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The gastrointestinal (GI) tract is a system of organs within multicellular animals which facilitates the ingestion, digestion, and absorption of food with subsequent defecation of waste. A complex arrangement of nerves and ancillary cells contributes to the sensorimotor apparatus required to subserve such essential functions that are with the exception of the extreme upper and lower ends of the GI tract normally subconscious. However, it also has the potential to provide conscious awareness of injury. Although this function can be protective, when dysregulated, particularly on a chronic basis, the same system can lead to considerable morbidity. The anatomical and molecular basis of gastrointestinal nociception, conditions associated with chronic unexplained visceral pain, and developments in treatment are presented in this review. [ABSTRACT FROM AUTHOR]

Patients with functional gastrointestinal disorders often demonstrate abnormal visceral sensation. Currently, rectal sensation is assessed by manual balloon distension or barostat. However, neither test is adaptable for use in the neurophysiological characterization of visceral afferent pathways by sensory evoked potentials. The aim of this study was to assess the reproducibility and quality of sensation evoked by electrical stimulation (ES) and rapid balloon distension (RBD) in the anorectum and to apply the optimum stimulus to examine the visceral afferent pathway with rectal evoked potentials. Healthy subjects (n = 8, median age 33 yr) were studied on three separate occasions. Variability, tolerance, and stimulus characteristics were assessed with each technique. Overall ES consistently invoked pain and was chosen for measuring rectal evoked potential whereas RBD in all cases induced the strong urge to defecate. Rectal intraclass correlation coefficient (ICC) for ES and RBD (0.82 and 0.72, respectively) demonstrated good reproducibility at pain/maximum tolerated volume but not at sensory threshold. Only sphincter ICC for ES at pain showed acceptable between-study reproducibility (ICC 0.79). Within studies ICC was good (>0.6) for anorectal ES and RBD at both levels of sensation. All subjects reported significantly more unpleasantness during RBD than ES (P < 0.01). This study demonstrates that ES and RBD are similarly reproducible. However, the sensations experienced with each technique differed markedly, probably reflecting differences in peripheral and/or central processing of the sensory input. This is of relevance in interpreting findings of neuroimaging studies of anorectal sensation and may provide insight into the physiological characteristics of visceral afferent pathways in health and disease. [ABSTRACT FROM AUTHOR]

Background: Oesophageal acid infusion induces enhanced pain hypersensitivity in non-acid exposed upper oesophagus (secondary hyperalgesia) in patients with non-cardiac chest pain, thus suggesting central sensitisation contributes to visceral pain hypersensitivity in functional gut disorders (FGD). Perceptual wind-up (increased pain perception to constant intensity sensory stimuli at frequencies ⩾0.3 Hz) is used as a proxy for central sensitisation to investigate pain syndromes where pain hypersensitivity is important (for example, fibromyalgia). Aims: Wind-up in central sensitisation induced human visceral pain hypersensitivity has not been explored. We hypothesised that if wind-up is a proxy for central sensitisation induced human visceral pain hypersensitivity, then oesophageal wind-up should be enhanced by secondary hyperalgesia. Methods: In eight healthy volunteers (seven males; mean age 32 years), perception at pain threshold to a train of 20 electrical stimuli applied to the hand and upper oesophagus (UO) at either 0.1 Hz (control) or 2 Hz was determined before and one hour after a 30 minute lower oesophageal acid infusion. Results: Wind-up occurred only with the 2 Hz train in the UO and hand (both p=0.01 ). Following acid infusion, pain threshold decreased (17 (4)%; p=0.01) in the UO, suggesting the presence of secondary hyperalgesia. Wind-up to the 2 Hz train increased in the UO (wind-up ratio 1.4 (0.1) to 1.6 (0.1); p=0.03) but not in the hand (wind-up ratio 1.3 (0.1) and 1.3 (0.1); p=0.3) Conclusion: Enhanced wind-up after secondary oesophageal hyperalgesia suggests that visceral pain hypersensitivity induced by central sensitisation results from increased central neuronal excitability. Wind-up may offer new opportunities to investigate the contribution of central neuronal changes to symptoms in FGD. [ABSTRACT FROM AUTHOR]

Functional abdominal pain or functional abdominal pain syndrome (FAPS) is an uncommon functional gut disorder characterised by chronic or recurrent abdominal pain attributed to the gut but poorly related to gut function. It is associated with abnormal illness behaviour and patients show psychological morbidity that is often minimised or denied in an attempt to discover an organic cause for symptoms. Thus the conventional biomedical approach to the management of such patients is unhelpful and a person's symptom experience is more usefully investigated using a biopsychosocial evaluation, which necessarily entails a multidisciplinary system of healthcare provision. Currently the pathophysiology of the disorder is poorly understood but is most likely to involve a dysfunction of central pain mechanisms either in terms of attentional bias, for example, hypervigilance or a failure of central pain modulation/inhibition. Although modern neurophysiological investigation of patients is promising and may provide important insights into the pathophysiology of FAPS, current clinical management relies on an effective physician-patient relationship in which limits on clinical investigation are set and achievable treatment goals tailored to the patient's needs are pursued. [ABSTRACT FROM AUTHOR]

This article focuses on the brain imaging. The two main brain imaging techniques discussed in this article are functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). PET relies on the principle of detecting positron emitting radionuclides that are intravenously injected into a subject positioned so that the head is placed in a specialized detection system. fMRI produces images of active brain regions by detecting indirect effects of neural activity of local blood flow, volume, and oxygen saturation, giving detailed information regarding the functional neuroanatomy of the brain.

Background and aims: This study assessed whether childhood and current adversities: (a) were more prevalent in patients with functional dyspepsia (FD) or non-cardiac chest pain (NCCP) than in patients with gastro-oesophageal reflux disease (GORD) or ischaemic heart disease (IHD); and (b) predicted health related quality of life in these disorders. Patients: Cohort study of consecutive attenders to gastroenterology and cardiology clinics in a secondary tertiary referral centre. Methods: Patients were interviewed using the childhood experience of care and abuse and life events and difficulties schedules. Distress was assessed by questionnaire. Outcome was assessed using SF36 at the index clinic visit and six months later. Results: A total of 133 patients were included (40 NCCP, 43 FD, 29 GORD, and 21 IHD) (67% response rate). The diagnostic groups did not differ significantly in the proportion reporting childhood adversity (30%), ongoing social stress (40%), lack of a close confidant (14%), or level of psychological distress. Reported childhood adversity was associated with poor outcome at the index visit (SF36 physical component score: 36.6 (SEM 1 .8) v 42.3 (SEM 1.2) for the remainder; p = 0.014). In multiple regression analysis, childhood adversity was a significant independent predictor for patients with functional disorders (NCCP and FD) but not organic disorders (GORD or IHD). Change in SF36 score at six months was determined by age and distress score at the index visit in both groups. Conclusion: Childhood adversity was common among this consecutive sample but was associated directly with poor outcome only in patients with functional gastrointestinal syndromes. Distress is an important predictor of outcome in all patients. Greatest impairment occurs when lack of social support accompanies reported childhood adversity. [ABSTRACT FROM AUTHOR]

Background: While cortical processing of visceral sensation has been described, the role that cognitive factors play in modulating this processing remains unclear. Aim: To investigate how selective and divided attention modulate the cerebral processing of oesophageal sensation. Methods: In seven healthy volunteers (six males, mean age 33 years; ranging from 24 to 41 years old) from the general community, phasic visual and oesophageal (non-painful balloon distension) stimuli were presented simultaneously. During the selective attention task, subjects were instructed to press a button either to a change in frequency of oesophageal or visual stimuli. During a divided attention task, subjects received simultaneous visual and oesophageal stimuli and were instructed to press a button in response to a change in frequency of both stimuli. Results: Selectively Focussing attention on oesophageal stimuli activated the visceral sensory and cognitive neural networks (primary and secondary sensory cornices and anterior cingulate cortex respectively) while selective attention to visual stimuli primarily activated the visual cortex. When attention was divided between the two sensory modalities, more brain regions in the sensory and cognitive domains were utilised to process oesophageal stimuli in comparison to those employed to process visual stimuli (p =0.003). Conclusion: Selective and divided attention to visceral stimuli recruits more neural resources in both the sensory and cognitive domains than attention to visual stimuli. We provide neurobiological evidence that demonstrates the biological importance placed on visceral sensations and demonstrate the influence of cognitive factors such as attention on the cerebral processing of visceral sensation. [ABSTRACT FROM AUTHOR]

The role of long‐term parenteral support in patients with underlying benign conditions who do not have intestinal failure (IF) is contentious, not least since there are clear benefits in utilising the oral or enteral route for nutritional support. Furthermore, the risks of long‐term home parenteral nutrition (HPN) are significant, with significant impacts on morbidity and mortality. There has, however, been a recent upsurge of the use of HPN in patients with conditions such as gastro‐intestinal neuromuscular disorders, opioid bowel dysfunction, disorders of gut–brain interaction and possibly eating disorders, who do not have IF. As a result, the European Society of Clinical Nutrition and Metabolism (ESPEN), the European Society of Neuro‐gastroenterology and Motility (ESNM) and the Rome Foundation for Disorders of Gut Brain Interaction felt that a position statement is required to clarify – and hopefully reduce the potential for harm associated with – the use of long‐term parenteral support in patients without IF. Consensus opinion is that HPN should not be prescribed for patients without IF, where the oral and/or enteral route can be utilised. On the rare occasions that PN commencement is required to treat life‐threatening malnutrition in conditions such as those listed above, it should only be prescribed for a time‐limited period to achieve nutritional safety, while the wider multi‐disciplinary team focus on more appropriate biopsychosocial holistic and rehabilitative approaches to manage the patient's primary underlying condition. [ABSTRACT FROM AUTHOR]

Describes the use of magnetic stimulation of the human motor cortex and the extracranial vagus nerve in the neck to study human esophageal electromyographic (EMG) responses. Esophageal myoelectric and manometric responses; Esophageal EMG paterns between stimulations; Effect of Valsalva maneuver.

The cover image, created by Faaria Khan and Dania Khan, is based on the Original article, The association between Ehlers‐Danlos syndrome—hypermobility type and gastrointestinal symptoms in university students: a cross‐sectional study, by QASIM AZIZ et al., DOI 10.1111/nmo.12942. [ABSTRACT FROM AUTHOR]