Focal cerebral pathology presenting as tonic seizures.

We report a case of a 14-year-old boy with a dysembryoplastic neuroepithelial tumor and mental retardation with intractable seizures, which were demonstrated to be predominantly tonic seizures by video-electroencephalography (EEG). He did not have any electrographic evidence of Lennox-Gastaut syndrome. Head magnetic resonance imaging (MRI) revealed a right parietal dysembryoplastic neuroepithelial tumor. He has been seizure free since surgical removal of the tumor. Clinicians need to be aware that tonic seizures can be associated with an underlying focal pathology that might be treatable.