1
|
Ingram S, Chisholm KI, Wang F, De Koninck Y, Denk F, Goodwin GL. Assessing spontaneous sensory neuron activity using in vivo calcium imaging. Pain 2024; 165:1131-1141. [PMID: 38112748 PMCID: PMC11017743 DOI: 10.1097/j.pain.0000000000003116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 09/01/2023] [Accepted: 09/23/2023] [Indexed: 12/21/2023]
Abstract
ABSTRACT Heightened spontaneous activity in sensory neurons is often reported in individuals living with chronic pain. It is possible to study this activity in rodents using electrophysiology, but these experiments require great skill and can be prone to bias. Here, we have examined whether in vivo calcium imaging with GCaMP6s can be used as an alternative approach. We show that spontaneously active calcium transients can be visualised in the fourth lumbar dorsal root ganglion (L4 DRG) through in vivo imaging in a mouse model of inflammatory pain. Application of lidocaine to the nerve, between the inflamed site and the DRG, silenced spontaneous firing and revealed the true baseline level of calcium for spontaneously active neurons. We used these data to train a machine learning algorithm to predict when a neuron is spontaneously active. We show that our algorithm is accurate in 2 different models of pain: intraplantar complete Freund adjuvant and antigen-induced arthritis, with accuracies of 90.0% ±1.2 and 85.9% ±2.1, respectively, assessed against visual inspection by an experienced observer. The algorithm can also detect neuronal activity in imaging experiments generated in a different laboratory using a different microscope configuration (accuracy = 94.0% ±2.2). We conclude that in vivo calcium imaging can be used to assess spontaneous activity in sensory neurons and provide a Google Colaboratory Notebook to allow anyone easy access to our novel analysis tool, for the assessment of spontaneous neuronal activity in their own imaging setups.
Collapse
Affiliation(s)
- Sonia Ingram
- Sonia Ingram, Data Scientist, Contract Researcher for King's College London, London, United Kingdom
| | - Kim I. Chisholm
- Pain Centre Versus Arthritis, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Feng Wang
- CERVO Brain Research Centre, Québec Mental Health Institute, Quebec City, QC, Canada
- Faculty of Dentistry, Laval University, Quebec, Canada
| | - Yves De Koninck
- CERVO Brain Research Centre, Québec Mental Health Institute, Quebec City, QC, Canada
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - George L. Goodwin
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| |
Collapse
|
2
|
Abstract
Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.
Collapse
Affiliation(s)
- Qihua Fan
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - A Gordon Smith
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| |
Collapse
|
3
|
Arora V, Li T, Kumari S, Wang S, Asgar J, Chung MK. Capsaicin-induced depolymerization of axonal microtubules mediates analgesia for trigeminal neuropathic pain. Pain 2022; 163:1479-1488. [PMID: 34724681 PMCID: PMC9046530 DOI: 10.1097/j.pain.0000000000002529] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/05/2021] [Accepted: 10/25/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Capsaicin is a specific agonist of transient receptor potential vanilloid 1 (TRPV1), which is enriched in nociceptors. Capsaicin not only produces acute pain but also leads to long-lasting analgesia in patients with chronic pain. Although capsaicin-induced TRPV1 and Ca 2+ /calpain-dependent ablation of axonal terminals is necessary for long-lasting analgesia, the mechanisms underlying capsaicin-induced ablation of axonal terminals and its association with analgesia are not fully understood. Microtubules are composed of tubulin polymers and serve as a main axonal cytoskeleton maintaining axonal integrity. In this study, we hypothesized that capsaicin would increase the depolymerization of microtubules and lead to axonal ablation and analgesia for trigeminal neuropathic pain. Paclitaxel, a microtubule stabilizer, decreased capsaicin-induced ablation of axonal terminals in time-lapsed imaging in vitro. Capsaicin increases free tubulin in dissociated sensory neurons, which was inhibited by paclitaxel. Consistently, subcutaneous injection of paclitaxel prevented capsaicin-induced axonal ablation in the hind paw skin. Capsaicin administration to the facial skin produced analgesia for mechanical hyperalgesia in mice with chronic constriction injury of the infraorbital nerve, which was prevented by the coadministration of paclitaxel and capsaicin. Whole-mount staining of facial skin showed that paclitaxel reduced capsaicin-induced ablation of peptidergic afferent terminals. Despite the suggested involvement of TRPV1 Ser801 phosphorylation on microtubule integrity, capsaicin-induced analgesia was not affected in TRPV1 S801A knock-in mice. In conclusion, capsaicin-induced depolymerization of axonal microtubules determined capsaicin-induced ablation of nociceptive terminals and the extent of analgesia. Further understanding of TRPV1/Ca 2+ -dependent mechanisms of capsaicin-induced ablation and analgesia may help to improve the management of chronic pain.
Collapse
Affiliation(s)
- Vipin Arora
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Tingting Li
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Sinu Kumari
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Sheng Wang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Jamila Asgar
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| |
Collapse
|
4
|
Roza C, Bernal L. Electrophysiological characterization of ectopic spontaneous discharge in axotomized and intact fibers upon nerve transection: a role in spontaneous pain? Pflugers Arch 2022; 474:387-396. [PMID: 35088129 DOI: 10.1007/s00424-021-02655-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022]
Abstract
Many patients experience positive symptoms after traumatic nerve injury. Despite the increasing number of experimental studies in models of peripheral neuropathy and the knowledge acquired, most of these patients lack an effective treatment for their chronic pain. One possible explanation might be that most of the preclinical studies focused on the development of mechanical or thermal allodynia/hyperalgesia, neglecting that most of the patients with peripheral neuropathies complain mostly about spontaneous forms of pains. Here, we summarize the aberrant electrophysiological behavior of peripheral nerve fibers recorded in experimental models, the underlying pathophysiological mechanisms, and their relationship with the symptoms reported by patients. Upon nerve section, axotomized but also intact fibers develop ectopic spontaneous activity. Most interestingly, a proportion of axotomized fibers might present receptive fields in the skin far beyond the site of damage, indicative of a functional cross talk between neuromatose and intact fibers. All these features can be linked with some of the symptoms that neuropathic patients experience. Furthermore, we spotlight the consequence of primary afferents with different patterns of spontaneous discharge on the neural code and its relationship with chronic pain states. With this article, readers will be able to understand the pathophysiological mechanisms that might underlie some of the symptoms that experience neuropathic patients, with a special focus on spontaneous pain.
Collapse
Affiliation(s)
- Carolina Roza
- Dpto. Biología de Sistemas, Edificio de Medicina Universidad de Alcalá, 28871, Alcalá de Henares, Madrid, Spain.
| | | |
Collapse
|
5
|
Fan Q, Gordon Smith A. Recent updates in the treatment of diabetic polyneuropathy. Fac Rev 2022. [PMID: 36311537 DOI: 10.1270/r/11-30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.
Collapse
Affiliation(s)
- Qihua Fan
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - A Gordon Smith
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| |
Collapse
|
6
|
Verdugo RJ, Matamala JM, Inui K, Kakigi R, Valls-Solé J, Hansson P, Bernhard Nilsen K, Lombardi R, Lauria G, Petropoulos IN, Malik RA, Treede RD, Baumgärtner U, Jara PA, Campero M. Review of techniques useful for the assessment of sensory small fiber neuropathies: Report from an IFCN expert group. Clin Neurophysiol 2022; 136:13-38. [DOI: 10.1016/j.clinph.2022.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/09/2023]
|
7
|
Powell JE, Boehm JO, Bicher JH, Reece CL, Davis SA, Pasquina PF. The Utility of Dynamic Movement Orthoses in the Management of Complex Regional Pain Syndrome-A Case Series. Mil Med 2021; 188:usab418. [PMID: 34626479 DOI: 10.1093/milmed/usab418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/17/2021] [Accepted: 09/27/2021] [Indexed: 11/14/2022] Open
Abstract
Complex regional pain syndrome (CRPS) is a relatively rare, but debilitating condition that may occur after limb or peripheral nerve trauma. Typical symptoms of CRPS include swelling, allodynia, hyperalgesia, and skin temperature changes. Although a variety of pharmacological and non-pharmacological approaches are commonly used in caring for individuals with CRPS, they are frequently ineffective and often associated with side effects and/or additional risks. Previously, elastomeric orthotic garments have been shown to decrease neuropathic pain, reduce edema, and increase proprioception, but no previous reports have described their use in treating CRPS. Accordingly, this case series describes our experiences using a Lycra-based, custom-fabricated Dynamic Movement Orthosis (DMO) as a novel treatment to reduce the symptoms of CRPS and promote function. Four patients were included in this case series, all of whom had very different causes for their CRPS, including a combat-related gunshot injury resulting in multiple foot fractures with a partial nerve injury, a post-metatarsophalangeal fusion, an L5 radiculopathy, and a case of post-lower leg fasciotomies. These four patients all reported subjective improvement in their pain, function, and exercise tolerance in association with their DMO use. All patients demonstrated reduced use of analgesic medications. The pre- and post-DMO lower extremity functional scale showed clinically significant improvement in the two patients for which it was obtained.
Collapse
Affiliation(s)
- Jordan E Powell
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Jamie O Boehm
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Jessica H Bicher
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Christopher L Reece
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Shelton A Davis
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Paul F Pasquina
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| |
Collapse
|
8
|
Raja SN, Ringkamp M, Guan Y, Campbell JN. John J. Bonica Award Lecture: Peripheral neuronal hyperexcitability: the "low-hanging" target for safe therapeutic strategies in neuropathic pain. Pain 2021; 161 Suppl 1:S14-S26. [PMID: 33090736 DOI: 10.1097/j.pain.0000000000001838] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | - Matthias Ringkamp
- Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Yun Guan
- Departments of Anesthesiology and Critical Care Medicine and.,Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - James N Campbell
- Neurological Surgery, Department of Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| |
Collapse
|
9
|
Farrell AT, Panepinto J, Carroll CP, Darbari DS, Desai AA, King AA, Adams RJ, Barber TD, Brandow AM, DeBaun MR, Donahue MJ, Gupta K, Hankins JS, Kameka M, Kirkham FJ, Luksenburg H, Miller S, Oneal PA, Rees DC, Setse R, Sheehan VA, Strouse J, Stucky CL, Werner EM, Wood JC, Zempsky WT. End points for sickle cell disease clinical trials: patient-reported outcomes, pain, and the brain. Blood Adv 2019; 3:3982-4001. [PMID: 31809538 PMCID: PMC6963237 DOI: 10.1182/bloodadvances.2019000882] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/26/2019] [Indexed: 12/12/2022] Open
Abstract
To address the global burden of sickle cell disease (SCD) and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to: patient-reported outcomes (PROs), pain (non-PROs), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the PROs, pain, and brain panels, as well as relevant findings and recommendations from the biomarkers panel. The panels identify end points, where there were supporting data, to use in clinical trials of SCD. In addition, the panels discuss where further research is needed to support the development and validation of additional clinical trial end points.
Collapse
Affiliation(s)
| | - Julie Panepinto
- Pediatric Hematology, Medical College of Wisconsin/Children's Wisconsin, Milwaukee, WI
| | - C Patrick Carroll
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD
| | | | - Ankit A Desai
- Krannert Institute of Cardiology, Indiana University, Bloomington, IN
| | - Allison A King
- Division of Hematology and Oncology in Pediatrics and Medicine, Washington University School of Medicine, St. Louis, MO
| | - Robert J Adams
- Department of Neurology, Medical University of South Carolina, Charleston, SC
| | | | - Amanda M Brandow
- Pediatric Hematology, Medical College of Wisconsin/Children's Wisconsin, Milwaukee, WI
| | - Michael R DeBaun
- Vanderbilt-Meharry Center of Excellence in Sickle Cell Disease, Vanderbilt University Medical Center, Nashville, TN
| | - Manus J Donahue
- Department of Radiology and Radiological Sciences
- Department of Neurology, and
- Department of Psychiatry, School of Medicine, Vanderbilt University, Nashville, TN
| | - Kalpna Gupta
- Division of Hematology, Oncology, and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN
| | - Jane S Hankins
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN
| | - Michelle Kameka
- Nicole Wertheim College of Nursing and Health Sciences, Florida International University, Miami, FL
| | - Fenella J Kirkham
- Developmental Neurosciences Unit and
- Biomedical Research Unit, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Harvey Luksenburg
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | | | | | - David C Rees
- Department of Haematological Medicine, King's College Hospital, London, United Kingdom
- School of Cancer and Pharmaceutical Sciences, King's College London, London, United Kingdom
| | | | - Vivien A Sheehan
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - John Strouse
- Division of Hematology, Department of Medicine, and
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Cheryl L Stucky
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI
| | - Ellen M Werner
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - John C Wood
- Children's Hospital Los Angeles, Los Angeles, CA; and
| | - William T Zempsky
- Department of Pediatrics, Connecticut Children's/School of Medicine, University of Connecticut, Hartford, CT
| |
Collapse
|
10
|
Quintal I, Poiré-Hamel L, Bourbonnais D, Dyer JO. Management of long-term complex regional pain syndrome with allodynia: A case report. J Hand Ther 2019; 31:255-264. [PMID: 29706199 DOI: 10.1016/j.jht.2018.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 01/16/2018] [Accepted: 01/22/2018] [Indexed: 02/03/2023]
Abstract
STUDY DESIGN Case report. INTRODUCTION Conventional rehabilitation alone may not be effective in reducing symptoms in some patients with complex regional pain syndrome. PURPOSE OF THE STUDY This case report portrays the benefits of a new tailored rehabilitation program for a 39-year-old patient suffering from upper limb complex regional pain syndrome with severe touch-evoked pain (static mechanical allodynia). METHODS This patient had previously received conventional rehabilitation for a year and a half including physical and nonsurgical medical interventions that did not improve symptoms or function. In the search for an alternative, this patient was referred to occupational therapy to try a tailored rehabilitation program, drawing on multiple strategies used sequentially according to the patient's tolerance and symptom evolution. During this 22-month program, the following methods were added (listed chronologically): somatosensory rehabilitation of pain method, graded motor imagery, pain management modalities, active mobilizations, strengthening exercises, and task simulation. The patient successively showed resolution of mechanical allodynia, decreased pain, reduction of tactile hypesthesia and improvement in active range of motion, strength, and function. These improvements allowed him to return to work. DISCUSSION This suggests that a tailored rehabilitation program combining somatosensory rehabilitation of pain method, graded motor imagery and more conventional approaches could improve symptoms and functional status in patients with upper limb complex regional pain syndrome, even with persistent refractory symptoms. CONCLUSION The addition of the somatosensory rehabilitation of pain method and the graded motor imagery approach to conventional therapy could be considered in cases of complex regional pain syndrome that do not respond to conventional rehabilitation alone.
Collapse
Affiliation(s)
- Isabelle Quintal
- School of Rehabilitation, Université de Montréal, Quebec, Canada; Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal, Quebec, Canada; Centre Professionnel d'Ergothérapie, Montreal, Quebec, Canada
| | | | - Daniel Bourbonnais
- School of Rehabilitation, Université de Montréal, Quebec, Canada; Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal, Quebec, Canada
| | - Joseph-Omer Dyer
- School of Rehabilitation, Université de Montréal, Quebec, Canada.
| |
Collapse
|
11
|
Complex regional pain syndrome: a focus on the autonomic nervous system. Clin Auton Res 2019; 29:457-467. [PMID: 31104164 DOI: 10.1007/s10286-019-00612-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/07/2019] [Indexed: 12/15/2022]
Abstract
PURPOSE Although autonomic features are part of the diagnostic criteria for complex regional pain syndrome (CRPS), the role of the autonomic nervous system in CRPS pathophysiology has been downplayed in recent years. The purpose of this review is to redress this imbalance. METHODS We focus in this review on the contribution of the autonomic nervous system to CRPS pathophysiology. In particular, we discuss regional sympathetic and systemic autonomic disturbances in CRPS and the mechanisms which may underlie them, and consider links between these mechanisms, immune disturbances and pain. RESULTS The focused literature research revealed that immune reactions, alterations in receptor populations (e.g., upregulation of adrenoceptors and reduced cutaneous nerve fiber density) and central changes in autonomic drive seem to contribute to regional and systemic disturbances in sympathetic activity and to sympathetically maintained pain in CRPS. CONCLUSIONS We conclude that alterations in the sympathetic nervous system contribute to CRPS pathology. Understanding these alterations may be an important step towards providing appropriate treatments for CRPS.
Collapse
|
12
|
Stanton-Hicks MD. CRPS: what’s in a name? Taxonomy, epidemiology, neurologic, immune and autoimmune considerations. Reg Anesth Pain Med 2019; 44:376-387. [DOI: 10.1136/rapm-2018-100064] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 09/25/2018] [Accepted: 10/03/2018] [Indexed: 12/26/2022]
Abstract
This account of the condition now termed complex regional pain syndrome (CRPS) spans approximately 462 years since a description embodying similar clinical features was described by Ambroise Paré in 1557. While reviewing its historical origins, the text describes why it became necessary to change the taxonomies of two clinical syndromes with similar pathophysiologies to one which acknowledges this aspect but does not introduce any mechanistic overtones. Discussed at length is the role of the sympathetic component of the autonomic nervous system (ANS) and why its dysfunction has both directly and indirectly influenced our understanding of the inflammatory aspects of CRPS. As the following article will show, our knowledge has expanded in an exponential fashion to include musculoskeletal, immune, autoimmune, central and peripheral nervous system and ANS dysfunction, all of which increase the complexity of its clinical management. A burgeoning literature is beginning to shed light on the mechanistic aspects of these syndromes and the increasing evidence of a genetic influence on such factors as autoimmunity, and its importance is also discussed at length. An important aspect that has been missing from the diagnostic criteria is a measure of disease severity. The recent validation of a CRPS Severity Score is also included.
Collapse
|
13
|
Ackerley R, Watkins RH. Microneurography as a tool to study the function of individual C-fiber afferents in humans: responses from nociceptors, thermoreceptors, and mechanoreceptors. J Neurophysiol 2018; 120:2834-2846. [PMID: 30256737 DOI: 10.1152/jn.00109.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The technique of microneurography-recording neural traffic from nerves in awake humans-has provided us with unrivaled insights into afferent and efferent processes in the peripheral nervous system for over 50 years. We review the use of microneurography to study single C-fiber afferents and provide an overview of the knowledge gained, with views to future investigations. C-fibers have slowly conducting, thin-diameter, unmyelinated axons and make up the majority of the fibers in peripheral nerves (~80%). With the use of microneurography in humans, C-fiber afferents have been differentiated into discrete subclasses that encode specific qualities of stimuli on the skin, and their functional roles have been investigated. Afferent somatosensory information provided by C-fibers underpins various positive and negative affective sensations from the periphery, including mechanical, thermal, and chemical pain (C-nociceptors), temperature (C-thermoreceptors), and positive affective aspects of touch (C-tactile afferents). Insights from microneurographic investigations have revealed the complexity of the C-fiber system, methods for delineating fundamental C-fiber populations in a translational manner, how C-fiber firing can be used to identify nerve deficits in pathological states, and how the responses from C-fibers may be modified to change sensory percepts, including decreasing pain. Understanding these processes may lead to future medical interventions to diagnose and treat C-fiber dysfunction. NEW & NOTEWORTHY The technique of microneurography allows us to directly investigate the functional roles of single C-fiber afferents in awake human beings. Here we outline and discuss the current field of C-fiber research on this heterogeneous population of afferents in healthy subjects, in pathological states, and from a translational perspective. We cover C-fibers encoding touch, temperature, and pain and provide perspectives on the future of C-fiber microneurography investigations in humans.
Collapse
Affiliation(s)
- Rochelle Ackerley
- Aix Marseille University, CNRS, LNSC (Laboratoire de Neurosciences Sensorielles et Cognitives - UMR 7260), Marseille, France.,Department of Physiology, University of Gothenburg , Gothenburg , Sweden
| | | |
Collapse
|
14
|
Méndez-Rebolledo G, Gatica-Rojas V, Torres-Cueco R, Albornoz-Verdugo M, Guzmán-Muñoz E. Update on the effects of graded motor imagery and mirror therapy on complex regional pain syndrome type 1: A systematic review. J Back Musculoskelet Rehabil 2017; 30:441-449. [PMID: 27858687 DOI: 10.3233/bmr-150500] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Graded motor imagery (GMI) and mirror therapy (MT) is thought to improve pain in patients with complex regional pain syndrome (CRPS) types 1 and 2. However, the evidence is limited and analysis are not independent between types of CRPS. The purpose of this review was to analyze the effects of GMI and MT on pain in independent groups of patients with CRPS types 1 and 2. Searches for literature published between 1990 and 2016 were conducted in databases. Randomized controlled trials that compared GMI or MT with other treatments for CRPS types 1 and 2 were included. Six articles met the inclusion criteria and were classified from moderate to high quality. The total sample was composed of 171 participants with CRPS type 1. Three studies presented GMI with 3 components and three studies only used the MT. The studies were heterogeneous in terms of sample size and the disorders that triggered CRPS type 1. There were no trials that included participants with CRPS type 2. GMI and MT can improve pain in patients with CRPS type 1; however, there is not sufficient evidence to recommend these therapies over other treatments given the small size and heterogeneity of the studied population.
Collapse
Affiliation(s)
- Guillermo Méndez-Rebolledo
- Human Motor Control Laboratory, Department of Human Movement Sciences, Faculty of Health Sciences, Universidad de Talca, Talca, Chile.,Escuela de Kinesiología, Facultad de Salud, Universidad Santo Tomás, Chile
| | - Valeska Gatica-Rojas
- Human Motor Control Laboratory, Department of Human Movement Sciences, Faculty of Health Sciences, Universidad de Talca, Talca, Chile
| | | | - María Albornoz-Verdugo
- Department of Basic Biomedical Sciences, Faculty of Health Sciences, Universidad de Talca, Talca, Chile
| | | |
Collapse
|
15
|
Walters ET. How is chronic pain related to sympathetic dysfunction and autonomic dysreflexia following spinal cord injury? Auton Neurosci 2017; 209:79-89. [PMID: 28161248 DOI: 10.1016/j.autneu.2017.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 12/29/2022]
Abstract
Autonomic dysreflexia (AD) and neuropathic pain occur after severe injury to higher levels of the spinal cord. Mechanisms underlying these problems have rarely been integrated in proposed models of spinal cord injury (SCI). Several parallels suggest significant overlap of these mechanisms, although the relationships between sympathetic function (dysregulated in AD) and nociceptive function (dysregulated in neuropathic pain) are complex. One general mechanism likely to be shared is central sensitization - enhanced responsiveness and synaptic reorganization of spinal circuits that mediate sympathetic reflexes or that process and relay pain-related information to the brain. Another is enhanced sensory input to spinal circuits caused by extensive alterations in primary sensory neurons. Both AD and SCI-induced neuropathic pain are associated with spinal sprouting of peptidergic nociceptors that might increase synaptic input to the circuits involved in AD and SCI pain. In addition, numerous nociceptors become hyperexcitable, hypersensitive to chemicals associated with injury and inflammation, and spontaneously active, greatly amplifying sensory input to sensitized spinal circuits. As discussed with the aid of a preliminary functional model, these effects are likely to have mutually reinforcing relationships with each other, and with consequences of SCI-induced interruption of descending excitatory and inhibitory influences on spinal circuits, with SCI-induced inflammation in the spinal cord and in DRGs, and with activity in sympathetic fibers within DRGs that promotes local inflammation and spontaneous activity in sensory neurons. This model suggests that interventions selectively targeting hyperactivity in C-nociceptors might be useful for treating chronic pain and AD after high SCI.
Collapse
Affiliation(s)
- Edgar T Walters
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA.
| |
Collapse
|
16
|
Effects of a T-type calcium channel blocker, ABT-639, on spontaneous activity in C-nociceptors in patients with painful diabetic neuropathy: a randomized controlled trial. Pain 2016; 156:2175-2183. [PMID: 26035253 DOI: 10.1097/j.pain.0000000000000249] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
T-type calcium channels are a potential novel target for treatment of neuropathic pain such as painful diabetic neuropathy. ABT-639 is a peripherally acting highly selective T-type Ca(v)3.2 calcium channel blocker that has demonstrated analgesic efficacy in preclinical models and may have the potential to reduce spontaneous fiber activity. Microneurography is a unique technique that directly assesses the function of peripheral sensory afferents and measures abnormal spontaneous activity in single peripheral nociceptive C fibers. Abnormal spontaneous activity in C-nociceptors functions as a marker for spontaneous pain, as reduction of this activity could indicate analgesic efficacy. This randomized, double-blind controlled study evaluated the effects of a single 100-mg oral dose of ABT-639, compared with placebo, on abnormal spontaneous activity in peripheral C-nociceptors, measured for the first time by microneurography in adult patients with painful diabetic neuropathy. Lidocaine was included in this study and compared with placebo. Pharmacokinetics and safety of ABT-639 were evaluated. Thirty-nine patients were randomized, and a total of 56 analyzable C-nociceptors with spontaneous activity were identified in 34 patients. There were no significant differences in C-nociceptor activities after ABT-639 treatment vs placebo. Similar findings were observed for lidocaine vs placebo. There were no clinically significant findings in the safety of ABT-639. Further research of T-type Ca(v)3.2 calcium channels as potential treatment targets for painful diabetic neuropathy is warranted. The utilization of microneurography as a means to measure abnormal activity in C-nociceptors in human clinical studies opens new possibilities for future studies of compounds targeting peripheral nerve hyperexcitability. ClinicalTrials.gov identifier: NCT01589432.
Collapse
|
17
|
Abstract
Despite the severe pain and disability associated with complex regional pain syndrome (CRPS), the lack of understanding of the pathophysiological mechanisms supporting this enigmatic condition prevents the rational design of new therapies, a situation that is frustrating to both the physician and the patient. The review highlights some of the mechanisms thought to be involved in the pathophysiology of CRPS in preclinical models and CRPS patients, with the ultimate goal that understanding these mechanisms will lead to the design of efficacious, mechanism-based treatments available to the clinic.
Collapse
Affiliation(s)
- Maral Tajerian
- Veterans Affairs Palo Alto Health Care System Palo Alto, CA, USA,Department of Anesthesiology, Stanford University School of Medicine, Stanford, CA, USA
| | - J David Clark
- Veterans Affairs Palo Alto Health Care System Palo Alto, CA, USA,Department of Anesthesiology, Stanford University School of Medicine, Stanford, CA, USA,Corresponding author: J David Clark, MD, PhD., Anesthesia Service, Veterans Affairs Palo Alto Health Care, System, 3801 Miranda Ave., Palo Alto, CA 94304, USA, Tel: 650-493-5000 ext. 60479, Fax: 650-852-3423,
| |
Collapse
|
18
|
Microneurographic recording from unmyelinated nerve fibers in neurological disorders: An update. Clin Neurophysiol 2015; 126:437-45. [DOI: 10.1016/j.clinph.2014.10.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/25/2014] [Accepted: 10/06/2014] [Indexed: 12/14/2022]
|
19
|
Abstract
Complex regional pain syndrome (CRPS) is the current consensus-derived name for a syndrome usually triggered by limb trauma. Required elements include prolonged, disproportionate distal-limb pain and microvascular dysregulation (e.g., edema or color changes) or altered sweating. CRPS-II (formerly "causalgia") describes patients with identified nerve injuries. CRPS-I (formerly "reflex sympathetic dystrophy") describes most patients who lack evidence of specific nerve injuries. Diagnosis is clinical and the pathophysiology involves combinations of small-fiber axonopathy, microvasculopathy, inflammation, and brain plasticity/sensitization. Females have much higher risk and workplace accidents are a well-recognized cause. Inflammation and dysimmunity, perhaps facilitated by injury to the blood-nerve barrier, may contribute. Most patients, particularly the young, recover gradually, but treatment can speed healing. Evidence of efficacy is strongest for rehabilitation therapies (e.g., graded-motor imagery), neuropathic pain medications, and electric stimulation of the spinal cord, injured nerve, or motor cortex. Investigational treatments include ketamine, botulinum toxin, immunoglobulins, and transcranial neuromodulation. Nonrecovering patients should be re-evaluated for neurosurgically treatable causal lesions (nerve entrapment, impingement, infections, or tumors) and treatable potentiating medical conditions, including polyneuropathy and circulatory insufficiency. Earlier impressions that CRPS represents malingering or psychosomatic illness have been replaced by evidence that CRPS is a rare complication of limb injury in biologically susceptible individuals.
Collapse
Affiliation(s)
- Anne Louise Oaklander
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA; Department of Pathology (Neuropathology), Massachusetts General Hospital, Boston, MA, USA.
| | - Steven H Horowitz
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA; Department of Neurology, School of Medicine, Tufts University, Boston, MA, USA
| |
Collapse
|
20
|
Finch PM, Drummond ES, Dawson LF, Phillips JK, Drummond PD. Up-regulation of cutaneous α1 -adrenoceptors in complex regional pain syndrome type I. PAIN MEDICINE 2014; 15:1945-56. [PMID: 25220453 DOI: 10.1111/pme.12548] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND In a small radioligand-binding study of cutaneous α1 -adrenoceptors in complex regional pain syndrome (CRPS), signal intensity was greater in the CRPS-affected limb than in controls. However, it was not possible to localize heightened expression of α1 -adrenoceptors to nerves, sweat glands, blood vessels, or keratinocytes using this technique. METHODS To explore this in the present study, skin biopsies were obtained from 31 patients with CRPS type I and 23 healthy controls of similar age and sex distribution. Expression of α1 -adrenoceptors on keratinocytes and on dermal blood vessels, sweat glands, and nerves was assessed using immunohistochemistry. RESULTS α1 -Adrenoceptors were expressed more strongly in dermal nerve bundles and the epidermis both on the affected and contralateral unaffected side in patients than in controls (P<0.05). However, expression of α1 -adrenoceptors in sweat glands and blood vessels was similar in patients and controls. α1 -Adrenoceptor staining intensity in the CRPS-affected epidermis was associated with pain intensity (P < 0.05), but a similar trend for nerve bundles did not achieve statistical significance. DISCUSSION Epidermal cells influence nociception by releasing ligands that act on sensory nerve fibers. Moreover, an increased expression of α1 -adrenoceptors on nociceptive afferents has been shown to aggravate neuropathic pain. Thus, the heightened expression of α1 -adrenoceptors in dermal nerves and epidermal cells might augment pain and neuroinflammatory disturbances after tissue injury in patients with CRPS type I.
Collapse
Affiliation(s)
- Philip M Finch
- Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia
| | | | | | | | | |
Collapse
|
21
|
Gierthmühlen J, Binder A, Baron R. Mechanism-based treatment in complex regional pain syndromes. Nat Rev Neurol 2014; 10:518-28. [DOI: 10.1038/nrneurol.2014.140] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
22
|
Wang F, Stefano GB, Kream RM. Epigenetic modification of DRG neuronal gene expression subsequent to nerve injury: etiological contribution to complex regional pain syndromes (Part I). Med Sci Monit 2014; 20:1067-77. [PMID: 24961509 PMCID: PMC4081136 DOI: 10.12659/msm.890702] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
DRG is of importance in relaying painful stimulation to the higher pain centers and therefore could be a crucial target for early intervention aimed at suppressing primary afferent stimulation. Complex regional pain syndrome (CRPS) is a common pain condition with an unknown etiology. Recently added new information enriches our understanding of CRPS pathophysiology. Researches on genetics, biogenic amines, neurotransmitters, and mechanisms of pain modulation, central sensitization, and autonomic functions in CRPS revealed various abnormalities indicating that multiple factors and mechanisms are involved in the pathogenesis of CRPS. Epigenetics refers to mitotically and meiotically heritable changes in gene expression that do not affect the DNA sequence. As epigenetic modifications potentially play an important role in inflammatory cytokine metabolism, neurotransmitter responsiveness, and analgesic sensitivity, they are likely key factors in the development of chronic pain. In this dyad review series, we systematically examine the nerve injury-related changes in the neurological system and their contribution to CRPS. In this part, we first reviewed and summarized the role of neural sensitization in DRG neurons in performing function in the context of pain processing. Particular emphasis is placed on the cellular and molecular changes after nerve injury as well as different models of inflammatory and neuropathic pain. These were considered as the potential molecular bases that underlie nerve injury-associated pathogenesis of CRPS.
Collapse
Affiliation(s)
- Fuzhou Wang
- Department of Anesthesiology and Critical Care Medicine, Affiliated Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing, China (mainland)
| | - George B Stefano
- Neuroscience Research Institute, State University of New York at Old Westbury, Old Westbury, USA
| | - Richard M Kream
- Neuroscience Research Institute, State University of New York at Old Westbury, Old Westbury, USA
| |
Collapse
|
23
|
Drummond PD, Drummond ES, Dawson LF, Mitchell V, Finch PM, Vaughan CW, Phillips JK. Upregulation of α1-adrenoceptors on cutaneous nerve fibres after partial sciatic nerve ligation and in complex regional pain syndrome type II. Pain 2014; 155:606-616. [DOI: 10.1016/j.pain.2013.12.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/07/2013] [Accepted: 12/10/2013] [Indexed: 10/25/2022]
|
24
|
Borchers A, Gershwin M. Complex regional pain syndrome: A comprehensive and critical review. Autoimmun Rev 2014; 13:242-65. [DOI: 10.1016/j.autrev.2013.10.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2013] [Indexed: 12/19/2022]
|
25
|
Schlereth T, Drummond PD, Birklein F. Inflammation in CRPS: role of the sympathetic supply. Auton Neurosci 2013; 182:102-7. [PMID: 24411269 DOI: 10.1016/j.autneu.2013.12.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/11/2013] [Indexed: 12/21/2022]
Abstract
Acute Complex Regional Pain Syndrome (CRPS) is associated with signs of inflammation such as increased skin temperature, oedema, skin colour changes and pain. Pro-inflammatory cytokines (tumour necrosis factor-α (TNF-α), interleukin-2 (IL-2), IL-1beta, IL-6) are up-regulated, whereas anti-inflammatory cytokines (IL-4, IL-10) are diminished. Adaptive immunity seems to be involved in CRPS pathophysiology as many patients have autoantibodies directed against β2 adrenergic and muscarinic-2 receptors. In an animal tibial fracture model changes in the innate immune response such as up-regulation of keratinocytes are also found. Additionally, CRPS is accompanied by increased neurogenic inflammation which depends mainly on neuropeptides such as CGRP and Substance P. Besides inflammatory signs, sympathetic nervous system involvement in CRPS results in cool skin, increased sweating and sympathetically-maintained pain. The norepinephrine level is lower in the CRPS-affected than contralateral limb, but sympathetic sprouting and up-regulation of alpha-adrenoceptors may result in an adrenergic supersensitivity. The sympathetic nervous system and inflammation interact: norepinephrine influences the immune system and the production of cytokines. There is substantial evidence that this interaction contributes to the pathophysiology and clinical presentation of CRPS, but this interaction is not straightforward. How inflammation in CRPS might be exaggerated by sympathetic transmitters requires further elucidation.
Collapse
Affiliation(s)
- Tanja Schlereth
- Department of Neurology, Langenbeckstr, 1, D-55131 Mainz, Germany.
| | - Peter D Drummond
- School of Psychology and Exercise Science, Murdoch University, 6150 Western Australia, Australia
| | - Frank Birklein
- Department of Neurology, Langenbeckstr, 1, D-55131 Mainz, Germany
| |
Collapse
|
26
|
|
27
|
Kleggetveit IP, Namer B, Schmidt R, Helås T, Rückel M, Ørstavik K, Schmelz M, Jørum E. High spontaneous activity of C-nociceptors in painful polyneuropathy. Pain 2012; 153:2040-2047. [DOI: 10.1016/j.pain.2012.05.017] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 05/07/2012] [Accepted: 05/15/2012] [Indexed: 02/07/2023]
|
28
|
Bennett GJ. What Is Spontaneous Pain and Who Has It? THE JOURNAL OF PAIN 2012; 13:921-9. [DOI: 10.1016/j.jpain.2012.05.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 01/05/2023]
|
29
|
Double spikes to single electrical stimulation correlates to spontaneous activity of nociceptors in painful neuropathy patients. Pain 2012; 153:391-398. [DOI: 10.1016/j.pain.2011.10.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 09/29/2011] [Accepted: 10/28/2011] [Indexed: 11/21/2022]
|
30
|
Microneurographic identification of spontaneous activity in C-nociceptors in neuropathic pain states in humans and rats. Pain 2011; 153:42-55. [PMID: 21993185 DOI: 10.1016/j.pain.2011.08.015] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 07/11/2011] [Accepted: 08/15/2011] [Indexed: 12/21/2022]
Abstract
C-nociceptors do not normally fire action potentials unless challenged by adequate noxious stimuli. However, in pathological states nociceptors may become hyperexcitable and may generate spontaneous ectopic discharges. The aim of this study was to compare rat neuropathic pain models and to assess their suitability to model the spontaneous C-nociceptor activity found in neuropathic pain patients. Studies were performed in normal rats (n=40), healthy human subjects (n=15), peripheral neuropathic pain patients (n=20), and in five rat neuropathic pain models: nerve crush (n=24), suture (n=14), chronic constriction injury (n=12), STZ-induced diabetic neuropathy (n=56), and ddC-induced neuropathy (n=15). Microneurographic recordings were combined with electrical stimulation to monitor activity in multiple C fibers. Stimulation at 0.25 Hz allowed spontaneous impulses to be identified by fluctuations in baseline latency. Abnormal latency fluctuations could be produced by several mechanisms, and spontaneous activity was most reliably identified by the presence of unexplained latency increases corresponding to two or more additional action potentials. Spontaneous activity was present in a proportion of mechano-insensitive C-nociceptors in the patients and all rat models. The three focal traumatic nerve injury models provided the highest proportion (59.5%), whereas the two polyneuropathy models had fewer (18.6%), and the patients had an intermediate proportion (33.3%). Spontaneously active mechano-sensitive C-nociceptors were not recorded. Microneurographic recordings of spontaneous activity in diseased C-nociceptors may be useful for both short- and long-term drug studies, both in animals and in humans.
Collapse
|
31
|
van Eijs F, Huygen F, Van Zundert J. In Response: Intravenous Regional Guanethidine for Complex Regional Pain Syndrome. Pain Pract 2011. [DOI: 10.1111/j.1533-2500.2011.00483.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
32
|
Napeñas JJ, Zakrzewska JM. Diagnosis and management of trigeminal neuropathic pains. Pain Manag 2011; 1:353-65. [DOI: 10.2217/pmt.11.35] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
SUMMARY Trigeminal neuropathic pains have presented diagnostic and therapeutic challenges to providers. In addition, knowledge of pathophysiology, current classification systems, taxonomy and phenotyping of these conditions are incomplete. While trigeminal neuralgia is the most identifiable and studied, other conditions are being recognized and require distinct management approaches. Furthermore, other facial pain conditions such as atypical odontalgia and burning mouth syndrome are now considered to have neuropathic elements in their etiology. This article reviews current knowledge on the pathophysiology, diagnosis and management of neuropathic pain conditions involving the trigeminal nerve, to include: trigeminal neuralgia, trigeminal neuropathic pain (with traumatically induced neuralgia and atypical odontalgia) and burning mouth syndrome. Treatment modalities are reviewed based on current and best available evidence. Trigeminal neuralgia is managed with anticonvulsant drugs as the first line, with surgical options providing variable results. Trigeminal neuropathic pain is managed medically based on the guidelines for other neuropathic pain conditions. Burning mouth syndrome is also treated with a number of neuropathic medications, both topical and systemic. In all these conditions, patients need to be thoroughly educated about their condition, involved in its management, and be provided with supportive and adjunctive treatment resources.
Collapse
Affiliation(s)
- Joel J Napeñas
- Department of Oral Medicine, Carolinas Medical Center, Charlotte, NC, USA
| | - Joanna M Zakrzewska
- Division of Diagnostic, Surgical and Medical Sciences, Eastman Dental Hospital, London, UK
| |
Collapse
|
33
|
Campero M, Bostock H, Baumann TK, Ochoa JL. Activity-dependent slowing properties of an unmyelinated low threshold mechanoreceptor in human hairy skin. Neurosci Lett 2011; 493:92-6. [PMID: 21335061 DOI: 10.1016/j.neulet.2011.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 02/01/2011] [Accepted: 02/05/2011] [Indexed: 02/04/2023]
Abstract
It has been previously shown that unmyelinated afferent fibres in human skin are differentiated not only by their receptor characteristics, but also by their profiles of activity-dependent slowing. One type of profile, described originally as 'type 3', is different from that of nociceptors (type 1), cold afferents (type 2) and sympathetic efferents (type 4), in that these fibres display a minimal activity-dependent slowing (∼1% at 2 Hz). However, their function remains to be determined. Here we describe one unit with a typical 'type 3' activity-dependent slowing profile recorded from an undamaged fascicle of the superficial peroneal nerve of a patient. Its conduction velocity was 1.8 m s(-1) and it slowed by 1.3% during the 2 Hz tetanus. This unit had a mechanical receptive field in the hairy skin and responded readily to weak mechanical stimuli, and not to cold. This suggests that the low threshold unmyelinated mechanoreceptors recently described in human hairy skin are probably endowed with a 'type 3' activity-dependent profile.
Collapse
Affiliation(s)
- Mario Campero
- Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Chile.
| | | | | | | |
Collapse
|
34
|
Dawson LF, Phillips JK, Finch PM, Inglis JJ, Drummond PD. Expression of α1-adrenoceptors on peripheral nociceptive neurons. Neuroscience 2010; 175:300-14. [PMID: 21182905 DOI: 10.1016/j.neuroscience.2010.11.064] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 11/26/2010] [Accepted: 11/30/2010] [Indexed: 01/06/2023]
Abstract
The purpose of this study was to determine whether α(1)-adrenoceptors are expressed on primary nociceptive afferents that innervate healthy skin. Skin and dorsal root ganglia were collected from adult male Wistar rats and assessed using fluorescence immunohistochemistry with antibodies directed against α(1)-adrenoceptors alone or in combination with specific labels including myelin basic protein and neurofilament 200 (markers of myelinated nerve fibres), protein gene product 9.5 (a pan-neuronal marker), tyrosine hydroxylase (sympathetic neurons), isolectin B(4) (IB(4): non-peptidergic sensory neurons), calcitonin gene related peptide (CGRP) and transient receptor potential vanilloid receptor 1 (TRPV1) (peptidergic sensory neurons). Double labelling in dorsal root ganglia confirmed the expression of α(1)-adrenoceptors within sub-populations of CGRP, IB(4) and TRPV1 immunoreactive neurons. Myelinated and unmyelinated sensory nerve fibres in the skin expressed α(1)-adrenoceptors whereas sympathetic nerve fibres did not. The expression of α(1)-adrenoceptors on C- and A-delta nociceptive afferent fibres provides a histochemical substrate for direct excitation of these fibres by adrenergic agonists. This may help to explain the mechanism of sensory-sympathetic coupling that sometimes develops on surviving primary nociceptive afferents in neuropathic pain states.
Collapse
Affiliation(s)
- L F Dawson
- Faculty of Health Sciences, Murdoch University, Perth, Western Australia
| | | | | | | | | |
Collapse
|
35
|
Macefield VG. A role for the sympathetic nervous system in sympathetically maintained pain? Clin Neurophysiol 2010; 121:996-7. [PMID: 20231112 DOI: 10.1016/j.clinph.2010.02.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 02/12/2010] [Indexed: 12/26/2022]
|