Folinic acid-responsive seizures presenting as breakthrough seizures in a 3-month-old boy

Neonatal seizures associated with white-matter changes on neuroimaging suggest an etiology of hypoxic-ischemic encephalopathy. Metabolic and idiopathic etiologies are also considerations but are less likely. Despite the fact that two disorders associated with neonatal seizures are diagnosed by cerebrospinal fluid neurotransmitter analysis, such an analysis is not standard in the workup for idiopathic neonatal seizures. We describe an infant who had a prolonged delivery, seizures on the first day of life, and white-matter changes on neuroimaging. A progressive seizure disorder that was refractory to standard antiepilepsy medications developed at 2 months of age. Analysis of cerebrospinal fluid neurotransmitters at that time demonstrated a pattern consistent with folinic acid-responsive seizures. Seizures ceased 24 hours after starting folinic acid. Serial neuroimaging, electroencephalograms, and metabolic changes from this patient are presented. This case illustrates the importance of cerebrospinal fluid neurotransmitter analysis as part of the work-up for idiopathic neonatal seizures.