Acute encephalopathy with biphasic seizures and late reduced diffusion with visual disturbance and higher brain dysfunction

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a recently described clinicoradiologic syndrome. Clinically, a prolonged febrile seizure is followed by subsequent seizures which occur several days after the initial seizure. On MRI, reduced diffusion appears predominantly in the frontoparietal subcortical white matter at the time of the subsequent seizures. The main symptom between the initial and subsequent seizures is disturbance of consciousness. We report a case with AESD who presented 1) reduced diffusion on MRI which was dominant in the occipital lobe, and 2) reversible visual disturbance followed by higher brain dysfunction such as a cognitive deficit and disturbed speech. A 2-year-old Japanese girl was admitted because of visual disturbance which appeared 4 days after a generalized tonic-clonic seizure associated with fever. Two days later, she had another seizure when MRI revealed reduced diffusion in the subcortical white matter. The MRI finding was not typical of AESD in that reduced diffusion appeared dominantly in the occipital lobe. Normal ophthalmologic findings and abnormal visual evoked potential results suggested that her visual disturbance was due to an impaired visual pathway in the subcortical white matter in the occipital lobe. The present case indicates that there is a subgroup of AESD in which the subcortical lesion seen on MRI is dominant in the occipital lobe.