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. 2021 Sep;62(9):2048-2059.
doi: 10.1111/epi.16989. Epub 2021 Jul 17.

Changes in epileptogenicity biomarkers after stereotactic thermocoagulation

Margherita Contento  1 , Francesca Pizzo  2   3 , Víctor J López-Madrona  2 , Stanislas Lagarde  2   3 , Julia Makhalova  3   4 , Agnes Trébuchon  2   3 , Samuel Medina Villalon  2   3 , Bernard Giusiano  2   3 , Didier Scavarda  5 , Romain Carron  6 , Nicolas Roehri  2 , Christian-George Bénar  2 , Fabrice Bartolomei  2   3
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Free article

Changes in epileptogenicity biomarkers after stereotactic thermocoagulation

Margherita Contento et al. Epilepsia. 2021 Sep.
Free article

Abstract

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.

Keywords: epileptogenic biomarkers; stereo-electroencephalography; thermocoagulation.

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References

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