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.

Visceral hypersensitivity in irritable bowel syndrome: evidence for involvement of serotonin metabolism – a preliminary study

“…The blunted, or practically absent, perceptive response to serotonergic stimulation in the non‐hypersensitive patients could be the result of a yet unidentified, deficit in the transmission of the perceptive stimulus from the afferent nerve endings to the central nervous system, which could not be investigated in further detail in the current study. Correct identification of these responses could be possible using electrophysiological studies, such as cerebral evoked potentials . In addition, it remains to be elucidated what the underlying serotonin‐related mechanism are for the development of such differential perceptional status in IBS patients.…”

Does central sensitization help explain idiopathic overactive bladder?

“…Temporal summation is presumed to be the psychophysical manifestation of central sensitization 41,43 and is the most widely accepted index for measurement of central sensitization in the context of pain available in the published literature 43 . QST is frequently used for clinical assessment and phenotyping of patients with chronic conditions such as functional abdominal pain 44–46 , IBS 47 , TMJD 48 , fibromyalgia 49,50 , IC/BPS 51 , and lower-back pain 44 .…”

“…However, results of these studies have been inconsistent and difficult to interpret 103–107 . Peripheral QST with either mechanical or heat stimuli in patients with OAB has not been reported; therefore, it remains unknown if patients with OAB have the more generalized hyperaesthesia, allodynia or hyperalgesia to evoked pain stimuli on psychophysical testing reported in some other patients with central sensitization-related disorders 44,47,49,50 . Currently, to our knowledge, no published reports are available regarding temporal summation of evoked painful stimuli in patients with OAB, which might provide quantitative information on the existence or extent of central sensitization in this population.…”

Brain and Gut Interactions in Irritable Bowel Syndrome: New Paradigms and New Understandings

“…Functional studies have excellent spatial resolution for superficial layers, whereas it is somewhat limited for deeper structures such as the thalamus and brain stem. Also, this technique has poor temporal resolution, and is not specific enough to assess neuronal activity distally related to stimulus (64). Hence, further studies are needed to comprehensive understand the changes in cortical and subcortical function.…”