Abstract Details

Title Can We Accurately Lateralize the Epileptogenic Zone in Patients Who Have Seizure Clusters? A Study Using Stereoelectroencephalography (SEEG)

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) P1 - Poster Session 1 (12:00 PM-1:00 PM)

Poster/Presentation
Number 12-010

Objective To determine if the ictal onset (IO) recorded with SEEG during clusters of seizures is reliable to lateralize the epileptogenic zone (EZ).

Background In the presurgical evaluation of patients with focal refractory epilepsy, the presence of bilateral IO is usually associated with a poor post surgical outcome. It has been reported that recordings during clusters of seizures may result in false lateralization, although this remains controversial. Most of the studies have addressed the issue using scalp EEG which could erroneously determine the laterality of the IO.

Design/Methods We included all consecutive patients who underwent SEEG with bilateral hemispheric coverage at the London Health Sciences Centre (LHSC), Western University in London, Ontario, between January 2013 and September 2018. We assessed the presence of seizure clusters (clinical or electrographic) during SEEG evaluation. Certain clinical, imaging and electrographic characteristics were collected. Comparison was made between those who underwent surgery and those who did not.

Results A total of 143 patients underwent SEEG. Fifty nine had bilateral hemispheric electrode placement. Thirty two of these patients underwent resective surgery, but only 31 patients had at least 1 year of follow up. Of these 31 patients, 7 had bilateral IO and all of them had their discordant seizures during clusters. Of those with bilateral IO, 4 had temporal lobe epilepsy and were seizure free at 1 year of follow up. From the 27 patients who did not undergo surgery, 15 had bilateral IO. The group of patients with bilateral IO who were not submitted to surgery, because of presumed bad prognosis, had more discordant non cluster seizures (8) than those who had surgery (0), (p=0.022).

Conclusions All patients with discordant IO who were seizure free after epilepsy surgery had cluster seizures. Discordant IO during a seizure cluster does not necessarily suggests a contralateral EZ.

Authors/Disclosures
Miguel Arevalo Astrada PRESENTER	Miguel Arevalo Astrada has nothing to disclose.
Ana Suller Marti, MD (University Hospital London Ontario)	Dr. Suller Marti has nothing to disclose.
Richard McLachlan, MD	No disclosure on file
David C. Diosy, MD	Dr. Diosy has nothing to disclose.
Seyed M. Mirsattari, MD, PhD, FRCPC (Mayo Clinic)	Dr. Mirsattari has nothing to disclose.
	No disclosure on file
Jorge G. Burneo, MD, MSPH, FAAN (University of Western Ontario)	Dr. Burneo has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier, Clinical Neurology and Neurosurgery Journal. Dr. Burneo has received research support from The Jack Cowin Endowed Chair in Epilepsy Research. Dr. Burneo has received publishing royalties from a publication relating to health care. Dr. Burneo has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Jazz Pharmaceuticals.