[Influenza-associated encephalopathy with onset of prolonged convulsion: a case report]

A 1-year-old girl with influenza-associated encephalopathy initially exhibited prolonged febrile convulsions and subsequent drowsiness. She became unconsciousness and experienced a cluster of seizures 4 days later. Diffusion-weighted magnetic resonance imaging (DWI) showed high signal intensity in the bilateral frontal white matter. This signal change migrated to the bifrontal cortical areas and the caudate nuclei within 10 days, when T2 elongation appeared over the gray and white matter of frontal lobes. Choreoathetosis and oculogyric crisis were transiently noted at this period. Frontal lobe signs, including the forded mouth opening response, after diminution of these movement disorders. The DWI signal change subsequently resolved and frontal cortical atrophy appeared thereafter. Levels of inflammatory cytokines in the cerebrospinal fluid were normal during the acute phase of clinical course. The biphasic clinical course with initial prolonged seizure, involvement of the frontal lobes, and the progression of signal change on DWI from white to gray matter, meets the characteristics of "status epilepticus-type acute encephalopathy" suggested by Shiomi et al. Although pentobarbital infusion, steroid pulse therapy and mild hypothermia did not show any apparent effects on the clinical course of this patient, further trial of these therapies may be warranted for the treatment of this type of encephalopathy.