title: Distinct neurophysiological profiles in irritable bowel syndrome.
abstract: The objective of this study was to determine whether cortical evoked potentials (CEPs) can define neurophysiological patterns in irritable bowel syndrome (IBS). In this prospective study of consecutive patients attending secondary and tertiary centers, patients with Rome II-defined IBS underwent rectal sensory and pain threshold (RST and RPT, respectively) testing with electrical stimulation on three separate visits. CEPs were collated for 75% pain thresholds, and anxiety [Spielberger State-Trait Anxiety Inventory (SSTAI)] questionnaires were completed. Subjects were 33 IBS patients (27 female, mean age 40.1 yr) and 21 healthy controls (14 female, mean age 31.4 yr). At visit 3, RPT was significantly lower [mean (95% CI)] in IBS patients than in control subjects: 58.2 mA (48.0-68.5) vs. 79.5 mA (69.3-89.6) (P < 0.01). No significant differences were observed in CEP latencies and amplitudes between visits 1, 2, and 3 within each group, except P2 latency for controls (P = 0.04) and N2 latency (P = 0.04) and N2 amplitude (P = 0.02) for IBS patients. Group comparisons showed significant differences in 3-day mean RPT, CEP amplitudes, and CEP latencies between IBS patients and controls. RPT <50 mA and P1 latency >106 ms were identified four IBS subgroups: 24% were hypersensitive, 12% were hypervigilant, 15% were hyposensitive, and 49% exhibited normal P1 latency and pain threshold. CEPs are reliable and reproducible measures of early sensory processing. Identification of four IBS neurophysiological patterns highlights its heterogeneous nature. These findings mark the first step toward personalized medicine in IBS, whereby therapy may be directed at the underlying physiological process.
authors.affiliation: Gastrointestinal Physiology Department, St. Mark’s Hospital Campus, Imperial College, Harrow, Middlesex, UK. naila.arebi@imperial.ac.uk
authors.forename: Naila
authors.initials: N
authors.lastname: Arebi
authors.forename: Dominic C
authors.initials: DC
authors.lastname: Bullas
authors.forename: George E
authors.initials: GE
authors.lastname: Dukes
authors.forename: Salma
authors.initials: S
authors.lastname: Gurmany
authors.forename: Kirsty J
authors.initials: KJ
authors.lastname: Hicks
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kamm
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Hobson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001007:Anxiety / Q000209:etiology; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000503:physiopathology*; D004558:Electric Stimulation; D004569:Electroencephalography; D004739:England; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D008297:Male; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D010641:Phenotype; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011930:Reaction Time; D012007:Rectum / Q000294:innervation*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires