Abstract
ObjectiveLaser interstitial thermal therapy (LITT) is a novel minimally invasive alternative to open mesial temporal resection in drug‐resistant mesial temporal lobe epilepsy (MTLE). The safety and efficacy of the procedure are dependent on the preplanned trajectory and the extent of the planned ablation achieved. Ablation of the mesial hippocampal head has been suggested to be an independent predictor of seizure freedom, whereas sparing of collateral structures is thought to result in improved neuropsychological outcomes. We aim to validate an automated trajectory planning platform against manually planned trajectories to objectively standardize the process.MethodsUsing the EpiNav platform, we compare automated trajectory planning parameters derived from expert opinion and machine learning to undertake a multicenter validation against manually planned and implemented trajectories in 95 patients with MTLE. We estimate ablation volumes of regions of interest and quantify the size of the avascular corridor through the use of a risk score as a marker of safety. We also undertake blinded external expert feasibility and preference ratings.ResultsAutomated trajectory planning employs complex algorithms to maximize ablation of the mesial hippocampal head and amygdala, while sparing the parahippocampal gyrus. Automated trajectories resulted in significantly lower calculated risk scores and greater amygdala ablation percentage, whereas overall hippocampal ablation percentage did not differ significantly. In addition, estimated damage to collateral structures was reduced. Blinded external expert raters were significantly more likely to prefer automated to manually planned trajectories.SignificanceRetrospective studies of automated trajectory planning show much promise in improving safety parameters and ablation volumes during LITT for MTLE. Multicenter validation provides evidence that the algorithm is robust, and blinded external expert ratings indicate that the trajectories are clinically feasible. Prospective validation studies are now required to determine if automated trajectories translate into improved seizure freedom rates and reduced neuropsychological deficits.
Highlights
Laser interstitial thermal therapy (LITT) is a novel minimally invasive technique for performing highly selective ablations within the brain[1] and spine.[2]
Contemporary series of LITT for mesial temporal lobe epilepsy (MTLE) have reported seizure‐freedom rates comparable to those for open neurosurgical resection,[3‒5] with some centers offering this as first‐line treatment.[6]
Consecutive patients were included if they had received LITT for MTLE and had concordant semiology, scalp electroencephalography (EEG) and structural magnetic resonance imaging (MRI) features of mesial temporal sclerosis, or had seizure onset confirmed within the hippocampus following stereo‐EEG (SEEG) investigation
Summary
Laser interstitial thermal therapy (LITT) is a novel minimally invasive technique for performing highly selective ablations within the brain[1] and spine.[2]. The highly selective nature of the thermal ablation has been suggested to result in less neuropsychological deficit as a consequence of limiting damage to collateral brain structures.[7,8]. The extent of the ablation and heat dissipation to surrounding brain structures is monitored using magnetic resonance (MR) thermography.[10]. LITT results in ablation diameters of 5‐20 mm in diameter and is susceptible to heat sinks such as cerebrospinal fluid (CSF) cavities and vasculature.[11]. The safety and efficacy of LITT for MTLE is dependent on the preplanned trajectory and the volume of the thermal ablation. Only a single study has suggested that the extent of the mesial hippocampal head ablation is an independent predictor of seizure‐free outcome.[12]. Given the lack of evidence defining optimal ablation parameters for a seizure‐ free outcome, neurosurgeons apply a number of heuristics
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