Indications, technique, and safety profile of insular stereoelectroencephalography electrode implantation in medically intractable epilepsy

OBJECTIVEInsular epilepsy is relatively rare; however, exploring the insular cortex when preoperative workup raises the suspicion of insular epilepsy is of paramount importance for accurate localization of the epileptogenic zone and achievement of seizure freedom. The authors review their clinical experience with stereoelectroencephalography (SEEG) electrode implantation in patients with medically intractable epilepsy and suspected insular involvement.METHODSA total of 198 consecutive cases in which patients underwent SEEG implantation with a total of 1556 electrodes between June 2009 and April 2013 were reviewed. The authors identified patients with suspected insular involvement based on seizure semiology, scalp EEG data, and preoperative imaging (MRI, PET, and SPECT or magnetoencephalography [MEG]). Patients with at least 1 insular electrode based on the postoperative 3D reconstruction of CT fused with the preoperative MRI were included.RESULTSOne hundred thirty-five patients with suspected insular epilepsy underwent insular implantation of a total of 303 electrodes (1–6 insular electrodes per patient) with a total of 562 contacts. Two hundred sixty-eight electrodes (88.5%) were implanted orthogonally through the frontoparietal or temporal operculum (420 contacts). Thirty-five electrodes (11.5%) were implanted by means of an oblique trajectory either through a frontal or a parietal entry point (142 contacts). Nineteen patients (14.07%) had insular electrodes placed bilaterally. Twenty-three patients (17.04% of the insular implantation group and 11.6% of the whole SEEG cohort) were confirmed by SEEG to have ictal onset zones in the insula. None of the patients experienced any intracerebral hemorrhage related to the insular electrodes. After insular resection, 5 patients (33.3%) had Engel Class I outcomes, 6 patients (40%) had Engel Class II, 3 patients (20%) had Engel Class III, and 1 patient (6.66%) had Engel Class IV.CONCLUSIONSInsula exploration with stereotactically placed depth electrodes is a safe technique. Orthogonal electrodes are implanted when the hypothesis suggests opercular involvement; however, oblique electrodes allow a higher insular sampling rate.

Download Full-text

Frameless robot-assisted stereoelectroencephalography in children: technical aspects and comparison with Talairach frame technique

Journal of Neurosurgery Pediatrics ◽

10.3171/2018.1.peds17435 ◽

2018 ◽

Vol 22 (1) ◽

pp. 37-46 ◽

Cited By ~ 24

Author(s):

Taylor J. Abel ◽

René Varela Osorio ◽

Ricardo Amorim-Leite ◽

Francois Mathieu ◽

Philippe Kahane ◽

...

Keyword(s):

Effective Means ◽

Operating Time ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Complication Rates ◽

Class Iii ◽

Intracranial Hemorrhages ◽

Robot Assisted ◽

Pharmacoresistant Epilepsy ◽

Electrode Implantation

OBJECTIVERobot-assisted stereoelectroencephalography (SEEG) is gaining popularity as a technique for localization of the epileptogenic zone (EZ) in children with pharmacoresistant epilepsy. Here, the authors describe their frameless robot-assisted SEEG technique and report preliminary outcomes and relative complications in children as compared to results with the Talairach frame–based SEEG technique.METHODSThe authors retrospectively analyzed the results of 19 robot-assisted SEEG electrode implantations in 17 consecutive children (age < 17 years) with pharmacoresistant epilepsy, and compared these results to 19 preceding SEEG electrode implantations in 18 children who underwent the traditional Talairach frame–based SEEG electrode implantation. The primary end points were seizure-freedom rates, operating time, and complication rates.RESULTSSeventeen children (age < 17 years) underwent a total of 19 robot-assisted SEEG electrode implantations. In total, 265 electrodes were implanted. Twelve children went on to have EZ resection: 4 demonstrated Engel class I outcomes, whereas 2 had Engel class II outcomes, and 6 had Engel class III–IV outcomes. Of the 5 patients who did not have resection, 2 underwent thermocoagulation. One child reported transient paresthesia associated with 2 small subdural hematomas, and 3 other children had minor asymptomatic intracranial hemorrhages. There were no differences in complication rates, rates of resective epilepsy surgery, or seizure freedom rates between this cohort and the preceding 18 children who underwent Talairach frame–based SEEG. The frameless robot-assisted technique was associated with shorter operating time (p < 0.05).CONCLUSIONSFrameless robot-assisted SEEG is a safe and effective means of identifying the EZ in children with pharmacoresistant partial epilepsy. Robot-assisted SEEG is faster than the Talairach frame–based method, and has equivalent safety and efficacy. The former, furthermore, facilitates more electrode trajectory possibilities, which may improve the localization of epileptic networks.

Download Full-text

Surgery for Nontumoral Insular Epilepsy Explored by Stereoelectroencephalography

Neurosurgery ◽

10.1227/neu.0000000000001257 ◽

2016 ◽

Vol 79 (4) ◽

pp. 578-588 ◽

Cited By ~ 27

Author(s):

Guillaume Gras-Combe ◽

Lorella Minotti ◽

Dominique Hoffmann ◽

Alexandre Krainik ◽

Philippe Kahane ◽

...

Keyword(s):

Focal Cortical Dysplasia ◽

Intractable Epilepsy ◽

Insular Cortex ◽

Cavernous Angioma ◽

Cortical Dysplasia ◽

Electrode Placement ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Pharmacoresistant Epilepsy ◽

The Right

Abstract BACKGROUND Hidden by the perisylvian operculi, insular cortex has long been underexplored in the context of epilepsy surgery. Recent studies advocated stereoelectroencephalography (SEEG) as a reliable tool to explore insular cortex and its involvement in intractable epilepsy and suggested that insular seizures could be an underestimated entity. However, the results of insular resection to treat pharmacoresistant epilepsy are rarely reported. OBJECTIVE We report 6 consecutive cases of right insular resection performed based on anatomoelectroclinical correlations provided by SEEG. METHODS Six right-handed patients (3 male, 3 female) with drug-resistant epilepsy underwent comprehensive presurgical evaluation. Based on video electroencephalographic recordings, they all underwent SEEG evaluation with bilateral (n = 4) or unilateral right (n = 2) insular depth electrode placement. All patients had both orthogonal and oblique (1 anterior, 1 posterior) insular electrodes (n = 4-6 electrodes). Preoperative magnetic resonance imaging findings were normal in 4 patients, 1 patient had right insular focal cortical dysplasia, and 1 patient had a right opercular postoperative scar (cavernous angioma). All patients underwent right partial insular corticectomy via the subpial transopercular approach. RESULTS Intracerebral recordings demonstrated an epileptogenic zone confined to the right insula in all patients. After selective insular resection, 5 of 6 patients were seizure free (Engel class I) with a mean follow-up of 36.2 months (range, 18-68 months). Histological findings revealed focal cortical dysplasia in 5 patients and a gliosis scar in 1 patient. All patients had minor transient neurological deficit (eg, facial paresis, dysarthria). CONCLUSION Insular resection based on SEEG findings can be performed safely with a significant chance of seizure freedom.

Download Full-text

Accuracy and Safety of Customized Stereotactic Fixtures for Stereoelectroencephalography in Pediatric Patients

Stereotactic and Functional Neurosurgery ◽

10.1159/000510063 ◽

2020 ◽

pp. 1-8

Author(s):

Constantin Pistol ◽

Andrei Daneasa ◽

Jean Ciurea ◽

Alin Rasina ◽

Andrei Barborica ◽

...

Keyword(s):

Focal Epilepsy ◽

Perioperative Complications ◽

Intractable Epilepsy ◽

Target Point ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Localization Error ◽

Temporal Area ◽

Lateral Entry ◽

Stereotactic Implantation

Stereoelectroencephalography (SEEG) in children with intractable epilepsy presents particular challenges. Their thin and partially ossified cranium, specifically in the temporal area, is prone to fracture while attaching stereotactic systems to the head or stabilizing the head in robot’s field of action. Postponing SEEG in this special population of patients can have serious consequences, reducing their chances of becoming seizure-free and impacting their social and cognitive development. This study demonstrates the safety and accuracy offered by a frameless personalized 3D printed stereotactic implantation system for SEEG investigations in children under 4 years of age. SEEG was carried out in a 3-year-old patient with drug-resistant focal epilepsy, based on a right temporal-perisylvian epileptogenic zone hypothesis. Fifteen intracerebral electrodes were placed using a StarFix patient-customized stereotactic fixture. The median lateral entry point localization error of the electrodes was 0.90 mm, median lateral target point localization error was 1.86 mm, median target depth error was 0.83 mm, and median target point localization error was 1.96 mm. There were no perioperative complications. SEEG data led to a tailored right temporal-insular-opercular resection, with resulting seizure freedom (Engel IA). In conclusion, patient-customized stereotactic fixtures are a safe and accurate option for SEEG exploration in young children.

Download Full-text

Neuronavigation applied to epilepsy monitoring with subdural electrodes

Neurosurgical FOCUS ◽

10.3171/foc/2008/25/9/e21 ◽

2008 ◽

Vol 25 (3) ◽

pp. E21 ◽

Cited By ~ 13

Author(s):

Roukoz B. Chamoun ◽

Vikram V. Nayar ◽

Daniel Yoshor

Keyword(s):

Functional Neuroimaging ◽

Intractable Epilepsy ◽

Epileptic Focus ◽

Epileptogenic Zone ◽

Navigation Systems ◽

Mr Images ◽

Subdural Electrodes ◽

Accurate Localization ◽

Patients With Epilepsy ◽

Neuroimaging Techniques

Accurate localization of the epileptogenic zone is of paramount importance in epilepsy surgery. Despite the availability of noninvasive structural and functional neuroimaging techniques, invasive monitoring with subdural electrodes is still often indicated in the management of intractable epilepsy. Neuronavigation is widely used to enhance the accuracy of subdural grid placement. It allows accurate implantation of the subdural electrodes based on hypotheses formed as a result of the presurgical workup, and can serve as a helpful tool for resection of the epileptic focus at the time of grid explantation. The authors describe 2 additional simple and practical techniques that extend the usefulness of neuronavigation in patients with epilepsy undergoing monitoring with subdural electrodes. One technique involves using the neuronavigation workstation to merge preimplantation MR images with a postimplantation CT scan to create useful images for accurate localization of electrode locations after implantation. A second technique involves 4 holes drilled at the margins of the craniotomy at the time of grid implantation; these are used as fiducial markers to realign the navigation system to the original registration and allow navigation with the merged image sets at the time of reoperation for grid removal and resection of the epileptic focus. These techniques use widely available commercial navigation systems and do not require additional devices, software, or computer skills. The pitfalls and advantages of these techniques compared to alternatives are discussed.

Download Full-text

Depth Electrodes in Pediatric Epilepsy Surgery

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100012944 ◽

2013 ◽

Vol 40 (1) ◽

pp. 48-55 ◽

Cited By ~ 10

Author(s):

Janani Kassiri ◽

Jeff Pugh ◽

Sharon Carline ◽

Laura Jurasek ◽

Thomas Snyder ◽

...

Keyword(s):

Epilepsy Surgery ◽

Pediatric Epilepsy ◽

Surgical Removal ◽

Seizure Freedom ◽

Sufficient Information ◽

Epileptogenic Zone ◽

Depth Electrodes ◽

Depth Electrode ◽

Intractable Seizures ◽

Clinical Scenarios

Abstract:Background:The surgical removal of the epileptogenic zone in medically intractable seizures depends on accurate localization to minimize the neurological sequelae and prevent future seizures. To date, few studies have demonstrated the use of depth electrodes in a pediatric epilepsy population. Here, we report our study of pediatric epilepsy patients at our epilepsy center who were successfully operated for medically intractable seizures following the use of intracranial depth electrodes. In addition, we detail three individuals with distinct clinical scenarios in which depth electrodes were helpful and describe our technical approach to implantation and surgery.Methods:We retrospectively reviewed 18 pediatric epilepsy patients requiring depth electrode studies who presented at the University of Alberta Comprehensive Epilepsy Program between 1999 and 2010 with medically intractable epilepsy. Patients underwent cortical resection following depth electrode placement according to the Comprehensive Epilepsy Program surgical protocols after failure of surface electroencephalogram and magnetic resonance imaging to localize ictal onset zone.Result:The ictal onset zone was successfully identified in all 18 patients. Treatment of all surgical patients resulted in successful seizure freedom (Engel class I) without neurological complications.Conclusion:Intracranial depth electrode use is safe and able to provide sufficient information for the identification of the epileptogenic zone in pediatric epilepsy patients previously not considered for epilepsy surgery.

Download Full-text

Electrocorticography and stereo EEG provide distinct measures of brain connectivity: Implications for network models

10.1101/2020.12.02.20242669 ◽

2020 ◽

Author(s):

John M. Bernabei ◽

T. Campbell Arnold ◽

Preya Shah ◽

Andrew Revell ◽

Ian Z. Ong ◽

...

Keyword(s):

Computational Models ◽

Brain Connectivity ◽

Network Connectivity ◽

Network Models ◽

Brain Network ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Depth Electrodes ◽

Brain Network Connectivity ◽

Patients With Epilepsy

AbstractBrain network models derived from graph theory have the potential to guide functional neurosurgery, and to improve rates of post-operative seizure freedom for patients with epilepsy. A barrier to applying these models clinically is that intracranial EEG electrode implantation strategies vary by center, region and country, from cortical grid & strip electrodes, to purely stereotactic depth electrodes, to a mixture of both. To determine whether models derived from one type of study are broadly applicable to others, we investigate the differences in brain networks mapped by electrocortiography (ECoG) and stereoelectroencephalography (SEEG) in a matched cohort of patients who underwent epilepsy surgery. We show that ECoG and SEEG map broad network structure differently, and demonstrate substantial disparity in the ability of node strength to localize the epileptogenic zone in SEEG compared to ECoG. We demonstrate that eliminating white matter contacts and reducing network nodes to anatomical regions of interest rather than individual contacts improves the ability of these models to distinguish between epileptogenic and non-epileptogenic regions in SEEG. Our findings suggest that effectively applying computational models to localize epileptic networks requires accounting for the effects of spatial sampling, particularly when analyzing both ECoG and SEEG recordings in the same cohort. Finally, we share all code and data in this study, aiming for our findings to accelerate research in brain network connectivity in epilepsy and beyond.

Download Full-text

Forecasting Seizure Freedom After Epilepsy Surgery Assessing Concordance Between Noninvasive and StereoEEG Findings

Neurosurgery ◽

10.1093/neuros/nyaa322 ◽

2020 ◽

Vol 88 (1) ◽

pp. 113-121 ◽

Cited By ~ 1

Author(s):

Reinaldo Uribe San Martin ◽

Roberta Di Giacomo ◽

Roberto Mai ◽

Francesca Gozzo ◽

Veronica Pelliccia ◽

...

Keyword(s):

Epilepsy Surgery ◽

Fdg Pet ◽

Cox Regression ◽

Good Prognosis ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Cox Regression Analysis ◽

Accurate Localization ◽

Positron Emission ◽

Drug Resistant Epilepsy

Abstract BACKGROUND Accurate localization of the probable Epileptogenic Zone (EZ) from presurgical studies is crucial for achieving good prognosis in epilepsy surgery. OBJECTIVE To evaluate the degree of concordance at a sublobar localization derived from noninvasive studies (video electroencephalography, EEG; magnetic resonance imaging, MRI; 18-fluorodeoxyglucose positron emission tomography FDG-PET, FDG-PET) and EZ estimated by stereoEEG, in forecasting seizure recurrence in a long-term cohort of patients with focal drug-resistant epilepsy. METHODS We selected patients with a full presurgical evaluation and with postsurgical outcome at least 1 yr after surgery. Multivariate Cox regression analysis for seizure freedom (Engel Ia) was performed. RESULTS A total of 74 patients were included, 62.2% were in Engel class Ia with a mean follow-up of 2.8 + 2.4 yr after surgery. In the multivariate analysis for Engel Ia vs >Ib, complete resection of the EZ found in stereoEEG (hazard ratio, HR: 0.24, 95%CI: 0.09-0.63, P = .004) and full concordance between FDG-PET and stereoEEG (HR: 0.11, 95%CI: 0.02-0.65, P = .015) portended a more favorable outcome. Most of our results were maintained when analyzing subgroups of patients. CONCLUSION The degree of concordance between noninvasive studies and stereoEEG may help to forecast the likelihood of cure before performing resective surgery, particularly using a sublobar classification and comparing the affected areas in the FDG-PET with EZ identified with stereoEEG.

Download Full-text

Resective Epilepsy Surgery for Tuberous Sclerosis in Children

Neurosurgery ◽

10.1227/neu.0000000000000875 ◽

2015 ◽

Vol 77 (4) ◽

pp. 517-524 ◽

Cited By ~ 43

Author(s):

Aria Fallah ◽

Shaun D. Rodgers ◽

Alexander G. Weil ◽

Sumeet Vadera ◽

Alireza Mansouri ◽

...

Keyword(s):

Tuberous Sclerosis ◽

Epilepsy Surgery ◽

Medical Center ◽

Cleveland Clinic ◽

Intractable Epilepsy ◽

Seizure Outcome ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Children's Hospital ◽

Children’S Hospital

Abstract BACKGROUND: There are no established variables that predict the success of curative resective epilepsy surgery in children with tuberous sclerosis complex (TSC). OBJECTIVE: We performed a multicenter observational study to identify preoperative factors associated with seizure outcome in children with TSC undergoing resective epilepsy surgery. METHODS: A retrospective chart review was performed in eligible children at New York Medical Center, Miami Children's Hospital, Cleveland Clinic Foundation, BC Children's Hospital, Hospital for Sick Children, and Sainte-Justine Hospital between January 2005 and December 2013. A time-to-event analysis was performed. The “event” was defined as seizures after resective epilepsy surgery. RESULTS: Seventy-four patients (41 male) were included. The median age of the patients at the time of surgery was 120 months (range, 3-216 months). The median time to seizure recurrence was 24.0 ± 12.7 months. Engel Class I outcome was achieved in 48 (65%) and 37 (50%) patients at 1- and 2-year follow-up, respectively. On univariate analyses, younger age at seizure onset (hazard ratio [HR]: 2.03, 95% confidence interval [CI]: 1.03-4.00, P = .04), larger size of predominant tuber (HR: 1.03, 95% CI: 0.99-1.06, P = .12), and resection larger than a tuberectomy (HR: 1.86, 95% CI: 0.92-3.74, P = .084) were associated with a longer duration of seizure freedom. In multivariate analyses, resection larger than a tuberectomy (HR: 2.90, 95% CI: 1.17-7.18, P = .022) was independently associated with a longer duration of seizure freedom. CONCLUSION: In this large consecutive cohort of children with TSC and medically intractable epilepsy, a greater extent of resection (more than just the tuber) is associated with a greater probability of seizure freedom. This suggests that the epileptogenic zone may include the cortex surrounding the presumed offending tuber.

Download Full-text

Single-Institutional Experience of Chronic Intracranial Electroencephalography Based on the Combined Usage of Subdural and Depth Electrodes

Brain Sciences ◽

10.3390/brainsci11030307 ◽

2021 ◽

Vol 11 (3) ◽

pp. 307

Author(s):

Yutaro Takayama ◽

Naoki Ikegaya ◽

Keiya Iijima ◽

Yuiko Kimura ◽

Suguru Yokosako ◽

...

Keyword(s):

Intractable Epilepsy ◽

Seizure Freedom ◽

Brain Surface ◽

Depth Electrodes ◽

Significant Difference ◽

Institutional Experience ◽

Temporal Structures ◽

Drug Resistant Epilepsy ◽

Intracranial Electroencephalography ◽

The Brain

Implantation of subdural electrodes on the brain surface is still widely performed as one of the “gold standard methods” for the presurgical evaluation of epilepsy. Stereotactic insertion of depth electrodes to the brain can be added to detect brain activities in deep-seated lesions to which surface electrodes are insensitive. This study tried to clarify the efficacy and limitations of combined implantation of subdural and depth electrodes in intractable epilepsy patients. Fifty-three patients with drug-resistant epilepsy underwent combined implantation of subdural and depth electrodes for long-term intracranial electroencephalography (iEEG) before epilepsy surgery. The detectability of early ictal iEEG change (EIIC) were compared between the subdural and depth electrodes. We also examined clinical factors including resection of MRI lesion and EIIC with seizure freedom. Detectability of EIIC showed no significant difference between subdural and depth electrodes. However, the additional depth electrode was useful for detecting EIIC from apparently deep locations, such as the insula and mesial temporal structures, but not in detecting EIIC in patients with ulegyria (glial scar). Total removal of MRI lesion was associated with seizure freedom. Depth electrodes should be carefully used after consideration of the suspected etiology to avoid injudicious usage.

Download Full-text

Technique, Results, and Complications Related to Robot-Assisted Stereoelectroencephalography

Neurosurgery ◽

10.1227/neu.0000000000001034 ◽

2015 ◽

Vol 78 (2) ◽

pp. 169-180 ◽

Cited By ~ 121

Author(s):

Jorge González-Martínez ◽

Juan Bulacio ◽

Susan Thompson ◽

John Gale ◽

Saksith Smithason ◽

...

Keyword(s):

Focal Epilepsy ◽

Interquartile Range ◽

Implantation Technique ◽

Target Point ◽

Seizure Outcome ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Robot Assisted ◽

Depth Electrodes

ABSTRACT BACKGROUND: Robot-assisted stereoelectroencephalography (SEEG) may represent a simplified, precise, and safe alternative to the more traditional SEEG techniques. OBJECTIVE: To report our clinical experience with robotic SEEG implantation and to define its utility in the management of patients with medically refractory epilepsy. METHODS: The prospective observational analyses included all patients with medically refractory focal epilepsy who underwent robot-assisted stereotactic placement of depth electrodes for extraoperative brain monitoring between November 2009 and May 2013. Technical nuances of the robotic implantation technique are presented, as well as an analysis of demographics, time of planning and procedure, seizure outcome, in vivo accuracy, and procedure-related complications. RESULTS: One hundred patients underwent 101 robot-assisted SEEG procedures. Their mean age was 33.2 years. In total, 1245 depth electrodes were implanted. On average, 12.5 electrodes were implanted per patient. The time of implantation planning was 30 minutes on average (range, 15-60 minutes). The average operative time was 130 minutes (range, 45-160 minutes). In vivo accuracy (calculated in 500 trajectories) demonstrated a median entry point error of 1.2 mm (interquartile range, 0.78-1.83 mm) and a median target point error of 1.7 mm (interquartile range, 1.20-2.30 mm). Of the group of patients who underwent resective surgery (68 patients), 45 (66.2%) gained seizure freedom status. Mean follow-up was 18 months. The total complication rate was 4%. CONCLUSION: The robotic SEEG technique and method were demonstrated to be safe, accurate, and efficient in anatomically defining the epileptogenic zone and subsequently promoting sustained seizure freedom status in patients with difficult-to-localize seizures.

Download Full-text