Letter: The American Society for Stereotactic and Functional Neurosurgery Position Statement on Laser Interstitial Thermal Therapy for the Treatment of Drug-Resistant Epilepsy

This is the authors' abstract. We don't add key points for this paper.

To the Editor: We commend Wu et al1 for their position statement on the use of magnetic resonance image–guided laser interstitial thermal therapy (MRgLITT) for management of drug-resistant epilepsy (DRE). Owing to the recent development of MRgLITT for mesial temporal lobe epilepsy (mTLE), data on long-term outcomes are limited. In mTLE treated with MRgLITT, approximately one-third of patients continue to experience seizures despite treatment.2 There is thus still a need to improve surgical candidate selection and to elucidate postoperative prognoses. The authors here review prognostic factors demonstrated to correlate with improved seizure control post-MRgLIT in the recent literature. In a retrospective study by Kim et al3 on patients with mTLE treated with MRgLITT, preoperative MRI-derived apparent diffusion coefficient (ADC) was found to predict seizure outcomes. In those with good seizure control after MRgLITT, higher ADC intensities were found in ablated regions including the hippocampus and amygdala.3 Kim et al3 suggested the use of ADC analysis preoperatively during patient selection for MRgLITT. Furthermore, targeting of regions with high ADC intensity in the mesial temporal region may help to improve rates of seizure control in MRgLITT.3 In patients with unilateral mesial temporal sclerosis, the presence of bilateral interictal epileptiform discharges was significantly associated with seizure recurrence while greater age at surgery was found to predict increased seizure freedom 1 year after MRgLITT.4 Such prognostic factors may be considered during patient selection. In a meta-analysis of 559 patients, outcomes of MRgLITT in the treatment of DRE were investigated.5 Visual field deficits were the most common complication to occur, specifically in patients with mTLE.5 MRI-defined lesions may yield better results in MRgLITT because improved outcomes occurred in cases of mTLE with mesial temporal sclerosis when compared with nonlesional cases.5 In comparison with extratemporal and temporal lobe epilepsies, laser ablation of hypothalamic hamartomas demonstrated the greatest rate of seizure freedom.5 In a pediatric case series of MRgLITT for treatment of large hypothalamic hamartomas, ablation volumes were overlaid on a high-resolution hypothalamic MRI atlas to anatomically localize ablations in relation to seizure outcomes.6 Ablation of subcortical structures including the paraventricular nucleus, posterior hypothalamus, zona incerta, fornix, and mammillothalamic tract resulted in freedom of seizures.6 Such areas may be surgically targeted during MRgLITT, with utility of high-resolution MRI atlas alongside to help localize affected regions and to identify tissues that may be disrupted during ablation.6 In a pediatric case series of epilepsy related to periventricular nodular heterotopia, all patients experienced a decrease in seizure frequency, with complications including quadrantopia, hemianopia, and delayed intraparenchymal hemorrhage resulting in hemiparesis.7 For corpus callosotomy using MRgLITT for treatment of pediatric DRE, 71% of patients had resolution of drop attacks on long-term follow-up with no persistent functional deficits.8 Further investigation is required to establish factors associated with increased reoperation rate, increased seizure frequency post-treatment, and postoperative neurological deficits in MRgLITT. To optimize outcomes, further prospective studies are required to establish long-term data and prognoses for treatment of epilepsy using MRgLITT, especially among the pediatric population.