Clustered subclinical seizures in a patient with acute encephalopathy with biphasic seizures and late reduced diffusion.

Using single-channel amplitude-integrated electroencephalography (aEEG), we monitored clustered seizures in a 12-month-old boy suffering from acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). He was admitted to our hospital after losing consciousness and experiencing repeated seizures in association with fever. Although the patient's state of consciousness improved the next day, it declined on the fifth day of illness, and clinical seizures were observed. Diffusion-weighted images revealed abnormal high intensities in the frontal area bilaterally. On the same day, aEEG monitoring revealed an unexpected cluster of subclinical seizures. Attending pediatricians, nurses, and other caregivers did not recognize the presence of these frequent subclinical seizures. The efficacy of antiepileptic drugs could also be objectively assessed from aEEG findings. aEEG is useful for continuous monitoring in children with acute encephalopathy, may disclose subclinical seizures, and can contribute to an objective evaluation of the efficacy of antiepileptic drugs.