Quantitative sensory testing in patients with the muscle pain subtype of temporomandibular disorder: a systemic review and meta-analysis

Abstract

Objectives: This meta-analysis aimed to evaluate quantitative sensory testing (QST) evidence for pain processing in patients with the muscle pain subtype of temporomandibular disorders (mTMD).

Materials and methods: A comprehensive systematic electronic search strategy was performed in online literature databases. All full-text observational studies published up to July 2021 with the aim of investigating pain sensitization in humans with mTMD using QST measures were eligible for inclusion. Meta-analysis of QST data was performed using a random effects model, which included results comparing patients with mTMD to healthy controls, and standard mean difference (SMD) results were analyzed.

Results: Twelve studies with 732 participants (371 patients with mTMD and 361 healthy controls) were analyzed following screening and quality appraisal. Compared with healthy controls, patients with mTMD had significantly lower pressure pain threshold (SMD - 1.10, 95% confidence interval [CI] - 1.52 to - 0.68) with high heterogeneity (Tau² = 0.61, I² = 86%), and significantly lower mechanical pain threshold (SMD - 0.64, 95% CI - 0.95 to - 0.32) with no heterogeneity (Tau² = 0.00, I² = 0%). No difference was observed in the cold pain threshold (SMD 0.16, 95% CI - 0.13 to 0.45), heat pain threshold (SMD - 0.13, 95% CI - 0.40 to 0.15), and wind-up ratio (SMD 0.63, 95% CI - 0.11 to 1.38) between patients with mTMD and healthy controls. Other QST parameters were also discussed.

Conclusions: The study results suggest that the pain processing of deep tissues is likely sensitized in mTMD and calls for more QST studies with standard procedures to reduce inter-study heterogeneity.

Clinical relevance: The major findings of this meta-analysis support using PPT to examine the pain processing in patients with mTMD in clinical scenario.

Keywords: Central sensitization; Pain processing; Peripheral sensitization; Quantitative sensory testing; Temporomandibular disorders.