Cyclic Vomiting Syndrome in an 18-Month-Old
For an 18-month-old with suspected cyclic vomiting syndrome, initiate cyproheptadine as first-line prophylactic therapy and educate caregivers to recognize prodromal symptoms for early abortive intervention with ondansetron. 1
Diagnostic Approach
Establish the diagnosis clinically using Rome IV criteria adapted for children: stereotypical episodes of acute-onset vomiting lasting <7 days, at least 3 discrete episodes in a year (with 2 in the prior 6 months), and episodes separated by at least 1 week of baseline health. 2, 1
Key Clinical Features to Identify
Prodromal symptoms occur in approximately 65% of patients and may include restlessness, anxiety, fatigue, abdominal pain, diaphoresis, or behavioral changes in young children who cannot verbalize an "impending sense of doom." 2
Stereotypical pattern is critical—each episode should follow the same temporal pattern, duration, and associated symptoms specific to this child. 2
Early morning onset is typical, with most episodes occurring in early morning hours. 2
Abdominal pain is present in most patients and should not exclude the diagnosis. 2
Essential Workup to Exclude Mimics
Rule out surgical emergencies first: Any bilious vomiting requires urgent fluoroscopy upper GI series to exclude malrotation or obstruction. 3
Basic laboratory evaluation: Complete blood count, serum electrolytes, glucose, liver function tests, and lipase to exclude metabolic or anatomic causes. 4
Consider Food Protein-Induced Enterocolitis Syndrome (FPIES) in this age group, which presents with acute repetitive vomiting 1-4 hours after suspect food ingestion without IgE-mediated allergic symptoms. 3
Screen for metabolic disorders if episodes are triggered by fasting or illness, though CVS remains a clinical diagnosis. 4
Treatment Strategy
Prophylactic Therapy (First-Line for This Age)
Cyproheptadine is the preferred prophylactic agent for young children, particularly those under 5 years of age. 1, 5
Start with age-appropriate dosing and titrate based on response over 2-4 weeks. 1
Use with caution in children with bronchial asthma or increased intraocular pressure. 1
Alternative prophylactic agents used in older children include amitriptyline (goal dose 1-1.5 mg/kg at bedtime), but this is typically reserved for older children and requires ECG monitoring for QTc prolongation. 4
Abortive Therapy During Episodes
Educate caregivers to recognize the prodromal phase (the critical window for intervention) and administer medications immediately at symptom onset, as early intervention dramatically increases the probability of aborting an episode. 2, 4
Ondansetron 8 mg sublingual (or age-appropriate dosing for an 18-month-old, typically 0.15 mg/kg) every 4-6 hours during the prodromal and emetic phases. 4
Sumatriptan is typically reserved for older children and adolescents, not routinely used in 18-month-olds. 4
Acute Episode Management (Emergency Department)
If the child presents during an active vomiting episode:
Aggressive IV fluid replacement with dextrose-containing fluids for rehydration and metabolic support. 4
Ondansetron 8 mg IV (or 0.15 mg/kg for pediatric dosing) every 4-6 hours as first-line antiemetic. 4
Place in a quiet, dark room to minimize sensory stimulation, as children in the emetic phase are often agitated. 4
IV ketorolac as first-line non-narcotic analgesia for severe abdominal pain (avoid opioids which worsen nausea). 4
Benzodiazepines for sedation in refractory cases to truncate the episode. 4
Trigger Identification and Lifestyle Modifications
Work with caregivers to identify and avoid triggers, which are present in 70-80% of CVS patients. 2
Common triggers in young children include infections, psychological stress (even positive events like birthdays), sleep deprivation, prolonged fasting, and travel. 2
Maintain regular sleep schedule and avoid prolonged fasting periods. 4
Stress management appropriate for the child's developmental stage. 4
Critical Pitfalls to Avoid
Do not miss bilious vomiting—this requires immediate surgical evaluation, not CVS management. 3
Do not overlook retching and nausea, which are equally disabling as vomiting itself and require aggressive treatment. 4
Do not misinterpret self-soothing behaviors (such as drinking large amounts of water) as malingering—this is specific to CVS. 2
Missing the prodromal window dramatically reduces abortive therapy effectiveness—caregiver education is paramount. 4
Prognosis and Follow-Up
Most children with CVS improve as they grow older, with 38% becoming symptom-free within years of diagnosis. 5
Evaluate response to prophylactic therapy after 2-4 weeks and adjust accordingly. 1
Monitor for reduction in episode frequency, duration, and emergency department visits as markers of treatment success. 5