Reproducibility of quantitative sensory testing applied to musculoskeletal orofacial region: Site and sex differences.

BACKGROUND: This study estimated the inter-rater reliability and agreement of the somatosensory assessment performed at masseter and temporomandibular joint (TMJ) region in a group of healthy female and male participants. METHODS: Forty healthy participants (20 men and 20 women) were evaluated in two sessions by two different examiners. Cold detection threshold (CDT), warm detection threshold (WDT), thermal sensory limen (TSL), cold pain threshold (CPT), heat pain threshold (HPT), mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind-up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying TMJ and masseter body. Mixed ANOVA, intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were applied to the data (α = 5%). Nonoverlapping 95% confidence intervals (95% CI) of ICCs were considered significantly different. RESULTS: The ICCs of 77% of all quantitative sensory testing (QST) measurements were considered fair to excellent (ICCs: 0.47-0.97), and WUR presented the lowest values. The reliability of WDT, TSL and HPT of masseter was significantly higher than TMJ, whereas the MDT reliability of TMJ was higher than masseter. In addition, the following combination of test/sites presented significantly lower ICCs for women: HPT, MDT of TMJ and MPT of both TMJ and masseter. Finally, the highest SEM values were presented for CPT and MPT. CONCLUSION: The overall somatosensory assessment of the masticatory structures performed by two examiners can be considered sufficiently reliable to discriminate participants, except WUR. Possible site and sex influences on the reproducibility parameters should be taken into account for an appropriate interpretation and clinical application of QST. SIGNIFICANCE: The test site and participant's sex can significantly influence the relative reliability and agreement of quantitative sensory testing applied to musculoskeletal orofacial region, which affect the capacity to discriminate participants and to evaluate changes over time.

Muscle hardness and masticatory myofascial pain: Assessment and clinical relevance.

The impression of increased muscle hardness in painful muscles is commonly reported in the clinical practice but may be difficult to assess. Therefore, the aim of this review was to present and discuss relevant aspects regarding the assessment of muscle hardness and its association with myofascial temporomandibular disorder (TMD) pain. A non-systematic search for studies of muscle hardness assessment in patients with pain-related TMDs was carried out in PubMed, Cochrane Library, Embase and Google Scholar. Mechanical devices and ultrasound imaging (strain and shear wave elastography) have been consistently used to measure masticatory muscle hardness, although an undisputable reference standard is yet to be determined. Strain elastography has identified greater masseter hardness of the symptomatic side in patients with unilateral myofascial TMD pain when compared to the contralateral side and healthy controls (HC). Likewise, shear wave elastography has shown greater masseter elasticity modulus in patients with myofascial TMD pain when compared to HC, which may be an indication of muscle hardness. Although assessment bias could partly explain these preliminary findings, future randomised controlled trials are encouraged to investigate this relationship. This qualitative review indicates that the muscle hardness of masticatory muscles is still a rather unexplored field of investigation with a good potential to improve the assessment and potentially also the management of myofascial TMD pain. Nonetheless, the current evidence in favour of increased hardness in masticatory muscles in patients with myofascial TMD pain is weak, and the pathophysiological importance and clinical usefulness of such information remain unclear.