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Leone C, Di Lionardo A, Di Pietro G, Di Stefano G, Falco P, Blockeel AJ, Caspani O, Garcia-Larrea L, Mouraux A, Phillips KG, Treede RD, Truini A. How different experimental models of secondary hyperalgesia change the nociceptive flexion reflex. Clin Neurophysiol 2021; 132:2989-2995. [PMID: 34715423 DOI: 10.1016/j.clinph.2021.08.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/05/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE In this neurophysiological study in healthy humans, we assessed how central sensitization induced by either high-frequency stimulation (HFS) or topical capsaicin application modulates features of the RIII reflex response. The ability of these stimuli to engage the endogenous pain modulatory system was also tested. METHODS In 26 healthy participants we elicited an RIII reflex using suprathreshold stimulation of the sural nerve. Subsequently HFS or capsaicin were applied to the foot and the RIII reflex repeated after 15 minutes. Contact heating of the volar forearm served as the heterotopic test stimulus to probe activation of the endogenous pain modulatory system. RESULTS HFS significantly reduced the pain threshold by 29% and the RIII reflex threshold by 20%. Capsaicin significantly reduced the pain threshold by 17% and the RIII reflex threshold by 18%. Both HFS and capsaicin left RIII reflex size unaffected. Numerical Rating Scale (NRS) pain scores elicited by the heterotopic noxious heat stimulus were unaffected by capsaicin and slightly increased by HFS. CONCLUSIONS HFS and capsaicin similarly modulated the pain threshold and RIII reflex threshold, without a concomitant inhibitory effect of the endogenous pain modulatory system. SIGNIFICANCE Our neurophysiological study supports the use of the RIII reflex in investigating central sensitization in humans.
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Affiliation(s)
- C Leone
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - A Di Lionardo
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - G Di Pietro
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - G Di Stefano
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - P Falco
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - A J Blockeel
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - O Caspani
- Department of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany
| | - L Garcia-Larrea
- Lyon Neurosciences Center Research Unit Inserm U 1028, Pierre Wertheimer Hospital, Hospices Civils de Lyon, Lyon 1 University, Lyon, France; Pain Center, Pierre Wertheimer Hospital, Hospices Civils de Lyon, Lyon 1 University, Lyon, France
| | - A Mouraux
- Université Catholique de Louvain, Institute of Neuroscience (IoNS), Faculty of Medicine, Bruxelles, Belgium
| | - K G Phillips
- Lilly United Kingdom Erl Wood Manor Windlesham, Surrey, United Kingdom
| | - R D Treede
- Department of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany
| | - A Truini
- Department of Human Neuroscience, Sapienza University, Rome, Italy.
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Di Lionardo A, Di Stefano G, Leone C, Di Pietro G, Sgro E, Malara E, Cosentino C, Mollica C, Blockeel AJ, Caspani O, Garcia-Larrea L, Mouraux A, Treede RD, Phillips KG, Valeriani M, Truini A. Modulation of the N13 component of the somatosensory evoked potentials in an experimental model of central sensitization in humans. Sci Rep 2021; 11:20838. [PMID: 34675309 PMCID: PMC8531029 DOI: 10.1038/s41598-021-00313-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 10/01/2021] [Indexed: 11/09/2022] Open
Abstract
The N13 component of somatosensory evoked potential (N13 SEP) represents the segmental response of dorsal horn neurons. In this neurophysiological study, we aimed to verify whether N13 SEP might reflect excitability changes of dorsal horn neurons during central sensitization. In 22 healthy participants, we investigated how central sensitization induced by application of topical capsaicin to the ulnar nerve territory of the hand dorsum modulated N13 SEP elicited by ulnar nerve stimulation. Using a double-blind placebo-controlled crossover design, we also tested whether pregabalin, an analgesic drug with proven efficacy on the dorsal horn, influenced capsaicin-induced N13 SEP modulation. Topical application of capsaicin produced an area of secondary mechanical hyperalgesia, a sign of central sensitization, and increased the N13 SEP amplitude but not the peripheral N9 nor the cortical N20-P25 amplitude. This increase in N13 SEP amplitude paralleled the mechanical hyperalgesia and persisted for 120 min. Pregabalin prevented the N13 SEP modulation associated with capsaicin-induced central sensitization, whereas capsaicin application still increased N13 SEP amplitude in the placebo treatment session. Our neurophysiological study showed that capsaicin application specifically modulates N13 SEP and that this modulation is prevented by pregabalin, thus suggesting that N13 SEP may reflect changes in dorsal horn excitability and represent a useful biomarker of central sensitization in human studies.
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Affiliation(s)
- A Di Lionardo
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - G Di Stefano
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - C Leone
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - G Di Pietro
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - E Sgro
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - E Malara
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - C Cosentino
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy
| | - C Mollica
- Department of Statistical Sciences, Sapienza University, Rome, Italy
| | - A J Blockeel
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - O Caspani
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - L Garcia-Larrea
- Lyon Neurosciences Center Research Unit Inserm U 1028, Pierre Wertheimer Hospital, Hospices Civils de Lyon, Lyon 1 University, Lyon, France.,Pain Center, Pierre Wertheimer Hospital, Hospices Civils de Lyon, Lyon 1 University, Lyon, France
| | - A Mouraux
- UCLouvain, Institute of Neuroscience (IoNS), Brussels, Belgium
| | - R D Treede
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - K G Phillips
- Neuroscience Next Generation Therapeutics, Eli Lilly and Company, Lilly Innovation Center, Cambridge, MA, 02142, USA
| | - M Valeriani
- Department of Neuroscience, Headache Center, Bambino Gesù Children's Hospital, Rome, Italy.,Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark
| | - Andrea Truini
- Department of Human Neuroscience, University Sapienza, Viale Università 30, 00185, Rome, Italy.
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