Acute infantile encephalopathy predominantly affecting the frontal lobes (AIEF): a novel clinical category and its tentative diagnostic criteria

Acute infantile encephalopathy predominantly affecting the frontal lobes (AIEF) is proposed as a novel form of acute encephalopathy in infancy. To establish the diagnostic criteria for AIEF, we reviewed the clinical data of 10 patients who were seen by us and diagnosed as having AIEF, and those of 7 patients in the literature compatible with the diagnosis of AIEF. The mean age of onset was 1 year and 7 months. Boys and girls were equally affected. There is always an association with hyperpyrexia due to viral illness. Manifestations at the onset were convulsive status epilepticus and prolonged coma followed by signs of frontal lobe dysfunction such as a lack of spontaneity and regression of verbal functions. Imaging studies demonstrated edematous changes of the bilateral frontal lobes, which showed increased cerebral perfusion initially but attenuated perfusion several weeks later. The recovery of intellectual deficit was generally slower than that of motor disability. Based on these findings, we propose tentative diagnostic criteria of AIEF.