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Choi D, Goodwin G, Stevens EB, Soliman N, Namer B, Denk F. Spontaneous activity in peripheral sensory nerves: a systematic review. Pain 2024; 165:983-996. [PMID: 37991272 PMCID: PMC11017746 DOI: 10.1097/j.pain.0000000000003115] [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: 06/20/2023] [Revised: 08/29/2023] [Accepted: 09/23/2023] [Indexed: 11/23/2023]
Abstract
ABSTRACT In the peripheral nervous system, spontaneous activity in sensory neurons is considered to be one of the 2 main drivers of chronic pain states, alongside neuronal sensitization. Despite this, the precise nature and timing of this spontaneous activity in neuropathic pain is not well-established. Here, we have performed a systematic search and data extraction of existing electrophysiological literature to shed light on which fibre types have been shown to maintain spontaneous activity and over what time frame. We examined both in vivo recordings of preclinical models of neuropathic pain, as well as microneurography recordings in humans. Our analyses reveal that there is broad agreement on the presence of spontaneous activity in neuropathic pain conditions, even months after injury or years after onset of neuropathic symptoms in humans. However, because of the highly specialised nature of the electrophysiological methods used to measure spontaneous activity, there is also a high degree of variability and uncertainty around these results. Specifically, there are very few directly controlled experiments, with less directly comparable data between human and animals. Given that spontaneous peripheral neuron activity is considered to be a key mechanistic feature of chronic pain conditions, it may be beneficial to conduct further experiments in this space.
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Affiliation(s)
- Dongchan Choi
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - George Goodwin
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - Edward B. Stevens
- Metrion Biosciences Ltd, Building 2 Granta Centre, Granta Park, Cambridge, United Kingdom
| | - Nadia Soliman
- Imperial College London, Pain Research Group, Chelsea and Westminster Hospital, London, United Kingdom
| | - Barbara Namer
- Research Group Neuroscience of the Interdisziplinary Center for Clinical Research, University Hospital of the RWTH Aachen, Aachen, Germany
- Institute for Physiology, University Hospital of the RWTH Aachen, Aachen, Germany
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
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Resurgent neuropathic discharge: an obstacle to the therapeutic use of neuroma resection? Pain 2023; 164:349-361. [PMID: 35639421 DOI: 10.1097/j.pain.0000000000002704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 05/20/2022] [Indexed: 02/06/2023]
Abstract
ABSTRACT Ectopic discharge ("ectopia") in damaged afferent axons is a major contributor to chronic neuropathic pain. Clinical opinion discourages surgical resection of nerves proximal to the original injury site for fear of resurgence of ectopia and exacerbated pain. We tested this concept in a well-established animal neuroma model. Teased-fiber recordings were made of ectopic spontaneous discharge originating in the experimental nerve-end neuroma and associated dorsal root ganglia in rats that underwent either a single transection (with ligation) of the sciatic nerve or 2 consecutive transections separated by 7, 14, 21, or 30 days. Ectopia emerged in afferent A and C fibers after a single cut with kinetics anticipated from previous studies. When resection was performed during the early period of intense A-fiber activity, a brief period of resurgence was observed. However, resection of neuromas of more than 14 days was followed by low levels of activity with no indication of resurgence. This remained the case in trials out to 60 days after the first cut. Similarly, we saw no indication of resurgent ectopia originating in axotomized dorsal root ganglion neuronal somata and no behavioral reflection of resurgence. In summary, we failed to validate the concern that proximal resection of a problematic nerve would lead to intense resurgent ectopic discharge and pain. As the well-entrenched concept of resurgence is based more on case reports and anecdotes than on solid evidence, it may be justified to relax the stricture against resecting neuromas as a therapeutic strategy, at least within the framework of controlled clinical trials.
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Barakat N, Gorman MP, Benson L, Becerra L, Borsook D. Pain and spinal cord imaging measures in children with demyelinating disease. NEUROIMAGE-CLINICAL 2015; 9:338-47. [PMID: 26509120 PMCID: PMC4588416 DOI: 10.1016/j.nicl.2015.08.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/19/2015] [Accepted: 08/28/2015] [Indexed: 12/15/2022]
Abstract
Pain is a significant problem in diseases affecting the spinal cord, including demyelinating disease. To date, studies have examined the reliability of clinical measures for assessing and classifying the severity of spinal cord injury (SCI) and also to evaluate SCI-related pain. Most of this research has focused on adult populations and patients with traumatic injuries. Little research exists regarding pediatric spinal cord demyelinating disease. One reason for this is the lack of reliable and useful approaches to measuring spinal cord changes since currently used diagnostic imaging has limited specificity for quantitative measures of demyelination. No single imaging technique demonstrates sufficiently high sensitivity or specificity to myelin, and strong correlation with clinical measures. However, recent advances in diffusion tensor imaging (DTI) and magnetization transfer imaging (MTI) measures are considered promising in providing increasingly useful and specific information on spinal cord damage. Findings from these quantitative imaging modalities correlate with the extent of demyelination and remyelination. These techniques may be of potential use for defining the evolution of the disease state, how it may affect specific spinal cord pathways, and contribute to the management of pediatric demyelination syndromes. Since pain is a major presenting symptom in patients with transverse myelitis, the disease is an ideal model to evaluate imaging methods to define these regional changes within the spinal cord. In this review we summarize (1) pediatric demyelinating conditions affecting the spinal cord; (2) their distinguishing features; and (3) current diagnostic and classification methods with particular focus on pain pathways. We also focus on concepts that are essential in developing strategies for the detection, monitoring, treatment and repair of pediatric myelitis. Pain is a major presenting symptom in children with myelitis. Currently used imaging has limited sensitivity to myelin content. We provide a summary on pediatric demyelinating conditions. We review pain involvement and pathways affected by demyelination. We review imaging modalities for the diagnosis and monitoring of myelitis.
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Affiliation(s)
- Nadia Barakat
- Center for Pain and the Brain, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Mark P Gorman
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Leslie Benson
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Lino Becerra
- Center for Pain and the Brain, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA ; Department of Radiology, Boston Children's Hospital, Boston, MA, USA
| | - David Borsook
- Center for Pain and the Brain, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA ; Department of Radiology, Boston Children's Hospital, Boston, MA, USA
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Davies S, White R. Defning a holistic pain-relieving approach to wound care via a drug free polymeric membrane dressing. J Wound Care 2011; 20:250, 252, 254 passim. [DOI: 10.12968/jowc.2011.20.5.250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- S.L. Davies
- Institute of Science and the Environment, University of Worcester, UK
| | - R.J. White
- Institute of Health and Society, University of Worcester, UK
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Weragoda RMS, Ferrer E, Walters ET. Memory-like alterations in Aplysia axons after nerve injury or localized depolarization. J Neurosci 2005; 24:10393-401. [PMID: 15548654 PMCID: PMC6730315 DOI: 10.1523/jneurosci.2329-04.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Adaptive, long-term alterations of excitability have been reported in dendrites and presynaptic terminals but not along axons. Persistent enhancement of axonal excitability has been described in proximal nerve stumps at sites of nerve section in mammals, but this hyperexcitability is considered a pathological derangement important only as a cause of neuropathic pain. Identified neurons in Aplysia were used to test the hypothesis that either axonal injury or the focal depolarization that accompanies axonal injury can trigger a local decrease in action potential threshold [long-term hyperexcitability (LTH)] having memory-like properties. Nociceptive tail sensory neurons and a giant secretomotor neuron, R2, exhibited localized axonal LTH lasting 24 hr after a crush of the nerve or connective that severed the tested axons. Axons of tail sensory neurons and tail motor neurons, but not R2, displayed similar localized LTH after peripheral depolarization produced by 2 min exposure to elevated extracellular [K(+)]. Neither the induction nor expression of either form of LTH was blocked by saline containing 1% normal [Ca(2+)] during treatment or testing. However, both were prevented by local application of the protein synthesis inhibitors anisomycin or rapamycin. The features of (1) long-lasting alteration by localized depolarization, (2) restriction of alterations to intensely depolarized regions, and (3) dependence of the alterations on local, rapamycin-sensitive protein synthesis are shared with synaptic mechanisms considered important for memory formation. This commonality suggests that relatively simple, accessible axons may offer an opportunity to define fundamental plasticity mechanisms that were important in the evolution of memory.
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Affiliation(s)
- Ramal M S Weragoda
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, Houston, Texas 77030, USA
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Watkins LR, Maier SF. Beyond neurons: evidence that immune and glial cells contribute to pathological pain states. Physiol Rev 2002; 82:981-1011. [PMID: 12270950 DOI: 10.1152/physrev.00011.2002] [Citation(s) in RCA: 514] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Chronic pain can occur after peripheral nerve injury, infection, or inflammation. Under such neuropathic pain conditions, sensory processing in the affected body region becomes grossly abnormal. Despite decades of research, currently available drugs largely fail to control such pain. This review explores the possibility that the reason for this failure lies in the fact that such drugs were designed to target neurons rather than immune or glial cells. It describes how immune cells are a natural and inextricable part of skin, peripheral nerves, dorsal root ganglia, and spinal cord. It then examines how immune and glial activation may participate in the etiology and symptomatology of diverse pathological pain states in both humans and laboratory animals. Of the variety of substances released by activated immune and glial cells, proinflammatory cytokines (tumor necrosis factor, interleukin-1, interleukin-6) appear to be of special importance in the creation of peripheral nerve and neuronal hyperexcitability. Although this review focuses on immune modulation of pain, the implications are pervasive. Indeed, all nerves and neurons regardless of modality or function are likely affected by immune and glial activation in the ways described for pain.
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Affiliation(s)
- Linda R Watkins
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado.
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Chacur M, Milligan ED, Gazda LS, Armstrong C, Wang H, Tracey KJ, Maier SF, Watkins LR. A new model of sciatic inflammatory neuritis (SIN): induction of unilateral and bilateral mechanical allodynia following acute unilateral peri-sciatic immune activation in rats. Pain 2001; 94:231-244. [PMID: 11731060 DOI: 10.1016/s0304-3959(01)00354-2] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Immune activation near healthy peripheral nerves may have a greater role in creating pathological pain than previously recognized. We have developed a new model of sciatic inflammatory neuritis to assess how such immune activation may influence somatosensory processing. The present series of experiments reveal that zymosan (yeast cell walls) acutely injected around the sciatic nerve of awake unrestrained rats rapidly (within 3h) produces low threshold mechanical allodynia in the absence of thermal hyperalgesia. Low (4 microg) doses of zymosan produce both territorial and extra-territorial allodynia restricted to the ipsilateral hindpaw. Higher (40-400 microg) doses of zymosan again produce both territorial and extra-territorial allodynia. However, allodynia is now expressed both in the ipsilateral as well as contralateral hindpaws. Several lines of evidence are provided that the appearance of this contralateral ('mirror') allodynia reflects local actions of zymosan on the sciatic nerve rather than spread of this immune activator to the general circulation. Since many clinical neuropathies result from inflammation/infection of peripheral nerves rather than frank physical trauma, understanding how immune activation alters pain processing may suggest novel approaches to pain control.
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Affiliation(s)
- Marucia Chacur
- Laboratory of Pathophysiology, Butantan Institute, Avenue Vital Brazil, 1500, 05503-900 Sao Paulo, SP, Brazil Department of Psychology and the Center for Neurosciences, University of Colorado at Boulder, Boulder, CO 80309-0345, USA Laboratory of Biomedical Science, North Shore University Hospital, 350 Community Drive, Manhasset, NY 11030, USA
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Sutton JL, Maccecchini ML, Kajander KC. The kainate receptor antagonist 2S,4R-4-methylglutamate attenuates mechanical allodynia and thermal hyperalgesia in a rat model of nerve injury. Neuroscience 1999; 91:283-92. [PMID: 10336078 DOI: 10.1016/s0306-4522(98)00621-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Opioids and receptor antagonists of excitatory amino acids attenuate mechanical allodynia and thermal hyperalgesia in animal models of neuropathic pain. Recently, a kainate receptor antagonist, 2S,4R-4-methylglutamate, has been developed but has not been tested for antinociceptive effects in animal models of neuropathic pain. We evaluated whether 2S,4R-4-methylglutamate attenuated responses to mechanical and thermal stimuli in uninjured (control) rats and increased responsiveness in rats with chronic constriction injury. Rats were tested for a number of withdrawal responses using a calibrated von Frey filament (mechanical stimulus) and withdrawal latencies from a radiant heat source (thermal stimulus). In control rats, 2S,4R-4-methylglutamate produced a small but significant decrease in responses from the mechanical stimulus (25 mg/kg) and significantly increased withdrawal latencies from the thermal stimulus at the highest dose administered (100 mg/kg). In addition, 2S,4R-4-methylglutamate greatly attenuated increased responsiveness in rats with chronic constriction injury. At four to eight days following chronic constriction injury, animals that displayed increased responsiveness to mechanical and thermal stimuli were injected intraperitoneally with either dizocilpine maleate (0.1 mg/kg), morphine (4 mg/kg), vehicle as controls, or 2S,4R-4-methylglutamate (25, 50, 75 or 100 mg/kg). 2S,4R-4-Methylglutamate (25, 50, 75 and 100 mg/kg) significantly attenuated the frequency of responses to mechanical stimuli (Wilcoxon, P < 0.05) and the latency of responses to thermal stimuli (analysis of variance and Duncan's, P < 0.05). Dizocilpine maleate and morphine, as expected, also reduced these responses. These results suggest that, in addition to opioid and N-methyl-D-aspartate receptors, kainate receptors may play a role in the maintenance of mechanical allodynia and thermal hyperalgesia associated with peripheral nerve injury.
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Affiliation(s)
- J L Sutton
- Department of Oral Science, University of Minnesota, Minneapolis 55455, USA
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Jiang PJ, Terashima S. Selective labeling of [3H]2-deoxy-D-glucose in the snake trigeminal system: basal and infrared-stimulated conditions. Somatosens Mot Res 1995; 12:299-307. [PMID: 8834303 DOI: 10.3109/08990229509093663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
[3H]2-Deoxy-D-glucose (2-DG) and high-resolution autoradiography were employed to investigate labeling patterns of the trigeminal and infrared sensory system in a crotaline snake, the pit viper (Trimeresurus flavoviridis). Following intracardiac injection of 9.25 MBq [3H]2-DG, neurons in the nucleus of the lateral descending trigeminal tract (LTTD), nucleus reticularis caloris (RC), nucleus trigemini mesencephalicus, nucleus trigemini motorius, and trigeminal ganglia were labeled in various degrees after the pit organ had been removed (basal condition). This revealed that a higher rate of glucose utilization occurred in these nuclei than in the common sensory trigeminal nuclei, which lacked labeling entirely. When a pit was stimulated periodically with an infrared stimulus for 45 min, the difference in percentage of labeled cells was ipsilaterally increased by 12.84% in large cells of the LTTD and by 7.55% in the RC, as compared with the contralateral, basal-condition side. These slight changes indicate a small increase of glucose consumption during infrared reception. On the other hand, the small cells in the LTTD showed labeling that did not change with stimulation, suggesting that 2-DG uptake in inhibitory interneurons is relatively constant.
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Affiliation(s)
- P J Jiang
- Department of Physiology, University of the Ryukyus School of Medicine, Okinawa, Japan
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Abstract
Using the teased fiber recording method, we have compared pathophysiological properties of afferent axons injured in the infraorbital nerve (ION) vs the sciatic nerve in rats. Both myelinated and unmyelinated axons ending in ION neuromas produced much less ongoing discharge than those ending in sciatic nerve neuromas. Similarly, mechanosensitivity and acute injury discharge in ION neuromas were minimal. These differences may be related to the different spectrum of neuropathic symptomatology associated with nerve injury in the trigeminal vs the segmental innervation fields.
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Affiliation(s)
- M Tal
- Department of Anatomy, Hadassah - Hebrew University Medical School, Jerusalem, Israel
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