Status epilepticus in a neonate treated with pyridoxine because of a familial recurrence risk for antiquitin deficiency: pyridoxine toxicity?

Pyridoxine‐dependent epilepsy (PDE) is a treatable inborn error of metabolism with autosomal recessive inheritance. Antenatal and postnatal prophylactic administration of pyridoxine has been recommended to improve the developmental outcome in possible future pregnancies. We report on a male offspring of a second pregnancy at risk for PDE. While on prophylactic treatment with oral pyridoxine, the newborn developed encephalopathy and status epilepticus at age 14 days. Seizures did not respond to parenteral pyridoxine and additional treatment with folinic acid. After treatment was changed to pyridoxal 5′‐phosphate, the infant’s condition improved. Antiquitin deficiency was excluded by biochemical and molecular genetic testing, and cofactor treatment was stopped on day 26. He has since remained seizure‐free with normal psychomotor development. In healthy newborns, high‐dose treatment with pyridoxine may result in increased rather than decreased neuroexcitability. Postnatal prophylactic pyridoxine treatment of fetuses and neonates at risk for PDE should be limited to the shortest possible time, by either prenatal diagnosis or immediate postnatal biochemical and genetic testing.