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 vomiting lasting less than 7 days, with at least 3 discrete episodes per year separated by symptom-free periods of at least 1 week. 1, 2

Diagnostic Criteria

According to the Rome IV criteria, CVS diagnosis requires:

• Stereotypical episodes of acute-onset vomiting lasting <7 days
• At least 3 discrete episodes in a year, with 2 occurring in the prior 6 months
• Episodes separated by at least 1 week of baseline health
• Absence of vomiting between episodes (though milder symptoms like nausea, occasional vomiting, and dyspepsia may be present) 1, 2

A personal or family history of migraine headaches is considered a supportive criterion for CVS diagnosis.

Clinical Phases of CVS

CVS typically progresses through four distinct phases:

1. Prodromal Phase:

   • Occurs in approximately 65% of patients
   • Lasts a median of 1 hour before vomiting onset
   • May include impending sense of doom, panic, and communication difficulties
   • Ideal time for abortive therapy intervention 1

2. Emetic/Vomiting Phase:

   • Characterized by uncontrollable retching and vomiting lasting hours to days
   • Patients may drink large amounts of water or induce vomiting for temporary relief
   • Hot water bathing/showering is common (48% of non-cannabis using patients) 1, 2

3. Recovery Phase:

   • Gradual resolution of symptoms
   • Return to baseline function

4. Interepisodic/Remission Phase:

   • Symptom-free periods between episodes 3

Associated Symptoms and Comorbidities

During CVS episodes, patients may experience:

• Constitutional symptoms: fatigue, feeling hot/cold
• Cognitive/affective symptoms: mental fog, anxiety, restlessness
• Autonomic symptoms: diaphoresis, flushing
• Motor symptoms: shakiness, tremulousness
• Abdominal pain (present in most patients)
• Early morning onset is common 1

Common comorbidities include:

• Mood disorders (anxiety, depression, panic disorder): 50-60% of patients
• Migraine: 20-30% of patients
• Seizure disorders: approximately 3% of patients
• Autonomic imbalances including postural orthostatic tachycardia syndrome 1

Severity Classification

CVS can be classified as:

• Mild CVS: <4 episodes/year each lasting <2 days, without ED visits or hospitalizations
• Moderate-Severe CVS: ≥4 episodes/year, each lasting >2 days, requiring ED visits or hospitalizations 1, 2

Common Triggers

Triggers are identified in 70-80% of patients and include:

• Stress (both negative and positive events)
• Sleep deprivation
• Hormonal fluctuations (menstrual cycle)
• Travel and motion sickness
• Physiological stressors (infections, surgery)
• Prolonged fasting
• Intense exercise 1, 2

Pathophysiology

While the exact etiology remains unknown, several factors are implicated:

• Genetic factors (polymorphisms)
• Nervous system alterations and autonomic dysregulation
• Environmental factors (including cannabis use in some cases)
• Shared pathophysiological mechanisms with migraine 4

Clinical Course

CVS can begin in childhood or adulthood, with age of onset ranging from 2 to 49 years. The disorder can persist for decades, with some patients experiencing a worsening trajectory characterized by increased episode length and frequency. Coalescence of episodes over time indicates deterioration in the course of CVS. However, the prognosis is favorable in the majority of patients 1, 5.

Diagnostic Pitfalls

Common pitfalls in CVS diagnosis include:

• Misinterpreting self-induced vomiting as malingering rather than a self-soothing behavior
• Attributing hot water bathing exclusively to cannabinoid hyperemesis syndrome (CHS) when it occurs in 48% of non-cannabis using CVS patients
• Failing to recognize abdominal pain as a common feature of CVS
• Delayed or missed diagnosis due to lack of awareness about CVS in adults 1, 5

Understanding the characteristic patterns, phases, and associated features of CVS is essential for accurate diagnosis and effective management of this challenging but treatable disorder.