Prevalence, clinic-etiological spectrum and outcome of pediatric metabolic epilepsy - A single centre experience

Introduction: Inborn errors of metabolism (IEM) are a rare cause of epilepsy in pediatric age group. Prompt diagnosis is essential, as some of these disorders are treatable. Aim: To determine the prevalence, clinical, and etiological profile of metabolic epilepsy in children. Methods: A prospective observational study of children with new onset seizures diagnosed as inherited metabolic disorder in a tertiary care hospital, South India. Results: Among 10,778 children with new onset seizures, 63 (0.58%) had metabolic epilepsy. The male female ratio was 1.3:1. Onset of the seizures were in neonatal period in 12 (19%), infancy in 35 (55.6%), and between one and 5 years of age in 16 (25.4%) children. Generalised seizures were seen in 46 (73%), followed by multiple seizure types (31.7%). The associated clinical features included developmental delay in 37 (58.7%), hyperactivity in 7 (11%), microcephaly in 13 (20.6%), optic atrophy in 12 (19%), sparse hair and/or seborrheic dermatitis in 10 (15.9%), movement disorder in 7 (11%), and focal deficit in 27 (42.9%) patients. Magnetic resonance imaging brain was abnormal in 44 (69.8%) and diagnostic in 28 (44.4%) patients. Causative metabolic errors included vitamin responsive errors in 20 (31.7%), disorders of complex molecules in 13 (20.6%), amino acidopathies in 12 (19%), organic acidemias in 10 (16%), disorders of energy metabolism in 6 (9.5%), and peroxisomal disorders in 2 (3.2%) patients. With specific treatment, seizure freedom could be achieved in 45 (71%) children. Five children lost to follow-up and two died. Among the remaining 56 patients, 11 (19.6%) had a good neurological outcome. Conclusion: Vitamin responsive epilepsies were the most frequent cause of metabolic epilepsy. Early diagnosis and prompt treatment is necessary as only one-fifth had a good neurological outcome.