Stereotactic Radiofrequency Thermocoagulation (L-RFTC) of Focal Cortical Dysplasias: Applicable to Children?

Background/Purpose: High-resolution magnetic resonance imaging (MRI) increasingly reveals small bottom-of-sulcus focal cortical dysplasias type IIB (BOS-FCD). In adult pharmacoresistant epilepsy patients these intrinsically epileptogenic lesions can be subject to resective epilepsy surgery and stereotactic lesion-focused radiofrequency-thermocoagulation (L-RFTC). This presentation asks if L-RFTC of BOS-FCD could already be applied in childhood.

Methods: Seven adult patients with childhood onset epilepsy (age at onset 1–18 years (y), mean 6.1 years; age at surgery 29–56, mean 40.1 years; duration of epilepsy 23–55, mean 34 years) received L-RFTC of BOS-FCD. All had previous noninvasive presurgical workup, and three had additional invasive workup. Invasive EEG and intraoperative EEG from the tip of the coagulation device showed epileptic discharges in and outside the lesions (perilesional epileptic discharges, PLD) in all patients.

Results: L-RFTC was planned based on MRI. However, in six of the seven patients detection of PLD led to extension of the coagulation up to 4.8 mm beyond lesion limits. Nevertheless, in all patients some PLD sites remained uncoagulated. Under continued anticonvulsive medication, four of the seven patients became completely seizure free (outcome Engel 1a), two achieved an Engel 1b outcome, one patient following incomplete lesion coagulation Engel 3.

Conclusion: In adult patients, minimal invasive L-RFTC of BOS-FCD can lead to seizure freedom. It should be assessed if the technique is applicable to children, too. This could prevent unnecessary long courses of epilepsy. Prerequisite for L-RTFC in children are: early identification of BOS-FCD IIB (performing the right MRI protocol at the right time), good lesion delineation from surrounding tissue (new MRI sequences may prove helpful) and clarification to what degree PLD can be ignored.