Abstracts

This study sought to characterize epileptic phenotypes in children with nonspecific mitochondrial disease (MD) and to evaluate MD diagnostic approaches. A retrospective analysis of the medical, EEG and laboratory records of 142 patients with childhood epilepsy was performed. The patients were evaluated for MD, and 124 patients were included in the final cohort. The MD criteria used included an oral glucose lactate stimulation test (OGLST) and urine organic acid/plasma amino acid (UOA/PAA) assays as metabolic indicators of modified Walker criteria, as suggested by Bernier [italic]et al.[/italic] 45 patients showed metabolic results which prompted further study using histologic, enzymologic and molecular techniques. Twenty-two patients were classified as having definite MD (9), probable MD (5), possible MD (6) or pyruvate dehydrogenase (PDH) deficiency (3), including one patient which showed a respiratory chain (RC) defect and PDH deficiency. Seven out of eight patients in whom significant RC defects were observed showed complex I defects. Epileptic diagnoses were heterogeneous; repeated seizures were the first unequivocal neurologic sign in 16 patients. In 14 patients, epileptic seizures onset at infantile ages. Photoparoxysmal responses were observed in only three patients. Of 17 patients who substantially presented generalized seizures, four patients started with partial seizures. Five patients consistently presented only partial seizures. The OGLST and UOA/PAA assays were often useful for a more precise diagnosis of MD. A wide and heterogeneous spectrum of epileptic phenotypes in the patients suggests that MD may be suspected in any epileptic child with progressive and fluctuating clinical courses.