Accentuated cortico-cortical evoked potentials in neocortical epilepsy in areas of ictal onset

Masaki Iwasaki, Rei Enatsu, Riki Matsumoto, Eric Novak, Baburaj Thankappen, Zhe Piao, Tim O'Connor R, Karl Horning, William Bingaman, Dileep Nair

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)


Objective. To determine whether patients with neocortical epilepsy show evidence for increased excitability measured by cortico-cortical evoked potentials (CCEPs) in ictal-onset regions. Methods. In patients undergoing intracranial recordings with subdural electrodes for epilepsy surgery, we measured amplitudes, latencies, and stimulus thresholds of CCEPs near ictal onset zones (iCCEPs), and compared with adjacent neocortex not associated with ictal EEG (nCCEP). CCEP amplitude and latency measurements were made with each stimulation site, using graded stimulation intensities. Results. Ten patients were included in this study. CCEPs were recorded in eight of 10 patients. The first negative (N1) iCCEP amplitude was higher than that of nCCEP in seven of the eight patients. In the group analysis, this difference was statistically significant. In three of these patients, the difference was individually significant. In one patient, the amplitude was higher in nCCEP than iCCEP and the area selected as nCCEP was within primary eloquent cortex. There was no significant difference seen in latency changes or stimulus threshold. Conclusions. Accentuated CCEP amplitudes near ictal onset zones could reflect an increased excitability of the cortex associated with the epileptogenic zone in some patients with neocortical epilepsy. The response of the neocortex to low-frequency stimulation may vary depending on the presence or absence of intrinsic epileptogenicity.

Original languageEnglish
Pages (from-to)292-302
Number of pages11
JournalEpileptic Disorders
Issue number4
Publication statusPublished - 2010 Dec


  • Cortical stimulation
  • Epilepsy
  • Evoked potentials
  • Ictal-onset zone
  • Low frequency stimulation
  • Subdural electrode

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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