Cyclic vomiting syndrome (CVS) is a disorder noted for its unique intensity of vomiting, repeated emergency department visits and hospitalizations, and reduced quality of life. It is often misdiagnosed due to the unappreciated pattern of recurrence and lack of confirmatory testing. Because no accepted approach to management has been established, the task force was charged to develop a report on diagnosis and treatment of CVS based upon a review of the medical literature and expert opinion. The key issues addressed were the diagnostic criteria, the appropriate evaluation, the prophylactic therapy, and the therapy of acute attacks. The recommended diagnostic approach is to avoid "shotgun" testing and instead to use a strategy of targeted testing that varies with the presence of 4 red flags: abdominal signs (eg, bilious vomiting, tenderness), triggering events (eg, fasting, high protein meal), abnormal neurological examination (eg, altered mental status, papilledema), and progressive worsening or a changing pattern of vomiting episodes. Therapeutic recommendations include lifestyle changes, prophylactic therapy (eg, cyproheptadine in children 5 years or younger and amitriptyline for those older than 5), and acute therapy (eg, 5-hydroxytryptamine receptor agonists, termed triptans herein, as abortive therapy, and 10% dextrose and ondansetron for those requiring intravenous hydration). This document represents the official recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition for the diagnosis and treatment of CVS in children and adolescents.

Cyclic vomiting syndrome (CVS) was initially described in children but can occur in all age groups. Cyclic vomiting syndrome is increasingly recognized in adults. However, the lack of awareness of CVS in adults has led to small numbers of diagnosed patients and a paucity of published data on the causes, diagnosis and management of CVS in adults. This article is a state-of-knowledge overview on CVS in adults and is intended to provide a framework for management and further investigations into CVS in adults.

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 hypothalamicpituitary-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 migrainefocused 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

We propose a mechanism in which RYR2 sequence variants result in aberrant stress-induced calcium release into the mitochondria of autonomic neurons, resulting in an increased risk to develop autonomic/functional disease such as CVS, and related conditions such as migraine and gut dysmotility. This model incorporates the existing hypotheses regarding CVS pathogenesis into a cohesive mechanism, and might have treatment implications.

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We appreciate your interest in our article 1 and agree that the two cases cited meet an acceptable diagnostic threshold for cannabinoid hyperemesis syndrome (CHS). These cases had long-term follow-up