Stereoelectroencephalography-guided radiofrequency thermocoagulation in drug-resistant focal epilepsy

Abstract

Background: Stereoelectroencephalography (SEEG) has become a common diagnostic method in epilepsy surgery and is found to be safe for a wide range of clinical applications. SEEG combined with radiofrequency thermocoagulation (RF-TC) not only reveals the seizure onset zone by hypothesis, but also acts as a treatment option without any additional cost to institutions and patients. Thus, we analyzed the treatment of the SEEG-guided RF-TC.

Methods: This retrospective study analyzed seventeen epileptic patients treated with RF-TC between April 2019 and December 2020. All patients underwent a single round of SEEG-guided RF-TC treatment after more than three habitual seizures were recorded. The demographic characteristics of the patients were retrospectively reviewed. Outcomes were assessed using the Engel classification system.

Results: All patients underwent SEEG-guided RF-TC without catastrophic functional damage. Follow-up data of all patients were complete. The number of contacts per patients where RF-TC was applied ranged from 9 to 43 (mean: 17.7±10.2). After RF-TC, the types of anti-epileptic drugs used reduced from 2.4±0.7 to 1.6±0.7. With RF-TC alone, four (23.5%) patients achieved Engel Ia, two (11.8%) patients achieved Engel Ib, one patient underwent resection without seizure at the 5-month follow-up, five patients had a relapse after 3-10 months of seizure freedom, and five patients had recurrence after 1 month. After RF-TC, six patients underwent secondary interventions followed by resection. Overall, 12 patients achieved Engel Ia or Ib, three patients achieved Engel IIa or IIb, and two patients achieved Engel IIIa. There were no Engel IV cases.

Conclusions: SEEG-guided RF-TC performed in our institution was found to be a safe ablation procedure for the treatment of drug-resistant focal epilepsy. All patients experienced a reduction in the frequency of seizures after receiving RF-TC. RF-TC can be used as a palliative treatment option for patients with epilepsy who refuse surgery or cannot undergo resection surgery. Recurrence of focal epilepsy after RF-TC can be treated with resection surgery to achieve the seizure-free status.

Keywords: Stereoelectroencephalography (SEEG); drug-resistant epilepsy; focal epilepsy; radiofrequency thermocoagulation (RF-TC).

Figure 1

Example of RF-TC in a drug-refractory epilepsy case. (A) Representative case of drug-refractory epilepsy treated with RF-TC (No. 3). MR image before stereoelectroencephalography; (B) the onset of seizure captured by stereoelectroencephalography (Sup. Temp. Gyrus: superior temporal gyrus; Mid. Temp. Gyrus: middle temporal gyrus; Hippo.: hippocampus); (C) MR image obtained within 48 hours after RF-TC. RF-TC, radiofrequency thermocoagulation.