Autonomic nervous system function in young children with functional abdominal pain or irritable bowel syndrome

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.

Systematic Review of Autonomic Nervous System Functioning in Pediatric Chronic Pain

OBJECTIVES

Chronic pain is a common and debilitating health problem that impacts up to one third of children and adolescents. The pathophysiological mechanisms of chronic pain are complex, but considerable research links dysfunction of the autonomic nervous system (ANS) and chronic pain in adults. No review of ANS functioning has been conducted in pediatric chronic pain. We systematically reviewed studies examining ANS activity among youth with primary chronic pain conditions.

METHODS

A systematic search of PsycINFO, PubMed, and CINAHL was conducted using specific search terms. Articles were included if studies measured heart rate, blood pressure, heart rate variability, galvanic skin responses, or pupillometry among children or adolescents with a chronic pain condition. Studies examining these factors in the context of a specific disease-related pain condition were excluded.

RESULTS

Of the 1304 articles screened, 15 studies met the criteria for inclusion in this review. All included studies were cross-sectional and primarily included youth with abdominal pain. Results revealed preliminary evidence of reduced parasympathetic activity among youth with pain as measured by heart rate variability. However, results were mixed across ANS indices. Measurement and procedural differences, in addition to a lack of control groups in some studies, limit the interpretability of the reviewed findings.

DISCUSSION

Additional studies with larger and more diverse samples of youth with various chronic primary pain conditions are needed to delineate possible relationships among ANS functioning and the development and maintenance of chronic pain in children and adolescents. Clinical implications and avenues for future research are discussed.

Autonomous nervous system regulation of pain in children with cerebral palsy

Aim: Children with cerebral palsy (CP) have increased pain sensitivity and recurrent pain episodes; however, pain is underreported in children with intellectual impairment. Cardiac autonomic regulation is imbalanced in chronic pain conditions and neurological disorders. This study aims at exploring the autonomous nervous system regulation of pain in children with CP compared with typically developing peers (TDP).Method: Heart rate variability (HRV) was recorded during 24 hours in 26 children with CP and 26 TDP, and examined offline at baseline (sleeping, seated rest) and during spontaneous pain events. Pain and fatigue, HRV indices (linear indices on time - IBI, SDNN, RMSSD - and frequency domains - high, low, and very low frequency - and non-linear indices - Hurst coefficient and multiscale entropy) were computed.Results: Children with CP showed comparable HRV during daily conditions and similar reductions after pain events than their TDP, regardless of their level of intellectual impairment. Interpretation: Children with CP have an intact autonomic regulation in acute pain events. HRV could be an accurate pain biomarker in children with CP and intellectual disability.What this paper adds: Autonomic regulation in acute pain is efficient in children with cerebral palsy.Heart rate variability indices can be reliable pain biomarkers in intellectual impairment.

A cross-sectional study of nausea in functional abdominal pain: relation to mucosal mast cells and psychological functioning

Background

Nausea is a common symptom in youth with chronic abdominal pain. The aims of the current study were to assess: 1) the frequency of nausea in patients with functional dyspepsia (FD) and irritable bowel syndrome (IBS), respectively, as defined by Rome IV criteria; and, 2) relationships between nausea and mucosal inflammation as defined by antral and duodenal eosinophil and mast cell densities. A secondary aim was to assess relationships between nausea and other gastrointestinal symptoms, non-gastrointestinal somatic symptoms, and psychological dysfunction.

Methods

Records from patients with pain associated functional gastrointestinal disorders were retrospectively reviewed for gastrointestinal and somatic symptoms and anxiety, depression, and somatizations scores as assessed by the Behavior Assessment System for Children (BASC-2). In addition, previous gastric and mucosal biopsies were assessed for mast cell and eosinophil densities, respectively.

Results

250 patients, ages 8 to 17 years, were assessed. Nausea was reported by 78% and was equally prevalent in those with FD alone, those with IBS alone, and those with both FD and IBS. Nausea was associated with increased mean (21.4 vs. 17.5) and peak (26.2 vs. 22.9) duodenal mast cell densities as compared those without nausea. Nausea was also associated with a wide variety of individual gastrointestinal symptoms, as well as headaches, fatigue, and dizziness. Lastly, nausea was associated with elevated self-report scores for anxiety (55.2 vs. 50.0), depression (50.2 vs. 46.1), and somatization (70.3 vs. 61.8).

Conclusions

Nausea is common in children and adolescents with pain-associated FGIDs as defined by Rome IV and is not unique to either FD or IBS. Nausea is associated with increased mucosal mast cell density, non-gastrointestinal somatic symptoms, and psychologic dysfunction.

Heart Rate Variability and Gastric Electrical Response to a Cold Pressor Task in Youth with Functional Dyspepsia

BACKGROUND/AIMS

While stress has been implicated in functional dyspepsia (FD), the mechanisms by which stress results in symptoms are not well defined. The aim of the current study was to assess gastric myoelectric and autonomic changes in response to a physical stressor in youth with FD.

METHODS

In a group of healthy controls and pediatric FD subjects, we recorded ECG and EGG signals 30 min before and 60 min after, a cold pressor task (CPT). Gastric EGG and heart rate variability (HRV) parameters were calculated in pre- and post-CPT stages and in short intervals.

RESULTS

The pre-CPT percent tachygastria was higher in FD subjects as compared to controls. However, CPT did not induce any EGG changes in either controls or FD subjects and the two groups did not differ from each other post-CPT. The CPT resulted in an increase in HRV and standard deviation of NN intervals in controls; there was no change in any HRV parameter in FD subjects.

CONCLUSIONS

Acute physical stress does not appear to induce gastric electrical abnormalities in youth with FD. Youth with FD appear to lack the normal flexible autonomic response to a physical stressor.

Cardiovagal modulation in pediatric functional gastrointestinal disorders

BACKGROUND AND OBJECTIVES

Though reduced cardiovagal modulation accompanies adult IBS, adolescents with functional gastrointestinal disorders (FGID) have not been studied. We aim to investigate whether adolescents with FGID have reduced cardiovagal modulation.

METHODS

After 10-minute supine rest, we recorded ECG for 5-minute supine and 5-minute standing without support in healthy and FGID-affected adolescents. After analysis with Kubios 2.2 for high-frequency (hf) and low-frequency (lf) heart rate variability (HRV), Wilcoxon signed-ranks test compared individual paired supine and standing HRV data, while Kruskal-Wallis and Mann-Whitney U tests compared HRV across groups.

RESULTS

A total of 50 FGID subjects (90% females; median age 17 years [range 11-21]) and 22 healthy comparison group (HC) (59% females; median age 14 years [range 10-18]) participated. Both absolute and relative supine hfHRV exceeded standing in both groups. Absolute supine lfHRV was higher than standing in FGID patients and not in HCs, while relative supine lfHRV power was actually lower in both groups. Compared to HC, FGID group showed significantly lower absolute HRV, while relative HRV did not differ between groups.

CONCLUSIONS

Cardiovagal modulation is lower in adolescents with FGID. This difference impacts these subjects significantly. Whether this finding reflects a cause or a consequence of FGID is unknown.

Autonomic functions and gastric motility in children with functional abdominal pain disorders

BACKGROUND

Abdominal pain-predominant functional gastrointestinal disorders (AP-FGIDs) are the most common cause of recurrent abdominal pain in children. Despite its high prevalence, the underlying pathophysiology of this condition is poorly understood.

AIM

To assess the role of gastric dysmotility and autonomic nervous system dysfunction in the pathophysiology of AP-FGIDs.

METHODS

One hundred children, fulfilling Rome III criteria for AP-FGIDs, and 50 healthy controls, aged 5 to 12 years, were recruited after obtaining parental consent. All patients were investigated for underlying organic disorders. Gastric motility and cardiovascular autonomic functions were assessed using validated non-invasive techniques.

RESULTS

The main gastric motility parameters assessed (gastric emptying rate [45.7 vs 59.6 in controls], amplitude [48.7 vs 58.2], frequency of antral contractions [8.3 vs 9.4], and antral motility index [4.1 vs 6.4]) were significantly lower in children with AP-FGIDs (P < 0.05). The post-prandial antral dilatation at 1 min after the test meal significantly correlated with the severity of abdominal pain (P < 0.05). Assessment of autonomic functions in AP-FGID patients showed neither a significant difference compared to the control group, nor a correlation with gastric motility abnormalities (P > 0.05). The duration of pain episodes negatively correlated with the parasympathetic tone (maladaptive parasympathetic tone) (P < 0.05).

CONCLUSION

Children with AP-FGIDs have abnormal gastric motility but normal cardiovascular autonomic functions. There is no relationship between abnormal gastric motility and autonomic functions. The pathogenesis of AP-FGIDs is not related to cardiovascular autonomic dysfunction.

Functional abdominal pain disorders in children

Chronic abdominal pain is a common problem in pediatric practice. The majority of cases fulfill the Rome IV criteria for functional abdominal pain disorders (FAPDs). At times, these disorders may lead to rather serious repercussions. Area covered: We have attempted to cover current knowledge on epidemiology, pathophysiology, risk factors related to pathophysiology, clinical evaluation and management of children with FAPDs. Expert commentary: FAPDs are a worldwide problem with a pooled prevalence of 13.5%. There are a number of predisposing factors and pathophysiological mechanisms including stressful events, child maltreatment, visceral hypersensitivity, altered gastrointestinal motility and change in intestinal microbiota. It is possible that the environmental risk factors intricately interact with genes through epigenetic mechanisms to contribute to the pathophysiology. The diagnosis mainly depends on clinical evaluation. Commonly used pharmacological interventions do not play a major role in relieving symptoms. Centrally directed, nonpharmacological interventions such as hypnotherapy and cognitive behavioral therapy have shown both short and long term efficacy in relieving pain in children with FAPDs. However, these interventions are time consuming and need specially trained staff and therefore, not currently available at grass root level. Clinicians and researchers should join hands in searching for more pragmatic and effective therapeutic modalities to improve overall care of children with FAPDs.

Asymmetries in reciprocal baroreflex mechanisms and chronic pain severity: Focusing on irritable bowel syndrome

BACKGROUND

Objective measures of pain severity remain ill defined, although its accurate measurement is critical. Reciprocal baroreflex mechanisms of blood pressure (BP) control were found to impact differently on pain regulation, and thus their asymmetry was hypothesized to also connect to chronic pain duration and severity.

METHODS

Seventy-eight female patients with irritable bowel syndrome (IBS) and 27 healthy women were assessed for IBS severity and chronicity, negative affect, and various measures of resting autonomic function including BP, heart rate and its variability (HRV), baroreceptor-sensitivity to activations and inhibitions, gains of brady- and tachy-cardiac baro-responses, gains of BP falls/rises, and BP start points for these spontaneous baroreflexes.

KEY RESULTS

IBS directly and indirectly (through increased negative affect) was associated with asymmetry between baroreceptor activations/inhibitions compared to symmetrical baroreflex reciprocity in the healthy women. In the IBS group, independently of specific IBS symptoms, pain chronicity was associated with (i) decreased BP falls coupled with either (a) decreased tachycardia associated with lower disease severity (earlier "pain resilience" mechanism), or (b) decreased bradycardia associated with higher disease severity (later "pain decompensation" mechanism), or (ii) increased BP start point for baroreceptor activations coupled with either (a) BP increase (delayed "pain adaptation" mechanism) or (b) affect-related HRV decrease (delayed "pain aggravation" mechanism).

CONCLUSION AND INFERENCES

We anticipate the findings to be a starting point for validating these autonomic metrics of pain suffering and pain coping mechanisms in other chronic pain syndromes to suggest them as biomarkers of its severity and duration for profiling and correct management of chronic pain patients.

Effects of Cognitive Behavior Therapy on Heart Rate Variability in Young Females with Constipation-predominant Irritable Bowel Syndrome: A Parallel-group Trial

Background/Aims

The relation between heart rate variability (HRV) as non-invasive biomarkers of autonomic function and cognitive behavior therapy (CBT) as non-pharmacological treatments has rarely been examined in patients with constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study is to evaluate the efficacy of an 8-week CBT intervention on HRV and IBS symptoms, and the correlation of changes in HRV with changes in IBS symptoms among young female nursing students with IBS-C.

Methods

This study consisted of an exploratory subgroup analysis of 43 participants with IBS-C who had been randomly assigned to receive either 8 weeks of CBT (n = 23) or general medical information (control, n = 20). At baseline and 8, 16, and 24 weeks, participants completed a questionnaire assessing their gastrointestinal (GI) symptoms, anxiety, depression, and stress, and their HRV was measured via electrocardiography.

Results

At the 8-week follow-up, the high-frequency (HF) power was significantly higher, and the low-frequency (LF)/HF ratio was lower in the CBT group than in the control group (P < 0.001 for both), and the severity of GI symptoms (P = 0.003), anxiety (P < 0.001), depression (P < 0.001), and stress (P < 0.001) was significantly lower in the CBT group than in the control group. Changes in the HF power were significantly and inversely associated with changes in GI symptoms, anxiety, depression, and stress at 16 and 24 weeks (P < 0.05 for all; range of r from -0.37 to -0.68). Changes in the LF/HF ratio were also significantly and positively associated with changes in GI symptoms, anxiety, depression, and stress at 16 and 24 weeks (P < 0.05 for all; range of r from 0.38 to 0.60).

Conclusions

CBT was effective in managing symptoms in young IBS-C patients and the improvement of symptoms was sustained at 24 weeks following the completion of CBT. Furthermore, indirect measurement of autonomic function using HRV may be a useful objective parameter for assessing response to CBT in young IBS-C patients.

Childhood Irritable Bowel Syndrome Characteristics Are Related to Both Sex and Pubertal Development

OBJECTIVE

To determine the relationship of both pubertal development and sex to childhood irritable bowel syndrome (IBS) clinical characteristics including gastrointestinal symptoms (eg, abdominal pain) and psychological factors.

STUDY DESIGN

Cross-sectional study with children ages 7-17 years (n = 143) with a pediatric Rome III IBS diagnosis recruited from both primary and tertiary clinics between January 2009 and January 2014. Subjects completed 14-day prospective pain and stool diaries, as well as validated questionnaires assessing several psychological factors (somatization, depression, anxiety) and Tanner stage. Stool form ratings were completed using the Bristol Stool Form Scale.

RESULTS

Girls with higher Tanner scores (more mature pubertal development) had both decreased pain severity and pain interference; in contrast, boys with higher Tanner scores had both increasing pain severity (β = 0.40, P = .02) and pain interference (β = 0.16, P = .02). Girls (vs boys), irrespective of pubertal status, had both increased somatic complaints (P = .005) and a higher percentage (P = .01) of hard (Bristol Stool Form Scale type 1 or 2) stools. Pubertal status and sex did not significantly relate to IBS subtype, pain frequency, stooling frequency, anxiety, or depression.

CONCLUSIONS

In children with IBS, both pubertal development and/or sex are associated with abdominal pain severity, stool form, and somatization. These differences provide insight into the role of pubertal maturation during the transition from childhood to adult IBS.

Non-pharmacological management of abdominal pain-related functional gastrointestinal disorders in children

BACKGROUND

Abdominal pain-related functional gastrointestinal disorder (AP-FGID) comprises of 4 main conditions: functional dyspepsia, irritable bowel syndrome, abdominal migraine and functional abdominal pain. AP-FGIDs are diagnosed clinically based on the Rome IV criteria for FGIDs of childhood. There is limited evidence for pharmacological therapies.

DATA SOURCES

This review article discusses nonpharmacological management of AP-FGID based on the current literature including systematic reviews, randomized controlled trials, cohort and case control studies. We aim to provide a comprehensive overview on the available evidence for the pediatricians and pediatric gastroenterologists involved in managing children with AP-FGID.

RESULTS

Managing AP-FGIDs can be challenging. This should follow a stepwise approach with focused history, identification of "red flag" signs and symptoms, physical examination and investigations done following initial consultation. Family needs explaining that there is nothing seriously wrong with the child's abdomen. This explanation and reassurance can achieve symptom control in large number of cases. Non-pharmacological interventions are delivered through lifestyle and dietary changes and bio-psychosocial therapies. Dietary interventions vary depending on the type of AP-FGID. Bio-psychosocial therapies such as hypnotherapy, cognitive behavioral therapy and yoga aim at stress reduction.

CONCLUSION

There is increasing evidence for use of non-pharmacological interventions in children with APFGID.

Self-Perceived Food Intolerances Are Common and Associated with Clinical Severity in Childhood Irritable Bowel Syndrome

BACKGROUND

Adults with irritable bowel syndrome (IBS) frequently identify foods as exacerbating their gastrointestinal symptoms. In children with IBS, the prevalence of perceived food intolerances and their impact are unknown.

OBJECTIVE

Our aim was to determine the prevalence of self-perceived food intolerances and the relationship of these intolerances to abdominal pain, psychosocial distress, and quality of life in children with IBS.

DESIGN

We conducted a cross-sectional study. Questionnaire and prospective diary data were collected from 2008 to 2014 by trained research coordinators.

PARTICIPANTS/SETTING

Participants were children 7 to 18 years old (pediatric Rome III IBS, n=154; age-sex matched healthy children, n=32) in Houston, TX.

MEASURES

Perceived food intolerances and avoided foods were captured using the Childhood Food and Symptom Association Questionnaire. IBS severity was assessed by a ≥7-day pain diary and validated psychosocial questionnaires assessing quality of life, somatization, functional disability, depression, and anxiety.

STATISTICAL ANALYSES PERFORMED

We used descriptive Spearman bivariate correlation, χ(2), and Poisson log-linear generalized model with Wald χ(2) statistics.

RESULTS

A greater proportion of children with IBS (143 of 154 [92.9%]) vs healthy children (20 of 32 [62.5%]) identified at least one self-perceived food intolerance (χ(2)=22.5; P<0.001). Children with IBS identified a greater number (median=4 [25% to 75% quartile=2 to 6]) of perceived symptom-inducing foods than healthy children (median=2 [25% to 75% quartile=0 to 4]; χ(2)=28.6; P<0.001). Children with IBS avoided more foods (median=2 [25% to 75% quartile=1 to 4]) than healthy children (median=0 [25% to 75% quartile=0 to 2.75]; χ(2)=20.8; P<0.001). The number of self-perceived food intolerances was weakly associated (r value range= -0.17 to 0.21) with pain frequency, pain severity, somatization, anxiety, functional disability, and decreased quality of life.

CONCLUSIONS

Children with IBS have a high prevalence of self-perceived food intolerances. The number of these intolerances is weakly associated with measures of IBS severity.

Baroreflex mechanisms in Irritable Bowel Syndrome: Part I. Traditional indices

OBJECTIVE

This study was conducted to present evidence of differences in autonomic regulation of cardiovascular activity and its role in the severity of specific (disease-related) and non-specific (negative affect and chronic pain-related) symptoms in individuals with Irritable Bowel Syndrome (IBS).

METHODS

Seventy-eight female patients with IBS and 27 healthy women age 18-62 years were assessed for IBS symptoms, negative affect, and baroreceptor sensitivity (BRS), blood pressure (BP), heart rate, and heart rate variability (HRV) at rest. Direct and indirect regression effects were examined with application of the bootstrap procedure to validate findings.

RESULTS

IBS was reliably related to lower resting BRS, higher BP, and higher negative affect compared to healthy controls. Longer disease duration (chronicity) was related to BRS decrease coupled with systolic BP increase (95% CIs=-0.14 to -0.01). Three autonomic mechanisms associated with BRS decrease were found to further regulate severity of IBS symptoms. Lower BRS was related to higher IBS severity in general if the effect was transferred through the decrease of low frequency power of HRV (e.g., 95% CIs=-0.039 to -0.001 for abdominal pain severity). However, lower BRS was related to lower IBS severity in general if the effect was transferred through diastolic BP increase (95% CIs=0.01-0.11 for abdominal pain severity). Lower BRS was related to higher abdominal pain severity coupled with high negative affect if the effect was transferred through the decrease of higher frequency power of HRV (95% CIs=-0.026 to -0.003).

CONCLUSIONS

These findings indicate that different cardiovascular mechanisms are associated with IBS development and the increase and decrease of severity of IBS symptoms. Their assessment suggests ways to personalize treatment of IBS.

Treatment of Posttraumatic Abdominal Autonomic Neuropathy Manifesting as Functional Dyspepsia and Chronic Constipation: An Integrative East-West Approach

A 52-year-old male with a history of spinal cord injury and cauda equina syndrome resulting in neurogenic bladder presented with chronic constipation and functional dyspepsia that was refractory to medical management. He was treated with an integrative East-West approach including acupuncture, trigger point injections, and Tui Na massage. Both his pain and constipation improved after a series of treatments, and this improvement was largely sustained at 2-year follow-up. This patient's symptoms are consistent with damage to the visceral parasympathetic nervous system. Interestingly, many studies evaluating the mechanisms of acupuncture point to restoration of parasympathetic tone as a mechanism of action. In this article, we describe a case of complex functional gastrointestinal disorders associated with posttraumatic autonomic neuropathy that was refractory to pharmacotherapy and was successfully treated with an integrative East-West approach.

Effects of the Fourth Ventricle Compression in the Regulation of the Autonomic Nervous System: A Randomized Control Trial

Introduction. Dysfunction of the autonomic nervous system is an important factor in the development of chronic pain. Fourth ventricle compression (CV-4) has been shown to influence autonomic activity. Nevertheless, the physiological mechanisms behind these effects remain unclear. Objectives. This study is aimed at evaluating the effects of fourth ventricle compression on the autonomic nervous system. Methods. Forty healthy adults were randomly assigned to an intervention group, on whom CV-4 was performed, or to a control group, who received a placebo intervention (nontherapeutic touch on the occipital bone). In both groups, plasmatic catecholamine levels, blood pressure, and heart rate were measured before and immediately after the intervention. Results. No effects related to the intervention were found. Although a reduction of norepinephrine, systolic blood pressure, and heart rate was found after the intervention, it was not exclusive to the intervention group. In fact, only the control group showed an increment of dopamine levels after intervention. Conclusion. Fourth ventricle compression seems not to have any effect in plasmatic catecholamine levels, blood pressure, or heart rate. Further studies are needed to clarify the CV-4 physiologic mechanisms and clinical efficacy in autonomic regulation and pain treatment.

Characteristics of medically hospitalized pediatric patients with somatoform diagnoses

OBJECTIVES

To describe demographic, diagnostic, and psychosocial characteristics of medically admitted patients diagnosed with somatoform disorders.

METHODS

Retrospective chart reviews were performed for pediatric patients (ages 3-18 years) seen by the Psychiatry Consultation Service in 2010 and 2011 on inpatient medical/surgical units and diagnosed with somatoform disorders. Data included demographic information; patient medical history, physical symptom characteristics, and service utilization; psychiatric diagnoses, history, and comorbidities, patient temperament, and coping style; family characteristics; and academic and social characteristics.

RESULTS

Mean age for the 161 identified patients was 14.4 years. The majority of patients were female (75%) and white (73%). Chief physical symptoms were pain (58%) and neurologic symptoms (40%); 73% of patients had medical diagnoses, and 66% had a history of prior psychiatric treatment. The most common somatoform diagnoses, using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, were pain (50%) and conversion disorders (28%). Psychiatric comorbidities were predominantly mood and anxiety disorders (42% and 29%, respectively). Mean hospitalization length was 4.9 days, with 14% of patients readmitted with psychiatric reinvolvement during the study period. Patients had sensitive temperaments (80%) and internalizing coping styles (76%) and were described as "good children" (72%). School absences (55%), academic pressures (51%), and learning difficulties (36%) were reported.

CONCLUSIONS

Clarifying the prevalence and nature of such characteristics can help pediatric providers improve patient care and minimize unnecessary medical interventions with early detection of risk for somatoform processes, provision of psychoeducation for patients and families, and early referral to mental health clinicians.

Adolescent rumination syndrome

Rumination syndrome is the non-purposeful regurgitation of recently ingested food from the stomach to the mouth, where it is either expelled or reswallowed. Adolescent rumination syndrome (ARS) is a rare condition of which many physicians are unaware. Patients often are misdiagnosed or undergo costly testing, and as a result, diagnosis and treatment are often delayed. While ARS is not life-threatening, it does have medical and emotional effects on the patient and the patient's family. Diagnosis of ARS is based upon the Rome III diagnostic criteria. Antroduodenal manometry, while not required for a diagnosis, can be helpful to confirm the diagnosis. The pathogenesis of this disorder is complex and not well understood. However, because of its behavioral component, treatment of ARS requires a multidisciplinary approach that includes both medical management of symptoms and implementation of strategies that address behavioral, psychological, and general quality-of-life components of the disorder.

Relationship among nausea, anxiety, and orthostatic symptoms in pediatric patients with chronic unexplained nausea

This study evaluated the relationship among nausea, anxiety, and orthostatic symptoms in pediatric patients with chronic unexplained nausea. We enrolled 48 patients (36 females) aged 15 ± 2 years. Patients completed the Nausea Profile, State-Trait Anxiety Inventory for Children and underwent 70° head upright tilt testing (HUT) to assess for orthostatic intolerance (OI) and measure heart rate variability (HRV). We found nausea to be significantly associated with trait anxiety, including total nausea score (r = 0.71, p < 0.01) and 3 subscales: somatic (r = 0.64, p < 0.01), gastrointestinal (r = 0.48, p = 0.01), and emotional (r = 0.74, p < 0.01). Nausea was positively associated with state anxiety, total nausea (r = 0.55, p < 0.01), somatic (r = 0.48, p < .01), gastrointestinal (r = .30, p < .05), and emotional (r = .64, p < .01) subscales. Within 10 min of HUT, 27 patients tested normal and 21 demonstrated OI. After 45 min of HUT, only 13 patients (27%) remained normal. Nausea reported on the Nausea Profile before HUT was associated with OI measured at 10 min of tilt (nausea total r = 0.35, p < 0.05; nausea emotional subscale r = 0.40, p < 0.01) and lower HRV at 10 min of HUT (F = 6.39, p = 0.01). We conclude that nausea is associated with both anxiety symptoms and OI. The finding of decreased HRV suggests an underlying problem in autonomic nervous system function in children and adolescents with chronic unexplained nausea.

The use of non-narcotic pain medication in pediatric gastroenterology

The perception of pain in children is easily influenced by environmental factors and psychological comorbidities that are known to play an important role in its origin and response to therapy. Chronic abdominal pain is one of the most commonly treated conditions in modern pediatric gastroenterology and is the hallmark of 'functional' disorders that include irritable bowel syndrome, functional dyspepsia, and functional abdominal pain. The development of pharmacological therapies for these disorders in adults and children has been limited by the lack of understanding of the putative, pathophysiological mechanisms that underlie them. Peripheral and central pain-signaling mechanisms are known to be involved in chronic pain originating from the gastrointestinal tract, but few therapies have been developed to target specific pathways or enhance correction of the underlying pathophysiology. The responses to therapy have been variable, potentially reflecting the heterogeneity of the disorders for which they are used. Only a few small, randomized clinical trials have evaluated the benefit of pain medications for chronic abdominal pain in children and thus, the decision on the most appropriate treatment is often based on adult studies and empirical data. This review discusses the most common, non-narcotic pharmacological treatments for chronic abdominal pain in children and includes a thorough review of the literature to support or refute their use. Because of the dearth of pediatric studies, the focus is on pharmacological and alternative therapies where there is sufficient evidence of benefit in either adults or children with chronic abdominal pain.

Irritable bowel syndrome in children: pathogenesis, diagnosis and evidence-based treatment

Irritable bowel syndrome (IBS) is the commonest cause of recurrent abdominal pain (RAP) in children in both more developed and developing parts of the world. It is defined by the Rome III criteria for functional gastrointestinal disorders. It is characterized by abdominal pain that is improved by defecation and whose onset is associated with a change in stool form and or frequency and is not explained by structural or biochemical abnormalities. It is estimated that 10%-15% of older children and adolescents suffer from IBS. IBS can be considered to be a brain-gut disorder possibly due to complex interaction between environmental and hereditary factors. The diagnosis of IBS is made based on the Rome III criteria together with ruling out organic causes of RAP in children such as inflammatory bowel disease and celiac disease. Once the diagnosis of IBS is made, it is important to explain to the parents (and children) that there is no serious underlying disease. This reassurance may be effective treatment in a large number of cases. Lifestyle modifications, stress management, dietary interventions and probiotics may be beneficial in some cases. Although there is limited evidence for efficacy of pharmacological therapies such as antispasmodics and antidiarrheals; these have a role in severe cases. Biopsychosocial therapies have shown encouraging results in initial trials but are beset by limited availability. Further research is necessary to understand the pathophysiology and provide specific focused therapies.

Physiological underpinnings of irritable bowel syndrome: neurohormonal mechanisms

The gastrointestinal tract is a vast neuroendocrine organ with extensive extrinsic and intrinsic neural circuits that interact to control its function. Circulating and paracrine hormones (amine and peptide) provide further control of secretory, absorptive, barrier, motor and sensory mechanisms that are essential to the digestion and assimilation of nutrients, and the transport and excretion of waste products. Specialized elements of the mucosa (including enteroendocrine cells, enterocytes and immune cells) and the microbiome interact with other intraluminal contents derived from the diet, and with endogenous chemicals that alter the gut's functions. The totality of these control mechanisms is often summarized as the brain-gut axis. In irritable bowel syndrome (IBS), which is the most common gastrointestinal disorder, there may be disturbances at one or more of these diverse control mechanisms. Patients present with abdominal pain in association with altered bowel function. This review documents advances in understanding the pathophysiological mechanisms in the brain-gut axis in patients with IBS. It is anticipated that identification of one or more disordered functions in clinical practice will usher in a renaissance in the management of IBS, leading to effective therapy tailored to the needs of the individual patient.

Frequent abdominal pain in childhood and youth: a systematic review of psychophysiological characteristics

Background. Frequent abdominal pain (AP) in children and adolescents is often designated as functional gastrointestinal disorder. In contrast to research on psychological and social influences on the experience of AP in this population, psychophysiological features such as function of the autonomic nervous system, the central nervous system, or the endocrine system have rarely been studied. Methods. We conducted a systematic literature search for peer-reviewed journal articles referring to children with AP between 4 and 18 years. Studies on experimental baseline characteristics or reactivity of psychophysiological outcome parameters (autonomous nervous system, central nervous system, and endocrine parameters) were included. Key Results. Twelve of 18 included studies found psychophysiological differences between children with AP and healthy ones. These studies indicate a possible autonomic dysregulation and hypersensitivity of the central nervous system in children with AP following stimulation with stress or other intense stimuli. Mainly conflicting results were found regarding baseline comparisons of autonomic and endocrine parameters. Conclusions and Inferences. Frequent AP in children may be associated with an altered psychophysiological reaction on intense stimuli. It has to be considered that the current literature on psychophysiological characteristics of childhood AP is small and heterogeneous. In particular, multiparameter studies using validated experimental paradigms are lacking.

Functional somatic symptoms in childhood and adolescence

PURPOSE OF REVIEW

Functional somatic symptoms (FSS) are common in children and adolescents, but explanatory models that synthesize research findings are lacking. This article reviews the studies published from January 2012 to March 2013 that investigate the neurophysiological mechanisms that may underlie FSS.

RECENT FINDINGS

Studies from diverse medical disciplines suggest that FSS are associated with functional differences in hypothalamic-pituitary-adrenal function, imbalances in vagal-sympathetic tone, upregulation of immune-inflammatory function, and primed cognitive-emotional responses that serve to amplify reactivity to threatening stimuli, thereby contributing to the subjective experience of somatic symptoms.

SUMMARY

FSS appear to reflect dysregulations of the stress system. When seemingly disparate research findings are interpreted together within an overarching 'stress-system' framework, a coherent explanatory model begins to emerge.

Heart rate variability as a biomarker for autonomic nervous system response differences between children with chronic pain and healthy control children

Studies in adults have demonstrated a relationship between lowered heart rate variability (HRV) and poor health. However, less is known about the role of autonomic arousal in children’s well-being. The aim of the current study was to examine resting HRV in children with chronic pain compared to healthy control children and, further, to examine children’s HRV following a series of acute experimental pain tasks in both groups. Participants included 104 healthy control children and 48 children with chronic pain aged 8–17 years. The laboratory session involved a 5-minute baseline electrocardiogram followed by four pain induction tasks: evoked pressure, cold pressor, focal pressure, and a conditioned pain modulation task. After the tasks were complete, a 5-minute post-task electrocardiogram recording was taken. Spectral analysis was used to capture high-frequency normalized power and the ratio of low-to-high frequency band power, signifying cardiac vagal tone and sympathetic balance, respectively. Results revealed that children with chronic pain had significantly lower resting HRV (signified by low high-frequency normalized power and high ratio of low-to-high frequency band power) compared to healthy children; moreover, a significant interaction between groups and time revealed that children with chronic pain displayed a static HRV response to the pain session compared to healthy children, whose HRV was reduced concomitant with the pain session. These findings suggest that children with chronic pain may have a sustained stress response with minimal variability in response to new acute pain stressors.

Conditioned pain modulation in children and adolescents: effects of sex and age

Conditioned pain modulation (CPM) refers to the diminution of perceived pain intensity for a test stimulus following application of a conditioning stimulus to a remote area of the body, and is thought to reflect the descending inhibition of nociceptive signals. Studying CPM in children may inform interventions to enhance central pain inhibition within a developmental framework. We assessed CPM in 133 healthy children (mean age = 13 years; 52.6% girls) and tested the effects of sex and age. Participants were exposed to 4 trials of a pressure test stimulus before, during, and after the application of a cold water conditioning stimulus. CPM was documented by a reduction in pressure pain ratings during cold water administration. Older children (12-17 years) exhibited greater CPM than younger children (8-11 years). No sex differences in CPM were found. Lower heart rate variability at baseline and after pain induction was associated with less CPM, controlling for child age. The findings of greater CPM in the older age cohort suggest a developmental improvement in central pain inhibitory mechanisms. The results highlight the need to examine developmental and contributory factors in central pain inhibitory mechanisms in children to guide effective, age appropriate pain interventions.

PERSPECTIVE

In this healthy sample, younger children exhibited less CPM than did older adolescents, suggesting a developmental improvement in CPM. Cardiac vagal tone was associated with CPM across age. The current findings may inform the development of targeted, developmentally appropriate pain interventions for children.