Cyclic vomiting syndrome

CVS is a chronic disorder characterized by recurrent, regular, and stereotypical episodes of episodes of severe nausea and vomiting separated by symptom-free intervals.

The pathophysiology of CVS is complex and not fully understood, but it is believed to involve a dysregulation of the gut-brain interaction. Functional brain imaging studies have shown altered connectivity in the insular cortex in patients with CVS. Psychosocial and neurohormonal factors are also involved in the pathogenesis of CVS. Gastric emptying is accelerated in most patients with CVS, while others have normal gastric emptying. In a minority, gastric emptying may be intermittently delayed. There is an overlap between CVS, functional dyspepsia, and IBS.

The prevalence of CVS in the US is estimated at 2%. The incidence and prevalence of CVS decrease with age, with a prevalence in children reaching up to 6.2%.

Risk factors include a family history of the condition, psychological stress, and a personal or family history of migraines (40-70%). CVS shares many features with migraines, including auras and photophobia, and is often considered a variant of migraines. Some studies have also found an association between CVS and chronic cannabis use.

Clinically, CVS presents as stereotypical episodes of severe vomiting lasting from a few hours to several days, separated by symptom-free intervals, occurring two or fewer times per month. These episodes often begin at the same time of day, usually early in the morning. A CVS episode typically has four phases: prodromal, vomiting, recovery, and inter-episodic (asymptomatic). During the prodromal phase, patients often experience nausea, sweating, irritability, abdominal pain, fatigue, temperature changes, or insomnia. The vomiting phase is characterized by intense, often bilious vomiting, accompanied by disabling nausea, retching, and severe abdominal pain. Additional symptoms may include pallor, lethargy, listlessness, anorexia, headache, photophobia, low-grade fever, or hypothermia. Symptoms resolve during the recovery phase. In the inter-episodic phase, no vomiting occurs, and patients may be completely asymptomatic regarding the gastrointestinal system or have milder gastrointestinal symptoms. Symptoms can be triggered by psychological or physical stress. Cannabinoid hyperemesis syndrome is a CVS induced by high-dose and prolonged cannabis use, characterized by severe, cyclic episodes (≥ 3 per year) of nausea and vomiting with ab acute onset and a duration of less than a week.

The prognosis of CVS varies. While the syndrome can persist into adulthood, symptoms may lessen over time. The disease burden can be significant, impacting the QoL and resulting in frequent hospitalizations.