Seizure onset patterns predict outcome after stereotactic electroencephalography-guided laser amygdalohippocampotomy

Objective Stereotactic laser amygdalohippocampotomy (SLAH) is an appealing option for patients with temporal lobe epilepsy, who often require intracranial monitoring to confirm mesial temporal seizure onset. However, given limited spatial sampling, it is possible that stereotactic electroencephalography (sEEG) may miss seizure onset elsewhere. We hypothesized that sEEG seizure onset patterns (SOPs) may differentiate between primary onset and secondary spread and predict postoperative seizure control. In this study, we characterized the two-year outcomes of patients who underwent single-probe SLAH after sEEG and evaluated whether sEEG SOPs predict postoperative seizure freedom. Methods This retrospective five-center study included patients with or without mesial temporal sclerosis (MTS) who underwent sEEG followed by single probe SLAH between August 2014 and January 2022. Patients with causative hippocampal lesions apart from MTS or for whom the SLAH was considered palliative were excluded. A SOP catalogue was developed based on literature review. The dominant pattern for each patient was used for survival analysis. The primary outcome was two-year Engel I classification or recurrent seizures before then, stratified by SOP category. Results 58 patients were included with a mean follow-up duration of 39 ± 12 months after SLAH. Overall one-, two, and three-year Engel I seizure freedom probability was 54%, 36%, and 33% respectively. Patients with SOPs including low voltage fast activity or low frequency repetitive spiking had a 46% two-year seizure freedom probability, compared to 0% for patients with alpha or theta frequency repetitive spiking or theta or delta frequency rhythmic slowing (log rank test, p = 0.00015). Significance Patients who underwent SLAH after sEEG had a low probability of seizure freedom at two years, but SOPs successfully predicted seizure recurrence in a subset of patients. This study provides proof of concept that SOPs distinguish between seizure onset and spread and supports using SOPs to improve selection of SLAH candidates. Key Points ### Competing Interest Statement SAS serves as a consultant for Boston Scientific, Zimmer Biomet, Neuropace, Koh Young. GRC has received research support from Insightec. NPI serves as a consultant for CVS/Caremark. TL serves as the CEO for Neurotech Institute. HD has received research support from Engage therapeutics and UCB. PW has received research support from Medtronic, Neuropace and Bluerock. The remaining authors have no relevant conflicts of interest. ### Funding Statement Research in this manuscript was supported by the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institute of Health (AJM: T32 NS07153; CAS: R01 NS084142, NS110669, and RF1 MH114276), S.T. has received support from the Department of Veterans Affairs, VISN1 Veterans Health Administration (V1CDA2022-= 68). K.A.D has received support from R01 NS 116504 and R01 NS 125137. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The IRB of Columbia University Irving Medical Center gave ethical gave ethical approval for this work The IRB of The Hospital of University of Pennsylvania gave ethical approval for this work The IRB of Mass General Brigham gave ethical approval for this work The IRB of University of Texas-Southwestern gave ethical approval for this work The IRB of University of Chicago gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors