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Mafalda Rebelo1, Carla Conceição2, José Pedro Vieira3, Ana Ferreira4

1Pediatrics Department, Hospital Dona Estefânia , CHLC, EPE, Lisbon, Portugal.
2Imagiology Department, Hospital Dona Estefânia , CHLC, EPE, Lisbon, Portugal.
3Pediatric Neurology Service, Hospital Dona Estefânia , CHLC, EPE, Lisbon, Portugal.
4Metabolic Diseases Unit, Hospital Dona Estefânia , CHLC, EPE, Lisbon, Portugal.

- 13º Simposium Anual da Sociedade Portuguesa de Doenças Metabólicas, Évora, 16 a 18 de março de 2017 (poster em sala)

Background: Ischemic stroke in children has an annual incidence of 0.6 to 7.9/100,000 children and is most commonly attributed to cardiac, vascular, hematologic or infectious aetiology. Inherited metabolic disorders, some of them treatable, represent an uncommon cause of stroke-like events. Ornithine transcarbamylase deficiency (OTCD) is a X-linked inborn error of metabolism of the urea cycle that can manifests at any age with episodes of hyperammonemia causing encephalopathy, and rarely metabolic stroke.
Case Presentation: A 18-month-old female presented to the emergency department with lethargy after a fall from a chair. She had a history of daily vomiting for up to 3 months and more recently somnolence and ataxia, with frequent falls. She had adequate growth and no selective refusal to food. Head CT scan revealed bilateral cortico-subcortical fronto-temporo-parietal hypodense areas, more extensive on the right, suggesting subacute stroke. Subsequent MRI showed that these lesions had diffusion restriction only in the cortex and not in the white matter with normal MR angiography, more suggestive of a non-vascular insult, namely of metabolic origin. Furthermore, there was no evidence of vascular, haematologic or infectious aetiology on complementary exams. Due to rapid neurological deterioration with left brachial hemiparesis and reduced level of consciousness, lactate and ammonia level were checked and ammonia was found to be elevated (276 μmol/L), raising the suspicion of a urea cycle disorder (UCD). Immediate treatment with high glucose and lipid infusion, ammonia scavengers and cessation of dietary protein lead to with rapid normalization of ammonia levels and progressive resolution of symptoms. Plasma amino acids and urinary organic acids showed high glutamine (1258.9uM), low citrulline (0.7uM) and increased orotic acid (263.7μmol/mmol creatinine), suggesting the diagnosis of OTCD. During recovery she had a partial seizure controlled with anti-epileptic therapy. During the 4,5 months follow up she has been growing normally, with slight psychomotor delay, no further episodes of ataxia, hemiparesia or vomiting, Molecular genetic testing is awaited.
Comments: Our aim is to underline that urea cycle disorders should be thought in a patient with stroke-like episode especially if preceded of recurrent vomiting and ataxia. Prompt diagnosis and treatment is essential as duration and severity of hyperammonemia strongly correlates with brain damage.