Changes in epileptogenicity biomarkers after stereotactic thermocoagulation

Margherita Contento (1) , Francesca Pizzo (2, 3) , Víctor López‐madrona (3) , Stanislas Lagarde (2, 3) , Julia Makhalova (2, 4, 5) , Agnes Trébuchon (2, 3) , Samuel Medina Villalon (2, 3) , Bernard Giusiano (3, 6) , Didier Scavarda (7, 3) , Romain Carron (8, 3) , Nicolas Roehri (3) , Christian‐george Bénar (3) , Fabrice Bartolomei (2, 3)

1 UniFI - Università degli Studi di Firenze = University of Florence = Université de Florence
2 Service d'Epileptologie et de Rythmologie Cérébrale [Hôpital de la Timone, AP-HM]
3 INS - Institut de Neurosciences des Systèmes
4 CRMBM - Centre de résonance magnétique biologique et médicale
5 CEMEREM - Centre d'Exploration Métabolique par Résonance Magnétique [Hôpital de la Timone - APHM]
6 APHM - Assistance Publique - Hôpitaux de Marseille
7 Service de pédiatrie spécialisée et médecine infantile (neurologie, pneumologie, maladies héréditaires du métabolisme) [Hôpital de la Timone - APHM]
8 TIMONE - Hôpital de la Timone [CHU - APHM]

Objective Stereo-electroencephalography (SEEG)-guided radiofrequency thermocoagulation (RF-TC) aims at modifying epileptogenic networks to reduce seizure frequency. High-frequency oscillations (HFOs), spikes, and cross-rate are quantifiable epileptogenic biomarkers. In this study, we sought to evaluate, using SEEG signals recorded before and after thermocoagulation, whether a variation in these markers is related to the therapeutic effect of this procedure and to the outcome of surgery. Methods Interictal segments of SEEG signals were analyzed in 38 patients during presurgical evaluation. We used an automatized method to quantify the rate of spikes, rate of HFOs, and cross-rate (a measure combining spikes and HFOs) before and after thermocoagulation. We analyzed the differences both at an individual level with a surrogate approach and at a group level with analysis of variance. We then evaluated the correlation between these variations and the clinical response to RF-TC and to subsequent resective surgery. Results After thermocoagulation, 19 patients showed a clinical improvement. At the individual level, clinically improved patients more frequently had a reduction in spikes and cross-rate in the epileptogenic zone than patients without clinical improvement (p = .002, p = .02). At a group level, there was a greater decrease of HFOs in epileptogenic and thermocoagulated zones in patients with clinical improvement (p < .05) compared to those with no clinical benefit. Eventually, a significant decrease of all the markers after RF-TC was found in patients with a favorable outcome of resective surgery (spikes, p = .026; HFOs, p = .03; cross-rate, p = .03). Significance Quantified changes in the rate of spikes, rate of HFOs, and cross-rate can be observed after thermocoagulation, and the reduction of these markers correlates with a favorable clinical outcome after RF-TC and with successful resective surgery. This may suggest that interictal biomarker modifications after RF-TC can be clinically used to predict the effectiveness of the thermocoagulation procedure and the outcome of resective surgery.

Domaines: Chirurgie

Margherita Contento, Francesca Pizzo, Víctor López‐madrona, Stanislas Lagarde, Julia Makhalova, et al.. Changes in epileptogenicity biomarkers after stereotactic thermocoagulation. Epilepsia, 2021, 62 (9), pp.2048-2059. ⟨10.1111/epi.16989⟩. ⟨hal-03537406⟩