Abstracts

Rationale: Pyridoxine Dependent Epilepsy (PDE) is defined by therapy resistant seizures that respond to intravenous administration of pyridoxine (pyridoxine-IV). Identification of an important PDE subgroup occurs by increased urine α-AASA excretion and is confirmed by ALDH7A1gene mutation analysis. For prognostic reasons, it is recommended that all infants with therapy resistant seizures receive pyridoxine until PDE is excluded. In the present study, we aimed to investigate whether specific EEG responses upon pyridoxine-IV allow instantaneous recognition of PDE by ALDH7A1gene-mutation. Methods: Online EEG registrations of 50 mg pyridoxine-IV were compared between PDE [ALDH7A1gene-mutation (n=3, 6 trials)] and non-PDE (n=9, 9 trials). Urine-α-AASA concentrations were >9 mmol/mmol creat (PDE) and <1 (non-PDE). 5-15 minutes before and after pyridoxine-IV, EEG segments were digitally analyzed for average background amplitude and total & relative power. Total power indicates the magnitude of background-activity per frequency-band. Relative power indicates the contribution of a frequency-band to the spectrum. Results: After pyridoxine-IV, epileptic activity persisted in 3/3 PDE and 8/9 non-PDE infants (5/6 versus 8/9 trials, respectively). Intra-individually, two PDE infants showed a large variation in amplitude responses between consecutive trials (-64 to 39% and -44 to -26%, respectively). In both PDE and non-PDE: 1/ pyridoxine-IV did not affect relative power; 2/ central amplitude decreased (5/6 PDE trials; -64 to 39% versus 8/9 non-PDE trials; -45 to 15%) and, 3/ total power decreased (PDE -56 to 41%; -71 to +31%; -66 to +2% and non-PDE -43 to 14%; -29 to 27%; -54 to 2%; p<0.05, in delta, theta and beta frequency bands, respectively). Conclusions: Pyridoxine-IV causes non-specific EEG responses that hamper instantaneous recognition of PDE by ALDH7A1gene-mutation. These data implicate that infants with therapy resistant seizures should continue to receive pyridoxine until PDE is excluded by metabolic and/or DNA analysis.