This study tested the hypothesis that painful injections of glutamate into the human masseter muscle differentially affect the distribution of the electromyographic (EMG) activity in the masseter muscle at rest and during tooth clenching. Surface EMG signals were recorded bilaterally from the superficial masseter of nine healthy men with a grid of 32 electrodes, before and after intramuscular injection of glutamate or isotonic saline, during rest and isometric contractions at 20%, 40%, 60% and 80% of the maximal voluntary bite force. Intramuscular injection of glutamate evoked moderate pain (0-10 visual analogue scale: 6·4 ± 1·4), with sensory-discriminative characteristics of the perceived pain, evaluated with the use of the McGill Pain Questionnaire (MPQ), similar to those previously reported for patients with temporomandibular disorders. There was no effect of the glutamate injection on EMG amplitude during rest, whereas during tooth clenching, the spatial distribution of the masseter EMG activity on both sides was more uniform in the painful condition compared to the control condition. Moreover, the overall EMG amplitude decreased on both sides during the more forceful tooth clenching following glutamate injection. In conclusion, a unilateral painful stimulation was associated with a bilateral inhibition of the masseter muscles during tooth clenching which resulted in a more uniform distribution of EMG activity.
Titolo: | Effect of experimental jaw-muscle pain on the spatial distribution of surface EMG activity of the human masseter muscle during tooth clenching |
Autori Riconosciuti: | |
Autori: | Castroflorio, T; Falla, D; Wang, K; Svensson, P; Farina, D |
Data di pubblicazione: | 2012 |
Abstract: | This study tested the hypothesis that painful injections of glutamate into the human masseter muscle differentially affect the distribution of the electromyographic (EMG) activity in the masseter muscle at rest and during tooth clenching. Surface EMG signals were recorded bilaterally from the superficial masseter of nine healthy men with a grid of 32 electrodes, before and after intramuscular injection of glutamate or isotonic saline, during rest and isometric contractions at 20%, 40%, 60% and 80% of the maximal voluntary bite force. Intramuscular injection of glutamate evoked moderate pain (0-10 visual analogue scale: 6·4 ± 1·4), with sensory-discriminative characteristics of the perceived pain, evaluated with the use of the McGill Pain Questionnaire (MPQ), similar to those previously reported for patients with temporomandibular disorders. There was no effect of the glutamate injection on EMG amplitude during rest, whereas during tooth clenching, the spatial distribution of the masseter EMG activity on both sides was more uniform in the painful condition compared to the control condition. Moreover, the overall EMG amplitude decreased on both sides during the more forceful tooth clenching following glutamate injection. In conclusion, a unilateral painful stimulation was associated with a bilateral inhibition of the masseter muscles during tooth clenching which resulted in a more uniform distribution of EMG activity. |
Volume: | 39 |
Fascicolo: | 2 |
Pagina iniziale: | 81 |
Pagina finale: | 92 |
Digital Object Identifier (DOI): | 10.1111/j.1365-2842.2011.02246.x |
URL: | https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2842.2011.02246.x |
Parole Chiave: | masseter; experimental pain; high-density surface electromyographic; topographical mapping; Adult; Analysis of Variance; Facial Pain; Glutamic Acid; Humans; Injections, Intramuscular; Isometric Contraction; Male; Masseter Muscle; Nociceptors; Pain Measurement; Bite Force; Electromyography |
Rivista: | JOURNAL OF ORAL REHABILITATION |
Appare nelle tipologie: | 03A-Articolo su Rivista |
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CASTROFLORIO_et_al-2012-Journal_of_Oral_Rehabilitation.pdf | J Oral Rehabil. 2012 Feb;39(2):81-92. doi: 10.1111/j.1365-2842.2011.02246.x. Epub 2011 Aug 18. | PDF EDITORIALE | Utenti riconosciuti Richiedi una copia |