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Clarke S, Rogers R, Wanigasekera V, Fardo F, Pia H, Nochi Z, Macian N, Leray V, Finnerup NB, Pickering G, Mouraux A, Truini A, Treede RD, Garcia-Larrea L, Tracey I. Systematic review and co-ordinate based meta-analysis to summarize the utilization of functional brain imaging in conjunction with human models of peripheral and central sensitization. Eur J Pain 2024. [PMID: 38381488 DOI: 10.1002/ejp.2251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 01/04/2024] [Accepted: 02/05/2024] [Indexed: 02/22/2024]
Abstract
BACKGROUND AND OBJECTIVE Functional magnetic resonance imaging, in conjunction with models of peripheral and/or central sensitization, has been used to assess analgesic efficacy in healthy humans. This review aims to summarize the use of these techniques to characterize brain mechanisms of hyperalgesia/allodynia and to evaluate the efficacy of analgesics. DATABASES AND DATA TREATMENT Searches were performed (PubMed-Medline, Cochrane, Web of Science and Clinicaltrials.gov) to identify and review studies. A co-ordinate based meta-analysis (CBMA) was conducted to quantify neural activity that was reported across multiple independent studies in the hyperalgesic condition compared to control, using GingerALE software. RESULTS Of 217 publications, 30 studies met the inclusion criteria. They studied nine different models of hyperalgesia/allodynia assessed in the primary (14) or secondary hyperalgesia zone (16). Twenty-three studies focused on neural correlates of hyperalgesic conditions and showed consistent changes in the somatosensory cortex, prefrontal cortices, insular cortex, anterior cingulate cortex, thalamus and brainstem. The CBMA on 12 studies that reported activation coordinates for a contrast comparing the hyperalgesic state to control produced six activation clusters (significant at false discovery rate of 0.05) with more peaks for secondary (17.7) than primary zones (7.3). Seven studies showed modulation of brain activity by analgesics in five of the clusters but also in four additional regions. CONCLUSIONS This meta-analysis revealed substantial but incomplete overlap between brain areas related to neural mechanisms of hyperalgesia and those reflecting the efficacy of analgesic drugs. Studies testing in the secondary zone were more sensitive to evaluate analgesic efficacy on central sensitization at brainstem or thalamocortical levels. SIGNIFICANCE Experimental pain models that provide a surrogate for features of pathological pain conditions in healthy humans and functional imaging techniques are both highly valuable research tools. This review shows that when used together, they provide a wealth of information about brain activity during pain states and analgesia. These tools are promising candidates to help bridge the gap between animal and human studies, to improve translatability and provide opportunities for identification of new targets for back-translation to animal studies.
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Affiliation(s)
- Sophie Clarke
- Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, FMRIB, University of Oxford, Oxford, UK
| | - Richard Rogers
- Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, FMRIB, University of Oxford, Oxford, UK
| | - Vishvarani Wanigasekera
- Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, FMRIB, University of Oxford, Oxford, UK
| | - Francesca Fardo
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark
- Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Hossein Pia
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark
| | - Zahra Nochi
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark
| | - Nicolas Macian
- Platform of Clinical Investigation, Inserm CIC 1405, University Hospital Clermont-Ferrand, Clermont-Ferrand, France
| | - Vincent Leray
- Platform of Clinical Investigation, Inserm CIC 1405, University Hospital Clermont-Ferrand, Clermont-Ferrand, France
| | - Nanna Brix Finnerup
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark
| | - Gisèle Pickering
- Platform of Clinical Investigation, Inserm CIC 1405, University Hospital Clermont-Ferrand, Clermont-Ferrand, France
- Inserm 1107, University Clermont Auvergne, Clermont-Ferrand, France
| | - André Mouraux
- Institute of Neuroscience (IoNS), Université Catholique de Louvain (UCLouvain), Ottignies-Louvain-la-Neuve, Belgium
| | - Andrea Truini
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - Rolf-Detlef Treede
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany
| | - Luis Garcia-Larrea
- NeuroPain Lab, Lyon Centre for Neuroscience Inserm U1028 and University Claude Bernard, Lyon, France
- Pain Center Neurological Hospital (CETD), Hospices Civils de Lyon, Lyon, France
| | - Irene Tracey
- Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, FMRIB, University of Oxford, Oxford, UK
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Wong F, Reddy A, Rho Y, Vollert J, Strutton PH, Hughes SW. Responders and nonresponders to topical capsaicin display distinct temporal summation of pain profiles. Pain Rep 2023; 8:e1071. [PMID: 37731476 PMCID: PMC10508395 DOI: 10.1097/pr9.0000000000001071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 12/15/2022] [Accepted: 02/02/2023] [Indexed: 09/22/2023] Open
Abstract
Introduction Topical application of capsaicin can produce an ongoing pain state in healthy participants. However, approximately one-third report no pain response (ie, nonresponders), and the reasons for this are poorly understood. Objectives In this study, we investigated temporal summation of pain (TSP) profiles, pain ratings and secondary hyperalgesia responses in responders and nonresponders to 1% topical capsaicin cream. Methods Assessments were made at baseline and then during an early (ie, 15 minutes) and late (ie, 45 minutes) time points post-capsaicin in 37 healthy participants. Results Participants reporting a visual analogue scale (VAS) rating of >50 were defined as responders (n = 24) and those with <50 VAS rating were defined as nonresponders (n = 13). There was a facilitation of TSP during the transition from an early to the late time point post-capsaicin (P<0.001) and the development of secondary hyperalgesia (P<0.05) in the responder group. Nonresponders showed no changes in TSP or secondary hyperalgesia during the early and late time points. There was an association between baseline TSP scores and the later development of a responder or nonresponder phenotype (r = 0.36; P = 0.03). Receiver operating characteristic analysis revealed that baseline TSP works as a good response predictor at an individual level (area under the curve = 0.75). Conclusion These data suggest that responders and nonresponders have different facilitatory pain mechanisms. The assessment of TSP may help to identify participants with stronger endogenous pain facilitation who may be more likely to respond to topical capsaicin.
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Affiliation(s)
- Felyx Wong
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Aditi Reddy
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Yeanuk Rho
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Jan Vollert
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Paul H. Strutton
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Sam W. Hughes
- The Pain Modulation Laboratory, Brain Research and Imaging Centre (BRIC), School of Psychology, Faculty of Health, University of Plymouth, Plymouth, United Kingdom
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Louzolo A, Almeida R, Guitart-Masip M, Björnsdotter M, Lebedev A, Ingvar M, Olsson A, Petrovic P. Enhanced Instructed Fear Learning in Delusion-Proneness. Front Psychol 2022; 13:786778. [PMID: 35496229 PMCID: PMC9043131 DOI: 10.3389/fpsyg.2022.786778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/04/2022] [Indexed: 11/20/2022] Open
Abstract
Psychosis is associated with distorted perceptions and deficient bottom-up learning such as classical fear conditioning. This has been interpreted as reflecting imprecise priors in low-level predictive coding systems. Paradoxically, overly strong beliefs, such as overvalued beliefs and delusions, are also present in psychosis-associated states. In line with this, research has suggested that patients with psychosis and associated phenotypes rely more on high-order priors to interpret perceptual input. In this behavioural and fMRI study we studied two types of fear learning, i.e., instructed fear learning mediated by verbal suggestions about fear contingencies and classical fear conditioning mediated by low level associative learning, in delusion proneness—a trait in healthy individuals linked to psychotic disorders. Subjects were shown four faces out of which two were coupled with an aversive stimulation (CS+) while two were not (CS-) in a fear conditioning procedure. Before the conditioning, subjects were informed about the contingencies for two of the faces of each type, while no information was given for the two other faces. We could thereby study the effect of both classical fear conditioning and instructed fear learning. Our main outcome variable was evaluative rating of the faces. Simultaneously, fMRI-measurements were performed to study underlying mechanisms. We postulated that instructed fear learning, measured with evaluative ratings, is stronger in psychosis-related phenotypes, in contrast to classical fear conditioning that has repeatedly been shown to be weaker in these groups. In line with our hypothesis, we observed significantly larger instructed fear learning on a behavioural level in delusion-prone individuals (n = 20) compared to non-delusion-prone subjects (n = 23; n = 20 in fMRI study). Instructed fear learning was associated with a bilateral activation of lateral orbitofrontal cortex that did not differ significantly between groups. However, delusion-prone subjects showed a stronger functional connectivity between right lateral orbitofrontal cortex and regions processing fear and pain. Our results suggest that psychosis-related states are associated with a strong instructed fear learning in addition to previously reported weak classical fear conditioning. Given the similarity between nocebo paradigms and instructed fear learning, our results also have an impact on understanding why nocebo effects differ between individuals.
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Affiliation(s)
- Anaïs Louzolo
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Rita Almeida
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Marc Guitart-Masip
- Department of Neurobiology, Care Science and Society, Karolinska Institutet, Stockholm, Sweden
| | - Malin Björnsdotter
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Alexander Lebedev
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Martin Ingvar
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Andreas Olsson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Predrag Petrovic
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Brazenor GA, Malham GM, Teddy PJ. Can Central Sensitization after injury persist as an autonomous pain generator? - A comprehensive search for evidence. PAIN MEDICINE 2021; 23:1283-1298. [PMID: 34718773 DOI: 10.1093/pm/pnab319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 10/11/2021] [Accepted: 10/21/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To conduct a comprehensive search for evidence whether Central Sensitization following an injury can act as a persistent autonomous pain generator after the inducing injury has healed. METHODS We searched Medline on PubMed and the Cochrane Library, screening 3,572 abstracts, from which 937 full text articles were obtained, with 186 of these discarded as irrelevant to the question being posed. The remaining 751 articles were studied for evidence. RESULTS Fourteen publications were judged to provide weak evidence for the hypothesis of central sensitization as a persisting autonomous pain generator, but none addressed the question directly. No strong evidence for the affirmative answer was found.Sixty-two publications were judged to provide weak evidence for a negative answer, and nine judged to provide strong evidence.Unexpectedly, serious weaknesses were discovered in the literature underpinning the validity of the clinical diagnosis of Central Sensitization in man:(i) Inappropriate extrapolation, in many publications, of laboratory animal data to humans.(ii) Failure to demonstrate the absence of peripheral pain generators which might be perpetuating Central Sensitization.(iii) Many factors now shown to confound what is being measured by quantitative sensory testing, conditioned pain modulation, and Central Sensitization Inventory. CONCLUSIONS We found no evidence proving that central sensitization can persist as an autonomous pain generator after the initiating injury has healed.Our review has also shown that the evidential basis for the diagnosis of CS in individual patients is seriously in question.
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Affiliation(s)
| | | | - Peter J Teddy
- Royal Melbourne Hospital, Parkville, Victoria, Australia
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Springborg AD, Wessel CR, Andersen LPK, Werner MU. Methodology and applicability of the human contact burn injury model: A systematic review. PLoS One 2021; 16:e0254790. [PMID: 34329326 PMCID: PMC8323928 DOI: 10.1371/journal.pone.0254790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 07/06/2021] [Indexed: 11/24/2022] Open
Abstract
The contact burn injury model is an experimental contact thermode-based physiological pain model primarily applied in research of drug efficacy in humans. The employment of the contact burn injury model across studies has been inconsistent regarding essential methodological variables, challenging the validity of the model. This systematic review analyzes methodologies, outcomes, and research applications of the contact burn injury model. Based on these results, we propose an improved contact burn injury testing paradigm. A literature search was conducted (15-JUL-2020) using PubMed, EMBASE, Web of Science, and Google Scholar. Sixty-four studies were included. The contact burn injury model induced consistent levels of primary and secondary hyperalgesia. However, the analyses revealed variations in the methodology of the contact burn injury heating paradigm and the post-burn application of test stimuli. The contact burn injury model had limited testing sensitivity in demonstrating analgesic efficacy. There was a weak correlation between experimental and clinical pain intensity variables. The data analysis was limited by the methodological heterogenicity of the different studies and a high risk of bias across the studies. In conclusion, although the contact burn injury model provides robust hyperalgesia, it has limited efficacy in testing analgesic drug response. Recommendations for future use of the model are being provided, but further research is needed to improve the sensitivity of the contact burn injury method. The protocol for this review has been published in PROSPERO (ID: CRD42019133734).
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Affiliation(s)
- Anders Deichmann Springborg
- Department of Anesthesia, Multidisciplinary Pain Center, Pain and Respiratory Support, Neuroscience Center, Copenhagen University Hospital, Copenhagen, Denmark
- * E-mail:
| | - Caitlin Rae Wessel
- Department of Physiology, University of Kentucky, Lexington, KY, United States of America
| | - Lars Peter Kloster Andersen
- Department of Anaesthesia and Intensive Care, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Mads Utke Werner
- Department of Anesthesia, Multidisciplinary Pain Center, Pain and Respiratory Support, Neuroscience Center, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Sciences, Lund University, Lund, Sweden
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Springborg AD, Jensen EK, Kreilgaard M, Petersen MA, Papathanasiou T, Lund TM, Taylor BK, Werner MU. High-dose naloxone: Effects by late administration on pain and hyperalgesia following a human heat injury model. A randomized, double-blind, placebo-controlled, crossover trial with an enriched enrollment design. PLoS One 2020; 15:e0242169. [PMID: 33180816 PMCID: PMC7660513 DOI: 10.1371/journal.pone.0242169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/27/2020] [Indexed: 11/18/2022] Open
Abstract
Severe chronic postsurgical pain has a prevalence of 4–10% in the surgical population. The underlying nociceptive mechanisms have not been well characterized. Following the late resolution phase of an inflammatory injury, high-dose μ-opioid-receptor inverse agonists reinstate hypersensitivity to nociceptive stimuli. This unmasking of latent pain sensitization has been a consistent finding in rodents while only observed in a limited number of human volunteers. Latent sensitization could be a potential triggering venue in chronic postsurgical pain. The objective of the present trial was in detail to examine the association between injury-induced secondary hyperalgesia and naloxone-induced unmasking of latent sensitization. Healthy volunteers (n = 80) received a cutaneous heat injury (47°C, 420 s, 12.5 cm2). Baseline secondary hyperalgesia areas were assessed 1 h post-injury. Utilizing an enriched enrollment design, subjects with a magnitude of secondary hyperalgesia areas in the upper quartile (‘high-sensitizers’ [n = 20]) and the lower quartile (‘low-sensitizers’ [n = 20]) were selected for further study. In four consecutive experimental sessions (Sessions 1 to 4), the subjects at two sessions (Sessions 1 and 3) received a cutaneous heat injury followed 168 h later (Sessions 2 and 4) by a three-step target-controlled intravenous infusion of naloxone (3.25 mg/kg), or normal saline. Assessments of secondary hyperalgesia areas were made immediately before and stepwise during the infusions. Simple univariate statistics revealed no significant differences in secondary hyperalgesia areas between naloxone and placebo treatments (P = 0.215), or between ‘high-sensitizers’ and ‘low-sensitizers’ (P = 0.757). In a mixed-effects model, secondary hyperalgesia areas were significantly larger following naloxone as compared to placebo for ‘high-sensitizers’ (P < 0.001), but not ‘low-sensitizers’ (P = 0.651). Although we could not unequivocally demonstrate naloxone-induced reinstatement of heat injury-induced hyperalgesia, further studies in clinical postsurgical pain models are warranted.
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Affiliation(s)
| | | | - Mads Kreilgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Aagaard Petersen
- The Research Unit, Department of Palliative Medicine, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Theodoros Papathanasiou
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Trine Meldgaard Lund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bradley Kenneth Taylor
- Department of Anesthesiology, Pittsburgh Center for Pain Research, and the Pittsburgh Project to End Opioid Misuse, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Mads Utke Werner
- Neuroscience Center, Copenhagen University Hospitals, Copenhagen, Denmark
- Department of Clinical Sciences, Lund University, Lund, Sweden
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Hughes SW, Basra M, Chan C, Parr C, Wong F, Gomes S, Strutton PH. Capsaicin-Induced Changes in Electrical Pain Perception Threshold Can Be Used to Assess the Magnitude of Secondary Hyperalgesia in Humans. PAIN MEDICINE 2020; 21:2830-2838. [DOI: 10.1093/pm/pnaa082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Abstract
Objectives
Areas of secondary hyperalgesia can be assessed using quantitative sensory testing (QST). Delivering noxious electrocutaneous stimulation could provide added benefit by allowing multiple measurements of the magnitude of hyperalgesia. We aimed to characterize the use of electrical pain perception (EPP) thresholds alongside QST as a means by which to measure changes in pain thresholds within an area of secondary mechanical hyperalgesia.
Methods
EPP and heat pain thresholds (HPTs) were measured at five distinct points at baseline and following 1% capsaicin cream application, one within a central zone and four within a secondary zone. Areas of secondary mechanical hyperalgesia were mapped using QST. In a further 14 participants, capsaicin-induced reduction in EPP thresholds was mapped using a radial lines approach across 24 points.
Results
There was a reduction in EPP threshold measured at the four points within the secondary zone, which was within the mapped area of mechanical secondary hyperalgesia. The magnitude of secondary hyperalgesia could be split into a mild (∼4% reduction) and severe (∼21% reduction) area within an individual subject. There was no reduction in HPT within the secondary zone, but there was a reduction in both HPT and EPP threshold within the primary zone. EPP mapping revealed differences in the magnitude and spread of hyperalgesia across all subjects.
Conclusions
Measuring capsaicin-induced reduction in EPP thresholds can be used to map hyperalgesic areas in humans. This semi-automated approach allows rapid assessment of the magnitude of hyperalgesia, both within an individual subject and across a study population.
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Affiliation(s)
- Sam W Hughes
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Meirvaan Basra
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Calvin Chan
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Callum Parr
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Felyx Wong
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Sofia Gomes
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
| | - Paul H Strutton
- Division of Surgery, Department of Surgery and Cancer, The Nick Davey Laboratory, Faculty of Medicine, Imperial College London, London, UK
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8
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Wahl AM, Bidstrup D, Smidt-Nielsen IG, Werner MU, Hyldegaard O, Rotbøll-Nielsen P. A single session of hyperbaric oxygen therapy demonstrates acute and long-lasting neuroplasticity effects in humans: a replicated, randomized controlled clinical trial. J Pain Res 2019; 12:2337-2348. [PMID: 31534358 PMCID: PMC6682324 DOI: 10.2147/jpr.s198359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/24/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose Animal studies have demonstrated anti-inflammatory, and anti-nociceptive properties of hyperbaric oxygen therapy (HBOT). However, physiological data are scarce in humans. In a recent experimental study, the authors used the burn injury (BI) model observing a decrease in secondary hyperalgesia areas (SHA) in the HBOT-group compared to a control-group. Surprisingly, a long-lasting neuroplasticity effect mitigating the BI-induced SHA-response was seen in the HBOT-preconditioned group. The objective of the present study, therefore, was to confirm our previous findings using an examiner-blinded, block-randomized, controlled, crossover study design. Patients and methods Nineteen healthy subjects attended two BI-sessions with an inter-session interval of ≥28 days. The BIs were induced on the lower legs by a contact thermode (12.5 cm2, 47C°, 420 s). The subjects were block-randomized to receive HBOT (2.4 ATA, 100% O2, 90 min) or ambient conditions ([AC]; 1 ATA, 21% O2), dividing cohorts equally into two sequence allocations: HBOT-AC or AC-HBOT. All sensory assessments performed during baseline, BI, and post-intervention phases were at homologous time points irrespective of sequence allocation. The primary outcome was SHA, comparing interventions and sequence allocations. Results Data are mean (95% CI). During HBOT-sessions a mitigating effect on SHA was demonstrated compared to AC-sessions, ie, 18.8 (10.5–27.0) cm2 vs 32.0 (20.1–43.9) cm2 (P=0.021), respectively. In subjects allocated to the sequence AC-HBOT a significantly larger mean difference in SHA in the AC-session vs the HBOT-session was seen 25.0 (5.4–44.7) cm2 (P=0.019). In subjects allocated to the reverse sequence, HBOT-AC, no difference in SHA between sessions was observed (P=0.55), confirming a preconditioning, long-lasting (≥28 days) effect of HBOT. Conclusion Our data demonstrate that a single HBOT-session compared to control is associated with both acute and long-lasting mitigating effects on BI-induced SHA, confirming central anti-inflammatory, neuroplasticity effects of hyperbaric oxygen therapy.
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Affiliation(s)
- Anna M Wahl
- Hyperbaric Unit, Department of Anesthesia, Head and Orthopedic Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Daniel Bidstrup
- Hyperbaric Unit, Department of Anesthesia, Head and Orthopedic Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Isabel G Smidt-Nielsen
- Hyperbaric Unit, Department of Anesthesia, Head and Orthopedic Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Mads U Werner
- Multidisciplinary Pain Center, Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Ole Hyldegaard
- Hyperbaric Unit, Department of Anesthesia, Head and Orthopedic Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Per Rotbøll-Nielsen
- Multidisciplinary Pain Center, Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark
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Hansen MS, Becerra L, Dahl JB, Borsook D, Mårtensson J, Christensen A, Nybing JD, Havsteen I, Boesen M, Asghar MS. Brain resting-state connectivity in the development of secondary hyperalgesia in healthy men. Brain Struct Funct 2019; 224:1119-1139. [PMID: 30631932 DOI: 10.1007/s00429-018-01819-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 12/16/2018] [Indexed: 01/25/2023]
Abstract
Central sensitization is a condition in which there is an abnormal responsiveness to nociceptive stimuli. As such, the process may contribute to the development and maintenance of pain. Factors influencing the propensity for development of central sensitization have been a subject of intense debate and remain elusive. Injury-induced secondary hyperalgesia can be elicited by experimental pain models in humans, and is believed to be a result of central sensitization. Secondary hyperalgesia may thus reflect the individual level of central sensitization. The objective of this study was to investigate possible associations between increasing size of secondary hyperalgesia area and brain connectivity in known resting-state networks. We recruited 121 healthy participants (male, age 22, SD 3.35) who underwent resting-state functional magnetic resonance imaging. Prior to the scan session, areas of secondary hyperalgesia following brief thermal sensitization (3 min. 45 °C heat stimulation) were evaluated in all participants. 115 participants were included in the final analysis. We found a positive correlation (increasing connectivity) with increasing area of secondary hyperalgesia in the sensorimotor- and default mode networks. We also observed a negative correlation (decreasing connectivity) with increasing secondary hyperalgesia area in the sensorimotor-, fronto-parietal-, and default mode networks. Our findings indicate that increasing area of secondary hyperalgesia is associated with increasing and decreasing connectivity in multiple networks, suggesting that differences in the propensity for central sensitization, assessed as secondary hyperalgesia areas, may be expressed as differences in the resting-state central neuronal activity.
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Affiliation(s)
- Morten Sejer Hansen
- Department of Anaesthesiology, 4231, Centre of Head and Orthopaedics, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark.
| | - Lino Becerra
- Invicro, A Konica Minolta Company, 27 Drydock Avenue, 7th Floor West, Boston, MA, 02210, USA
| | - Jørgen Berg Dahl
- Department of Anaesthesiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark
| | - David Borsook
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Boston, MA, USA
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Johan Mårtensson
- Department of Clinical Sciences, Faculty of Medicine, Lund University, Box 213, 221 00, Lund, Sweden
| | - Anders Christensen
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark
| | - Janus Damm Nybing
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark
| | - Inger Havsteen
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark
| | - Mikael Boesen
- Department of Radiology and the Parker Institute, Copenhagen University Hospital Bispebjerg and Frederiksberg, Bispebjerg Hospital, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark
| | - Mohammad Sohail Asghar
- Department of Neuroanaesthesiology, Neurocentre, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
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Hansen MS, Asghar MS, Wetterslev J, Pipper CB, Mårtensson J, Becerra L, Christensen A, Nybing JD, Havsteen I, Boesen M, Dahl JB. The association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other pain relevant brain structures-A 3-tesla MRI study of healthy men. PLoS One 2018; 13:e0201642. [PMID: 30130373 PMCID: PMC6103511 DOI: 10.1371/journal.pone.0201642] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 07/19/2018] [Indexed: 12/12/2022] Open
Abstract
Introduction Central sensitization plays a pivotal role in maintenance of pain and is believed to be intricately involved in several chronic pain conditions. One clinical manifestation of central sensitization is secondary hyperalgesia. The degree of secondary hyperalgesia presumably reflects individual levels of central sensitization. The objective of this study was to investigate the association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other brain structures involved in pain processing. Materials and methods We recruited 121 healthy male participants; 118 were included in the final analysis. All participants underwent whole brain magnetic resonance imaging (MRI). Prior to MRI, all participants underwent pain testing. Secondary hyperalgesia was induced by brief thermal sensitization. Additionally, we recorded heat pain detection thresholds (HPDT), pain during one minute thermal stimulation (p-TS) and results of the Pain Catastrophizing Scale (PCS) and Hospital Anxiety and Depression score (HADS). Results We found no significant associations between the size of the area of secondary hyperalgesia and the volume of the caudate nuclei or of the following structures: primary somatosensory cortex, anterior and mid cingulate cortex, putamen, nucleus accumbens, globus pallidus, insula and the cerebellum. Likewise, we found no significant associations between the volume of the caudate nuclei and HPDTs, p-TS, PCS and HADS. Conclusions Our findings indicate that the size of the secondary hyperalgesia area is not associated with the volume of brain structures relevant for pain processing, suggesting that the propensity to develop central sensitization, assessed as secondary hyperalgesia, is not correlated to brain structure volume.
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Affiliation(s)
- Morten S. Hansen
- Department of Anaesthesiology, Centre of head and orthopaedics, Rigshospitalet, Copenhagen, Denmark
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
- * E-mail:
| | - Mohammad S. Asghar
- Department of Anaesthesiology, Centre of head and orthopaedics, Rigshospitalet, Copenhagen, Denmark
| | - Jørn Wetterslev
- Copenhagen Trial Unit, Centre for Clinical Intervention Research, department, Copenhagen, Denmark
| | - Christian B. Pipper
- Section of Biostatistics, Faculty of health, Copenhagen University, Copenhagen, Denmark
| | - Johan Mårtensson
- Department of Clinical Sciences, Faculty of Medicine, Lund university, Lund, Sweden
| | - Lino Becerra
- Invicro, A Konica Minolta Company, Boston, United States of America
| | - Anders Christensen
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Janus D. Nybing
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Inger Havsteen
- Department of Radiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Mikael Boesen
- Department of Radiology and the Parker Institute, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Jørgen B. Dahl
- Department of Anaesthesiology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
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Grosser T, Theken KN, FitzGerald GA. Cyclooxygenase Inhibition: Pain, Inflammation, and the Cardiovascular System. Clin Pharmacol Ther 2017; 102:611-622. [PMID: 28710775 DOI: 10.1002/cpt.794] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 07/11/2017] [Indexed: 12/26/2022]
Abstract
Inhibitors of the cyclooxygenases (COXs), the nonsteroidal antiinflammatory drugs (NSAIDs), relieve inflammatory pain, but are associated with gastrointestinal and cardiovascular complications. Given the widespread use of NSAIDs, there has been a longstanding interest in optimizing their risk-benefit ratio, for example by reducing their gastrointestinal risk. More recently, the focus has shifted toward the cardiovascular complications of NSAIDs and very large prospective studies have been performed to compare cardiovascular risk across distinct NSAIDs. Surprisingly, much less attention has been paid to the efficacy side of the risk-benefit ratio. There is marked variability in the degree of pain relief by NSAIDs due to the complex interplay of molecular mechanisms contributing to the pain sensation, variability in the disposition of NSAIDs, and imprecision in the quantification of human pain. Here we discuss how NSAIDs relieve pain, how molecular mechanisms relate to clinical efficacy, and how this may inform our interpretation of clinical trials.
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Affiliation(s)
- Tilo Grosser
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Katherine N Theken
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Garret A FitzGerald
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Hansen MS, Wetterslev J, Pipper CB, Asghar MS, Dahl JB. Heat pain detection threshold is associated with the area of secondary hyperalgesia following brief thermal sensitization: a study of healthy male volunteers. J Pain Res 2017; 10:265-274. [PMID: 28184167 PMCID: PMC5291329 DOI: 10.2147/jpr.s121189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Introduction The area of secondary hyperalgesia following brief thermal sensitization (BTS) of the skin and heat pain detection thresholds (HPDT) may both have predictive abilities in regards to pain sensitivity and clinical pain states. The association between HPDT and secondary hyperalgesia, however, remains unsettled, and the dissimilarities in physiologic properties suggest that they may represent 2 distinctively different pain entities. The aim of this study was to investigate the association between HPDT and BTS-induced secondary hyperalgesia. Methods A sample of 121 healthy male participants was included and tested on 2 separate study days with BTS (45°C, 3 minutes), HPDT, and pain during thermal stimulation (45°C, 1 minute). Areas of secondary hyperalgesia were quantified after monofilament pinprick stimulation. The pain catastrophizing scale (PCS) and hospital anxiety and depression scale (HADS) were also applied. Results A significant association between HPDT and the size of the area of secondary hyperalgesia (p<0.0001) was found. The expected change in area of secondary hyperalgesia due to a 1-degree increase in HPDT was estimated to be −27.38 cm2, 95% confidence interval (CI) of −37.77 to −16.98 cm2, with an R2 of 0.19. Likewise, a significant association between HADS-depression subscore and area of secondary hyperalgesia (p=0.046) was found, with an estimated expected change in secondary hyperalgesia to a 1-point increase in HADS-depression subscore of 11 cm2, 95% CI (0.19–21.82), and with R2 of 0.03. We found no significant associations between secondary hyperalgesia area and PCS score or pain during thermal stimulation. Conclusion HPDT and the area of secondary hyperalgesia after BTS are significantly associated; however, with an R2 of only 19%, HPDT only offers a modest explanation of the inter-participant variation in the size of the secondary hyperalgesia area elicited by BTS.
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Affiliation(s)
- Morten Sejer Hansen
- Department of Anesthesiology, 4231, Centre of Head and Orthopedics, Rigshospitalet
| | - Jørn Wetterslev
- Copenhagen Trial Unit, Centre for Clinical Intervention Research, Department 7812
| | | | | | - Jørgen Berg Dahl
- Department of Anesthesiology, Department Z, Bispebjerg Hospital, Copenhagen, Denmark
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Yaksh TL, Fisher CJ, Hockman TM, Wiese AJ. Current and Future Issues in the Development of Spinal Agents for the Management of Pain. Curr Neuropharmacol 2017; 15:232-259. [PMID: 26861470 PMCID: PMC5412694 DOI: 10.2174/1570159x14666160307145542] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 12/02/2015] [Accepted: 02/05/2016] [Indexed: 11/22/2022] Open
Abstract
Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety.
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Affiliation(s)
- Tony L. Yaksh
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Casey J. Fisher
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Tyler M. Hockman
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Ashley J. Wiese
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
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Hirai PM, Thomson OP. T4 syndrome - A distinct theoretical concept or elusive clinical entity? A case report. J Bodyw Mov Ther 2016; 20:722-727. [PMID: 27814850 DOI: 10.1016/j.jbmt.2016.06.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 05/16/2016] [Accepted: 06/01/2016] [Indexed: 11/29/2022]
Abstract
T4 syndrome has existed as a clinical concept for more than three decades and it has been identified as a source of upper extremity (UE) symptoms. This case report explores the clinical reasoning in the diagnoses and management of a patient with symptoms consistent with T4-type syndrome and critically discusses the concept of T4 syndrome using recent research to help explain the clinical presentation. Manual therapy treatment focused on stimulation of the sympathetic ganglia, decreasing local upper thoracic pain and UE referral pattern noted during passive examination. The successful outcomes included immediate and lasting symptom relief after upper thoracic spinal manipulation. Although treatment has been based on the theory that mechanical thoracic dysfunction can produce sympathetic nervous system (SNS) referred pain, the role the sympathetic reflexes potentially plays on the referral symptoms to the UE presently remains unclear.
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Affiliation(s)
- Patricia Miyuki Hirai
- Research Centre, British School of Osteopathy, 275 Borough High Street, London, SE1 1JE, UK
| | - Oliver P Thomson
- Research Centre, British School of Osteopathy, 275 Borough High Street, London, SE1 1JE, UK.
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Hansen MS, Asghar MS, Wetterslev J, Pipper CB, Johan Mårtensson J, Becerra L, Christensen A, Nybing JD, Havsteen I, Boesen M, Dahl JB. Is the Volume of the Caudate Nuclei Associated With Area of Secondary Hyperalgesia? - Protocol for a 3-Tesla MRI Study of Healthy Volunteers. JMIR Res Protoc 2016; 5:e117. [PMID: 27317630 PMCID: PMC4930528 DOI: 10.2196/resprot.5680] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/08/2016] [Indexed: 11/13/2022] Open
Abstract
Background Experience and development of pain may be influenced by a number of physiological, psychological, and psychosocial factors. In a previous study we found differences in neuronal activation to noxious stimulation, and microstructural neuroanatomical differences, when comparing healthy volunteers with differences in size of the area of secondary hyperalgesia following a standardized burn injury. Objective We aim to investigate the degree of association between the volume of pain-relevant structures in the brain and the size of the area of secondary hyperalgesia following brief thermal sensitization. Methods The study consists of one experimental day, in which whole-brain magnetic resonance imaging (MRI) scans will be conducted including T1-weighed three-dimensional anatomy scan, diffusion tensor imaging, and resting state functional MRI. Before the experimental day, all included participants will undergo experimental pain testing in a parallel study (Clinicaltrials.gov Identifier: NCT02527395). Results from this experimental pain testing, as well as the size of the area of secondary hyperalgesia from the included participants, will be extracted from this parallel study. Results The association between the volume of pain-relevant structures in the brain and the area of secondary hyperalgesia will be investigated by linear regression of the estimated best linear unbiased predictors on the individual volumes of the pain relevant brain structures. Conclusions We plan to investigate the association between experimental pain testing parameters and the volume, connectivity, and resting state activity of pain-relevant structures in the brain. These results may improve our knowledge of the mechanisms responsible for the development of acute and chronic pain. ClinicalTrial Danish Research Ethics Committee (identifier: H-15010473). Danish Data Protection Agency (identifier: RH-2015-149). Clinicaltrials.gov NCT02567318; http://clinicaltrials.gov/ct2/show/NCT02567318 (Archived by WebCite at http://www.webcitation.org/6i4OtP0Oi)
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Affiliation(s)
- Morten Sejer Hansen
- Department of Anaesthesiology, 4231, Centre of head and orthopaedics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
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Hansen MS, Wetterslev J, Pipper CB, Asghar MS, Dahl JB. Is heat pain detection threshold associated with the area of secondary hyperalgesia following brief thermal sensitization? A study of healthy volunteers - design and detailed plan of analysis. BMC Anesthesiol 2016; 16:28. [PMID: 27246322 PMCID: PMC4888470 DOI: 10.1186/s12871-016-0193-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 05/15/2016] [Indexed: 12/12/2022] Open
Abstract
Background Several factors are believed to influence the development and experience of pain. Human clinical pain models are central tools, in the investigation of basic physiologic pain responses, and can be applied in patients as well as in healthy volunteers. Each clinical pain model investigates different aspects of the human pain response. Brief thermal sensitization induces a mild burn injury, resulting in development of primary hyperalgesia at the site of stimulation, and secondary hyperalgesia surrounding the site of stimulation. Central sensitization is believed to play an important role in the development of secondary hyperalgesia; however, a possible association of secondary hyperalgesia following brief thermal sensitization and other heat pain models remains unknown. Our aim with this study is to investigate how close the heat pain detection threshold is associated with the size of the area of secondary hyperalgesia induced by the clinical heat pain model: Brief thermal sensitization. Methods and design We aim to include 120 healthy participants. The participants will be tested on two separate study days with the following procedures: i) Brief thermal sensitization, ii) heat pain detection threshold and iii) pain during thermal stimulation. Additionally, the participants will be tested with the Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale questionnaires. We conducted statistical simulations based on data from our previous study, to estimate an empirical power of 99.9 % with α of 0.05. We define that an R2 < 0.25 and predictive intervals larger than +/−150 cm2 are indications of a weak association. Discussion The area of secondary hyperalgesia may serve as a quantitative measure of the central sensitization induced by cutaneous heat stimulation, and thus may be a biomarker of an individual’s pain sensitivity. The number of studies investigating secondary hyperalgesia is growing; however basic knowledge of the physiologic aspects of secondary hyperalgesia in humans is still incomplete. We therefore find it interesting to investigate if HPDT, a known quantitative sensory test, is associated with areas of secondary hyperalgesia following brief thermal sensitization Trial registration Clinicaltrials.gov (Identifier: NCT02527395). Danish Research Ethics Committee (Identifier: H-8-2014-012). Danish Data Protection Agency (Identifier: 30-1436). Electronic supplementary material The online version of this article (doi:10.1186/s12871-016-0193-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Morten Sejer Hansen
- Department of Anaesthesiology, 4231, Centre of Head and Orthopaedics, Rigshospitalet, Blegdamsvej 9, Copenhagen, 2100, Denmark.
| | - Jørn Wetterslev
- Copenhagen Trial Unit, Centre for Clinical Intervention Research, dep. 7812, Blegdamsvej 9, Copenhagen, 2100, Denmark
| | - Christian Bressen Pipper
- Section of Biostatistics, Faculty of Health, Copenhagen University, Øster Farigmagsgade 5, Copenhagen, 1014, Denmark
| | - Mohammad Sohail Asghar
- Department of Anaesthesiology, 4231, Centre of Head and Orthopaedics, Rigshospitalet, Blegdamsvej 9, Copenhagen, 2100, Denmark
| | - Jørgen Berg Dahl
- Department of Anaesthesiology, dep. Z, Bispebjerg Hospital, Bispebjerg Bakke 23, Copenhagen, 2400, Denmark
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Hansen MS, Wetterslev J, Pipper CB, Østervig R, Asghar MS, Dahl JB. The Area of Secondary Hyperalgesia following Heat Stimulation in Healthy Male Volunteers: Inter- and Intra-Individual Variance and Reproducibility. PLoS One 2016; 11:e0155284. [PMID: 27167119 PMCID: PMC4864410 DOI: 10.1371/journal.pone.0155284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 03/29/2016] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Clinical pain models can be applied when investigating basic physiologic pain responses in healthy volunteers. Several pain models exist; however, only few have been adequately validated. Our primary aim with this prospective study was to investigate the intra- and inter-individual variation in secondary hyperalgesia elicited by brief thermal sensitization (45°C for 3 min) in healthy volunteers. MATERIAL AND METHODS Fifty healthy volunteers were included. Areas of secondary hyperalgesia following brief thermal sensitization were investigated by 2 observers on 4 experimental days, with a minimum interval of 7 days. Additionally, heat pain detection threshold and pain during thermal stimulation (45°C for 1 min.), and the psychological tests Pain Catastrophizing Scale and Hospital Anxiety and Depression Score were applied. RESULTS For areas of secondary hyperalgesia, an intra-observer intra-person correlation of 0.85, 95% CI [0.78, 0.90], an intra-observer inter-person correlation of 0.03, 95% CI [0.00, 0.16], and a coefficient of variation of 0.17, 95% CI [0.14, 0.21] was demonstrated. Four percent of the study population had areas of secondary hyperalgesia both below the 1st and above the 3rd quartile considering all included participants. Heat pain detection threshold predicted area of secondary hyperalgesia with an adjusted R2 of 0.20 (P = 0.0006). CONCLUSIONS We have demonstrated a low intra-individual, and a high inter-individual variation in thermally induced secondary hyperalgesia. We conclude that brief thermal sensitization produce secondary hyperalgesia with a high level of reproducibility, which can be applied to investigate different phenotypes related to secondary hyperalgesia in healthy volunteers. TRIAL REGISTRATION clinicaltrials.gov NCT02166164.
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Affiliation(s)
- Morten Sejer Hansen
- Department of Anesthesiology 4231, Centre of Head and Orthopedics, Rigshospitalet, Copenhagen, Denmark
- * E-mail:
| | - Jørn Wetterslev
- Department 7812, Copenhagen Trial Unit, Centre for Clinical Intervention Research, Copenhagen, Denmark
| | | | - Rebecca Østervig
- Department of Anesthesiology 4231, Centre of Head and Orthopedics, Rigshospitalet, Copenhagen, Denmark
| | - Mohammad Sohail Asghar
- Department of Anesthesiology 4231, Centre of Head and Orthopedics, Rigshospitalet, Copenhagen, Denmark
| | - Jørgen Berg Dahl
- Department of Anesthesiology, Bispebjerg and Frederiksberg Hospitals, Copenhagen, Denmark
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Protein Kinase C γ Interneurons Mediate C-fiber–induced Orofacial Secondary Static Mechanical Allodynia, but Not C-fiber–induced Nociceptive Behavior. Anesthesiology 2016; 124:1136-52. [DOI: 10.1097/aln.0000000000001000] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abstract
Background
Tissue injury enhances pain sensitivity both at the site of tissue damage and in surrounding uninjured skin (secondary hyperalgesia). Secondary hyperalgesia encompasses several pain symptoms including pain to innocuous punctate stimuli or static mechanical allodynia. How injury-induced barrage from C-fiber nociceptors produces secondary static mechanical allodynia has not been elucidated.
Methods
Combining behavioral, immunohistochemical, and Western blot analysis, the authors investigated the cell and molecular mechanisms underlying the secondary static mechanical allodynia in the rat medullary dorsal horn (MDH) using the capsaicin model (n = 4 to 5 per group).
Results
Intradermal injection of capsaicin (25 μg) into the vibrissa pad produces a spontaneous pain and a secondary static mechanical allodynia. This allodynia is associated with the activation of a neuronal network encompassing lamina I–outer lamina III, including interneurons expressing the γ isoform of protein kinase C (PKCγ) within inner lamina II (IIi) of MDH. PKCγ is concomitantly phosphorylated (+351.4 ± 79.2%, mean ± SD; P = 0.0003). Mechanical allodynia and innocuous punctate stimulus–evoked laminae I to III neuronal activation can be replicated after intracisternally applied γ-aminobutyric acid receptor type A (GABAA) antagonist (bicuculline: 0.05 μg) or reactive oxygen species (ROS) donor (tert-butyl hydroperoxide: 50 to 250 ng). Conversely, intracisternal PKCγ antagonist, GABAA receptor agonist, or ROS scavenger prevent capsaicin-induced static mechanical allodynia and neuronal activation.
Conclusions
Sensitization of lamina IIi PKCγ interneurons is required for the manifestation of secondary static mechanical allodynia but not for spontaneous pain. Such sensitization is driven by ROS and GABAAergic disinhibition. ROS released during intense C-fiber nociceptor activation might produce a GABAAergic disinhibition of PKCγ interneurons. Innocuous punctate inputs carried by Aδ low-threshold mechanoreceptors onto PKCγ interneurons can then gain access to the pain transmission circuitry of superficial MDH, producing pain.
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You DS, Creech SK, Meagher MW. Enhanced Area of Secondary Hyperalgesia in Women with Multiple Stressful Life Events: A Pilot Study. PAIN MEDICINE 2016; 17:1859-1864. [DOI: 10.1093/pm/pnw049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ringsted TK, Enghuus C, Petersen MA, Werner MU. Demarcation of secondary hyperalgesia zones: Punctate stimulation pressure matters. J Neurosci Methods 2015; 256:74-81. [PMID: 26310180 DOI: 10.1016/j.jneumeth.2015.08.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 08/16/2015] [Accepted: 08/18/2015] [Indexed: 01/30/2023]
Abstract
BACKGROUND Secondary hyperalgesia is increased sensitivity in normal tissue near an injury, and it is a measure of central sensitization reflecting injury-related effects on the CNS. Secondary hyperalgesia areas (SHAs), usually assessed by polyamide monofilaments, are important outcomes in studies of analgesic drug effects in humans. However, since the methods applied in demarcating the secondary hyperalgesia zone seem inconsistent across studies, we examined the effect of a standardized approach upon the measurement of SHA following a first degree burn injury (BI). NEW METHOD The study was a two-observer, test-retest study with the two sessions separated by 6wk. An observer-blinded design adjusted to examine day-to-day and observer-to-observer variability in SHA was used. In 23 healthy volunteers (12 females/11 males) a BI was induced by a contact thermode (47.0°C, 420s, 2.5×5.0cm(2)). The SHA, demarcated by polyamide monofilaments (bending force: 0.2, 69 and 2569mN) and a "weighted-pin" stimulator (512mN), were assessed 45 to 75min after each BI. RESULTS A random effect, linear mixed model demonstrated a logarithmic correlation between elicited skin pressures (mN/mm(2)) and the SHAs (P<0.0001). No day-to-day or observer-to-observer differences in SHAs were observed. Intraclass correlation coefficients, in the range of 0.51 to 0.84, indicated a moderate to almost perfect reliability between observers. COMPARISON WITH EXISTING METHODS No standardized approach in SHA-assessment has hitherto been presented. CONCLUSIONS This is the first study to demonstrate that demarcation of secondary hyperalgesia zones depends on the developed pressure of the punctate stimulator used.
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Affiliation(s)
- Thomas K Ringsted
- Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Multidisciplinary Pain Center 7612, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark.
| | - Casper Enghuus
- Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Multidisciplinary Pain Center 7612, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Morten A Petersen
- Research Unit, Department of Palliative Care, Bispebjerg Hospital, Copenhagen University Hospitals, Copenhagen, Denmark
| | - Mads U Werner
- Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Multidisciplinary Pain Center 7612, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
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Correction: Secondary Hyperalgesia Phenotypes Exhibit Differences in Brain Activation during Noxious Stimulation. PLoS One 2015; 10:e0128640. [PMID: 25978430 PMCID: PMC4433100 DOI: 10.1371/journal.pone.0128640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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