Adult-onset seizures in a patient with Down syndrome and portosystemic shunt

Abstract

Objective: The prevalence of epilepsy in patients with Down syndrome (DS) is 5–13%, which is higher than the prevalence in the general population. Transient hyperammonemia is often observed following seizure, but it typically resolves within a day. Here, we describe the case a 37-year-old woman who had DS and a history of adult-onset epilepsy and was admitted to our hospital with recurrent seizures. After admission, her ammonia levels fluctuated without any apparent cause, and dynamic computed tomography revealed a portosystemic shunt. The findings suggest that her seizures possibly precipitated from hyperammonemia secondary to a portosystemic shunt, and we reviewed the relevant literature. Methods: We conducted PubMed, Web of Science, and EMBASE searches without language restrictions for articles published between 1970 and February 2013. Results: In addition to the present case, 7 cases were ultimately included in this review. Four patients were newborns, 2 patients were 1month old, and 1 patient was 3years old. No adult cases were described until now. Conclusion: Adult patients with DS diagnosed with epilepsy are not routinely assessed for portosystemic venous shunts. Measuring ammonia levels in patients with DS the day after admission would help detect portosystemic shunts, even if the patients have been previously diagnosed with epilepsy. Practice Implications: If ammonia levels fluctuate without any apparent cause after seizure, dynamic computed tomography should be performed, especially for patients with DS, whether or not they have been previously diagnosed with epilepsy.