ABSTRACT
BACKGROUND: The mechanisms of interindividual variations in visceral pain sensitivity remain poorly understood. We characterized the neuroendocrine responses to rectal distensions in healthy individuals with high vs. low rectal pain sensitivity. METHODS: Rectal sensory and pain thresholds were determined, and a series of random painful distensions was carried out. Eighteen subjects were stratified into groups with a low rectal pain threshold ("High Sensitivity" group) vs. a high rectal pain threshold ("Low Sensitivity" group) by median split, and were compared with regard to adrenocorticotropic hormone (ACTH) and cortisol, cardiovascular, and emotional responses. RESULTS: Distensions led to an anticipatory stress response, reflected by elevated baseline anxiety, and increased baseline ACTH and cortisol in both groups. In response to distensions, the "Low Sensitivity" group showed significantly greater ACTH and cortisol concentrations analysis of variance (ANOVA time x group for ACTH: p<.05; for cortisol: p<.01), and elevated diastolic blood pressures (BP) (ANOVA group: p<.01) when compared to the "High Sensitivity" group. CONCLUSIONS: Painful rectal distensions are associated with a pronounced anticipatory stress response, reflected by elevated anxiety and elevated stress hormones. Individuals with high rectal pain sensitivity differ from those with low pain sensitivity in distension-induced hormonal and blood pressure responses, suggesting that neuroendocrine responses may be relevant to the pathophysiology of visceral hyperalgesia.
Subject(s)
Abdominal Pain/physiopathology , Adrenocorticotropic Hormone/blood , Blood Pressure/physiology , Hydrocortisone/blood , Pain Threshold/physiology , Rectum/physiology , Abdominal Pain/complications , Abdominal Pain/psychology , Adaptation, Psychological/physiology , Adult , Analysis of Variance , Anxiety/etiology , Anxiety/physiopathology , Dilatation , Female , Humans , Hypothalamo-Hypophyseal System/physiology , Individuality , Male , Pain Threshold/psychology , Pituitary-Adrenal System/physiology , Rectum/physiopathology , Reference Values , Stress, PsychologicalABSTRACT
OBJECT: The effect of increased intracranial pressure (ICP) on cerebral venous blood flow has been the subject of very few clinical and experimental studies. The authors assessed the usefulness of venous transcranial Doppler (TCD) ultrasonography as a noninvasive monitoring tool for predicting raised ICP. METHODS: Serial venous TCD studies of the basal vein of Rosenthal and the straight sinus (SS) were prospectively performed in 30 control volunteers and 25 patients with raised ICP. Correlations with ICP data were calculated using a multivariate regression model. Venous blood flow velocities (BFVs) in the basal vein of Rosenthal showed, within a certain range, a linear relationship between mean ICP and maximal venous BFV (r = 0.645; p<0.002). Moreover, a linear relationship was found for maximal venous BFVs in the SS and mean ICP (r = 0.928; p<0.0003). CONCLUSIONS: Venous TCD studies may provide an additional noninvasive monitoring tool for raised ICP and give further insights into the cerebral venous hemodynamics present during raised ICP.
