Status epilepticus in a newborn – pyridoxine toxicity?

Aims: Pyridoxine dependent epilepsy (PDE) (MIM 266100) is a treatable neonatal encephalopathy with autosomal recessive inheritance. In view of possible positive effects on developmental outcome, antenatal and postnatal prophylactic treatment of siblings at risk has been recommended. Until now, no side effects of prophylactic treatment have been reported.

Case report: We report on a male sibling of a child with PDE who following antenatal (100–200mg per day) and postnatal (30mg per kg bodyweight and day) prophylactic treatment with pyridoxine developed encephalopathy and status epilepticus at age 14 days accompanied by großly elevated creatin kinase. His seizures did not respond to parenteral pyridoxine and additional treatment with folinic acid. After treatment was changed to pyridoxal phosphate (30mg per kg bodyweight and day), his condition improved. Following exclusion of PDE by biochemical and molecular genetic testing on day 26, cofactor treatment was stopped. He has since remained seizure free with normal development.

Conclusion: In healthy newborns, high dose treatment with pyridoxine may result in increased rather than decreased neuroexcitability. Prophylactic pyridoxine treatment of at risk fetuses and neonates should be limited to the shortest possible time by either prenatal diagnosis or postnatal biochemical (plasma pipecolic acid and urinary L-α-aminoadipic-semialdehyde) and genetic testing (antiquitin gene).