimotor body representations. The most promising methods for managing phantom pain address the maladaptive changes at multiple levels of the neuraxis, for example, complementing pharmacological administration with physical, psychological or behavioural intervention. These supplementary techniques are even efficacious in isolation, perhaps by replacing the absent afferent signals from the amputated limb, thereby restoring disrupted bodily representations.

Ultimately, for optimal patient outcomes, treatments should be both symptom and mechanism targeted.

Body ownership

Here are a few papers looking at this fascinating a relevant area. Our sense of self is clearly affected in many pain states and in other situations when we are under threat. This is an area we address fully as part of our rehabilitation and treatment programmes for CRPS, other chronic pain states and injuries. The loss of a sense of self is underpinned by a range of physiological changes throughout the nervous system and must be re-trained for normal functioning.

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Curr Opin Anaesthesiol. 2011 Oct;24(5):524-31.

Phantom limb pain and bodily awareness: current concepts and future directions.

Source

aExperimental Neuropsychology Research Unit, Monash University, Clayton, Victoria bSansom Institute for Health Research, University of South Australia, Adelaide, South Australia cNeuroscience Research Australia, Randwick, New South Wales, Australia.

Abstract

PURPOSE OF REVIEW:

Phantom pain is a frequent consequence of amputation or deafferentation. There are many possible contributing mechanisms, including stump-related pathology, spinal and cortical changes. Phantom limb pain is notoriously difficult to treat. Continued consideration of the factors associated with phantom pain and its treatment is of utmost importance, not only to advance the scientific knowledge about the experience of the body and neuropathic pain, but also fundamentally to promote efficacious pain management.

RECENT FINDINGS:

This review first discusses the mechanisms associated with phantom pain and summarizes the current treatments. The mechanisms underlying phantom pain primarily relate to peripheral/spinal dysfunction, and supraspinal and central plasticity in sensorimotor body representations. The most promising methods for managing phantom pain address the maladaptive changes at multiple levels of the neuraxis, for example, complementing pharmacological administration with physical, psychological or behavioural intervention. These supplementary techniques are even efficacious in isolation, perhaps by replacing the absent afferent signals from the amputated limb, thereby restoring disrupted bodily representations.

SUMMARY:

Ultimately, for optimal patient outcomes, treatments should be both symptom and mechanism targeted.

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J Physiol. 2011 Jun 15;589(Pt 12):3009-21. Epub 2011 Apr 26.

Proprioceptive signals contribute to the sense of body ownership.

Source

Neuroscience Research Australia, Barker Street, Randwick, Sydney, NSW 2031, Australia.

Abstract

The sense of body ownership, knowledge that parts of our body ‘belong’ to us, is presumably developed using sensory information. Cutaneous signals seem ideal for this and can modify the sense of ownership. For example, an illusion of ownership over an artificial rubber hand can be induced by synchronously stroking both the subject’s hidden hand and a visible artificial hand. Like cutaneous signals, proprioceptive signals (e.g. frommuscle receptors) exclusively signal events occurring in the body, but the influence of proprioceptors on the sense of body ownership is not known. We developed a technique to generate an illusion of ownership over an artificial plastic finger, using movement at the proximal interphalangeal joint as the stimulus. We then examined this illusion in 20 subjects when their index finger was intact and when the cutaneous and joint afferents from the finger had been blocked by local anaesthesia of the digital nerves. Subjects still experienced an illusion of ownership, induced by movement, over the plastic finger when the digital nerves were blocked. This shows that local cutaneous signals are not essential for the illusion and that inputs arising proximally, presumably from receptors in muscles which move the finger, can influence the sense of body ownership. Contrary to other studies, we found no evidence that voluntary movements induce stronger illusions of body ownership than those induced by passive movement. It seems that the congruence of sensory stimuli ismore important to establish body ownership than the presence of multiple sensory signals.

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Neuropsychologia. 2010 Feb;48(3):713-25. Epub 2009 Nov 11.

Crossmodal congruency measures of lateral distance effects on the rubber hand illusion.

Source

Macquarie Centre for Cognitive Science, Macquarie University, Sydney, NSW 2109, Australia. regine.zopf@maccs.mq.edu.au

Abstract

Body ownership for an artificial hand and the perceived position of one’s own hand can be manipulated in the so-called rubber hand illusion. To induce this illusion, typically an artificial hand is placed next to the participant’s body and stroked in synchrony with the real hand, which is hidden from view. Our first aim was to test if the crossmodal congruency task could be used to obtain a measure for the strength of body ownership in the rubber hand illusion. In this speeded location discrimination task participants responded to tactile targets presented to their index or middle finger, while trying to ignore irrelevant visual distracters placed on the artificial hand either on the congruent finger or on the incongruent finger. The difference between performance on congruent and incongruent trials (crossmodal congruency effect, CCE) indicates the amount of multisensory interactions between tactile targets and visual distracters. In order to investigate if changes in body ownership influence the CCE, we manipulated ownership for an artificial hand by synchronous and asynchronous stroking before the crossmodal congruency task (blocked design) in Experiment 1 and during the crossmodal congruency task (interleaved trial-by-trial design) in Experiment 2. Modulations of the CCE by ownership for an artificial hand were apparent in the interleaved trial-by-trial design. These findings suggest that the CCE can be used as an objective measure for body ownership. Secondly, we tested the hypothesis that the lateral spatial distance between the real hand and artificial hand limits the rubber hand illusion. We found no lateral spatial limits for the rubber hand illusion created by synchronous stroking within reaching distances. In conclusion, the sense of ownership seems to be related to modulations of multisensory interactions possibly through peripersonal space mechanisms, and these modulations do not appear to be limited by an increase in distance between artificial hand and real hand.

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Neuropsychologia. 2010 Feb;48(3):703-12. Epub 2009 Oct 9.

My body in the brain: a neurocognitive model of body-ownership.

Source

Department of Psychology, Royal Holloway, University of London, Egham, Surrey, UK. manos.tsakiris@rhul.ac.uk

Abstract

Empirical research on the bodily self has only recently started to investigate how the link between a body and the experience of this body as mine is developed, maintained or disturbed. The Rubber Hand Illusion has been used as a model instance of the normal sense of embodiment to investigate the processes that underpin the experience of body-ownership. This review puts forward a neurocognitive model according to which body-ownership arises as an interaction between current multisensory input and internal models of the body. First, a pre-existing stored model of the body distinguishes between objects that may or may not be part of one’s body. Second, on-line anatomical and postural representations of the body modulate the integration of multisensory information that leads to the recalibration of visual and tactile coordinate systems. Third, the resulting referral of tactile sensation will give rise to the subjective experience of body-ownership. These processes involve a neural network comprised of the right temporoparietal junction which tests the incorporeability of the external object, the secondary somatosensory cortex which maintains an on-line representation of the body, the posterior parietal and ventral premotor cortices which code for the recalibration of the hand-centred coordinate systems, and the right posterior insula which underpins the subjective experience of body-ownership. The experience of body-ownership may represent a critical component of self-specificity as evidenced by the different ways in which multisensory integration in interaction with internal models of the body can actually manipulate important physical and psychological aspects of the self.

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Cereb Cortex. 2007 Oct;17(10):2235-44. Epub 2006 Nov 30.

Neural signatures of body ownership: a sensory network for bodily self-consciousness.

Source

Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London, UK. e.tsakiris@ucl.ac.uk

Abstract

Body ownership refers to the special perceptual status of one’s own body, which makes bodily sensations seem unique to oneself. We studied the neural correlates of body ownership by controlling whether an external object was accepted as part of the body or not. In the rubber hand illusion (RHI), correlated visuotactile stimulation causes a fake hand to be perceived as part of one’s own body. In the present study, we distinguished between the causes (i.e., multisensory stimulation) and the effect (i.e., the feeling of ownership) of the RHI. Participants watched a right or a left rubber hand being touched either synchronously or asynchronously with respect to their own unseen right hand. A quantifiable correlate of the RHI is a shift in the perceived position of the subject’s hand toward the rubber hand. We used positron emission tomography to identify brain areas whose activity correlated with this proprioceptive measure of body ownership. Body ownership was related to activity in the right posterior insula and the right frontal operculum. Conversely, when the rubber hand was not attributed to the self, activity was observed in the contralateral parietal cortex, particularly the somatosensory cortex. These structures form a network that plays a fundamental role in linking current sensory stimuli to one’s own body and thus also in self-consciousness.

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Ann N Y Acad Sci. 2011 Apr;1225:72-82. doi: 10.1111/j.1749-6632.2011.05990.x.

Significance of the insula for the evolution of human awareness of feelings from the body.

Source

Atkinson Research Laboratory, Barrow Neurological Institute, Phoenix, Arizona, USA. bcraig@chw.edu

Abstract

An ascending sensory pathway that underlies feelings from the body, such as cooling or toothache, terminates in the posterior insula. Considerable evidence suggests that this activity is rerepresented and integrated first in the mid-insula and then in the anterior insula. Activation in the anterior insula correlates directly with subjective feelings from the body and, strikingly, with all emotional feelings. These findings appear to signify a posterior-to-anterior sequence of increasingly homeostatically efficient representations that integrate all salient neural activity, culminating in network nodes in the right and left anterior insulae that may be organized asymmetrically in an opponent fashion. The anterior insula has appropriate characteristics to support the proposal that it engenders a cinemascopic model of human awareness and subjectivity. This review presents the author’s views regarding the principles of organization of this system and discusses a possible sequence for its evolution, as well as particular issues of historical interest.

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Brain Struct Funct. 2010 Jun;214(5-6):563-77. Epub 2010 May 29.

The sentient self.

Source

Atkinson Research Laboratory, Barrow Neurological Institute, 350 West Thomas Rd., Phoenix, AZ 85013, USA. bcraig@chw.edu

Abstract

This article addresses the neuroanatomical evidence for a progression of integrative representations of affective feelings from the body that lead to an ultimate representation of all feelings in the bilateral anterior insulae, or “the sentient self.” Evidence for somatotopy in the primary interoceptive sensory cortex is presented, and the organization of the mid-insula and the anterior insula is discussed. Issues that need to be addressed are highlighted. A possible basis for subjectivity in a cinemascopic model of awareness is presented.

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Nat Rev Neurosci. 2009 Jan;10(1):59-70.

How do you feel–now? The anterior insula and human awareness.

Source

Atkinson Research Laboratory, Barrow Neurological Institute, Phoenix, Arizona 85013, USA. bcraig@chw.edu

Abstract

The anterior insular cortex (AIC) is implicated in a wide range of conditions and behaviours, from bowel distension and orgasm, to cigarette craving and maternal love, to decision making and sudden insight. Its function in the re-representation of interoception offers one possible basis for its involvement in all subjective feelings. New findings suggest a fundamental role for the AIC (and the von Economo neurons it contains) in awareness, and thus it needs to be considered as a potential neural correlate of consciousness.

Harry’s Arctic Heroes

This was inspirational viewing. We watched these guys make their way to the North Pole across the most challenging terrain but also facing up to their own difficulties. The team bond made you want to be there. The way in which they individually dealt with the obstacles, both mental and physical, was a real lesson in the power of thought and character. No more to be said by me, just watch: http://www.bbc.co.uk/i/b013y230/