Interictal regional polyspikes in noninvasive EEG suggest cortical dysplasia as etiology of focal epilepsies.
OBJECTIVE
To evaluate the clinical significance of interictal regional polyspikes in focal epilepsies secondary to cortical dysplasia.


METHODS
We performed a data search for the term "regional polyspikes" in the database of our epilepsy-monitoring unit. Patients with generalized epilepsies including Lennox-Gastaut syndrome were excluded. Regional interictal epileptiform discharges were recorded in 513 patients with noninvasive EEG.


RESULTS
We identified 29 patients with interictal regional polyspikes and focal epilepsies. Another 484 patients showed regional epileptiform discharges other than polyspikes. The etiology of the epilepsy was significantly more frequently cortical dysplasia in the group of patients with regional polyspikes (35%, 10 of 29 patients) than in the patients with other regional epileptiform discharges (5%, 24 of 484 patients) (p < 0.01). The polyspikes were significantly more frequently localized to the extratemporal (72%; n = 21) than temporal (28%; n = 8) regions (p < 0.01). In contrast, regional epileptiform discharges other than polyspikes were significantly more frequently localized to the temporal lobe (75%; n = 362) than extratemporal regions (25%; n = 122) (p < 0.01). Eight of the 10 patients with focal cortical dysplasia had extratemporal polyspikes.


CONCLUSIONS
Noninvasively recorded regional polyspikes suggest cortical dysplasias as etiology of predominantly extratemporal epilepsies.
Noachtar
Soheyl
S
Department of Neurology, Epilepsy Center, University of Munich, Munich, Germany. noa@med.uni-muenchen.de
Bilgin
Ozgür
O
Rémi
Jan
J
Chang
Nelly
N
Midi
Ipek
I
Vollmar
Christian
C
Feddersen
Berend
B
D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D054220:Malformations of Cortical Development / Q000175:diagnosis / Q000503:physiopathology*; D008875:Middle Aged; D049268:Positron-Emission Tomography; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology; D015899:Tomography, Emission-Computed, Single-Photon