Subdural EEG Patterns in Children With Taylor-Type Cortical Dysplasia: Comparison With Nondysplastic Lesions

Abstract

The authors compared interictal and ictal abnormalities from chronic intracranial recordings in children with Taylor-type cortical dysplasia (TTCD) and nondysplastic lesions. Interictal epileptiform discharges and ictal patterns were retrospectively analyzed in 13 children with TTCD and 12 children with nondysplastic lesions (tumor, 4; gliosis, 8). Features analyzed and compared between groups included the morphologic and temporal characteristics and field distribution of ictal and interictal patterns and rapidity of ictal propagation. The frequency of runs of interictal continuous epileptiform discharges (CEDs) or bursts of fast activity did not differ significantly between dysplastic and nondysplastic tissue. Fast frequencies characterized the majority of seizure onsets (49/67) in dysplastic patients and repetitive spikes were more frequent at seizure onset (31/56) in nondysplastic patients (P < 0.002). Field of ictal onset was limited to adjacent cortex and independent of histology. The interval between seizure onset and spread to adjacent or nonadjacent cortex was significantly shorter in dysplastic than nondysplastic patients. Interictal EEG patterns are not specific markers of dysplastic cortex but the morphology of ictal onset differs significantly with dysplastic cortex showing significantly more rapid propagation than nondysplastic cortex. These findings suggest that markers other than CEDs physiologically characterize dysplastic cortex and that children with TTCD exhibit more widespread excitability of neural pathways.

Surgery for medically intractable temporal lobe epilepsy during early life

“…It is also possible that rapid propagation to motor pathways occurs through aberrant neural networks. We have previously observed that cortical dysplasia is associated with more rapid spread of epileptic discharges compared to other pathological substrates (Turkdogan et al, 2005).…”

Incomplete resection of focal cortical dysplasia is the main predictor of poor postsurgical outcome

“…[23][24][25] In patients undergoing intraoperative electrocorticography, regions of active spiking with consistent focality, exhibiting rhythmic features such as trains of focal fast activity, or associated with focal attenuation of background were considered significant and resected. Infrequent spikes and spikes without consistent focality were ignored.…”

Subdural electrode analysis in focal cortical dysplasia

“…20 Interictal and ictal paroxysmal fast activity is reported to be more specific for FCD than other pathologies. [27][28][29] A characteristic bursting or continuous/quasi-continuous and localized pattern of epileptiform discharges on ECoG has been associated with recording from the surface of the FCD lesion. In 12 of 18 cases in which there was a complete resection of this pattern, there was a successful outcome.…”