Abnormal electroencephalogram in irritable bowel syndrome

Background: Irritable bowel syndrome (IBS) is a functional bowel disorder c haracterized by abdominal pain and abnormal bowel habits. IBS patients some times complain of sleep disturbance. depression, and various autonomic symp toms. Our hypothesis is that the central nervous system (CNS) might play a role in the pathogenesis of IBS, Methods: We conducted two experiments usin g an electroencephalogram (EEG) to evaluate brain activity while at rest an d during mental arithmetic stress with pharmacologic neostigmine administer ed to IBS patients. The first experiment was conducted on 48 conscious and relaxed patients (24 IBS patients and 24 normal controls). EEG recordings w ere evaluated for visual and power spectrum data. In the second experiment colonic manometric studies combined with EEG recordings were performed in 2 1 of 24 IBS patients and 8 of 24 normal controls under mental arithmetic st ress and the administration of neostigmine. Results: Inspection of the EEG showed significantly greater EEG abnormality in the IBS patients (29.2%) th an in the controls ( 4.2%) (P < 0.02). In the power spectrum analysis of th e EEG the IBS patients showed significantly greater beta power percentage t han did the normal subjects (P < 0.02). A significant positive correlation was observed between the colonic motility index and beta power percentage a fter the administration of neostigmine, 10 mu g/kg. only in the IBS patient s (P < 0.05. Conclusion: A brain dysfunction as indexed by the EEG suggests an electrophysiologic brain-gut interaction in IBS.