10 Epidemiology of Pyridoxine-Dependent Seizures in the Netherlands

Abstract

Top of pageAbstract Background: Pyridoxine-dependent epilepsy is a rare cause of seizures in childhood and epidemiologic data on pyridoxine dependency are scarce. Classically, the diagnosis is definitely established when convulsions recur after withdrawal of pyridoxine and cease again after a second trial of pyridoxine (Baxter P. Pyridoxine-dependent and pyridoxine-responsive seizures. Dev Med Child Neurol 2001:416–20). Objectives: To study the epidemiology of pyridoxine-dependent epilepsy in the Netherlands, and to determine whether the diagnosis is based upon the appropriate criteria. Methods: Nationwide all university hospitals (n=10) and departments of paediatric or neonatal neurology (n=17) were asked to report known cases of pyridoxine-dependent seizures. Birth incidences were calculated using national data on life births from 1991 to 2003. The criteria of definite, probable, and possible cases of pyridoxine-dependent seizures were applied as published by Baxter (Baxter P. Epidemiology of pyridoxine dependent and pyridoxine responsive seizures in the UK. Arch Dis Child 1999:431–3). Results: Response was received from all 10 university hospitals and 94% of paediatric or neonatal neurology departments. Thirteen patients were reported. Five definite (38%), two probable (15%), and four possible cases (31%) were identified. Two cases (15%) did not meet criteria for either of these groups. The birth incidence was 1:396 000 for definite and probable cases and 1:252 000 when possible cases are included. Conclusions: Thus far, epidemiologic data on pyridoxine-dependent seizures were only available from the UK and Ireland. A higher incidence is found in the Netherlands, in accordance to earlier suggestions of a regional difference. The study shows that the diagnosis is often made without performance of a formal trial of withdrawal. We want to emphasize the importance of confirming the diagnosis, concerning the consequences as for individual prognosis, the potential side effects of prolonged pyridoxine substitution, and the possibility of treating the mother in case of future pregnancies.