Involvement of autonomic nervous activity changes in gastroesophageal reflux in neonates during sleep and wakefulness

Modifiable risk factors mediate the effect of gastroesophageal reflux disease on stroke and subtypes: A Mendelian randomization study

OBJECTIVES

Previous observational studies have suggested that gastroesophageal reflux disease (GERD) increases the risk of stroke, but the specific underlying mechanisms are unclear. We investigated the causal associations of GERD with stroke and its subtypes using Mendelian randomization (MR), and evaluated the potential mediating effects of modifiable stroke risk factors in the causal pathway.

METHODS

Genetic instrumental variables for GERD were extracted from the latest genome-wide association study (GWAS) summary level data. We initially performed two-sample MR to examine the association of GERD with stroke and its subtypes, including ischemic stroke, intracranial hemorrhage, and the major subtypes of ischemic stroke. Two-step MR was further employed to investigate the mediating effect of 15 risk factors in the causal pathway.

RESULTS

We found significant causal associations of genetically predicted GERD with increased risk of stroke (OR: 1.22 95% CI: 1.126-1.322), ischemic stroke (OR: 1.19 95% CI: 1.098-1.299), and large-artery stroke (OR: 1.49 95% CI: 1.214-1.836). Replication and sensitivity analyses yielded consistent effect directions and similar estimates. Further mediation analyses indicated that hypertension (HTN), systolic blood pressure (SBP), and type 2 diabetes (T2D) mediated 36.0%, 9.0%, and 15.8% of the effect of GERD on stroke; 42.9%, 10.8%, and 21.4% for ischemic stroke, and 23.3%; 7.9%, and 18.7% for large-artery stroke, respectively.

CONCLUSIONS

This study supports that GERD increases susceptibility to stroke, ischemic stroke, and large-artery stroke, and is partially mediated by HTN, SBP, and T2D.

Change of Sleep Stage during Gastroesophageal Reflux in Infants

INTRODUCTION

This study intended to explore the existence of a temporal association of changes of sleep stage and gastroesophageal reflux (GER) in infants.

MATERIALS AND METHODS

Documentation of sleep stage and GER was conducted via the use of synchronized polygraphic recording combined with impedance-pH-metry in 15 infants. The total recording-time (Rt) was divided into GER-"window-time" (five seconds before and after the onset of a GER episode), "remaining GER time", and "GER-free time", and analyzed for changes of sleep stage.

RESULTS

a total of 462 GER episodes were identified during Rt (151.1 h) in all infants. During 1.3 h of window-time; 61 changes of sleep stage (47/h); during 5.9 h of Remaining GER-time, 139 changes of sleep stage (24/h); and during 143.9 h of GER-free time, 4087 changes of sleep stage (28/h) were documented. Change of sleep stage was strongly associated with the onset of GER (p < 0.02 and p < 0.05, respectively).

CONCLUSIONS

There is a strong temporal association between sleep irregularities, i.e., changes of sleep and episodes of GER in infants. When dealing with disturbed sleep in infants, GER should be considered by caregivers.

Neuromodulation for functional upper gastrointestinal diseases

Neuromodulation has recently received a great deal of attention among academic institutions, government funding agents and industries. This mini-review focuses on methods and applications as well as mechanisms of various neuromodulation methods in treating functional diseases of the upper gastrointestinal tract. First, the methods of various neuromodulation are introduced, including direct electrical stimulation at various peripheral nerves, such as the vagus nerve, sacral nerve and spinal cord, direct gastrointestinal electrical stimulation and noninvasive/transcutaneous electrical stimulation. Then, literature search was performed on the clinical applications of these neuromodulation methods for treating gastroesophageal reflux disease, functional dyspepsia and gastroparesis. Due to nature of the mini-review, the search results are selectively presented based on the expert opinions. Finally, a perspective is provided based on the author's own experience in this field of research.

Roles of Heart Rate Variability in Assessing Autonomic Nervous System in Functional Gastrointestinal Disorders: A Systematic Review

Functional gastrointestinal disorders (FGID) and gastroesophageal reflux (GERD) disease affect a large global population and incur substantial health care costs. Impairment in gut-brain communication is one of the main causes of these disorders. The central nervous system (CNS) provides its inputs to the enteric nervous system (ENS) by modulating the autonomic nervous system (ANS) to control the gastrointestinal functions. Therefore, GERD and FGID's might be associated with autonomic dysfunction, which can be identified via heart rate variability (HRV). FGIDs may be treated by restoring the autonomic dysfunction via neuromodulation. This article reviews the roles of HRV in the assessment of autonomic function and dysfunction in (i) gastroesophageal reflux (GERD), and the following FGIDs: (ii) functional dyspepsia (FD) and gastroparesis, (iii) irritable bowel syndrome (IBS) and (iv) constipation. The roles of HRV in the assessment of autonomic responses to various interventions were also reviewed. We used PUBMED, Web of Science, Elsevier/Science direct and Scopus to search the eligible studies for each disorder, which also included the keyword 'heart rate variability'. The retrieved studies were screened and filtered to identify the most suitable studies using HRV parameters to associate the autonomic function with any of the above disorders. Studies involving both human and animal models were included. Based on analyses of HRV, GERD as well as the FGIDs were found to be associated with decreased parasympathetic activity and increased sympathetic nervous system activity with the autonomic balance shifted towards the sympathetic nervous system. In addition, the HRV methods were also reported to be able to assess the autonomic responses to various interventions (mostly neuromodulation), typically the enhancement of parasympathetic activity. In summary, GERD and FGIDs are associated with impaired autonomic dysfunction, mainly due to suppressed vagal and overactive sympathetic tone, which can be assessed noninvasively using HRV.

Correlation Between Refractory Laryngopharyngeal Reflux Disease and Symptoms of Anxiety and Depression

BACKGROUND AND STUDY AIMS

The occurrence, development, and prognosis of refractory laryngopharyngeal reflux disease (LPRD) may be related to anxiety and depression. Our study aims to investigate anxiety and depressive symptoms in LPRD and clarify the correlations among them.

PATIENTS AND METHODS

Twenty-eight patients were diagnosed with LPRD and subsequently referred to the Department of Mental Health for treatment. The patients were divided into the Self-rating Anxiety Scale (SAS)/Self-rating Depression Scale (SDS) positive group (+) and the SAS/SDS negative group (-). All patients were treated (oral administration) with a standard dose of proton pump inhibitor (PPI, omeprazole 20 mg bid) plus one tablet of Deanxit (flupentixol-melitracen) after breakfast. Treatment efficacy was evaluated after one month of drug treatment. The therapeutic effect of PPI treatment alone was compared with that treated with PPI + Deanxit.

RESULTS

Among 28 patients with refractory LPRD, the main reflux symptoms and signs were specific. There were differences in gender distribution and age distribution among the 28 patients with refractory LPRD, and there were 17 patients (60.7%) in the SAS/SDS (+) group and 11 patients in the SAS/SDS (-) group (39.3%). Regarding efficacy evaluation after one month of PPI + Deanxit treatment, the differences in indices before and after treatment were statistically significant (all p<0.05).

CONCLUSION

Anxiety and depressive symptoms influence the occurrence, development, and treatment efficacy of refractory LPRD. Attention to and targeted treatment of anxiety and depressive symptoms can help improve the treatment outcomes of patients with refractory LPRD.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Coupling of autism genes to tissue-wide expression and dysfunction of synapse, calcium signalling and transcriptional regulation

Autism Spectrum Disorder (ASD) is a heterogeneous disorder that is often accompanied with many co-morbidities. Recent genetic studies have identified various pathways from hundreds of candidate risk genes with varying levels of association to ASD. However, it is unknown which pathways are specific to the core symptoms or which are shared by the co-morbidities. We hypothesised that critical ASD candidates should appear widely across different scoring systems, and that comorbidity pathways should be constituted by genes expressed in the relevant tissues. We analysed the Simons Foundation for Autism Research Initiative (SFARI) database and four independently published scoring systems and identified 292 overlapping genes. We examined their mRNA expression using the Genotype-Tissue Expression (GTEx) database and validated protein expression levels using the human protein atlas (HPA) dataset. This led to clustering of the overlapping ASD genes into 2 groups; one with 91 genes primarily expressed in the central nervous system (CNS geneset) and another with 201 genes expressed in both CNS and peripheral tissues (CNS+PT geneset). Bioinformatic analyses showed a high enrichment of CNS development and synaptic transmission in the CNS geneset, and an enrichment of synapse, chromatin remodelling, gene regulation and endocrine signalling in the CNS+PT geneset. Calcium signalling and the glutamatergic synapse were found to be highly interconnected among pathways in the combined geneset. Our analyses demonstrate that 2/3 of ASD genes are expressed beyond the brain, which may impact peripheral function and involve in ASD co-morbidities, and relevant pathways may be explored for the treatment of ASD co-morbidities.

Association between Reflux Esophagitis Incidence and Palmar Hyperhidrosis

The autonomic dysfunction in palmar hyperhidrosis (PH) includes not only sympathetic overactivity but also parasympathetic impairment. A decrease of parasympathetic tone has been noted in gastroesophageal reflux disease of neonates and adults. Patients with reflux esophagitis have a defective anti-reflux barrier. The association between reflux esophagitis and PH is deliberated in this article. The National Health Insurance Database in Taiwan was used. At first-time visits, PH patients were identified by the International Classification of Disease, 9th Revision, Clinical Modification disease code of 780.8 without endoscopic thoracic sympathectomy. Patients were matched by age and gender as control groups. The reflux esophagitis incidence was assessed using disease codes 530.11, 530.81, and 530.85. The factors related to reflux esophagitis were established by the Cox proportional regression model. The risk of reflux esophagitis in PH patients had a hazard ratio of 3.457 (95% confidence interval: 3.043-3.928) after adjustment of the other factors. We confirmed the association between reflux esophagitis and PH. Health care providers must be alerted to this relationship and other risk factors of reflux esophagitis to support suitable treatments to improve the quality of life of patients.

Association between laryngopharyngeal reflux disease and autonomic nerve dysfunction

PURPOSE

To assess autonomic nerve function in patients with laryngopharyngeal reflux disease (LPRD) and determine the correlation between LPRD and autonomic nerve dysfunction.

METHODS

Patients with suspected LPRD who visited our outpatient department were assessed using the reflux symptom index (RSI) and reflux finding score (RFS) scales. Eighty-one suspected LPRD patients with RSI > 13 and RFS > 7 were examined using 5-min short-range heart rate variability, and all were given proton pump inhibitor diagnostic treatment.

RESULTS

The root mean square of successive R-R intervals, high-frequency (HF) power, standardized HF, and HF % were significantly lower in the case group than in the control group (p < 0.05); however, the low frequency (LF)/HF ratio was significantly higher in the case group (p < 0.05). There were no significant differences in the standard deviation of the average normal-to-normal interval, total power, LF power, and LF % between the two groups (p > 0.05). RSI, RFS, and disease duration were negatively correlated with HF power (r = - 0.89, -0.77, and -0.315, respectively; p < 0.05). The LF/HF ratio and disease duration were positively correlated (r = 0.315, p < 0.05).

CONCLUSIONS

Autonomic nerve dysfunction was observed in our patients with LPRD. LPRD severity was significantly correlated with autonomic nerve dysfunction and negatively correlated with vagal nerve function.

Effects of Smoking Exposure in Infants on Gastroesophageal Reflux as a Function of the Sleep-Wakefulness State

OBJECTIVE

To determine whether perinatal smoking exposure is associated with gastroesophageal reflux (GER)-related changes in sleep-wakefulness states in neonates.

STUDY DESIGN

Thirty-one neonates, referred for the investigation of suspected GER, were recruited and underwent multichannel impedance-pH monitoring and synchronized 8- to 12-hour polysomnography. The infants' exposure to tobacco smoke was estimated by means of a urine cotinine assay. The total number, frequency (h^-1), and mean duration (minutes) of GER-pH (reflux events detected by the pH electrode only) and GER-imp (reflux events with bolus movement detected by impedance) events were determined. Intergroup differences (smoking-exposed group vs nonexposed group) were probed with nonparametric, unpaired Mann-Whitney U tests. A χ² test was used to assess a possible intergroup difference in bolus retrograde migration during GER-imp events.

RESULTS

According to the urine cotinine assay, 21 of the 31 neonates had been exposed to cigarette smoke during the perinatal period. The number (and frequency) of GER-imp was significantly greater (P = .016) in the exposed group (29 [0-90]) than in the nonexposed group (12 [2-35]). Migration of the esophageal bolus from the distal segment to the most proximal segment was significantly more frequent (P = .016) in the exposed group (83% of GER) than in the nonexposed group (41%). The GER pattern associated with smoking exposure was particularly obvious during Rapid eye movement sleep.

CONCLUSIONS

The more frequent occurrence and greater proximal migration of GER-imp in the smoking-exposed group (especially during rapid eye movement sleep) may have clinical relevance. Smoking exposure is a preventable risk factor for limiting the occurrence of GER in neonates.

Gastroesophageal reflux is not associated with short-term variability of parasympathetic activity in children

PURPOSE

A lower parasympathetic activity was described in patients with the gastroesophageal reflux disease. We aimed to determine whether gastroesophageal reflux (GER) episodes are associated with a short-term parasympathetic tone variability in children.

METHODS

In order to address this question we performed simultaneous 24-h esophageal multichannel intraluminal impedance-pH and electrocardiographic monitoring in 16 children (age range 6-18 years), including 8 with asthma and 2 with gastroesophageal reflux disease. After describing duration, height, and acidity of 483 GER episodes we also measured parasympathetic-related heart rate variability parameters in 4 time periods: preceding, containing, following GER, and in-between GERs (control). High frequency (HF) power and root-mean square differences of successive R-R intervals (r-MSSD) were assessed in 2.5-min and 1-min periods, respectively.

RESULTS

We did not identify the searched short-term parasympathetic tone changes.

CONCLUSIONS

In conclusion, GER episodes and their characteristics were not associated with short-term variability of parasympathetic activity in children.

Genetics of enteric neuropathies

Abnormal development or disturbed functioning of the enteric nervous system (ENS), the intrinsic innervation of the gastrointestinal tract, is associated with the development of neuropathic gastrointestinal motility disorders. Here, we review the underlying molecular basis of these disorders and hypothesize that many of them have a common defective biological mechanism. Genetic burden and environmental components affecting this common mechanism are ultimately responsible for disease severity and symptom heterogeneity. We believe that they act together as the fulcrum in a seesaw balanced with harmful and protective factors, and are responsible for a continuum of symptoms ranging from neuronal hyperplasia to absence of neurons.

Relationship between gastroesophageal reflux disease and psychological factors and autonomic nervous function

Gastroesophageal reflux disease (GERD) is a multifactorial disease. Psychological factors play an important role in the development and progression process and the treatment of GERD. Autonomic nervous dysfunction leads to changes of the digestive tract and high gastrointestinal sensitivity. Autonomic nerve function disorder is the intermediate link between psychological factors and gastroesophageal reflux symptoms in patients with GERD. Research on psychological factors and autonomic nervous function plays an important role in the clinical diagnosis and treatment of GERD in the future.