Myofascial Temporomandibular Disorder Research Articles

The Role of Peripheral Glutamate and Glutamate Receptors in Muscle Pain

Objectives: To review evidence that associates elevated muscle interstitial glutamate concentration and the activation of peripheral glutamate receptors with the development and maintenance of muscle pain in conditions such as myofascial temporomandibular disorders [TMDs].Findings: In certain noninflammatory musculoskeletal pain conditions, an association between pain, elevated glutamate concentrations and the expression of peripheral N-methyl-d-aspartate receptors [NRs] has been made. Myofascial TMDs are a noninflammatory muscle pain disorder characterized by pain and localized mechanical sensitivity in the masticatory muscle and a greater prevalence in young women than in men. Artificial elevation of glutamate concentrations in the masticatory muscles of healthy subjects evokes intense, short duration pain that is significantly greater in woman than in men and induces a more prolonged, localized mechanical sensitization that is similar in both sexes. Glutamate-evoked pain and sensitization may be attenu...

Muscle pain in the head: overlap between temporomandibular disorders and tension-type headaches

A variety of painful problems can affect the muscles in the head and face. Both temporomandibular disorders and tension-type headaches are believed to have a significant contribution from the skeletal muscles and have several clinical features in common. It still unclear, however, to what extent these two prevalent disorders are separate entities or have similar pathophysiological background. There is now reasonably good evidence that myofascial temporomandibular disorder patients are more likely to have a tension-type headache problem and vice versa, but the overlap is not complete. Studies have documented similarities regarding sensitization of the nociceptive pathways, dysfunction of the endogenous pain modulatory systems as well as contributing genetic factors, but there are also a number of distinct differences between temporomandibular disorders and tension-type headaches that need to be considered. Using the current classification systems, myofascial temporomandibular disorder pain and tension-type headache disorders do overlap and appear to share many of the same pathophysiological mechanisms, but it would be premature to consider them as identical entities since the importance of, for example, the affected muscles and associated function and genetic background needs to be established. Orofacial pain and headache specialists should collaborate to further develop diagnostic procedures and management strategies of temporomandibular disorders and tension-type headaches.

Nonpharmacologic approaches to the management of myofascial temporomandibular disorders.

The temporomandibular disorders (TMDs) are a heterogeneous group of painful musculoskeletal conditions that include masticatory muscle pain. TMD is a common condition but its etiology is, as yet, poorly understood. Although TMD can be quite disabling, most patients presenting with symptoms improve regardless of treatment type. This article focuses on nonpharmacologic treatments for TMD; recent articles on etiology, assessment, and treatment for this muscle pain condition are reviewed. Psychological approaches include biofeedback, minimal therapist contact interventions, relaxation, and cognitive-behavioral therapy. We suggest that treatments based on the biopsychosocial model of illness should be used concurrently with treatments focusing only on the biomedical aspects of TMD. Psychological treatments need not be viewed as a treatment of last resort, but rather should be delivered concurrent with biomedical treatments. We present data from recent clinical trials showing that treatment-matching approaches tailoring psychological and educational treatments to psychosocial profiles, delivered concurrent with usual dental care, results in greater and more sustained improvement than usual dental care alone. As such, treatment for TMD should be viewed in much the same way as treatment for most other chronic pain conditions, that is, from a multidisciplinary perspective.

Analysis of stimulus-evoked pain in patients with myofascial temporomandibular pain disorders

The pathophysiological mechanisms of myofascial temporomandibular disorders (TMD) are still under investigation. The hypothesis that TMD pain is caused by a generalized sensitization of higher order neurons in the nociceptive pathways combined with a decreased efficacy of endogenous inhibitory systems has recently gained support in the literature. This study was designed to further investigate the somatosensory sensibility within and outside the craniofacial region. Twenty-two patients fulfilled the research diagnostic criteria for TMD for myofascial pain (Dworkin and LeResche, J Craniomandib Disord Facial Oral Pain 6 (1992) 301) and 21 age- and sex-matched subjects served as a control group. The somatosensory sensibility to a deep tonic input was tested by standardized infusions of hypertonic saline into the masseter and anterior tibialis muscle. Furthermore, pressure pain thresholds (PPTs) and heat pain thresholds (HPTs) were assessed with phasic stimuli at the same sites before and following the infusions. Myofascial TMD patients reported infusion of hypertonic saline to be more painful on 10 cm visual analogue scales (peak pain 8.8±0.4 cm) than control subjects (6.8±0.5 cm, t-test: P=0.003) in the masseter but not in the anterior tibialis (7.4±0.5 vs. 6.6±0.5 cm, P=0.181). The perceived area of experimental masseter pain measured on drawings was marginally larger in TMD patients (2.6±0.5 arbitrary units (a.u.)) than in control subjects (1.4±0.2 a.u., Mann–Whitney: P=0.048) but no differences were observed for the anterior tibialis (P=0.771). The PPTs were lower in the myofascial TMD patients compared to the control group, both in the masseter (analysis of variance (ANOVA): P=0.002) and in the anterior tibialis (P=0.005), whereas there were no significant differences in HPT (ANOVAs: P=0.357, P=0.101). There were no significant correlations between measures of somatosensory sensibility and measures of clinical pain intensity, pain duration, graded chronic pain scores or somatization or depression scores (Pearson: R<0.304, P>0.172). The present study in a well-defined group of myofascial TMD patients found that the responsiveness to both tonic and phasic deep stimuli, but not to phasic superficial inputs at the pain threshold level, in the craniofacial region was higher compared with a control group. These findings suggest that myofascial TMD pain is associated with a facilitation of stimulus-evoked pain primarily, but not exclusively related to the painful region.

Fibromyalgia, chronic fatigue syndrome, and myofascial pain syndrome.

Fibromyalgia and widespread pain were common in Gulf War veterans with unexplained illness referred to a rheumatology clinic. Increased tenderness was demonstrated in the postmenstrual phase of the cycle compared with the intermenstrual phase in normally cycling women but not in users of oral contraceptives. Patients with fibromyalgia had high levels of symptoms that have been used to define silicone implant-associated syndrome. Tender points were found to be a common transient finding associated with acute infectious mononucleosis, but fibromyalgia was an unusual long-term outcome. The common association of fibromyalgia with other rheumatic and systemic illnesses was further explored. A preliminary study revealed a possible linkage of fibromyalgia to the HLA region. Patients with fibromyalgia were found to have an impaired ability to activate the hypothalamic pituitary portion of the hypothalamic pituitary adrenal axis as well as the sympathoadrenal system, leading to reduced corticotropin and epinephrine response to hypoglycemia. Much interest has been expressed in the literature on the possible role of autonomic dysfunction in the development or exacerbation of fatigue and other symptoms in chronic fatigue syndrome. Mycoplasma genus and mycoplasma fermentans were detected by polymerase chain reaction in patients with chronic fatigue syndrome. It was reported that myofascial temporomandibular disorder does not run in families. No major therapeutic trials in fibromyalgia, chronic fatigue syndrome, or myofascial pain syndrome were reported over the past year. The effectiveness of cognitive behavioral therapy and behavior therapy for chronic pain in adults was emphasized. A favorable outcome of fibromyalgia and chronic fatigue syndrome in children and adolescents was reported.

Myofascial TMD does not run in families

This study tests whether facial pain or associated symptoms and disorders aggregates in first degree relatives of those with myofascial temporomandibular disorders (M/TMD). We randomly selected one first degree relative of 106 probands with a lifetime history of M/TMD and one first degree relative of 118 acquaintance control probands with no history of M/TMD. Relatives were directly interviewed about the lifetime occurrence of a broad range of painful and non-painful health conditions and symptoms. Analyses revealed that rates of facial pain, symptoms of TMDs, and a range of other musculoskeletal conditions were not significantly different in first degree relatives of M/TMD probands and first degree relatives of controls. In addition, proband descriptors of facial pain severity or disability did not significantly predict the likelihood of having a first degree relative with one or more TMD-related symptoms. These results indicate that M/TMD is not a familial disorder.

Adaptive psychophysical methodology applied to sensory-discriminative tests of pain perception

Compare pain-related measures and psychosocial variables between glutamate-evoked jaw muscle pain in healthy subjects (HS) and patients with persistent myofascial temporomandibular disorder (TMD) pain.Forty-seven female HS and 10 female patients with persistent myofascial TMD pain participated. The HS received an injection of glutamate into the masseter muscle to model persistent myofascial TMD pain. Participants filled out a coping strategies questionnaire (CSQ), the symptom checklist 90 (SCL-90) and McGill pain questionnaire (MPQ). Pain intensity was assessed on an electronic visual analogue scale (VAS). Pain-drawing areas, numerical rating scale (NRS) scores of unpleasantness, pressure pain thresholds (PPTs) and pressure pain tolerance (PPTOL) were measured. Unpaired t-tests and correlation tests were used for analyses.The groups were significantly different when comparing the CSQ scores of control, decrease, diverting attention, increase of behavioural activities and somatization. The peak VAS pain, NRS of unpleasantness and MPQ scores were not significantly different between groups, but PPT and PPTOL were significantly lower in the TMD patients. Significant positive correlations were found in the TMD patients between peak VAS pain and CSQ catastrophizing score and SCL-90 somatization. The scores of PPTs and PPTOLs, in patients showed positive correlations with CSQ reinterpreting pain sensations scores and PPTs correlated with CSQ praying/hoping scores.Glutamate-evoked pain responses in HS and persistent myofascial TMD pain have similar sensory-discriminative and affective-unpleasantness components but differ in psychosocial features. This study suggests that experimental designs based on glutamate injection into muscle can provide an appropriate model for elucidating persistent myofascial pain conditions.

Study of expepjivo tal pain measures and nociceptive reflex in chronic pain patients

Compare pain-related measures and psychosocial variables between glutamate-evoked jaw muscle pain in healthy subjects (HS) and patients with persistent myofascial temporomandibular disorder (TMD) pain.Forty-seven female HS and 10 female patients with persistent myofascial TMD pain participated. The HS received an injection of glutamate into the masseter muscle to model persistent myofascial TMD pain. Participants filled out a coping strategies questionnaire (CSQ), the symptom checklist 90 (SCL-90) and McGill pain questionnaire (MPQ). Pain intensity was assessed on an electronic visual analogue scale (VAS). Pain-drawing areas, numerical rating scale (NRS) scores of unpleasantness, pressure pain thresholds (PPTs) and pressure pain tolerance (PPTOL) were measured. Unpaired t-tests and correlation tests were used for analyses.The groups were significantly different when comparing the CSQ scores of control, decrease, diverting attention, increase of behavioural activities and somatization. The peak VAS pain, NRS of unpleasantness and MPQ scores were not significantly different between groups, but PPT and PPTOL were significantly lower in the TMD patients. Significant positive correlations were found in the TMD patients between peak VAS pain and CSQ catastrophizing score and SCL-90 somatization. The scores of PPTs and PPTOLs, in patients showed positive correlations with CSQ reinterpreting pain sensations scores and PPTs correlated with CSQ praying/hoping scores.Glutamate-evoked pain responses in HS and persistent myofascial TMD pain have similar sensory-discriminative and affective-unpleasantness components but differ in psychosocial features. This study suggests that experimental designs based on glutamate injection into muscle can provide an appropriate model for elucidating persistent myofascial pain conditions.