Laser interstitial thermal therapy for medically intractable mesial temporal lobe epilepsy

Abstract

SUMMARYObjective: To describe mesial temporal lobe ablated volumes, verbal memory, and surgical outcomes in patients with medically intractable mesial temporal lobe epilepsy (mTLE) treated with magnetic resonance imaging (MRI)-guided stereotactic laser interstitial thermal therapy (LiTT). Methods: We prospectively tracked seizure outcome in 20 patients at Thomas Jefferson University Hospital with drug-resistant mTLE who underwent MRI-guided LiTT from December 2011 to December 2014. Surgical outcome was assessed at 6 months, 1 year, 2 years, and at the most recent visit. Volume-based analysis of ablated mesial temporal structures was conducted in 17 patients with mesial temporal sclerosis (MTS) and results were compared between the seizure-free and not seizure-free groups. Results: Following LiTT, proportions of patients who were free of seizures impairing consciousness (including those with auras only) are as follows: 8 of 15 patients (53%, 95% confidence interval [CI] 30.1-75.2%) after 6 months, 4 of 11 patients (36.4%, 95% CI 14.9-64.8%) after 1 year, 3 of 5 patients (60%, 95% CI 22.9-88.4%) at 2-year followup. Median follow-up was 13.4 months after LiTT (range 1.3 months to 3.2 years). Seizure outcome after LiTT suggests an all or none response. Four patients had anterior temporal lobectomy (ATL) after LiTT; three are seizure-free. There were no differences in total ablated volume of the amygdalohippocampus complex or individual volumes of hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, and fusiform gyrus between seizure-free and non-seizure-free patients. Contextual verbal memory performance was preserved after LiTT, although decline in noncontextual memory task scores were noted. Significance: We conclude that MRI-guided stereotactic LiTT is a safe alternative to ATL in patients with medically intractable mTLE. Individualized assessment is warranted to determine whether the reduced odds of seizure freedom are worth the reduction in risk, discomfort, and recovery time. Larger prospective studies are needed to confirm our preliminary findings, and to define optimal ablation volume and ideal structures for ablation.

Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy for Treatment of Drug-Resistant Epilepsy

“…Patients with MTS had slightly higher rates of seizure freedom than patients without MTS (61% vs 53%) at 6 months, but this was not a statistically significant difference. At Thomas Jefferson University Hospital, we observed that about 40% of the 20 patients who underwent LiTT for MTLE were free of disabling seizures at 2 years [7]. The number of patients as too small for us to compare outcome between patients with and without MTS, but only 1 of the 3 patients without MTS was seizure-free after LiTT.…”

“…A disposable cooling catheter cools the laser fiber and surrounding tissues to minimize carbonization [6]. Most epilepsy centers set the target cytotoxic temperature between 60°C and 80°C and multiple ablations (2-3) are performed for selective laser amygdalohippocampectomy [7]. The thermal image is used to approximate the volume ablated or Bdamage zone^ [8].…”

“…In 2012, Curry and his team at Texas Children's Hospital [12] first reported the feasibility and efficacy of MRI-guided LiTT in ablating epileptic lesions in 5 pediatric patients. Since then, laser has been used to ablate a variety of epileptogenic lesions, including periventricular nodular heterotopia [13], tuberous sclerosis [14], cortical dysplasia [12,14], insular encephalomalacia [15], hypothalamic hamartomas (HH), and MTLE [7,12,16,17]. Although the literature on outcomes is limited to a handful reports, MRguided LiTT is a promising treatment alternative to open resections in patients with MTLE and HH.…”

“…Seizure freedom after LiTT in MTLE at 1 to 2 years ranges from 40% to 60%, with higher rates of seizure freedom seen in patients with MTS on MRI [7,17]. In 2014, Willie et al [17] published the results of LiTT therapy in 13 patients who underwent stereotactic laser amygdalohippocampotomy (SLAH) for medically intractable MTLE.…”

Advancements in Stereotactic Epilepsy Surgery: Stereo-EEG, Laser Interstitial Thermotherapy, and Responsive Neurostimulation

“…15 Our own institutional experience has demonstrated similar results, with 53% seizure freedom at 6 months, 36.4% at 1 year, and 60% at 2-year follow-up (loss to follow-up in a small patient sample resulting in the variable results within the study period). 18 Results 17 Intra-operatively, a manual arc-ring system is used with the CRW frame to guide placement of the anchor bolt, instead of the robotic system, given the time involved setting up the robot is not justified for a single trajectory. After drilling placement of a bone anchor bolt, a laser probe is advanced to target.…”