Neonatal epileptic encephalopathy

Neonatal epileptic encephalopathy (NEE) often presents within hours of birth with intractable seizures. Progressive deterioration can lead to death within weeks. Brautigam et al reported twins with fatal NEE and biochemistry suggestive of reduced activity of AADC (figure).1,2 We are aware of two similar cases in the UK which were also fatal (M Champion, personal communication). In some patients with NNE, a response to pyridoxine treatment suggests a metabolic basis for NEE but the exact defect has not been confirmed (pyridoxine dependency, OMIM 266100). A report from Taiwan described an infant whose seizures were controlled by pyridoxal-P but not by pyridoxine, suggesting defective conversion of pyridoxine to pyridoxal-P.3 This case report demonstrates that NEE with biochemical findings mimicking AADC deficiency is the same disorder as the syndrome of pyridoxine-resistant pyridoxal-P-sensitive seizures. Biochemical investigation of NEE can reveal a potentially fatal disorder that responds dramatically to pyridoxal-P. Defective conversion of pyridoxine to pyridoxal-P is probably due to deficiency of pyridox(am)ine phosphate oxygenase.4 In a neonate who has had fetal distress and acidosis, there is a danger of attributing seizures to hypoxic-ischaemic encephalopathy, when there may be a rare but treatable metabolic disease.