Pyridoxal phosphat (vitamine B6) responsive West syndrome – follow up over 12 years

The West syndrome, known since 1841 is one of the most therapeutically resistant and unfavourable epilepsies of the first months of life. First line drug for treatment is vitamine B6. A response is really a 'lucky shot'. Long term follow up of neuropsychological outcome in these children is not available up to now. We report the course over 12 years on a boy with a vitamine B6 sensible West syndrome. He is the 2nd child of healthy parents, pregnancy and birth were normal. At the age of 6 months West syndrome of idiopathic origin started with typical seizures and hypsarrhythmia in the EEG. CSF GABA concentration before vitamine B6 (300mg/kg/body weight) was 8 pmol/ml (normal range 54–184 pmol/ml).

Treatment: From the 3rd day of vitamine B6 treatment the EEG was much better, from day 7 the child was seizure free with a normal EEG. At this point of therapy liquor GABA concentration was 96 pmol/ml. At intervals of 10 days vitamine B6 was reduced to 100mg/kg with sleep EEG before each reduction. 100mg/kg was given for 6 months. After 5 months on this dose a peripherel polyneuropathy developed with normalisation after cessation of vitamin B6. Brain MRT at the age of 18 months was normal, especially according to myelination. Without any therapy three uncomplicated febrile convulsions appeared between the age of 1 and 3 years. At the age of 6 years there was no neurologic deficit except a fine tremor. The neuropsychological investigation of the boy shows difficulties in memory skills, slight restriction of visual memory and dyslalia. Up to now at the age of 12 years the boy is seizure free. He visits the Hauptschule with good mental performance.

Summary: The vitamine B6 responsive West syndrome probably is associated with a good prognosis according to epilepsy and mental development. Our results of liquor GABA concentration before and during vitamine B6 therapy confirm the thesis of an age-dependent and temporary disturbance of the GABA metabolism. Therefore in our opinion this subgroup of West syndrome is a specific entity.