Cyclic Vomiting Syndrome in Children
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Direct answer
Cyclic vomiting syndrome (CVS) is a functional disorder of gut-brain interaction defined by Rome IV as two or more stereotypical episodes of intense, unremitting vomiting or retching lasting hours to days, occurring at least one week apart, with return to complete baseline health between episodes and no alternative explanation after appropriate evaluation. Episodes classically start at a predictable hour (often early morning or night), peak rapidly, and end as abruptly as they began; a migraine family history is frequent, and cannabis use should be probed in adolescents. Management divides into abortive therapy during attacks, supportive care with fluids and electrolytes, and prophylaxis (cyproheptadine in younger children, propranolol or amitriptyline in older ones) for frequent or severe episodes.
What you must remember
- Rome IV paediatric criteria: at least two stereotypical vomiting episodes hours to days long, a week or more apart, complete return to baseline health between episodes, symptoms not attributable to another disorder.
- The four phases: inter-episodic wellbeing, prodrome (nausea, pallor, knowing an attack is coming), emetic phase (vomiting up to many times per hour with lethargy), and recovery.
- Triggers to elicit: intercurrent infections, psychological excitement or stress (birthdays, examinations, school trips), motion sickness, prolonged fasting, cheese and chocolate, lack of sleep, and menses — avoiding triggers halves attack frequency in many children.
- Complications of severe attacks: dehydration, hypokalaemia and hyponatraemia, metabolic acidosis with ketosis, oesophagitis and, rarely, oesophageal tears; profound ketosis early in an attack is characteristic.
- Abortive therapy: early ondansetron plus a trial of sumatriptan (nasal or oral where age-appropriate) during the prodrome, with dark-quiet-room care; once vomiting is established, intravenous dextrose-containing fluids abort ketosis-driven worsening.
- Prophylaxis for frequent attacks: cyproheptadine in younger children; propranolol or amitriptyline in older children — the migraine-linked logic of CVS guides all three choices.
- Not everything cyclic is CVS: before labelling, exclude malrotation with volvulus, ureteropelvic junction obstruction, and metabolic disease (fatty-acid oxidation defects, mitochondrial cytopathy — the latter associated with maternal MELAS mutations); adolescent hot showers and chronic cannabis use suggest cannabinoid hyperemesis.
A typical attack walked through
Picture a seven-year-old who wakes at 4 a.m. with pallor and nausea, vomits every ten minutes by 6 a.m., and lies still, refusing water. Between episodes she is completely well; attacks arrive roughly every six weeks, twice after birthday parties. In the emergency department the sequence is: confirm the pattern from a diary (dates, trigger, duration), check ketones, electrolytes and glucose, and give intravenous 10 per cent dextrose with saline plus ondansetron — glucose matters because fasting and ketosis perpetuate the cycle. Resolution within hours to a day supports CVS; bile-stained vomit, abdominal distension or blood demands surgical review for malrotation. At follow-up, with four attacks in six months, prophylaxis starts (propranolol in this age group in many Indian centres), a trigger-avoidance plan is written for the school, and the family is taught to give ondansetron early in the prodrome. First-line investigation between attacks stays minimal — the diagnosis is clinical; abdominal ultrasound and, where suspicion exists, metabolic and mitochondrial testing are targeted, not reflexive.
Where students slip
Two traps recur. First, treating every recurrent vomiter as gastritis or "acidity": the stereotype — clock-like onset, explosive peak, complete wellness between attacks, migraine lineage — is diagnostic in a way no single test is, and proton pump inhibitors do nothing for CVS. Second, forgetting the mimics the exam loves: malrotation with intermittent volvulus (bile-stained vomiting, episodes not truly stereotypical), raised intracranial pressure (morning vomiting with headache and declining school performance, no wellness), and cannabinoid hyperemesis in adolescents (compulsive hot showers, relief by cessation). A subtle viva point: ketosis is not just a complication but an amplifier — early carbohydrate intake or intravenous dextrose breaks the metabolic loop, which is why management questions often hinge on dextrose-containing fluids rather than plain saline.
Frequently asked questions
What are the Rome IV criteria for cyclic vomiting syndrome in children?
At least two stereotypical episodes of intense vomiting or retching lasting hours to days, occurring at least one week apart, with complete return to baseline health between episodes and no better explanation.
Which drugs are first-line prophylaxis for frequent CVS attacks?
Cyproheptadine in younger children, with propranolol or amitriptyline in older children, chosen on the same principles as migraine prophylaxis.
Why are dextrose-containing fluids emphasised during an attack?
Fasting and ketosis drive the vomiting cycle; providing carbohydrate aborts ketosis and frequently shortens the emetic phase.
Which diagnosis must be excluded in a child with bile-stained episodic vomiting?
Malrotation with intermittent volvulus, which is surgical and can present with stereotyped episodes mimicking CVS.
What features suggest cannabinoid hyperemesis rather than CVS in an adolescent?
Chronic cannabis use, compulsive hot-water bathing for relief, and resolution only after cessation of cannabis.