Name:
10.3171/2024.4.FOCVID2442
Description:
10.3171/2024.4.FOCVID2442
Thumbnail URL:
https://cadmoremediastorage.blob.core.windows.net/401507bc-df33-479f-afc6-0c5036c2f608/videoscrubberimages/Scrubber_89.jpg
Duration:
T00H06M17S
Embed URL:
https://stream.cadmore.media/player/401507bc-df33-479f-afc6-0c5036c2f608
Content URL:
https://cadmoreoriginalmedia.blob.core.windows.net/401507bc-df33-479f-afc6-0c5036c2f608/14. 24-42.mp4?sv=2019-02-02&sr=c&sig=vWTXjGBkgSVzezkR7VbNrbO0aupl7LTD9wUdysnMm6E%3D&st=2026-04-28T04%3A49%3A16Z&se=2026-04-28T06%3A54%3A16Z&sp=r
Upload Date:
2024-06-05T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
[MUSIC PLAYING]
SPEAKER: SEEG-guided radiofrequency-thermocoagulation as known as RFTC, is a lesional stereotactic technique, consisting in creating radiofrequency lesions within epileptic networks via previously implanted SEEG electrodes. Its target is selected based on the SEEG recording. This technique is performed at the end of a video-SEEG. During SEEG-guided RFTC, a radiofrequency current is delivered in adjacent contacts of an electrode, thus creating thermal lesions around the electrode.
SPEAKER: Several lesions can be obtained by coagulating multiple pairs of adjacent contacts. so as to obtain a confluent lesion as shown here in vitro on albumin.
SPEAKER: There are three main indications of SEEG-guided RFTC. First, this procedure can be curative by destruction of the entire ictal onset zone. This is of particular interest in cases of deep and small- volume ictal onset zones, as they are difficult to access surgically and need to be identified by SEEG. Periventricular nodular heterotopia is a perfect example, as only a small portion of the heterotopia is generally involved in the seizures, thus requiring an intracranial recording to be identified, and as they are typically deeply located lesions.
SPEAKER: Secondly, SEEG-guided RFTC can be a diagnostic procedure for complex epileptic network. The volume of the RFTC is unlikely to cure the patient, but can have a great diagnostic value. Indeed, any improvement, even transient in frequency or intensity of the seizures has an excellent predictive positive value of surgical success, 93%. It is even possible to perform calculations while the SEEG procedure is still in progress and to carry on recording to test an electrophysiological hypothesis.
SPEAKER: Finally, there is a palliative indication in the case of wide epileptic networks where multiple lesions can be performed in order to obtain better epileptic control. In such cases, repeated procedures are often necessary to maintain the effect over time. You can see here the first surgical step. It consists in the implementation of SEEG electrodes on which coagulation is possible.
SPEAKER: Following a robot-guided avascular trajectory of implantation, the bone is drilled and the dura coagulated before the insertion of the screw-in base, which the size is adapted to the thickness of bone and the temporalis muscle. We then prepare the electrode path via insertion of a stylus whose length is 5 mm shorter by the exploration length of the electrode. We then introduce smoothly the electrode.
SPEAKER: It is to be noted that it is not recommended to shave the patient's head before an SEEG procedure, the example presented being a patient for whom this is a usual haircut. At the end of the procedure, adequate position of the electrodes has to be controlled by a CT scan. We recommend realization of a brain MRI to better evaluate the anatomical position of the electrodes, as well as their relationships with adjacent vessels in order to select potential targets for radiofrequency thermocoagulation.
SPEAKER: We can see the early appearance of a low-amplitude fast pattern at the level of the epileptic seizure, considered as either the epileptic focus or primordial irritative zone that is difficult to access surgically. One or several contacts are selected as candidate for thermocoagulation after carefully verifying and imaging the absence of vessels in the immediate neighborhood.
SPEAKER: The patient is awake in the operating room with permanent clinical monitoring by a neurologist. The electrode chosen to undergo coagulation is connected to the monitor. The radiofrequency thermocoagulation is then performed in the continuous clinical evaluation, as our patient can be seen here performing motor and speech tasks under evaluation of the clinician. The increase of energy, which is directly correlated to the power and the voltage delivered, is realized with a maximum time of coagulation.
SPEAKER: It is necessary to check the impedance throughout the whole process. As SEEG electrodes do not have a thermocouple, it is indeed not possible to directly monitor temperature. This bipolar thermocoagulation are first monitored through impedance. And abrupt change of impedance means that the coagulation has occurred. Most coagulation will stop automatically in such a case of impedance brutal modification.
SPEAKER: It is common for patients to perceive a noise, similar to a water drop falling on a hot pan, during the coagulation process. Even when the sound is heard, it is appropriate to carry on the coagulation, as lesion volume can increase past that point. Following the thermocoagulation, electrodes are explanted. When necessary, this explantation can be delayed in order to record the consequences of the coagulation.
SPEAKER: A postprocedure imaging is finally systematically done after coagulation. Outcome and efficacy depend on the indication of SEEG-guided RFTC. Current literature depicts periventricular nodular heterotopias as the best indications in term of results, with 81% responders at 1 year and as high as 76% of seizure-free patients.
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