Age differences in pain sensitivity and effect of topical lidocaine on the tongue in healthy female subjects

PURPOSE: To assess the sensitivity and the effect of topical lidocaine on the tongue by quantitative sensory testing, comparing healthy middle-aged female subjects with healthy young female subjects. METHODS: Sixteen healthy female subjects including eight in their fifties and eight in their twenties participated. They participated in two sessions at a 2-week interval in randomized order: lidocaine (experimental session) or placebo gel (placebo session) was applied on the tongue tip for 5min. The following parameters were taken on the tongue tip before and after application of the gel in each session: tactile detection threshold (TDT), filament-prick pain detection threshold (FPT), and numerical rating scale (NRS). RESULTS: An increase of both TDT and FPT and a decrease of NRS were found after lidocaine application in both middle-aged and young female subjects. In the elder females, an increase of TDT, FPT, and NRS was also found after placebo gel application. However, the changes were not statistically significant, except for FPT in middle-aged subjects. CONCLUSION: The reactions found after lidocaine application in middle-aged female subjects could be due to habituation as well as to the post-application effect of placebo gel. Placebo-induced changes appeared more pronounced in the elder females.