Metabolic Syndromes in Neurology

A 6-year-old boy presented to the outpatient department for acute-onset visual disturbances. He was born full term with a normal birth weight and normal delivery out of a non-consanguineous marriage. His birth and perinatal history were uneventful, but he had a mild gross motor developmental delay. He started to have recurrent vomiting at 3 years of age, unrelated to feeding. He happened to be sleepy, less interactive and lethargic most of the time since 4 years of age. Recently after a febrile episode, he developed difficulty recognising family members though he could identify them by voice. His speech became slurred and had one episode of generalised tonic-clonic seizure.