EFFECTS OF ARITHMETIC MENTAL STRESS TEST ON HYPERTENSION-RELATED HYPALGESIA

Aim: Though hypertension-related hypalgesia has been described, little is known about possible variation of pain perception after mental str ess. The aims of the present study were to determine (1) whether menta l stress can influence pain perception in normotensive and hypertensiv e subjects and (2) whether blood pressure levels before pain evaluatio n can account for changes in pain sensitivity. Patients and methods: A pulpar test (graded increase in test current of 0-0.03 mA applied on healthy teeth) was performed twice (time interval 15 min) in 62 subjec ts. Thirty-eight subjects (group 1) performed an arithmetic mental str ess test immediately after the first pulpar test while 24 subjects (gr oup 2) did not. The pain threshold (occurrence of pulp sensation) was evaluated as the mean value of three teeth tested on each subject and as the value on the most sensitive tooth. Results: Twenty-eight subjec ts with normal 24-h blood pressure showed a lower mean pain threshold than 34 subjects with high 24-h blood pressure values (P<0.02). In gro up 1 (20 normotensives, 18 hypertensives), even when the mental stress increased the pretest blood pressure, the pressure values immediately before both pulpar tests remained similar. In the second pulpar test, a significant increase in the pain threshold on the most sensitive to oth was observed in group 1 (P<0.005). Though a trend towards an incre ase in the pain threshold was found in both the subgroups of normotens ive and hypertensive subjects, the difference was significant in hyper tensives only. However, group 2 subjects showed unchanged pain sensiti vity on the second test. Conclusions: A mental stress-induced reductio n in pain sensitivity was observed in the absence of change in arteria l pressure measured immediately before pulpar tests. A blood pressure increase during the test and, more likely, cortical and humoral activa tion during stress, may account for the variation found in pain percep tion.