Authors :
Presenting Author: Alejandra Vasquez, MD – Mayo Clinic Rochester
Karimul Islam, M.B.B.S – Department of Neurology – Mayo Clinic Rochester; Madeline Cross, M.D. – Department of Neurology – Mayo Clinic Rochester; kai Miller, M.D.,Ph.D. – Department of Neurological Surgery – Mayo Clinic Rochester; Jamie Van Gompel, M.D. – Department of Neurological Surgery – Mayo Clinic Rochester; Anthony Fine, M.D. – Department of Neurology – Mayo Clinic Rochester; Brian Lundstrom, M.D.,Ph.D. – Department of Neurology – Mayo Clinic Rochester
Rationale:
Stereo encephalography-guided radiofrequency thermo-coagulation (SEEG-guided RF-TC) is a stereotactic lesioning procedure that targets disruption of epileptogenic networks through the recording electrodes. Despite its increased use as a diagnostic approach for drug-resistant focal epilepsies (DREs), data on clinical outcomes is limited. We aimed to describe the seizure outcomes following RF-TC before and after definitive intervention, including open surgical resection, laser ablation, and neuromodulation. Methods:
A retrospective study was conducted in patients who underwent RF-TC through December 2022. RF-TC was performed through implanted sEEG leads at the following: sites confirmed to be non-eloquent through stimulation mapping, seizure onset zone (SOZ) subset sites when SOZ overlapped with eloquent cortex, or when in multifocal SOZ, RF-TC and subsequent therapy was anticipated to be palliative. We assessed Engel Classification after RF-TC and definitive intervention. Results:
We evaluated 25 patients (11 females) with a diagnosis of DRE and a median age of 18.9 years (range 5-56). Epilepsy etiologies were structural (56%) and unknown (44%). Brain MRI showed focal cortical dysplasia (21%), postsurgical (21%) and poststroke (14%) encephalomalacia, hippocampal sclerosis (7%), tuberous sclerosis (7%), postinfectious sequelae (7%), and others (21%). The most common seizure semiology was focal motor with impaired awareness (37%).
The median time from epilepsy onset to RF-TC was 5.4 years (range 2-35). Patients were monitored using sEEG for a total median time of 8 days (4-26). The mean number of coagulation sites was 8.9 (1-22). Locations involved temporal (56%), frontotemporal (24%), frontal (12%), frontoparietal (4%), and temporoparietal (4%) head regions. SEEG leads were explanted in 48% of patients immediately following RF-TC, while 52% of patients remained on cEEG for a median of 24 hours (0.6-66).
The median overall follow-up time after RF-TC was 7.2 months. After a median time of 4.4 months (1-23), 17 (68%) patients underwent definitive surgery (laser ablation 53%, open surgical resection 47%). After a median time of 6.9 months (6-8), three (12%) patients had RNS placement. Five patients (20%) had no definitive treatment.
Prior to any definitive treatment (median follow-up 3.5 months after RF-TC), 48% showed at least worthwhile improvement (12% Engel class I, 16% class II, 20% class III) and 52% of patients showed no improvement. Following definitive treatment, 17 (68%) patients had complete follow-up (median time of 2.7 months). From eight patients who had previously shown at least worthwhile improvement, 87.5% had Engel class I and 12.5% had class III. From nine patients with no prior improvement, 33% had Engel class I, 22% class II and III, and 44% class IV. No surgical complications were reported.
Conclusions:
sEEG-guided RF-TC was safe and showed improvement in seizure outcomes prior to surgical procedure or neuromodulation. RF-TC is a potentially beneficial diagnostic approach prior to definitive surgical intervention in patients with DRE. Funding: None