The Cyclic Vomiting Syndrome Threshold: A Framework for Understanding Pathogenesis and Predicting Successful Treatments

Landscape of Cyclic Vomiting Syndrome: From Bedside to Bench, Past to Present

Investigations into mechanisms of cyclic(al) vomiting syndrome (CVS) began at the bedside more than a century ago. The modern era started with the formation of the Cyclic Vomiting Syndrome Association in 1993 that helped initiate robust efforts in education, advocacy, family physician conferences, scientific symposia, dedicated clinical programs, therapeutic guidelines, and research. Even today, bedside clues continue to emerge with the recent description of cannabinoid hyperemesis syndrome (CHS) and subsequent evidence of a perturbed endocannabinoid system. The clinical picture of CVS has evolved from that of a straightforward emetic disorder related to migraine requiring short-term antiemetics or prophylactic anti-migraine therapy, to a complicated, heterogenous one with multiple comorbid associations (anxiety, dysautonomia) and endophenotypes (migraine, Sato, CHS). This expanded view has important therapeutic implications which necessitate managing the comorbidities which can in turn impact the disease itself and proffered promising evidence that behavioral management (meditation) and vagal neuromodulation appear efficacious with few untoward effects, perhaps by reestablishing autonomic (parasympathetic) balance. The pathophysiologic picture now appears to be inscribed on an autonomic polyvagal design but multiple additional pathways interact, some confirmed (NK1, CB1, HPA axis, PPM1D gene, biological calendar, estrogen), and others, possible (TRPV-1, CGRP, GDF-15, mitochondrial dysfunction, impaired cation transport). CVS and its cousin CHS continue to challenge clinicians and perplex investigators and in the current era require not only a critical mass of specific pathway expertise but also syncretic biopsychosocial thinking to integrate these disparate threads. We may have reached such a tipping point at this Symposium.

Acupuncture and electroacupuncture for cyclic vomiting syndrome with tachygastria in an adult: A case report

RATIONALE

Cyclic vomiting syndrome (CVS) is characterized by recurrent episodes of acute vomiting lasting <1 week, occurring independently and chronically. Management typically involves lifestyle interventions, supportive care, and preventative medication. In rare cases, CVS persists for decades in adults, requiring a multidisciplinary approach to improve symptoms and quality of life.

PATIENT CONCERNS

A 30-year-old male patient presented with a 7-year history of recurrent nausea and vomiting, which initially began in 2017. The episodes occurred without identifiable triggers such as alcohol or overeating, increasing in frequency from once every 4 months to 2 months. He expressed fear of severe deterioration, impacting his ability to eat freely, work, and enjoy his hobbies.

DIAGNOSES

He was diagnosed with CVS based on the Rome criteria. Cutaneous electrogastrography showed postprandial power decrease and tachygastria.

INTERVENTIONS

Regular acupuncture treatments, including electroacupuncture at ST36 with 3 Hz, were administered twice a week for 3 weeks, followed by weekly sessions for 5 additional weeks.

OUTCOMES

Over 11 treatment sessions across 8 weeks, no nausea or vomiting was observed. The visual analog scale (VAS) score for subjective gastrointestinal discomfort decreased from 67 to 0 after 4 weeks. The Nausea Severity Scale (NSS) score dropped from 14 to 0 after 4 weeks. The Functional Dyspepsia-related QoL score decreased from 16 to 0 after 8 weeks. The Nepean Dyspepsia Index-Korean version decreased from 80 to 8 after 8 weeks. Furthermore, the patient expressed high satisfaction with the treatment, and no adverse events were observed.

LESSONS

Acupuncture offers a significant and safe approach to relieving symptoms and enhancing the quality of life for patients with nausea and vomiting. Although this is a single case report, the findings suggest that acupuncture can improve treatment compliance and manage symptoms in adults with CVS. Further research, including clinical trials, is required to confirm these findings and understand the underlying mechanisms.

AGA Clinical Practice Update on Diagnosis and Management of Cyclic Vomiting Syndrome: Commentary

DESCRIPTION

The purpose of this American Gastroenterological Association (AGA) Institute Clinical Practice Update (CPU) is to review the available evidence and provide expert advice regarding the diagnosis and management of cyclic vomiting syndrome.

METHODS

This CPU was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. This expert commentary incorporates important as well as recently published studies in this field, and it reflects the experiences of the authors who are experts in treating patients with cyclic vomiting syndrome.

Cyclic vomiting syndrome: From pathophysiology to treatment

Cyclic vomiting syndrome (CVS) is a disorder characterized by recurrent and unpredictable episodes of intense vomiting, interspersed with periods of apparent wellbeing. This disorder, which primarily affects children and adolescents but can persist into adulthood, has recently been the subject of extensive study and analysis in the medical literature. The aim of the present review is to examine the most important aspects of the epidemiology, pathophysiology, subtypes, diagnostic criteria, and current management of CVS. Even though the exact etiology remains unknown, genetic factors (polymorphisms), nervous system alterations and autonomic dysregulation, and environmental factors (use and abuse of cannabinoids) are postulated as possible triggers. CVS has significant diagnostic challenges, given that there is no specific test for confirming its presence. Thorough evaluation of symptoms and the ruling out of other possible causes of recurrent vomiting are required. Management of CVS typically involves a multidisciplinary approach. Pharmacologic options are explored, such as antiemetics and preventive medications, as well as behavioral and psychologic support therapies. Treatment personalization is essential, adapting it to the individual needs of each patient. Despite advances in the understanding of CVS, it remains a significant clinical challenge. This disorder impacts the quality of life of those affected and their families, underscoring the ongoing need for research and the development of more effective treatment strategies.

Percutaneous electrical nerve field stimulation improves comorbidities in children with cyclic vomiting syndrome

Introduction

Children with cyclic vomiting syndrome (CVS) frequently suffer from disabling abdominal pain and comorbidities that impair quality of life. A noninvasive, auricular percutaneous electrical nerve field stimulation (PENFS) device is shown to be effective for abdominal pain in children with disorders of gut-brain interaction. We aimed to determine the effects of PENFS on pain, common comorbidities, and quality of life in pediatric CVS.

Methods

Children aged 8-18 years with drug-refractory CVS were enrolled in a prospective, open-label study receiving 6 consecutive weeks of PENFS. Subjects completed the following surveys at baseline, during/after therapy (week 6), and at extended follow-up approximately 4-6 months later: Abdominal Pain Index (API), State-Trait Anxiety Inventory for Children (STAI-C), Pittsburgh Sleep Quality Index (PSQI), and Patient Reported Outcome Measurement Information System (PROMIS) Pediatric Profile-37.

Results

Thirty subjects were included. Median (interquartile range, IQR) age was 10.5 (8.5-15.5) years; 60% were female. Median API scores decreased from baseline to week 6 (p = 0.003) and to extended follow-up (p < 0.0001). State anxiety scores decreased from baseline to week 6 (p < 0.0001) and to extended follow-up (p < 0.0001). There were short-term improvements in sleep at 6 weeks (p = 0.031) but not at extended follow-up (p = 0.22). Quality of life measures of physical function, anxiety, fatigue, and pain interference improved short-term, while there were long-term benefits for anxiety. No serious side effects were reported.

Conclusions

This is the first study to demonstrate the efficacy of auricular neurostimulation using PENFS for pain and several disabling comorbidities in pediatric CVS. PENFS improves anxiety, sleep, and several aspects of quality of life with long-term benefits for anxiety.Clinical trial registration: ClinicalTrials.gov, identifier NCT03434652.

Whole exome/genome sequencing in cyclic vomiting syndrome reveals multiple candidate genes, suggesting a model of elevated intracellular cations and mitochondrial dysfunction

Objective

To utilize whole exome or genome sequencing and the scientific literature for identifying candidate genes for cyclic vomiting syndrome (CVS), an idiopathic migraine variant with paroxysmal nausea and vomiting.

Methods

A retrospective chart review of 80 unrelated participants, ascertained by a quaternary care CVS specialist, was conducted. Genes associated with paroxysmal symptoms were identified querying the literature for genes associated with dominant cases of intermittent vomiting or both discomfort and disability; among which the raw genetic sequence was reviewed. "Qualifying" variants were defined as coding, rare, and conserved. Additionally, "Key Qualifying" variants were Pathogenic/Likely Pathogenic, or "Clinical" based upon the presence of a corresponding diagnosis. Candidate association to CVS was based on a point system.

Results

Thirty-five paroxysmal genes were identified per the literature review. Among these, 12 genes were scored as "Highly likely" (SCN4A, CACNA1A, CACNA1S, RYR2, TRAP1, MEFV) or "Likely" (SCN9A, TNFRSF1A, POLG, SCN10A, POGZ, TRPA1) CVS related. Nine additional genes (OTC, ATP1A3, ATP1A2, GFAP, SLC2A1, TUBB3, PPM1D, CHAMP1, HMBS) had sufficient evidence in the literature but not from our study participants. Candidate status for mitochondrial DNA was confirmed by the literature and our study data. Among the above-listed 22 CVS candidate genes, a Key Qualifying variant was identified in 31/80 (34%), and any Qualifying variant was present in 61/80 (76%) of participants. These findings were highly statistically significant (p < 0.0001, p = 0.004, respectively) compared to an alternative hypothesis/control group regarding brain neurotransmitter receptor genes. Additional, post-analyses, less-intensive review of all genes (exome) outside our paroxysmal genes identified 13 additional genes as "Possibly" CVS related.

Conclusion

All 22 CVS candidate genes are associated with either cation transport or energy metabolism (14 directly, 8 indirectly). Our findings suggest a cellular model in which aberrant ion gradients lead to mitochondrial dysfunction, or vice versa, in a pathogenic vicious cycle of cellular hyperexcitability. Among the non-paroxysmal genes identified, 5 are known causes of peripheral neuropathy. Our model is consistent with multiple current hypotheses of CVS.

Cyclic Vomiting Syndrome and Cannabis Hyperemesis Syndrome: The State of the Science

This article provides a narrative review of the state of the science for both cyclic vomiting syndrome and cannabis hyperemesis syndrome along with a discussion of the relationship between these 2 conditions. The scope of this review includes the historical context of these conditions as well as the prevalence, diagnostic criteria, pathogenesis, and treatment strategies for both conditions. A synopsis of the endocannabinoid system provides a basis for the hypothesis that a lack of cannabidiol in modern high-potency Δ 9 -tetrahydrocannabinol cannabis may be contributory to cannabis hyperemesis syndrome and possibly other cannabis use disorders. In concluding assessment, though the publications addressing both adult cyclic vomiting syndrome and cannabis hyperemesis syndrome are steadily increasing overall, the state of the science supporting the treatments, prognosis, etiology, and confounding factors (including cannabis use) is of moderate quality. Much of the literature portrays these conditions separately and as such sometimes fails to account for the confounding of adult cyclic vomiting syndrome with cannabis hyperemesis syndrome. The diagnostic and therapeutic approaches are, at present, based generally on case series publications and expert opinion, with a very limited number of randomized controlled trials and a complete absence of Level 1 evidence within the cyclic vomiting literature overall as well as for cannabis hyperemesis syndrome specifically.

Cardiac Vagal Regulation Is Impeded in Children With Cyclic Vomiting Syndrome

INTRODUCTION

The pathophysiology underlying cyclic vomiting syndrome (CVS) remains undefined. Scant data and distinct clinical features point to altered autonomic nervous system function. Autonomic signaling can be noninvasively assessed through cardiac indices of parasympathetic vagal regulation, which is reduced in children with disorders of gut-brain interaction. We aimed to examine dynamic cardiac vagal regulation in children with CVS compared with that in healthy controls (HC).

METHODS

A total of 31 children with CVS evaluated in a tertiary care CVS center and 66 HC (ages 8-18 years) underwent cardiac autonomic function assessment. Electrocardiogram recordings were conducted during 3-minute sit/stand/sit posture challenges. The electrocardiogram-derived variables heart period, respiratory sinus arrhythmia (RSA), and vagal efficiency (VE) were analyzed using linear regression and mixed-effects modeling.

RESULTS

After exclusion of medication confounders, 23 patients with CVS were included in analyses. Both groups were comparable in age, gender, and body mass index. Compared with HC, children with CVS had shorter heart period (standardized mean difference range: 1.15-1.22, all P values < 0.05) and lower RSA (SMD range: 0.66-0.88, all P values < 0.05). Patients with CVS had significantly lower VE during the entire course of posture shifts, compared with HC ( B = -19.87, SE = 6.95, t = -2.86, P = 0.005, SMD = 0.76).

DISCUSSION

Children with CVS have suboptimal parasympathetic autonomic regulation compared with HC, indexed by reduced RSA and VE, even during their interepisodic well phase. Abnormal vagal modulation may underlie CVS pathophysiology, comorbidities, and triggers. Assessing VE during posture stressors could inform therapeutic interventions.

Current understanding of the etiology of cyclic vomiting syndrome and therapeutic strategies in its management

INTRODUCTION

Cyclic vomiting syndrome is a chronic debilitating disorder of the gut-brain interaction and is characterized by recurrent episodes of nausea and vomiting.Recent studies indicate that it is common and affects 2% of the US population. Unfortunately, there is significant heterogeneity in the management of these patients in the medical community. This review article aims to bridge this gap and will review the epidemiology and etiology with a focus on management of CVS.

AREAS COVERED

This article reviews the epidemiology, and pathophysiology of CVS and impact on patients. It also discusses management based on recent guidelines based on which is intended for the busy clinician. A literature search was done using PubMed and key words "cyclic vomiting", "management", "etiology", and pathophysiology were used to identify articles of importance.

EXPERT OPINION

CVS is a complex, poorly understood disorder of gut-brain interaction (DGBI) and has a significant negative impact on patients, families and the healthcare system. Recent guidelines recommend a multidisciplinary approach to management using prophylactic therapy in moderate-severe CVS and abortive medication for acute flares. However more research is needed to better understand the pathophysiology and develop targeted therapies for CVS.

Health Care Resource Use and Associated Costs of Cyclic Vomiting Syndrome in the United States

BACKGROUND AND AIMS

This study aimed to estimate the extent of US health care resource use (HRU) and direct cost burden of cyclic vomiting syndrome (CVS).

Methods

We selected patients in the MarketScan Commercial and Medicare Supplemental databases with ≥1 inpatient (IP) or ≥2 outpatient (OP) claims for CVS between October 1, 2015 and June 30, 2019, and continuous insurance enrollment for ≥12 months before (baseline) and ≥3 months after first CVS diagnosis (index). Using propensity scores based on baseline characteristics, each patient with CVS was matched to ∼3 non-CVS controls. We annualized HRU and costs to accommodate varying follow-up periods. Multivariable regressions further balanced CVS and non-CVS groups, and differences in HRU and costs between the matched cohorts were compared to quantify the direct cost burden of CVS.

Results

Patients with CVS incurred significantly higher average annualized HRU, with the largest differences in emergency room (1.9 vs 0.4) visits and hospital IP (0.9 vs 0.1) stays (P < .001). Patients with CVS had significantly higher annual total health care costs ($57,140 vs $14,912), with IP spending as the primary driver ($28,522 vs $3250) of the cost difference (all P < .001). After multivariable regression adjustments, total health care costs remained 4.1 times higher for patients with CVS relative to non-CVS controls, with IP costs 12.3 times higher, emergency room costs 5.8 times higher, OP visit costs 2.9 times higher, and OP pharmacy costs 1.5 times higher (all P < .001).

Conclusion

Newly diagnosed patients with CVS have greater health care utilization and higher costs than matched non-CVS counterparts, suggesting substantial economic burden of CVS on the US health care system.

Chronic nausea and vomiting: a diagnostic approach

INTRODUCTION

Chronic nausea and vomiting (CNV) are commonly encountered symptoms in medical practice. CNV is the presenting symptom in a variety of gastrointestinal and non-gastrointestinal disorders. However, in a significant percentage of patients without an obvious underlying cause, CNV poses a significant diagnostic challenge to the evaluating physician.

AREAS COVERED

A comprehensive clinical history and physical examination form the foundation for further diagnostic work-up. In the present review, we discuss the diagnostic approach to CNV, highlighting the epidemiology, pathophysiology, causes, and modes of evaluation of this condition. Specific investigations, carefully guided by clinical assessment and tailored for each patient, would be more beneficial in diagnosing CNV than empirically performing a blanket of investigations.

EXPERT OPINION

Whilst CNV remains a historically challenging diagnostic and therapeutic dilemma, research into this topic is limited. Hence, there is a growing call for more research into diagnostic modalities for CNV. With scientific advancement and further research, it is hoped that easy-to-use, cheap, noninvasive novel diagnostic modalities for CNV will be available soon.

Greater intolerance to uncertainty predicts poorer quality of life in adults with cyclic vomiting syndrome

BACKGROUND

Cyclic vomiting syndrome (CVS) is an idiopathic disorder of gut-brain interaction characterized by recurrent bouts of nausea and vomiting. Although CVS negatively impacts quality of life (QOL), the determinants of impaired QOL among adult CVS sufferers are not fully understood. The unpredictability of CVS attacks may generate anticipatory anxiety and worsen quality of life in a substantial proportion of patients with CVS. Intolerance to uncertainty (IU) is a cognitive trait in which individuals experience distress when faced with unpredictable situations, particularly those with potentially negative consequences. Higher trait IU is a well-established vulnerability factor linked to the development of multiple psychiatric conditions, including anxiety. However, the extent to which higher IU is associated with impaired QOL in adults with CVS is not known.

METHODS

To explore this issue, we surveyed 118 adult CVS patients and obtained demographic information, clinical features, reported healthcare utilization, and standardized assessments of IU, anxiety and panic, and QOL.

KEY RESULTS

Adult CVS patients with higher IU did not report a greater frequency of CVS attacks or overall CVS-related healthcare utilization than those with lower IU. Yet, this group demonstrated substantially poorer physical and mental health-related QOL and higher rates of anxiety-spectrum disorders.

CONCLUSIONS & INFERENCES

Higher degrees of IU are associated with increased anxiety and reduced QOL in patients with CVS. IU is a malleable cognitive trait that can be targeted by cognitive behavioral therapy (CBT). Our results suggest that some CVS patients may benefit from non-pharmacologic therapies such as CBT.

Diagnoses of Exclusion in the Workup of Abdominal Complaints

Abdominal pain is a common complaint in the emergency department, comprising 8.8% of all visits. Despite advances in medicine and imaging, 20% to 30% of patients still leave the department without a definitive diagnosis, whichhis can be both distressing for patients and unsatisfying for providers. Diagnoses of exclusion can be perilous, and their application should be carefully considered in order to not overlook more emergent complaints. However, a working knowledge of diagnoses of exclusion can guide therapeutics and specialty referrals that can ultimately provide answers and relief to a patient population often at odds with available information and expectations.

The childhood migraine syndrome

Migraine is a complex genetic brain disorder with an intricate pathogenesis and polymorphous clinical presentations, particularly in children. In this Perspective, we describe the different phenotypes of migraine in children, including conditions that have been referred to in the International Classification of Headache Disorders as "syndromes that may be related to migraine''. Evidence is presented for the integration of abdominal migraine, cyclical vomiting syndrome, benign paroxysmal vertigo, benign paroxysmal torticollis and infantile colic into the unified diagnosis of 'childhood migraine syndrome' on the basis of clinical and epidemiological characteristics, and shared inheritance. In our opinion, such integration will guide clinicians from specialities other than neurology to consider migraine in the assessment of children with these disorders, as well as stimulate research into the genetics, pathophysiology and clinical features of all disorders within the syndrome. A diagnosis of childhood migraine syndrome would also enable patients to benefit from inclusion in clinical trials of old and new migraine treatments, thus potentially increasing the number of treatment options available.

Hot-Water Bathing Improves Symptoms in Patients with Cyclic Vomiting Syndrome and Is Modulated by Chronic Cannabis Use

BACKGROUND

Cyclic vomiting syndrome (CVS) is a chronic functional GI disorder; a characteristic compulsive "hot-water bathing" pattern is reported to alleviate symptoms during an acute episode. There is limited data on this bathing pattern: proposed mechanisms include core temperature increase via effects on cannabinoid type 1 receptors in the brain, skin transient receptor potential vanilloid 1 receptor stimulation, and blood flow shift from viscera to skin.

AIMS

We thus sought to characterize the hot-water bathing pattern in patients with CVS and identify differences between heavy cannabis users in comparison to occasional and non-users.

METHODS

We conducted a cross-sectional study of 111 patients with CVS at a single tertiary referral center. Questionnaires regarding clinical characteristics, hot-water bathing, and cannabis use were administered. Patients were classified based on cannabis usage into regular cannabis users (≥ 4 times/week), and occasional + non-users (< 4 times/week and no current use).

RESULTS

A total of 81 (73%) respondents reported the hot-water bathing behavior during an episode. The majority (> 80%) noted a marked improvement in nausea, vomiting, abdominal pain and symptoms associated with panic. Regular cannabis users were more likely to use "very-hot" water (50% vs. 16%, p = 0.01) and time to relief of symptoms was longer (> 10 min) in this group, compared to the rest of the cohort.

CONCLUSIONS

Hot-water bathing relieves both GI and symptoms related to panic in most patients which appear to be modulated by chronic cannabis use. These findings can help inform future physiologic studies in CVS pathogenesis.

Improvement of Cyclic Vomiting Syndrome with Outpatient Ketamine Infusions

Cyclic vomiting syndrome (CVS) is a disorder characterized by recurrent flares of nausea and vomiting, often with significant abdominal pain, of several days duration. Although traditional prophylactic and abortive treatments for CVS are often successful, a subset of CVS patients with chronic abdominal pain may not respond as well to standard therapies. This report is the first, to our knowledge, to describe the use of outpatient ketamine infusions as therapy for refractory CVS. We describe a 63-year-old woman with history of CVS who presented with abdominal pain and recurrent episodes of nausea and vomiting. She first received ketamine during an inpatient admission for a CVS flare, with the aim of treating the abdominal pain. Given her improvement, she was offered a series of outpatient ketamine infusions, which led to a significant reduction in her symptoms. Thus, ketamine may be useful as both an abortive and prophylactic therapy in CVS. Prior reports have noted the anti-emetic effects of ketamine in the perioperative setting, and there is emerging evidence for the use of ketamine infusions for the treatment of chronic pain. However, this report is the first to describe ketamine as a potential prophylactic treatment for CVS.

Cyclic vomiting syndrome: A narrative review and guide to management

OBJECTIVES/BACKGROUND

Cyclic vomiting syndrome (CVS) is a disabling disorder of gut-brain interaction manifested by stereotypical and severe episodes of nausea and vomiting. Prevalence data indicate that CVS affects 1-2% of children and there has been a recent dramatic rise in diagnosed adults.

METHODS

This narrative review summarizes relevant literature pertaining to pediatric and adult CVS and provides a guide to management based on extensive clinical experience.

RESULTS

More timely diagnosis is facilitated by an expert consensus diagnostic approach and limited testing. Some diagnostic tests of exclusion remain essential. These include an upper gastrointestinal (GI) contrast study to exclude intestinal malrotation and basic laboratory screening. An abdominal ultrasound is recommended to exclude renal hydronephrosis in children and biliary disease in adults. Exclusion of metabolic/genetic conditions is warranted in those with specific warning signs, presentation in infants/toddler age, and in those with refractory disease. In the absence of chronic GI symptoms, referral to a GI specialist for upper endoscopy is generally not necessary in children but recommended in adults. A large subset termed migraine-equivalent CVS display strong clinical and genetic features of migraine. A unifying pathophysiologic core concept involves neuronal hyperexcitability and aberrant central modulation of autonomic signals. This is coupled with multiple susceptibility factors including mitochondrial dysfunction/cellular energy deficits, a hyper-responsive hypothalamic-pituitary-adrenal axis and many comorbidities that increase vulnerability to triggering events. CVS episodes are frequently triggered by stressors and intercurrent illnesses. Lifestyle and non-pharmacological interventions thus play a pivotal role in successful management. Pharmacological therapies are categorized into abortive, supportive/rescue, and prophylactic treatments. The majority respond particularly well to migraine-focused treatment strategies.

CONCLUSION

Despite improved characterization and understanding, CVS remains classified as a functional disorder of brain-gut interaction that is often disjointly managed by generalists and subspecialists. Early recognition, evaluation, and management will facilitate care and improve outcomes. Further research into its natural history with common progression to migraine headaches, neuroendocrine mechanisms, and the pathophysiologic relation to migraine diathesis is much needed.

Cyclic Vomiting Syndrome in Children

Cyclic Vomiting Syndrome (CVS) is an underdiagnosed episodic syndrome characterized by frequent hospitalizations, multiple comorbidities, and poor quality of life. It is often misdiagnosed due to the unappreciated pattern of recurrence and lack of confirmatory testing. CVS mainly occurs in pre-school or early school-age, but infants and elderly onset have been also described. The etiopathogenesis is largely unknown, but it is likely to be multifactorial. Recent evidence suggests that aberrant brain-gut pathways, mitochondrial enzymopathies, gastrointestinal motility disorders, calcium channel abnormalities, and hyperactivity of the hypothalamic-pituitary-adrenal axis in response to a triggering environmental stimulus are involved. CVS is characterized by acute, stereotyped and recurrent episodes of intense nausea and incoercible vomiting with predictable periodicity and return to baseline health between episodes. A distinction with other differential diagnoses is a challenge for clinicians. Although extensive and invasive investigations should be avoided, baseline testing toward identifying organic causes is recommended in all children with CVS. The management of CVS requires an individually tailored therapy. Management of acute phase is mainly based on supportive and symptomatic care. Early intervention with abortive agents during the brief prodromal phase can be used to attempt to terminate the attack. During the interictal period, non-pharmacologic measures as lifestyle changes and the use of reassurance and anticipatory guidance seem to be effective as a preventive treatment. The indication for prophylactic pharmacotherapy depends on attack intensity and severity, the impairment of the QoL and if attack treatments are ineffective or cause side effects. When children remain refractory to acute or prophylactic treatment, or the episode differs from previous ones, the clinician should consider the possibility of an underlying disease and further mono- or combination therapy and psychotherapy can be guided by accompanying comorbidities and specific sub-phenotype. This review was developed by a joint task force of the Italian Society of Pediatric Gastroenterology Hepatology and Nutrition (SIGENP) and Italian Society of Pediatric Neurology (SINP) to identify relevant current issues and to propose future research directions on pediatric CVS.

Cyclic vomiting syndrome: an overview for clinicians

Introduction: Cyclic vomiting syndrome (CVS) is an under recognized entity causing significant impact on patient's lifestyle. CVS is characterized by recurrent episodes of abdominal pain, nausea, and vomiting leading to many emergency department presentations prior to diagnosis. Patients often have lengthy delays in starting appropriate therapy leading to significant physical and financial hardship. Most cases of cyclic vomiting syndrome are reversible by managing risk factors and starting on appropriate treatment.Areas covered: This review covers the diagnostic criteria, pathophysiology, risk factors, and treatment for CVS and provides a valuable resource for clinicians to review and help with managing this challenging syndrome. The latest literature regarding the diagnosis and management of CVS is summarized.Expert Opinion: The direction for future research in CVS and insights to managing CVS are summarized. The role of pain that can be frequently controlled by tricyclic antidepressants and lorazepam suggests a central nervous system (CNS) origin. A standardized treatment regimen for CVS must be implemented as patients do respond to current therapies but there is often a significant delay in initiation of treatment. Reviewed recent data looking at MRI brain changes in patients with CVS that may lead to a better understanding of the pathophysiology of this disease.

Cyclic vomiting syndrome: Pathophysiology, comorbidities, and future research directions

Cyclic vomiting syndrome (CVS) is characterized by severe episodic emesis in adults and children. Cannabinoid hyperemesis syndrome is an increasingly recognized CVS-like illness that has been associated with chronic cannabis use. There are significant gaps in our understanding of the pathophysiology, clinical features, comorbidities, and effective management options of CVS. Recommendations for treating CVS are based on limited clinical data, as no placebo-controlled, randomized trials have yet been conducted. Diseases associated with CVS, including migraine, mitochondrial disorders, autonomic dysfunction, and psychiatric comorbidities, provide clues about pathophysiologic mechanisms and suggest potential therapies. We review our current understanding of CVS and propose future research directions with the aim of developing effective therapy. Establishing a multicenter, standardized registry of CVS patients could drive research on multiple fronts including developing CVS-specific outcome measures to broaden our understanding of clinical profiles, to serve as treatment end points in clinical trials, and to provide a platform for patient recruitment for randomized clinical trials. Such a robust database would also facilitate conduct of research that aims to determine the underlying pathophysiological mechanisms and genetic basis for CVS, as well as identifying potential biomarkers for the disorder. Soliciting government and industry support is crucial to establishing the necessary infrastructure and achieving these goals. Patient advocacy groups such as the Cyclic Vomiting Syndrome Association (CVSA), which partner with clinicians and researchers to disseminate new information, to promote ongoing interactions between patients, their families, clinicians, investigators, to support ongoing CVS research and education, must be an integral part of this endeavor.

Addressing Medical Issues in Behavior Analytic Treatment

This article offers strategies to help behavior analysts address medical issues which may affect behavioral intervention, beginning with the intake process and continuing through treatment and the coordination of care with other healthcare providers. The Behavior Analyst Certification Board's ethical guidelines for seeking medical consultation are reviewed. The importance of documenting clients' medical histories at intake and keeping updated medical files is emphasized. Behavioral manifestations and data patterns that may serve as red flags for medical problems are reviewed, with an emphasis on clients with limited verbal skills who cannot describe their symptoms. Multiple aspects of the behavior analyst's role in the coordination of care for clients' medical conditions are discussed.

Chronic nausea and vomiting: evaluation and treatment

Nausea is an uneasy feeling in the stomach while vomiting refers to the forceful expulsion of gastric contents. Chronic nausea and vomiting represent a diverse array of disorders defined by 4 weeks or more of symptoms. Chronic nausea and vomiting result from a variety of pathophysiological processes, involving gastrointestinal and non-gastrointestinal causes. The prevalence of chronic nausea and vomiting is unclear, although the epidemiology of specific conditions, such as gastroparesis and cyclic vomiting syndrome, is better understood. The economic impact of chronic nausea and vomiting and effects on quality of life are substantial. The initial diagnostic evaluation involves distinguishing gastrointestinal causes of chronic nausea and vomiting (e.g., gastroparesis, cyclic vomiting syndrome) from non-gastrointestinal causes (e.g., medications, vestibular, and neurologic disorders). After excluding anatomic, mechanical and biochemical causes of chronic nausea and vomiting, gastrointestinal causes can be grouped into two broad categories based on the finding of delayed, or normal, gastric emptying. Non-gastrointestinal disorders can also cause chronic nausea and vomiting. As a validated treatment algorithm for chronic nausea and vomiting does not exist, treatment should be based on a thoughtful discussion of benefits, side effects, and costs. The objective of this monograph is to review the evaluation and treatment of patients with chronic nausea and vomiting, emphasizing common gastrointestinal causes.

Cyclic vomiting syndrome: diagnostic approach and current management strategies

Cyclic vomiting syndrome (CVS) is a disorder characterized by episodes of nausea and vomiting lasting for 1-5 days followed by asymptomatic periods. The etiology of CVS is unknown, but it shares similar characteristics to migraine headaches. CVS is generally classified as having four phases: prodromal, acute/vomiting/hyperemesis, recovery, and remission/interepisodic. Current management strategies include trigger avoidance, abortive and prophylactic medication therapies, and supportive care. The goal of therapy for the remission phase is prophylaxis of further episodes. Antidepressant, antiepileptic, and antimigraine medications show an overall reduction or remission of CVS symptoms in more than 70% of patients. This article provides a summary of diagnostic strategies and reviews current management strategies for CVS.

Managing cyclic vomiting syndrome in children: beyond the guidelines

Cyclic vomiting syndrome (CVS) in children is characterized by frequent hospitalizations, multiple comorbidities, and poor quality of life. In the absence of robust data, the treatment of CVS remains largely empiric starting with the 2008 NASPGHAN Consensus Statement recommendations of cyproheptadine for children < 5 years of age and amitriptyline for those ≥ 5 years with propranolol serving as the second-line agent. Comprehensive management begins with lifestyle alterations, and extends to medications, supplements, and stress reduction therapies. Standard drug therapy is organized by the four phases of the illness: (1) interictal (preventative medications and mitochondrial supplements), (2) prodromal (abortive agents), (3) vomiting (fluids/energy substrates, antiemetics, analgesics, and sedatives) and (4) recovery (supportive care and nutrition). Because the response to treatment is heterogeneous, clinicians often trial several different preventative strategies including NK1 antagonists, cautious titration of amitriptyline to higher doses, anticonvulsants, Ca²⁺-channel blockers, and other TCA antidepressants. When the child remains refractory to treatment, reconsideration of possible missed diagnoses and further mono- or combination therapy and psychotherapy can be guided by accompanying comorbidities (especially anxiety), specific subphenotype, and when available, genotype. For hospital intervention, IV fluids with 10% dextrose, antiemetics, and analgesics can lessen symptoms while effective sedation in some instances can truncate severe episodes.

CONCLUSION

Although management of CVS remains challenging to the clinician, approaches based upon recent literature and accumulated experience with subgroups of patients has led to improved treatment of the refractory and hospitalized patient. What is Known: • Cyclic vomiting syndrome is a complex disorder that remains challenging to manage. • Previous therapy has been guided by the NASPGHAN Consensus Statement of 2008. What is New: • New prophylactic approaches include NK1 antagonists and higher dosages of amitriptyline. • Strategies based upon comorbidities and subphenotype are helpful in refractory patients.

Emerging Topics in Gastroenterology

The bacteria and fungi in the human gut make up a community of microorganisms that lives in symbiosis with humans, engaging in numerous diverse interactions that influence health. This article outlines the current knowledge on emerging topics in gastroenterology, including microbiome and probiotics, fecal microbiota transplantation, cyclic vomiting syndrome, eosinophilic esophagitis, and microscopic colitis.