Predominant symptoms in irritable bowel syndrome correlate with specific autonomic nervous system abnormalities.

BACKGROUND/AIMS: Irritable bowel syndrome may be influenced by the autonomic nervous system. Abnormalities in autonomic function, colon transit time, and psychological profiles in 21 patients were assessed.
METHODS: Using modified Manning criteria for irritable bowel syndrome, patients were classified as constipation-predominant or diarrhea-predominant. Autonomic function was determined by one vagal cholinergic and two sympathetic adrenergic measures. Colon transit was assessed by radiopaque markers, and psychological profiles were determined by three inventories.
RESULTS: Autonomic function tests showed that diarrhea-predominant subgroup values for one sympathetic adrenergic measure (postural adjustment ratio) were significantly different from controls (P < 0.01). Constipation-predominant subgroup values were significantly lower for the vagal cholinergic measure R-R interval (P < 0.05). Colon transit measures differed by subgroup in left, right, rectosigmoid, and total colon transit times. Both subgroups differed significantly from controls on psychological measures; the constipation subgroup showed more psychological distress.
CONCLUSIONS: Irritable bowel syndrome specific-symptom subgroups had different patterns of autonomic functioning, colonic transit, and psychological measures. The constipation subgroup is associated with a cholinergic abnormality and the diarrhea-predominant subgroup with an adrenergic abnormality. These findings suggest specific associations between the autonomic nervous system, predominant physical symptoms, colon transit time, and psychological factors in patients with irritable bowel syndrome.