Rectal visceral sensitivity and autonomic function in female patients with irritable bowel syndrome (IBS)
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AbstractIrritable bowel syndrome (IBS) is a common functional disorder characterised by chronic recurring abdominal pain. Female patients with IBS were recruited from newspaper advertisements and from general practitioners and compared to healthy women. Fifty-two IBS patients and 25 healthy controls constituted a pool of participants, and they were the basis for the clinical studies performed in this thesis in gastroenterology.
The exact pathophysiology of IBS is still unknown. Probably it is caused from an interaction of both biological and psychosocial factors, and it is assumed that different pathogenetic factors may be involved in different subgroups of IBS. This study was conducted to see if altered function in the brain-gut axis characterized a population of IBS patients mainly without psychiatric comorbid disorders. The main focus was on rectal visceral sensitivity examined with a barostat, but autonomic and cerebral functions were also explored. Parasympathetic controlled respiratory sinus arrhythmia (RSA) and sympathetic controlled skin conductance were used as indexes of autonomic functions. Cerebral function was measured with event-related potentials (ERP).
Our results demonstrated that the reproducibility of visceral sensitivity testing in the rectum using the barostat method may be applicable when comparing groups of subjects. The IBS patients had normal visceral sensitivity with regard to pressure thresholds, but the volume at the discomfort threshold was lowered compared to healthy controls. Our study suggested that the lowered volume threshold was due to increased rectal tone. Further, our findings support the increasing evidence of autonomic dysfunction in IBS patients. A subgroup of the IBS patients with phobic anxiety had decreased rectal gas sensitivity in addition to altered brain processing compared to IBS patients without psychiatric comorbidity, suggesting that comorbid phobic anxiety interferes with the cerebral processing of visceral information.
List op papers
Paper I. Spetalen S, Jacobsen MB, Vatn MH, Blomhoff S, Sandvik L.: Visceral sensitivity in irritable bowel syndrome and healthy volunteers: reproducibility of the rectal barostat. 2004.Dig Dis Sci. 49(7-8):1259-64.
Paper II. Spetalen S, Sandvik L, Blomhoff S, Jacobsen MB.: Rectal Visceral Sensitivity in Women with Irritable Bowel Syndrome without Psychiatric Comorbidity Compared with Healthy Volunteers. Submitted
Paper III. Spetalen S, Sandvik L, Blomhoff S, Jacobsen MB.: Autonomic function at rest and in response to emotional and rectal stimuli in women with irritable bowel syndrome. Dig Dis Sci. 53(6):1652-9. 2008
Paper IV. Blomhoff S, Spetalen S, Jacobsen MB, Malt UF. Phobic anxiety changes the function of brain-gut axis in irritable bowel syndrome. Psychosom 63(6):959-65.: 2001 Psychosom 63(6):959-65.: 2001