Abnormal visceral perception in patients with functional dyspepsia: use of cerebral potentials evoked by electrical stimulation of the oesophagus

Modification of rectal function and emotion by repetitive transcranial magnetic stimulation in humans

Gut microbiota may affect function of the dorsolateral prefrontal cortex (DLPFC). However, there have been a few studies on modification of brain-gut interactions with repetitive transcranial magnetic stimulation (rTMS) to the DLPFC. We hypothesized that stimulation of the right or left DPFC by rTMS modifies the brain-gut interactions in humans. Subjects were 25 healthy males. Viscerosensory evoked potential (VEP) with sham (0 mA) or actual (30 mA) electrical stimulation (ES) of the rectum was taken after sham, low frequency rTMS at 0.1 Hz, and high frequency rTMS at 10 Hz to the right or left DLPFC. Rectal tone was measured with a rectal barostat. Visceral perception and emotion were analyzed using ordinates scale, rectal barostat, and viscerosensory evoked potential. Low frequency rTMS to the right DLPFC significantly reduced the visceral sensation and emotion composite score evoked by ES at 30 mA (p < 0.05). Plasma ACTH was significantly increased by high frequency rTMS to the right or left DLPFC (p < 0.05). Rectal fine contractions were significantly induced by low frequency rTMS to the right or left DLPFC and high frequency rTMS to the right DLPFC (p < 0.05). These results suggest that stimulation of the right or left DPFC by rTMS modifies the brain-gut interactions in humans.

Brain responses to cardiac electrical stimulation: a new EEG method for evaluating cardiac sensation

Although cardiac sensation, such as palpitation or chest pain, is common and is sometimes a malignant sign of heart diseases, the mechanism by which the human brain responds to afferent signals from the heart remains unclear. In this study, we investigated whether electrical stimulation of the heart provokes brain responses in humans. We examined 15 patients (age: 65.4 ± 3.1 years old, 11 males and 4 females) implanted with either a cardiac pacemaker or cardiac resynchronization therapy (CRT) device. Electroencephalogram (EEG) was simultaneously recorded from the vertex during right ventricular pacing at 70-100 beats/min at baseline (1.5 V) and intense (6-8 V) stimulation sessions. We evaluated brain responses to cardiac electrical stimulation by measuring cerebral potentials that were obtained by subtracting the average of 100 EEG waves triggered by cardiac pacing during baseline stimulation from those during the intense stimulation. Intense stimulation of the cardiac pacemaker or CRT device reproducibly induced cardiac sensation in 6 out of the 15 patients; namely, the remaining 9 patients showed no reproducible response. Brain responses were evident by averaging cerebral potentials from all of the 15 patients and those from 6 patients with reproducible cardiac sensation. To the best our knowledge, this is the first report that demonstrates the brain responses to cardiac electrical stimulation in humans. This new method should be useful for examining pathophysiology of cardiac diseases with pathological cardiac sensation, including cardiac anxiety and silent myocardial ischemia.

Effect of repetitive transcranial magnetic stimulation on rectal function and emotion in humans

BACKGROUND

A previous brain imaging study demonstrated activation of the right dorsolateral prefrontal cortex (DLPFC) during visceral nociception, and this activation was associated with anxiety. We hypothesized that functional modulation of the right DLPFC by repetitive transcranial magnetic stimulation (rTMS) can reveal the actual role of right DLPFC in brain-gut interactions in humans.

METHODS

Subjects were 11 healthy males aged 23.5 ± 1.4 (mean ± SE) years. Viscerosensory evoked potential (VEP) with sham (0 mA) or actual (30 mA) electrical stimulation (ES) of the rectum was taken after sham, low frequency rTMS at 0.1 Hz, and high frequency rTMS at 10 Hz to the right DLPFC. Rectal tone was measured with a rectal barostat. Visceral perception and emotion were analyzed using an ordinate scale, rectal barostat, and VEP.

KEY RESULTS

Low frequency rTMS significantly reduced anxiety evoked by ES at 30 mA (p < 0.05). High frequency rTMS-30 mA ES significantly produced more phasic volume events than sham rTMS-30 mA ES (p < 0.05).

CONCLUSIONS AND INFERENCES

We successfully modulated the gastrointestinal function of healthy individuals through rTMS to the right DLPFC. Thus, rTMS to the DLPFC appears to modulate the affective, but not direct, component of visceral perception and motility of the rectum.

Role of histaminergic neurons in hypnotic modulation of brain processing of visceral perception

Modulating visceral sensation of the body is important to the understanding of emotion formation. Molecules that act during hypnosis and modify visceral pain perception are not known. We tested our hypothesis that hypnotic suggestion changes electrophysiological processing of visceroafferent signals in the human brain and that these conditions are in part dependent on histaminergic neurons. Twelve healthy male subjects were studied on two separate days: a day of treatment with histamine H1 receptor antagonist (d-chlorpheniramine 100 microg kg(-1), intravenously) and another day of that with placebo (saline, the same amount) in a randomized order. We recorded cortical evoked potentials to 100 rectal electrical stimuli after neutral, hyperalgesic or analgesic hypnotic suggestions as given to modulate the visceral perception. Analgesic suggestion reduced the amplitude of the deepest positive peak of viscerosensory evoked potential. Administration of histamine H1 antagonist diminished the attenuation of viscerosensory evoked potential by analgesic suggestion. Our results suggest that central pain modulatory system in the brain is activated by hypnotic suggestion and that brain histamine is a mediator in the hypnotic modulation of visceral sensory pathway as well as in the control of consciousness level. These findings lead us to possible new treatment for control of visceral perception.

Comparison of clinical features and patient background in functional dyspepsia and peptic ulcer

To elucidate the clinical features of functional dyspepsia (FD), patients with FD were compared with patients with peptic ulcer. Fifty-eight FD and fifty-nine peptic ulcer patients were compared with respect to clinical features and patient background. In the FD group, symptoms of dyspepsia, especially upper abdominal fullness and nausea, were more common than in the peptic ulcer group. The FD group complained greater distress (severity of the most distressing symptom; P < .001) and showed higher State-Trait Anxiety Inventory (STAI) scores (trait-anxiety score; P < .05). A higher proportion of FD patients had consulted another physician (P < .01). Even when subjects from the FD and peptic ulcer group in this study were matched for age and gender and compared with respect to these variables, almost the same characteristics were seen. These results indicate that FD markedly decreases quality of life in a variety of aspects.

Pain in chronic pancreatitis: the role of reorganization in the central nervous system

BACKGROUND & AIMS

In various chronic pain conditions cortical reorganization seems to play a role in the manifestations. The aim of this study was to investigate cortical reorganization in patients with pain caused by chronic pancreatitis.

METHODS

Twelve healthy subjects and 10 patients with chronic pancreatitis were included. The esophagus, stomach, and duodenum were stimulated electrically at the pain threshold using a nasal endoscope. The electroencephalogram was recorded from 64 surface electrodes and event-related brain potentials (EPs) were obtained.

RESULTS

As compared with healthy subjects, the patient group showed decreased latencies of the early EP components (N1, P < .001; P1, P = .02), which is thought to reflect the exogenous brain pain processing specifically. Source analysis showed that the dipolar activities corresponding to the early EPs were located consistently in the bilateral insula, in the anterior cingulate gyrus, and in the bilateral secondary somatosensory area. The bilateral insular dipoles were localized more medial in the patient group than in the healthy subjects after stimulation of all 3 gut segments (P < .01). There also were changes in the cingulate cortex where the neuronal source was more posterior in patients than in controls to stimulation of the esophagus (P < .05).

CONCLUSIONS

The findings indicate that pain in chronic pancreatitis leads to changes in cortical projections of the nociceptive system. Such findings also have been described in somatic pain disorders, among them neuropathic pain. Taken together with the clinical data this suggests a neuropathic component in pancreatic pain, which may influence the approach to treatment.

Acid in the duodenum

Acid in the duodenum triggers many physiological responses. Also, acid in the duodenum elicits hyperalgesia of the foregut. In the article by Hobson et al. in this issue the reduction of the latencies in evoked potential in response to electrical stimulation of the esophagus after duodenal acidification is reported, which may explain the symptom development in functional dyspepsia. Microscopic damages of the duodenal epithelium might be responsible for such changes. Microscopic damages of the intestinal epithelium may come into the center stage of the pathogenesis of functional GI disorders.

Functional dyspepsia: motor abnormalities, sensory dysfunction, and therapeutic options

Functional dyspepsia is a common condition, but as yet, the underlying etiology is unclear. In this article, upper gastrointestinal motor and sensory physiology are reviewed and the current evidence for motor and/or sensory functional abnormalities causing dyspeptic symptoms is presented. The complex interrelationship between abnormal motor activity and sensation is explored, as well as the potential roles for autonomic dysfunction and psychological state in modulating gastrointestinal sensation and motor function. Finally, based on clinical trial evidence, a treatment pathway for functional dyspepsia is suggested.

A dose-ranging, placebo-controlled, randomized trial of alosetron in patients with functional dyspepsia

BACKGROUND

Functional dyspepsia is characterized by upper abdominal pain or discomfort.

AIM

To assess the benefit of the 5-HT3-receptor antagonist alosetron in a pilot, dose-ranging, placebo-controlled, multicentre, randomized clinical trial.

METHODS

A total of 320 functional dyspepsia patients received placebo (n=81), or alosetron 0.5 mg b.d. (n=77), 1.0 mg b.d. (n=79) or 2.0 mg b.d. (n=83) for 12 weeks, followed by 1 week of follow-up. Primary efficacy was the 12-week average rate of adequate relief of upper abdominal pain or discomfort. Secondary endpoints assessed pain and upper gastrointestinal symptoms.

RESULTS

Twelve-week average rates of adequate relief of pain or discomfort were 46% (95% CI: 37-54%), 55% (95% CI: 46-63%), 55% (95% CI: 47-64%) and 47% (95% CI: 38-55%) in the placebo, 0.5 mg, 1.0 mg and 2.0 mg alosetron groups, respectively. Alosetron 0.5 mg or 1.0 mg showed potential benefit over placebo for early satiety and postprandial fullness. Females showed greater responses compared to males. Patients with adequate relief had significantly (P < 0.001) greater reductions in severity and frequency of functional dyspepsia symptoms than those without adequate relief. Constipation was the most commonly reported adverse event.

CONCLUSIONS

Alosetron showed potential benefit in relieving functional dyspepsia symptoms compared to placebo. Patients with adequate relief of upper abdominal pain or discomfort showed improvements in multiple functional dyspepsia symptoms.

Nonulcer dyspepsia

New definitions of functional disorders in general and nonulcer dyspepsia in particular were published in the period of review. Although the definition of functional dyspepsia as persistent or recurrent unexplained upper abdominal pain or discomfort stayed essentially the same, new definitions of dyspepsia subgroups were introduced based on the predominant symptom; a reflux-like dyspepsia subgroup was not supported. It is hoped that these criteria, derived by a consensus among international experts in the field, will improve the reliability and the interpretability of future epidemiologic and interventional studies. A wide range of studies dealt with the role of putative etiological factors in functional bowel disorders including Helicobacter pylori, altered visceral sensation, or upper intestinal motility. Although eradication of H. pylori does not seem to relieve dyspepsia over placebo in recent studies of nonulcer dyspepsia, eradication of H. pylori has generally been advised because of suspected beneficial long-term effects (eg, treatment of misdiagnosed ulcer disease) that probably overweigh the potential risks.