A 9-year-old male with congenital bilateral perisylvian syndrome is described. He had pseudobulbar palsy, mental retardation, and intractable epilepsy. Computed tomography and magnetic resonance images of the brain demonstrated bilateral perisylvian malformations and a diffuse pachygyric appearance. At 8 years of age, he had episodes of excessive drooling, fluctuating impairment of consciousness, unsteady sitting, and frequent head drop that lasted several days. The electroencephalogram demonstrated continuous diffuse slow spike and waves. These findings suggested atypical absence status epilepticus. Intravenous administration of diazepam resulted in transient improvement of clinical and electroencephalographic findings. Status epilepticus recurred within several minutes after diazepam administration. Although no patient has been reported to have a history of status epilepticus among those affected by this syndrome, it seems that atypical absence status can occur more frequently than expected, as seen in Lennox-Gastaut syndrome. After recognition and confirmation of nonconvulsive status epilepticus, immediate treatment must be attempted.