Abstracts

Rationale: Laser interstitial thermal therapy (LITT) has emerged as a minimally invasive surgical option
for temporal lobe epilepsy (TLE), offering an alternative to traditional craniotomy approaches. This study
evaluates the outcomes of 1-filament vs. 2-filament LITT in patients with mesial temporal lobe epilepsy
(mTLE).

Methods: We conducted a retrospective chart review of patients who underwent LITT ablation of the
mesial temporal lobe from 2015 to 2022 at our institution. Seizure outcomes were compared using the
Engel classification system for patients who underwent LITT with 1- vs 2-filaments. Any Engel class 1 was
considered a good outcome. The primary outcome was assessed using Kaplan-Meier survival analysis
assessing Engel 1 vs non-1 outcomes and Engel 1a vs. non-1a outcomes. We also examined the timing
of the first event reported, the need for a second procedure, and its timing. Additionally, we analyzed the
association of various factors such as etiology (mesial temporal sclerosis [MTS] vs. non-MTS), PET, prior
stereo electroencephalography (SEEG) use, MRI and SPECT results, and acute complications during
hospital stay.

Results: Forty-eight patients (21 females [43.8%], 27 males [56.3%]) underwent LITT ablation for
refractory mTLE, with indications including MTS in 29 (60.4%) and non-MTS in 19 (39.6%) cases. SEEG-
guided the ablation target in 21 patients (43.8%). Eleven patients had repeat procedures, 9 patients with
double trajectories, seizure free at 3 years was 65% (95% CI 47-89) and 85% (95% CI 49-100 in single
and double trajectories respectively. PET imaging was associated with a lower non-significant risk of a
repeat procedure, HR=3.8, 95% CI 0.99-14.2, p=0.051), suggesting potential predictive value for
treatment outcomes.
Thirty-four patients achieved any Engel 1 classification at last follow up (K-M estimate of any Engel 1
outcome at 3 years 50%, 95% CI 34-69). The two-filament approach was associated with a non-
significant lower risk of any Engel 2-4 outcome (HR=0.5, 95% CI 0.2-1.3, p=0.16). Prior SEEG was
associated with a significant increased risk of an Engel 2-4 outcome (HR=2.4, 95% CI 1.1-5.6, p=0.04),
suggesting a higher likelihood of epilepsy complexity.
Fourteen patients had an Engel 1a outcome at last follow up. The median time to an Engel outcome
worse than 1a was 23 months (34 patients; K-M estimate at 3 years 24%, 95% CI 11-47 months?). The
two-filament approach was associated with a significantly lower risk of non-1a Engel outcome (HR=0.4,
95% CI 0.2-0.8, p=0.017.
Visual deficits, while reported as a common complication after LITT, were not prevalent in our cohort.

Conclusions: LITT ablation demonstrates safety and efficacy in the treatment of refractory mTLE. A 2-
filament approach may be more likely to result in a Engel 1a seizure outcome compared to a 1-filament
approach. Prior SEEG may indicate more complex patient profiles warranting careful consideration.

Funding: None