Assessment of Gastrointestinal Sensation – A Review

Abstract

Understanding the mechanisms of symptoms in patients with gastrointestinal disorders remains a great challenge. One of the major problems facing clinicians in this area is the limited information gained from subjective outcome measures commonly used to assess these conditions. To address this, various stimulation and recording techniques, commonly used by neurologists, have been adapted to study gastrointestinal sensory processing. This review article provides an overview of this expanding research area and discusses the advantages and disadvantages of each approach.

New technologies to investigate the brain-gut axis

“…Visceral pain has been contrasted with pain arising from superficial skin structures [34,35] . Recent reviews have summarized imaging findings in normal GI sensation [36][37][38] . Recently, a number of new technologies have emerged within imaging of the brain-gut axis, and in this review we focus on the EEG techniques where signal analyses have made it possible to follow the early and pain specific pathways to the brain with high temporal and spatial resolution.…”

“…As has been outlined, the PAG is an important structure involved in the modulation of spinal pain processing, and the above finding suggests that a proportion of IBS patients have inadequate activation of brain regions involved with antinociception. Mayer et al [38] have recently reviewed imaging studies in FGID which has been critiqued by Hobson and Aziz [36,37,72] . "Visceral hypersensitivity" is a hallmark feature in IBS patients, who show an abnormal pattern of ACC activation during pain perception which is an interesting parallel to ACC activation relative to increasing pain perception in healthy subjects [43,73,74] ; hemispheric preference, as well as cognitive style of information processing served as indicators of covert changes in brain functions in 21 adult IBS patients [75] ; and abnormal cerebral processing of oesophageal stimuli was found in patients with noncardiac chest pain [50,51] .…”

Multimodal sensory testing of the rectum and rectosigmoid: development and reproducibility of a new method

“…2 The main disadvantage is the non-physiological stimulus and the lack of specificity of nerve fibre stimulation, bypassing receptors and depolarizing free nerve-endings directly. 17,26 However, the direct effect may also be advantageous as central pain pathways can be studied directly. 26 As electrostimulation is not restricted to the gut wall, somatic nerves and tissue in close vicinity may also be activated.…”

“…17,26 However, the direct effect may also be advantageous as central pain pathways can be studied directly. 26 As electrostimulation is not restricted to the gut wall, somatic nerves and tissue in close vicinity may also be activated. 27,28 The ICC value at PDT of 0.9 shows highly reproducibility, in accordance with other studies, where reproducibility of electrical responses was tested in oesophagus 6 and rectum.…”

“…Thermo-sensitive receptors in the GI tract have been demonstrated in animals 29,30 and in all segments of the human GI tract. 6,11,22,26,27 However, the distribution of receptors throughout the GI tract is variable. Thermal stimulation in the rectum should -unlike the oesoph-agus that may be in regular contact with hot or cold foodstuff -be regarded as non-physiological.…”