Detection thresholds for Semmes-Weinstein monofilaments (SW tester), a 5-Hz rectangular electric stimulus and a warming stimulus were measured in the normal lower lip and chin area of 242 subjects (87 males, 155 females). Differences in terms of the stimulated region, gender and age were examined and the coefficients of variance (CVs) of the thresholds of subjects for the various stimuli were examined to determine the reliability of the measurements.
The lower lip was more sensitive than the chin area to all stimuli. The threshold for the automatically increased warming stimulus including reaction time was higher than that for a specific warming stimulus excluding the reaction time. The thresholds of the lower lip and chin area for all stimuli tended to be higher for elderly subjects than younger ones, except for the thermal threshold of the lower lip; the thermal threshold of the lower lip was found to be independent of age. The thresholds for the warming stimulus of the lower lip and chin area were independent of gender, whereas the thresholds for the SW tester of the lower lip and chin area appeared to be related to gender in subjects aged in their 30s to 60s. Moreover, the thresholds for the 5-Hz rectangular electric stimulus appeared to be related to gender in subjects in their teens to 40s. The CVs of the thresholds to the 5-Hz rectangular electric stimulus and warming stimulus were lower than those to the SW tester.
