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Objective : The mechanisms involved in the relationship between pain perception and hypertension are poorly understood. This study has sought to investigate whether the spontaneous baroreflex sensitivity and the autonomic nervous system balance are related to hypertension-associated hypoalgesia. Methods : In the morning, 73 untreated male subjects (45 hypertensives, 28 normotensives) were submitted to a simultaneous recording of electrocardiographic and blood pressure signals in resting condition. The tracings were analysed off-line to evaluate the spectral components of the low frequency (LF) and high frequency (HF) powers (autoregressive algorithm; LF/HF ratio used in subsequent analysis as an index of sympathovagal balance), and the alpha LF ( α LF ), an index of baroreflex sensitivity. After the rest period, the subjects underwent dental pain perception evaluation (pulpar tester: test current increasing from 0 to 0.03 mA, expressed in relative Units) to determine the dental pain threshold and tolerance. Afterwards, a 24-h ambulatory blood pressure monitoring was performed. Results : A significant relationship was observed between α LF and pain threshold ( r =−0.34; p =0.003). When a multivariate analysis was computed to control for age, 24-h systolic pressure and LF/HF ratio, α LF was a predictive independent factor associated with pain threshold (model p =0.019; r =−0.31; p =0.025). Moreover, the 24-h systolic pressure was independently associated with pain threshold (model p =0.019; r =0.30, p =0.031). The relationship between α LF and relative tolerance was not statistically significant. When the association between the LF/HF ratio and pain sensitivity was assessed as a secondary endpoint, no significant relationship was observed. Since no significant interaction was found, the effect of α LF and LF/HF ratio on pain perception was assumed to be similar in normotensive and hypertensive subjects. Conclusions : The relationship found between unstimulated baroreflex sensitivity and pain threshold suggests a modulation of pain perception by baroreflex pathways in hypertension-associated hypoalgesia. In a baseline condition, the autonomic nervous system balance does not seem to influence pain sensitivity.

Objective To investigate dental pain perception in a large group of essential hypertensive subjects. Methods A total of 130 hypertensive patients together with 51 normotensive subjects were submitted to tooth-electrical stimulation to determine the dental pain threshold (occurrence of pulp sensation) and tolerance (time when the subject asked for the test to be stopped). Blood pressure was measured at rest, before pain perception evaluation, and during a 24 h period by ambulatory monitoring. Results The normotensive and hypertensive subjects differed with regard to pain threshold (P= 0.002) and tolerance (P=0.01). Pain perception variables were significantly correlated with both resting blood pressure and 24 h, diurnal and nocturnal arterial pressures, the correlation between pain threshold and 24 h systolic blood pressure being the most significant (r = 0.31, P

Introduction: The aim of this study was to determine whether the degree of blood pressure elevation and/or a genetic predisposition to hypertension have a major role in determining a reduced pain perception in hypertensives. The reasons underlying the relationship between blood pressure elevation and pain perception mechanisms are not completely understood. Methods: One hundred and four untreated hypertensive patients (65 subjects with and 39 without a positive parental history of hypertension) together with a control group of 42 subjects (20 normotensive offspring of normotensive parents, and 22 normotensive offspring of hypertensive parents) were submitted to standard blood pressure evaluation, 24-h blood pressure monitoring and dental pain perception evaluation. Results: Both pain threshold and tolerance were found to be higher in hypertensive than normotensive subjects (P