LAUSR

Pyridoxine‐dependent epilepsy (PDE) is a genetic metabolic disease caused by inborn errors affecting vitamin B6 metabolism, which typically presents with neonatal seizures resistant to antiepileptic drugs (AEDs). Treatment with pyridoxine terminates seizures and prevents neurological decline. We describe a case in which the diagnosis was established at the age of 22 years. Birth and development were normal, but there was a history of three isolated tonic‐clonic seizures during childhood and adolescence. At the age of 18 years, she developed frequent focal motor seizures, many evolving into tonic‐clonic seizures. Electroencephalography identified a focus in the posterior right hemisphere, but magnetic resonance imaging of the brain was normal. Over the next 3 years, she was hospitalized with uncontrolled seizures on six occasions and spent a total of 121 days in intensive care. The seizures proved resistant to 12 different AEDs. Exome sequencing revealed two pathogenic mutations in ALDH7A1. Since starting on pyridoxine 50 mg once daily, she has been seizure‐free, all AEDs have been withdrawn, and cognition has improved to premorbid levels. This case illustrates the importance of considering PDE in drug‐resistant epilepsy in adults.