Authors :
Presenting Author: Vincent Joris, MD – Institute of Neurosciences, UCLouvain
Laurence Dricot, MD, PhD – Institute of Neurosciences, UCLouvain
Roberto Santalucia, MD – Institute of Neurosciences, UCLouvain, Brussels, Belgium
Alexane Fierain, MD – Cliniques Universitaires Saint Luc
Susana Ferrao-Santos, MD, PhD – Cliniques Universitaires Saint Luc
Patrice Finet, MD – Cliniques Universitaires Saint Luc
Loïc de nijs, MD – Cliniques Universitaires Saint Luc
Ron Kupers, MD, PhD – Institute of Neuroscience, UCLouvain
Riëm El Tahry, MD, PhD – Institute of Neurosciences, UCLouvain, Brussels, Belgium
Rationale:
Stereoencephalography (SEEG)-guided radiofrequency thermocoagulation (RFTC) is often used to better characterize the epileptic network and to estimate the potential outcome of subsequent resection or disconnection surgery in drug-resistant epilepsy. However, the impact of RFTC on connectivity changes has rarely been investigated [1].Methods:
We prospectively included SEEG patients who underwent RFTC at our institution. All patients underwent resting-state functional MRI (rs-fMRI) at baseline (prior to SEEG) and again 3–6 months after RFTC. Patients were classified as responders (R, >40% seizure reduction) or non-responders (NR, < 40% seizure reduction) based on seizure frequency at follow-up. Connectivity matrices were computed from both rs-fMRI sessions using an augmented Brainnetome atlas [2] (246 original regions plus 40 cerebellar regions). Electrode contact locations were identified on post-implantation MRI using Brainstorm [3]. Each region was labeled as thermocoagulated or not (TC vs NTC), part of the ictal network or not (I vs NI), and part of the interictal network or not (IC vs NIC), based on SEEG recordings. We analyzed connectivity changes between timepoints, distinguishing positive (increase) from negative (decrease) connectivity changes.
Results:
Seven patients (5M/2F, mean age 23.7y, range 10–42y) were included. RFTC was done in 12 contacts/patient in mean (range 4-21). At follow-up, 4 patients were classified as responders and 3 as non-responders. Both TC and NTC regions exhibited connectivity changes, but no statistical difference was observed between them. However, responders showed significantly larger changes than non-responders, both positive (+0,069 vs +0,045, p < 0.001) and negative (−0,071 vs −0,054, p < 0.001). The strongest correlation with responder status was observed for positive connectivity changes in both ictal regions (R² = 0.362) and interictal regions (R² = 0.347).Conclusions:
Rs-fMRI may be a valuable tool for monitoring connectivity changes following epilepsy treatment. Responders exhibited significantly greater connectivity modifications compared to non-responders. A good response to RFTC was most strongly associated with increased connectivity in ictal and interictal regions.
Funding: VJ is funded by the FNRS (National Fund for Research) for his research work.
Data acquisition was funded by the WELBIO (Walloon Excellence in Life Sciences and Biotechnology)