Abstracts

Rationale: Resective epilepsy surgery is commonly used for treatment of intractable epilepsy, but carries a failure rate of 22-24% (Engels 2-4).[1,2] Patients that fail initial resective surgery may require additional surgery to completely resect the epileptogenic zone. Repeat surgeries can be complicated by tissue scaring and surgically altered anatomy, potentially increasing the risk of open resection. Laser interstitial thermal therapy (LiTT) is a minimally invasive real-time MR-image guided surgical technique which allows targeted application of thermal energy to ablate cortical tissue. LiTT may offer an alternative treatment approach for appropriately selected patients that fail open resection. Methods: Data from the Comprehensive Epilepsy Surgery Program database of Cook Children’s Medical Center was reviewed to include all patients < 20 years that underwent LiTT following a previous failed open resection. Multiple pre-, peri-, and post-operative variables were collected and analyzed. Patients were characterized as seizure free (Engel 1) or not (Engel 2-4). Results: Fourteen patients met inclusion criteria. The average age of seizure onset was 3.09 years (0.3-11 y) with the initial surgical intervention occurring at 8.94 years (2-17 y). All patients had localization related epilepsy with lesional MRI in 8 (57%) prior to initial resection. Initial failed procedures included focal cortical resection in 8 (57%), lobectomy in 5(36%), and hemispherectomy in 1(7%). LiTT was performed at mean age 12.14 years (4-19 y), an average 3.2 years after the failed initial surgery. Prior to LiTT, all had additional evaluation including MRI in 14 (7 lesional), 13 (93%) VEEG, SPECT in 8 (57%), PET in 11 (79%), MEG in 10 (71%), and 5 (36%) had invasive eeg monitoring. LiTT was performed in the region of the prior resection in 9 (64%) cases while 5 (36%) targeted an epileptogenic zone separate from prior resection. At the time of last follow up (average 1 year, range 0.5-2 years), 43% were seizure free (Engel 1). Patients who initially underwent focal cortical resections had better post-LiTT outcomes (Engel 1, 57%) than patients who had lobectomy or hemispherectomy (Engel 1, 33%). Complications in 2 (14%) cases included transient transcortical aphasia and mild left facial palsy which did resolve. Conclusions: Following a failed open resection, LiTT resulted in seizure freedom in a significant proportion of patients with limited morbidity. Patients that failed focal open resection were more often seizure free post-LiTT than lobectomy/hemispherectomy patients, likely secondary to a more localized epileptogenic zone amenable to thermal ablation. While further prospective data is needed, this study suggests LiTT is a viable option for patients that have failed prior open resection and likely carries less morbidity. Funding: No funding was received for this project.