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Liao Z, Umar M, Huang X, Qin L, Xiao G, Chen Y, Tong L, Chen D. Transient receptor potential vanilloid 1: A potential therapeutic target for the treatment of osteoarthritis and rheumatoid arthritis. Cell Prolif 2024; 57:e13569. [PMID: 37994506 PMCID: PMC10905355 DOI: 10.1111/cpr.13569] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 10/11/2023] [Accepted: 10/15/2023] [Indexed: 11/24/2023] Open
Abstract
This study aims to determine the molecular mechanisms and analgesic effects of transient receptor potential vanilloid 1 (TRPV1) in the treatments of osteoarthritis (OA) and rheumatoid arthritis (RA). We summarize and analyse current studies regarding the biological functions and mechanisms of TRPV1 in arthritis. We search and analyse the related literature in Google Scholar, Web of Science and PubMed databases from inception to September 2023 through the multi-combination of keywords like 'TRPV1', 'ion channel', 'osteoarthritis', 'rheumatoid arthritis' and 'pain'. TRPV1 plays a crucial role in regulating downstream gene expression and maintaining cellular function and homeostasis, especially in chondrocytes, synovial fibroblasts, macrophages and osteoclasts. In addition, TRPV1 is located in sensory nerve endings and plays an important role in nerve sensitization, defunctionalization or central sensitization. TRPV1 is a non-selective cation channel protein. Extensive evidence in recent years has established the significant involvement of TRPV1 in the development of arthritis pain and inflammation, positioning it as a promising therapeutic target for arthritis. TRPV1 likely represents a feasible therapeutic target for the treatment of OA and RA.
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Affiliation(s)
- Zhidong Liao
- Department of Bone and Joint Surgerythe First Affiliated Hospital of Guangxi Medical UniversityNanningChina
- Research Center for Computer‐aided Drug Discovery, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
- Faculty of Pharmaceutical SciencesShenzhen Institute of Advanced TechnologyShenzhenChina
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co‐constructed by the Province and MinistryGuangxi Medical UniversityNanningGuangxiChina
| | - Muhammad Umar
- Research Center for Computer‐aided Drug Discovery, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
- Faculty of Pharmaceutical SciencesShenzhen Institute of Advanced TechnologyShenzhenChina
| | - Xingyun Huang
- Research Center for Computer‐aided Drug Discovery, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
- Faculty of Pharmaceutical SciencesShenzhen Institute of Advanced TechnologyShenzhenChina
| | - Ling Qin
- Musculoskeletal Research Laboratory of Department of Orthopaedics & Traumatology and Innovative Orthopaedic Biomaterial & Drug Translational Research LaboratoryLi Ka Shing Institute of Health Sciences, The Chinese University of Hong KongHong KongChina
| | - Guozhi Xiao
- School of MedicineSouthern University of Science and TechnologyShenzhenChina
| | - Yan Chen
- Department of Bone and Joint Surgerythe First Affiliated Hospital of Guangxi Medical UniversityNanningChina
| | - Liping Tong
- Research Center for Computer‐aided Drug Discovery, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
| | - Di Chen
- Research Center for Computer‐aided Drug Discovery, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
- Faculty of Pharmaceutical SciencesShenzhen Institute of Advanced TechnologyShenzhenChina
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Xu G, Xu S, Gong W, Dong S, Yu H. Low Trend for VZV-Associated Disease Patients to Visit Neurologists. J Multidiscip Healthc 2023; 16:1379-1392. [PMID: 37215749 PMCID: PMC10199679 DOI: 10.2147/jmdh.s412398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
Background Herpes zoster (HZ) is a skin disease that can also cause virus-infectious peripheral neuropathies. Despite this, there is limited information on patient preferences for seeking medical attention for HZ and zoster-associated pain (ZAP). Our study aimed to evaluate how frequently patients with ZAP choose to visit neurologists for their symptoms. Methods This study conducted a retrospective review of electronic health records in three general hospitals from January 2017 to June 2022. Using association rule mining, the study analyzed referral behaviors. Results We identified 33,633 patients with 111,488 outpatient visits over 5.5 years. The study found that the majority of patients (74.77-91.22%) visited dermatologists during their first outpatient visit, while only a small percentage (0.86-1.47%) preferred to consult a neurologist. The proportion of patients referred to a specialist during their medical visit varied significantly between different specialties within the same hospital (p <0.05) and even within the same specialty (p<0.05). There was a weak association (Lift:1.00-1.17) of referral behaviors between dermatology and neurology. Across the three hospitals, the average number of visits to a neurologist for ZAP was 1.42-2.49, with an average electronic health record duration of 11-15 days per patient. After consulting with a neurologist, some patients were referred to other specialists. Conclusion It was observed that patients with HZ and ZAP tended to visit a variety of specialists, with only a small number seeking the assistance of neurologists. However, from the perspective of neuroprotection, it is the duty of neurologists to provide more means.
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Affiliation(s)
- Gang Xu
- Department of Rehabilitation Medicine, Affiliated Tenth People’s Hospital of Tongji University, Shanghai Tenth People’s Hospital, Shanghai, 20072, People’s Republic of China
- Department of Rehabilitation Medicine, Tongji University School of Medicine, Shanghai, 200092, People’s Republic of China
| | - Site Xu
- Division of Information and Statistics, Affiliated Ruijin Hospital of Shanghai Jiaotong University School of Medicine, Shanghai, People’s Republic of China
| | - Weiwei Gong
- Department of Rehabilitation Medicine, Tongji University School of Medicine, Shanghai, 200092, People’s Republic of China
- Department of Rehabilitation Medicine, Shanghai First Rehabilitation Hospital, Shanghai, 200090, People’s Republic of China
| | - Shihong Dong
- Department of Rehabilitation Medicine, Tongji University School of Medicine, Shanghai, 200092, People’s Republic of China
| | - Hecheng Yu
- Department of Rehabilitation Medicine, Affiliated Tenth People’s Hospital of Tongji University, Shanghai Tenth People’s Hospital, Shanghai, 20072, People’s Republic of China
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Niimi Y, Gomez-Tames J, Wasaka T, Hirata A. Selective stimulation of nociceptive small fibers during intraepidermal electrical stimulation: Experiment and computational analysis. Front Neurosci 2023; 16:1045942. [PMID: 36711140 PMCID: PMC9880216 DOI: 10.3389/fnins.2022.1045942] [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: 09/16/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023] Open
Abstract
Electrical stimulation of skin nociceptors is gaining attention in pain research and peripheral neuropathy diagnosis. However, the optimal parameters for selective stimulation are still difficult to determine because they require simultaneous characterization of the electrical response of small fibers (Aδ- and C-fibers). In this study, we measured the in vivo electrical threshold responses of small fibers to train-pulse stimulation in humans for the first time. We also examined selective stimulation via a computational model, which combines electrical analysis, and terminal fiber and synaptic models, including the first cutaneous pain C-fiber model. Selective stimulation of small fibers is performed by injecting train-pulse stimulation via coaxial electrodes with an intraepidermal needle tip at varying pulse counts and frequencies. The activation Aδ- or C-fibers was discriminated from the differences in reaction time. Aδ-fiber elicited a pinpricking sensation with a mean reaction time of 0.522 s, and C-fiber elicited a tingling sensation or slight burning itch with a mean reaction time of 1.243 s. The implemented multiscale electrical model investigates synaptic effects while considering stimulation waveform characteristics. Experimental results showed that perception thresholds decreased with the number of consecutive pulses and frequency up to convergence (five pulses or 70 Hz) during the selective stimulation of Aδ- and C-fibers. Considering the synaptic properties, the optimal stimulus conditions for selective stimulation of Aδ- vs. C-fibers were train of at least four pulses and a frequency of 40-70 Hz at a pulse width of 1 ms. The experimental results were modeled with high fidelity by incorporating temporal synaptic effects into the computational model. Numerical analysis revealed terminal axon thickness to be the most important biophysical factor affecting threshold variability. The computational model can be used to estimate perception thresholds while understanding the mechanisms underlying the selective stimulation of small fibers. The parameters derived here are important in exploring selective stimulation between Aδ- and C-fibers for diagnosing neuropathies.
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Affiliation(s)
- Yuki Niimi
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Jose Gomez-Tames
- Center for Frontier Medical Engineering, Chiba University, Chiba, Japan
| | - Toshiaki Wasaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan,*Correspondence: Akimasa Hirata,
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Javed H, Johnson AM, Challagandla AK, Emerald BS, Shehab S. Cutaneous Injection of Resiniferatoxin Completely Alleviates and Prevents Nerve-Injury-Induced Neuropathic Pain. Cells 2022; 11:cells11244049. [PMID: 36552812 PMCID: PMC9776507 DOI: 10.3390/cells11244049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/29/2022] [Accepted: 12/09/2022] [Indexed: 12/16/2022] Open
Abstract
Fifth lumbar (L5) nerve injury in rodent produces neuropathic manifestations in the corresponding hind paw. The aim of this study was to investigate the effect of cutaneous injection of resiniferatoxin (RTX), a TRPV1 receptor agonist, in the rat's hind paw on the neuropathic pain induced by L5 nerve injury. The results showed that intraplantar injection of RTX (0.002%, 100 µL) (1) completely reversed the development of chronic thermal and mechanical hypersensitivity; (2) completely prevented the development of nerve-injury-induced thermal and mechanical hypersensitivity when applied one week earlier; (3) caused downregulation of nociceptive pain markers, including TRPV1, IB4 and CGRP, and upregulation of VIP in the ipsilateral dorsal horn of spinal cord and dorsal root ganglion (DRG) immunohistochemically and a significant reduction in the expression of TRPV1 mRNA and protein in the ipsilateral DRG using Western blot and qRT-PCR techniques; (4) caused downregulation of PGP 9.5- and CGRP-immunoreactivity in the injected skin; (5) produced significant suppression of c-fos expression, as a neuronal activity marker, in the spinal neurons in response to a second intraplantar RTX injection two weeks later. This work identifies the ability of cutaneous injection of RTX to completely alleviate and prevent the development of different types of neuropathic pain in animals and humans.
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Carroll L, Sandy-Hindmarch O, Baskozos G, Zhu GC, McCarthy J, Schmid A. Cutaneous expression of growth-associated protein 43 is not a compelling marker for human nerve regeneration in carpal tunnel syndrome. PLoS One 2022; 17:e0277133. [PMID: 36383568 PMCID: PMC9668135 DOI: 10.1371/journal.pone.0277133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 10/20/2022] [Indexed: 11/18/2022] Open
Abstract
Growth-associated protein 43 (GAP-43) has long been used as a marker for nerve regeneration following nerve injury, with numerous in vitro and animal studies showing its upregulation in regenerating neurons. In humans, expression of GAP-43 has predominantly been examined in skin biopsies from patients with peripheral neuropathies; with several studies showing a reduction in GAP-43 immunoreactive cutaneous nerve fibres. However, it remains elusive whether cutaneous GAP-43 is a valid marker for human nerve regeneration. Here, we present a cohort of 22 patients with electrodiagnostically confirmed carpal tunnel syndrome (CTS), used as a model system for focal nerve injury and neural regeneration after decompression surgery. We evaluate GAP-43 immunoreactivity and RNA expression levels in finger skin biopsies taken before and 6 months after surgery, relative to healthy controls. We further classify patients as 'regenerators' or 'non-regenerators' based on post-surgical epidermal re-innervation. We demonstrate that patients with CTS have lower GAP-43 positive intra-epidermal nerve fibre density (IENFD) before surgery than healthy controls. However, this difference disappears when normalising for total IENFD. Of note, we found surgery did not change GAP-43 expression in IENF, with no differences both in patients who were classified as regenerators and non-regenerators. We also did not identify pre-post surgical differences in cutaneous GAP-43 gene expression or associations with regeneration. These findings suggest cutaneous GAP-43 may not be a compelling marker for nerve regeneration in humans.
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Affiliation(s)
- Liam Carroll
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Oliver Sandy-Hindmarch
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Georgios Baskozos
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Guan Cheng Zhu
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Julia McCarthy
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Annina Schmid
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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Anand P, Privitera R, Donatien P, Fadavi H, Tesfaye S, Bravis V, Misra VP. Reversing painful and non-painful diabetic neuropathy with the capsaicin 8% patch: Clinical evidence for pain relief and restoration of function via nerve fiber regeneration. Front Neurol 2022; 13:998904. [PMID: 36388188 PMCID: PMC9643187 DOI: 10.3389/fneur.2022.998904] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/07/2022] [Indexed: 10/21/2023] Open
Abstract
Introduction Current oral treatments for pain in diabetic peripheral neuropathy (DPN) do not affect the progression of DPN i.e., "disease modification." We assessed whether Capsaicin 8% patch treatment can provide pain relief and also restore nerve density and function via nerve regeneration, in both painful (PDPN) and non-painful (NPDPN) diabetic peripheral neuropathy. Methods 50 participants with PDPN were randomized to receive Capsaicin 8% patch Qutenza with Standard of Care (SOC) (PDPN Q+SOC group), or SOC alone (PDPN SOC group). Pain symptoms were assessed with a diary (Numerical Pain Rating Scale, NRPS) and questionnaires. Investigations included quantitative sensory testing (QST) and distal calf skin biopsies, at baseline and 3 months after baseline visit; subsequent options were 3-monthly visits over 1 year. 25 participants with NPDPN had tests at baseline, and 3 months after all received Capsaicin 8% patch treatment. Results At 3 months after baseline, PDPN Q+SOC group had reduction in NPRS score (p = 0.0001), but not PDPN SOC group. Short-Form McGill Pain Questionnaire (SF-MPQ) showed significant reductions in scores for overall and other pain descriptors only in the PDPN Q+SOC group. Warm perception thresholds were significantly improved only in the PDPN Q+SOC group (p = 0.02), and correlated with reduction in SF-MPQ overall pain score (p = 0.04). NPDPN Q+SOC group did not report pain during the entire study. Density of intra-epidermal nerve fibers (IENF) with PGP9.5 was increased at 3 months in PDPN Q+SOC (p = 0.0002) and NPDPN Q+SOC (p = 0.002) groups, but not in the PDPN SOC group. Increased sub-epidermal nerve fibers (SENF) were observed with GAP43 (marker of regenerating nerve fibers) only in PDPN Q+SOC (p = 0.003) and NPDPN Q+SOC (p = 0.0005) groups. Pain relief in the PDPN Q+SOC group was correlated with the increased PGP9.5 IENF (p = 0.0008) and GAP43 (p = 0.004), whereas those with lack of pain relief showed no such increase; in some subjects pain relief and increased nerve fibers persisted over months. PGP9.5 IENF increase correlated with axon-reflex vasodilatation in a NPDPN Q+SOC subset (p = 0.006). Conclusions Capsaicin 8% patch can provide pain relief via nerve regeneration and restoration of function in DPN (disease modification). It may thereby potentially prevent diabetic foot complications, including ulcers.
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Affiliation(s)
- Praveen Anand
- Division of Neurology, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Rosario Privitera
- Division of Neurology, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Philippe Donatien
- Division of Neurology, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Hassan Fadavi
- Division of Neurology, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Solomon Tesfaye
- Diabetes Research Unit, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom
| | - Vassiliki Bravis
- Department of Endocrinology and Diabetes, St Mary's Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - V. Peter Misra
- Division of Neurology, Hammersmith Hospital, Imperial College London, London, United Kingdom
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Wold A, Rådman L, Norman K, Olausson H, Thordstein M. Clinical Evaluation of Nerve Function in Electrical Accident Survivors with Persisting Neurosensory Symptoms. Brain Sci 2022; 12:brainsci12101301. [PMID: 36291235 PMCID: PMC9599311 DOI: 10.3390/brainsci12101301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/14/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
Objective: Work related electrical accidents are prevalent and can cause persisting symptoms. We used clinical neurophysiological techniques to assess neurosensory function following electrical accidents and correlated test results with the patients’ symptoms. Methods: We studied 24 patients who reported persisting neurosensory symptoms following a workplace electrical accident. We assessed nerve function using quantitative sensory testing (QST), thermal roller testing, laser evoked potential (LEP), and electroneurography. The patients’ results were compared with previously established normative data. Results: Altogether, 67% of the patients showed at least one neurosensory impairment with a large heterogeneity in test results across patients. At a group level, we observed significant deviations in in QST, LEP, and sensory and motor neurography. Overall, we found a weak correlation between test results and self-reported symptoms. Conclusions: In a majority of patients with neurosensory symptoms after a workplace electrical accident, neurosensory testing confirmed the existence of an underlying impairment of the nervous system.
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Affiliation(s)
- Andrew Wold
- University Health Care Research Centre, Faculty of Medicine and Health, Örebro University, 70182 Örebro, Sweden
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, 58185 Linköping, Sweden
- Correspondence:
| | - Lisa Rådman
- University Health Care Research Centre, Faculty of Medicine and Health, Örebro University, 70182 Örebro, Sweden
- Department of Physiotherapy, Faculty of Medicine and Health, Örebro University, 70182 Örebro, Sweden
| | - Kerstin Norman
- National Unit for Health and Safety, Swedish Police Authority, 10226 Stockholm, Sweden
| | - Håkan Olausson
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, 58185 Linköping, Sweden
- Neuro, Biomedical and Clinical Sciences, Linköping University, 58185 Linköping, Sweden
| | - Magnus Thordstein
- Neuro, Biomedical and Clinical Sciences, Linköping University, 58185 Linköping, Sweden
- Department of Clinical Neurophysiology, Region Östergötland University Hospital, 58185 Linköping, Sweden
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8
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Just Breathe: Improving LEP Outcomes through Long Interval Breathing. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2022. [DOI: 10.3390/ctn6020013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Laser-evoked potentials (LEPs) constitute an objective clinical diagnostic method used to investigate the functioning of the nociceptor system, including signaling in thin peripheral nerve fibers: Aδ and C fibers. There is preliminary evidence that phase locking LEPs with the breathing cycle can improve the parameters used to evaluate LEPs. Methods: We tested a simple breathing protocol as a low-cost improvement to LEP testing of the hands. Twenty healthy participants all underwent three variants of LEP protocols: following a video-guided twelve-second breathing instruction, watching a nature video, or using the classic LEP method of focusing on the hand being stimulated. Results: The breath protocol produced significantly shorter latencies as compared with the nature or classic protocol. It was also the least prone to artifacts and was deemed most acceptable by the subjects. There was no difference between the protocols regarding LEP amplitudes. Conclusions: Using a breathing video can be a simple, low-cost improvement for LEP testing in research and clinical diagnostics.
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Raabe W, Walk D. Median amplitude and frequency analysis of sensory nerve responses to intraepidermal stimulation. J Neurosci Methods 2022; 365:109377. [PMID: 34634281 DOI: 10.1016/j.jneumeth.2021.109377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 11/16/2022]
Abstract
BACKGROUND In clinical practice, small myelinated sensory fibers conveying pain and other sensations, Aδ-fibers, cannot be examined with available nerve conduction study techniques. NEW METHOD Equipment available in clinical neurophysiology laboratories is used to record from human sensory nerves multiple averaged responses to non-painful stimulation of intraepidermal nerves. Ten averaged responses are analyzed in all possible pair combinations with an algorithm applied to a 0.45 ms period of amplitude and frequency (power spectrum). The median of the algorithms is compared to control data to identify potentials generated as response to intraepidermal stimulation. RESULTS Median analysis of the algorithm applied to amplitude and frequency of multiple record pairs identifies potentials with conduction velocities of Aδ-fibers. The analysis of frequency (power spectrum) adds data to the analysis of amplitude. Median analysis of multiple record pairs yields more data than analysis of one pair of alternate averages with the same algorithms. COMPARISON WITH EXISTING METHOD(S) At present, analysis of one pair of alternate average records with an algorithm is the only method to identify Aδ-fiber generated potentials. Median analysis of the same algorithm applied to the amplitude of multiple record pairs increases the number of Aδ-fiber generated potentials identified. Neither median analysis of amplitude nor frequency of multiple records pairs has ever been used for conduction studies of nerve fibers, including Aδ-fibers. CONCLUSIONS Stimulation, recording and data analysis methods used in this study can be applied in the clinical EMG laboratory to identify the conduction velocities of Aδ-fibers in human sensory nerves.
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Affiliation(s)
- W Raabe
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA.
| | - D Walk
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA
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Enhanced Ocular Surface and Intraoral Nociception via a Transient Receptor Potential Vanilloid 1 Mechanism in a Rat Model of Obstructive Sleep Apnea. Neuroscience 2021; 483:66-81. [PMID: 34883200 DOI: 10.1016/j.neuroscience.2021.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/29/2021] [Accepted: 12/01/2021] [Indexed: 12/28/2022]
Abstract
Obstructive sleep apnea (OSA), characterized by low arterial oxygen saturation during sleep, is associated with an increased risk of orofacial pain. In this study, we simulated chronic intermittent hypoxia (CIH) during the sleep/rest phase (light phase) to determine the role of transient receptor potential vanilloid 1 (TRPV1) in mediating enhanced orofacial nocifensive behavior and trigeminal spinal subnucleus caudalis (Vc) neuronal responses to capsaicin (a TRPV1 agonist) stimulation in a rat model of OSA. Rats were subjected to CIH (nadir O2, 5%) during the light phase for 8 or 16 consecutive days. CIH yielded enhanced behavioral responses to capsaicin after application to the ocular surface and intraoral mucosa, which was reversed under normoxic conditions. The percentage of TRPV1-immunoreactive trigeminal ganglion neurons was greater in CIH rats than in normoxic rats and recovered under normoxic conditions after CIH. The ratio of large-sized TRPV1-immunoreactive trigeminal ganglion neurons increased in CIH rats. The density of TRPV1 positive primary afferent terminals in the superficial laminae of Vc was higher in CIH rats. Phosphorylated extracellular signal-regulated kinase (pERK)-immunoreactive cells intermingled with the central terminal of TRPV1-positive afferents in the Vc. The number of pERK-immunoreactive cells following low-dose capsaicin (0.33 µM) application to the tongue was significantly greater in the middle portion of the Vc of CIH rats than of normoxic rats and recovered under normoxic conditions after CIH. These data suggest that CIH during the sleep (light) phase is sufficient to transiently enhance pain on the ocular surface and intraoral mucosa via TRPV1-dependent mechanisms.
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Sensory defunctionalization induced by 8% topical capsaicin treatment in a model of ultraviolet-B-induced cutaneous hyperalgesia. Exp Brain Res 2021; 239:2873-2886. [PMID: 34302514 DOI: 10.1007/s00221-021-06170-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 07/02/2021] [Indexed: 10/20/2022]
Abstract
Subpopulations of primary nociceptors (C- and Aδ-fibers), express the TRPV1 receptor for heat and capsaicin. During cutaneous inflammation, these afferents may become sensitized, leading to primary hyperalgesia. It is known that TRPV1+ nociceptors are involved in heat hyperalgesia; however, their involvement in mechanical hyperalgesia is unclear. This study explored the contribution of capsaicin-sensitive nociceptors in the development of mechanical and heat hyperalgesia in humans following ultraviolet-B (UVB) irradiation. Skin areas in 18 healthy volunteers were randomized to treatment with 8% capsaicin/vehicle patches for 24 h. After patches removal, one capsaicin-treated area and one vehicle area were irradiated with 2xMED (minimal erythema dose) of UVB. 1, 3 and 7 days post-UVB exposure, tests were performed to evaluate the development of UVB-induced cutaneous hyperalgesia: thermal detection and pain thresholds, pain sensitivity to supra-threshold heat stimuli, mechanical pain threshold and sensitivity, touch pleasantness, trans-epidermal water loss (TEWL), inflammatory response, pigmentation and micro-vascular reactivity. Capsaicin pre-treatment, in the UVB-irradiated area (Capsaicin + UVB area), increased heat pain thresholds (P < 0.05), and decreased supra-threshold heat pain sensitivity (P < 0.05) 1, 3 and 7 days post-UVB irradiation, while mechanical hyperalgesia resulted unchanged (P > 0.2). No effects of capsaicin were reported on touch pleasantness (P = 1), TEWL (P = 0.31), inflammatory response and pigmentation (P > 0.3) or micro-vascular reactivity (P > 0.8) in response to the UVB irradiation. 8% capsaicin ablation predominantly defunctionalizes TRPV1+-expressing cutaneous nociceptors responsible for heat pain transduction, suggesting that sensitization of these fibers is required for development of heat hyperalgesia following cutaneous UVB-induced inflammation but they are likely only partially necessary for the establishment of robust primary mechanical hyperalgesia.
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12
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Lefaucheur JP, Abbas SA, Lefaucheur-Ménard I, Rouie D, Tebbal D, Bismuth J, Nordine T. Small nerve fiber selectivity of laser and intraepidermal electrical stimulation: A comparative study between glabrous and hairy skin. Neurophysiol Clin 2021; 51:357-374. [PMID: 34304975 DOI: 10.1016/j.neucli.2021.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 06/20/2021] [Accepted: 06/20/2021] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES In clinical neurophysiology practice, various methods of stimulation can be used to activate small-diameter nociceptive cutaneous afferents located in the epidermis. These methods include different types of laser and intraepidermal electrical stimulation techniques. The diffusion of the stimulation in the skin, inside or under the epidermis, depends on laser wavelength and electrode design, in particular. The aim of this study was to compare several of these techniques in their ability to selectively stimulate small nerve fibers. METHODS In 8 healthy subjects, laser stimulation (using a CO2 or Nd:YAP laser) and intraepidermal electrical stimulation (using a micropatterned, concentric planar, or concentric needle electrode), were applied at increasing energy or intensity on the dorsal or volar aspect of the right hand or foot. The subjects were asked to define the perceived sensation (warm, pinprick, or electric shock sensation, corresponding to the activation of C fibers, Aδ fibers, or Aβ fibers, respectively) after each stimulation. Depending on the difference in the sensations perceived between dorsal (hairy skin with thin stratum corneum) and volar (glabrous skin with thick stratum corneum) stimulations, the diffusion of the stimulation inside or under the epidermis and the nature of the activated afferents were determined. RESULTS Regarding laser stimulation, the perceived sensations turned from warm to pinprick with increasing energies of stimulation, in particular with the Nd:YAP laser, of which pulse could penetrate deep in the skin according to its short wavelength. In contrast, CO2 laser stimulation produced only warm sensations and no pricking sensation when applied to the glabrous skin, perhaps due to a thicker stratum corneum and the shallow penetration of the CO2 laser pulse. Regarding intraepidermal electrical stimulation using concentric electrodes, the perceived sensations turned from pinprick to a combination of pinprick and electrical shocks with increasing intensities. Using the concentric planar electrode, the sensations perceived at high stimulation intensity even consisted of electric shocks without concomitant pinprick. In contrast, using the micropatterned electrode, only pinprick sensations were produced by the stimulation of the hairy skin, while the stimulation of the glabrous skin produced no sensation at all within the limits of stimulation intensities used in this study. CONCLUSIONS Using the CO2 laser or the micropatterned electrode, pinprick sensations were selectively produced by the stimulation of hairy skin, while only warm sensation or no sensation at all were produced by the stimulation of glabrous skin. These two techniques appear to be more selective with a limited diffusion of the stimulation into the skin, restricting the activation of sensory afferents to the most superficial and smallest intraepidermal nerve fibers.
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Affiliation(s)
- Jean-Pascal Lefaucheur
- Univ Paris Est Creteil, EA4391, ENT, F-94010 Creteil, France; AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France.
| | - Samar A Abbas
- AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France
| | | | - Denis Rouie
- AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France
| | - Denise Tebbal
- AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France
| | - Julie Bismuth
- AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France
| | - Tarik Nordine
- Univ Paris Est Creteil, EA4391, ENT, F-94010 Creteil, France; AP-HP, Henri Mondor University Hospital, Clinical Neurophysiology Unit, F-94010 Creteil, France
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Kant V, Jangir BL, Sharma M, Kumar V, Joshi VG. Topical application of quercetin improves wound repair and regeneration in diabetic rats. Immunopharmacol Immunotoxicol 2021; 43:536-553. [PMID: 34278923 DOI: 10.1080/08923973.2021.1950758] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Purpose: There is an urgent need of effective drug/formulation to speed up the healing process in diabetic wounds. In our earlier studies, quercetin has accelerated the healing of nondiabetic wounds. So, we investigated the wound-healing potentials of quercetin in diabetic rats.Materials and methods: A square-shaped cutaneous wound (≈400 mm2) was created on the back of nondiabetic and diabetic rats. They were divided into three groups, viz. healthy control (nondiabetic), diabetic control and diabetic-treated group. Ointment base was topically applied for 21 days in healthy and diabetic control groups. Quercetin (0.3%) ointment was similarly applied in third group. Effects of quercetin on repair and regenerations of diabetic wounds in terms of wound closure, inflammation, angiogenesis, fibroblast proliferation, collagen synthesis, epithelialization, axonal regeneration etc was studied.Results: Quercetin accelerated the wound closure and increased the expressions of IL-10, VEGF and TGF-β1 in granulation/healing tissue of diabetic wound. However, quercetin decreased the expression of TNF-α, IL-1β, and MMP-9. Histopathological evaluation revealed amelioration of persistence of inflammatory cells by quercetin in diabetic wounds. There was good quality of granulation tissue, marked fibroblast proliferation, well organized collagen deposition, early regeneration of epithelial layer etc. in the quercetin treated diabetic wounds in comparison to diabetic control group. Results of immunohistochemistry showed more angiogenesis, faster phenotypic switching of fibroblast to myofibroblasts and increased GAP-43 positive nerve fibers in quercetin-treated diabetic wounds.Conclusion: Quercetin ointment at 0.3% w/w concentration modulates cytokines, growth factors and protease, thereby improved repair and regenerations of cutaneous diabetic wounds in rats.
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Affiliation(s)
- Vinay Kant
- Department of Veterinary Pharmacology and Toxicology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, Haryana, India
| | - Babu Lal Jangir
- Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, Haryana, India
| | - Maneesh Sharma
- Department of Veterinary Clinical Complex, College of Veterinary Sciences, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Vinod Kumar
- Department of Veterinary Pharmacology and Toxicology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, Haryana, India
| | - Vinay G Joshi
- Department of Animal Biotechnology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
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Tanaka S, Gomez-Tames J, Inui K, Ueno S, Hirata A, Wasaka T. Synaptic Effect of Aδ-Fibers by Pulse-Train Electrical Stimulation. Front Neurosci 2021; 15:643448. [PMID: 33981196 PMCID: PMC8107290 DOI: 10.3389/fnins.2021.643448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/29/2021] [Indexed: 11/17/2022] Open
Abstract
Electrical stimulation of specific small fibers (Aδ- and C-fibers) is used in basic studies on nociception and neuropathic pain and to diagnose neuropathies. For selective stimulation of small fibers, the optimal stimulation waveform parameters are an important aspect together with the study of electrode design. However, determining an optimal stimulation condition is challenging, as it requires the characterization of the response of the small fibers to electrical stimulation. The perception thresholds are generally characterized using single-pulse stimulation based on the strength-duration curve. However, this does not account for the temporal effects of the different waveforms used in practical applications. In this study, we designed an experiment to characterize the effects of multiple pulse stimulation and proposed a computational model that considers electrostimulation of fibers and synaptic effects in a multiscale model. The measurements of perception thresholds showed that the pulse dependency of the threshold was an exponential decay with a maximum reduction of 55%. In addition, the frequency dependence of the threshold showed a U-shaped response with a reduction of 25% at 30 Hz. Moreover, the computational model explained the synaptic effects, which were also confirmed by evoked potential recordings. This study further characterized the activation of small fibers and clarified the synaptic effects, demonstrating the importance of waveform selection.
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Affiliation(s)
- Shota Tanaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Jose Gomez-Tames
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Koji Inui
- Department of Functioning and Disability, Aichi Developmental Disability Center, Institute for Developmental Research, Kasugai, Japan.,Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Shoogo Ueno
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan.,Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan.,Frontier Research Institute for Information Science, Nagoya Institute of Technology, Nagoya, Japan
| | - Toshiaki Wasaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
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Neurophysiologic assessment of small fibre damage in chemotherapy-induced peripheral neuropathy. Clin Neurophysiol 2021; 132:1947-1956. [PMID: 34034962 DOI: 10.1016/j.clinph.2021.02.406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 02/16/2021] [Accepted: 02/28/2021] [Indexed: 11/23/2022]
Abstract
OBJECTIVE In patients with chemotherapy-induced peripheral neuropathy (CIPN), demonstration of small fibre (SF) damage is important to understand chronic late effects. METHODS Thirty patients having complaints compatible with possible CIPN following treatment with oxaliplatin or docetaxel were compared with 27 healthy subjects. All subjects were evaluated with quantitative sensory testing (QST) assessing SF function and laser evoked potentials (LEP). In addition, SF-damage was assessed using cutaneous silent periods evoked with electrical (El-CSP) and laser (Ls-CSP) stimuli. RESULTS For LEP, N2P2 amplitudes were significantly smaller in patients than controls in both upper (P = 0.007) and lower extremities (P = 0.002), and the N1 amplitude in upper extremities of patients were significantly smaller than in controls (P = 0.001). SF-QST, LEP, Ls-CSP, and El-CSP were abnormal in 10 (33.3%), 16 (53.3%), 19 (63.3%), and 24 (80%) of CIPN patients, respectively. CONCLUSIONS In patients with possible CIPN, El-CSP and Ls-CSP were more often abnormal than LEP and QST. This is probably because El-CSP and Ls-CSP inform mainly about peripheral nociceptive fibres, while LEP and QST inform about peripheral and central nociceptive pathways together. SIGNIFICANCE LEP and QST are established methods to detect SF-damage. El- and Ls-CSP might help clinicians in diagnosing SF-damage.
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16
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Capsaicin 8% patch Qutenza and other current treatments for neuropathic pain in chemotherapy-induced peripheral neuropathy (CIPN). Curr Opin Support Palliat Care 2021; 15:125-131. [PMID: 33905384 DOI: 10.1097/spc.0000000000000545] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE OF REVIEW Current oral treatments for neuropathic pain associated with chemotherapy-induced peripheral neuropathy (CIPN) have limited clinical efficacy, and undesirable side-effects. Topically delivered treatments have the advantage of avoiding CNS side-effects, while relieving pain. We have reviewed treatments of neuropathic pain associated with CIPN, focusing on the Capsaicin 8% patch, which can provide pain relief for up to 3 months or longer after a single 30-60-min application. RECENT FINDINGS Capsaicin 8% patch is a licensed treatment in the EU/UK for neuropathic pain and shown to be safe and effective in providing pain relief for patients with CIPN. Repeated daily oral or topical administrations are not required, as with other current treatments. The side-effects are transient and restricted to the time around patch application. New evidence suggests the Capsaicin 8% patch can promote the regeneration and restoration of skin nerve fibres in CIPN, in addition to the pain relief. SUMMARY The Capsaicin 8% patch is now often a preferred a treatment option for localised neuropathic pain conditions, including the feet and hands in patients with CIPN. Capsaicin 8% patch can be repeated three-monthly, if needed, for a year. In addition to pain relief, it may have a disease-modifying effect.
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17
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Wu CH, Wu MK, Lu CC, Tsai HP, Lu YY, Lin CL. Impact of Hepatoma-Derived Growth Factor Blockade on Resiniferatoxin-Induced Neuropathy. Neural Plast 2021; 2021:8854461. [PMID: 33727914 PMCID: PMC7937473 DOI: 10.1155/2021/8854461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/05/2021] [Accepted: 02/08/2021] [Indexed: 12/16/2022] Open
Abstract
Resiniferatoxin is an ultrapotent capsaicin analog that mediates nociceptive processing; treatment with resiniferatoxin can cause an inflammatory response and, ultimately, neuropathic pain. Hepatoma-derived growth factor, a growth factor related to normal development, is associated with neurotransmitters surrounding neurons and glial cells. Therefore, the study aims to investigate how blocking hepatoma-derived growth factor affects the inflammatory response in neuropathic pain. Serum hepatoma-derived growth factor protein expression was measured via ELISA. Resiniferatoxin was administrated intraperitoneally to induce neuropathic pain in 36 male Sprague-Dawley rats which were divided into three groups (resiniferatoxin+recombinant hepatoma-derived growth factor antibody group, resiniferatoxin group, and control group) (n = 12/group). The mechanical threshold response was tested with calibration forceps. Cell apoptosis was measured by TUNEL assay. Immunofluorescence staining was performed to detect apoptosis of neuron cells and proliferation of astrocytes in the spinal cord dorsal horn. RT-PCR technique and western blot were used to measure detect inflammatory factors and protein expressions. Serum hepatoma-derived growth factor protein expression was higher in the patients with sciatica compared to controls. In resiniferatoxin-group rats, protein expression of hepatoma-derived growth factor was higher than controls. Blocking hepatoma-derived growth factor improved the mechanical threshold response in rats. In dorsal root ganglion, blocking hepatoma-derived growth factor inhibited inflammatory cytokines. In the spinal cord dorsal horn, blocking hepatoma-derived growth factor inhibited proliferation of astrocyte, apoptosis of neuron cells, and attenuated expressions of pain-associated proteins. The experiment showed that blocking hepatoma-derived growth factor can prevent neuropathic pain and may be a useful alternative to conventional analgesics.
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Affiliation(s)
- Chieh-Hsin Wu
- Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
- Department of Surgery, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Ming-Kung Wu
- Department of Psychiatry, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
| | - Chun-Ching Lu
- Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, Taipei 112, Taiwan
- Faculty of Medicine, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Hung-Pei Tsai
- Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
| | - Ying-Yi Lu
- Department of Dermatology, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Shu-Zen Junior College of Medicine and Management, Kaohsiung 821, Taiwan
| | - Chih-Lung Lin
- Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
- Department of Surgery, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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18
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Tanaka S, Gomez-Tames J, Wasaka T, Inui K, Ueno S, Hirata A. Electrical Characterisation of Aδ-Fibres Based on Human in vivo Electrostimulation Threshold. Front Neurosci 2021; 14:588056. [PMID: 33584171 PMCID: PMC7873976 DOI: 10.3389/fnins.2020.588056] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/18/2020] [Indexed: 11/13/2022] Open
Abstract
Electrical stimulation of small fibres is gaining attention in the diagnosis of peripheral neuropathies, such as diabetes mellitus, and pain research. However, it is still challenging to characterise the electrical characteristics of axons in small fibres (Aδ and C fibres). In particular, in vitro measurement for human Aδ-fibre is difficult due to the presence of myelin and ethical reason. In this study, we investigate the in vivo electrical characteristics of the human Aδ-fibre to derive strength-duration (S-D) curves from the measurement. The Aδ-fibres are stimulated using coaxial planar electrodes with intraepidermal needle tip. For human volunteer experiments, the S-D curve of Aδ-fibre is obtained in terms of injected electrical current. With the computational analysis, the standard deviation of the S-D curve is mostly attributed to the thickness of the stratum corneum and depth of the needle tip, in addition to the fibre thickness. Then, we derive electrical parameters of the axon in the Aδ-fibre based on a conventional fibre model. The parameters derived here would be important in exploring the optimal stimulation condition of Aδ-fibres.
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Affiliation(s)
- Shota Tanaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Jose Gomez-Tames
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Toshiaki Wasaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Koji Inui
- Department of Functioning and Disability, Institute for Developmental Research, Aichi Developmental Disability Center, Kasugai, Japan
- Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Shoogo Ueno
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
- Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
- Frontier Research Institute for Information Science, Nagoya Institute of Technology, Nagoya, Japan
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19
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Wu Q, Bai P, Xia Y, Xia Y, Xu B, Dai K, Zheng Z, Guo MSS, Fung KWC, Dong TTX, Tsim KWK. Capsaicin Inhibits the Expression of Melanogenic Proteins in Melanocyte via Activation of TRPV1 Channel: Identifying an Inhibitor of Skin Melanogenesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:14863-14873. [PMID: 33280383 DOI: 10.1021/acs.jafc.0c06321] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Chili pepper belongs to the genus Capsicum of Solanaceae family. Capsaicin is the primary capsaicinoid in placenta and flesh of chili pepper fruit, which has been shown to have various pharmacological functions, including gastric protection, anti-inflammation, and obesity treatment. Here, we revealed that capsaicin as well as chilli extract was able to inhibit synthesis of melanin in melanocytes. In cultured melanocytes, the melanin content was reduced to 54 ± 6.55% and 42 ± 7.41% with p < 0.001 under treatment of 50 μM capsaicin for 24 and 72 h, respectively. In parallel, the protein levels of tyrosinase and tyrosinase-related protein-1 were reduced to 62 ± 8.35% and 48 ± 8.92% with p < 0.001. Such an inhibitory effect of capsaicin was mediated by activation of transient receptor potential vanilloid 1-induced phosphorylation of extracellular signal-regulated kinase. This resulted in a degradation of microphthalmia-associated transcription factor, leading to reduction of melanogenic enzymes and melanin. These results revealed that capsaicin could be an effective inhibitor for skin melanogenesis. Hence, chili pepper, as our daily food, has potential in dermatological application, and capsaicin should be considered as a safe agent in treating hyperpigmentation problems.
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Affiliation(s)
- Qiyun Wu
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Panzhu Bai
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Yiteng Xia
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Yingjie Xia
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Bowen Xu
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Kun Dai
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Zhongyu Zheng
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Maggie S S Guo
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Kelly W C Fung
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Tina T X Dong
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
| | - Karl W K Tsim
- Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China
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Fight fire with fire: Neurobiology of capsaicin-induced analgesia for chronic pain. Pharmacol Ther 2020; 220:107743. [PMID: 33181192 DOI: 10.1016/j.pharmthera.2020.107743] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022]
Abstract
Capsaicin, the pungent ingredient in chili peppers, produces intense burning pain in humans. Capsaicin selectively activates the transient receptor potential vanilloid 1 (TRPV1), which is enriched in nociceptive primary afferents, and underpins the mechanism for capsaicin-induced burning pain. Paradoxically, capsaicin has long been used as an analgesic. The development of topical patches and injectable formulations containing capsaicin has led to application in clinical settings to treat chronic pain conditions, such as neuropathic pain and the potential to treat osteoarthritis. More detailed determination of the neurobiological mechanisms of capsaicin-induced analgesia should provide the logical rationale for capsaicin therapy and help to overcome the treatment's limitations, which include individual differences in treatment outcome and procedural discomfort. Low concentrations of capsaicin induce short-term defunctionalization of nociceptor terminals. This phenomenon is reversible within hours and, hence, likely does not account for the clinical benefit. By contrast, high concentrations of capsaicin lead to long-term defunctionalization mediated by the ablation of TRPV1-expressing afferent terminals, resulting in long-lasting analgesia persisting for several months. Recent studies have shown that capsaicin-induced Ca2+/calpain-mediated ablation of axonal terminals is necessary to produce long-lasting analgesia in a mouse model of neuropathic pain. In combination with calpain, axonal mitochondrial dysfunction and microtubule disorganization may also contribute to the longer-term effects of capsaicin. The analgesic effects subside over time in association with the regeneration of the ablated afferent terminals. Further determination of the neurobiological mechanisms of capsaicin-induced analgesia should lead to more efficacious non-opioidergic analgesic options with fewer adverse side effects.
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Devigili G, Cazzato D, Lauria G. Clinical diagnosis and management of small fiber neuropathy: an update on best practice. Expert Rev Neurother 2020; 20:967-980. [PMID: 32654574 DOI: 10.1080/14737175.2020.1794825] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Small fiber neuropathy (SFN) is a heterogeneous group of disorders affecting thin myelinated Aδ and unmyelinated C fibers. Common symptoms include neuropathic pain and autonomic disturbances, and the typical clinical presentation is that of a length-dependent polyneuropathy, although other distributions could be present. AREA COVERED This review focuses on several aspects of SFN including etiology, clinical presentation, diagnostic criteria and tests, management, and future perspectives. Diagnostic challenges are discussed, encompassing the role of accurate and standardized assessment of symptoms and signs and providing clues for the clinical practice. The authors discuss the evidence in support of skin biopsy and quantitative sensory testing as diagnostic tests and present an overview of other diagnostic techniques to assess sensory and autonomic fibers dysfunction. The authors also suggest a systematic approach to the etiology including a set of laboratory tests and genetic examinations of sodium channelopathies and other rare conditions that might drive the therapeutic approach based on underlying cause or symptoms treatment. EXPERT OPINION SFN provides a useful model for neuropathic pain whose known mechanisms and cause could pave the way toward personalized treatments.
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Affiliation(s)
- Grazia Devigili
- Movement Disorders Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta" , Milan, Italy
| | - Daniele Cazzato
- Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta" , Milan, Italy
| | - Giuseppe Lauria
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta" , Milan, Italy.,Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan , Milan, Italy
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22
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Vecchio E, Lombardi R, Paolini M, Libro G, Delussi M, Ricci K, Quitadamo SG, Gentile E, Girolamo F, Iannone F, Lauria G, de Tommaso M. Peripheral and central nervous system correlates in fibromyalgia. Eur J Pain 2020; 24:1537-1547. [PMID: 32478943 DOI: 10.1002/ejp.1607] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 05/14/2020] [Accepted: 05/21/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Fibromyalgia (FM) is a syndrome characterized by altered pain processing at central and peripheral level, whose pathophysiologic mechanisms remain obscure. We aimed at exploring the structural changes of peripheral nociceptor measured by skin biopsy, the functional changes of central nociceptive pathway assessed by laser-evoked potentials (LEP), and their correlation with clinical features and comorbidities. METHODS In all, 81 patients diagnosed with FM underwent skin biopsies with quantification of intraepidermal nerve fibre density (IENFD) at the thigh and distal leg, and LEP recording by stimulating hand, thigh and foot. Nerve conduction study (NCS), clinical features, comorbidity with migraine and mood disorders, and previous, non-active immune-mediated disorders were recorded. RESULTS Intraepidermal nerve fibre density was reduced in 85% of patients at the thigh and in 12.3% of patients at the distal leg, whereas it was normal in 14.8% of patients. N2P2 habituation index from laser stimulation at the thigh was altered in 97.5% of patients and correlated with reduced IENFD at the thigh. LEP latencies and amplitudes did not differ among groups. No association was found between IENFD, LEP, clinical features and comorbidities. CONCLUSIONS Fibromyalgia patients most commonly showed a mild loss of peripheral nociceptors at the thigh rather than distal small fibre neuropathy. This finding was associated with an altered habituation index and strengthened the hypothesis that central sensitization plays a key role in the pathogenesis of the disease. SIGNIFICANCE Central impairment of pain processing likely underlies FM, which in most patients is associated with mild proximal small fibre pathology.
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Affiliation(s)
- Eleonora Vecchio
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Raffaella Lombardi
- 3rd Neurology Unit and Skin Biopsy, Department of Clinical Neurosciences, Peripheral Neuropathy and Neuropathic Pain Laboratory, IRCCS Foundation, 'Carlo Besta' Neurological Institute, Milan, Italy
| | - Matilde Paolini
- 3rd Neurology Unit and Skin Biopsy, Department of Clinical Neurosciences, Peripheral Neuropathy and Neuropathic Pain Laboratory, IRCCS Foundation, 'Carlo Besta' Neurological Institute, Milan, Italy
| | - Giuseppe Libro
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Marianna Delussi
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Katia Ricci
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Silvia G Quitadamo
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Eleonora Gentile
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Francesco Girolamo
- Unit of Human Anatomy and Histology, Department of Basic Medical Sciences, Neurosciences and Sensory Organs, School of Medicine, University of Bari, Bari, Italy
| | - Florenzo Iannone
- Rheumatology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Giuseppe Lauria
- 3rd Neurology Unit and Skin Biopsy, Department of Clinical Neurosciences, Peripheral Neuropathy and Neuropathic Pain Laboratory, IRCCS Foundation, 'Carlo Besta' Neurological Institute, Milan, Italy.,Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Milan, Italy
| | - Marina de Tommaso
- Applied Neurophysiology and Pain Unit, Department of Basic Medical Sciences Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
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Ablation of TRPV1+ Afferent Terminals by Capsaicin Mediates Long-Lasting Analgesia for Trigeminal Neuropathic Pain. eNeuro 2020; 7:ENEURO.0118-20.2020. [PMID: 32404326 PMCID: PMC7266139 DOI: 10.1523/eneuro.0118-20.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/22/2022] Open
Abstract
Trigeminal neuropathic pain (TNP) is often resistant to current pharmacotherapy, and there is a pressing need to develop more efficacious treatments. Capsaicin is a pungent ingredient of chili peppers and specifically activates transient receptor potential vanilloid subtype 1 (TRPV1), a Ca2+-permeable ion channel. Topical capsaicin invariably induces burning pain. Paradoxically, the transient pain is often followed by prolonged attenuation of the preexisting pathologic pain from the same region. However, the mechanisms underlying capsaicin-induced analgesia are not well understood. Although the reports of the involvement of TRPV1 and TRPV1+ afferents in neuropathic pain are controversial, we recently demonstrated that TRPV1 and TRPV1+ afferents are involved in mechanical hyperalgesia in mice with chronic constriction injury of the infraorbital nerve (ION-CCI). Consistently, chemogenetic inhibition of TRPV1-lineage (TRPV1-LN) afferents attenuated mechanical hyperalgesia and ongoing pain. In mice with ION-CCI, we found that a single focal injection of capsaicin into facial skin led to attenuation of mechanical hyperalgesia over two weeks. Capsaicin treatment also attenuated secondary hyperalgesia in extraterritorial mandibular skin. Furthermore, capsaicin treatment decreased ongoing pain. Longitudinal in vivo two-photon imaging of cutaneous nerve fibers showed that such capsaicin-induced analgesia is correlated with cutaneous nerve terminal density. Furthermore, preventing capsaicin-induced ablation of afferent terminals by co-administration of capsaicin with MDL28170, an inhibitor of calpain, abolished capsaicin-induced analgesia. These results suggest that a single focal injection of capsaicin induces long-lasting analgesia for neuropathic pain via selective ablation of TRPV1+ afferent terminals and that TRPV1+ afferents contribute to the maintenance of TNP.
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van Neerven SGA, Mouraux A. Capsaicin-Induced Skin Desensitization Differentially Affects A-Delta and C-Fiber-Mediated Heat Sensitivity. Front Pharmacol 2020; 11:615. [PMID: 32508630 PMCID: PMC7248294 DOI: 10.3389/fphar.2020.00615] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 04/20/2020] [Indexed: 12/19/2022] Open
Abstract
Localized neuropathic pain can be relieved following the topical application of high-concentration capsaicin. This clinical effect is thought to be related to the temporary desensitization of capsaicin- and heat-sensitive epidermal nociceptors. The objective of the present study was to examine whether the changes in thermal sensitivity induced by high-concentration topical capsaicin can be explained entirely by desensitization of capsaicin-sensitive afferents. For this purpose, we characterized, in 20 healthy human volunteers, the time course and spatial extent of the changes in sensitivity to thermal stimuli preferentially activating heat-sensitive A-fiber nociceptors, heat-sensitive C-fiber afferents, and cool-sensitive A-fiber afferents. The volar forearm was treated with a high-concentration capsaicin patch for 1 h. Transient heat, warm and cold stimuli designed to activate Aδ- and C-fiber thermonociceptors, C-fiber warm receptors, and Aδ-fiber cold receptors were applied to the skin before and after treatment at days 1, 3, and 7. Reaction times, intensity ratings, and quality descriptors were collected. The stimuli were applied both within the capsaicin-treated skin and around the capsaicin-treated skin to map the changes in thermal sensitivity. We found that topical capsaicin selectively impairs heat sensitivity without any concomitant changes in cold sensitivity. Most interestingly, we observed a differential effect on the sensitivity to thermal inputs conveyed by Aδ- and C-fibers. Reduced sensitivity to Aδ-fiber-mediated heat was restricted to the capsaicin-treated skin, whereas reduced sensitivity to C-fiber-mediated heat extended well beyond the treated skin. Moreover, the time course of the reduced sensitivity to C-fiber-mediated input was more prolonged than the reduced sensitivity to Aδ-fiber-mediated input.
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Affiliation(s)
| | - André Mouraux
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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25
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Uhelski ML, McAdams B, Johns ME, Kabadi RA, Simone DA, Banik RK. Lack of relationship between epidermal denervation by capsaicin and incisional pain behaviours: A laser scanning confocal microscopy study in rats. Eur J Pain 2020; 24:1197-1208. [DOI: 10.1002/ejp.1564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/16/2020] [Accepted: 03/19/2020] [Indexed: 12/21/2022]
Affiliation(s)
- Megan L. Uhelski
- Department of Diagnostic and Biological Sciences School of Dentistry University of Minnesota Minneapolis MN USA
| | - Brian McAdams
- Department of Diagnostic and Biological Sciences School of Dentistry University of Minnesota Minneapolis MN USA
| | - Malcolm E. Johns
- Department of Anesthesiology School of Medicine University of Minnesota Minneapolis MN USA
| | - Rajiv A. Kabadi
- NJ Neuroscience Institute and Seton Hall UniversitySchool of Graduate Medical EducationJFK Medical Center Edison NJ USA
| | - Donald A. Simone
- Department of Diagnostic and Biological Sciences School of Dentistry University of Minnesota Minneapolis MN USA
| | - Ratan K. Banik
- Department of Anesthesiology School of Medicine University of Minnesota Minneapolis MN USA
- NJ Neuroscience Institute and Seton Hall UniversitySchool of Graduate Medical EducationJFK Medical Center Edison NJ USA
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Kant V, Jangir BL, Kumar V, Nigam A, Sharma V. Quercetin accelerated cutaneous wound healing in rats by modulation of different cytokines and growth factors. Growth Factors 2020; 38:105-119. [PMID: 32957814 DOI: 10.1080/08977194.2020.1822830] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Quercetin on wounds could be favorable for healing based on its variety of biological effects. Eighty wounded rats were divided into four groups i.e. dimethyl sulfoxide, 0.03% quercetin, 0.1% quercetin, and 0.3% quercetin-treated. Different treatments were topically applied for 20 days. Quercetin (0.3%) caused the fastest wound closure and markedly improved the oxidative stress. Quercetin treatment increased the expressions of IL-10, VEGF, TGF-β1, CD31, α-SMA, PCNA, and GAP-43, and decreased the expressions of TNF-α. Early infiltration of inflammatory cells and formation of good quality granulation tissue dominated by fibroblast proliferation, angiogenesis, and collagen deposition in quercetin treated groups was also evident. All these effects were more pronounced at 0.3% quercetin concentration. The earliest regeneration of epithelial layer was also observed in 0.3% quercetin-treated wounds. In conclusion, 0.3% quercetin accelerates wound healing efficiently by modulating antioxidant system of wound, cytokines, growth factors, other proteins and cells involved in healing.
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Affiliation(s)
- Vinay Kant
- Department of Veterinary Pharmacology & Toxicology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, India
| | - Babu Lal Jangir
- Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, India
| | - Vinod Kumar
- Department of Veterinary Pharmacology & Toxicology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, India
| | - Ankit Nigam
- Department of Veterinary Pharmacology & Toxicology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, India
| | - Vikash Sharma
- Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary & Animal Sciences (LUVAS), Hisar, India
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The capsaicin receptor TRPV1 is the first line defense protecting from acute non damaging heat: a translational approach. J Transl Med 2020; 18:28. [PMID: 31952468 PMCID: PMC6966804 DOI: 10.1186/s12967-019-02200-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/26/2019] [Indexed: 02/07/2023] Open
Abstract
Background Pain is the vital sense preventing tissue damage by harmful noxious stimuli. The capsaicin receptor TRPV1 is activated by noxious temperatures, however, acute heat pain is only marginally affected in mice after TRPV1 knockout but completely eliminated in mice lacking TRPV1 positive fibers. Exploring contribution of candidate signal transduction mechanisms to heat pain in humans needs translational models. Methods We used focused, non-damaging, short near-infrared laser heat stimuli (wavelength 1470/1475 nm) to study the involvement of TRPV1-expressing nerve fibers in the encoding of heat pain intensity. Human psychophysics (both sexes) were compared to calcium transients in native rat DRG neurons and heterologously expressing HEK293 cells. Results Heating of dermal and epidermal nerve fibers in humans with laser stimuli of ≥ 2.5 mJ (≥ 25 ms, 100 mW) induced pain that increased linearly as a function of stimulus intensity in double logarithmic space across two orders of magnitude and was completely abolished by desensitization using topical capsaicin. In DRG neurons and TRPV1-expressing HEK cells, heat sensitivity was restricted to capsaicin sensitive cells. Strength duration curves (2–10 ms range) and thresholds (DRGs 0.56 mJ, HEK cells 0.52 mJ) were nearly identical. Tachyphylaxis upon repetitive stimulation occurred in HEK cells (54%), DRGs (59%), and humans (25%). Conclusion TRPV1-expressing nociceptors encode transient non-damaging heat pain in humans, thermal gating of TRPV1 is similar in HEK cells and DRG neurons, and TRPV1 tachyphylaxis is an important modulator of heat pain sensitivity. These findings suggest that TRPV1 expressed in dermal and epidermal populations of nociceptors serves as first line defense against heat injury.
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28
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Anand P, Elsafa E, Privitera R, Naidoo K, Yiangou Y, Donatien P, Gabra H, Wasan H, Kenny L, Rahemtulla A, Misra P. Rational treatment of chemotherapy-induced peripheral neuropathy with capsaicin 8% patch: from pain relief towards disease modification. J Pain Res 2019; 12:2039-2052. [PMID: 31308732 PMCID: PMC6613356 DOI: 10.2147/jpr.s213912] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/13/2019] [Indexed: 12/30/2022] Open
Abstract
Purpose Chemotherapy-induced peripheral neuropathy (CIPN) with associated chronic pain is a common and disabling condition. Current treatments for neuropathic pain in CIPN are largely ineffective, with unfavorable side-effects. The capsaicin 8% patch (capsaicin 179 mg patch) is approved for the treatment of neuropathic pain: a single topical cutaneous application can produce effective pain relief for up to 12 weeks. We assessed the therapeutic potential of capsaicin 8% patch in patients with painful CIPN, and its mechanism of action. Patients and methods 16 patients with chronic painful CIPN (mean duration 2.5 years), in remission for cancer and not receiving chemotherapy, were treated with 30 min application of capsaicin 8% patch to the feet. Symptoms were monitored using the 11-point numerical pain rating scale (NPRS), and questionnaires. Investigations were performed at baseline and three months after patch application, including skin biopsies with a range of markers, and quantitative sensory testing (QST). Results Patients reported significant reduction in spontaneous pain (mean NPRS: −1.27; 95% CI 0.2409 to 2.301; p=0.02), touch-evoked pain (−1.823; p=0.03) and cold-evoked pain (−1.456; p=0.03). Short-Form McGill questionnaire showed a reduction in neuropathic (p=0.0007), continuous (p=0.01) and overall pain (p=0.004); Patient Global Impression of Change showed improvement (p=0.001). Baseline skin biopsies showed loss of intra-epidermal nerve fibers (IENF), and also of sub-epidermal nerve fibers quantified by image analysis. Post-patch application skin biopsies showed a significant increase towards normalization of intra-epidermal and sub-epidermal nerve fibers (for IENF: structural marker PGP9.5, p=0.009; heat receptor TRPV1, p=0.027; regenerating nerve marker GAP43, p=0.04). Epidermal levels of Nerve Growth Factor (NGF), Neurotrophin-3 (NT-3), and Langerhans cells were also normalized. QST remained unchanged and there were no systemic side-effects, as in previous studies. Conclusion Capsaicin 8% patch provides significant pain relief in CIPN, and may lead to regeneration and restoration of sensory nerve fibers ie, disease modification.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Amin Rahemtulla
- Hematology, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
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29
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Bönhof GJ, Herder C, Strom A, Papanas N, Roden M, Ziegler D. Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy. Endocr Rev 2019; 40:153-192. [PMID: 30256929 DOI: 10.1210/er.2018-00107] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/23/2018] [Indexed: 12/12/2022]
Abstract
Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.
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Affiliation(s)
- Gidon J Bönhof
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Christian Herder
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research, Munich-Neuherberg, Neuherberg, Partner Düsseldorf, Düsseldorf, Germany.,Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Alexander Strom
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research, Munich-Neuherberg, Neuherberg, Partner Düsseldorf, Düsseldorf, Germany
| | - Nikolaos Papanas
- Second Department of Internal Medicine, Diabetes Center, Diabetic Foot Clinic, Democritus University of Thrace, Alexandroupolis, Greece
| | - Michael Roden
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research, Munich-Neuherberg, Neuherberg, Partner Düsseldorf, Düsseldorf, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Dan Ziegler
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research, Munich-Neuherberg, Neuherberg, Partner Düsseldorf, Düsseldorf, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
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30
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Sopacua M, Hoeijmakers JGJ, Merkies ISJ, Lauria G, Waxman SG, Faber CG. Small‐fiber neuropathy: Expanding the clinical pain universe. J Peripher Nerv Syst 2019; 24:19-33. [DOI: 10.1111/jns.12298] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/27/2018] [Accepted: 12/14/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Maurice Sopacua
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
| | - Janneke G. J. Hoeijmakers
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
| | - Ingemar S. J. Merkies
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
- Department of NeurologySt. Elisabeth Hospital Willemstad Curaçao
| | - Giuseppe Lauria
- Neuroalgology UnitIRCCS Foundation, “Carlo Besta” Neurological Institute Milan Italy
- Department of Biomedical and Clinical Sciences “Luigi Sacco”University of Milan Milan Italy
| | - Stephen G. Waxman
- Department of NeurologyYale University School of Medicine New Haven Connecticut
- Center for Neuroscience and Regeneration ResearchVA Connecticut Healthcare System West Haven Connecticut
| | - Catharina G. Faber
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
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31
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Abstract
Clinical neurophysiologic investigation of pain pathways in humans is based on specific techniques and approaches, since conventional methods of nerve conduction studies and somatosensory evoked potentials do not explore these pathways. The proposed techniques use various types of painful stimuli (thermal, laser, mechanical, or electrical) and various types of assessments (measurement of sensory thresholds, study of nerve fiber excitability, or recording of electromyographic reflexes or cortical potentials). The two main tests used in clinical practice are quantitative sensory testing and pain-related evoked potentials (PREPs). In particular, PREPs offer the possibility of an objective assessment of nociceptive pathways. Three types of PREPs can be distinguished depending on the type of stimulation used to evoke pain: laser-evoked potentials, contact heat evoked potentials, and intraepidermal electrical stimulation evoked potentials (IEEPs). These three techniques investigate both small-diameter peripheral nociceptive afferents (mainly Aδ nerve fibers) and spinothalamic tracts without theoretically being able to differentiate the level of lesion in the case of abnormal results. In routine clinical practice, PREP recording is a reliable method of investigation for objectifying the existence of a peripheral or central lesion or loss of function concerning the nociceptive pathways, but not the existence of pain. Other methods, such as nerve fiber excitability studies using microneurography, more directly reflect the activities of nociceptive axons in response to provoked pain, but without detecting or quantifying the presence of spontaneous pain. These methods are more often used in research or experimental study design. Thus, it should be kept in mind that most of the results of neurophysiologic investigation performed in clinical practice assess small fiber or spinothalamic tract lesions rather than the neuronal mechanisms directly at the origin of pain and they do not provide objective quantification of pain.
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Affiliation(s)
- Jean-Pascal Lefaucheur
- Excitabilité Nerveuse et Thérapeutique, Faculté de Médecine de Créteil, Université Paris-Est-Créteil, Hôpital Henri Mondor, Créteil, France; Service de Physiologie-Explorations Fonctionnelles, Hôpital Henri Mondor, Créteil, France.
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32
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Chiang H, Chang KC, Kan HW, Wu SW, Tseng MT, Hsueh HW, Lin YH, Chao CC, Hsieh ST. Physiological and pathological characterization of capsaicin-induced reversible nerve degeneration and hyperalgesia. Eur J Pain 2018; 22:1043-1056. [DOI: 10.1002/ejp.1189] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2017] [Indexed: 11/07/2022]
Affiliation(s)
- H. Chiang
- Department of Anatomy and Cell Biology; National Taiwan University College of Medicine; Taipei Taiwan
| | - K.-C. Chang
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
| | - H.-W. Kan
- Department of Anatomy and Cell Biology; National Taiwan University College of Medicine; Taipei Taiwan
| | - S.-W. Wu
- Department of Anatomy and Cell Biology; National Taiwan University College of Medicine; Taipei Taiwan
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
| | - M.-T. Tseng
- Graduate Institute of Brain and Mind Sciences; National Taiwan University College of Medicine; Taipei Taiwan
| | - H.-W. Hsueh
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
| | - Y.-H. Lin
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
| | - C.-C. Chao
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
| | - S.-T. Hsieh
- Department of Anatomy and Cell Biology; National Taiwan University College of Medicine; Taipei Taiwan
- Department of Neurology; National Taiwan University Hospital; Taipei Taiwan
- Graduate Institute of Brain and Mind Sciences; National Taiwan University College of Medicine; Taipei Taiwan
- Graduate Institute of Clinical Medicine; National Taiwan University College of Medicine; Taipei Taiwan
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33
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Bönhof GJ, Strom A, Püttgen S, Ringel B, Brüggemann J, Bódis K, Müssig K, Szendroedi J, Roden M, Ziegler D. Patterns of cutaneous nerve fibre loss and regeneration in type 2 diabetes with painful and painless polyneuropathy. Diabetologia 2017; 60:2495-2503. [PMID: 28914336 DOI: 10.1007/s00125-017-4438-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/02/2017] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS The determinants and mechanisms of the development of diabetic sensorimotor polyneuropathy as a painful (DSPN+p) or painless (DSPN-p) entity remain unclear. We examined the degree of cutaneous nerve fibre loss and regeneration in individuals with type 2 diabetes with DSPN+p or DSPN-p compared with individuals with recent-onset type 2 diabetes and corresponding healthy volunteers. METHODS In this cross-sectional study, skin biopsies taken from the distal lateral calf were obtained from individuals with recent-onset type 2 diabetes (n = 32) from the German Diabetes Study, with DSPN+p (n = 34) and DSPN-p (n = 32) from the PROPANE study, and volunteers with normal glucose tolerance (n = 50). Double immunofluorescence staining for protein gene product 9.5 (PGP9.5) (pan-neuronal marker) and growth-associated protein 43 (GAP-43) (nerve regeneration marker) was applied to assess intraepidermal nerve fibre density (IENFD) and length (IENFL) and dermal nerve fibre length (DNFL). DSPN was diagnosed using the modified Toronto Consensus (2011) criteria, while neuropathic pain was assessed using an 11-point Numerical Rating Scale. RESULTS After adjustment for age, sex, BMI and HbA1c, IENFD and IENFL were reduced for both markers in individuals with recent-onset diabetes and both DSPN groups compared with control participants (all p < 0.05), but did not differ between the DSPN groups. The DNFL GAP-43/PGP9.5 ratio was higher in the DSPN+p and DSPN-p groups compared with control participants (1.18 ± 0.28 and 1.07 ± 0.10 vs 1.02 ± 0.10; p ≤ 0.05) and in the DSPN + p group compared with DSPN-p (p < 0.05). Correlation analyses showed distinct inverse associations between the DNFL GAP-43/PGP9.5 ratio and PGP9.5 positive IENFD as well as DNFL (IENFD: β = -0.569, DNFL: β = -0.639; both p < 0.0001) in individuals with type 2 diabetes, but not in the control group. A similar pattern was found for correlations between the DNFL GAP-43/PGP9.5 ratio and peripheral nerve function tests. CONCLUSIONS/INTERPRETATION Dermal nerve fibre regeneration is enhanced in DSPN, particularly in DSPN+p, and increases with advancing intraepidermal nerve fibre loss. These data suggest that, despite progressive epidermal fibre loss, dermal nerve repair is preserved, particularly in DSPN+p, but fails to adequately counteract epidermal neurodegenerative processes.
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Affiliation(s)
- Gidon J Bönhof
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Alexander Strom
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, Neuherberg, Germany
| | - Sonja Püttgen
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Bernd Ringel
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Jutta Brüggemann
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Kálmán Bódis
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
| | - Karsten Müssig
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, Neuherberg, Germany
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Julia Szendroedi
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, Neuherberg, Germany
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Michael Roden
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, Neuherberg, Germany
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Dan Ziegler
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Auf'm Hennekamp 65, 40225, Düsseldorf, Germany.
- German Center for Diabetes Research (DZD), Munich, Neuherberg, Germany.
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany.
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Anand P, Privitera R, Yiangou Y, Donatien P, Birch R, Misra P. Trench Foot or Non-Freezing Cold Injury As a Painful Vaso-Neuropathy: Clinical and Skin Biopsy Assessments. Front Neurol 2017; 8:514. [PMID: 28993756 PMCID: PMC5626869 DOI: 10.3389/fneur.2017.00514] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/13/2017] [Indexed: 01/05/2023] Open
Abstract
Background Trench foot, or non-freezing cold injury (NFCI), results from cold exposure of sufficient severity and duration above freezing point, with consequent sensory and vascular abnormalities which may persist for years. Based on observations of Trench foot in World War II, the condition was described as a vaso-neuropathy. While some reports have documented nerve damage after extreme cold exposure, sensory nerve fibres and vasculature have not been assessed with recent techniques in NFCI. Objective To assess patients with chronic sensory symptoms following cold exposure, in order to diagnose any underlying small fibre neuropathy, and provide insight into mechanisms of the persistent pain and cold hypersensitivity. Methods Thirty soldiers with cold exposure and persistent sensory symptoms (>4 months) were assessed with quantitative sensory testing, nerve conduction studies, and skin biopsies. Immunohistochemistry was used to assess intraepidermal (IENF) and subepidermal (SENF) nerve fibres with a range of markers, including the pan-neuronal marker protein gene product 9.5 (PGP 9.5), regenerating fibres with growth-associated protein 43 (GAP43), and nociceptor fibres with transient receptor potential cation channel subfamily V member 1 (TRPV1), sensory neuron-specific receptor (SNSR), and calcitonin gene-related peptide (CGRP). von Willebrand factor (vWF), endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor (VEGF) were used for assessing blood vessels, and transient receptor potential cation channel, subfamily A member 1 (TRPA1) and P2X purinoceptor 7 (P2X7) for keratinocytes, which regulate nociceptors via release of nerve growth factor. Results Clinical examination showed pinprick sensation was abnormal in the feet of 20 patients (67%), and between 67 and 83% had abnormalities of thermal thresholds to the different modalities. 7 patients (23%) showed reduced sensory action potential amplitude of plantar nerves. 27 patients (90%) had decreased calf skin PGP 9.5 IENF (p < 0.0001), the remaining 3 patients had decreased nerve markers in subepidermis or foot skin. There were marked increases of all vascular markers (for vWF in calf skin, p < 0.0001), and increased sensory or regenerating SENF (for calf skin, GAP43, p = 0.002). TRPA1 (p = 0.0012) and P2X7 (p < 0.0001) were increased in basal keratinocytes. Conclusion A range of skin biopsy markers and plantar nerve conduction studies are useful objective assessments for the diagnosis of peripheral neuropathy in NFCI. Our results suggest that an increase in blood vessels following tissue ischaemia/hypoxia could be associated with disproportionate and abnormal nerve fibres (irritable nociceptors), and may lead to NFCI as a “painful vaso-neuropathy.”
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Affiliation(s)
- Praveen Anand
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
| | - Rosario Privitera
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
| | - Yiangos Yiangou
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
| | - Philippe Donatien
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
| | - Rolfe Birch
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
| | - Peter Misra
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College, London, United Kingdom
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Quantitative sensory testing and structural assessment of sensory nerve fibres in amyotrophic lateral sclerosis. J Neurol Sci 2017; 373:329-334. [DOI: 10.1016/j.jns.2017.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/12/2016] [Accepted: 01/03/2017] [Indexed: 11/22/2022]
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Usefulness of laser-evoked potentials and quantitative sensory testing in the diagnosis of neuropathic spinal cord injury pain: a multiple case study. Spinal Cord 2017; 55:575-582. [PMID: 28117333 DOI: 10.1038/sc.2016.191] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 12/12/2016] [Accepted: 12/18/2016] [Indexed: 12/18/2022]
Abstract
STUDY DESIGN A retrospective study. OBJECTIVES The aim of this study was to investigate the contribution of laser-evoked potentials (LEPs) and quantitative sensory testing (QST) to the diagnosis of neuropathic pain in patients with spinal cord injury (SCI) and inconclusive magnetic resonance imaging (MRI) findings. SETTING A multidisciplinary pain center. METHODS QST (DFNS protocol) and Tm-YAG-laser stimulation of the skin were applied within the pain site corresponding with dermatomes of altered sensation. Available MRI scans were reviewed. RESULTS Thirteen individuals (50±16 years) with SCI were examined. In four cases with no detectable neural lesion on MRI, all QST but three LEP were abnormal. In four patients with poorly defined spinal lesion on MRI, all QST but three LEP only were abnormal. In four cases where pain was not matching adequately with MRI lesions, all patients had abnormal LEP and QST. In one patient showing a spinal cord atrophy, LEP was normal but QST was abnormal. Findings supported the diagnoses at-level (n=5) and below-level (n=8) SCI pain. Spinothalamic tract function assessed by LEP was normal in three cases, but QST was abnormal in all cases. CONCLUSIONS As QST is a psychophysical examination depending on patient cooperation, we suggest that the combination of QST and LEP might be a valuable diagnostic tool to detect lesions of the somatosensory system in a subgroup of patients with neuropathic spinal cord injury pain and inconclusive MRI findings.
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Chung MK, Campbell JN. Use of Capsaicin to Treat Pain: Mechanistic and Therapeutic Considerations. Pharmaceuticals (Basel) 2016; 9:ph9040066. [PMID: 27809268 PMCID: PMC5198041 DOI: 10.3390/ph9040066] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 12/31/2022] Open
Abstract
Capsaicin is the pungent ingredient of chili peppers and is approved as a topical treatment of neuropathic pain. The analgesia lasts for several months after a single treatment. Capsaicin selectively activates TRPV1, a Ca2+-permeable cationic ion channel that is enriched in the terminals of certain nociceptors. Activation is followed by a prolonged decreased response to noxious stimuli. Interest also exists in the use of injectable capsaicin as a treatment for focal pain conditions, such as arthritis and other musculoskeletal conditions. Recently injection of capsaicin showed therapeutic efficacy in patients with Morton’s neuroma, a painful foot condition associated with compression of one of the digital nerves. The relief of pain was associated with no change in tactile sensibility. Though injection evokes short term pain, the brief systemic exposure and potential to establish long term analgesia without other sensory changes creates an attractive clinical profile. Short-term and long-term effects arise from both functional and structural changes in nociceptive terminals. In this review, we discuss how local administration of capsaicin may induce ablation of nociceptive terminals and the clinical implications.
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Affiliation(s)
- Man-Kyo Chung
- Department of Neural and Pain Sciences, University of Maryland, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, Baltimore, MD 21201, USA.
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How diagnostic tests help to disentangle the mechanisms underlying neuropathic pain symptoms in painful neuropathies. Pain 2016; 157 Suppl 1:S53-S59. [PMID: 26785156 DOI: 10.1097/j.pain.0000000000000367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Neuropathic pain, ie, pain arising directly from a lesion or disease affecting the somatosensory afferent pathway, manifests with various symptoms, the commonest being ongoing burning pain, electrical shock-like sensations, and dynamic mechanical allodynia. Reliable insights into the mechanisms underlying neuropathic pain symptoms come from diagnostic tests documenting and quantifying somatosensory afferent pathway damage in patients with painful neuropathies. Neurophysiological investigation and skin biopsy studies suggest that ongoing burning pain primarily reflects spontaneous activity in nociceptive-fiber pathways. Electrical shock-like sensations presumably arise from high-frequency ectopic bursts generated in demyelinated, nonnociceptive, Aβ fibers. Although the mechanisms underlying dynamic mechanical allodynia remain debatable, normally innocuous stimuli might cause pain by activating spared and sensitized nociceptive afferents. Extending the mechanistic approach to neuropathic pain symptoms might advance targeted therapy for the individual patient and improve testing for new drugs.
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Van Acker N, Ragé M, Vermeirsch H, Schrijvers D, Nuydens R, Byttebier G, Timmers M, De Schepper S, Streffer J, Andries L, Plaghki L, Cras P, Meert T. NRP-1 Receptor Expression Mismatch in Skin of Subjects with Experimental and Diabetic Small Fiber Neuropathy. PLoS One 2016; 11:e0161441. [PMID: 27598321 PMCID: PMC5012683 DOI: 10.1371/journal.pone.0161441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/07/2016] [Indexed: 12/27/2022] Open
Abstract
The in vivo cutaneous nerve regeneration model using capsaicin is applied extensively to study the regenerative mechanisms and therapeutic efficacy of disease modifying molecules for small fiber neuropathy (SFN). Since mismatches between functional and morphological nerve fiber recovery are described for this model, we aimed at determining the capability of the capsaicin model to truly mimic the morphological manifestations of SFN in diabetes. As nerve and blood vessel growth and regenerative capacities are defective in diabetes, we focused on studying the key regulator of these processes, the neuropilin-1 (NRP-1)/semaphorin pathway. This led us to the evaluation of NRP-1 receptor expression in epidermis and dermis of subjects presenting experimentally induced small fiber neuropathy, diabetic polyneuropathy and of diabetic subjects without clinical signs of small fiber neuropathy. The NRP-1 receptor was co-stained with CD31 vessel-marker using immunofluorescence and analyzed with Definiens® technology. This study indicates that capsaicin application results in significant loss of epidermal NRP-1 receptor expression, whereas diabetic subjects presenting small fiber neuropathy show full epidermal NRP-1 expression in contrast to the basal expression pattern seen in healthy controls. Capsaicin induced a decrease in dermal non-vascular NRP-1 receptor expression which did not appear in diabetic polyneuropathy. We can conclude that the capsaicin model does not mimic diabetic neuropathy related changes for cutaneous NRP-1 receptor expression. In addition, our data suggest that NRP-1 might play an important role in epidermal nerve fiber loss and/or defective regeneration and that NRP-1 receptor could change the epidermal environment to a nerve fiber repellant bed possibly through Sem3A in diabetes.
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Affiliation(s)
- Nathalie Van Acker
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- HistoGeneX NV, Antwerp, Belgium
- * E-mail:
| | - Michael Ragé
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | | | | | - Rony Nuydens
- Janssen Research and Development, Janssen Pharmaceutics NV, Beerse, Belgium
| | - Geert Byttebier
- Janssen Research and Development, Janssen Pharmaceutics NV, Beerse, Belgium
| | - Maarten Timmers
- Janssen Research and Development, Janssen Pharmaceutics NV, Beerse, Belgium
- Reference Center for Biological Markers of Dementia (BIODEM), Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | | | - Johannes Streffer
- Janssen Research and Development, Janssen Pharmaceutics NV, Beerse, Belgium
- Reference Center for Biological Markers of Dementia (BIODEM), Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | | | - Léon Plaghki
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Patrick Cras
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- Department of Neurology, Antwerp University Hospital, Born Bunge Institute, University of Antwerp, Antwerp, Belgium
| | - Theo Meert
- Janssen Research and Development, Janssen Pharmaceutics NV, Beerse, Belgium
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Van Acker N, Ragé M, Sluydts E, Knaapen MWM, De Bie M, Timmers M, Fransen E, Duymelinck C, De Schepper S, Anand P, Meert T, Plaghki L, Cras P. Automated PGP9.5 immunofluorescence staining: a valuable tool in the assessment of small fiber neuropathy? BMC Res Notes 2016; 9:280. [PMID: 27215701 PMCID: PMC4878004 DOI: 10.1186/s13104-016-2085-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 05/11/2016] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND In this study we explored the possibility of automating the PGP9.5 immunofluorescence staining assay for the diagnosis of small fiber neuropathy using skin punch biopsies. The laboratory developed test (LDT) was subjected to a validation strategy as required by good laboratory practice guidelines and compared to the well-established gold standard method approved by the European Federation of Neurological Societies (EFNS). To facilitate automation, the use of thinner sections. (16 µm) was evaluated. Biopsies from previously published studies were used. The aim was to evaluate the diagnostic performance of the LDT compared to the gold standard. We focused on technical aspects to reach high-quality standardization of the PGP9.5 assay and finally evaluate its potential for use in large scale batch testing. RESULTS We first studied linear nerve fiber densities in skin of healthy volunteers to establish reference ranges, and compared our LDT using the modifications to the EFNS counting rule to the gold standard in visualizing and quantifying the epidermal nerve fiber network. As the LDT requires the use of 16 µm tissue sections, a higher incidence of intra-epidermal nerve fiber fragments and a lower incidence of secondary branches were detected. Nevertheless, the LDT showed excellent concordance with the gold standard method. Next, the diagnostic performance and yield of the LDT were explored and challenged to the gold standard using skin punch biopsies of capsaicin treated subjects, and patients with diabetic polyneuropathy. The LDT reached good agreement with the gold standard in identifying small fiber neuropathy. The reduction of section thickness from 50 to 16 µm resulted in a significantly lower visualization of the three-dimensional epidermal nerve fiber network, as expected. However, the diagnostic performance of the LDT was adequate as characterized by a sensitivity and specificity of 80 and 64 %, respectively. CONCLUSIONS This study, designed as a proof of principle, indicated that the LDT is an accurate, robust and automated assay, which adequately and reliably identifies patients presenting with small fiber neuropathy, and therefore has potential for use in large scale clinical studies.
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Affiliation(s)
- Nathalie Van Acker
- />Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- />HistoGeneX NV, Pr J Charlottelaan 10, Berchem, 2600 Antwerp, Belgium
| | - Michael Ragé
- />Institute of Neuroscience, Université Catholique de Louvain, Avenue Mounier 53, B1.53.04, 1200 Brussels, Belgium
| | - Ellen Sluydts
- />HistoGeneX NV, Pr J Charlottelaan 10, Berchem, 2600 Antwerp, Belgium
| | | | - Martine De Bie
- />HistoGeneX NV, Pr J Charlottelaan 10, Berchem, 2600 Antwerp, Belgium
| | - Maarten Timmers
- />Janssen Research and Development, Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium
- />Reference Center for Biological Markers of Dementia (BIODEM), Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Erik Fransen
- />StatUa Center for Statistics, University of Antwerp, Antwerp, Belgium
| | - Carla Duymelinck
- />HistoGeneX NV, Pr J Charlottelaan 10, Berchem, 2600 Antwerp, Belgium
| | | | - Praveen Anand
- />Peripheral Neuropathy Unit, Hammersmith Hospital, Du Cane Road, London, W12 0HS UK
| | - Theo Meert
- />Janssen Research and Development, Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium
| | - Léon Plaghki
- />Institute of Neuroscience, Université Catholique de Louvain, Avenue Mounier 53, B1.53.04, 1200 Brussels, Belgium
| | - Patrick Cras
- />Department of Neurology, Antwerp University Hospital, Born Bunge Institute, University of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium
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Responsiveness of electrical nociceptive detection thresholds to capsaicin (8 %)-induced changes in nociceptive processing. Exp Brain Res 2016; 234:2505-14. [PMID: 27142052 PMCID: PMC4978767 DOI: 10.1007/s00221-016-4655-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 04/15/2016] [Indexed: 12/25/2022]
Abstract
Pain disorders can be initiated and maintained by malfunctioning of one or several mechanisms underlying the nociceptive function. Psychophysical procedures allow the estimation of nociceptive detection thresholds using intra-epidermal electrical stimuli. By varying the temporal properties of electrical stimuli, various contributions of nociceptive processes to stimulus processing can be observed. To observe the responsiveness of nociceptive thresholds to changes in nociceptive function, a model of capsaicin-induced nerve defunctionalization was used. Its effect on nociceptive detections thresholds was investigated over a period of 84 days. A cutaneous capsaicin (8 %) patch was applied for 60 min to the upper leg of eight healthy human participants. Single- and double-pulse electrical stimuli were presented in a pseudo-random order using an intra-epidermal electrode. Stimuli and corresponding responses were recorded on both treated and untreated skin areas prior to capsaicin application and on days 2, 7, 28, and 84. Increases in electrical detection thresholds at the capsaicin area were observed on days 2 and 7 for single-pulse stimuli. Detection thresholds corresponding to double-pulse stimuli were increased on days 7 and 28, suggesting a delayed and longer lasting effect on double-pulse stimuli. In the present study, it was demonstrated that the responsiveness of detection thresholds to capsaicin application depends on the temporal properties of electrical stimuli. The observation of capsaicin-induced changes by estimation of detection thresholds revealed different time patterns of contributions of peripheral and central mechanisms to stimulus processing.
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Landmann G, Lustenberger C, Schleinzer W, Schmelz M, Stockinger L, Rukwied R. Short lasting transient effects of a capsaicin 8% patch on nociceptor activation in humans. Eur J Pain 2016; 20:1443-53. [DOI: 10.1002/ejp.867] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2016] [Indexed: 11/08/2022]
Affiliation(s)
- G. Landmann
- Centre for Pain Medicine; Swiss Paraplegic Centre; Nottwil Switzerland
| | - C. Lustenberger
- Centre for Pain Medicine; Swiss Paraplegic Centre; Nottwil Switzerland
| | - W. Schleinzer
- Centre for Pain Medicine; Swiss Paraplegic Centre; Nottwil Switzerland
| | - M. Schmelz
- University Medicine Mannheim; Department of Anesthesiology and Intensive Care Medicine; University of Heidelberg; Germany
| | - L. Stockinger
- Centre for Pain Medicine; Swiss Paraplegic Centre; Nottwil Switzerland
| | - R. Rukwied
- University Medicine Mannheim; Department of Anesthesiology and Intensive Care Medicine; University of Heidelberg; Germany
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Henrich F, Magerl W, Klein T, Greffrath W, Treede RD. Capsaicin-sensitive C- and A-fibre nociceptors control long-term potentiation-like pain amplification in humans. Brain 2015; 138:2505-20. [DOI: 10.1093/brain/awv108] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 02/24/2015] [Indexed: 01/08/2023] Open
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Kant V, Kumar D, Kumar D, Prasad R, Gopal A, Pathak NN, Kumar P, Tandan SK. Topical application of substance P promotes wound healing in streptozotocin-induced diabetic rats. Cytokine 2015; 73:144-55. [DOI: 10.1016/j.cyto.2014.12.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 12/11/2022]
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Cheung A, Podgorny P, Martinez JA, Chan C, Toth C. Epidermal axonal swellings in painful and painless diabetic peripheral neuropathy. Muscle Nerve 2015; 51:505-13. [DOI: 10.1002/mus.24351] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Audrey Cheung
- Department of Clinical Neurosciences; HMRB 155; Foothills Hospital; University of Calgary, Hotchkiss Brain Institute; 3330 Hospital Drive NW Calgary Alberta T2N 4N1 Canada
| | - Peter Podgorny
- Department of Clinical Neurosciences; HMRB 155; Foothills Hospital; University of Calgary, Hotchkiss Brain Institute; 3330 Hospital Drive NW Calgary Alberta T2N 4N1 Canada
| | - Jose A. Martinez
- Department of Clinical Neurosciences; HMRB 155; Foothills Hospital; University of Calgary, Hotchkiss Brain Institute; 3330 Hospital Drive NW Calgary Alberta T2N 4N1 Canada
| | - Cynthia Chan
- Department of Clinical Neurosciences; HMRB 155; Foothills Hospital; University of Calgary, Hotchkiss Brain Institute; 3330 Hospital Drive NW Calgary Alberta T2N 4N1 Canada
| | - Cory Toth
- Department of Clinical Neurosciences; HMRB 155; Foothills Hospital; University of Calgary, Hotchkiss Brain Institute; 3330 Hospital Drive NW Calgary Alberta T2N 4N1 Canada
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Bischoff JM, Ringsted TK, Petersen M, Sommer C, Üçeyler N, Werner MU. A capsaicin (8%) patch in the treatment of severe persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled trial. PLoS One 2014; 9:e109144. [PMID: 25290151 PMCID: PMC4188585 DOI: 10.1371/journal.pone.0109144] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 09/02/2014] [Indexed: 11/25/2022] Open
Abstract
Background Persistent pain after inguinal herniorrhaphy is a disabling condition with a lack of evidence-based pharmacological treatment options. This randomized placebo-controlled trial investigated the efficacy of a capsaicin 8% cutaneous patch in the treatment of severe persistent inguinal postherniorrhaphy pain. Methods Forty-six patients with persistent inguinal postherniorrhaphy pain were randomized to receive either a capsaicin 8% patch or a placebo patch. Pain intensity (Numerical Rating Scale [NRS 0–10]) was evaluated under standardized conditions (at rest, during movement, and during pressure) at baseline and at 1, 2 and 3 months after patch application. Skin punch biopsies for intraepidermal nerve fiber density (IENFD) measurements were taken at baseline and 1 month after patch application. Quantitative sensory testing was performed at baseline and at 1, 2, and 3 months after patch application. The primary outcome was comparisons of summed pain intensity differences (SPIDs) between capsaicin and placebo treatments at 1, 2 and 3 months after patch application (significance level P<0.01). Results The maximum difference in SPID, between capsaicin and placebo treatments, was observed at 1 month after patch application, but the pain reduction was not significant (NRS, mean difference [95% CI]: 5.0 [0.09 to 9.9]; P = 0.046). No differences in SPID between treatments were observed at 2 and 3 months after patch application. Changes in IENFD on the pain side, from baseline to 1 month after patch application, did not differ between capsaicin and placebo treatment: 1.9 [−0.1 to 3.9] and 0.6 [−1.2 to 2.5] fibers/mm, respectively (P = 0.32). No significant changes in sensory function, sleep quality or psychological factors were associated with capsaicin patch treatment. Conclusions The study did not demonstrate significant differences in pain relief between capsaicin and placebo treatment, although a trend toward pain improvement in capsaicin treated patients was observed 1 month after patch application. Trial Registration Clinicaltrialsregister.eu 2012-001540-22 ClinicalTrials.gov NCT01699854
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Affiliation(s)
- Joakim M. Bischoff
- Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark
- * E-mail:
| | - Thomas K. Ringsted
- Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark
| | - Marian Petersen
- Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark
| | - Claudia Sommer
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
| | - Nurcan Üçeyler
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
| | - Mads U. Werner
- Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark
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Kodaira M, Inui K, Kakigi R. Evaluation of nociceptive Aδ- and C-fiber dysfunction with lidocaine using intraepidermal electrical stimulation. Clin Neurophysiol 2014; 125:1870-7. [DOI: 10.1016/j.clinph.2014.01.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/16/2014] [Accepted: 01/18/2014] [Indexed: 10/25/2022]
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Truini A, Biasiotta A, Di Stefano G, Leone C, La Cesa S, Galosi E, Piroso S, Pepe A, Giordano C, Cruccu G. Does the epidermal nerve fibre density measured by skin biopsy in patients with peripheral neuropathies correlate with neuropathic pain? Pain 2014; 155:828-832. [DOI: 10.1016/j.pain.2014.01.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/23/2014] [Accepted: 01/27/2014] [Indexed: 01/15/2023]
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Madsen CS, Finnerup NB, Baumgärtner U. Assessment of small fibers using evoked potentials. Scand J Pain 2014; 5:111-118. [DOI: 10.1016/j.sjpain.2013.11.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 11/16/2013] [Indexed: 01/08/2023]
Abstract
Abstract
Background and purpose
Conventional neurophysiological techniques do not assess the function of nociceptive pathways and are inadequate to detect abnormalities in patients with small-fiber damage. This overview aims to give an update on the methods and techniques used to assess small fiber (Aδ- and C-fibers) function using evoked potentials in research and clinical settings.
Methods
Noxious radiant or contact heat allows the recording of heat-evoked brain potentials commonly referred to as laser evoked potentials (LEPs) and contact heat-evoked potentials (CHEPs). Both methods reliably assess the loss of Aδ-fiber function by means of reduced amplitude and increased latency of late responses, whereas other methods have been developed to record ultra-late C-fiber-related potentials. Methodological considerations with the use of LEPs and CHEPs include fixed versus variable stimulation site, application pressure, and attentional factors. While the amplitude of LEPs and CHEPs often correlates with the reported intensity of the stimulation, these factors may also be dissociated. It is suggested that the magnitude of the response may be related to the saliency of the noxious stimulus (the ability of the stimulus to stand out from the background) rather than the pain perception.
Results
LEPs and CHEPs are increasingly used as objective laboratory tests to assess the pathways mediating thermal pain, but new methods have recently been developed to evaluate other small-fiber pathways. Pain-related electrically evoked potentials with a low-intensity electrical simulation have been proposed as an alternative method to selectively activate Aδ-nociceptors. A new technique using a flat tip mechanical stimulator has been shown to elicit brain potentials following activation of Type I A mechano-heat (AMH) fibers. These pinprick-evoked potentials (PEP) have a morphology resembling those of heat-evoked potentials following activation of Type II AMH fibers, but with a shorter latency. Cool-evoked potentials can be used for recording the non-nociceptive pathways for cooling. At present, the use of cool-evoked potentials is still in the experimental state. Contact thermodes designed to generate steep heat ramps may be programmed differently to generate cool ramps from a baseline of 35◦C down to 32◦C or 30◦C. Small-fiber evoked potentials are valuable tools for assessment of small-fiber function in sensory neuropathy, central nervous system lesion, and for the diagnosis of neuropathic pain. Recent studies suggest that both CHEPs and pinprick-evoked potentials may also be convenient tools to assess sensitization of the nociceptive system.
Conclusions
In future studies, small-fiber evoked potentials may also be used in studies that aim to understand pain mechanisms including different neuropathic pain phenotypes, such as cold- or touch-evoked allodynia, and to identify predictors of response to pharmacological pain treatment.
Implications
Future studies are needed for some of the newly developed methods.
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Affiliation(s)
- Caspar Skau Madsen
- Danish Pain Research Center , Aarhus University Hospital , Aarhus , Denmark
| | | | - Ulf Baumgärtner
- Department of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM) , Heidelberg University , Mannheim , Germany
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Registre observationnel de l’efficacité et de la tolérance de la capsaïcine 8 % (Qutenza®) dans les douleurs neuropathiques périphériques localisées pharmacorésistantes. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11724-014-0367-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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