Diffusion spectrum imaging based semi-automatic optic radiation tractography for vision preservation in SEEG-guided radiofrequency thermocoagulation

Change in Structural Connectivity Following Stereotactic Thermocoagulation in Mesial Temporal Lobe Epilepsy Patients

AIMS

To examine the association between postoperative lesions in distinct ROIs of the brain and the impact that their ablation would have on the structural and functional brain connectivity relative to outcomes.

METHODS

We retrospectively reviewed 21 patients with refractory unilateral MTLE. The percentage of each ablated gray matter region of interest (ROIs) was calculated, using a voxel-by-voxel comparison. The percentage of the affected fibers was calculated by assessing the neuronal change reflected by a decrease in anisotropy in the repeat scans (i.e., pre and postoperative). Graph theory analysis was used to investigate the change in the pre and postoperative structural and functional networks between the seizure-free and non-seizure-free groups.

RESULTS

Fifteen patients (71.42%) were seizure-free and six (28.57%) were non-seizure-free at a 12 to 48 months (23.80 ± 8.93) follow-up. Four patients (19.04%) reported memory decline following RFTC. The seizure-free group showed a larger ablation volume of both the amygdala (p = 0.024) and rhinal cortex (p = 0.035), and an alteration in structural connectivity networks metrics (p < 0.05) compared to the non-seizure-free group.

CONCLUSIONS

Our study shows that a higher ablation of both the amygdala and rhinal cortex led to improved structural connectivity and was associated with better outcomes. Our results provide insight into some essential elements of brain connectivity networks in MTLE and might contribute to the generation of novel evidence that could improve SEEG-guided RFTC interventions in MTLE patients.

Stereoelectroencephalography-Guided Radiofrequency Thermocoagulation: Diagnostic and Therapeutic Implications

Despite recent medical therapeutic advances, approximately one third of patients do not attain seizure freedom with medications. This drug-resistant epilepsy population suffers from heightened morbidity and mortality. In appropriate patients, resective epilepsy surgery is far superior to continued medical therapy. Despite this efficacy, there remain drawbacks to traditional epilepsy surgery, such as the morbidity of open neurosurgical procedures as well as neuropsychological adverse effects. SEEG-guided Radiofrequency Thermocoagulation (SgRFTC) is a minimally invasive, electrophysiology-guided intervention with both diagnostic and therapeutic implications for drug-resistant epilepsy that offers a convenient adjunct or alternative to ablative and resective approaches. We review the international experience with this procedure, including methodologies, diagnostic benefit, therapeutic benefit, and safety considerations. We propose a framework in which SgRFTC may be incorporated into intracranial EEG evaluations alongside passive recording. Lastly, we discuss the potential role of SgRFTC in both delineating and reorganizing epilepsy networks.