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Matthiesen ST, Sieg M, Andersen SS, Amanzio M, Finnerup NB, Jensen TS, Gottrup H, Vase L. Placebo analgesia and nocebo hyperalgesia in patients with Alzheimer disease and healthy participants. Pain 2024; 165:440-449. [PMID: 37703397 DOI: 10.1097/j.pain.0000000000003035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 05/23/2023] [Indexed: 09/15/2023]
Abstract
ABSTRACT The role of placebo analgesia and nocebo hyperalgesia in patients with Alzheimer disease (AD) is largely unknown, with only few studies in the area. Therefore, this study aims to investigate to which extent placebo analgesia and nocebo hyperalgesia effects are present in patients experiencing mild-to-moderate AD. Twenty-one patients with AD (test population) and 26 healthy participants (HP; design validation) were exposed to thermal pain stimulation on 3 test days: Lidocaine condition (open/hidden lidocaine administration), capsaicin condition (open/hidden capsaicin administration), and natural history (no treatment), in a randomized, within-subject design. Open lidocaine and open capsaicin were accompanied by verbal suggestions for pain relief and pain increase, respectively. Expected pain and actual pain intensity were measured on a numerical rating scale (0-10). Placebo and nocebo effects were calculated as pain differences in open-hidden lidocaine and capsaicin, respectively, controlled for no treatment. Healthy participants obtained a placebo effect ( P = 0.01) and a trend for a nocebo effect ( P = 0.07). Patients with AD did not obtain a placebo effect ( P = 0.44) nor a significant nocebo effect ( P = 0.86). Healthy participants expected lower and higher pain with open vs hidden lidocaine and capsaicin, respectively ( P < 0.001). The same expectation effects were seen in patients with AD (open vs hidden lidocaine, P = 0.008; open vs hidden capsaicin, P < 0.001). With a well-controlled experimental setting, this study suggests that patients with AD may not experience placebo analgesia effects. Nocebo hyperalgesia effects in patients with AD needs further research. These findings may have implications for the conduction of clinical trials and the treatment of patients with AD in clinical practice.
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Affiliation(s)
- Susan Tomczak Matthiesen
- Division for Psychology and Neuroscience, Department of Psychology and Behavioral Science, School of Business and Social Sciences, Aarhus University, Denmark
| | - Mette Sieg
- Division for Psychology and Neuroscience, Department of Psychology and Behavioral Science, School of Business and Social Sciences, Aarhus University, Denmark
| | - Stephanie Skøtt Andersen
- Division for Psychology and Neuroscience, Department of Psychology and Behavioral Science, School of Business and Social Sciences, Aarhus University, Denmark
| | | | - Nanna Brix Finnerup
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Denmark
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Hanne Gottrup
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Lene Vase
- Division for Psychology and Neuroscience, Department of Psychology and Behavioral Science, School of Business and Social Sciences, Aarhus University, Denmark
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2
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Anders B, Anders M, Kreuzer M, Zinn S, Fricker L, Maier C, Wolters M, Köhm M, Behrens F, Walter C. Sensory testing and topical capsaicin can characterize patients with rheumatoid arthritis. Clin Rheumatol 2022; 41:2351-2360. [PMID: 35499773 PMCID: PMC9059678 DOI: 10.1007/s10067-022-06185-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 04/13/2022] [Accepted: 04/19/2022] [Indexed: 11/21/2022]
Abstract
Background and objectives Our study aimed at examining the long-time inflammatory effects of rheumatoid arthritis (RA) as chronic immune-mediated disease on pain sensation and neuropathy development compared to healthy subjects (HS). Methods We used the quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain and Electroencephalography (EEG)–based contact heat evoked potentials (CHEPs) before and after topical capsaicin application. We recruited 16 RA patients in remission or low disease activity state (mean age: 59.38 years [± 10.18]) and 16 healthy subjects (mean age: 56.69 years [± 8.92]). Results The application of capsaicin cream on the thigh provoked a stronger effect in HS for both mechanical and heat pain thresholds (MPT and HPT, resp.), according to the area under the receiver operation characteristic (AUROC) (HS: HPT: 0.8965, MPT: 0.7402; RA: HPT: 0.7012, MPT: 0.6113). We observed contrary effects regarding changes in CHEPs (HS: g*max = − 0.65; RA patients: g*max = 0.72). Conclusion As the overall effect of topical capsaicin application was higher in HS for QST, we suggest the existence of a sensitization of TRPV1 channels in RA patients caused by long-time chronical inflammation, despite a lack of clinical signs of inflammation due to adequate treatment. The effect in CHEPs probably uncovers neuropathic symptoms. The effect of topical capsaicin on HPTs and CHEPs can act as a marker for the extent of sensitization and the development of neuropathic symptoms. Further studies are needed to prove if our proposed method can act as a marker for the success of anti-inflammatory treatment.Key Points • The effect of topical capsaicin may represent the extent of TRPV1 sensitization in rheumatoid arthritis. • The effect of topical capsaicin on the amplitude level of CHEPs can unmask neuropathic symptoms. • The effect of topical capsaicin on CHEPs and HPTs can show the long-term consequences and the treatment success of RA patients in remission. |
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Affiliation(s)
- Bjoern Anders
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany.
| | - Malte Anders
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Matthias Kreuzer
- Department of Anesthesiology and Intensive Care, Rechts Der Isar Hospital, Technical University of Munich School of Medicine, Ismaninger Str. 22, 81675, Munich, Germany
| | - Sebastian Zinn
- Department of Anesthesiology, Intensive-Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe University Frankfurt Am Main, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Lukas Fricker
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Christoph Maier
- University Hospital of Pediatrics and Adolescent Medicine, Ruhr-University Bochum, Bochum, Germany
| | - Miriam Wolters
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Michaela Köhm
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany.,Department of Rheumatology, Goethe University Frankfurt Am Main, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Frank Behrens
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany.,Department of Rheumatology, Goethe University Frankfurt Am Main, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Carmen Walter
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
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Improved acquisition of contact heat evoked potentials with increased heating ramp. Sci Rep 2022; 12:925. [PMID: 35042939 PMCID: PMC8766469 DOI: 10.1038/s41598-022-04867-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/29/2021] [Indexed: 12/05/2022] Open
Abstract
Contact heat evoked potentials (CHEPs) represent an objective and non-invasive measure to investigate the integrity of the nociceptive neuraxis. The clinical value of CHEPs is mostly reflected in improved diagnosis of peripheral neuropathies and spinal lesions. One of the limitations of conventional contact heat stimulation is the relatively slow heating ramp (70 °C/s). This is thought to create a problem of desynchronized evoked responses in the brain, particularly after stimulation in the feet. Recent technological advancements allow for an increased heating ramp of contact heat stimulation, however, to what extent these improve the acquisition of evoked potentials is still unknown. In the current study, 30 healthy subjects were stimulated with contact heat at the hand and foot with four different heating ramps (i.e., 150 °C/s, 200 °C/s, 250 °C/s, and 300 °C/s) to a peak temperature of 60 °C. We examined changes in amplitude, latency, and signal-to-noise ratio (SNR) of the vertex (N2-P2) waveforms. Faster heating ramps decreased CHEP latency for hand and foot stimulation (hand: F = 18.41, p < 0.001; foot: F = 4.19, p = 0.009). Following stimulation of the foot only, faster heating ramps increased SNR (F = 3.32, p = 0.024) and N2 amplitude (F = 4.38, p = 0.007). Our findings suggest that clinical applications of CHEPs should consider adopting faster heating ramps up to 250 °C/s. The improved acquisition of CHEPs might consequently reduce false negative results in clinical cohorts. From a physiological perspective, our results demonstrate the importance of peripherally synchronizing afferents recruitment to satisfactorily acquire CHEPs.
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Fabig SC, Kersebaum D, Lassen J, Sendel M, Jendral S, Muntean A, Baron R, Hüllemann P. A modality-specific somatosensory evoked potential test protocol for clinical evaluation: A feasibility study. Clin Neurophysiol 2021; 132:3104-3115. [PMID: 34740042 DOI: 10.1016/j.clinph.2021.08.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/26/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE We aimed to establish an objective neurophysiological test protocol that can be used to assess the somatosensory nervous system. METHODS In order to assess most fiber subtypes of the somatosensory nervous system, repetitive stimuli of seven different modalities (touch, vibration, pinprick, cold, contact heat, laser, and warmth) were synchronized with the electroencephalogram (EEG) and applied on the cheek and dorsum of the hand and dorsum of the foot in 21 healthy subjects and three polyneuropathy (PNP) patients. Latencies and amplitudes of the modalities were assessed and compared. Patients received quantitative sensory testing (QST) as reference. RESULTS We found reproducible evoked potentials recordings for touch, vibration, pinprick, contact-heat, and laser stimuli. The recording of warm-evoked potentials was challenging in young healthy subjects and not applicable in patients. Latencies were shortest within Aβ-fiber-mediated signals and longest within C-fibers. The test protocol detected function loss within the Aβ-fiber and Aδ-fiber-range in PNP patients. This function loss corresponded with QST findings. CONCLUSION In this pilot study, we developed a neurophysiological test protocol that can specifically assess most of the somatosensory modalities. Despite technical challenges, initial patient data appear promising regarding a possible future clinical application. SIGNIFICANCE Established and custom-made stimulators were combined to assess different fiber subtypes of the somatosensory nervous system using modality-specific evoked potentials.
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Affiliation(s)
- Sophie-Charlotte Fabig
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany.
| | - Dilara Kersebaum
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Josephine Lassen
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Manon Sendel
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Swantje Jendral
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Alexandra Muntean
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
| | - Philipp Hüllemann
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Arnold-Heller-Straße 3, Haus D, 24105 Kiel, Germany
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Measuring Latency Variations in Evoked Potential Components Using a Simple Autocorrelation Technique. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:8875445. [PMID: 34603486 PMCID: PMC8481054 DOI: 10.1155/2021/8875445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 08/28/2021] [Indexed: 11/29/2022]
Abstract
Interpretation of averaged evoked potentials is difficult when the time relationship between stimulus and response is not constant. Later components are more prone to latency jitter, making them insufficiently reliable for routine clinical use even though they could contribute to greater understanding of the functioning of polysynaptic components of the afferent nervous system. This study is aimed at providing a simple but effective method of identifying and quantifying latency jitter in averaged evoked potentials. Autocorrelation techniques were applied within defined time windows on simulated jittered signals embedded within the noise component of recorded evoked potentials and on real examples of somatosensory evoked potentials. We demonstrated that the technique accurately identifies the distribution and maximum levels of jitter of the simulated components and clearly identifies the jitter properties of real evoked potential recording components. This method is designed to complement the conventional analytical methods used in neurophysiological practice to provide valuable additional information about the distribution of latency jitter within an averaged evoked potential. It will be useful for the assessment of the reliability of averaged components and will aid the interpretation of longer-latency, polysynaptic components such as those found in nociceptive evoked potentials.
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6
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An intensity matched comparison of laser- and contact heat evoked potentials. Sci Rep 2021; 11:6861. [PMID: 33767259 PMCID: PMC7994633 DOI: 10.1038/s41598-021-85819-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 01/28/2021] [Indexed: 11/08/2022] Open
Abstract
Previous studies comparing laser (LEPs) and contact heat evoked potentials (CHEPs) consistently reported higher amplitudes following laser compared to contact heat stimulation. However, none of the studies matched the perceived pain intensity, questioning if the observed difference in amplitude is due to biophysical differences between the two methods or a mismatch in stimulation intensity. The aims of the current study were twofold: (1) to directly compare the brain potentials induced by intensity matched laser and contact heat stimulation and (2) investigate how capsaicin-induced secondary hyperalgesia modulates LEPs and CHEPs. Twenty-one healthy subjects were recruited and measured at four experimental sessions: (1) CHEPs + sham, (2) LEPs + sham, (3) CHEPs + capsaicin, and (4) LEPs + capsaicin. Baseline (sham) LEPs latency was significantly shorter and amplitude significantly larger compared to CHEPs, even when matched for perceived pain. Neither CHEPs nor LEPs was sensitive enough to detect secondary hyperalgesia. These differences provide evidence that a faster heating rate results in an earlier and more synchronized LEPs than CHEPs. To our knowledge, this was the first study to match perceived intensity of contact heat and laser stimulations, revealing distinct advantages associated with the acquisition of LEPs.
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7
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Linde LD, Haefeli J, Jutzeler CR, Rosner J, McDougall J, Curt A, Kramer JLK. Contact Heat Evoked Potentials Are Responsive to Peripheral Sensitization: Requisite Stimulation Parameters. Front Hum Neurosci 2020; 13:459. [PMID: 31998104 PMCID: PMC6966714 DOI: 10.3389/fnhum.2019.00459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/16/2019] [Indexed: 12/20/2022] Open
Abstract
The sensitizing effect of capsaicin has been previously characterized using laser and contact heat evoked potentials (LEPs and CHEPs) by stimulating in the primary area of hyperalgesia. Interestingly, only CHEPs reveal changes consistent with notion of peripheral sensitization (i.e., reduced latencies). The aim of this study was to investigate contact heat stimulation parameters necessary to detect peripheral sensitization related to the topical application of capsaicin, and therefore significantly improve the current method of measuring peripheral sensitization via CHEPs. Rapid contact heat stimulation (70°C/s) was applied from three different baseline temperatures (35, 38.5, and 42°C) to a 52°C peak temperature, before and after the topical application of capsaicin on the hand dorsum. Increased pain ratings in the primary area of hyperalgesia were accompanied by reduced N2 latency. Changes in N2 latency were, however, only significant following stimulation from 35 and 38.5°C baseline temperatures. These findings suggest that earlier recruitment of capsaicin-sensitized afferents occurs between 35 and 42°C, as stimulations from 42°C baseline were unchanged by capsaicin. This is in line with reduced thresholds of type II A-delta mechanoheat (AMH) nociceptors following sensitization. Conventional CHEP stimulation, with a baseline temperature below 42°C, is well suited to objectively detect evidence of peripheral sensitization.
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Affiliation(s)
- Lukas D Linde
- ICORD, The University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada
| | - Jenny Haefeli
- Brain and Spinal Injury Center, Department of Neurosurgery, University of California, San Francisco, San Francisco, CA, United States
| | - Catherine R Jutzeler
- ICORD, The University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.,Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Jan Rosner
- Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.,Department of Neurology, University Hospital Bern, Inselspital, University of Bern, Bern, Switzerland
| | - Jessica McDougall
- ICORD, The University of British Columbia, Vancouver, BC, Canada.,School of Rehabilitation Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Armin Curt
- Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - John L K Kramer
- ICORD, The University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada
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8
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Hüllemann P, Nerdal A, Sendel M, Dodurgali D, Forstenpointner J, Binder A, Baron R. Cold‐evoked potentials versus contact heat‐evoked potentials—Methodological considerations and clinical application. Eur J Pain 2019; 23:1209-1220. [DOI: 10.1002/ejp.1389] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 02/22/2019] [Accepted: 03/03/2019] [Indexed: 01/11/2023]
Affiliation(s)
- Philipp Hüllemann
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Annika Nerdal
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Manon Sendel
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Dilara Dodurgali
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Julia Forstenpointner
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Andreas Binder
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology University clinic Schleswig‐Holstein Kiel Germany
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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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10
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Weyer-Menkhoff I, Lötsch J. Human pharmacological approaches to TRP-ion-channel-based analgesic drug development. Drug Discov Today 2018; 23:2003-2012. [PMID: 29969684 DOI: 10.1016/j.drudis.2018.06.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 06/07/2018] [Accepted: 06/27/2018] [Indexed: 12/19/2022]
Abstract
The discovery of novel analgesic drug targets is an active research topic owing to insufficient treatment options for persisting pain. Modulators of temperature-sensing transient receptor potential ion channels (thermoTRPs), in particular TRPV1, TRPV2, TRPM8 and TRPA1, have reached clinical development. This requires access for TRP channels and the effects of specific modulators in humans. This is currently possible via (i) the study of TRP channel function in human-derived cell lines, (ii) immunohistochemical visualization of TRP channel expression in human tissues, (iii) human experimental pain models employing sensitization by means of topical application of TRP channel activators including capsaicin (TRPV1), menthol (TRPM8), mustard oil and cinnamaldehyde (TRPA1), and (iv) the study of phenotypic consequences of human TRP gene variants.
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Affiliation(s)
- Iris Weyer-Menkhoff
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
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11
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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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12
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Moskal D, Maisto SA, De Vita M, Ditre JW. Effects of experimental pain induction on alcohol urge, intention to consume alcohol, and alcohol demand. Exp Clin Psychopharmacol 2018; 26:65-76. [PMID: 29323505 PMCID: PMC5794517 DOI: 10.1037/pha0000170] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Research suggests one determinant of alcohol consumption may be physical pain, but there is no empirical evidence that pain has a causal effect on drinking. Therefore, the primary aim of this study was to test experimental pain as a determinant of several alcohol consumption proxies: self-reported urge to drink, intention to consume alcohol, and alcohol demand. This study also was designed to test negative affect as a mediator of the effects of pain on alcohol use proxies. We hypothesized that participants randomized to experimental pain induction (vs. no pain) would report greater urge, intention, and alcohol demand, and that these effects would be mediated by increased negative affect. Participants were healthy undergraduates who were moderate-heavy drinkers (N = 61). Experimental pain was induced using a novel capsaicin-heat model intended to approximate key features of clinical pain. Results indicated that participants in the pain condition subsequently endorsed greater urge and intention to drink. Furthermore, these effects were mediated by pain-induced negative affect. We observed no effect of pain on alcohol demand. This is the first study to demonstrate a causal effect of acute pain on urge and intention to drink. Given the close association between alcohol consumption, urge and intention to drink, these findings suggest that pain may influence alcohol consumption, which can have implications for individuals with co-occurring pain and alcohol use disorder (AUD). Specifically, individuals with co-occurring pain and AUD may drink to alleviate pain-related negative affect. Therefore, improving pain-coping skills may enhance pain-management abilities, subsequently reducing coping-motivated drinking. (PsycINFO Database Record
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13
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Biomarkers of neuropathic pain in skin nerve degeneration neuropathy: contact heat-evoked potentials as a physiological signature. Pain 2017; 158:516-525. [DOI: 10.1097/j.pain.0000000000000791] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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Brunner M, Löffler M, Kamping S, Bustan S, González-Roldán AM, Anton F, Flor H. Assessing Suffering in Experimental Pain Models. ZEITSCHRIFT FUR PSYCHOLOGIE-JOURNAL OF PSYCHOLOGY 2017. [DOI: 10.1027/2151-2604/a000279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Abstract. Although suffering is a central issue in pain, there is only little research on this topic. The aim of this study was to assess suffering in an experimental context using various stimulation methods and durations, and to examine which psychological or psychophysiological measures covary with pain-related suffering. Twenty-one healthy volunteers participated in two experiments in which we used tonic thermal and phasic electric stimuli with short and long stimulus durations. The participants rated pain intensity, unpleasantness, and pain-related suffering on separate visual analog scales (VAS) and completed the Pictorial Representation of Illness and Self Measure (PRISM), originally developed to assess suffering in chronic illness. We measured heart rate, skin conductance responses (SCRs), and the electromyogram (EMG) of the musculus corrugator supercilii. For both heat and electric pain, we obtained high ratings on the suffering scale confirming that suffering can be evoked in experimental pain conditions. Whereas pain intensity and unpleasantness were highly correlated, both scales were less highly related to suffering, indicating that suffering is distinct from pain intensity and unpleasantness. Higher suffering ratings were associated with more pronounced fear of pain and increased private self-consciousness. Pain-related suffering was also related to high resting heart rate, increased SCR, and decreased EMG during painful stimulation. These results offer an approach to the assessment of suffering in an experimental setting using thermal and electric pain stimulation and shed light on its psychological and psychophysiological correlates.
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Affiliation(s)
- M. Brunner
- Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - M. Löffler
- Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - S. Kamping
- Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - S. Bustan
- Institute for Health and Behavior, FLSHASE/INSIDE, University of Luxembourg, Luxembourg
| | - A. M. González-Roldán
- Institute for Health and Behavior, FLSHASE/INSIDE, University of Luxembourg, Luxembourg
| | - F. Anton
- Institute for Health and Behavior, FLSHASE/INSIDE, University of Luxembourg, Luxembourg
| | - H. Flor
- Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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15
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Fardo F, Vinding MC, Allen M, Jensen TS, Finnerup NB. Delta and gamma oscillations in operculo-insular cortex underlie innocuous cold thermosensation. J Neurophysiol 2017; 117:1959-1968. [PMID: 28250150 PMCID: PMC5411475 DOI: 10.1152/jn.00843.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/07/2017] [Accepted: 02/07/2017] [Indexed: 01/21/2023] Open
Abstract
Using magnetoencephalography, we identified spatiotemporal features of central cold processing, with respect to the time course, oscillatory profile, and neural generators of cold-evoked responses in healthy human volunteers. Cold thermosensation was associated with low- and high-frequency oscillatory rhythms, both originating in operculo-insular regions. These results support further investigations of central cold processing using magnetoencephalography or EEG and the clinical utility of cold-evoked potentials for neurophysiological assessment of cold-related small-fiber function and damage. Cold-sensitive and nociceptive neural pathways interact to shape the quality and intensity of thermal and pain perception. Yet the central processing of cold thermosensation in the human brain has not been extensively studied. Here, we used magnetoencephalography and EEG in healthy volunteers to investigate the time course (evoked fields and potentials) and oscillatory activity associated with the perception of cold temperature changes. Nonnoxious cold stimuli consisting of Δ3°C and Δ5°C decrements from an adapting temperature of 35°C were delivered on the dorsum of the left hand via a contact thermode. Cold-evoked fields peaked at around 240 and 500 ms, at peak latencies similar to the N1 and P2 cold-evoked potentials. Importantly, cold-related changes in oscillatory power indicated that innocuous thermosensation is mediated by oscillatory activity in the range of delta (1–4 Hz) and gamma (55–90 Hz) rhythms, originating in operculo-insular cortical regions. We suggest that delta rhythms coordinate functional integration between operculo-insular and frontoparietal regions, while gamma rhythms reflect local sensory processing in operculo-insular areas. NEW & NOTEWORTHY Using magnetoencephalography, we identified spatiotemporal features of central cold processing, with respect to the time course, oscillatory profile, and neural generators of cold-evoked responses in healthy human volunteers. Cold thermosensation was associated with low- and high-frequency oscillatory rhythms, both originating in operculo-insular regions. These results support further investigations of central cold processing using magnetoencephalography or EEG and the clinical utility of cold-evoked potentials for neurophysiological assessment of cold-related small-fiber function and damage.
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Affiliation(s)
- Francesca Fardo
- Danish Pain Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; .,Interacting Minds Centre, Aarhus University, Aarhus, Denmark.,Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Mikkel C Vinding
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark.,Swedish National Facility for Magnetoencephalography, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Micah Allen
- Wellcome Trust Center for Neuroimaging, University College London, London, United Kingdom.,Institute of Cognitive Neuroscience, University College London, London, United Kingdom; and
| | - Troels Staehelin Jensen
- Danish Pain Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Nanna Brix Finnerup
- Danish Pain Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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16
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Liu N, Shimizu S, Shimizu T, Nakamura K, Yamamoto M, Higashi Y, Saito M. Protective effects of the selective alpha1A-adrenoceptor antagonist silodosin against cyclophosphamide-induced cystitis in rats. J Pharmacol Sci 2016; 132:71-77. [DOI: 10.1016/j.jphs.2016.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/14/2016] [Accepted: 08/28/2016] [Indexed: 12/30/2022] Open
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17
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Springer J, Karlsson P, Madsen C, Johnsen B, Finnerup N, Jensen T, Nikolajsen L. Functional and structural assessment of patients with and without persistent pain after thoracotomy. Eur J Pain 2016; 21:238-249. [DOI: 10.1002/ejp.919] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2016] [Indexed: 12/12/2022]
Affiliation(s)
- J.S. Springer
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
- Department of Neurology; Aarhus University Hospital; Denmark
| | - P. Karlsson
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
| | - C.S. Madsen
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
| | - B. Johnsen
- Department of Clinical Neurophysiology; Aarhus University Hospital; Denmark
| | - N.B. Finnerup
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
| | - T.S. Jensen
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
- Department of Neurology; Aarhus University Hospital; Denmark
| | - L. Nikolajsen
- Danish Pain Research Center; Department of Clinical Medicine; Aarhus University; Denmark
- Department of Anaesthesiology; Aarhus University Hospital; Denmark
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18
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Hüllemann P, Nerdal A, Binder A, Helfert S, Reimer M, Baron R. Cold-evoked potentials - Ready for clinical use? Eur J Pain 2016; 20:1730-1740. [DOI: 10.1002/ejp.896] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2016] [Indexed: 11/12/2022]
Affiliation(s)
- P. Hüllemann
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
| | - A. Nerdal
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
| | - A. Binder
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
| | - S. Helfert
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
| | - M. Reimer
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
| | - R. Baron
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Clinic Schleswig-Holstein; Campus Kiel Germany
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19
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A randomized, double-blind, positive-controlled, 3-way cross-over human experimental pain study of a TRPV1 antagonist (V116517) in healthy volunteers and comparison with preclinical profile. Pain 2016; 157:2057-2067. [DOI: 10.1097/j.pain.0000000000000610] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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20
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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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21
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Jensen-Dahm C, Madsen CS, Waldemar G, Ballegaard M, Hejl AM, Johnsen B, Jensen TS. Contact Heat Evoked Potentials (CHEPs) in Patients with Mild-Moderate Alzheimer's Disease and Matched Control--A Pilot Study. PAIN MEDICINE 2015; 17:675-84. [PMID: 26814248 DOI: 10.1093/pm/pnv012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Clinical studies have found that patients with Alzheimer's disease report pain of less intensity and with a lower affective response, which has been thought to be due to altered pain processing. The authors wished to examine the cerebral processing of non-painful and painful stimuli using somatosensory evoked potentials and contact heat evoked potentials in patients with Alzheimer's disease and in healthy elderly controls. DESIGN Case-control study SETTING AND SUBJECTS Twenty outpatients with mild-moderate Alzheimer's disease and in 17 age- and gender-matched healthy controls were included METHOD Contact heat evoked potentials and somatosensory evoked potentials were recorded in all subjects. Furthermore, warmth detection threshold and heat pain threshold were assessed. Patients and controls also rated quality and intensity of the stimuli. RESULTS The authors found no difference on contact heat evoked potential amplitude (P = 0.59) or latency of N2 or P2 wave (P = 0.62 and P = 0.75, respectively) between patients and controls. In addition, there was no difference in regard to pain intensity scores or pain quality. The patients and controls had similar warmth detection threshold and heat pain threshold. Somatosensory evoked potentials, amplitude, and latency were within normal range and similar for the two groups. CONCLUSIONS The findings suggest that the processing of non-painful and painful stimuli is preserved in patients with mild to moderate Alzheimer's disease.
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Affiliation(s)
- Christina Jensen-Dahm
- *Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark;
| | - Caspar Skau Madsen
- Danish Pain Research Centre, Department of Neurology, Aarhus University Hospital, Denmark
| | - Gunhild Waldemar
- *Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Martin Ballegaard
- Department of Clinical Neurophysiology, Rigshospitalet, University of Copenhagen, Denmark
| | - Anne-Mette Hejl
- *Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Birger Johnsen
- Department of Clinical Neurophysiology, Aarhus University Hospital, Denmark
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22
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Altered thermal grill response and paradoxical heat sensations after topical capsaicin application. Pain 2015; 156:1101-1111. [DOI: 10.1097/j.pain.0000000000000155] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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23
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Jutzeler CR, Curt A, Kramer JLK. Effectiveness of High-Frequency Electrical Stimulation Following Sensitization With Capsaicin. THE JOURNAL OF PAIN 2015; 16:595-605. [PMID: 25866256 DOI: 10.1016/j.jpain.2015.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/16/2015] [Accepted: 03/13/2015] [Indexed: 11/26/2022]
Abstract
UNLABELLED Although nonnoxious, high-frequency electrical stimulation applied segmentally (ie, conventional transcutaneous electrical nerve stimulation [TENS]) has been proposed to modulate pain, the mechanisms underlying analgesia remain poorly understood. To further elucidate how TENS modulates pain, we examined evoked responses to noxious thermal stimuli after the induction of sensitization using capsaicin in healthy volunteers. We hypothesized that sensitization caused by capsaicin application would unmask TENS analgesia, which could not be detected in the absence of sensitization. Forty-nine healthy subjects took part in a series of experiments. The experiments comprised the application of topical capsaicin (.075%) on the left hand in the C6 dermatome, varying the location of TENS (segmental, left C6 dermatome, vs extrasegmental, right shoulder), and assessing rating of perception (numeric rating scale: 0-10) and evoked potentials to noxious contact heat stimuli. The extrasegmental site was included as a control condition because previous studies indicate no analgesic effect to remote conventional TENS. Conventional TENS had no significant effect on rating or sensory evoked potentials in subjects untreated with capsaicin. However, segmental TENS applied in conjunction with capsaicin significantly reduced sensation to noxious thermal stimuli following a 60-minute period of sensitization. PERSPECTIVE The study indicates that sensitization with capsaicin unmasks the analgesic effect of conventional TENS on perception of noxious contact heat stimuli. Our findings indicate that TENS may be interacting segmentally to modulate distinct aspects of sensitization, which in turn results in analgesia to thermal stimulation.
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Affiliation(s)
- Catherine R Jutzeler
- Spinal Cord Injury Center, University Hospital Balgrist, University of Zurich, Zurich, Switzerland.
| | - Armin Curt
- Spinal Cord Injury Center, University Hospital Balgrist, University of Zurich, Zurich, Switzerland
| | - John L K Kramer
- Spinal Cord Injury Center, University Hospital Balgrist, University of Zurich, Zurich, Switzerland; School of Kinesiology, International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
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24
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Gilron I, Baron R, Jensen T. Neuropathic pain: principles of diagnosis and treatment. Mayo Clin Proc 2015; 90:532-45. [PMID: 25841257 DOI: 10.1016/j.mayocp.2015.01.018] [Citation(s) in RCA: 332] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 12/14/2022]
Abstract
Neuropathic pain is caused by disease or injury of the nervous system and includes various chronic conditions that, together, affect up to 8% of the population. A substantial body of neuropathic pain research points to several important contributory mechanisms including aberrant ectopic activity in nociceptive nerves, peripheral and central sensitization, impaired inhibitory modulation, and pathological activation of microglia. Clinical evaluation of neuropathic pain requires a thorough history and physical examination to identify characteristic signs and symptoms. In many cases, other laboratory investigations and clinical neurophysiological testing may help identify the underlying etiology and guide treatment selection. Available treatments essentially provide only symptomatic relief and may include nonpharmacological, pharmacological, and interventional therapies. Most extensive evidence is available for pharmacological treatment, and currently recommended first-line treatments include antidepressants (tricyclic agents and serotonin-norepinephrine reuptake inhibitors) and anticonvulsants (gabapentin and pregabalin). Individualized multidisciplinary patient care is facilitated by careful consideration of pain-related disability (eg, depression and occupational dysfunction) as well as patient education; repeat follow-up and strategic referral to appropriate medical/surgical subspecialties; and physical and psychological therapies. In the near future, continued preclinical and clinical research and development are expected to lead to further advancements in the diagnosis and treatment of neuropathic pain.
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Affiliation(s)
- Ian Gilron
- Departments of Anesthesiology and Perioperative Medicine and Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Troels Jensen
- Department of Neurology and Danish Pain Research Center, Aarhus University Hospital, Aarhus C, Denmark
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25
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Karlsson P, Nyengaard JR, Polydefkis M, Jensen TS. Structural and functional assessment of skin nerve fibres in small-fibre pathology. Eur J Pain 2014; 19:1059-70. [PMID: 25546653 DOI: 10.1002/ejp.645] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2014] [Indexed: 01/19/2023]
Abstract
Damage to nociceptor nerve fibres may give rise to peripheral neuropathies, some of which are pain free and some are painful. A hallmark of many peripheral neuropathies is the loss of small nerve fibres in the epidermis, a condition called small-fibre neuropathy (SFN) when it is predominantly the small nerve fibres that are damaged. Historically, SFN has been very difficult to diagnose as clinical examination and nerve conduction studies mainly detect large nerve fibres, and quantitative sensory testing is not sensitive enough to detect small changes in small nerve fibres. However, taking a 3-mm punch skin biopsy from the distal leg and quantification of the nerve fibre density has proven to be a useful method to diagnose SFN. However, the correlation between the nerve fibre loss and other test results varies greatly. Recent studies have shown that it is possible not only to extract information about the nerve fibre density from the biopsies but also to get an estimation of the nerve fibre length density using stereology, quantify sweat gland innervation and detect morphological changes such as axonal swelling, all of which may be additional parameters indicating diseased small fibres relating to symptoms reported by the patients. In this review, we focus on available tests to assess structure and function of the small nerve fibres, and summarize recent advances that have provided new possibilities to more specifically relate structural findings with symptoms and function in patients with SFN.
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Affiliation(s)
- P Karlsson
- Danish Pain Research Center and Stereology & EM Laboratory, Aarhus University Hospital, Denmark.,Stereology and Electron Microscopy Laboratory and Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, Denmark
| | - J R Nyengaard
- Stereology and Electron Microscopy Laboratory and Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, Denmark
| | - M Polydefkis
- Department of Neurology, The Johns Hopkins Hospital, Baltimore, MD, USA
| | - T S Jensen
- Danish Pain Research Center and Stereology & EM Laboratory, Aarhus University Hospital, Denmark.,Department of Neurology, Aarhus University Hospital, Denmark
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26
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Schaldemose EL, Horjales-Araujo E, Demontis D, Børglum AD, Svensson P, Finnerup NB. No association of polymorphisms in the serotonin transporter gene with thermal pain sensation in healthy individuals. Mol Pain 2014; 10:76. [PMID: 25472558 PMCID: PMC4364075 DOI: 10.1186/1744-8069-10-76] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/19/2014] [Indexed: 12/21/2022] Open
Abstract
Background Recent studies have suggested an association between genotypes affecting the expression of the serotonin transporter and thermal pain perception and the thermal grill. The aim of this study was to investigate differences in thermal and mechanical pain perception and the thermal grill in two groups of healthy volunteers according to their genotype, associated with either high (n = 40) or low (n = 40) expression of the serotonin transporter and according to gender. Cold and warm detection and pain thresholds, pressure pain threshold and cold, warm and pain sensations to single or alternating stimuli with cold (20°C) and warm (40°C) temperatures (known as the thermal grill) were determined. In addition, intensity of ongoing pain and area and intensity of pinprick hyperalgesia in the secondary hyperalgesic area following topical application of capsaicin and vehicle control (ethanol) were determined. Results No significant differences in detection and pain thresholds for cold and warm temperatures, presence of paradoxical heat sensation, pressure pain threshold and pain responses to suprathreshold thermal stimuli were observed. There was also no difference in capsaicin-evoked ongoing pain and secondary hyperalgesia between the two genotype groups (p >0.4), also when subdivided by gender (p >0.17). In addition, there were no significant differences in the perception of the thermal grill between the two genotypes (p >0.5), also when subdivided by gender. Conclusions Genotypes associated with high or low expression of the serotonin transporter were not associated with thermal pain thresholds, pressure pain threshold, pain after capsaicin application or responses to the thermal grill. The present results do not support that the investigated genotypes play a major role in thermal pain perception among healthy individuals.
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Affiliation(s)
- Ellen Lund Schaldemose
- Danish Pain Research Center, Aarhus University Hospital, Norrebrogade 44, Building 1A, DK-8000 Aarhus C, Denmark.
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27
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Expectations and positive emotional feelings accompany reductions in ongoing and evoked neuropathic pain following placebo interventions. Pain 2014; 155:2687-2698. [PMID: 25281929 DOI: 10.1016/j.pain.2014.09.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/22/2014] [Accepted: 09/25/2014] [Indexed: 12/31/2022]
Abstract
Research on placebo analgesia and nocebo hyperalgesia has primarily included healthy subjects or acute pain patients, and it is unknown whether these effects can be obtained in ongoing pain in patients with chronic pain caused by an identifiable nerve injury. Eighteen patients with postthoracotomy neuropathic pain were exposed to placebo and nocebo manipulations, in which they received open and hidden administrations of pain-relieving (lidocaine) or pain-inducing (capsaicin) treatment controlled for the natural history of pain. Immediately after the open administration, patients rated their expected pain levels on a mechanical visual analogue scale (M-VAS). They also reported their emotional feelings via a quantitative/qualitative experiential method. Subsequently, patients rated their ongoing pain levels on the M-VAS and underwent quantitative sensory testing of evoked pain (brush, pinprick, area of hyperalgesia, wind-up-like pain). There was a significant placebo effect on both ongoing (P=.009 to .019) and evoked neuropathic pain (P=.0005 to .053). Expected pain levels accounted for significant amounts of the variance in ongoing (53.4%) and evoked pain (up to 34.5%) after the open lidocaine administration. Furthermore, patients reported high levels of positive and low levels of negative emotional feelings in the placebo condition compared with the nocebo condition (P⩽.001). Pain increases during nocebo were nonsignificant (P=.394 to 1.000). To our knowledge, this is the first study to demonstrate placebo effects in ongoing neuropathic pain. It provides further evidence for placebo-induced reduction in hyperalgesia and suggests that patients' expectations coexist with emotional feelings about treatments.
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28
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Pluijms WA, Slangen R, van Kleef M, Joosten EA, Reulen JPH. Increased contact heat evoked potential stimulation latencies in responders to spinal cord stimulation for painful diabetic polyneuropathy. Neuromodulation 2014; 18:126-32; discussion 132. [PMID: 24945509 DOI: 10.1111/ner.12188] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/24/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To analyze sensory characteristics and small nerve fiber function in patients suffering from painful diabetic polyneuropathy (PDP) and compare outcomes in responders and nonresponders to SCS treatment. METHODS Fifteen patients with intractable PDP in the legs were recruited. If trial stimulation resulted in clinically relevant pain relief, a pulse generator was implanted and pain scores were measured after 12 months. Sensory characteristics (modified Inflammatory Neuropathy Cause and Treatment [md-INCAT] sum score) and small nerve fiber function (contact heat evoked potentials, CHEPs) were measured before implantation (D1), and CHEP measurement was repeated after two weeks of trial stimulation (D2). Outcomes in responders (N = 10) and nonresponders (N = 5) to SCS treatment were compared. Data were analyzed using nonparametric statistics. RESULTS At one year, clinically relevant pain relief was achieved in 10 out of 15 patients. The md-INCAT score did not differ between SCS responders and nonresponders (8.0 vs. 5.0; p = 0.59). No differences were found in CHEP outcomes at D1 vs. D2, except for dorsal forearm P2 latency, and the correlation between D1 and D2 CHEP outcomes was high. Volar N2 forearm latency (0.492 vs. 0.434; p < 0.01), dorsal forearm N2 latency (0.518 vs. 0.453; p = 0.04), and dorsal forearm P2 latency (0.660 vs. 0.589; p = 0.04) were increased in SCS responders as compared with SCS nonresponders. CONCLUSIONS From this small-scale clinical pilot study we conclude that forearm CHEP latencies are increased in PDP patients who respond to SCS therapy as compared with SCS nonresponders. Before the CHEP latency can be used as a predictor of SCS outcome in PDP patients, a large-scale study is needed.
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Affiliation(s)
- Wouter A Pluijms
- Department of Anesthesiology and Pain Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
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29
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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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Iannetti GD, Baumgärtner U, Tracey I, Treede RD, Magerl W. Pinprick-evoked brain potentials: a novel tool to assess central sensitization of nociceptive pathways in humans. J Neurophysiol 2013; 110:1107-16. [DOI: 10.1152/jn.00774.2012] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Although hyperalgesia to mechanical stimuli is a frequent sign in patients with inflammation or neuropathic pain, there is to date no objective electrophysiological measure for its evaluation in the clinical routine. Here we describe a technique for recording the electroencephalographic (EEG) responses elicited by mechanical stimulation with a flat-tip probe (diameter 0.25 mm, force 128 mN). Such probes activate Aδ nociceptors and are widely used to assess the presence of secondary hyperalgesia, a psychophysical correlate of sensitization in the nociceptive system. The corresponding pinprick-evoked potentials (PEPs) were recorded in 10 subjects during stimulation of the right and left hand dorsum before and after intradermal injection of capsaicin into the right hand and in 1 patient with a selective lesion of the right spinothalamic tract. PEPs in response to stimulation of normal skin were characterized by a vertex negative-positive (NP) complex, with N/P latencies and amplitudes of 111/245 ms and 3.5/11 μV, respectively. All subjects developed a robust capsaicin-induced increase in the pain elicited by pinprick stimulation of the secondary hyperalgesic area (+91.5%, P < 0.005). Such stimulation also resulted in a significant increase of the N-wave amplitude (+92.9%, P < 0.005), but not of the P wave (+6.6%, P = 0.61). In the patient, PEPs during stimulation of the hypoalgesic side were reduced. These results indicate that PEPs 1) reflect cortical activities triggered by somatosensory input transmitted in Aδ primary sensory afferents and spinothalamic projection neurons, 2) allow quantification of experimentally induced secondary mechanical hyperalgesia, and 3) have the potential to become a diagnostic tool to substantiate mechanical hyperalgesia in patients with presumed central sensitization.
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Affiliation(s)
- G. D. Iannetti
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - U. Baumgärtner
- Chair of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Mannheim, Germany; and
| | - I. Tracey
- FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom
| | - R. D. Treede
- Chair of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Mannheim, Germany; and
| | - W. Magerl
- Chair of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Mannheim, Germany; and
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Fabrizi L, Williams G, Lee A, Meek J, Slater R, Olhede S, Fitzgerald M. Cortical activity evoked by an acute painful tissue-damaging stimulus in healthy adult volunteers. J Neurophysiol 2013; 109:2393-403. [PMID: 23427303 PMCID: PMC3652217 DOI: 10.1152/jn.00990.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/18/2013] [Indexed: 12/25/2022] Open
Abstract
Everyday painful experiences are usually single events accompanied by tissue damage, and yet most experimental studies of cutaneous nociceptive processing in the brain use repeated laser, thermal, or electrical stimulations that do not damage the skin. In this study the nociceptive activity in the brain evoked by tissue-damaging skin lance was analyzed with electroencephalography (EEG) in 20 healthy adult volunteers (13 men and 7 women) aged 21-40 yr. Time-frequency analysis of the evoked activity revealed a distinct late event-related vertex potential (lance event-related potential, LERP) at 100-300 ms consisting of a phase-locked energy increase between 1 and 20 Hz (delta-beta bands). A pairwise comparison between lance and sham control stimulation also revealed a period of ultralate stronger desynchronization after lance in the delta band (1-5 Hz). Skin application of mustard oil before lancing, which sensitizes a subpopulation of nociceptors expressing the cation channel TRPA1, did not affect the ultralate desynchronization but reduced the phase-locked energy increase in delta and beta bands, suggesting a central interaction between different modalities of nociceptive inputs. Verbal descriptor screening of individual pain experience revealed that lance pain is predominantly due to Aδ fiber activation, but when individuals describe lances as C fiber mediated, an ultralate delta band event-related desynchronization occurs in the brain-evoked activity. We conclude that pain evoked by acute tissue damage is associated with distinct Aδ and C fiber-mediated patterns of synchronization and desynchronization of EEG oscillations in the brain.
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Affiliation(s)
- Lorenzo Fabrizi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
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Improving the acquisition of nociceptive evoked potentials without causing more pain. Pain 2013; 154:235-241. [DOI: 10.1016/j.pain.2012.10.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 09/07/2012] [Accepted: 10/18/2012] [Indexed: 11/19/2022]
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Madsen C, Johnsen B, Fuglsang-Frederiksen A, Jensen T, Finnerup N. The effect of nerve compression and capsaicin on contact heat-evoked potentials related to Aδ- and C-fibers. Neuroscience 2012; 223:92-101. [DOI: 10.1016/j.neuroscience.2012.07.049] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/17/2012] [Accepted: 07/19/2012] [Indexed: 10/28/2022]
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Baumgärtner U, Greffrath W, Treede RD. Contact heat and cold, mechanical, electrical and chemical stimuli to elicit small fiber-evoked potentials: Merits and limitations for basic science and clinical use. Neurophysiol Clin 2012; 42:267-80. [DOI: 10.1016/j.neucli.2012.06.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 06/05/2012] [Accepted: 06/25/2012] [Indexed: 12/13/2022] Open
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