Effects of laser interstitial thermal therapy for mesial temporal lobe epilepsy on the structural connectome and its relationship to seizure freedom

Abstract

Objective: Laser interstitial thermal therapy (LITT) is a minimally invasive surgery for mesial temporal lobe epilepsy (mTLE), but the effects of individual patient anatomy and location of ablation volumes affect seizure outcomes. The purpose of this study is to see if features of individual patient structural connectomes predict surgical outcomes after LITT for mTLE.Methods: This is a retrospective analysis of seizure outcomes of LITT for mTLE in 24 patients. We use preoperative diffusion tensor imaging (DTI) to simulate changes in structural connectivity after laser ablation. A two-step machinelearning algorithm is applied to predict seizure outcomes from the change in connectomic features after surgery.Results: Although node-based network features such as clustering coefficient and betweenness centrality have some predictive value, changes in connection strength between mesial temporal regions predict seizure outcomes significantly better. Changes in connection strength between the entorhinal cortex (EC), and the insula, hippocampus, and amygdala, as well as between the temporal pole and hippocampus, predict Engel Class I outcomes with an accuracy of 88%. Analysis of the ablation location, as well as simulated, alternative ablations, reveals that a more medial, anterior, and inferior ablation volume is associated with a greater effect on these connections, and potentially on seizure outcomes.Significance: Our results indicate (1) that seizure outcomes can be retrospectively predicted with excellent accuracy using changes in structural connectivity, and (2) that favorable connectomic changes are associated with an ablation volume involving relatively mesial, anterior, and inferior locations. These results may provide a framework whereby individual pre-operative structural connectomes can be used to optimize ablation volumes and improve outcomes in LITT for mTLE.

White matter network organization predicts memory decline after epilepsy surgery

“…In fact, we a-priori selected these MTL nodes, as these are epileptogenic in mesial TLE, directly affected by surgical resection 28 or ablation, and linked to episodic memory 47 . Our findings of higher predictive value of local than global metrics is in line with post-operative seizure outcome studies in which abnormalities in network connectivity of MTL regions specifically produced improved prediction of seizure freedom 23,48 .…”

Temporal lobe epilepsy surgery: Piriform cortex resection impacts seizure control in the long‐term

“…With regard to extended PiC resection to significantly improve favorable seizure outcome, the current study supports the hypothesis that the PiC may profoundly be involved in genesis and propagation of seizures in the temporal lobe. Since the minimally invasive procedures such as LITT are increasingly gaining interest, the access to the novel ablative target volumes in the mesial temporal lobe is becoming an area of focus 7,8,19 . In the recently published study, Liu et al.…”

The Temporal Lobe Club: Newer Approaches to Treat Temporal Lobe Epilepsy

“…31 However, a greater reduction of structural connectivity between key EZN and PZN network nodes was associated with seizure freedom. 32 When the patient is not a surgical candidate, palliative strategies such as thermocoagulation or neurostimulation are available. Thermocoagulation destroys the epileptogenic nodes and can be the method of choice in some etiologies, such as periventricular nodular heterotopia or hypothalamic hamartoma.…”