Journal of Oral & Facial Pain and Headache

The recently published Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I, which is recommended for use in clinical and research settings, has provided an update of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The authors of the DC/TMD based their publication on the results of a Validation Project (2001-2008) and consecutive workgroup sessions held between 2008 and 2013. The DC/TMD represents a major change in both content and procedures; nonetheless, earlier concerns and new insights have only partly been followed up when drafting the new recommendations. Moreover, the emphasis on immediate implementation in clinical and research settings is not in line with the provided external evidence on which the DC/TMD is based. This Focus Article describes these concerns with regard to several aspects of the DC/TMD: the additional classification categories; the high dependency on pressure-pain results from use of the recommended palpation technique; the TMD pain screening instrument; the test population characteristics; the utility of additional subgroups; the use of a reference standard; the dichotomy between pain and dysfunction; and the DC/TMD algorithms. Thus, although the DC/TMD represents an improvement over the RDC/TMD, its immediate implementation in research and clinical care does not yet appear to be adequately substantiated. Keywords: classification, diagnosis, facial pain, reference standards, temporomandibular disorders

Aims: To determine if the effects of experimental temporalis muscle pain on jaw muscle activity vary with the jaw task performed, jaw displacement magnitude, participant being studied, and with psychological measures. Methods: Jaw movement was tracked, and electromyographic (EMG) activity was recorded from the masseter and anterior temporalis and digastric muscles in 14 asymptomatic participants during standardized opening/closing jaw movement, free chewing, and standardized chewing tasks. Tasks were repeated in three blocks: Block 1 (baseline), Block 2 (during 5% hypertonic or 0.9% isotonic saline infusion into the anterior temporalis), and Block 3 (during infusion of the opposite solution). Participants also completed the Depression, Anxiety, and Stress Scales 21 (DASS 21), the Fear of Pain Questionnaire (FPQ III), the Pain Self-Efficacy Questionnaire (PSEQ), and the Pain Catastrophizing Scale (PCS). Analyses involved linear mixedmodel analysis and Pearson correlations. P .05 was considered statistically significant. Results: The presence of a significant difference in jaw muscle EMG activity between hypertonic and isotonic saline infusions varied between tasks and between jaw muscle agonists and antagonists, but not in displacement magnitude. There were qualitative differences between participants in the effects of infusion on EMG activity. During hypertonic saline infusion, significant positive correlations were noted between jaw-closing EMG activity and anxiety, fear of medical pain, and PCS scores. Conclusion: Noxious stimulation of the temporalis muscle results in changes in jaw muscle activity, which can vary with the task, the muscle, the participant, and some psychological variables. Keywords: electromyography, jaw, mastication, masticatory muscles, pain, psychological scales

Aims: To determine the efficacy of occipital nerve stimulation (ONS) in reducing the intensity, duration, and frequency of medically intractable primary headaches. Methods: A systematic review was carried out by searching three electronic databases: the Cochrane Library, MEDLINE via PubMed, and Web of Science. Randomized controlled trials (RCTs) and case series were eligible for inclusion. RCTs were assessed for quality of evidence by using the Cochrane Risk of Bias and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tools. Descriptive statistics of reported outcomes in eligible studies are presented in tabular form. Meta-analyses of RCTs comparing ONS therapy to sham therapy in chronic migraine patients were conducted for the outcomes responder rate, headache frequency, and headache intensity. Results: Four RCTs, 1 follow-up study, and 19 case series met the inclusion criteria. The quality of the evidence was low, with all four RCTs assessed as having a high risk of bias and small sample size. Meta-analyses of three RCTs showed patients receiving ONS therapy had a significant reduction of 3 headache days per month (difference in means = -3.061; 95% confidence interval [CI] = -5.162 to -0.961; P = .004) and a significant reduction in Migraine Disability Assessment score (standardized difference in means [SDM] = -0.634; 95% CI = -0.933 to -0.335; P .001) compared to sham (subthreshold) therapy. There were no statistically significant differences in reduction in pain intensity (SDM = -1.220; 95% CI = -2.489 to -0.049; P = .060) or in the number of responders (risk ratio [RR] = 1.581; 95% CI = 0.749 to 3.355; P = .229). Conclusion: ONS may be effective when compared to sham therapy, but the small number of RCTs and the heterogeneity of outcomes suggest further research in this field is needed. Keywords: chronic migraine, cluster headache, meta-analyses, occipital nerve stimulation, primary headache disorders

Aims: To assess the effectiveness of intra-articular injections of sodium hyaluronate (NaH) or corticosteroids (CS) for treatment of intracapsular temporomandibular disorders (TMD). Methods: Single- or double-blinded randomized controlled trials (RCTs) on the effectiveness of NaH or CS injections, compared to each other or to placebo, for the treatment of intracapsular TMD due to osteoarthritis and/or internal joint derangement were analyzed in this systematic review and meta-analysis. Electronic searches of MEDLINE through the PubMed, Web of Science, and Cochrane Library databases were conducted on March 17, 2015, and an updated search was conducted on June 7, 2017. Three reviewers independently extracted the data and assessed the risk of bias of included studies. Results: An initial search yielded 245 studies, and 5 additional studies were identified through cross referencing. A total of 22 studies were identified as relevant based on the abstracts, but only 7 RCTs met the inclusion criteria. Six of the included studies had unclear risk of bias, and one had high risk of bias. Four studies were eligible for meta-analysis. Pooled results showed no significant difference in short- or long-term pain improvement with NaH compared to CS. The number of responders to NaH was significantly more than placebo in one study, but not significantly higher than CS in another study. Conclusion: Although there was no significant difference between the effectiveness of NaH and CS intra-articular injections, there was some evidence that NaH was better than placebo. Further research is needed to determine the minimum effective dose and long-term side effects of both injections. Keywords: corticosteroid, hyaluronic acid, intra-articular injection, sodium hyaluronate, temporomandibular disorders

Aims: To identify structural changes in gray matter in suspected migraine generators (the hypothalamus and/or brainstem nuclei) and pain pathways and to evaluate whether structural changes in migraine are definitive or resolve with age. Methods: Voxel-based morphometry (VBM) was used to assess differences in gray matter between 39 healthy controls (HC), 25 episodic migraine (EM) subjects, and 37 subjects with a history of migraine (HM). In addition, morphometric changes were specifically investigated in suspected migraine generators and/ or pain pathways. For statistical analyses, t tests between the groups were performed, and a correction for multiple comparisons was used. Results: Wholebrain analysis did not reveal any gray or white matter changes. However, when the analysis was limited to the pain matrix, a lower gray matter volume was observed in the left second somatosensory (SII) cortex in EM subjects compared to HC subjects. This volume was significantly reduced in the EM group compared to the HC group and to the HM group, but not in the HM group compared to the HC group. Conclusion: Morphometric abnormalities in the SII in subjects with ongoing migraine but not in subjects with a resolved migrainous disease are likely to characterize a migrainous state rather than be a marker of brain susceptibility to migraine. Keywords: brain morphology, elderly, migraine, past migraine

Aims: To determine the involvement of tumor necrosis factor alpha (TNFα) signaling in the trigeminal ganglion (TG) in the mechanical hypersensitivity of the masseter muscle during temporomandibular joint (TMJ) inflammation. Methods: A total of 55 male Sprague-Dawley rats were used. Following injection of Complete Freund's Adjuvant into the TMJ, the mechanical sensitivities of the masseter muscle and the overlying facial skin were measured. Satellite glial cell (SGC) activation and TNFα expression in the TG were investigated immunohistochemically, and the effects of their inhibition on the mechanical hypersensitivity of the masseter muscle were also examined. Student t test or two-way repeated-measures analysis of variance followed by Bonferroni multiple comparisons test were used for statistical analyses. P .05 was considered to reflect statistical significance. Results: Mechanical allodynia in the masseter muscle was induced without any inflammatory cell infiltration in the muscle after TMJ inflammation. SGC activation and an increased number of TNFα-immunoreactive cells were induced in the TG following TMJ inflammation. Intra-TG administration of an inhibitor of SGC activity or of TNFα- neutralizing antibody depressed both the increased number of TG cells encircled by activated SGCs and the mechanical hypersensitivity of the masseter following TMJ inflammation. Conclusion: These findings suggest that persistent masseter hypersensitivity associated with TMJ inflammation was mediated by SGC-TG neuron interactions via TNFα signaling in the TG. Keywords: extraterritorial pain, satellite glial cell, temporomandibular joint, trigeminal ganglion, tumor necrosis factor alpha

Aims: To determine the effect of amyotrophic lateral sclerosis (ALS) on aspects of masticatory function and to assess the relationship between ALS and the prevalence of traumatic mucosal lesions caused by oral self-injury. Methods: A total of 153 ALS patients and 23 control subjects participated in this crosssectional study. Clinical characteristics including site of onset, medication, type of feeding, and use of noninvasive mechanical ventilation were recorded. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocol and a specific questionnaire to assess aspects of masticatory dysfunction and frequency of self-injury of the oral mucosa were applied to all participants. Maximum mandibular range of motion, maximum bite force, and maximum fingerthumb grip force were determined and tested with Mann Whitney, Kruskal-Wallis, or chi-square tests. P .05 was considered significant. Results: Maximum unassisted and assisted mouth opening, protrusion, left laterotrusion, and fingerthumb grip force were significantly reduced in both spinal- (n = 102) and bulbaronset (n = 40) patients compared to the control group; however, bite force was reduced only in bulbar-onset patients. ALS patients with tube feeding (n = 16) had the greatest reduction in maximum bite force and mandibular opening. There was no relationship between TMD and ALS. Oral self-injury due to biting was more frequent in the ALS group (29.9%) than in the control group (8.7%) and in the bulbar-onset group (55.0%) compared to the spinal- (20.8%) and respiratoryonset (18.2%) groups. Of the ALS patients in the study, 10% sought dental treatment related to the condition. Conclusion: The ALS patients in this study had a reduction in finger-thumb grip force that was twice as great as the reduction in bite force. The maximum range of mandibular movement was also reduced, especially in bulbar-onset patients. ALS patients did not have a higher prevalence of TMD but did have more traumatic mucosal injury than controls. The dentist should be an integral part of the multidisciplinary team to manage ALS patients. Keywords: amyotrophic lateral sclerosis, craniomandibular disorders, mandibular range of motion, occlusal force, self-biting

Aims: To investigate the prevalence and predictive factors of Sjögren's syndrome (SS) in a cohort of patients with burning mouth symptoms. Methods: A total of 125 patients with burning mouth symptoms were enrolled in a prospective study and assessed for the presence of SS. The severity of oral symptoms was evaluated by using questionnaires. Salivary flow rates and salivary scintigraphy were used to evaluate salivary function. Patient laboratory work-ups were reviewed, and SS was diagnosed by a rheumatologist based on the American- European Consensus Group criteria. The differences between the SS patient group and the non-SS patient group were analyzed with chi-square test or t test. Results: A total of 12 of the 125 enrolled patients (9.5%) had a positive autoimmune antibody test, and 6 (4.8% of the entire cohort) had SS (4 [3.2%] primary and 2 [1.6%] secondary). Patients with SS exhibited significantly decreased hemoglobin levels, an increased erythrocyte sedimentation rate, and an increased prevalence of autoantibody positive results compared to non-SS patients. Salivary scintigraphy showed that the uptake ratio of the submandibular gland in SS patients was decreased significantly. Conclusion: The prevalence of SS in patients with burning mouth symptoms was 4.8%. Therefore, clinicians who treat patients with burning mouth symptoms should evaluate laboratory findings and salivary functions to identify patients with SS. Keywords: autoantibodies, burning mouth syndrome, salivary gland, Sjögren's syndrome