What is Cyclic Vomiting Syndrome (CVS)?

Cyclic Vomiting Syndrome (CVS)

Cyclic vomiting syndrome (CVS) is a functional disorder characterized by stereotypical episodes of acute-onset, intense nausea and vomiting that last less than 7 days, occur at least 3 times per year with 2 episodes in the prior 6 months, are separated by symptom-free intervals of at least 1 week, and have no vomiting between episodes. 1, 2

Diagnostic Criteria and Clinical Features

CVS typically manifests in four distinct phases:

1. Prodromal Phase (occurs in ~65% of patients)

   • Lasts approximately 1 hour before vomiting onset
   • Symptoms include impending sense of doom, panic, and communication difficulties
   • Critical time for abortive therapy

2. Emetic/Vomiting Phase

   • Intense, uncontrollable vomiting
   • Episodes typically last <7 days
   • Often accompanied by abdominal pain

3. Recovery Phase

   • Gradual resolution of symptoms

4. Interepisodic/Remission Phase

   • Return to baseline health between episodes

Key Clinical Associations

• Migraine connection: 20-30% of CVS patients have comorbid migraine, suggesting shared pathophysiology 2
• Psychiatric comorbidities: 50-60% have mood disorders 2
• Autonomic dysfunction: Significant subgroup shows autonomic nervous system imbalance 2
• Hot water response: 48% of non-cannabis using CVS patients find relief from hot bathing 2

Differentiating CVS from CHS (Cannabinoid Hyperemesis Syndrome)

It's important to distinguish CVS from CHS:

• CHS: Prolonged (>1 year) and heavy cannabis use (>4 times weekly) precedes symptom onset 1
• CVS with cannabis use: Cannabis use is more occasional and often begins after symptom onset 1
• Diagnostic clarification: Cannabis cessation for 6 months or 3 typical cycle lengths is required to rule out CHS 1, 2

Management Approach

Acute Episode Management

1. Early intervention during prodromal phase (if possible):

   • Sumatriptan 20mg intranasal (can repeat after 2 hours if partial/no response) 2
   • Place patient in dark, quiet room 2

2. During active vomiting phase:

   • Aggressive IV hydration with dextrose-containing fluids (10% dextrose in normal saline)
     • Initial bolus: 10-20 mL/kg followed by maintenance fluids 2
   • Antiemetics:
     • Ondansetron 8mg every 6-8 hours 2
     • For refractory cases: haloperidol 0.5-2mg every 4-6 hours 2
   • Anxiety reduction: lorazepam 0.5-2mg every 4-6 hours 2
   • For severe refractory cases: aprepitant 125mg day 1, 80mg days 2-3 2

Prophylactic Management

For moderate-severe CVS (>4 episodes per year, each lasting >2 days with ED visits/hospitalizations):

1. First-line prophylaxis:

   • Tricyclic antidepressants (strongly recommended) 1, 2
     • Amitriptyline: Start at 25mg and titrate weekly to reach 75-100mg at bedtime 1, 2

2. Second-line options (if TCAs ineffective or not tolerated):

   • Topiramate
   • Aprepitant
   • Zonisamide
   • Levetiracetam 1, 2

Lifestyle Modifications

• Identify and avoid personal triggers
• Maintain regular sleep patterns
• Avoid prolonged fasting
• Implement stress management techniques 2
• Address comorbid conditions (anxiety, depression, migraines, sleep disorders) 1, 2

Common Pitfalls in CVS Management

1. Delayed diagnosis and treatment: Early intervention is critical for breaking the vomiting cycle 2

2. Repeated unnecessary testing: Avoid "shotgun" testing; use targeted testing based on specific red flags 2, 3

3. Misdiagnosis as CHS: Proper distinction requires detailed cannabis use history and cessation trial 1, 2

4. Inadequate hydration: Dehydration can perpetuate the vomiting cycle 2

5. Overlooking comorbidities: Addressing psychiatric and neurologic comorbidities is essential for effective management 2

6. Opioid overuse: Opioids should be avoided as they can worsen nausea and carry addiction risk 1

For patients with refractory symptoms, consider referral to specialists (neurologist, psychiatrist, or sleep specialist) and additional therapeutic approaches such as cognitive behavioral therapy 2.