OBJECTIVETo analyze clinical characteristics, treatment and prognosis in a cohort of children with vitamin B6 responsive infantile spasms.

METHODTen patients were diagnosed as vitamin B6 responsive infantile spasms in Peking University First Hospital between January 2012 and May 2015.The clinical manifestations, diagnosis and treatment process, video-electroencephalogram, magnetic resonance imaging (MRI), epilepsy related genes and prognosis were retrospectively analyzed.

RESULTOf the 10 patients, 5 were male, and 5 were female. Eight of them were normal at birth, and the other 2 patients had intracranial hemorrhage or anoxia.The age of epilepsy onset was from 3.5 to 8.0 months.All patients presented spasms primarily.Interictal electroencephalogram (EEG) showed hypsarrhythmia at seizures onset. MRI showed normal in 8 patients, and subarachnoid hemorrhage or multiple encephalomalacia foci after hemorrhage respectively in the other 2 patients. The results of blood biochemical, cerebrospinal fluid examination and urinary metabolic screening were negative. Epilepsy related genes including ALDH7A1 gene analysis showed wild type in all patients. Two patients were classified as symptomatic and eight might be idiopathic or cryptogenic. The initial dose of vitamin B6 was 10.0 mg/(kg·d). The interval between seizures onset and taking vitamin B6 was 0 to 4.0 months. Seizures disappeared completely within a week after administration of vitamin B6 in 9 patients and in 1.5 months in one patient.Of the 8 patients whose seizures were controlled completely during the follow-up period, 7 patients' EEG recovered within 1.5 to 4.0 months and then continued to be normal. The EEG of the rest of a patient returned to normal, but showed abnormal discharges after stopping taking vitamin B6. Two patients' EEG continued abnormal and seizures recurred due to vitamin B6 withdrawal. At the last follow-up, seizures were controlled in all patients. Drug treatment in one case had stopped. Vitamin B6 was used in 9 patients at a dose of 0.4 to 10.0 mg/(kg·d). Among them, vitamin B6 monotherapy or coadministration with one low dose antiepileptic drug was applied in 6 or 3 patients respectively. The psychomotor development was normal in 5 patients, mild delay in 3 patients, and severe delay in 2 patients with autism behavior. Of the 2 symptomatic patients, one developed normally and the other showed severe delay.

CONCLUSIONVitamin B6 might have effects on both idiopathic or cryptogenic and symptomatic patients, especially for the former. High dose vitamin B6 should be first tried in all patients with infantile spasms. Patients who had response to vitamin B6 could be controlled within a short time and might have better outcomes. Seizures were not easy to relapse in those whose seizures were controlled and EEG recovered completely. Vitamin B6 could be gradually reduced during the course and might be withdrawn in the future. The recurrence of seizures was closely related to EEG abnormality.