The autonomic nervous system (ANS) integrates afferent and motor activity for homeostatic processes including pain. The aim of the study was to compare hitherto poorly characterised relations between brainstem autonomic control and personality in response to visceral and somatic pain. Eighteen healthy subjects (16 females, mean age 34) had recordings during rest and pain of heart rate (HR), cardiac vagal tone (CVT), cardiac sensitivity to baroreflex (CSB), skin conductance level (SC), cardiac sympathetic index (CSI) and mean blood pressure (MBP). Visceral pain was induced by balloon distension in proximal (PB) and distal (DB) oesophagus and somatic pain by nail-bed pressure (NBP). Eight painful stimuli were delivered at each site and unpleasantness and intensity measured. Personality was profiled with the Big Five inventory. (1) Oesophageal intubation evoked "fight-flight" responses: HR and sympathetic (CSI, SC, MBP) elevation with parasympathetic (CVT) withdrawal (p<0.05). (2) Pain at all sites evoked novel parasympathetic/sympathetic co-activation with elevated HR but vasodepression (all p<0.05). (3) Personality traits correlated with slope of distal oesophageal pain-related CVT changes wherein more neurotic-introvert subjects had greater positive pain-related CVT slope change (neuroticism r 0.8, p<0.05; extroversion r -0.5, p<0.05). Pain-evoked heart rate increases were mediated by parasympathetic and sympathetic co-activation - a novel finding in humans but recently described in mammals too. Visceral pain-related parasympathetic change correlated with personality. ANS defence responses are nuanced and may relate to personality type for visceral pain. Clinical relevance of these findings warrants further exploration.
Bibliographical notePaine, Peter Kishor, Jessin Worthen, Sian F Gregory, Lloyd J Aziz, Qasim Cancer Research UK/United Kingdom Medical Research Council/United Kingdom Comparative Study Research Support, Non-U.S. Gov't Netherlands Pain Pain. 2009 Aug;144(3):236-44. Epub 2009 Apr 23.
- Autonomic Nervous System/anatomy & histology/*physiology
- Blood Pressure/physiology
- Brain Stem/anatomy & histology/physiology
- Genetic Predisposition to Disease/psychology
- Heart Rate/physiology
- Neurotic Disorders/physiopathology/psychology
- Pain Measurement/methods/psychology
- Pain Threshold/physiology/psychology
- Parasympathetic Nervous System/anatomy & histology/physiology
- Physical Stimulation
- Psychophysiologic Disorders/*physiopathology/*psychology
- Sympathetic Nervous System/anatomy & histology/physiology
- Visceral Afferents/anatomy & histology/physiology