Transient reduced diffusion in the cortex in a child with prolonged febrile seizures

We report on a 4-year-old boy with transient reduced diffusion in the cortex, thalamus, and hippocampus on diffusion-weighted imaging (DWI) performed after prolonged febrile seizures (PFS). He had experienced intermittent right hemiconvulsions lasting about 90 min during the febrile illness, but his neurological symptom resolved completely after several hours. DWI performed immediately after the PFS showed abnormally high signal intensities in the left extended cortex and pulvinar of the ipsilateral thalamus. Two days later, these DWI lesions resolved completely, but abnormally high signal intensities were observed in the left hippocampus. Three months later, the DWI was normal, and no atrophy or gliosis was seen. This patient had unique lesions on DWI after PFS, but it is nevertheless important to attend to such lesions on the DWI of patients with PFS.