Dose prescription for stereotactic body radiotherapy: general and organ-specific consensus statement from the DEGRO/DGMP Working Group Stereotactic Radiotherapy and Radiosurgery.

PURPOSE AND OBJECTIVE: To develop expert consensus statements on multiparametric dose prescriptions for stereotactic body radiotherapy (SBRT) aligning with ICRU report 91. These statements serve as a foundational step towards harmonizing current SBRT practices and refining dose prescription and documentation requirements for clinical trial designs. MATERIALS AND METHODS: Based on the results of a literature review by the working group, a two-tier Delphi consensus process was conducted among 24 physicians and physics experts from three European countries. The degree of consensus was predefined for overarching (OA) and organ-specific (OS) statements (≥ 80%, 60-79%, < 60% for high, intermediate, and poor consensus, respectively). Post-first round statements were refined in a live discussion for the second round of the Delphi process. RESULTS: Experts consented on a total of 14 OA and 17 OS statements regarding SBRT of primary and secondary lung, liver, pancreatic, adrenal, and kidney tumors regarding dose prescription, target coverage, and organ at risk dose limitations. Degree of consent was ≥ 80% in 79% and 41% of OA and OS statements, respectively, with higher consensus for lung compared to the upper abdomen. In round 2, the degree of consent was ≥ 80 to 100% for OA and 88% in OS statements. No consensus was reached for dose escalation to liver metastases after chemotherapy (47%) or single-fraction SBRT for kidney primaries (13%). In round 2, no statement had 60-79% consensus. CONCLUSION: In 29 of 31 statements a high consensus was achieved after a two-tier Delphi process and one statement (kidney) was clearly refused. The Delphi process was able to achieve a high degree of consensus for SBRT dose prescription. In summary, clear recommendations for both OA and OS could be defined. This contributes significantly to harmonization of SBRT practice and facilitates dose prescription and reporting in clinical trials investigating SBRT.

Lumbar Spinous Process-Splitting Technique for Ligamentum Flavum Cyst Removal.

BACKGROUND: Laminotomy for lumbar stenosis is a well-defined procedure and represents a routine in every neurosurgical department. It is a common experience that the uni- or bilateral paraspinal muscle detachment, together with injury of the supra- and interspinous ligaments, can lead to postoperative pain. In the literature, the application of a minimally invasive technique, the lumbar spinous process-splitting (LSPS) technique, has been reported. METHODS: In this study, we present a case series of 12 patients who underwent LSPS from September 2019 to April 2020. Two patients had a cyst of the ligamentum flavum, eight a single-level lumbar canal stenosis (LCS), and two a two-level LCS. Moreover, we propose a novel morphological classification of postoperative muscle atrophy and present volumetric analysis of the decompression achieved. RESULTS: There were no complications related to this technique. In all patients, the vertebral canal area was more than doubled by the procedure. The muscle sparing showed grade A, according to our classification. CONCLUSION: To our knowledge, this is the first description of this surgical technique and the first LSPSL case series in Europe. Furthermore, cases of ligamentum flavum cyst removal using this safe and effective technique have not yet been reported.

Randomized Clinical Trials and Observational Tribulations: Providing Clinical Evidence for Personalized Surgical Pain Management Care Models.

Proving clinical superiority of personalized care models in interventional and surgical pain management is challenging. The apparent difficulties may arise from the inability to standardize complex surgical procedures that often involve multiple steps. Ensuring the surgery is performed the same way every time is nearly impossible. Confounding factors, such as the variability of the patient population and selection bias regarding comorbidities and anatomical variations are also difficult to control for. Small sample sizes in study groups comparing iterations of a surgical protocol may amplify bias. It is essentially impossible to conceal the surgical treatment from the surgeon and the operating team. Restrictive inclusion and exclusion criteria may distort the study population to no longer reflect patients seen in daily practice. Hindsight bias is introduced by the inability to effectively blind patient group allocation, which affects clinical result interpretation, particularly if the outcome is already known to the investigators when the outcome analysis is performed (often a long time after the intervention). Randomization is equally problematic, as many patients want to avoid being randomly assigned to a study group, particularly if they perceive their surgeon to be unsure of which treatment will likely render the best clinical outcome for them. Ethical concerns may also exist if the study involves additional and unnecessary risks. Lastly, surgical trials are costly, especially if the tested interventions are complex and require long-term follow-up to assess their benefit. Traditional clinical testing of personalized surgical pain management treatments may be more challenging because individualized solutions tailored to each patient's pain generator can vary extensively. However, high-grade evidence is needed to prompt a protocol change and break with traditional image-based criteria for treatment. In this article, the authors review issues in surgical trials and offer practical solutions.

The Changing Environment in Postgraduate Education in Orthopedic Surgery and Neurosurgery and Its Impact on Technology-Driven Targeted Interventional and Surgical Pain Management: Perspectives from Europe, Latin America, Asia, and The United States.

Personalized care models are dominating modern medicine. These models are rooted in teaching future physicians the skill set to keep up with innovation. In orthopedic surgery and neurosurgery, education is increasingly influenced by augmented reality, simulation, navigation, robotics, and in some cases, artificial intelligence. The postpandemic learning environment has also changed, emphasizing online learning and skill- and competency-based teaching models incorporating clinical and bench-top research. Attempts to improve work-life balance and minimize physician burnout have led to work-hour restrictions in postgraduate training programs. These restrictions have made it particularly challenging for orthopedic and neurosurgery residents to acquire the knowledge and skill set to meet the requirements for certification. The fast-paced flow of information and the rapid implementation of innovation require higher efficiencies in the modern postgraduate training environment. However, what is taught typically lags several years behind. Examples include minimally invasive tissue-sparing techniques through tubular small-bladed retractor systems, robotic and navigation, endoscopic, patient-specific implants made possible by advances in imaging technology and 3D printing, and regenerative strategies. Currently, the traditional roles of mentee and mentor are being redefined. The future orthopedic surgeons and neurosurgeons involved in personalized surgical pain management will need to be versed in several disciplines ranging from bioengineering, basic research, computer, social and health sciences, clinical study, trial design, public health policy development, and economic accountability. Solutions to the fast-paced innovation cycle in orthopedic surgery and neurosurgery include adaptive learning skills to seize opportunities for innovation with execution and implementation by facilitating translational research and clinical program development across traditional boundaries between clinical and nonclinical specialties. Preparing the future generation of surgeons to have the aptitude to keep up with the rapid technological advances is challenging for postgraduate residency programs and accreditation agencies. However, implementing clinical protocol change when the entrepreneur-investigator surgeon substantiates it with high-grade clinical evidence is at the heart of personalized surgical pain management.

The projected numbers of degenerative spine disease in Austria from 2017 to 2080: a perspective-based scenario analysis.

BACKGROUND: Spinal surgery has to address the challenge of a dramatic increase of the growing number of older persons. The purpose of the present study was to project the numbers of surgically treated degenerative spine disease (DSD) in Austria from 2017 until 2080 to provide potential future scenarios that the Austrian Health system might have to face. METHODS: Current numbers on demographic information from Austria as well as population projections for 2017-2080 were obtained from Statistics Austria (STAT). A lower/main/upper scenario reflecting low/main/high growth and ageing scenarios deducted from fertility, life expectancy and immigration calculations was used. Information on prevalence of surgically treated DSD was obtained from the Austrian Spine Register. RESULTS: The population in Austria (evaluated in 2017) was 8.78 millions and is estimated to evolve to 7.86/10.0/13.1 millions by 2080. The total number of surgically treated DSD recorded in the Spine Register was 9300 and was estimated to be 9300/11200/13700 in 2080. The number of subjects with surgically treated DSD were expected to increase in the age-strata (main scenario), 100% corresponds to the number in each age and gender stratum: 0-40 years by (male/female) 2%/2%, 40-50 years -7%/-7%, 50-59 years -11%/-9%, 60-69 years 21%/16%, 70-79 years 51%/31%, 80-89 years 211%/129% and 90+years 698%/411%. CONCLUSIONS: Total numbers of subjects with DSD in Austria will increase from 2017 to 2080. The increase will be substantial in those aged 80+ and those aged 90+. The assumptions of this analysis were taken conservatively. Hence, the future socio-economic burden to society might be greater as projected by the study.

Optic Tract as an Upper Limit in Amygdalectomy: Microsurgical Study.

BACKGROUND: In surgeries involving resection of the amygdala, despite clear relations established with the medial, lateral, anterior, posterior, and inferior segments, the upper limit remains controversial. The optic tract (OT) has been anatomically considered as a good landmark immediately inferior to the striatopallidal region. This anatomic structure has barely been explored by microsurgical study, generating uncertainty about the exact relationship with the surrounding structures. OBJECTIVE: To describe the OT in its entire length through microsurgical study, showing its superior, inferior, medial, and lateral relationships and highlighting its value as a landmark in superior amygdala resection. METHODS: Microsurgical anatomic dissection of the OT, from its origin in the chiasm to the lateral geniculate nucleus was performed in 8 alcohol-fixed human hemispheres, showing its different segments and relations. Photographs were taken from different angles to facilitate surgical orientation. RESULTS: We performed a dissection of the OT, showing its position relative to caudate and hippocampal formations. We exposed the structures related to the OT superiorly (striatopallidal region and superior caudate fasciculus), inferiorly (head of the hippocampus, amygdala, anterior choroidal artery, perforating artery branch of the anterior choroidal artery, terminal stria, and basal vein), medially (internal capsule and midbrain), and laterally (temporal stem [uncinate and inferior fronto-occipital fascicle], anterior perforated substance, and superior caudate fasciculus). CONCLUSION: To date, there is a paucity of articles describing the anatomy of the OT from a neurosurgery perspective. In this study, we describe the microsurgical anatomic path of the OT, as a reliable upper limit landmark for amygdala resection.

Intracranial Venous Alteration in Patients With Aneurysmal Subarachnoid Hemorrhage: Protocol for the Prospective and Observational SAH Multicenter Study (SMS).

Background: Arterial vasospasm has been ascribed as the responsible etiology of delayed cerebral infarction in patients with aneurysmal subarachnoid hemorrhage (aSAH), but other neurovascular structures may be involved. We present the protocol for a multicenter, prospective, observational study focused on analyzing morphological changes in cerebral veins of patients with aSAH. Methods and Analysis: In a retrospective arm, we will collect head arterial and venous CT angiograms (CTA) of 50 patients with aSAH and 50 matching healthy controls at days 0-2 and 7-10, comparing morphological venous changes. A multicenter prospective observational study will follow. Patients aged ≥18 years of any gender with aSAH will be enrolled at 9 participating centers based on the predetermined eligibility criteria. A sample size of 52 aSAH patients is expected, and 52 healthy controls matched per age, gender, and comorbidities will be identified. For each patient, sequential CTA will be conducted upon admission (day 0-2), at 7-10 days, and at 14-21 days after aSAH, evaluating volumes and morphology of the cerebral deep veins and main cortical veins. One specialized image collecting center will analyze all anonymized CTA scans, performing volumetric calculation of targeted veins. Morphological venous changes over time will be evaluated using the Dice coefficient and the Jaccard index and scored using the Boeckh-Behrens system. Morphological venous changes will be correlated to clinical outcomes and compared between patients with aSAH and healthy-controls, and among groups based on surgical/endovascular treatments for aSAH. Ethics and Dissemination: This protocol has been approved by the ethics committee and institutional review board of Ethikkommission, SALK, Salzburg, Austria, and will be approved at all participating sites. The study will comply with the Declaration of Helsinki. Written informed consent will be obtained from all enrolled patients or their legal tutors. We will present our findings at academic conferences and peer-reviewed journals. Approved Protocol Version and Registration: Version 2, 09 June 2021.

The "springform" technique in cranioplasty: custom made 3D-printed templates for intraoperative modelling of polymethylmethacrylate cranial implants.

BACKGROUND: Manual moulding of cranioplasty implants after craniectomy is feasible, but does not always yield satisfying cosmetic results. In contrast, 3D printing can provide precise templates for intraoperative moulding of polymethylmethacrylate (PMMA) implants in cranioplasty. Here, we present a novel and easily implementable 3D printing workflow to produce patient-specific, sterilisable templates for PMMA implant moulding in cranioplastic neurosurgery. METHODS: 3D printable templates of patients with large skull defects before and after craniectomy were designed virtually from cranial CT scans. Both templates - a mould to reconstruct the outer skull shape and a ring representing the craniectomy defect margins - were printed on a desktop 3D printer with biocompatible photopolymer resins and sterilised after curing. Implant moulding and implantation were then performed intraoperatively using the templates. Clinical and radiological data were retrospectively analysed. RESULTS: Sixteen PMMA implants were performed on 14 consecutive patients within a time span of 10 months. The median defect size was 83.4 cm2 (range 57.8-120.1 cm2). Median age was 51 (range 21-80) years, and median operating time was 82.5 (range 52-152) min. No intraoperative complications occurred; PMMA moulding was uneventful and all implants fitted well into craniectomy defects. Excellent skull reconstruction could be confirmed in all postoperative computed tomography (CT) scans. In three (21.4%) patients with distinct risk factors for postoperative haematoma, revision surgery for epidural haematoma had to be performed. No surgery-related mortality or new and permanent neurologic deficits were recorded. CONCLUSION: Our novel 3D printing-aided moulding workflow for elective cranioplasty with patient-specific PMMA implants proved to be an easily implementable alternative to solely manual implant moulding. The "springform" principle, focusing on reconstruction of the precraniectomy skull shape and perfect closure of the craniectomy defect, was feasible and showed excellent cosmetic results. The proposed method combines the precision and cosmetic advantages of computer-aided design (CAD) implants with the cost-effectiveness of manually moulded PMMA implants.

Multilobar unilateral hypoplasia with emphasis on the posterior quadrant and severe epilepsy in children with FCD ILAE Type 1A.

OBJECTIVE: Focal cortical dysplasia (FCD) Type 1 and its three subtypes have yet not been fully characterized at the clinical, anatomopathological, and molecular level (International League Against Epilepsy [ILAE] FCD classification from 2011). We aimed to describe the clinical phenotype of patients with histopathologically confirmed FCD1A obtained from a single epilepsy center between 2002 and 2016. METHODS: Medical records were retrieved from the hospital's archive. Results from electroencephalography (EEG) video recordings, neuroimaging, and histopathology were reevaluated. Magnetic resonance imaging (MRI) post-processing was retrospectively performed in nine patients. DNA methylation studies were carried out from archival surgical brain tissue in 11 patients. RESULTS: Nineteen children with a histopathological diagnosis of FCD1A were included. The average onset of epilepsy was 0.9 years (range 0.2-10 years). All children had severe cognitive impairment and one third had mild motor deficits, yet fine finger movements were preserved in all patients. All patients had daily seizures, being drug resistant from disease onset. Interictal electroencephalography revealed bilateral multi-regional epileptiform discharges. Interictal status epilepticus was observed in 8 and countless subclinical seizures in 11 patients. Regional continuous irregular slow waves were of higher lateralizing and localizing yield than spikes. Posterior background rhythms were normal in 16 of 19 children. Neuroimaging showed unilateral multilobar hypoplasia and increased T2-FLAIR signals of the white matter in 18 of 19 patients. All children underwent tailored multilobar resections, with seizure freedom achieved in 47% (Engel class I). There was no case with frontal involvement without involvement of the posterior quadrant by MRI and histopathology. DNA methylation profiling distinguished FCD1A samples from all other epilepsy specimens and controls. SIGNIFICANCE: We identified a cohort of young children with drug resistance from seizure onset, bad EEG with posterior emphasis, lack of any focal neurological deficits but severe cognitive impairment, subtle hypoplasia of the epileptogenic area on MRI, and histopathologically defined and molecularly confirmed by DNA methylation analysis as FCD ILAE Type 1A.

A Review of Remote Intracerebral Hemorrhage after Chronic Subdural Hematoma Evacuation.

BACKGROUND: Remote intracerebral hemorrhage (RICH) is a severe complication following chronic subdural hematoma (cSDH) drainage, and only case reports and small case series have been reported to date. The authors present an emblematic patient affected by RICH following cSDH drainage. A systematic review of the literature on diagnosis and management of patients affected by RICH following cSDH evacuation has also been performed. METHODS: A literature search according to the PRISMA statement was conducted using PubMed and Scopus databases with the following Mesh terms: [(remote) AND (intracerebral hemorrhage or cerebral hematoma or cerebral infarction or cerebellar hemorrhage or cerebellar hematoma or cerebellar infarction) AND (chronic subdural hematoma)]. RESULTS: The literature search yielded 35 results, and 25 articles met our inclusion criteria: 22 articles were case reports and 3 were case series including three to six patients. Overall, 37 patients were included in the study. Age was reported in all 37 patients, 26 males (70.3%) and 11 females (29.7%), with a male-to-female ratio of 2.4:1. The mean age at diagnosis was 64.6 years (range: 0.25-86 years). Only in 5 cases (13.5%) did the ICH occur contralaterally to the previously drained cSDH. The rapidity of drainage can lead to several types of intracranial hemorrhages, caused by a too rapid change in the cerebral blood flow (CBF) and/or tears of bridging veins. The average time interval between cSDH drainage and neurologic deterioration was 71.05 hours (range: 0-192 hours). CONCLUSIONS: RICH following cSDH represents a rare occurrence and a serious complication, associated with elevated morbidity. Careful monitoring of drain speed after cSDH evacuation surgery is recommended, and minimally invasive techniques such as twist drill craniostomy are suggested, especially for massive cSDHs.

Genotypical glioblastoma of the frontal lobe mimicking ganglioglioma: A case report and review of the literature.

This case of severe phenotype-genotype mismatch brain tumor morphologically mimicking benign ganglioglioma emphasizes the urgent need for advanced molecular profiling in brain tumor diagnosis in the era of sophisticated molecular profiling.

Perforating Arteries of the Lemniscal Trigone: A Microsurgical Neuroanatomic Description.

Background: The perforating arteries in the dorsolateral zone of the midbrain play a crucial role in the functions of the brain stem. Their damage due to herniation, pathological lesions, or surgery, favored by the narrow tentorial incisura, can lead to hemorrhages or ischemia and subsequently to severe consequences for the patient. Objective: In literature, not much attention has been directed to the perforating arteries in the lemniscus; in fact, no reports on the perforators of this anatomical region are available. The present study aims to a detailed analysis of the microanatomy and the clinical implications of these perforators, in relation to the parent vessels. We focused on the small vessels that penetrate the midbrain's dorsolateral surface, known as lemniscal trigone, to understand better their microanatomy and their functional importance in the clinical practice during the microsurgical approach to this area. Methods: Eighty-seven alcohol-fixed cadaveric hemispheres (44 brains) without any pathological lesions provided the material for studying the perforating vessels and their origin around the dorsolateral midbrain using an operating microscope (OPMI 1 FC, Zeiss). Measurements of the perforators' distances, in relation to the parent vessels, were taken using a digital caliper. Results: An origin from the SCA could be found in 70.11% (61) and from the PCA in 27.58% (24) of the hemispheres. In one hemisphere, an origin from the posterior choroidal artery was found (4.54%). No perforating branches were discovered in 8.04% of specimens (7). Conclusion: The perforating arteries of the lemniscal trigone stem not only from the superior cerebellar artery (SCA), as described in the few studies available in literature, but also from the posterior cerebral artery (PCA). Therefore, special attention should be paid during surgery to spare those vessels and associated perforators. A comprehensive understanding of the lemniscal trigone's perforating arteries is vital to avoid infarction of the brainstem when treating midbrain tumors or vascular malformations.

Integrated analysis of programmed cell death ligand 1 expression reveals increased levels in high-grade glioma.

PURPOSE: Gliomas are the most frequent primary brain tumors of adults. Despite intensive research, there are still no targeted therapies available. Here, we performed an integrated analysis of glioma and programmed cell death ligand 1 (PD-L1) in 90 samples including 58 glioma and 32 control brain tissues. METHODS: To identify PD-L1 expression in glioma, we performed immunohistochemical analysis of PD-L1 tumor proportion score (TPS) using the clinically valid PD-L1 22C3 antibody on 90 samples including controls and WHO grade I-IV gliomas. RESULTS: We found that PD-L1 is highly expressed in a subfraction of glioma cells. Analysis of PD-L1 levels in different glioma subtypes revealed a strong intertumoral variation of PD-L1 protein. Furthermore, we correlated PD-L1 expression with molecular glioma hallmarks such as MGMT-promoter methylation, IDH1/2 mutations, TERT promoter mutations and LOH1p/19q. CONCLUSION: In summary, we found that PD-L1 is highly expressed in a subfraction of glioma, indicating PD-L1 as a potential new marker in glioma assessment opening up novel therapeutic approaches.

Structural Damage Identification of Composite Rotors Based on Fully Connected Neural Networks and Convolutional Neural Networks.

Damage identification of composite structures is a major ongoing challenge for a secure operational life-cycle due to the complex, gradual damage behaviour of composite materials. Especially for composite rotors in aero-engines and wind-turbines, a cost-intensive maintenance service has to be performed in order to avoid critical failure. A major advantage of composite structures is that they are able to safely operate after damage initiation and under ongoing damage propagation. Therefore, a robust, efficient diagnostic damage identification method would allow monitoring the damage process with intervention occurring only when necessary. This study investigates the structural vibration response of composite rotors by applying machine learning methods and the ability to identify, localise and quantify the present damage. To this end, multiple fully connected neural networks and convolutional neural networks were trained on vibration response spectra from damaged composite rotors with barely visible damage, mostly matrix cracks and local delaminations using dimensionality reduction and data augmentation. A databank containing 720 simulated test cases with different damage states is used as a basis for the generation of multiple data sets. The trained models are tested using k-fold cross validation and they are evaluated based on the sensitivity, specificity and accuracy. Convolutional neural networks perform slightly better providing a performance accuracy of up to 99.3% for the damage localisation and quantification.

Trends and outcomes for non-elective neurosurgical procedures in Central Europe during the COVID-19 pandemic.

The world currently faces the novel severe acute respiratory syndrome coronavirus 2 pandemic. Little is known about the effects of a pandemic on non-elective neurosurgical practices, which have continued under modified conditions to reduce the spread of COVID-19. This knowledge might be critical for the ongoing second coronavirus wave and potential restrictions on health care. We aimed to determine the incidence and 30-day mortality rate of various non-elective neurosurgical procedures during the COVID-19 pandemic. A retrospective, multi-centre observational cohort study among neurosurgical centres within Austria, the Czech Republic, and Switzerland was performed. Incidence of neurosurgical emergencies and related 30-day mortality rates were determined for a period reflecting the peak pandemic of the first wave in all participating countries (i.e. March 16th-April 15th, 2020), and compared to the same period in prior years (2017, 2018, and 2019). A total of 4,752 emergency neurosurgical cases were reviewed over a 4-year period. In 2020, during the COVID-19 pandemic, there was a general decline in the incidence of non-elective neurosurgical cases, which was driven by a reduced number of traumatic brain injuries, spine conditions, and chronic subdural hematomas. Thirty-day mortality did not significantly increase overall or for any of the conditions examined during the peak of the pandemic. The neurosurgical community in these three European countries observed a decrease in the incidence of some neurosurgical emergencies with 30-day mortality rates comparable to previous years (2017-2019). Lower incidence of neurosurgical cases is likely related to restrictions placed on mobility within countries, but may also involve delayed patient presentation.

VarioGuide® frameless neuronavigation-guided stereoelectroencephalography in adult epilepsy patients: technique, accuracy and clinical experience.

BACKGROUND: Stereoelectroencephalography (SEEG) allows the identification of deep-seated seizure foci and determination of the epileptogenic zone (EZ) in drug-resistant epilepsy (DRE) patients. We evaluated the accuracy and treatment-associated morbidity of frameless VarioGuide® (VG) neuronavigation-guided depth electrode (DE) implantations. METHODS: We retrospectively identified all consecutive adult DRE patients, who underwent VG-neuronavigation DE implantations, between March 2013 and April 2019. Clinical data were extracted from the electronic patient charts. An interdisciplinary team agreed upon all treatment decisions. We performed trajectory planning with iPlan® Cranial software and DE implantations with the VG system. Each electrode's accuracy was assessed at the entry (EP), the centre (CP) and the target point (TP). We conducted correlation analyses to identify factors associated with accuracy. RESULTS: The study population comprised 17 patients (10 women) with a median age of 32.0 years (range 21.0-54.0). In total, 220 DEs (median length 49.3 mm, range 25.1-93.8) were implanted in 21 SEEG procedures (range 3-16 DEs/surgery). Adequate signals for postoperative SEEG were detected for all but one implanted DEs (99.5%); in 15/17 (88.2%) patients, the EZ was identified and 8/17 (47.1%) eventually underwent focus resection. The mean deviations were 3.2 ± 2.4 mm for EP, 3.0 ± 2.2 mm for CP and 2.7 ± 2.0 mm for TP. One patient suffered from postoperative SEEG-associated morbidity (i.e. conservatively treated delayed bacterial meningitis). No mortality or new neurological deficits were recorded. CONCLUSIONS: The accuracy of VG-SEEG proved sufficient to identify EZ in DRE patients and associated with a good risk-profile. It is a viable and safe alternative to frame-based or robotic systems.