Background: Changes in quantitative sensory testing (QST) parameters following topical anaesthesia could contribute to better elucidate underlying mechanisms of somatosensory alterations in temporomandibular disorder (TMD) pain patients. This placebo-controlled crossover investigation compared the somatosensory profile following topical anaesthesia between TMD patients (n = 20) and healthy participants (n = 20).
Methods: Cold detection threshold, warm detection threshold, cold pain threshold, heat pain threshold, mechanical detection threshold, mechanical pain threshold, wind-up ratio and pressure pain threshold were assessed on the skin overlying the masseter at three consecutive days (baseline and immediately after lidocaine 4%/placebo cream). Mixed ANOVA and a coding system that accounts for the diversity of types of peripheral axons associated with the somatosensory parameters were applied for data analysis.
Results: The lidocaine application caused no changes in the somatosensory sensitivity in the masseter region in TMD patients (P > .050), but sensitivity to cold, cold pain, touch and pinprick stimuli were reduced after topical anaesthesia in healthy participants (P < .050). Also, the degree of topical anaesthesia was greater in healthy participants (P = .008). The coding system suggested that TMD patients presented only Aδ-fibre block, whereas a combination of either Aβ- and/or C-fibre block was observed in 35% of healthy participants in addition to Aδ-fibre block following lidocaine application.
Conclusion: Quantitative sensory testing can be successfully applied to identify meaningful differences in the degree of hypoalgesia and hypoesthesia following short-time topical anaesthesia.
Keywords: central sensitisation; local anaesthesia; musculoskeletal pain; pain thresholds; sensory thresholds; temporomandibular disorders.
© 2019 John Wiley & Sons Ltd.