Name:
10.3171/2024.4.FOCVID2422
Description:
10.3171/2024.4.FOCVID2422
Thumbnail URL:
https://cadmoremediastorage.blob.core.windows.net/d3782c42-a3b3-46b9-a876-0284e718d5af/videoscrubberimages/Scrubber_307.jpg
Duration:
T00H10M23S
Embed URL:
https://stream.cadmore.media/player/d3782c42-a3b3-46b9-a876-0284e718d5af
Content URL:
https://cadmoreoriginalmedia.blob.core.windows.net/d3782c42-a3b3-46b9-a876-0284e718d5af/10. 24-22.mp4?sv=2019-02-02&sr=c&sig=5Dsw%2BsgtXiMIgwygRFspJE6ZWymnBimnfQJwEcryitc%3D&st=2026-05-13T19%3A06%3A30Z&se=2026-05-13T21%3A11%3A30Z&sp=r
Upload Date:
2024-05-30T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
[MUSIC PLAYING]
SPEAKER 1: Our patient is a 21-year-old right-handed woman with intractable focal epilepsy. Seizure onset occurred at 9 years of age. Primary seizure semiology is characterized by left head turn and hypermotor bicycling movements occurring 20 times monthly, often arising from sleep. Rarely seizures can progress to generalized tonic-clonic seizure activity. MRI revealed a left superior frontal sulcation anomaly. PET was notable for subtle hypometabolism in the left frontal and cingulate region, and MEG demonstrated a cluster of dipoles in the left frontal head region. Video EEG monitoring recorded six left frontal central onset seizures arising from sleep. Further monitoring was completed with stereo-EEG targeting the hypothesized seizure onset region. Seizure onset was recorded from the LE and LN and LM contacts in the primary motor and premotor SMA region.
SPEAKER 1: Frequent interictal epileptiform activity was recorded from LE and LN contacts. Here is a seizure seen arising from LE and LN contacts. sEEG cortical stimulation mapping was notable for eloquent cortex co-localizing with the seizure onset zone. Stimulation of LE, LN, and LM contacts resulted in right hand and face motor activation.
SPEAKER 1: Given colocalization of seizure onset zone and eloquent cortex, a trial of therapeutic stimulation was delivered through stereo-EEG hardware. Here, we show the device used to deliver stimulation through the sEEG contacts. From left to right, we see a clinician programmer, a clinical telemetry module, and the external neurostimulator. The ENS outputs to a custom cable terminating in 16 contacts that are connected to sEEG hardware via stackable touch-proof jumper cables.
SPEAKER 1: During therapeutic stimulation, there was a suppression of interictal discharges. Note a reduction in interictal discharges between the 2-Hz stimulation artifact following discontinuation of stimulation on the left side of the EEG tracing. We can see a transient suppression of interictal discharges.
SPEAKER 2: So in this approach, a diffuse seizure onset zone involving multiple eloquent locations and successful prestimulation during SEEG predicted a good outcome with multiple therapies. However, CSCS (chronic or ongoing subthreshold cortical stimulation) was recommended to the patient. We believe this was predicted by the EEG monitoring. The benefits of decreased seizure frequency, preserved neurologic function, and generally reversible if unsuccessful, were utilized in this particular situation.
SPEAKER 2: Although all the listed therapies here are options, chronic subthreshold cortical stimulation was felt to be in the patient's best interest due to the eloquent onset area. Here, the patient is placed in a Leksell frame and coregistered with stealth stereotaxis. We identify our entry points and align these under subgaleal entry points. We then, in the locations where we're targeting our cortical sites, we affix dog bones to accept our electrodes.
SPEAKER 2: We then align the precision aiming device. A cannula is then placed just like we do sEEG. We drill through the skull, and then a customized lead delivery device is screwed into the cannula that allows typical targeting cannula with inner diameters of 1.4 mm to be placed to increase the accuracy of the patient's implant. Once this is done, the inner stylet is removed. We then measure from the back of this cannula.
SPEAKER 2: We also measure at the skull to identify the depth of the lead. The lead is then placed into the cortex. We then identify on fluoroscopy the exact location. The lead is then held at the skull, the cannula withdrawn, and it is secured with our dog bone, and then the excess wire is tied down to have galea coverage over our openings. Once all of our electrodes have been placed, we then tag these with either a series of ties in order to identify our implants when hooking this up to the battery.
SPEAKER 2: This was then copiously irrigated and, of course, closed in multiple layers. We then go to the subclavicular region on that side, make a small incision, plan two fingerbreadths below the clavicle. We then open and make a subfascial battery pocket. We then tunnel down from the superior cranial incision twice with two separate passers in order to allow electrodes to be passed up from the inferior incision to the superior incision.
SPEAKER 2: In this particular circumstance, four electrodes are assembled to a singular Intellis battery. The Intellis battery is a pain battery that would allow the stimulation of all 16 electrodes, if possible, or multiple or more complex stimulation parameters. In this circumstance, the DBS intracranial leads have to be assembled to spine lead extensions, which have very tight occlusions. You have to be very careful when passing into these areas in order not to break the electrodes.
SPEAKER 2: Once this is done, as typical, the booty is passed over and then secured with suture. We then, of course, check interoperative impedances in order to determine if the assembly is working correctly. And we again make sure that our electrode assembly is correct. These are then copiously irrigated, and the wounds are closed in multiple layers in order to, again, prevent infection.
SPEAKER 2:
SPEAKER 3: Neurostimulation for medically intractable epilepsy typically consists of either duty cycle or responsive stimulation paradigms. However, a seizure-free outcome is rarely observed with either of those mechanisms or approaches. Chronic subthreshold cortical stimulation, or what we call CSCS, aims to suppress interictal cortical epileptiform discharges by using continuous electrical stimulation. Unlike RNS, CSCS does not require the use of seizure detection algorithms which sometimes lack specificity.
SPEAKER 3: Also, CSCS provides a continuous stimulation, which is advantageous over the duty cycle stimulation paradigms where stimulation is often off for the majority of the time. Additionally, CSCS lends a possibility of corticothalamic implants, as demonstrated with the patient compared to RNS. A trial stimulation is often required before implementation of a CSCS system using temporarily implanted hardware such as depth electrodes.
SPEAKER 3: In summary, CSCS is a safe and effective alternative treatment for drug resistant epilepsy, especially those involving eloquent cortex, and has demonstrated safety and efficacy.
SPEAKER 4: Although the literature is relatively sparse regarding investigations of CSCS for drug-resistant epilepsy, there are a few studies demonstrating a safety and efficacy. One study is a single-center retrospective review that compared five different neuromodulation strategies for treatment of drug-resistant epilepsy. These neuromodulation strategies included anterior thalamic, DBS, centromedian, thalamic, DBS, PNS, CSCS, and VNS. The study included 159 patients.
SPEAKER 4: Overall, there was a 61% seizure reduction in 60% responder rate across all neuromodulation modalities. Notably, in an unadjusted pairwise comparison, the total median seizure reduction was most improved for CSCS when compared to the other neuromodulation modalities. Additionally, cortical stimulation, which includes both RNS and CSCS, was associated with an improved total median seizure reduction when compared to subcortical stimulation, which encompasses anterior thalamic DBS, centromedian, thalamic nuclei, DBS and VNS, at 67% versus 52% respectively.
SPEAKER 4: Another study investigating the safety and efficacy of CSCS is a case series of 10 adult patients with drug-resistant epilepsy due to various pathologies who underwent CSCS treatment. All patients experienced an uneventful postoperative course and experienced an improvement in both seizure severity and frequency. In terms of the current state of CSCS availability, there are devices, as in this particular paper, that can be used to perform CSCS such as the Medtronic or Boston Scientific devices.
SPEAKER 1: The permanent electrodes are seen in yellow, and they are coregistered to the SEEG implant with seizure onset zone electrodes marked in red. For the permanent implant, one lead targeted the anterior nucleus of the thalamus, while three leads targeted the cortical seizure onset region. The patient has had five clinical seizures over 11 months following device placement at greater than 90% seizure reduction.
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