Longitudinal MRI findings in pyridoxine-dependent seizures.
BACKGROUND
Pyridoxine dependency is an uncommon familial cause of intractable seizures in newborns and infants. Fewer than 100 patients have been reported, and only four reports have included examples of brain imaging findings. We report the first longitudinal MRI findings in two patients with this condition.


METHODS
Six brain MR scans, three each from two patients with pyridoxine-dependent seizures, were reviewed. Morphometry of selected axial images was performed to calculate the ventricle-to-brain ratio (VBR).


METHODS
A girl, followed for 5 years, presented with intrauterine fetal seizures and neonatal seizures, and pyridoxine dependency was confirmed at 3.5 months of age. This patient had a subsequent history of poor compliance with pyridoxine therapy and severe developmental disability. A boy, followed for 9 years, presented with neonatal seizures, and pyridoxine dependency was diagnosed at 8 months of age.


RESULTS
The serial MR scans demonstrated progressive dilation of the ventricular system and atrophy of the cortex and subcortical white matter together with an increase in the VBR. These progressive abnormalities were greater in the 5-year-old girl.


CONCLUSIONS
Pyridoxine-dependent seizures are due to an inborn abnormality in the pyridoxine-dependent synthesis of gamma-aminobutyric acid (GABA). The progressive MR changes may be due to chronic excitotoxicity caused by an imbalance of cerebral levels of GABA and glutamic acid.
Department of Neurology, University of California, Davis, USA.
S M
SM
Gospe
S T
ST
Hecht
D001284:Atrophy; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004827:Epilepsy / Q000175:diagnosis* / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005968:Glutamate Decarboxylase / Q000172:deficiency*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D011736:Pyridoxine / Q000008:administration & dosage*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; D011736:Pyridoxine