Radiofrequency Thermocoagulation Lesion Characteristics Using the Cross-Bonding Stereoelectroencephalography...

Stereoelectroencephalography (sEEG) is a commonly used invasive method of mapping the epileptogenic zone (EZ) in patients with drug-resistant epilepsy. Generating radiofrequency thermocoagulation (RF-TC) lesions during sEEG coverage, by connecting a radiofrequency generator to a single electrode, has recently emerged as an adjunct to resective surgery. However, single-electrode RF-TC has not been effective in maintaining long-term seizure control, largely due to the small heat lesion size it can produce, and, therefore, has limited use. The "cross-bonding" technique has recently been reported, where bipolar lesioning is performed between two different and separated electrodes, in an attempt to ablate larger areas of the EZ. The purpose of this study was to analyse cross-bonding lesion characteristics using the DIXI medical electrodes and DIXI interface system and determine optimal RF-TC parameters for safe and effective clinical practice.

A chicken albumin in vitro model was created with DIXI sEEG electrodes, DIXI interface system, and a Cosman radiofrequency generator. RF power and interelectrode distance was altered and lesion size, time and confluence were recorded and analysed.

Confluent lesions were reliably produced at interelectrode distances of up to 7 mm. The largest lesions were produced at a RF power of 4-5 W, where increases in power greater than this paradoxically produced smaller lesions. Maximal lesion dimensions for height, width, and depth of lesions were identified. Lesion expansion routinely continued beyond 180 s of current delivery, with averages close to 400 s for the largest lesions generated.

Our in vitro modelling of the cross-bonding technique supports the use of the DIXI sEEG electrodes for generating thermal lesions in a safe, effective, and reproducible manner.