Abstracts

Pyridoxine-responsive seizures are classically neonatal in onset, due to pyridoxine deficiency or dependency. They are attributed to GAD deficency in GABA synthesis, but no gene defect has been identified. In a consecutive series of over 5,000 children with epilepsy studied over 25 years, 3 cases of pyridoxine-responsiveness are identified by IV pyridoxine 5-15 mg/kg during EEG recording: Case1. Newborn with seizures in week 1 of life, responding to pyridoxine 50 mg/day;
Case 2. Infant with seizures at 11 months, controlled on pyridoxine 100mg/dzy, with EEG normalization, off phenobarbitol by 4 years of age, with low pyridoxine but high serum alkaline phaophatase levels;
Case 3. Adolescent with seizures refractory to AEDs from 12 , responding to pyridoxine 200mg/day, even after discontinuation of all AEDs over 6 years.
Cases 1 and 2 were developmentally delayed but case 3 was normal at 18 years of age. All followup EEGs were normalized after their seizures responded to monotherapy pyridoxine. In addition to neonatal seizures, and reported infantile spasms from Japan, the phenotypic presentation for pyridoxine-resposive seizures should include epileptic encephalopathy of infancy and childhood, and even adolescents with seizures refractory to standard AEDs. A high index of suspicion must be confirnmed by pyridoxine challenge during a therapeutic EEG test.