Abstracts

RATIONALE:Focal cortical dysplasia lesion (FCD) have been recognized with increasing frequency as a cause of medically intractable partial epilepsy. Rhythmic epileptiform discharges (REDs) and continuous epileptiform discharges (CEDs) have been found to be highly specific indicator of FCD. OBJECTIVE: The purpose of this study is to determine the character and localizing value of ictal and interictal EEG in patients with the histopathological diagnosis of FCD METHODS: We retrospectively reviwed the medical records of 14 patients with the histophatologic diagnosis of FCD and intractable epilepsy. We analyzed interictal and ictal recordings to identify any particular pattern associated with FCD. RESULTS: 14 patients between the age of 6 months and 42 years were studied. The mean age for onset of epilepsy was 6 years (range 1 day to 39 years), and the mean age at epilepsy surgery was 16 years (range 6 months to 42 years). Eight patients had frontal lobe epilepsy, 3 had parietal lobe epilepsy, 2 had occipital lobe epilepsy and one patient had temporal lobe epilepsy. MRI abnormalities were found in 12 of 14 patients. The interictal EEG was characterized by isolated sharp waves or spikes in all cases. The spikes were limited to one region in 7 patients, and multiregional (2-5 regions) in 7. Five patients had bilateral and independents spikes. In addition generalized slow spike and wave complexes were seen in one patient. The ictal EEG was limited to 1 region in 11 patients, including 5/7 patients with multiregional interictal findings. In all cases the scalp ictal EEG correctly predicted the epileptogenic location on MRI/invasive monitoring. In three patients the ictal EEG was non-localizable. CONCLUSIONS: Our results suggets that isolated sharp waves or spikes are a common interictal finding in patients with FCD; REDs and CEDs were not seen in our series. Rather, our study suggests that regional ictal patterns are highly accurate in the localization of epilepsy due to FCD.