Abstracts

Rationale: Epilepsy surgery is a widely accepted treatment for drug resistant epilepsy patients. However, surgery for bilateral lesions remains a challenge, and data remain limited. Here, we reviewed patients who had bilateral lesions and underwent epilepsy surgery

Methods: This study was conducted at Severance Children’s Hospital between 2003 and 2020. Patients who had bilateral structural lesions on brain magnetic resonance imaging, diagnosed with drug resistant epilepsy, underwent epilepsy surgery, aged ≤ 18 years old, were included. Engel’s classification was used to assess seizure outcome at 1year, 2years, 5years after surgery. Factors related to postoperative outcomes were investigated.

Results: Seventy-nine patients (Male: Female, 45(56%):34(44%)) were included. The median age of seizure onset was 0.88 (Interquartile Ratio(IQR) 0.28-4.67) years; median epilepsy duration was 5.26 (IQR 2.12-11.64) years; median age at surgery was 9.14 (IQR 5.75-14.29). Patients underwent multi-lobar resection (57/79, 72.2%), unilateral extra-temporal resection (16/79, 20.3%), and unilateral temporal resection (6/79, 7.6%). Seven (8.9%) patients had a past surgical history of corpus callostomy. Fifty-four (68.4%) patients had focal epilepsy; 19 (24.1%) patients had Lennox-Gastaut Syndrome, 4 (5%) patients had Infantile Spasm.

Thirty-seven (46.8%) patients had tuberous sclerosis; 11 (13.9%) patients had focal cortical dysplasia; 8 (10%) patients had other malformation of cortical development; 5 (6.3%) patients had hippocampal sclerosis.

At 1-year follow up, post-operative seizure outcome was Engel class I in 34 (43%) patients, Engel class II in 10 (13%) patients, Engel class III in 21 (27%) patients, and Engel class IV in 14 (18%) patients. At 2-year and 5-year follow up, 33 (50%) of 66 patients, 22 (48%) of 46 patients had Engel class I.

Eight patients underwent bilateral resection, and at 1-year follow up, seizure outcome was Engel class I in 2 (25%) patients, Engel class II in 1 (13%) patient, Engel class III in 5 (63%) patients, Engel class IV in none. At 2-year and 5-year follow up, seizure outcome was Engel class I in 2 (40%) of 5 patients.

Seventy-two patients underwent unilateral resection, and at 1-year follow up, seizure outcome was Engel class I in 32 (45%) patients, Engel class II in 9 (13%) patients, Engel class III in 16 (23%) patients, Engel class IV in 14 (20%) patients. At 2-year and 5-year follow up, seizure outcome was Engel class I in 31 (51%) of 61 patients, 20 (49%) of 41 patients, respectively.

In multivariate analysis, epilepsy duration (p=0.0197), location of the resection surgery (p=0.0313), were significantly associated with seizure freedom at 1-year follow up.

Conclusions: Approximately half of the patients who had bilateral structural lesions achieved seizure freedom with epilepsy surgery. Bilateral lesions on brain MR imaging should not hinder resective epilepsy surgery.

Funding: Please list any funding that was received in support of this abstract.: Severance Children’s Hospital, Yonsei University College of Medicine, Seoul, Korea.