Evidence for alterations to dynamic quantitative sensory tests in patients with chronic temporomandibular myalgia: A systematic review of observational studies with meta‐analysis

Abstract

Background Conflicting results exist between somatosensory profiles of patients with temporomandibular myalgia (TMDm). The objective of this review was to examine whether adults with TMDm show altered responses to dynamic quantitative sensory tests compared with healthy controls. Methods We searched five electronic databases for studies, excluding those without suitable controls or where TMDm was associated with confounding non‐musculoskeletal disorders. Risk of bias was assessed with the SIGN case‐control study checklist. Findings were structured around dynamic quantitative sensory tests and their localization. Where possible, we performed meta‐analysis with a random inverse variance model to compare patients with TMDm and healthy controls. Statistical heterogeneity was estimated with Chi² test and inconsistency index, I². Results We extracted data from 23 studies comprising 1284 adults with chronic TMDm and 2791 healthy controls. Risk of bias was assessed as high for 20 studies. Mechanical temporal summation, the most studied phenomenon (14 studies), is increased in the upper limb of patients with TMDm (SMD = 0.43; 95% CI: .11 to .75; p = .009) but not in the jaw area (p = .09) or in the cervical area (p = .29). Very little evidence for altered thermal temporal summation (five studies), conditioned pain modulation (seven studies), exercise‐induced hypoalgesia (two studies), placebo analgesia (two studies), stress‐induced hypoalgesia (one study) and offset analgesia (one study) was found. Discussion A major limitation of this review was the risk of bias of included studies. Future studies would benefit from following methodological guidelines and consideration of confounding factors.

Sensory innervation of masseter, temporal and lateral pterygoid muscles in common marmosets

“…Thus, TMD-M is rarely accompanied by clinical signs and histopathologic evidence of injury or inflammation (Ettlin et al, 2021). Therefore, some studies (Kosek et al, 2016) have classified TMD-M as nociplastic pain (Cayrol et al, 2022). Despite these debatable points, there is an agreement that TMD-M leads to sensitization of nociceptive and non-nociceptive trigeminal ganglia (TG) sensory neurons innervating the masticatory muscles, leading to increase signal input into the central nervous system (Fitzcharles et al, 2021).…”

Chronic temporomandibular disorders are associated with higher propensity to develop central sensitization: a case–control study

“…2,5,21,25,32,41 Through quantitative sensory testing, studies have shown that individuals with TMD tend to have lower pressure pain thresholds and experience more pain in response to repeated nociceptive stimuli (ie, temporal summation) at extratrigeminally innervated sites. 12,21 Besides, a recent prospective study showed that pressure pain thresholds throughout the body decrease after the onset of TMD and return to normal after TMD remission. 42 These findings suggest alterations in trigeminal and extratrigeminal nociceptive processing, but are hardly indicative of the pathophysiology of TMD.…”

“…42 These findings suggest alterations in trigeminal and extratrigeminal nociceptive processing, but are hardly indicative of the pathophysiology of TMD. 4,10 Moreover, the sensitivity to stimuli is not found to be globally altered in patients with TMD 12,16,21 ; therefore, studies on specific physiological mechanisms are needed.…”

Sensory innervation of masseter, temporal and lateral pterygoid muscles in common marmosets

“…Thus, TMDM is often not accompanied by such clinical signs as histopathologic evidence of injury or inflammation 7 . Therefore, some studies 8 have classified TMDM as nociplastic pain 9 . Despite these debatable points, there is an agreement that TMDM leads to sensitization of nociceptive and maybe non-nociceptive trigeminal ganglia (TG) sensory neurons innervating the masticatory muscles, leading to increase signal input into the central nervous system 10 .…”