The impact of stress and anxiety on the pressure pain threshold of myofascial pain patients

The purpose of this study was to evaluate the influence of stress and anxiety on the pressure pain threshold (PPT) of masticatory muscles and on the subjective pain report. Forty-five women, students, with mean age of 19.75 years, were divided into two groups: group 1:29 presenting with masticatory myofascial pain (MFP), according to the Research Diagnostic Criteria for Temporomandibular Disorders and group 2: 16 asymptomatic controls. An electronic algometer registered the pain thresholds on four different occasions throughout the academic year. To measure levels of stress, anxiety and pain, the Beck Anxiety Inventory, Lipp Stress Symptoms Inventory and Visual Analog Scale (VAS) were used. Three-way anova and Tukey`s tests were used to verify differences in PPT between groups, times and sites. Levels of anxiety and VAS were compared using Mann-Whitney test, while Friedman`s test was used for the within-groups comparison at different times (T1 to T4). The chi-squared and Cochran tests were performed to compare groups for the proportion of subjects with stress (alpha = 0.05). Differences in PPT recordings between time (P = 0.001) and sites (P < 0.001) were detected. Higher levels of anxiety and lower PPT figures were detected at T2 (academic examination) (P = 0.001). There was no difference between groups for anxiety and stress at any time (P > 0.05). The MFP group also has shown significant increase of VAS at the time of academic examination (P < 0.001). External stressors such as academic examinations have a potential impact on masticatory muscle tenderness, regardless of the presence of a previous condition such as masticatory myofascial pain.

Influence of the menstrual cycle on the pressure pain threshold of masticatory muscles in patients with masticatory myofascial pain

Objective. The aim of this study was to investigate the influence of the menstrual cycle and oral contraceptive (OC) intake on the pressure pain threshold (PPT) of masticatory muscles in patients with masticatory myofascial pain (MFP). Study design. The sample was composed of 36 women, divided into 4 groups, according to the presence of MFP and the intake of OC (15 patients had MFP [7 taking OC] and 21 were pain-free controls [8 taking OC]). The algometer-based PPT of masseter and temporalis, and the record of subjective pain by visual analog scale (VAS) were determined during 2 consecutives menstrual cycles at 4 phases (menstrual, follicular, periovulatory, and luteal). A 3-way ANOVA for repeated measurements, Kruskal-Wallis, Friedman, and Dunn tests, with a 5% significant level analyzed the data. Results. PPT was significantly lower in MFP patients when compared with controls throughout the experiment (P < .001). The menstrual phases did not influence PPT (P > .05), while the intake of OC seems to raise PPT levels for the left temporalis (P = .01) and right masseter (P = .04). VAS was, in general, higher at the menstrual phase Conclusions. Different phases of the menstrual cycle have no influence on PPT values, regardless of the presence of a previous condition, as masticatory myofascial pain, while the intake of OC is associated with decreased levels of reported pain.

Palpation of the lateral pterygoid area in the myofascial pain diagnosis

Objectives. To evaluate the diagnostic value of intraoral palpation at the lateral pterygoid (LP) area as part of the physical examination to detect myofascial pain, according to modified research diagnostic criteria for temporomandibular disorders. Study design. Fouty-four women composed the myofascial pain group, and 33 symptom-free age-matched were the control group. One examiner calibrated and blinded to group distribution performed 2 intraoral bilateral palpations of the lateral pterygoid. Results. The LP area palpation showed sensitivity and specificity values of 79.55% and 77.27%, respectively, and positive and negative likelihood ratios of 3.50 and 0.26, respectively. Conclusions. Palpation at the LP area did not reach acceptable values of specificity, and care must be taken when judging positive response to this procedure.

Evaluation of Low Intensity Laser Therapy In Myofascial Pain Syndrome

Limited studies have demonstrated that low intensity laser therapy (LILT) may have a therapeutic effect on the treatment of myofascial pain syndrome (MPS). Sixty (60) patients with MPS and having one active trigger point in the anterior masseter and anterior temporal muscles were selected and assigned randomly to six groups (n=10): Groups I to III were treated with GaAIAS (780 nm) laser, applied in continuous mode and in a meticulous way, twice a week, for four weeks. Energy was set to 25 J/cm(2), 60 J/cm2 and 105 J/cm2, respectively. Groups IV to VI were treated with placebo applications, simulating the same parameters as the treated groups. Pain scores were assessed just before, then immediately after the fourth application, immediately after the eighth application, at 15 days and one month following treatment. A significant pain reduction was observed over time (p<0.001). The analgesic effect of the LILT was similar to the placebo groups. Using the parameters described in this experiment, LILT was effective in reducing pain experienced by patients with myofascial pain syndrome. Thus, it was not possible to establish a treatment protocol. Analyzing the analgesic effect of LILT suggests it as a possible treatment of MPS and may help to establish a clinical protocol for this therapeutic modality.

Association between rhythmic masticatory muscle activity during sleep and masticatory myofascial pain: A polysomnographic study

Aims: To test for an association between rhythmic masticatory muscle activity during sleep, as assessed according to polysomnographic criteria for sleep bruxism (RMMA-SB), and myofascial pain (MFP), as well as the chance of occurrence of MFP in patients with RMMA-SB. Methods: Thirty MFP patients (diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders) and 30 age- and gender-matcbed asymptomatic controls underwent a polysomnographic examination. Also, any self-reporting of daytime clenching (DC) was registered in 58 of these subjects. Results: Most MFP patients reported mild or moderate pain (46.67% and 43.33%, respectively), and only 3 (10%) reported severe pain. Pain duration ranged from 2 to 120 months (mean 34.67 +/- 36.96 months). Significant associations were observed between RMMA-SB and MFP as well as between DC and MFP. Conclusions: (1) RMMA-SB is significantly associated with MFP; (2) although RMMA-SB represents a risk factor for MFP, this risk is low; and (3) DC probably constitutes a stronger risk factor for MFP than RMMA-SB.

Effect of experimental chewing on masticatory muscle pain onset

OBJECTIVES: To evaluate the effect of a chewing exercise on pain intensity and pressure-pain threshold in patients with myofascial pain. METHODS: Twenty-nine consecutive women diagnosed with myofascial pain (MFP) according to the Research Diagnostic Criteria comprised the experimental group and 15 healthy age-matched female were used as controls. Subjects were asked to chew a gum stick for 9 min and to stay at rest for another 9 min afterwards. Pain intensity was rated on a visual analog scale (VAS) every 3 min. At 0, 9 and 18 min, the pressure-pain threshold (PPT) was measured bilaterally on the masseter and the anterior, medium, and posterior temporalis muscles. RESULTS: Patients with myofascial pain reported increase (76%) and no change (24%) on the pain intensity measured with the VAS. A reduction of the PPT at all muscular sites after the exercise and a non-significant recovery after rest were also observed. CONCLUSION: The following conclusions can be drawn: 1. there are at least two subtypes of patients with myofascial pain that respond differently to experimental chewing; 2. the chewing protocol had an adequate discriminative ability in distinguishing patients with myofascial pain from healthy controls.

Myofascial trigger point: A possible way of modulating tinnitus

In order to investigate whether myofascial trigger points can modulate tinnitus, as well as the association between tinnitus and myofascial trigger points, 94 individuals with and 94 without tinnitus, matched by age and gender, were analyzed by means of bilateral digital pressure of 9 muscles. Temporary modulation of tinnitus was frequently observed (55.9%) during digital pressure, mainly in the masseter. The rate of tinnitus modulation was significantly higher on the same side of the myofascial trigger point subject to examination in 6 out of 9 muscles. An association between tinnitus and the presence of myofascial trigger points was observed (p < 0.001), as well as a laterality association between the ear with the worst tinnitus and the side of the body with more myofascial trigger points (p < 0.001). Thus, this relationship could be explained not only by somatosensory-auditory system interactions but also by the influence of the sympathetic system. Copyright (c) 2007 S. Karger AG, Basel.

Low Level Laser Effects On Pain to Palpation and Electromyographic Activity in TMD Patients: A Double-Blind, Randomized, Placebo-Controlled Study

The purpose of this study was to evaluate the effect of diode laser (GaAlAs - 780 nm) on pain to palpation and electromyographic (EMG) activity of the masseter and anterior temporalis muscles. The laser was applied on the temporalis and masseter muscles twice a week (four weeks). Forty-eight (48) patients with myofascial pain were randomly assigned between actual and placebo treatments and between the energetic doses of 25 J/cm(2) and 60 J/cm(2), and were evaluated using VAS before, immediately after the final application, and 30 days after the laser treatment. Surface electromyography was performed with maximum dental clenching before and after laser therapy. The results show there were no significant statistical differences in the EMG activity between the groups before and after laser treatment. With regard to the pain at palpation, although both groups presented a significant difference in the symptoms before and after the treatment, only the active doses showed statistically significant reductions in pain level in all the regions of the palpated muscles. However, there was no significant statistical difference between groups (experimental and placebo). In conclusion, low level laser did not promote any changes in EMG activity. The treatment did, however, lessen the pain symptoms in the experimental groups.

Acupuncture and Temporomandibular Disorders: A 3-Month Follow-up EMG Study

Objectives: The purpose of this study was to investigate the levels of electromyographic (EMG) activation and maximal molar bite force before and after a 3-month acupuncture therapy in individuals with temporomandibular disorder (Helkimo Index) from a pool of subjects attending the Special Care Course of the Ribeirao Preto Dental School, Sao Paulo University, Brazil. Design: All 17 patients, aged between 37 and 50 years (44.2 +/- 4.84 years), with an average weight of 71 +/- 9.45 kg and height of 1.64 +/- 0.07 m, were clinically examined with regard to pain and dysfunctions of the masticatory system. The temporomandibular acupuncture points of needling were IG4, E6, E7, B2, VB14, VB20, ID18, ID19, F3, E36, VB34, E44, R3, and HN3. EMG measures were acquired before and after the treatment using a MyoSystem-BR1 electromyographer. The data collected at rest, protrusion, left and right laterality, and clenching were normalized by maximum voluntary contraction. Maximal bite force in right and left molar regions were registered using a dynamometer with a capacity of up to 1000 N, adapted for oral conditions. The highest value out of three recordings was considered to be the individual's maximal bite force. The results were statistically analyzed using the paired t test (SPSS version 15.0) during the comparison before and after treatment. Results: We found decreased EMG activity at rest, protrusion, left and right laterality, and clenching; as well as increased values of maximal bite force after acupuncture treatment. Conclusions: Acupuncture promoted alterations in the EMG activity of masticatory muscles, increased maximal molar bite force, and led to remission of the subjects' painful symptomatology.

Treatment of obstructive sleep apnea syndrome in patients from a teaching hospital in Brazil: is it possible?

The aim of this study was to evaluate the efficacy of a cost-effective intra-oral appliance for obstructive sleep apnea syndrome built into a large teaching hospital. Out of 20 evaluated and treated patients, 14 concluded the study: eight men and six women, with a mean age of 42-46 (mean + SD) years and mean body mass index of 27.66. Inclusion criteria were mild or moderate apnea-hypopnea index (AHI) according to a polysomnographic study. All patients were treated with the monobloco intra-oral appliance. They were then submitted to a follow-up polysomnographic study after 60 days using the appliance. An orofacial clinical evaluation was carried out with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire and with clinical evaluation questionnaire devised by the Orofacial Pain Team before and 60 days after fitting the intra-oral appliance. The AHI showed a statistically meaningful (p = 0.002) reduction from 15.53 to 7.82 events per hour, a non-statistically significant oxygen saturation increase from 83.36 to 84.86 (p = 0.09), and Epworth`s sleepiness scale reduction from 9.14 to 6.36 (p = 0.001). Three patients did not show any improvement. The most common side effect during the use of the appliance/device was pain and facial discomfort (28.57%), without myofascial or temporomandibular joint pain as evaluated by the RDC/TMD questionnaire. The intra-oral device produced a significant reduction of the apnea-hypopnea index during the study period with the use of the monobloco intra-oral appliance. Patients did not show prior myofascial pain or 60 days after use of the intra-oral appliance.

Migraine is the Most Prevalent Primary Headache in Individuals with Temporomandibular Disorders

Aims: To assess the prevalence of primary headaches (HA) in adults with temporomandibular disorders (TMD) who were assessed in a specialty orofacial pain clinic, as well as in controls without TMD. Methods: The sample consisted of 158 individuals with TMD seen at a university-based specialty clinic, as well as 68 controls. The Research Diagnostic Criteria for TMD were used to diagnose the TMD patients. HAs were assessed using a structured interview and classified according to the Second Edition of the International Classification for Headache Disorders. Data were analyzed by chi-square tests with a significance level of 5% and odds ratio (OR) tests with a 95% confidence interval (CI). Results: HAs occurred in 45.6% of the control group (30.9% had migraine and 14.7% had tension-type headache [TTH]) and in 85.5% of individuals with TMD. Among individuals with TMD, migraine was the most prevalent primary HA (55.3%), followed by TTH (30.2%); 14.5% had no HA. In contrast to controls, the odds ratio (OR) for HA in those with TMD was 7.05 (95% confidence interval [CI] = 3.65-13.61; P = .000), for migraine, the OR was 2.76 (95% CI = 1.50-5.06; P = .001), and for TTH, the OR was 2.51 (95% CI = 1.18-5.35; P = .014). Myofascial pain/arthralgia was the most common TMD diagnosis (53.2%). The presence of HA or specific HAs was not associated with the time since the onset of TMD (P = .714). However, migraine frequency was positively associated with TMD pain severity (P = .000). Conclusion: TMD was associated with increased primary HA prevalence rates. Migraine was the most common primary HA diagnosis in individuals with TMD. J OROFAC PAIN 2010;24:287-292

Trigeminal pain and quantitative sensory testing in painful peripheral diabetic neuropathy

Objective: To evaluate patients with Diabetes Mellitus type 2 and painful peripheral neuropathy in order to investigate oral complaints and facial somatosensory findings. Research design and methods: Case-control study; 29 patients (12 women, mean age 57.86 yo) with Diabetes Mellitus type 2 and 31 age-gender-matched controls were evaluated with a standardized protocol for general characteristics, orofacial pain, research diagnostic criteria for temporomandibular disorders, visual analogue scale and McGill Pain questionnaire, and a systematic protocol of quantitative sensory testing for bilateral facial sensitivity at the areas innervated by the trigeminal branches, which included the thermal detection by ThermoSensi 2, tactile evaluation with vonFrey filaments, and superficial pain thresholds with a superficial algometer (Micromar). Statistical analysis was performed with Wilcoxon, chi-square, confidence intervals and Spearman (p < 0.05). Results: Orofacial pain was reported by 55.2% of patients, and the most common descriptor was fatigue (50%); 17.2% had burning mouth. Myofascial temporomandibular disorders were diagnosed in 9(31%) patients. The study group showed higher sensory thresholds of pain at the right maxillary branch (p = 0.017) but sensorial differences were not associated with pain (p = 0.608). Glycemia and HbA(1c) were positively correlated with the quantitative sensory testing results of pain (p < 0.05) and cold (p = 0.044) perceptions. Higher pain thresholds were correlated with higher glycemia and glycated hemoglobin (p = 0.027 and p = 0.026). Conclusions: There was a high prevalence of orofacial pain and burning mouth was the most common complaint. The association of loss of pain sensation and higher glycemia and glycated hemoglobin can be of clinical use for the follow-up of DM complications. (C) 2010 Elsevier Ltd. All rights reserved.

Diagnostic and clinical factors associated with pulpal and periapical pain

A retrospective survey was designed to identify diagnostic subgroups and clinical factors associated with odontogenic pain and discomfort in dental urgency patients. A consecutive sample of 1,765 patients seeking treatment for dental pain at the Urgency Service of the Dental School of the Federal University of Goiás, Brazil, was selected. Inclusion criteria were pulpal or periapical pain that occurred before dental treatment (minimum 6 months after the last dental appointment), and the exclusion criteria were teeth with odontogenic developmental anomalies and missing information or incomplete records. Clinical and radiographic examinations were performed to assess clinical presentation of pain complaints including origin, duration, frequency and location of pain, palpation, percussion and vitality tests, radiographic features, endodontic diagnosis and characteristics of teeth. Chi-square test and multiple logistic regression were used to analyze association between pulpal and periapical pain and independent variables. The most frequent endodontic diagnosis of pulpal pain were symptomatic pulpitis (28.3%) and hyperreactive pulpalgia (14.4%), and the most frequent periapical pain was symptomatic apical periodontitis of infectious origin (26.4%). Regression analysis revealed that closed pulp chamber and caries were highly associated with pulpal pain and, conversely, open pulp chamber was associated with periapical pain (p<0.001). Endodontic diagnosis and local factors associated with pulpal and periapical pain suggest that the important clinical factor of pulpal pain was closed pulp chamber and caries, and of periapical pain was open pulp chamber.

Measurements of jaw movements and TMJ pain intensity in patients treated with GaAlAs laser

The aim of this study was to evaluate the effectiveness of low-level laser therapy (LLLT) on the improvement of the mandibular movements and painful symptoms in individuals with temporomandibular disorders (TMD). Forty patients were randomly divided into two groups (n=20): Group 1 received the effective dose (GaAlAs laser ? 830 nm, 40 mW, 5J/cm2) and Group 2 received the placebo application (0 J/cm2), in continuous mode on the affected condyle lateral pole: superior, anterior, posterior, and posterior-inferior, twice a week during 4 weeks. Four evaluations were performed: E1 (before laser application), E2 (right after the last application), E3 (one week after the last application) and E4 (30 days after the last application). The Kruskal-Wallis test showed significant more improvements (p<0.01) in painful symptoms in the treated group than in the placebo group. A significant improvement in the range of mandibular movements was observed when the results were compared between the groups at E4. Laser application can be a supportive therapy in the treatment of TMD, since it resulted in the immediate decrease of painful symptoms and increased range of mandibular movements in the treated group. The same results were not observed in the placebo group.

Participation of neuronal nitric oxide synthase in experimental neuropathic pain induced by sciatic nerve transection

Nerve injury leads to a neuropathic pain state that results from central sensitization. This phenomenom is mediated by NMDA receptors and may involve the production of nitric oxide (NO). In this study, we investigated the expression of the neuronal isoform of NO synthase (nNOS) in the spinal cord of 3-month-old male, Wistar rats after sciatic nerve transection (SNT). Our attention was focused on the dorsal part of L3-L5 segments receiving sensory inputs from the sciatic nerve. SNT resulted in the development of neuropathic pain symptoms confirmed by evaluating mechanical hyperalgesia (Randall and Selitto test) and allodynia (von Frey hair test). Control animals did not present any alteration (sham-animals). The selective inhibitor of nNOS, 7-nitroindazole (0.2 and 2 µg in 50 µL), blocked hyperalgesia and allodynia induced by SNT. Immunohistochemical analysis showed that nNOS was increased (48% by day 30) in the lumbar spinal cord after SNT. This increase was observed near the central canal (Rexed’s lamina X) and also in lamina I-IV of the dorsal horn. Real-time PCR results indicated an increase of nNOS mRNA detected from 1 to 30 days after SNT, with the highest increase observed 1 day after injury (1469%). Immunoblotting confirmed the increase of nNOS in the spinal cord between 1 and 15 days post-lesion (20%), reaching the greatest increase (60%) 30 days after surgery. The present findings demonstrate an increase of nNOS after peripheral nerve injury that may contribute to the increase of NO production observed after peripheral neuropathy.