PYRIDOXINE-DEPENDENT SEIZURES - DEMOGRAPHIC, CLINICAL, MRI AND PSYCHOMETRIC FEATURES, AND EFFECT OF DOSE ON INTELLIGENCE QUOTIENT

A regional population-based survey identified six patients with pyrido xine dependency. Four presented on the first day of life and the other two at 1 and 8 months of age. Apart from multiple seizure types, othe r presenting features included jitteriness; encephalopathy, al first t hought to be hypoxic-ischaemic; hepatomegaly, and abdominal distension with bilious vomiting. Later problems included break-through fits wit h fever, transient visual agnosia; squint; severe articulatory apraxia ; motor delay with later dyspraxia; macrocephaly, and post-haemorrhagi c hydrocephalus. Magnetic resonance imaging showed variable structural abnormalities in all the early onset cases. Psychometric assessment r evealed a stereotyped pattern of intelligence scale subtest scores, wi th a specific impairment of expressive verbal ability. In a prospectiv e open study over one year, an increased dose of pyridoxine was associ ated with an improvement in IQ, particularly in performance subtests. Pyridoxine dependency is more common than has been thought. It has a w ider range of clinical features than the classical neonatal seizures a nd causes specific impairments of higher function, some of which may b e reversible. The dosage of pyridoxine should be optimal for IQ as wel l as seizure control.