Stereoelectroencephalography in children: a review

Applications and Predictors of Outcomes Following Stereo-Electroencephalography in Pediatric Patients With Drug-Resistant Epilepsy

AIMS

This study aims to evaluate the role of stereo-electroencephalography (SEEG) in managing pediatric patients with drug-resistant epilepsy. We further explore prognostic factors influencing surgical outcomes following SEEG-guided resective or disconnective surgery.

METHODS

A retrospective review was conducted on pediatric patients who underwent SEEG at the Pediatric Epilepsy Center, Peking University First Hospital, between July 2017 and July 2022. Univariate and multivariate analyses identified key predictors for SEEG-guided surgery. Kaplan-Meier survival analysis was employed to estimate the seizure-free rate, and further statistical tests were applied to evaluate factors associated with seizure outcomes.

RESULTS

Among the 148 children included in this study, 102 underwent SEEG-guided resective/disconnective surgery. Multivariate regression identified age at surgery (p < 0.05, 95% CI 0.190-0.997) as an independent predictor for selecting resective/disconnective surgery. The seizure-free rate in patients who underwent SEEG-guided surgery was 69.6%. Multivariate regression confirmed that total resection with lesional MRI (p < 0.05, 95% CI 0.012-0.186) and FCD type II (p < 0.05, 95% CI 0.051-0.851) were strong predictors of seizure freedom.

CONCLUSIONS

SEEG plays a crucial role in pediatric epilepsy surgery, particularly in children under 6 years old. Total resection with lesional MRI and FCD type II was the most favorable prognostic predictor for achieving seizure freedom in children undergoing SEEG-guided surgery.

Accuracy of frameless robot-assisted stereoelectroencephalography depth electrode implantation using the neurolocate registration system in paediatric patients

BACKGROUND

We assessed the accuracy and performed a directional analysis of robot-assisted implantation of stereoelectroencephalography (SEEG) depth electrodes in children using the frameless neurolocate 3D registration module.

METHODS

Thirteen children with epilepsy undergoing stereotactic robot-assisted insertion of SEEG electrodes were included. Six children were operated on with standard frame-based registration while 7 with the use of the frameless neurolocate registration module. Accuracy and directional analysis of orthogonal and oblique electrodes were assessed by calculating the absolute error, the radial error, the angle error, and the Euclidean distance.

RESULTS

Of 172 electrodes 89 were implanted in the 6 standard frame-based mode patients and 83 in the 7 neurolocate patients. The overall mean age was 12.2 ± 4.4 years (range 2-17). The mean number of electrodes in each patient was 13.2 ± 2.04 (range 9-17). The median radial error of electrode placement in the neurolocate patients (1.08 mm, [IQR: 1.26]) was significantly less when compared with standard frame-based mode patients (1.49 mm, [IQR 1.25)]; p = 0.04). The same applies to the median angle error which was in the neurolocate group 1.61° [IQR: 1.46] and in the standard frame-based group 2.16° [IQR: 2.09]; p = 0.019. Directional analysis of electrode trajectories in the neurolocate group showed that in the x-axis the median absolute error of orthogonal electrodes (0.4 mm, [IQR: 0.475]) was less when compared with oblique electrodes (0.7 mm, [IQR: 1.2]; p = 0.007). In the standard frame-based mode group in the y-axis, the median absolute error of orthogonal electrodes (0.7 mm, [IQR: 1.3]) was less compared with oblique electrodes (1.25 mm, [IQR: 1.6]; p = 0.03).

CONCLUSION

In paediatric patients, robot-assisted SEEG depth electrode implantation with the non-invasive and easy-to-use frameless neurolocate registration module is a consistent and accurate procedure.

A Multivariate Approach to Quantifying Risk Factors Impacting Stereotactic Robotic-Guided Stereoelectroencephalography

BACKGROUND AND OBJECTIVES

Stereoelectroencephalography (SEEG) is an important method for invasive monitoring to establish surgical candidacy in approximately half of refractory epilepsy patients. Identifying factors affecting lead placement can mitigate potential surgical risks. This study applies multivariate analyses to identify perioperative factors affecting stereotactic electrode placement.

METHODS

We collected registration and accuracy data for consecutive patients undergoing SEEG implantation between May 2022 and November 2023. Stereotactic robotic guidance, using intraoperative imaging and a novel frame-based fiducial, was used for planning and SEEG implantation. Entry-point (EE), target-point (TE), and angular errors were measured, and statistical univariate and multivariate linear regression analyses were performed.

RESULTS

Twenty-seven refractory epilepsy patients (aged 15-57 years) undergoing SEEG were reviewed. Sixteen patients had unilateral implantation (10 left-sided, 6 right-sided); 11 patients underwent bilateral implantation. The mean number of electrodes per patient was 18 (SD = 3) with an average registration mean error of 0.768 mm (SD = 0.108). Overall, 486 electrodes were reviewed. Univariate analysis showed significant correlations of lead error with skull thickness (EE: P = .003; TE: P = .012); entry angle (EE: P < .001; TE: P < .001; angular error: P = .030); lead length (TE: P = .020); and order of electrode implantation (EE: P = .003; TE: P = .001). Three multiple linear regression models were used. All models featured predictors of implantation region (157 temporal, 241 frontal, 79 parietal, 9 occipital); skull thickness (mean = 5.80 mm, SD = 2.97 mm); order (range: 1-23); and entry angle in degrees (mean = 75.47, SD = 11.66). EE and TE error models additionally incorporated lead length (mean = 44.08 mm, SD = 13.90 mm) as a predictor. Implantation region and entry angle were significant predictors of error (P ≤ .05).

CONCLUSION

Our study identified 2 primary predictors of SEEG lead error, region of implantation and entry angle, with nonsignificant contributions from lead length or order of electrode placement. Future considerations for SEEG may consider varying regional approaches and angles for more optimal accuracy in lead placement.

The surgical interval between robot-assisted SEEG and epilepsy resection surgery is an influencing factor of SSI

BACKGROUND

In recent years, the development of robotic neurosurgery has brought many benefits to patients, but there are few studies on the occurrence of surgical site infection (SSI) after robot-assisted stereoelectroencephalography (SEEG). The purpose of this study was to collect relevant data from robot-assisted SEEG over the past ten years and to analyze the influencing factors and economic burden of surgical site infection.

METHODS

Basic and surgical information was collected for all patients who underwent robot-assisted SEEG from January 2014 to December 2023. Logistic regression was used to analyze the factors influencing SSI according to different subgroups (radiofrequency thermocoagulation or epilepsy resection surgery).

RESULTS

A total of 242 subjects were included in this study. The risk of SSI in the epilepsy resection surgery group (18.1%) was 3.5 times greater than that in the radiofrequency thermocoagulation group (5.1%) (OR 3.49, 95% CI 1.39 to 9.05); this difference was statistically significant. SSI rates in the epilepsy resection surgery group were associated with shorter surgical intervals (≤ 9 days) and higher BMI (≥ 23 kg/m2) (6.1 and 5.2 times greater than those in the control group, respectively). Hypertension and admission to the intensive care unit (ICU) were risk factors for SSI in the radiofrequency thermocoagulation group. Patients with SSIs had $21,231 more total hospital costs, a 7-day longer hospital stay, and an 8-day longer postoperative hospital stay than patients without SSI.

CONCLUSIONS

The incidence of SSI in patients undergoing epilepsy resection after stereoelectroencephalography was higher than that in patients undergoing radiofrequency thermocoagulation. For patients undergoing epilepsy resection surgery, prolonging the interval between stereoelectroencephalography and epilepsy resection surgery can reduce the risk of SSI; At the same time, for patients receiving radiofrequency thermocoagulation treatment, it is not recommended to enter the ICU for short-term observation if the condition permits.

Advanced approaches in Pediatric Epilepsy surgery

While recent technological advancements are reshaping the landscape of surgical epilepsy management, the established techniques of resective and disconnective surgeries guided by electrographic monitoring remain the workhorse interventions for the management of refractory seizures and have the highest likelihood of achieving complete seizure resolution. Here we discuss examples of recent developments in surgical approaches and techniques for resective and disconnective surgeries with discussion of their indications and potential advantages.

Advances in pediatric neuroanesthesia practices

The field of pediatric neuroanesthesia has evolved with concurrent changes in pediatric neurosurgical practice. Ongoing pediatric neuroanesthesia investigations provide novel insights into developmental cerebrovascular physiology, neurosurgical technology, and clinical outcomes. Minimally invasive neurosurgical procedures appear to be associated with lower complication rates and length of stay. This review will discuss blood sparing techniques, regional anesthesia, and postoperative disposition. Collectively, these innovations appear to be safe in pediatric neurosurgical patients with potential benefits, but more data is needed for more definitive long-term outcomes.

Accuracy and Utility of Frameless Stereotactic Placement of Stereoelectroencephalography Electrodes

BACKGROUND

Successful surgery for epilepsy hinges on identification of the epileptogenic focus. Stereoelectroencephalography (sEEG) is the most effective way to identify most seizure foci. There are multiple methods of inserting depth electrodes, including frame-based, frameless, and robot-assisted techniques. Studies have shown the accuracy of frame-based and robotic-assisted techniques to be statistically similar, while only one study has detailed the frameless sEEG insertion technique.

METHODS

Patients underwent placement of sEEG depth electrodes using frameless stereotaxy from September 2019 to September 2021 at Geisinger Medical Center by a single surgeon. Seizure history, electrode placement accuracy relative to the planned trajectories, surgical times, success rate of identifying the epileptogenic focus, and subsequent seizure control rates after surgical treatment were documented.

RESULTS

Data were available for 21 patients and 181 electrodes inserted using the VarioGuide frameless stereotactic system. Each insertion took an average of 14.5 minutes per lead. Average entry variance was 2.7 mm with an average target variance of 4.6 mm. The epileptogenic focus was identified in 19 of 21 patients, and further surgical treatment was performed in 18 of 21 patients (85.7%).

CONCLUSIONS

VarioGuide frameless stereotaxy for sEEG placement is comparable to frame-based and robotic-assisted techniques with statistically similar rates of epileptic focus identification. Lead placement accuracy is slightly lower and time per lead is slightly higher relative to robot-assisted surgeries. When a robot system is unavailable, surgeons can consider using a frameless stereotactic technique for sEEG insertion, allowing patients to benefit from a similarly high rate of epileptic zone identification.

Robotic-Assisted Stereoelectroencephalography: A Systematic Review and Meta-Analysis of Safety, Outcomes, and Precision in Refractory Epilepsy Patients

Robotic assistance in stereoelectroencephalography (SEEG) holds promising potential for enhancing accuracy, efficiency, and safety during electrode placement and surgical procedures. This systematic review and meta-analysis, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and International Prospective Register of Systematic Reviews (PROSPERO) registration, delves into the latest advancements and implications of robotic systems in SEEG, while meticulously evaluating outcomes and safety measures. Among 855 patients suffering from medication-refractory epilepsy who underwent SEEG in 29 studies, averaging 24.6 years in age, the most prevalent robots employed were robotic surgical assistant (ROSA) (450 patients), Neuromate (207), Sinovation (140), and ISys1 (58). A total of 8,184 electrodes were successfully implanted, with an average operative time of 157.2 minutes per procedure and 15.1 minutes per electrode, resulting in an overall mean operative time of 157.7 minutes across all studies. Notably, the mean target point error (TPE) stood at 2.13 mm, the mean entry point error (EPE) at 1.48 mm, and postoperative complications occurred in 7.69% of robotically assisted (RA) SEEG cases (60), with 85% of these complications being asymptomatic. This comprehensive analysis underscores the safety and efficacy of RA-SEEG in patients with medication-refractory epilepsy, characterized by low complication rates, reduced operative time, and precise electrode placement, supporting its widespread adoption in clinical practice, with no discernible differences noted among the various robotic systems.

Accuracy of Depth Electrodes is Not Time-Dependent in Robot-Assisted Stereoelectroencephalography in a Pediatric Population

BACKGROUND AND OBJECTIVES

Robot-assisted stereoelectroencephalography (sEEG) is steadily supplanting traditional frameless and frame-based modalities for minimally invasive depth electrode placement in epilepsy workup. Accuracy rates similar to gold-standard frame-based techniques have been achieved, with improved operative efficiency. Limitations in cranial fixation and placement of trajectories in pediatric patients are believed to contribute to a time-dependent accumulation of stereotactic error. Thus, we aim to study the impact of time as a marker of cumulative stereotactic error during robotic sEEG.

METHODS

All patients between October 2018 and June 2022 who underwent robotic sEEG were included. Radial errors at entry and target points as well as depth and Euclidean distance errors were collected for each electrode, excluding those with errors over 10 mm. Target point errors were standardized by planned trajectory length. ANOVA and error rates over time were analyzed using GraphPad Prism 9.

RESULTS

Forty-four patients met inclusion criteria for a total of 539 trajectories. Number of electrodes placed ranged from 6 to 22. Average root mean squared error was 0.45 ± 0.12 mm. Average entry, target, depth, and Euclidean distance errors were 1.12 ± 0.41 mm, 1.46 ± 0.44 mm, -1.06 ± 1.43 mm, and 3.01 ± 0.71 mm, respectively. There was no significant increased error with each sequential electrode placed (entry error P -value = .54, target error P -value = .13, depth error P -value = .22, Euclidean distance P -value = .27).

CONCLUSION

No decremental accuracy over time was observed. This may be secondary to our workflow which prioritizes oblique and longer trajectories first and then into less error-prone trajectories. Further study on the effect of level of training may reveal a novel difference in error rates.

Consensus on pediatric epilepsy surgery for young children: an investigation by the China Association Against Epilepsy task force on epilepsy surgery

Researchers have widely acknowledged the therapeutic value of epilepsy surgery for drug-resistant epilepsy. Nonetheless, there is a substantial gap in the surgical treatment for appropriate candidates owing to several factors, particularly in the population of young children. To standardize the protocols of preoperative evaluation and surgery of young children for epilepsy surgery, the China Association Against Epilepsy has appointed an expert task force to standardize the protocols of preoperative evaluation and surgery in pediatric epilepsy patients. It adopted the modified Delphi method and performed two rounds of surveys through an anonymous inquiry among 75 experts from four subgroups including pediatric neurologists, epileptologists, pediatric epilepsy surgeons, and functional neurosurgeons. The survey contents contained: (1) the participants, comprising children aged ≤ 6 years; (2) adopted DRE definition proposed by the International League Against Epilepsy in 2010; and (3) investigated epilepsy surgery, principally referring to curative epilepsy surgeries. The neuromodulation therapies were excluded because of the differences in treatment mechanisms from the above-mentioned surgeries. According to the Delphi process, a consensus was achieved for most aspects by incorporating two rounds of surveys including preoperative assessment, surgical strategies and techniques, and perioperative and long-term postoperative management, despite controversial opinions on certain items. We hope the results of this consensus will improve the level of surgical treatment and management of intractable epilepsy in young children.

Virtual reality-based 3-dimensional localization of stereotactic EEG (SEEG) depth electrodes and related brain anatomy in pediatric epilepsy surgery

INTRODUCTION

The increasing use of stereoelectroencephalography (SEEG) in the USA and the need for three-dimensional (3D) appreciation of complex spatial relationships between implanted stereotactic EEG depth electrodes and surrounding brain and cerebral vasculature are a challenge to clinicians who are used to two-dimensional (2D) appreciation of cortical anatomy having been traditionally trained on 2D radiologic imaging. Virtual reality and its 3D renderings have grown increasingly common in the multifaceted practice of neurosurgery. However, there exists a paucity in the literature regarding this emerging technology in its utilization of epilepsy surgery.

METHODS

An IRB-approved, single-center retrospective study identifying all SEEG pediatric patients in which virtual reality was applied was observed.

RESULTS

Of the 46 patients identified who underwent an SEEG procedure, 43.5% (20/46) had a 3D rendering (3DR) of their SEEG depth electrodes. All 3DRs were used during patient-family education and discussion among the Epilepsy multidisciplinary team meetings, while 35% (7/20) were used during neuronavigation in surgery. Three successful representative cases of its application were presented.

DISCUSSION

Our institution's experience regarding virtual reality in the 3D representation of SEEG depth electrodes and the application to pre-surgical planning, patient-family education, multidisciplinary communication, and intraoperative neuronavigation demonstrate its applicability in comprehensive epilepsy patient care.

Stereoelectroencephalography in the very young: Case report

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To the best of our knowledge this is the youngest reported patient implanted with SEEG.

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Accurate and safe SEEG surgery may be feasible in patients as young as 17 months-old.

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Robotic SEEG with standard tools may be effectively used in this very young population.

Stereoelectroencephalography (SEEG) is an increasingly popular invasive monitoring approach to epilepsy surgery in patients with drug-resistant epilepsies. The technique allows a three-dimensional definition of the epileptogenic zones (EZ) in the brain. It has been shown to be safe and effective in adults and older children but has been used sparingly in children less than two years old due to concerns about pin fixation in thin bone, registration accuracy, and bolt security. As such, most current series of pediatric invasive EEG explorations do not include young participants, and, when they do, SEEG is often not utilized for these patients. Recent national survey data further suggests SEEG is infrequently utilized in very young patients. We present a novel case of SEEG used to localize the EZ in a 17-month-old patient with thin cranial bone, an open fontanelle, and severe drug-resistant epilepsy due to tuberous sclerosis complex (TSC), with excellent accuracy, surgical results, and seizure remission.

Smaller Knife, Fewer Seizures? Recent Advances in Minimally Invasive Techniques in Pediatric Epilepsy Surgery

Children with drug-resistant epilepsy are at high risk for developmental delay, increased mortality, psychiatric comorbidities, and requiring assistance with activities of daily living. Despite the advent of new and effective pharmacologic therapies, about one in 5 children will develop drug-resistant epilepsy, and most of these children continue to have seizures despite trials of other medication. Epilepsy surgery is often a safe and effective option which may offer seizure freedom or at least a significant reduction in seizure burden in many children. However, despite published evidence of safety and efficacy, epilepsy surgery remains underutilized in the pediatric population. Patient and family fears about the risks of surgery may contribute to this gap. Less invasive surgical techniques may be more palatable to children with epilepsy and their caregivers. In this review, we present recent advances in minimally invasive techniques for the surgical treatment of epilepsy as well as intriguing possibilities for the future. We describe the indications for, benefits of, and limits to minimally-invasive techniques including Stereo-encephalography, laser interstitial thermal ablation, deep brain stimulation, focused ultrasound, stereo-encephalography-guided radiofrequency ablation, endoscopic disconnections, and responsive neurostimulation.

The UK experience of stereoelectroencephalography in children: An analysis of factors predicting the identification of a seizure-onset zone and subsequent seizure freedom

OBJECTIVE

Stereoelectroencephalography (SEEG) is being used more frequently in the pre-surgical evaluation of children with focal epilepsy. It has been shown to be safe in children, but there are no multicenter studies assessing the rates and factors associated with the identification of a putative seizure-onset zone (SOZ) and subsequent seizure freedom following SEEG-guided epilepsy surgery.

METHODS

Multicenter retrospective cohort study of all children undergoing SEEG at six of seven UK Children's Epilepsy Surgery Service centers from 2014 to 2019. Demographics, noninvasive evaluation, SEEG, and operative factors were analyzed to identify variables associated with the identification of a putative SOZ and subsequent seizure freedom following SEEG-guided epilepsy surgery.

RESULTS

One hundred thirty-five patients underwent 139 SEEG explorations using a total of 1767 electrodes. A putative SOZ was identified in 117 patients (85.7%); odds of successfully finding an SOZ were 6.4 times greater for non-motor seizures compared to motor seizures (p = 0.02) and 3.6 times more if four or more seizures were recorded during SEEG (p = 0.03). Of 100 patients undergoing surgical treatment, 47 (47.0%) had an Engel class I outcome at a median follow-up of 1.3 years; the only factor associated with outcome was indication for SEEG (p = 0.03); an indication of "recurrence following surgery/treatment" had a 5.9 times lower odds of achieving seizure freedom (p = 0.002) compared to the "lesion negative" cohort, whereas other indications ("lesion positive, define extent," "lesion positive, discordant noninvasive investigations" and "multiple lesions") were not statistically significantly different.

SIGNIFICANCE

This large nationally representative cohort illustrates that SEEG-guided surgery can still achieve high rates of seizure freedom. Seizure semiology and the number of seizures recorded during SEEG are important factors in the identification of a putative SOZ, and the indication for SEEG is an important factor in postoperative outcomes.

Hemorrhage Rates After Implantation and Explantation of Stereotactic Electroencephalography: Reevaluating Patients' Risk

OBJECTIVE

Stereoelectroencephalography (sEEG), despite its established usefulness, has not been thoroughly evaluated for its adverse events profile. In this study, hemorrhage rates were evaluated both per patient and per lead placed not only in the immediate postoperative period, but also over the course of admission and after explantation when available.

METHODS

This is a single-center retrospective study of pediatric and adult patients undergoing sEEG lead placement at a large urban hospital. All available postoperative imaging was reviewed for the presence of hemorrhage, including any imaging occurring throughout admission as well as within 1 month of lead explantation. Age and number of leads placed per procedure were compared using an unpaired t test assuming unequal variance.

RESULTS

A total of 1855 leads were placed in 147 cases. The mean age was 30.4 ±15.0 and the male/female ratio was 47:53. 9 leads (0.49%) in 9 cases (6.12%) were involved with postimplantation hemorrhage occurring on postoperative day 0.44 on average. Postexplantation imaging was available for 45 cases. Seven leads (1.40%) in 7 cases (15.56%) were involved with postexplantation hemorrhage occurring on average on postoperative day 1.42. There was a significant difference in mean age between patients with postexplantation hemorrhage versus control (45.0 vs. 32.2; P = 0.0277). No cases of hemorrhage required surgical intervention and no patients had permanent neurologic deficit.

CONCLUSIONS

Hemorrhage after sEEG lead implantation and explantation may be more common than previously reported. Consistent postexplantation imaging may be of clinical benefit in detecting hemorrhage that precludes patients from immediate discharge, particularly in older patients.

Stereotactic depth electrode placement surgery in paediatric and adult patients with the Neuromate robotic device: Accuracy, complications and epileptological results

OBJECTIVE

The number of patients requiring depth electrode implantation for invasive video EEG diagnostics increases in most epilepsy centres. Here we report on our institutional experience with frameless robot-assisted stereotactic placement of intracerebral depth electrodes using the Neuromate® stereotactic robot-system.

METHODS

We identified all patients who had undergone robot-assisted stereotactic placement of intracerebral depth electrodes for invasive extra-operative epilepsy monitoring between September 2013 and March 2020. We studied technical (placement) and diagnostic accuracy of the robot-assisted procedure, associated surgical complications and procedural time requirements.

RESULTS

We evaluated a total of 464 depth electrodes implanted in 74 patients (mean 6 per patient, range 1-12). There were 27 children and 47 adults (age range: 3.6-64.6 yrs.). The mean entry and target point errors were 1.82±1.15 and 1.98±1.05 mm. Target and entry point errors were significantly higher in paediatric vs. adult patients and for electrodes targeting the temporo-mesial region. There were no clinically relevant haemorrhages and no infectious complications. Mean time for the placement of one electrode was 37±14 min and surgery time per electrode decreased with the number of electrodes placed. 55 patients (74.3%) underwent definitive surgical treatment. 36/51 (70.1%) patients followed for >12 months or until seizure recurrence became seizure-free (ILAE I).

CONCLUSION

Frameless robot-guided stereotactic placement of depth electrodes with the Neuromate® stereotactic robot-system is safe and feasible even in very young children, with good in vivo accuracy and high diagnostic precision. The surgical workflow is time-efficient and further improves with increasing numbers of implanted electrodes.

Contemporaneous evaluation of patient experience, surgical strategy, and seizure outcomes in patients undergoing stereoelectroencephalography or subdural electrode monitoring

OBJECTIVE

Intracranial electrographic localization of the seizure onset zone (SOZ) can guide surgical approaches for medically refractory epilepsy patients, especially when the presurgical workup is discordant or functional cortical mapping is required. Minimally invasive stereotactic placement of depth electrodes, stereoelectroencephalography (SEEG), has garnered increasing use, but limited data exist to evaluate its postoperative outcomes in the context of the contemporaneous availability of both SEEG and subdural electrode (SDE) monitoring. We aimed to assess the patient experience, surgical intervention, and seizure outcomes associated with these two epileptic focus mapping techniques during a period of rapid adoption of neuromodulatory and ablative epilepsy treatments.

METHODS

We retrospectively reviewed 66 consecutive adult intracranial electrode monitoring cases at our institution between 2014 and 2017. Monitoring was performed with either SEEG (n = 47) or SDEs (n = 19).

RESULTS

Both groups had high rates of SOZ identification (SEEG 91.5%, SDE 88.2%, P = .69). The majority of patients achieved Engel class I (SEEG 29.3%, SDE 35.3%) or II outcomes (SEEG 31.7%, SDE 29.4%) after epilepsy surgery, with no significant difference between groups (P = .79). SEEG patients reported lower median pain scores (P = .03) and required less narcotic pain medication (median = 94.5 vs 594.6 milligram morphine equivalents, P = .0003). Both groups had low rates of symptomatic hemorrhage (SEEG 0%, SDE 5.3%, P = .11). On multivariate logistic regression, undergoing resection or ablation (vs responsive neurostimulation/vagus nerve stimulation) was the only significant independent predictor of a favorable outcome (adjusted odds ratio = 25.4, 95% confidence interval = 3.48-185.7, P = .001).

SIGNIFICANCE

Although both SEEG and SDE monitoring result in favorable seizure control, SEEG has the advantage of superior pain control, decreased narcotic usage, and lack of routine need for intensive care unit stay. Despite a heterogenous collection of epileptic semiologies, seizure outcome was associated with the therapeutic surgical modality and not the intracranial monitoring technique. The potential for an improved postoperative experience makes SEEG a promising method for intracranial electrode monitoring.

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

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.

Individualized stereoelectroencephalography evaluation and navigated resection in medically refractory pediatric epilepsy

Pediatric patients frequently require invasive exploration with intracranial electrodes to achieve high-resolution delineation of the epileptogenic zones (EZ). We intend to discuss the efficacy and safety of stereoelectroencephalophraphy (SEEG) monitoring in pediatric patients with difficulty to localize the EZ. We retrospectively analyzed presurgical findings, SEEG data, resections, and outcomes of a series of 72 consecutive pediatric patients (<18 yrs) who had medically refractory epilepsy and received SEEG recording between January 2015 and September 2019. There were 20 girls and 52 boys with a mean age of 10.13 ± 4.11 years old (range: 1.8-18 years). Twenty-seven patients (37.5%) had nonlesional magnetic resonance imagings (MRIs). In total, 744 electrodes were implanted for an average of 10.33 ± 2.53 (range: 3-18) electrodes per patient. Twenty-eight explorations were unilateral (17 left and 11 right), and 44 explorations were bilateral (12 of which was predominately one side). The average monitoring period in days for the SEEG was 8.99 ± 5.79 (range: 3-25) days. The EZ could be located in 67 (94.4%) patients for the initial implantation according to SEEG monitoring. Lobectomy was performed in 12 patients (17.9%), of those anterior temporal lobectomy (ATL) was performed in 8 cases (11.9%) and insular plus was 2 cases (3.0%), multilobectomy resections in 15 cases (22.4%), tailored cortical resections in 37 cases (55.2%), and corpus callosotomy plus in 2 cases (3.0%). The average follow-up was 18.1 ± 7.53 months (range: 6-54). Forty-three of 67 patients (64.2%) were Engel class I, 12 patients (17.9%) were Engel class II, 10 patients (14.9%) were Engel class III, and an additional 2 patients (3.0%) were Engel class IV. In the SEEG implantation series, no child experienced serious or permanent morbidity. One patient (1.4%) experienced symptomatic intracranial hemorrhage (ICH), and 3 patients (4.2%) experienced asymptomatic ICH. There were no postimplantation infections or other postoperative complications associated with the SEEG. Several common complications related to resection surgery were included in this series with zero mortality. Of the 6 patients in whom we performed a second surgery, 4 of them subsequently became seizure-free (66.7%) after undergoing the second resection with SEEG evaluation. Stereoelectroencephalophraphy is a safe and efficient methodology to identify the EZ in particularly complex cases of focal medically refractory epilepsy for pediatric patients, even in infancy and early childhood. Seizure outcomes of SEEG-guided resection surgery are desirable. We recommend SEEG evaluations and even a more aggressive resection in certain pediatric patients who failed initial resection with realistic chances to benefit from reoperation.

Jean Talairach: a cerebral cartographer

Although French psychiatrist-turned-neurosurgeon Jean Talairach (1911-2007) is perhaps best known for the stereotaxic atlas he produced with Pierre Tournoux and Gábor Szikla, he has left his mark on most aspects of modern stereotactic and functional neurosurgery. In the field of psychosurgery, he expressed critique of the practice of prefrontal lobotomy and subsequently was the first to describe the more selective approach using stereotactic bilateral anterior capsulotomy. Turning his attention to stereotaxy, Talairach spearheaded the team at Hôpital Sainte-Anne in the construction of novel stereotaxic apparatus. Cadaveric investigation using these tools and methods resulted in the first human stereotaxic atlas where the use of the anterior and posterior commissures as intracranial reference points was established. This work revolutionized the approach to cerebral localization as well as leading to the development of numerous novel stereotactic interventions by the Sainte-Anne team, including tumor biopsy, interstitial irradiation, thermal ablation, and endonasal procedures. Together with epileptologist Jean Bancaud, Talairach invented the field of stereo-electroencephalography and developed a robust scientific methodology for the assessment and treatment of epilepsy. In this article the authors review Talairach's career trajectory in its historical context and in view of its impact on modern stereotactic and functional neurosurgery.

Surface-Based Registration of MR Scan versus Refined Anatomy-Based Registration of CT Scan: Effect on the Accuracy of SEEG Electrodes Implantation Performed in Prone Position under Frameless Neuronavigation

INTRODUCTION

Stereoelectroencephalography (SEEG) refers to a commonly used diagnostic procedure to localise and define the epileptogenic zone of refractory focal epilepsies, by means of minimally invasive operation techniques without large craniotomies.

OBJECTIVE

This study aimed to investigate the influence of different registration methods on the accuracy of SEEG electrode implantation under neuronavigation for paediatric patients with refractory epilepsy.

METHODS

The clinical data of 18 paediatric patients with refractory epilepsy were retrospectively analysed. The SEEG electrodes were implanted under optical neuronavigation while the patients were in the prone position. Patients were divided into two groups on the basis of the surface-based registration of MR scan method and refined anatomy-based registration of CT scan. Registration time, accuracy, and the differences between electrode placement and preoperative planned position were analysed.

RESULTS

Thirty-six electrodes in 7 patients were placed under surface-based registration of MR scan, and 45 electrodes in 11 patients were placed under refined anatomy-based registration of CT scan. The registration time of surface-based registration of MR scan and refined anatomy-based registration of CT scan was 45 ± 12 min and 10 ± 4 min. In addition, the mean registration error, the error of insertion point, and target error were 3.6 ± 0.7 mm, 2.7 ± 0.7 mm, and 3.1 ± 0.5 mm in the surface-based registration of MR scan group, and 1.1 ± 0.3 mm, 1.5 ± 0.5 mm, and 2.2 ± 0.6 mm in the refined anatomy-based registration of CT scan group. The differences between the two registration methods were statistically significant.

CONCLUSIONS

The refined anatomy-based registration of CT scan method can improve the registration efficiency and electrode placement accuracy, and thereby can be considered as the preferred registration method in the application of SEEG electrode implantation under neuronavigation for treatment of paediatric intractable epilepsy.

Robot-assisted versus manual navigated stereoelectroencephalography in adult medically-refractory epilepsy patients

OBJECTIVE

Stereoelectroencephalography (SEEG) has experienced a recent growth in adoption for epileptogenic zone (EZ) localization. Advances in robotics have the potential to improve the efficiency and safety of this intracranial seizure monitoring method. We present our institutional experience employing robot-assisted SEEG and compare its operative efficiency, seizure reduction outcomes, and direct hospital costs with SEEG performed without robotic assistance using navigated stereotaxy.

METHODS

We retrospectively identified 50 consecutive adult SEEG cases at our institution in this IRB-approved study, of which 25 were navigated with image guidance (hereafter referred to as "navigated") (02/2014-10/2016) and 25 were robot-assisted (09/2016-12/2017). A thorough review of medical/surgical history and operative records with imaging and trajectory plans was done for each patient. Direct inpatient costs related to each technique were compared.

RESULTS

Most common seizure etiologies for patients undergoing navigated and robot-assisted SEEG included non-lesional and benign temporal lesions. Despite having a higher mean number of leads-per-patient (10.2 ± 3.5 versus 7.2 ± 2.6, P = 0.002), robot-assisted cases had a significantly shorter mean operative time than navigated cases (125.5±48.5 versus 173.4±84.3 min, P = 0.02). Comparison of robot-assisted cases over the study interval revealed no significant difference in mean operative time (136.4±51.4 min for the first ten cases versus 109.9±75.8 min for the last ten cases, P = 0.25) and estimated operative time-per-lead (13.4±6.0 min for the first ten cases versus 12.9±7.7 min for the last ten cases, P = 0.86). The mean depth, radial, target, and entry point errors for robot-assisted cases were 2.12±1.89, 1.66±1.58, 3.05±2.02 mm, and 1.39 ± 0.75 mm, respectively. The two techniques resulted in equivalent EZ localization rate (navigated 88 %, robot-assisted 96 %, P = 0.30). Common types of epilepsy surgery performed consisted of implantation of responsive neurostimulation (RNS) device (56 %), resection (19.1 %), and laser ablation (23.8 %) for navigated SEEG. For robot-assisted SEEG, either RNS implantation (68.2 %) or laser ablation (22.7 %) were performed or offered. A majority of navigated and robot-assisted patients who underwent epilepsy surgery achieved either Engel Class I (navigated 36.8 %, robot-assisted 31.6 %) or II (navigated 36.8 %, robot-assisted 15.8 %) outcome with no significant difference between the groups (P = 0.14). Direct hospital cost for robot-assisted SEEG was 10 % higher than non-robotic cases.

CONCLUSION

This single-institutional study suggests that robotic assistance can enhance efficiency of SEEG without compromising safety or precision when compared to image guidance only. Adoption of this technique with uniform safety and efficacy over a short period of time is feasible with favorable epilepsy outcomes.

Rigid Cranial Fixation for Robot-Assisted Stereoelectroencephalography in Toddlers: Technical Considerations

BACKGROUND

Stereoelectroencephalography (sEEG) using depth electrodes has become a mainstay of pediatric epilepsy surgery. This technique relies on rigid cranial fixation using skull pins, which forms the basis for accurate stereotactic navigation. The use of cranial fixation pins poses the threat of traumatic skull injuries in young children because of inadequate cranial bone thickness.

OBJECTIVE

To describe a rigid cranial fixation technique involving the integrated Gel Head Ring from the DORO QR3 multipurpose skull clamp set (Pro Med Instruments) with superimposed pin fixation in children below the age of 36 mo undergoing sEEG.

METHODS

Patients were placed in the supine position and the head was fixed using a DORO skull clamp with 3 pediatric cranial pins. The head was supported on the integrated Gel Head Ring, and a pin pressure of 20 pounds was applied. The DORO skull clamp set was then attached to the ROSA neurosurgical robot support telescopic arm for stereotactic navigation.

RESULTS

We present an illustrative series of 2 patients below the age of 3 yr with medically refractory epilepsy who underwent sEEG using our modified cranial fixation technique. Head position and reference registration were stable throughout the surgeries. Postoperative volumetric computed tomography scans of the head showed accurate placement of sEEG depth electrodes and did not reveal any fractures or epidural hematoma. No other complications related to cranial fixation were noted.

CONCLUSION

Concurrent use of rigid and nonrigid cranial fixation using the DORO skull clamp set provides safe and effective cranial fixation in infants and toddlers undergoing sEEG.

Stereoelectroencephalography in Pediatric Epilepsy Surgery

Stereoelectroencephalography (SEEG) is an invasive technique used during the surgical management of medically refractory epilepsy. The utility of SEEG rests in its ability to survey the three-dimensional organization of the epileptogenic zone as well as nearby eloquent cortices. Once concentrated to specialized centers in Europe and Canada, the SEEG methodology has gained worldwide popularity due to its favorable morbidity profile, superior coverage of deep structures, and ability to perform multilobar explorations without the need for craniotomy. This rapid shift in practice represents both a challenge and an opportunity for pediatric neurosurgeons familiar with the subdural grid approach. The purpose of this review is to discuss the indications, technique, and safety of long-term SEEG monitoring in children. In addition to reviewing the conceptual and technical points of the diagnostic evaluation, attention will also be given to SEEG-based interventions (e.g., radiofrequency thermo-coagulation).