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- Shimada, A., et al.
(författare)
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Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients
- 2016
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Ingår i: European Journal of Pain. - : WILEY-BLACKWELL. - 1090-3801 .- 1532-2149. ; 20:9, s. 1502-1512
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundA randomized, double-blinded, placebo-controlled study was conducted to investigate if single monosodium glutamate (MSG) administration would elevate muscle/serum glutamate concentrations and affect muscle pain sensitivity in myofascial temporomandibular disorders (TMD) patients more than in healthy individuals. MethodsTwelve myofascial TMD patients and 12 sex- and age-matched healthy controls participated in two sessions. Participants drank MSG (150mg/kg) or NaCl (24mg/kg; control) diluted in 400mL of soda. The concentration of glutamate in the masseter muscle, blood plasma and saliva was determined before and after the ingestion of MSG or control. At baseline and every 15min after the ingestion, pain intensity was scored on a 0-10 numeric rating scale. Pressure pain threshold, pressure pain tolerance (PPTol) and autonomic parameters were measured. All participants were asked to report adverse effects after the ingestion. ResultsIn TMD, interstitial glutamate concentration was significantly greater after the MSG ingestion when compared with healthy controls. TMD reported a mean pain intensity of 2.8/10 at baseline, which significantly increased by 40% 30min post MSG ingestion. At baseline, TMD showed lower PPTols in the masseter and trapezius, and higher diastolic blood pressure and heart rate than healthy controls. The MSG ingestion resulted in reports of headache by half of the TMD and healthy controls, respectively. ConclusionThese findings suggest that myofascial TMD patients may be particularly sensitive to the effects of ingested MSG. What does this study add? Elevation of interstitial glutamate concentration in the masseter muscle caused by monosodium glutamate (MSG) ingestion was significantly greater in myofascial myofascial temporomandibular disorders (TMD) patients than healthy individuals. This elevation of interstitial glutamate concentration in the masseter muscle significantly increased the intensity of spontaneous pain in myofascial TMD patients.
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| 2. |
- Ernberg, M., et al.
(författare)
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Experimental myalgia induced by repeated infusion of acidicsaline into the human masseter muscle does not cause the release of algesic substances
- 2013
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Ingår i: European Journal of Pain. - : John Wiley & Sons. - 1090-3801 .- 1532-2149. ; 17:4, s. 539-550
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Animal studies have shown that two repeated intramuscular injections of acidic saline induce mechanical allodynia that lasts for 4 weeks with spread to the contralateral side. In this study, we tested the hypothesis that two repeated intramuscular infusions of acidic saline into the human masseter muscle is associated with pain, mechanical allodynia and release of algesic substances. Eighteen healthy volunteers participated. On day 1, 2.5 mL of acidic saline (pH 3.3) was infused into one of the masseter muscles and isotonic saline (pH 6.0) into the other (randomized and single-blind). Two days later, intramuscular microdialysis was performed to sample serotonin, glutamate, pyruvate, lactate and glucose, during which the saline infusions were repeated. Pain and pressure pain thresholds (PPTs) were recorded before and after infusions on both days.RESULTS:Pain intensity induced by the infusions was higher after acidic than that after isotonic saline (p < 0.05). PPTs were decreased on both sides after microdialysis compared with baseline day 1 (p's < 0.05), but there were no differences in PPTs between sides at any time point. The levels of serotonin, glutamate, pyruvate, lactate or glucose did not change significantly during microdialysis.CONCLUSION:Infusion of acidic saline caused low levels of muscle pain, but no mechanical allodynia and no increased release of algesic substances. The value of this model appears modest, but future studies could be performed with larger sample size and higher flow rate before definite conclusions about the validity of the model for craniofacial myalgia can be drawn.
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| 3. |
- Castrillon, Eduardo E, et al.
(författare)
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Acidic saline-induced pain as a model for experimental masseter myalgia in healthy subjects
- 2013
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Ingår i: European Journal of Pain. - : John Wiley & Sons. - 1090-3801 .- 1532-2149. ; 17:10, s. 1438-1446
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Repeated injection of acidic saline into skeletal muscles of the leg in rodents induces a prolonged bilateral mechanical hyperalgesia that persists for up to 30 days and may be useful to model widespread muscle pain conditions. In this study, repeated injection of acidic (pH 3.3) saline solution into the masseter muscle of healthy human subjects was undertaken to determine if these injections are painful and whether they would induce a prolonged period of muscle sensitization to artificial and/or natural mechanical stimulation of the masseter and temporalis muscles. METHODS: Eighteen subjects (10 male, 8 female) participated in the study. Subjects received two injections of 0.5 mL acidic or regular isotonic saline 2 days apart, in a randomized, double blind, crossover design. RESULTS: There was no significant difference in pain intensity ratings when acidic saline injections were compared with regular saline injections. Pain area drawings were, however, significantly larger in response to the first injection of acidic saline than to the second injection of acidic saline or to either the first or second injection of regular saline. Repeated injection of acidic saline did not significantly alter pressure pain thresholds from the masseter or temporalis muscles on either the injected side or the opposite side over the 10-day post injection monitoring period. There was also no effect of injections on chewing. CONCLUSION: These findings indicate that, unlike in some rodent models, repeated injection of low pH solutions into jaw muscles of humans fails to induce a period of prolonged muscle hyperalgesia.
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| 4. |
- Costa, Yuri M, et al.
(författare)
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Local anaesthesia decreases nerve growth factor induced masseter hyperalgesia
- 2020
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to evaluate the effects of local anaesthesia on nerve growth factor (NGF) induced masseter hyperalgesia. Healthy participants randomly received an injection into the right masseter muscle of either isotonic saline (IS) given as a single injection (n = 15) or an injection of NGF (n = 30) followed by a second injection of lidocaine (NGF + lidocaine; n = 15) or IS (NGF + IS; n = 15) in the same muscle 48 h later. Mechanical sensitivity scores of the right and left masseter, referred sensations and jaw pain intensity and jaw function were assessed at baseline, 48 h after the first injection, 5 min after the second injection and 72 h after the first injection. NGF caused significant jaw pain evoked by chewing at 48 and 72 h after the first injection when compared to the IS group, but without significant differences between the NGF + lidocaine and NGF + IS groups. However, the mechanical sensitivity of the right masseter 5 min after the second injection in the NGF + lidocaine group was significantly lower than the second injection in the NGF + IS and was similar to the IS group. There were no significant differences for the referred sensations. Local anaesthetics may provide relevant information regarding the contribution of peripheral mechanisms in the maintenance of persistent musculoskeletal pain.
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| 8. |
- Exposto, Fernando G, et al.
(författare)
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Remote physical examination for temporomandibular disorders.
- 2022
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Ingår i: Pain. - : Lippincott Williams & Wilkins. - 0304-3959 .- 1872-6623. ; 163:5, s. 936-942
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: There is a need to further develop telemedicine approaches due to the immediate and perhaps long-term consequences of the coronavirus disease 2019. Thus, a remote protocol for assessment of patients with temporomandibular disorders (TMD) was developed, and the agreement of this protocol was compared to the guidelines of the diagnostic criteria for temporomandibular disorders (DC/TMD). A total of 16 individuals were first assessed by a reference standard examination (RSE) and three other examinations applied in a random order by three examiners: standard physical examination (standard examination), physical examination keeping 2 m distance (physical distanced examination) and examination done with the aid of video communication technology (video communication examination). The primary outcomes were the diagnoses of myalgia of the masseter and temporalis muscles, and arthralgia. The diagnoses of intra-articular joint disorders were considered secondary outcomes because of less impact on psychosocial functioning and quality of life when compared with the pain-related diagnoses. The Fleiss kappa coefficient and its 95% confidence interval were computed to determine the level of agreement in diagnoses between each examination protocol and the RSE. There was substantial to almost perfect agreement between the RSE and all the examination protocols for the diagnoses of myalgia (0.86 to 1.00) and arthralgia (0.86 to 0.87) (p<0.001). On the other hand, there was an overall poor agreement (0.30 to 0.58) between the RSE and all the protocols for the diagnosis of disc displacement with reduction. Remote assessment of patients with pain-related TMD is feasible and presents a high degree of accuracy.
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