The pathophysiology of many orofacial pain syndromes is still unclear. We investigated the effect of tonic muscle and skin pain on the excitability of the trigeminal motor pathways using transcranial magnetic stimulation (TMS). Motor evoked potentials (MEPs) were recorded in the masseter surface electromyogram (EMG). Magnetic pulses were delivered with a large coil at intensities 1.1 and 1.5 times the motor threshold, and for each intensity, MEPs were recorded at three different clenching levels: 15, 30 and 45% of maximum voluntary contraction (MVC). Baseline, pain and post-baseline recordings were compared in two sessions. Firstly, muscle pain was induced by infusion of hypertonic saline (5.8%) into the left masseter. Secondly, skin pain was induced by topical application of capsaicin (5%) on the left cheek. Muscle and skin pain did not induce significant effects on the amplitude or latency of the MEPs (ANOVAs: P>0.50). In both sessions, the amplitude of the MEPs increased with the increase of the clenching level and stimulus intensity (P<0.0001; P<0.005) whereas the latency was not significantly changed (P>0.05; P=0.11). Muscle pain was associated with an increase in the pre-stimulus EMG activity on the non-painful side compared with baseline (P<0.01), which could be due to compensatory changes in the activation of the painful muscle. The need for voluntary contraction to evoke MEPs in the masseter muscles and compensatory mechanisms both at the brainstem and cortical level might explain the lack of detectable modulation of MEPs. Nonetheless, the present findings did not support the so-called 'vicious cycle' between pain - central hyperexcitability - muscle hyperactivity. (C) 2000 Elsevier Science B.V. All rights reserved.

Effect of experimental pain from trigeminal muscle and skin on motor cortex excitability in humans / Antonietta, Romaniello; Cruccu, Giorgio; Anne S., Mcmillan; Lars Arendt, Nielsen; Peter, Svensson. - In: BRAIN RESEARCH. - ISSN 0006-8993. - 882:1-2(2000), pp. 120-127. [10.1016/s0006-8993(00)02856-0]

Effect of experimental pain from trigeminal muscle and skin on motor cortex excitability in humans

CRUCCU, Giorgio;
2000

Abstract

The pathophysiology of many orofacial pain syndromes is still unclear. We investigated the effect of tonic muscle and skin pain on the excitability of the trigeminal motor pathways using transcranial magnetic stimulation (TMS). Motor evoked potentials (MEPs) were recorded in the masseter surface electromyogram (EMG). Magnetic pulses were delivered with a large coil at intensities 1.1 and 1.5 times the motor threshold, and for each intensity, MEPs were recorded at three different clenching levels: 15, 30 and 45% of maximum voluntary contraction (MVC). Baseline, pain and post-baseline recordings were compared in two sessions. Firstly, muscle pain was induced by infusion of hypertonic saline (5.8%) into the left masseter. Secondly, skin pain was induced by topical application of capsaicin (5%) on the left cheek. Muscle and skin pain did not induce significant effects on the amplitude or latency of the MEPs (ANOVAs: P>0.50). In both sessions, the amplitude of the MEPs increased with the increase of the clenching level and stimulus intensity (P<0.0001; P<0.005) whereas the latency was not significantly changed (P>0.05; P=0.11). Muscle pain was associated with an increase in the pre-stimulus EMG activity on the non-painful side compared with baseline (P<0.01), which could be due to compensatory changes in the activation of the painful muscle. The need for voluntary contraction to evoke MEPs in the masseter muscles and compensatory mechanisms both at the brainstem and cortical level might explain the lack of detectable modulation of MEPs. Nonetheless, the present findings did not support the so-called 'vicious cycle' between pain - central hyperexcitability - muscle hyperactivity. (C) 2000 Elsevier Science B.V. All rights reserved.
2000
adult; analysis of variance; capsaicin; chemically induced/physiopathology; electromagnetic phenomena; electromyography; evoked potentials; experimental pain; facial muscles; facial pain; female; humans; hypertonic; male; masseter muscle; motor; motor cortex; muscle tonus; pharmacology; physiology; physiopathology; saline solution; skin; transcranial magnetic stimulation; trigeminal nerve; trigeminal physiology
01 Pubblicazione su rivista::01a Articolo in rivista
Effect of experimental pain from trigeminal muscle and skin on motor cortex excitability in humans / Antonietta, Romaniello; Cruccu, Giorgio; Anne S., Mcmillan; Lars Arendt, Nielsen; Peter, Svensson. - In: BRAIN RESEARCH. - ISSN 0006-8993. - 882:1-2(2000), pp. 120-127. [10.1016/s0006-8993(00)02856-0]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/405587
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 11
  • Scopus 75
  • ???jsp.display-item.citation.isi??? 65
social impact