Citrullinemia type 1 manifesting with a stroke-like episode: a case report

Citrullinemia type 1 (CTLN1) is a rare inherited disorder caused by mutations in the argininosuccinate synthetase 1 (ASS1) gene, disrupting the urea cycle and leading to toxic ammonia accumulation. It typically presents in newborns with lethargy, vomiting, and poor feeding. Stroke-like neurological presentations are very rare. We report a 19-month-old boy presenting with sudden right-sided weakness, lethargy, and difficulty standing. Laboratory tests revealed elevated ammonia and plasma citrulline, while brain imaging showed extensive cortical and subcortical abnormalities with cerebral edema and midline shift. Genetic testing confirmed heterozygous mutations in the ASS1 gene, diagnosing CTLN1. Prompt treatment with intravenous sodium benzoate, arginine supplementation, and dietary protein restriction led to full neurological recovery over 10 months, with resolution of motor deficits and normalization of biochemical parameters. This case highlights the importance of considering metabolic disorders in acute stroke-like presentations and the value of early biochemical and genetic diagnosis for favorable outcomes.