One-third of children with cyclic vomiting syndrome, which is accompanied by severe headaches and/or nausea, appear to have a metabolic abnormality—mitochondrial dysfunction, fatty acid oxidation, or both.
WASHINGTON, DC—Certain metabolic abnormalities are common among pediatric patients with cyclic vomiting syndrome, researchers reported at the 53rd Annual Meeting of the American Headache Society. These abnormalities had previously not been implicated in the disease etiology.
“Cyclic vomiting syndrome is a chronic disorder of unknown etiology,” stated A. David Rothner, MD, Director of the Pediatric/Adolescent Headache Program at the Cleveland Clinic, and colleagues. “Our study aims were to examine the presentation, evaluation, and management of children with cyclic vomiting syndrome and determine whether they have any associated, previously undiagnosed, metabolic abnormalities.”
Characterizing Cyclic Vomiting Syndrome
To better understand the presentation, evaluation, and management of the disease, Dr. Rothner and colleagues collected information regarding anthropometrics, medical history, laboratory and radiologic studies, medications, and treatment outcomes for 100 patients (mean age, 8.9) at the time of diagnosis.
The disease is characterized by repeated stereotypical vomiting episodes accompanied by severe nausea and/or headache, with episodes typically occurring early in the morning, Dr. Rothner explained. In the study population, “patients reported cycles with a median duration of 24 hours, 18 vomiting episodes per cycle, and a peak of five vomits per hour at four-week intervals,” the researchers wrote.
“Twenty-six percent of patients had a personal history of migraine … 71% had a family history of migraine, and 10% had a family history of epilepsy,” Dr. Rothner said, noting that cyclic vomiting syndrome is considered one of the three primary migraine variants. Approximately two-thirds (66%) of the patients had some identifiable triggers, including viral illness and motion sickness. Autonomic symptoms, including fever and hypertension, were seen in 25%.
Metabolic Testing Results Were Difficult to Interpret
The investigators attempted to perform metabolic testing of blood and urine during both the well and ill phase of the disease in all patients. Of those patients who completed testing during one or both of the phases, 29% had results suggestive of mitochondrial dysfunction, and 2% had results suggestive of abnormal fatty acid oxidation, the researchers reported.
“Of the 16 patients who had testing at both phases, 13 had abnormalities, but three showed mitochondrial dysfunction when well and not when ill, four had abnormalities when ill but not when well, and another three had some combination of mitochondrial and fatty acid dysfunction during both times,” Dr. Rothner said. “When we looked at the metabolic testing based on timing, we expected to find more abnormalities at the time of acute illness, but this was not the case. The results were not consistent.”
Treatment Options Are Limited
Most patients (88%) reported complete symptom resolution between episodes, while 10% of episodes required IV fluids. “There is no agreed upon treatment for this disorder,” Dr. Rothner stated, but certain medications are beneficial in reducing symptoms. “For prophylactic treatment, amitriptyline was effective in 23 of 40 patients (58%), and cyproheptadine was effective in 30 of 61 (49%),” the investigators wrote. High-dose oral ondansetron also improved or resolved acute symptoms in 56 of 85 patients (66%).
“From the time cyclic vomiting syndrome begins until the time of diagnosis, there is often a two- or three-year delay, which is tragic,” Dr. Rothner concluded. “Increased understanding of cyclic vomiting syndrome will aid providers in making earlier diagnoses and instituting more effective treatment. Further results regarding evaluation and treatment outcomes are pending,” he said.
—Ariel Jones