RT Journal Article SR Electronic T1 Diffusion MRI abnormalities after prolonged febrile seizures with encephalopathy JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP 1304 OP 1309 DO 10.1212/01.wnl.0000210487.36667.a5 VO 66 IS 9 A1 Takanashi, J. A1 Oba, H. A1 Barkovich, A. J. A1 Tada, H. A1 Tanabe, Y. A1 Yamanouchi, H. A1 Fujimoto, S. A1 Kato, M. A1 Kawatani, M. A1 Sudo, A. A1 Ozawa, H. A1 Okanishi, T. A1 Ishitobi, M. A1 Maegaki, Y. A1 Koyasu, Y. YR 2006 UL http://n.neurology.org/content/66/9/1304.abstract AB Background: Patients with encephalopathy heralded by a prolonged seizure as the initial symptom often have abnormal subcortical white matter on diffusion-weighted MRI (DWI). Objective: To determine if these patients share other common features. Methods: Patients with encephalopathy heralded by a prolonged seizure and followed by the identification of abnormal subcortical white matter on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed. Results: Seventeen patients were identified, ages 10 months to 4 years. All had a prolonged febrile seizure (longer than 1 hour in 12 patients) as their initial symptom. Subsequent seizures, most often in clusters of complex partial seizures, were seen 4 to 6 days after the initial seizure in 16 patients. Outcome ranged from almost normal to severe mental retardation. MRI performed within 2 days of presentation showed no abnormality. Subcortical white matter lesions were observed on DWI between 3 and 9 days in all 17 patients. T2-weighted images showed linear high intensity of subcortical U fibers in 13 patients. The lesions were predominantly frontal or frontoparietal in location with sparing of the perirolandic region. The diffusion abnormality disappeared between days 9 and 25, and cerebral atrophy was detected later than 2 weeks. Three patients having only frontal lesions had relatively good clinical outcome. Conclusions: Although the pathophysiologic mechanism remains unknown, these patients seem to have a distinctive encephalopathy syndrome. MRI is helpful in establishing the diagnosis of this encephalopathy.