From swelling to sclerosis: acute change in mesial hippocampus after prolonged febrile seizure.

Mesial temporal sclerosis (MTS) has been linked to prolonged febrile seizures. The sequence of changes in the temporal lobe/hippocampus following prolonged febrile seizures and status epilepticus is beginning to be elucidated. We obtained repeated magnetic resonance imaging (MRI) volumetric analysis of the hippocampi in a 23-month-old boy after a prolonged focal febrile seizure. Three days after a prolonged left focal febrile seizure, brain MRI showed increased T2 weighted signal and increased volume (swelling) of the right hippocampus. Repeat MRI 2 months later demonstrated sclerosis of the right hippocampus. Review of the literature shows four other children with prolonged focal seizures associated with the MRI sequence of temporal lobe swelling followed by sclerosis. All had left focal seizures followed by right MTS. Our patient demonstrates a shorter interval for the radiologic development of hippocampal sclerosis compared to other reports.