Cyclical Vomiting Syndrome

A functional gastrointestinal disorder characterised by recurrent, discrete, stereotyped episodes of severe, often intractable vomiting. Between episodes there are symptom-free intervals with an entirely normal baseline of health. It occurs predominantly in children though is also recognised in adults.

It has a well established, close pathophysiological and clinical relationship to migraine. A substantial proportion of affected children go on to develop typical migraine headache in later life, and a family history of migraine is common.

It is an important diagnosis that is frequently underrecognised and substantially delayed. The dramatic, recurrent episodes can lead to extensive, repeated and frequently unrevealing investigation before the diagnosis is established.

Pathophysiology

• The precise pathophysiology remains incompletely understood.
• The close association with migraine, and some shared proposed mechanisms, have led to the condition being increasingly conceptualised as part of the broader migraine spectrum, particularly in children. The shared mechanisms include mitochondrial dysfunction, hypothalamic-pituitary-adrenal axis dysregulation, and autonomic nervous system dysfunction.
• An "abdominal migraine" variant is sometimes described. Cyclical vomiting syndrome and abdominal migraine are closely related and overlapping, but somewhat distinct clinical entities within this spectrum.
• Recognised triggers for individual episodes in a proportion of affected individuals include emotional stress or excitement. Both negative stress and positive excitement count, such as before a significant, anticipated event.
• Other triggers are specific foods (including chocolate and cheese, as in migraine), infection, and sleep deprivation.
• A substantial proportion of episodes occur without any clearly identifiable trigger.

• The defining clinical pattern is recurrent, discrete episodes of severe, intractable vomiting. They typically develop over a relatively short period (hours) and last from several hours to several days.
• The individual characteristically appears acutely, severely unwell during the episode, often pale, lethargic, and withdrawn.
• An essential diagnostic feature is return to an entirely normal, healthy baseline between episodes. Symptoms resolve completely, and growth, development, and general health are normal in the symptom-free intervals.
• This distinguishes the condition from persistent structural or metabolic pathology, which would be expected to produce more continuous or progressive symptoms.
• Associated features during an acute episode frequently include abdominal pain, pallor, and lethargy. In a proportion, headache and photophobia occur, reflecting the close relationship with migraine.
• In more severe or prolonged episodes, significant dehydration occurs and needs specific management.
• Episodes are frequently highly stereotyped for a given individual. Pattern, timing, duration, and associated features recur across successive episodes.
• This supports the diagnosis. Once it is established, the family and clinical team can anticipate and manage subsequent episodes based on the individual's own pattern.
• The dramatic, recurrent presentation frequently leads to substantial healthcare utilisation and repeated emergency department presentation. Before diagnosis, extensive investigation is directed at excluding a wide range of alternative causes.
• Prompt, confident diagnosis once the stereotyped pattern is recognised benefits the individual and family. It also avoids unnecessary, repeated, and generally unrevealing investigation.

• Diagnosis is clinical. It rests on the characteristic pattern of recurrent, discrete, stereotyped episodes with complete return to normal baseline health between episodes.
• Established diagnostic criteria are met. They generally require a minimum number of qualifying episodes, with specific criteria for episode duration and the symptom-free interval.
• A careful, detailed history characterising the pattern across multiple episodes is essential to confident diagnosis.
• Investigation is directed primarily at excluding alternative diagnoses, particularly in the initial assessment before the stereotyped pattern is clearly established.
• Consider and exclude metabolic and endocrine causes, given the episodic, recurrent presentation. These include an underlying inborn error of metabolism and adrenal insufficiency.
• Exclude structural gastrointestinal causes, including malrotation.
• Exclude an underlying central nervous system process, given some overlapping features. Neuroimaging is sometimes warranted, particularly with any atypical feature or evolving neurological sign, to exclude a structural cause including a posterior fossa lesion.
• Once the diagnosis is confidently established from a clearly characteristic, recurrent pattern, and alternatives have been appropriately excluded, further extensive investigation during similar episodes is generally not required.
• This avoids the burden of repeated, largely unrevealing investigation that frequently characterises the pre-diagnosis period.

• Acute episode management is supportive. Use a calm, quiet, darkened environment, reflecting the relationship with migraine and the frequent photophobia and sensory sensitivity.
• Ensure adequate hydration. Intravenous fluid support is required for more severe episodes with significant vomiting and dehydration risk.
• Give antiemetic treatment; ondansetron is a commonly used, generally effective option. Give analgesia for any associated significant abdominal pain or headache.
• Sumatriptan, a triptan with established efficacy in acute migraine, has shown benefit for acute episodes in some patients. It is a further acute option for appropriately selected patients, given the close relationship with migraine.
• Early intervention at the very onset of a recognised prodrome may abort or substantially reduce the severity of an evolving episode in some patients. It uses an antiemetic and, where appropriate, sumatriptan.
• This depends on family education about the individual's symptom pattern and early warning symptoms.
• Prophylactic treatment is considered for individuals with frequent, severe, or significantly disruptive episodes. Agents used in migraine prophylaxis are standard options, reflecting the shared prophylactic approach.
• Cyproheptadine is commonly used in younger children. Amitriptyline or propranolol is used in older children and adults.
• Identify and, where feasible, avoid recognised individual triggers, including attention to sleep, stress management, and specific dietary triggers.
• Educate the family on the generally benign, though highly disruptive, nature of the condition and its close relationship to migraine. Give clear guidance on the individual's management plan for acute episodes and, where used, prophylaxis.
• A substantial proportion of affected children experience gradual reduction in episode frequency over time. In many cases they eventually move to typical migraine headache as they enter adolescence and adulthood.