Accuracy and initial outcomes for stereotactic laser amygdalohippocampotomy using a fully MRI-compatible platform.

Objective: Minimally invasive MRI-guided laser interstitial thermal therapy (MRgLITT) is an approach increasingly recognized as an effective tool for treating epileptic foci. Recent literature reports that stereotactic laser amygdalohippocampotomy (SLAH) for mesial temporal lobe epilepsy (MTLE) results in seizure-freedom rates comparable to those of analogous open selective amygdalohippocampectomy with a potentially more favorable neurocognitive adverse effect profile. However, many SLAH series show heterogenous results. The authors' objectives were to present the largest experience to date using a single MRI-compatible targeting platform (ClearPoint) for SLAH to treat MTLE and to report their analysis of accuracy and intraoperative factors correlated to complications and initial outcomes.

Methods: The authors retrospectively collected data from all consecutive patients who underwent SLAH for MTLE using a single MRI-compatible targeting platform (ClearPoint) for SLAH at Emory University between June 2013 and October 2019. Univariable analysis, including the Student t-test, 1-way ANOVA, chi-square test, and Wilcoxon rank-sum test, was used to assess the relationship between surgical characteristics and outcomes.

Results: The authors analyzed a total of 91 patients who underwent 97 procedures with 114 total trajectories between June 2013 and October 2019. All patients had a diagnosis of MTLE, as determined by scalp or intracranial EEG, with a mean ± SD age at surgery of 42.8 ± 12.9 years and a mean seizure onset age of 19.3 ± 14.7 years. The mean number of trajectories was 1.39 ± 0.6 (range 1-3), with an overall mean target error of 1.2 ± 1.0 mm (range 0.1-4.7 mm). Target errors improved significantly over time, demonstrating a learning effect. Entry-to-target distance was 106.5 ± 11.5 mm (range 62.6-127.3 mm) and did not correlate to error. At the 12-month follow-up, 46 (50.5%) had an Engel score I, 21 (23.1%) had an Engel score II, 16 (17.6%) had an Engel score III, 5 (5.5%) had an Engel score IV, and 3 were lost to follow-up. Of the 66 patients who had mesial temporal sclerosis (MTS), 38 (56%) had Engel score I, 15 (23%) had score II, 9 (14%) had score III, and 3 (4.5%) had score IV at 12 months, with 1 lost to follow-up. Of the 25 patients without MTS, 8 (32%) had Engel score I, 6 (24%) had score II, 7 (28%) had score III, and 2 (8.0%) had score IV at 12 months, with 2 lost to follow-up.

Conclusions: The authors present the largest single-center experience using an MRI-compatible targeting platform for initial SLAH to treat MTLE. This technique results in safe laser ablation of epileptogenic tissue, with seizure outcomes comparable to those reported for open procedures. Further work is needed to validate its advantages over existing stereotactic approaches and the impact of multiple minimally invasive procedures.