Cortical and spinal evoked potential response to electrical stimulation in human rectum

Abstract

This technique can be used to assess potential abnormalities in primary afferent neural pathways innervating the rectum in several neurodegenerative and functional pain disorders.

Assessment of rectal afferent neuronal function and brain activity in patients with constipation and rectal hyposensitivity

“…In this study, to ensure the rectum (and not sigmoid colon) was being stimulated, the probe was placed at 10 cm. This is consistent with a recent study, using electrodes attached to the rectal wall, which found the optimal stimulating distance to be between 8 and 16 cm 16 from the anal verge. Stimulation of the mid to upper rectum should preclude any involvement of the somatic nerves as Chan et al.…”

“…Somatosensory evoked potentials are a widely used neurophysiological tool to investigate afferent neuronal function 14,15 ; however, the use of visceral evoked potentials in clinical research is still evolving. The technique has been assessed extensively in healthy volunteer studies, [15][16][17][18][19] and more recently used to demonstrate changes in afferent neuronal function in patients with visceral hypersensitivity and irritable bowel syndrome 20,21 and also in childhood chronic constipation. 22,23 In addition to yielding information regarding conduction velocity and response amplitude, spatial localization of brain generators (dipole sources) can be extrapolated via analysis using ''inverse modeling'' of recorded data.…”

Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal

“…Subjects were studied in the right lateral position after minimum 2‐h fast. Fifteen minutes before examination, a mini enema (Toilax ® , Orion Pharma, Espoo, Finland) was administered . The study was conducted in conformity with the Helsinki declaration, informed consent was obtained from all subjects, and the protocol was approved by the local Ethics Committee (N‐20090008).…”

“…Stimuli applied include barostat, rapid balloon distension (RBD), electrical and thermal stimulation . Gut stimulation with barostat, manual balloon inflation, or thermal probe are challenged in combination with CEPs, as slow stimuli weaken the amplitude of the signal.…”

The Physiology of Human Defecation

“…Integrity of afferent neuronal pathways can be assessed using cerebral evoked potentials [252,253] whereas efferent pathways can be evaluated using motor evoked potentials [254]; alterations have been suggested in patients with colorectal dysfunction. By measuring cerebral evoked potentials in response to rectal balloon distension, LoeningBaucke et al found that children with chronic constipation and encopresis have significantly prolonged latencies suggestive of a defect in the afferent pathway from the rectum [255].…”