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 » Case Study
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Table of Contents    
VIDEO SECTION-OPERATIVE NUANCES: STEP BY STEP
Year : 2021  |  Volume : 69  |  Issue : 3  |  Page : 587-591

Robotic-Guided Stereoelectroencephalography for Refractory Epilepsy: Technique and Nuances


1 Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
2 Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
3 Department of Neurosurgery, Airlangga University/Dr Soetomo General Hospital, Surabaya, Indonesia

Date of Submission02-Jun-2021
Date of Decision02-Jun-2021
Date of Acceptance02-Jun-2021
Date of Web Publication24-Jun-2021

Correspondence Address:
Prof. Poodipedi S Chandra
Professor of Neurosurgery, PI and Team Leader COE and MEG Centre, Core Faculty Epilepsy and Functional Neurosurgery Division, All India Institute of Medical Sciences, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.319246

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 » Abstract 


Background: Stereoelectroencephalography (SEEG) has become an integral part of epilepsy surgery, often used in the localization of the epileptogenic zone. It is an essential modality not only in the evaluation of nonlesional but also lesional drug refractory epilepsy, especially in the presence of anatomo-electro-clinical discordance.
Objective: To describe our technique and the operative nuances involved in the performance of robotic SEEG placement.
Methods: A 28-year lady with seizure onset at the age of 15 years presented with two types of seizures: one was associated with an aura of chest discomfort, palpitations along with oral and bilateral automatisms. There was associated speech and behavioral arrest along with ictal urinary incontinence. The other type has head turning to the right with secondary generalization lasting up to 1 min.
Results: Multimodality investigations showed bilateral temporal origin of seizures. SEEG evaluation revealed left amygdala and anterior temporal neocortical (ATL) origin of seizures. The patient underwent left ATL and amygdalectomy. Histopathology revealed focal cortical dysplasia (FCD type Ib). The patient became seizure free (ILAE Class 1) at 1-year follow up.
Conclusion: Robotic-guided SEEG is a safe and accurate method of evaluating complex MRI negative epilepsy.


Keywords: Amygdalectomy, epilepsy, MRI negative, robotic guidance, SEEG
Key Message: Robotic SEEG placement is a widely accepted and well documented technique globally. It is a safe and efficacious method of SEEG placement with comparable accuracy compared to the frame based technique.


How to cite this article:
Doddamani RS, Samala R, Subianto H, Ramanujam B, Tripathi M, Chandra PS. Robotic-Guided Stereoelectroencephalography for Refractory Epilepsy: Technique and Nuances. Neurol India 2021;69:587-91

How to cite this URL:
Doddamani RS, Samala R, Subianto H, Ramanujam B, Tripathi M, Chandra PS. Robotic-Guided Stereoelectroencephalography for Refractory Epilepsy: Technique and Nuances. Neurol India [serial online] 2021 [cited 2021 Jul 24];69:587-91. Available from: https://www.neurologyindia.com/text.asp?2021/69/3/587/319246




Localization of the epileptogenic zone is complex and not straightforward in a significant proportion of patients with refractory epilepsy. Invasive intracranial monitoring in the form of stereoelectroencephalography (SEEG) and subdural grids are used in the absence of concordance between the clinical, imaging, and the video electroencephalography (VEEG) data.[1] The other indication being magnetic resonance imaging (MRI) negative epilepsy, otherwise known as substrate negative/nonlesional epilepsy. Subdural grid better evaluates the convexity cortex for epileptogenicity, while SEEG is best for the hidden cortex in the depths of the sulcus as well as deep-seated structures.[1],[2]


 » Objective Top


To describe the technique and operative nuances of SEEG electrode placement using robotic guidance.


 » Case Study Top


A 28-year-old right-handed lady presented with seizure onset at the age of 15 years with a frequency of 2–3/day initially to 5–6/week with three appropriately dosed antiepileptics during the course of treatment. She had two types of seizures: one was associated with an aura of chest discomfort, palpitations along with oral and bilateral automatisms. There was associated speech and behavioral arrest along with ictal urinary incontinence. The second type had head turning to the right with secondary generalization lasting up to 1 min. The seizures were more during the day time. VEEG revealed bilateral seizure onsets; MRI brain was normal; and positron emission tomography (PET) and single-photon emission computerized tomography (SPECT) were suggestive of left anteromesial temporal and left posterobasal temporal focus, respectively. Magnetoencephalography (MEG) localized to bilateral temporal lobes (left >> right), while neuropsychology localizing to predominantly to the right temporal lobes. In view of lack of a clear hypothesis regarding localization, the patient was planned for SEEG placement.

Surgical procedure

The plan for placement of the SEEG electrodes is based on the final hypothesis formulated at the comprehensive epilepsy surgery meeting (CSEM), involving the epilepsy surgery team. At our institution, we routinely perform robotic-guided SEEG placement (ROSA, Zimmer Biomet, Warsaw, Indiana). The planning of the trajectories is made prior to the surgery on the robotic platform.

Imaging protocol

We follow a standardized MRI protocol for robotic surgeries at our institution:

  • T1WI, T2WI, fluid attenuated inversion recovery, T1WI MRI with double contrast acquired as volumetric 3D imaging
  • Square matrix
  • 1 mm slice thickness with no gaps.
  • Volumetric computerized tomography (CT) is acquired, which is merged with the MRI before registration and hence the CT is acquired in the same protocol as MRI to achieve perfect matching. This aids in superior registration and reduces the margin of error.


Surgical technique

The head is fixed with either a Mayfield clamp or a Leksell frame depending on the site and the number of SEEG electrodes to be placed. A Leksell frame is ergonomically better compared to a Mayfield clamp, as the operative space is completely unhindered for the movement of the robotic arm [Figure 1] and [Figure 2].
Figure 1: Equipment for SEEG implantation: 1. Ruler; 2. synthes hand gun; 3. drill bit 2.1 mm; 4. insulated monopolar probe; 5. depth guaze, 6. anchor bolt driver; and 7. anchor bolt

Click here to view
Figure 2: [a] Robot (ROSA Zimmer Biomet Warsaw, Indiana, USA) and O arm (Medtronic, USA) are positioned before beginning the surgery; [b] Alternatively Leksell frame G may be used for head fixation instead of Mayfield clamp, when multiple bilateral electrodes are planned, which provides more unhindered space for the movement of robotic arm, especially the temporal region. [c] Before drilling, the stopper is applied on the drill bit for a distance accounting for the thickness of the scalp and the bone (red flower bracket). [d] The distance to target (a) from the top of the robotic adaptor till the target point is noted from the robotic console. The length of the screw driver from the top of anchor bolt to the top of the robotic adaptor (b) is noted. [e] The length of the SEEG electrode to be inserted calculated by (a, b) and is measured on the ruler before insertion

Click here to view


>Video Link: https://youtu.be/Hoi3ByS9k7o

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Video timeline with audio transcript (Minutes)

0:00–0:15 – This video demonstrates the technique of robotic SEEG electrode implantation and our approach to MRI negative epilepsy

0:15–0:43 – A 28-year-young lady presented with a history of epilepsy for a duration of 13 years. She had two types of semiology: one was associated with an aura of chest discomfort and palpitations. There was a history of automatisms involving bilateral hands followed by speech arrest. The other type of semiology began with head turn to the right side followed by secondary generalization.

0:43–1:17 – VEEG revealed bilateral temporal seizure onset with right-sided predominance

1:19–1:38 – MRI brain revealed no focal lesions and was reported as normal

1:39–2:78 – PET and SPECT localized to left anterior and posterior basitemporal regions, respectively

2:07–2:18 – Neuropsychology assessment showed impaired visual memory more than the verbal suggestive of predominant right temporal involvement

2:21–2:48 – CSEM hypothesis bilateral temporal with clinical semiology, PET/SPECT, and MEG showing predominant right-sided localization, while VEEG and neuropsychology predominantly localized to the right temporal lobe.

2:49–3:09 – A total of 12 SEEG electrodes were planned in bilateral temporal to include the lateral and the mesial structures in addition to left basitemporal, bilateral cingulate, and insula in view of ictal urinary incontinence.

3:14–3:25 – The patient is positioned supine with the head fixed with a Mayfield clamp and attached to the robotic arm.

3:25–3:49 – Alternatively, Laksell frame B may use, which allows free space without hindering the robotic arm in cases of multiple bilateral implantations. There is scope to use three-point fixation for smooth registration, when laser forehead scanning is done.

3:50–4:43 – We routinely use six-point facial skin-based laser registration. This is followed by the mesh registration covering the nose and the forehead, followed by zig-zag laser scanning of the forehead and then manually scanning bilateral scanning of both the temple regions. Once the registration is complete the accuracy check is done for all the six facial points and to correct any errors more than 1 mm by matching these points manually. If the error of >1 mm persists, reregistration is performed.

4:44–5:00 – The robotic arm is driven to the desired trajectory and the entry point is marked as per the laser pointer.

5:01–5:49 – A twist drill craniostomy of 2.1 mm diameter is performed using a pneumatic-powered handheld drill. The robotic adaptor is closely applied to the scalp while drilling and a stopper is tightened at appropriate length accounting for the scalp and bone thickness. This is followed by dural coagulation using a monopolar coagulation.

5:52–7:13 – Anchor bolt is inserted and the distance to the target (A) and distance B (from the top of the adaptor to the top of the anchor bolt is calculated). This is followed by the calculation of the length of the electrode by negating B + 3 mm from A.

7:14–7:55 – Various types of electrodes are available in the market ranging from for simple recording purpose to multimodal functions (recording, stimulation, and lesioning) simultaneously. The desired electrode is inserted with cap fixation over the bolt after removing the stylet.

8: 00–13 – This is followed by O arm confirmation of the accuracy of electrode placement

8:15–8:42 – Accuracy check is performed after placing all the electrodes with a thin-slice postoperative CT brain

8:43–8:56 – The anterior, middle, and posterior basi-temporal along with the amygdalar contacts showed seizure activity; however, no such activity was seen on hippocampal contacts [Figure 3].
Figure 3: The final plan of SEEG electrode implantation. After implantation of all the electrodes as per the preoperative hypothesis, at least three to four spontaneous seizure activities were recorded. Stimulation was also be performed to induce habitual seizure and localize the suspected epileptogenic zone. In the figure, the anterior, middle, and posterobasal temporal as well as the amygdalar contacts (marked red) showed the seizure activity

Click here to view


9:02–9:32 – Hippocampal sparing lateral temporal neocortical and amygdala resection was planned. Preresection electrocorticography (ECOG) showed grade V discharges, which after anterior temporal resection reduced to grade-IV. Further resection of posterior and basitemporal region achieved a grade III ECOG. Finally, on resecting the amygdala grade II, readings were recorded, while recording with the strip electrode placed on the hippocampus did not reveal any activity. Hence, it was spared. Postoperative course was uneventful and CT brain showed a good resection cavity. Histopathology confirmed the diagnosis of focal cortical dysplasia Type Ib in both the neocortex and the amygdalar specimen. The patient remains to be seizure free at 1-year follow up.

Outcome

The postoperative course was uneventful and patient is seizure free (ILAE Class 1) at 1-year follow up. The resected specimen of temporal neocortex and amygdala revealed focal cortical dysplasia type-1b on histopathology.

Pearls and Pitfalls

  • Patient selection is critical for successful outcome. Comprehensive evaluation maximizing the noninvasive multimodality investigations and formulating a hypothesis is essential prior planning SEEG implantation.
  • Robotic registration should be performed meticulously in order to avoid gross errors in implantation, as the accuracy is completely dependent on the registration.
  • Using Leksell G frame as a head holder is superior to the routine Mayfield head clamp and should be used when multiple bilateral SEEG electrodes are planned under robotic guidance. The other advantage is using three postfixation in order to achieve unhindered forehead registration.
  • Both skin-based laser and bone fiducial-based registrations attain comparable accuracy.
  • Double-contrast T1WI MRI along with other sequences acquired in 3D is mandatory. Ensuring perfect merging of all the sequences before planning is of paramount importance.
  • The trajectories should be planned juxta-orthogonal (preferably within 30 degrees of the perpendicular axis) whenever feasible.
  • The cortical entry point planning of the trajectories should be precise, avoiding subdural veins and cortical vessels.
  • Optimal trajectory planning should be balanced between incorporating maximal gray matter simultaneously evading transgression of multiple sulci.
  • A 2.1 mm drill bit is preferable, so as to achieve firm fixation of the anchor bolt. The adapter mounted on the robotic arm should be in close contact with the scalp, to prevent the play of the drill bit.
  • Creating a track using a stiff metallic stylet through the anchor bolt prior inserting the electrodes ensures accurate placement.
  • CSF leak from the anchor bolt may occur despite capping. Injecting glue to seal off the leaking point may be considered.
  • Consider implanting multipurpose SEEG leads capable of performing recording, stimulation, and coagulation, into areas with focal lesions where local lesioning is contemplated.



 » Discussion Top


Intracranial EEG is a prerequisite in the evaluation of complex drug refractory epilepsy, not localized despite maximal multimodal evaluation.[1],[2] SEEG has gained universal acceptance over subdural grids in recent times, paralleling the advances in the field of stereotactic neurosurgery. Approximately, two thirds of the gray matter remain buried in the sulcal depths of the brain, which is otherwise inaccessible for recording with the conventional subdural grid. Hence, SEEG electrodes are advantageous in sampling these areas apart from the deep-seated lesions like heterotopias and hamartomas.[1],[2] MRI negative, discordance between MRI, and electrical and clinical findings, as well as ancillary investigations, represent definitive indications for SEEG implantation.

SEEG electrodes implantation can be accomplished with either frame-based or frameless technique. Frameless stereotactic methods, especially the robotic-guided technique is less laborious as well as faster with a minimal scope for human error compared to the frame-based methods. Efficacy and accuracy of the robotic method is comparable to the conventional frame-based technique as demonstrated in various studies. Stereotactic procedures demanding extreme accuracy like deep brain stimulation, lesioning of hypothalamic hamartomas, psychosurgery, robotic thermocoagulative hemispherotomy and even ventriculoperitoneal shunts in slit like ventricles have been performed robotically.[3],[4],[5],[6],[7],[8],[9],[10]


 » Conclusion Top


Robotic-guided SEEG placement is a safe and elegant technique which is faster and equally efficacious compared to the frame-based technique.

Declaration of patient consent

A full and detailed consent from the patient/guardian has been taken. The patient's identity has been adequately anonymized. If anything related to the patient's identity is shown, adequate consent has been taken from the patient/relative/guardian. The journal will not be responsible for any medico-legal issues arising out of issues related to patient's identity or any other issues arising from the public display of the video.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Taussig D, Chipaux M, Fohlen M, Dorison N, Bekaert O, Ferrand-Sorbets S, et al. Invasive evaluation in children (SEEG vs subdural grids). Seizure 2020;77:43-51.  Back to cited text no. 1
    
2.
Katz JS, Abel TJ. Stereoelectroencephalography versus subdural electrodes for localization of the epileptogenic zone: What is the evidence? Neurotherapeutics 2019;16:59-66.  Back to cited text no. 2
    
3.
Hiremath GK. Robotic deep brain stimulation (R-DBS)-”Awake” deep brain stimulation using the neuromate robot and O-arm. Neurol India 2020;68:S328-32.  Back to cited text no. 3
    
4.
Tassigny D, Soler-Rico M, Delavallée M, Santos SF, El Tahry R, Raftopoulos C. Anterior thalamic nucleus deep brain stimulation for refractory epilepsy: Preliminary results in our first 5 patients. Neurochirurgie 2020;66:252-7.  Back to cited text no. 4
    
5.
Chaitanya G, Romeo AK, Ilyas A, Irannejad A, Toth E, Elsayed G, et al. Robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy: Implantation technique and complications in the first 24 patients. Neurosurg Focus 2020;48:E2.  Back to cited text no. 5
    
6.
Tandon V, Chandra PS, Doddamani RS, Subianto H, Bajaj J, Garg A, et al. Stereotactic radiofrequency thermocoagulation of hypothalamic hamartoma using robotic guidance (ROSA) co-registered with O-arm guidance-preliminary technical note. World Neurosurg 2018;112:267-74.  Back to cited text no. 6
    
7.
Doddamani RS, Tripathi M, Samala R, Agrawal M, Ramanujam B, Bajaj J, et al. Hypothalamic hamartoma and endocrinopathy: A neurosurgeon's perspective. Neurol India 2020;68:S146-53.  Back to cited text no. 7
    
8.
Doddamani RS, Samala R, Agrawal M, Verma R, Kumar N, Chandra PS. Robotic guided bilateral anterior cingulate radiofrequency ablation for obsessive-compulsive disorder. Neurol India 2020;68:S333-6.  Back to cited text no. 8
    
9.
Chandra PS, Doddamani R, Girishan S, Samala R, Agrawal M, Garg A, et al. Robotic thermocoagulative hemispherotomy: Concept, feasibility, outcomes, and safety of a new “bloodless” technique. J Neurosurg Pediatr 2021;2:1-12.  Back to cited text no. 9
    
10.
Doddamani RS, Meena R, Sawarkar D, Singh P, Agrawal D, Singh M, et al. Robot-guided ventriculoperitoneal shunt in slit-like ventricles. Neurol India 2021;69:446-50.  Back to cited text no. 10
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    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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