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Cyclical vomiting syndrome is a disorder of unknown aetiology, characterised by recurrent stereotypic episodes of nausea and vomiting, with full recovery between attacks.1 The onset may be within the first three years of life,2 although UK studies have found the average age of onset to be 5.3 years.3 Childhood co-morbidities include motion sickness, constipation, and abdominal migraine.4 Exacerbations can be triggered by physical factors (infection, tiredness, pain, exercise, foods) and psychological stresses, both positive and negative. The attacks usually subside in adolescence, at which stage many develop migraine headaches.4
Our 7 year old patient first presented with vomiting and constipation at 2 years of age. Over time, he suffered repeated stereotypical episodes. Extensive blood investigations and radiological studies were negative. He was diagnosed with cyclical vomiting syndrome. Attempts to control the frequent attacks were made with anti-emetics, prokinetics, antacids, proton pump inhibitors, tricyclic antidepressants, β blockers, 5-HT1 antagonists, and antihistamines. None were effective, although sedation with lorazepam during exacerbations reduced the length of hospitalisation. Since diagnosis, he had been an inpatient on 48 occasions. Notably, recent hospital admissions were of increasing frequency, with incomplete recovery between attacks. At age 6 years, he was empirically started on L-carnitine at 50 mg/kg daily. Pre- and post-treatment carnitine levels were within normal range. Eighteen months later, he has been an inpatient only once with a vomiting episode.
L-carnitine is a naturally synthesised amino acid derivative. It is a co-factor in transporting fatty acids across the mitochondrial cell membrane. Dietary supplementation is indicated in primary carnitine deficiency disorders, haemodialysis patients, and in inherited metabolic conditions with secondary carnitine deficiency such as organic acidaemias and fatty acid oxidation defects.5 The success of L-carnitine prophylaxis in reducing the frequency of attacks in cyclical vomiting was first reported in 2002 by Calcar et al in a series of six patients.6
The trial of carnitine proved to be extremely effective in the management of this child’s condition. Although his blood levels were normal, carnitine dependence may be an important metabolic requirement in cyclical vomiting syndrome patients because of a high metabolic turnover. As far as we are aware, this is the most striking improvement by L-carnitine ever reported in the literature. L-carnitine responsive cyclical vomiting syndrome is a possible subgroup or phenotype in the diagnostic workup of children with this syndrome, and should be considered an early treatment option in children suffering from intractable cyclic vomiting.