Abstracts

Rationale: Laser interstitial thermal therapy (LiTT) provides a minimally invasive alternative to the traditional approach Anterior Temporal Lobectomy with Amygdalo-Hippocampectomy (ATL+AH) in Mesial temporal Lobe Epilepsy (mTLE). While LiTT is especially effective in minimizing loss of healthy eloquent cortex when compared to ATL+AH, the relatively decreased resective area also coincides with decreased seizure freedom in some patients, potentially necessitating subsequent ATL+AH procedures. Here, we assess the reasons for reoperation and the post-operative effects in patients who have undergone LiTT with subsequent ATL+AH.

Methods: A cohort of 75 patients (age 18-73, 41 males) underwent LiTT for intractable mTLE. Of these, 7 patients required subsequent ATL+AH procedures due to unsuccessful outcomes with continued seizure severity/frequency and were selected for further evaluation. All 7 patients underwent video EEG, and 6 of the patients underwent stereotactic electroencephalography (sEEG) for seizure foci localization prior to LiTT. The cause of LiTT failure was retrospectively determined by neurosurgical evaluation via comprehensive clinical chart review. Hemisphere language dominance was determined via Wada testing, functional MRI, or direct cortical stimulation, and seizure outcomes were measured using ILAE classifications. Neuropsychological data were also collected prior to and 6 months following surgery and evaluated for changes.

Results: In these 7 patients, the mean ILAE score following LiTT was 3.43±1.27, and the mean time between LiTT and ATL+AH procedures was 2.43 years (range: 0.44-3.48). The primary causes of reoperation included incomplete ablation of seizure focus (5 patients), followed by secondary epileptogenesis (2 patients). Following ATL+AH, 5 patients were classified as seizure free (ILAE = 1), and 2 patients continued to have significant seizure activity (ILAE 4, 5). No immediate surgical complications presented after either procedure in any patients. 3 of the patients underwent surgery on their language dominant hemisphere. Neuropsychological deficits in patients after LiTT included deficiencies in rote verbal memory/learning (4 patients) and semantic access/fluency (2 patients). When compared to postoperative LiTT testing, additional decreases after ATL+AH were noted in rote verbal memory/learning (4 patients), semantic access/fluency (1 patient), and expressive language (1 patient).

Conclusions: This study demonstrates the risks associated with LiTT regarding the need for further treatment of mTLE, especially in cases of inadequate coverage of ablation. In patients who required further resection with ATL+AH, a significant proportion achieved seizure freedom with limited morbidities. The greater potential efficacy of ATL+AH must be weighed against the increased risk of morbidity when determining the proper steps following failed LiTT of mTLE patients.

Funding: Please list any funding that was received in support of this abstract.: No funding was received in support of this abstract.