Vomissements associés à une stagnation pondérale et convulsions: penser à une anomalie du cycle d’urée

In some inherited metabolic diseases, in particular in urea cycle disorders, which are usually diagnosed in neonatal period or in childhood, vomiting is often the first symptom. We report a case of late revelation of urea cycle disorder in a 13 years old female patient hospitalized for convulsions and failure to thrive. The patient underwent an interview revealing chronic vomiting associated with behavioral disorders, ideomotor slowdown and headaches. Clinical examination showed ataxia. Lumbar puncture and head CT scan were normal. The patient had substantially elevated blood ammonia level at 75 micromoles/L (11-50). Chromatography of amino acids in the blood showed increased glutamine and alanine. Chromatography of amino acids in the urine showed increased basic amino acids evoking a deficit of the urea cycle due to deficit of the enzyme argininosuccinate lyase. The patient was treated as an emergency, exclusively with glycolipid-diet and sodium benzoate, allowing improvement of patient’s clinical condition and weight resumption. The seizures were controlled by phenobarbital. Family interview revealed that patient’s sister, aged 20 years, had a 3-year history of seizures treated with phenobarbital. She underwent metabolic assessment in our department, which showed the same urea cycle abnormality as hes sister. Urea cycle deficiency should be suspected in patients of any age with encephalopathy associated with epilepsy, vomiting, weight stagnation and hyperammonemia. The diagnosis is very often made during severe neurodigestive attack involving vomiting, attack and/or seizures.