Publications by authors named "Karl Schaller"

255 Publications

Neuropsychological Outcomes after Surgery for Olfactory Groove Meningiomas.

Cancers (Basel) 2021 May 21;13(11). Epub 2021 May 21.

Department of Clinical Neurosciences, Division of Neurosurgery, Geneva University Hospitals, 1205 Geneva, Switzerland.

Background: In recent years, several studies have reported abnormal pre- and postoperative neuropsychological functioning in patients with meningiomas located in the prefrontal cortex (notably the ventromedial region). In the case of olfactory groove meningiomas, the tumor is in direct contact with the inferior aspect of the prefrontal cortex, a cortical region with crucial roles in decision-making, cognition and memory functions, potentially negatively impacting neuropsychological functions.

Materials And Methods: We retrospectively compared pre- and post-operative neuropsychological testing of 17 patients undergoing surgical removal of olfactory groove meningiomas in our institution between January 2013 and December 2018. Neuropsychological results were obtained from the patients' medical history and normalized as z-scores of their respective cognitive functions.

Results: Assessment of cognitive follow-up showed an important heterogeneity among patients. Pre-operative cognitive impairment was observed in most patients, particularly in cognitive flexibility (mean z-score: -1.35). Immediate post-operative cognitive status showed an overall impairment in all domains of cognition, significant for the domains of attention ( = 0.0273) and flexibility ( = 0.0234) and almost significant for the domain of language ( = 0.0547). The late follow-up at one year showed a trend towards general improvement, although attention and flexibility remained impaired.

Discussion: Olfactory groove meningiomas impact pre-frontal cortex cognitive functions, particularly in the domain of cognitive flexibility. After an initial postoperative worsening, patients tended to improve in most aspects after one year, aside from cognitive flexibility and attention.
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http://dx.doi.org/10.3390/cancers13112520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8196649PMC
May 2021

Intraoperative subcortico-cortical evoked potentials of the visual pathway under general anesthesia.

Clin Neurophysiol 2021 Jul 9;132(7):1381-1388. Epub 2021 Apr 9.

Faculty of Medicine, University of Geneva, Geneva, Switzerland; Departement of Neurosurgery, Geneva University Hospitals, Geneva, Switzerland.

Objective: To assess whether intraoperative subcortical mapping of the visual pathways during brain surgeries was feasible.

Methods: Subcortico-cortical evoked potentials (SCEPs: 30 stimulations/site, biphasic single pulse, 1.3 Hz, 0.2 ms/phase, maximum 10 mA; bipolar probe) were measured in 12 patients for stimulation of the optic radiation, Meyer's loop or optic nerve. Recorded sites were bilateral central, parietal, parieto-occipital, occipital (subdermal scalp electrodes, 5-4000 Hz). The minimum distances from the stimulation locations, i.e. the closest border of the resection cavity to the diffusion tensor imaging based visual pathways, were evaluated postoperatively (smallest distance across coronal, sagittal and axial planes).

Results: Stimulation elicited SCEPs when the visual tracts were close (≤4.5 mm). The responses consisted of a short (P1, 3.0-5.6 ms; 8/8 patients) and of a middle (P2, 15-21.6 ms; 3/8 patients) latency waveforms. In agreement with the neuroanatomy, ipsilateral occipital responses were obtained for temporal or parietal stimulations, and bi-occipital responses for optic nerve stimulations.

Conclusions: For the first time to our knowledge, intraoperative SCEPs were observed for stimulations of the optic radiation and of Meyer's loop. Short latency responses were found in agreement with fast conduction of the visual pathway's connecting myelinated fibers.

Significance: The mapping of the visual pathways was found feasible for neurosurgeries under general anesthesia.
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http://dx.doi.org/10.1016/j.clinph.2021.02.399DOI Listing
July 2021

MRI-Compatible and Conformal Electrocorticography Grids for Translational Research.

Adv Sci (Weinh) 2021 05 8;8(9):2003761. Epub 2021 Mar 8.

Bertarelli Foundation Chair in Neuroprosthetic Technology Laboratory for Soft Bioelectronic Interfaces Institute of Microengineering Institute of Bioengineering Center for Neuroprosthetics Ecole Polytechnique Fédérale de Lausanne (EPFL) Geneva 1202 Switzerland.

Intraoperative electrocorticography (ECoG) captures neural information from the surface of the cerebral cortex during surgeries such as resections for intractable epilepsy and tumors. Current clinical ECoG grids come in evenly spaced, millimeter-sized electrodes embedded in silicone rubber. Their mechanical rigidity and fixed electrode spatial resolution are common shortcomings reported by the surgical teams. Here, advances in soft neurotechnology are leveraged to manufacture conformable subdural, thin-film ECoG grids, and evaluate their suitability for translational research. Soft grids with 0.2 to 10 mm electrode pitch and diameter are embedded in 150 µm silicone membranes. The soft grids are compatible with surgical handling and can be folded to safely interface hidden cerebral surface such as the Sylvian fold in human cadaveric models. It is found that the thin-film conductor grids do not generate diagnostic-impeding imaging artefacts (<1 mm) nor adverse local heating within a standard 3T clinical magnetic resonance imaging scanner. Next, the ability of the soft grids to record subdural neural activity in minipigs acutely and two weeks postimplantation is validated. Taken together, these results suggest a promising future alternative to current stiff electrodes and may enable the future adoption of soft ECoG grids in translational research and ultimately in clinical settings.
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http://dx.doi.org/10.1002/advs.202003761DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8097365PMC
May 2021

Single-hole, ruptured parenchymal arteriovenous fistula of the mesencephalon: not known vascular malformation of the brain or a posthemorrhagic entity?

Ideggyogy Sz 2021 Mar;74(3-4):126-128

Neuroradiology Division, Department of Radiology and Medical Informatics, Geneva University Hospitals, Geneva, Switzerland.

The subtypes of brain arteriovenous malformations, with direct, single-hole fistulas without co-existing nidus are not described as existing entities inside the brain parenchyma but on the pial surface. True parenchymal arteriovenous malformations present with nidal structure, even if they are small, whereas surface lesions may present a direct fistulous configuration. In this case of midbrain haemorrhage a direct arteriovenous fistula was detected at the level of the red nucleus between a paramedian midbrain perforator artery and a paramedian parenchymal vein, with pseudo-aneurysm formation at the fistulous connection, without signs of adjacent nidus structure. The hypothesis whether a pre-existing arteriovenous fistula ruptured or a spontaneous haemorrhage has caused the fistulous connection is discussed.
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http://dx.doi.org/10.18071/isz.74.0126DOI Listing
March 2021

Surgical management of spinal metastases involving the cervicothoracic junction: results of a multicenter, European observational study.

Neurosurg Focus 2021 May;50(5):E7

2Department of Neurosurgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich.

Objective: Surgical management of spinal metastases at the cervicothoracic junction (CTJ) is highly complex and relies on case-based decision-making. The aim of this multicentric study was to describe surgical procedures for metastases at the CTJ and provide guidance for clinical and surgical management.

Methods: Patients eligible for this study were those with metastases at the CTJ (C7-T2) who had been consecutively treated in 2005-2019 at 7 academic institutions across Europe. The Spine Instability Neoplastic Score, neurological function, clinical status, medical history, and surgical data for each patient were retrospectively assessed. Patients were divided into four surgical groups: 1) posterior decompression only, 2) posterior decompression and fusion, 3) anterior corpectomy and fusion, and 4) anterior corpectomy and 360° fusion. Endpoints were complications, surgical revision rate, and survival.

Results: Among the 238 patients eligible for inclusion this study, 37 were included in group 1 (15%), 127 in group 2 (53%), 18 in group 3 (8%), and 56 in group 4 (24%). Mechanical pain was the predominant symptom (79%, 189 patients). Surgical complications occurred in 16% (group 1), 20% (group 2), 11% (group 3), and 18% (group 4). Of these, hardware failure (HwF) occurred in 18% and led to surgical revision in 7 of 8 cases. The overall complication rate was 34%. In-hospital mortality was 5%.

Conclusions: Posterior fusion and decompression was the most frequently used technique. Care should be taken to choose instrumentation techniques that offer the highest possible biomechanical load-bearing capacity to avoid HwF. Since the overall complication rate is high, the prevention of in-hospital complications seems crucial to reduce in-hospital mortality.
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http://dx.doi.org/10.3171/2021.2.FOCUS201067DOI Listing
May 2021

Meningiomas and Cognitive Impairment after Treatment: A Systematic and Narrative Review.

Cancers (Basel) 2021 Apr 13;13(8). Epub 2021 Apr 13.

Neurosurgical Division, Department of Neurosciences, Geneva University Hospitals, 1206 Geneva, Switzerland.

Clinical outcomes after surgery for intracranial meningiomas might be overvalued as cognitive dimensions and quality of life are probably underreported. This review aims to summarize the current state of cognitive screening and treatment-related outcomes after meningioma surgery. We present a systematic review (Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA-P) 2015-based) of cognitive outcomes after intracranial meningioma surgery. A total of 1572 patients (range 9-261) with a mean age of 58.4 years (range 23-87), and predominantly female ( = 1084, 68.9%) were identified. Mean follow-up time after treatment was 0.86 ± 0.3 years. Neuropsychological assessment was very heterogeneous, but five dimensions of cognition were described: memory (19/22); attention (18/22); executive functions (17/22); language (11/22); flexibility (11/22 studies). Cognitive abilities were impaired in 18 studies (81.8%), but only 1 showed deterioration in all dimensions simultaneously. Memory was the most affected. with significant post-therapy impairment in 9 studies (40.9%). Postoperatively, only 4 studies (18.2%) showed improvement in at least one dimension. Meningioma patients had significantly lower cognitive scores when compared to healthy subjects. Surgery and radiotherapy for meningiomas were associated with cognitive impairment, probably followed by a partial recovery. Cognition is poorly defined, and the assessment tools employed lack standardization. Cognitive impairment is probably underreported in meningioma patients.
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http://dx.doi.org/10.3390/cancers13081846DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8070481PMC
April 2021

Safety of Nitrous Oxide Anesthesia in a Selected Group of Patients Undergoing Neurosurgery: An Exploratory Subgroup Analysis of the ENIGMA Trials.

J Neurosurg Anesthesiol 2021 Apr 23. Epub 2021 Apr 23.

Department of Neurosurgery, Yale University School of Medicine, New Haven, CT Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH Departments of Neurosurgery Anesthesia, Geneva University Hospitals, Geneva, Switzerland Department of Anesthesiology and Perioperative Medicine, Alfred Hospital and Monash University Department of Anesthesia and Pain Medicine, Royal Melbourne Hospital, and Centre for Integrated Critical Care Medicine, University of Melbourne, Melbourne, Vic., Australia.

Background: The Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia (ENIGMA)-I and ENIGMA-II were randomized clinical trials that assessed the safety of nitrous oxide anesthesia in patients undergoing noncardiac surgery. In this study, we performed an exploratory pooled analysis of both ENIGMA trials to assess the safety of nitrous oxide in a selected group of patients undergoing neurosurgery.

Methods: Data from each ENIGMA trial were collated into a single database. Information regarding patient demographics, comorbidities, medication use, anesthesia, surgical procedure, and postoperative complications was extracted. Multivariate logistic regression was conducted for postoperative complications to assess the risk associated with nitrous oxide.

Results: A total of 830 patients were included in our analysis: 417 received nitrous oxide anesthesia, and 413 received nitrous oxide-free anesthesia. Baseline patient and perioperative characteristics were comparable. Procedural data were available for 535 patients (64%); of these, 507 (95%) underwent spinal neurosurgery and 28 (5%) underwent cranial neurosurgery. Patients in the nitrous oxide group had lower inspired oxygen concentration (30% vs. 38%; P<0.001) and end-tidal volatile agent concentration (0.56 vs. 0.89 minimal alveolar concentration equivalents; P<0.001) compared with the nitrous oxide-free group. Use of nitrous oxide was not associated with increased risk of postoperative complications (myocardial infarction, cardiac arrest, stroke, infection, severe vomiting, fever, pneumonia, pneumothorax, blood transfusion, venous thromboembolism, or death) (odds ratio: 1.22; 95% confidence interval: 0.89-1.65; P=0.22) or prolonged length of hospital stay (median 5.0 vs. 4.2 d for nitrous oxide and nitrous oxide-free groups; P=0.28).

Conclusion: Nitrous oxide did not increase the risk of postoperative complications or prolonged length of hospital stay in the neurosurgical cohort enrolled in the ENIGMA-I and ENIGMA-II trials.
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http://dx.doi.org/10.1097/ANA.0000000000000771DOI Listing
April 2021

Clonal Evolution of a High-Grade Pediatric Glioma With Distant Metastatic Spread.

Neurol Genet 2021 Apr 15;7(2):e561. Epub 2021 Feb 15.

Center for Translational Research in Onco-Hematology (E.M., V.D., P.-Y.D., P.T., D.M.), University of Geneva, Department of Oncology, Geneva University Hospital, Geneva and Swiss Cancer Center Léman (SCCL); Genetic Core Facility (S.N.), Geneva University Hospital; Diagnostic Department, Neuroradiology Division, (M.-I.V.), Neurosurgery Service (K.S.), and Department of Pathology (J.A.L.), Geneva University Hospital, Geneva, Switzerland.

Objective: High-grade glioma (HGG) rarely spreads outside the CNS. To test the hypothesis that the lesions were metastases originating from an HGG, we sequenced the relapsing HGG and distant extraneural lesions.

Methods: We performed whole-exome sequencing of an HGG lesion, its local relapse, and distant lesions in bone and lymph nodes.

Results: Phylogenetic reconstruction and histopathologic analysis confirmed the common glioma origin of the secondary lesions. The mutational profile revealed an IDH1/2 wild-type HGG with an activating mutation in and biallelic focal loss of (9p21). In the metastatic samples and the local relapse, we found an activating mutation, further copy number gains in chromosome 7 (), and a putative pathogenic driver mutation in a canonical splice site of

Conclusions: Our findings demonstrate tumor spread outside the CNS and identify potential genetic drivers of metastatic dissemination outside the CNS, which could be leveraged as therapeutic targets or potential biomarkers.
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http://dx.doi.org/10.1212/NXG.0000000000000561DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8063622PMC
April 2021

Occult Disco-Ligamentous Lesions of the Subaxial c-Spine-A Comparison of Preoperative Imaging Findings and Intraoperative Site Inspection.

Diagnostics (Basel) 2021 Mar 5;11(3). Epub 2021 Mar 5.

Department of Neurosurgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany.

Despite the general acceptance of magnetic resonance imaging (MRI) as the gold standard for diagnostics of traumatic disco-ligamentous injuries in the subaxial cervical spine, clinical experience shows cases where no lesion is detected in MRI exams but obtained during surgery. The aim of this study was to compare intraoperative site inspection to preoperative imaging findings and to identify radiological features of patients having a risk for under- or over-estimating disco-ligamentous lesions. We performed a retrospective analysis of our clinical database, considering all patients who underwent surgical treatment of the cervical spine via an anterior approach after trauma between June 2008 and April 2018. Only patients with availability of immediate preoperative computed tomography (CT), 3-Tesla MRI scans, and information about intraoperative findings were considered. Results of preoperative imaging were set in context to intraoperative findings, and receiver operator characteristics (ROC) were calculated. Out of 144 patients receiving anterior cervical surgery after trauma, 83 patients (mean age: 59.4 ± 20.5 years, age range: 12-94 years, 63.9% males) were included in this study. Included patients underwent surgical treatment via anterior cervical discectomy and fusion (ACDF; 79 patients) or anterior cervical corpectomy and fusion (4 patients) with ventral plating. Comparing preoperative imaging findings to intraoperative site inspection, a discrepancy between imaging and surgical findings was revealed in 14 patients, leading to an overall specificity/sensitivity of preoperative imaging to identify disco-ligamentous lesions of the cervical spine of 100%/77.4%. Yet, adding the existence of prevertebral hematoma and/or vertebral fractures according to preoperative imaging improved the sensitivity to 95.2%. Lack of sensitivity was most likely related to severe cervical spondylosis, rendering correct radiological reporting difficult. Thus, the risk of missing a traumatic disco-ligamentous injury of the cervical spine in imaging seems to be a particular threat in patients with preexisting degenerative cervical spondylosis. In conclusion, incorporating the existence of prevertebral hematoma and/or vertebral fractures can significantly improve diagnostic yield.
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http://dx.doi.org/10.3390/diagnostics11030447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998602PMC
March 2021

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

Sci Rep 2021 03 17;11(1):6171. Epub 2021 Mar 17.

Department of Neurosurgery, Ceske Budejovice Hospital, Ceske Budejovice, Czech Republic.

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.
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http://dx.doi.org/10.1038/s41598-021-85526-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969942PMC
March 2021

Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool.

Epilepsia 2021 May 13;62(5):1064-1073. Epub 2021 Mar 13.

Department of Pediatrics, BC Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.

Objective: To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy.

Methods: We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques.

Results: Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom.

Significance: Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making.
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http://dx.doi.org/10.1111/epi.16861DOI Listing
May 2021

The perspectives of mapping and monitoring of the sense of self in neurosurgical patients.

Acta Neurochir (Wien) 2021 05 8;163(5):1213-1226. Epub 2021 Mar 8.

Laboratory of Neurocognitive Science, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Geneva, Switzerland.

Surgical treatment of tumors, epileptic foci or of vascular origin, requires a detailed individual pre-surgical workup and intra-operative surveillance of brain functions to minimize the risk of post-surgical neurological deficits and decline of quality of life. Most attention is attributed to language, motor functions, and perception. However, higher cognitive functions such as social cognition, personality, and the sense of self may be affected by brain surgery. To date, the precise localization and the network patterns of brain regions involved in such functions are not yet fully understood, making the assessment of risks of related post-surgical deficits difficult. It is in the interest of neurosurgeons to understand with which neural systems related to selfhood and personality they are interfering during surgery. Recent neuroscience research using virtual reality and clinical observations suggest that the insular cortex, medial prefrontal cortex, and temporo-parietal junction are important components of a neural system dedicated to self-consciousness based on multisensory bodily processing, including exteroceptive and interoceptive cues (bodily self-consciousness (BSC)). Here, we argue that combined extra- and intra-operative approaches using targeted cognitive testing, functional imaging and EEG, virtual reality, combined with multisensory stimulations, may contribute to the assessment of the BSC and related cognitive aspects. Although the usefulness of particular biomarkers, such as cardiac and respiratory signals linked to virtual reality, and of heartbeat evoked potentials as a surrogate marker for intactness of multisensory integration for intra-operative monitoring has to be proved, systemic and automatized testing of BSC in neurosurgical patients will improve future surgical outcome.
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http://dx.doi.org/10.1007/s00701-021-04778-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053654PMC
May 2021

Isolated subarachnoid hemorrhage in mild traumatic brain injury: is a repeat CT scan necessary? A single-institution retrospective study.

Acta Neurochir (Wien) 2021 Mar 1. Epub 2021 Mar 1.

Department of Clinical Neurosciences, Division of Neurosurgery, Geneva University Hospitals, Geneva, Switzerland.

Background: Traumatic brain injury (TBI) with isolated subarachnoid hemorrhage (iSAH) is a common finding in the emergency department. In many centers, a repeat CT scan is routinely performed 24 to72 h following the trauma to rule out further radiological progression. The aim of this study is to assess the clinical utility of the repeat CT scan in clinical practice.

Methods: We reviewed the medical charts of all patients who presented to our institution with mild TBI (mTBI) and isolated SAH between January 2015 and October 2017. CT scan at admission and control after 24 to 72 h were examined for each patient in order to detect any possible change. Neurological deterioration, antiplatelet/anticoagulant therapy, coagulopathy, SAH location, associated injuries, and length of stay in hospital were analyzed.

Results: Of the 649 TBI patients, 106 patients met the inclusion criteria. Fifty-four patients were females and 52 were males with a mean age of 68.2 years. Radiological iSAH progression was found in 2 of 106 (1.89) patients, and one of them was under antiplatelet therapy. No neurological deterioration was observed. Ten of 106 (9.4%) patients were under anticoagulation therapy, and 28 of 106 (26.4%) were under antiplatelet therapy.

Conclusion: ISAH in mTBI seems to be a radiological stable entity over 72 h with no neurological deterioration. The clinical utility of a repeat head CT in such patients is questionable, considering its radiation exposure and cost. Regardless of anticoagulation/antiplatelet therapy, neurologic observation and symptomatic treatment solely could be a reasonable alternative.
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http://dx.doi.org/10.1007/s00701-020-04622-0DOI Listing
March 2021

Dr. Strangelove demystified: Disconnection of hand and language dominance explains alien-hand syndrome after corpus callosotomy.

Seizure 2021 Mar 16;86:147-151. Epub 2021 Feb 16.

Department of Neurosurgery, Geneva University Medical Center & Faculty of Medicine, Geneva, Switzerland.

Background: Alien hand syndrome (AHS) is a disabling condition in which one hand behaves in a way that the person finds "alien". This feeling of alienation is related to the occurrence of movements of the respective hand performed without or against conscious intention. Most information on AHS stems from single case observations in patients with frontal, callosal, or parietal brain damage.

Methods: Retrospective analysis of distinctive clinical features of three out of 18 epilepsy patients who developed AHS with antagonistic movements of the left hand after corpus callosotomy (CC) (one anterior, two complete) for the control of epileptic seizures, particularly epileptic drop attacks (EDA).

Results: Remarkably, these three patients, two men and one woman, displayed atypical language dominance with a bilateral, left more than right hemisphere language representation in intracarotidal amobarbital testing before surgery. The overall additional distinctive feature of the target patients was genuine left-handedness, with writing retrained to right-handedness in two patients. After surgery the left hands became alien. The problem was permanent, despite strategies for compensation.

Conclusion: From this observation we suggest that under the conditions of dissociation of language and motor dominance, loss of both intentional control of contralateral action and physiological inhibition of antagonistic movements lead to post-callosotomy alien-hand-like motor phenomena. The dissociation pattern posing this risk seems rare but needs to be considered when evaluating candidates for callosotomy.
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http://dx.doi.org/10.1016/j.seizure.2021.02.013DOI Listing
March 2021

Respond of the different human cranial bones to pin-type head fixation device.

Acta Neurochir (Wien) 2021 04 29;163(4):885-893. Epub 2021 Jan 29.

Department of Neurosurgery, University of Geneva Medical Center & Faculty of Medicine, University of Geneva, Swiss Foundation for Innovation & Training in Surgery (SFITS), Rue Gabrielle-Perret-Gentil 4, Geneva, Switzerland.

Background: At this juncture, there is no consensus in the literature for the use and the safety of pin-type head holders in cranial procedures.

Methods: The present analysis of the bone response to the fixation of the instrument provides data to understand its impact on the entire skull as well as associated complications. An experimental study was conducted on fresh-frozen human specimens to analyze the puncture hole due to the fixation of each single pin of the pin-type head holder. Cone-beam CT images were acquired to measure the diameter of the puncture hole caused by the instrument according to several parameters: the pin angle, the clamping force, and different neurosurgical approaches most clinically used.

Results: The deepest hole, 2.67 ± 0.27 mm, was recorded for a 35° angle and a clamping force of 270 N at the middle fossa approach. The shallowest hole was 0.62 ± 0.22 mm for the 43° angle with a pinning force of 180 N in the pterional approach. The pterional approach had a significantly different effect on the depth of the puncture hole compared with the middle fossa craniotomy for 270 N pinning at 35° angle. The puncture hole measured with the 43° angle and 180 N force in prone position is significantly different from the other approaches with the same force.

Conclusions: These results could lead to recommendations about the use of the head holder depending on the patient's history and cranial thickness to reduce complications associated with the pin-type head holder during clinical applications.
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http://dx.doi.org/10.1007/s00701-021-04728-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966194PMC
April 2021

Sensitivity and Negative Predictive Value of Motor Evoked Potentials of the Facial Nerve.

J Neurol Surg A Cent Eur Neurosurg 2021 Jan 21. Epub 2021 Jan 21.

Hôpitaux Universitaires de Genève, Geneva, Switzerland.

Objective:  The objective of this study was to determine the performance of the standard alarm criterion of motor evoked potentials (MEPs) of the facial nerve in surgeries performed for resections of vestibular schwannomas or of other lesions of the cerebellopontine angle.

Methods:  This retrospective study included 33 patients (16 with vestibular schwannomas and 17 with other lesions) who underwent the resection surgery with transcranial MEPs of the facial nerve. A reproducible 50% decrease in MEP amplitude, resistant to a 10% increase in stimulation intensity, was applied as the alarm criterion during surgery. Facial muscular function was clinically evaluated with the House-Brackmann score (HBS), pre- and postsurgery at 3 months.

Results:  In the patient group with vestibular schwannoma, postoperatively, the highest sensitivity and negative predictive values were found for a 30% decrease in MEP amplitude, that is, a criterion stricter than the 50% decrease in MEP amplitude criterion, prone to trigger more warnings, used intraoperatively. With this new criterion, the sensitivity would be 88.9% and the negative predictive value would be 85.7%. In the patient group with other lesions of the cerebellopontine angle, the highest sensitivity and negative predictive values were found equally for 50, 60, or 70% decrease in MEP amplitude. With these criteria, the sensitivities and the negative predictive values would be 100.0%.

Conclusion:  Different alarm criteria were found for surgeries for vestibular schwannomas and for other lesions of the cerebellopontine angle. The study consolidates the stricter alarm criterion, that is, a criterion prone to trigger early warnings, as found previously by others for vestibular schwannoma surgeries (30% decrease in MEP amplitude).
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http://dx.doi.org/10.1055/s-0040-1719026DOI Listing
January 2021

Craniocervical fractures management in case of craniocervical pneumatization: case report and review of the literature.

Acta Neurochir (Wien) 2021 Jan 3. Epub 2021 Jan 3.

Neurosurgical Unit, Faculty of Medicine, Geneva University Hospitals, University of Geneva, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland.

Introduction: Extensive craniocervical pneumatization (CCP) refers to an abnormal pneumatization extended from the temporal bone into adjacent bone structures, especially the skull base and the craniocervical junction. The etiology remains controversial; however several studies reported a correlation with recurrent Valsalva maneuvers or Eustachian tube dysfunction. Although some cases requiring surgical treatment have been reported, conservative treatment remains the gold standard. The authors aimed to describe a case of CCP, complicated by a spontaneous fracture of a pneumatized left occipital condyle. Furthermore, they reviewed all previously reported cases of fractures in CCP in order to propose a standardized approach to this pathology.

Methods: A total of 148 studies were retrieved. Of those, 23 studies (including 26 patients in addition to our case) were included in the review. These studies consisted of case reports or small case series (up to 3 patients).

Results: In 3 patients (11.1%), bone pneumatization involved C0; all remaining patients had both C0 and C1 pneumatization, while in 7 cases (25.9%), an extension to C2 and/or C3 was reported. Radiological follow-up was performed in 20 patients (74.1%), showing in all of the cases either stability (6 patients, 22.2%), improvement, or complete resolution (6 patients, 22.2% vs 8 patients, 29.7%). Two patients underwent surgical intervention.

Conclusions: This review suggests that fractures secondary to CCP are extremely rare and are associated to a good clinical and radiological outcome with conservative treatment. Ear, nose, and throat (ENT) evaluation is recommended to detect cases who need treatment for a subjacent middle ear disease.
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http://dx.doi.org/10.1007/s00701-020-04683-1DOI Listing
January 2021

Evaluation of the precision of operative augmented reality compared to standard neuronavigation using a 3D-printed skull.

Neurosurg Focus 2021 01;50(1):E17

1Division of Neurosurgery, Department of Clinical Neurosciences, Geneva University Hospitals; and.

Objective: Augmented reality (AR) in cranial surgery allows direct projection of preregistered overlaid images in real time on the microscope surgical field. In this study, the authors aimed to compare the precision of AR-assisted navigation and standard pointer-based neuronavigation (NV) by using a 3D-printed skull in surgical conditions.

Methods: A commercial standardized 3D-printed skull was scanned, fused, and referenced with an MR image and a CT scan of a patient with a 2 × 2-mm right frontal sinus defect. The defect was identified, registered, and integrated into NV. The target was physically marked on the 3D-printed skull replicating the right frontal sinus defect. Twenty-six subjects participated, 25 of whom had no prior NV or AR experience and 1 with little AR experience. The subjects were briefly trained in how to use NV, AR, and AR recalibration tools. Participants were asked to do the following: 1) "target the center of the defect in the 3D-printed skull with a navigation pointer, assisted only by NV orientation," and 2) "use the surgical microscope and AR to focus on the center of the projected object" under conventional surgical conditions. For the AR task, the number of recalibrations was recorded. Confidence regarding NV and AR precision were assessed prior to and after the experiment by using a 9-level Likert scale.

Results: The median distance to target was statistically lower for AR than for NV (1 mm [Q1: 1 mm, Q3: 2 mm] vs 3 mm [Q1: 2 mm, Q3: 4 mm] [p < 0.001]). In the AR task, the median number of recalibrations was 4 (Q1: 4, Q3: 4.75). The number of recalibrations was significantly correlated with the precision (Spearman rho: -0.71, p < 0.05). The trust assessment after performing the experiment scored a median of 8 for AR and 5.5 for NV (p < 0.01).

Conclusions: This study shows for the first time the superiority of AR over NV in terms of precision. AR is easy to use. The number of recalibrations performed using reference structures increases the precision of the navigation. The confidence regarding precision increases with experience.
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http://dx.doi.org/10.3171/2020.10.FOCUS20789DOI Listing
January 2021

Association of Medical Comorbidities With Objective Functional Impairment in Lumbar Degenerative Disc Disease.

Global Spine J 2020 Dec 17:2192568220979120. Epub 2020 Dec 17.

Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.

Study Design: Analysis of a prospective 2-center database.

Objectives: Medical comorbidities co-determine clinical outcome. Objective functional impairment (OFI) provides a supplementary dimension of patient assessment. We set out to study whether comorbidities are associated with the presence and degree of OFI in this patient population.

Methods: Patients with degenerative diseases of the spine preoperatively performed the timed-up-and-go (TUG) test and a battery of questionnaires. Comorbidities were quantified using the Charlson Comorbidity Index (CCI) and the American Society of Anesthesiology (ASA) grading. Crude and adjusted linear regression models were fitted.

Results: Of 375 included patients, 97 (25.9%) presented at least some degree of medical comorbidity according to the CCI, and 312 (83.2%) according to ASA grading. In the univariate analysis, the CCI was inconsistently associated with OFI. Only patients with low-grade CCI comorbidity displayed significantly higher TUG test times (p = 0.004). In the multivariable analysis, this effect persisted for patients with CCI = 1 (p = 0.030). Regarding ASA grade, patients with ASA = 3 exhibited significantly increased TUG test times (p = 0.003) and t-scores (p = 0.015). This effect disappeared after multivariable adjustment (p = 0.786 and p = 0.969). In addition, subjective functional impairment according to ODI, and EQ5D index was moderately associated with comorbidities according to ASA (all p < 0.05).

Conclusion: The degree of medical comorbidities appears only weakly and inconsistently associated with OFI in patients scheduled for degenerative lumbar spine surgery, especially after controlling for potential confounders. TUG testing may be valid even in patients with relatively severe comorbidities who are able to complete the test.
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http://dx.doi.org/10.1177/2192568220979120DOI Listing
December 2020

Incidence and Outcome of Aneurysmal Subarachnoid Hemorrhage: The Swiss Study on Subarachnoid Hemorrhage (Swiss SOS).

Stroke 2021 01 4;52(1):344-347. Epub 2020 Dec 4.

Neuroradiology (L.R., M.D.), Kantonsspital Aarau Switzerland.

Background And Purpose: The purpose of this study was to assess nationwide incidence and outcomes of aneurysmal subarachnoid hemorrhage (aSAH). The Swiss SOS (Swiss Study on Subarachnoid Hemorrhage) was established in 2008 and offers the unique opportunity to provide this data from the point of care on a nationwide level.

Methods: All patients with confirmed aneurysmal subarachnoid hemorrhage admitted between January 1, 2009 and December 31, 2014, within Switzerland were recorded in a prospective registry. Incidence rates were calculated based on time-matched population data. Admission parameters and outcomes at discharge and at 1 year were recorded.

Results: We recorded data of 1787 consecutive patients. The incidence of aneurysmal subarachnoid hemorrhage in Switzerland was 3.7 per 100 000 persons/y. The number of female patients was 1170 (65.5%). With a follow-up rate of 91.3% at 1 year, 1042 patients (58.8%) led an independent life according to the modified Rankin Scale (0-2). About 1 in 10 patients survived in a dependent state (modified Rankin Scale, 3-5; n=185; 10.4%). Case fatality was 20.1% (n=356) at discharge and 22.1% (n=391) after 1 year.

Conclusions: The current incidence of aneurysmal subarachnoid hemorrhage in Switzerland is lower than expected and an indication of a global trend toward decreasing admissions for ruptured intracranial aneurysms. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03245866.
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http://dx.doi.org/10.1161/STROKEAHA.120.029538DOI Listing
January 2021

Surgical treatment and neurological outcome of infiltrating intramedullary astrocytoma WHO II-IV: a multicenter retrospective case series.

J Neurooncol 2021 Jan 22;151(2):181-191. Epub 2020 Oct 22.

Department of Neurosurgery, School of Medicine, Klinikum Rechts Der Isar, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.

Introduction: Primary malignant spinal astrocytomas present rare oncological entities with limited median survival and rapid neurological deterioration. Evidence on surgical therapy, adjuvant treatment, and neurological outcome is sparse. We aim to describe the treatment algorithm and clinical features on patients with infiltrating intramedullary astrocytomas graded WHO II-IV.

Methods: The following is a multicentered retrospective study of patients treated for spinal malignant glioma WHO II-IV in five high-volume neurosurgical departments from 2008 to 2019. Pilocytic astrocytomas were excluded. We assessed data on surgical technique, perioperative neurological status, adjuvant oncological therapy, and clinical outcome.

Results: 40 patients were included (diffuse astrocytoma WHO II n = 11, anaplastic astrocytoma WHO III n = 12, WHO IV n = 17). Only 40% were functionally independent before surgery, most patients presented with moderate disability (47.5%). Most patients underwent a biopsy (n = 18, 45%) or subtotal tumor resection (n = 15, 37.5%), and 49% of the patients deteriorated after surgery. Patients with WHO III and IV tumors were treated with combined radiochemotherapy. Median overall survival (OS) was 46.5 months in WHO II, 25.7 months in WHO III, and 7.4 months in WHO IV astrocytomas. Preoperative clinical status and WHO significantly influenced the OS, and the extent of resection did not.

Conclusion: Infiltrating intramedullary astrocytomas WHO II-IV present rare entities with dismal prognosis. Due to the high incidence of surgery-related neurological impairment, the aim of the surgical approach should be limited to obtaining the histological tissue via a biopsy or, tumor debulking in cases with rapidly progressive severe preoperative deficits.
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http://dx.doi.org/10.1007/s11060-020-03647-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875841PMC
January 2021

Does Spondylolisthesis Affect Severity and Outcome of Degenerative Cervical Myelopathy? A Systematic Review and Meta-analysis.

Global Spine J 2020 Oct 16:2192568220960452. Epub 2020 Oct 16.

27230University of Geneva, Switzerland.

Study Design: This was a systematic review and meta-analysis.

Objectives: Degenerative cervical myelopathy (DCM) with spondylolisthesis remains not well defined, poorly studied, and underreported and plays a minor role in the therapeutic decision-making. Spondylolisthesis, however, is not uncommon and may result in dynamic injury to the spinal cord. We aim to describe the impact of spondylolisthesis in DCM severity and postoperative outcomes.

Methods: Two independent reviewers conducted a Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA 2015)-based review between 1970 and May 2020 for articles reporting outcome of DCM in patients with degenerative cervical spondylolisthesis. Patient clinical and radiological data was recorded at baseline and during postoperative follow-up (FU). A meta-analysis comparing surgical outcome between DCM patients with and without spondylolisthesis assessed by the regular/modified Japanese Orthopaedic Association Assessment Scale (mJOA) recovery ratio was completed.

Results: A total of 3 studies were included (1 ambispective and 2 retrospective cohorts); 607 patients with DCM were identified, 102 (16.8%) of whom also had spondylolisthesis. DCM patients with spondylolisthesis were significantly older ( < .05), presented with worse baseline mJOA and Nurick grades ( < .05 in 2 studies), and were more commonly operated via posterior approaches ( < .05). All groups experienced a (m)JOA and/or Neck Disability Index score improvement during FU. In the pooled meta-analysis, spondylolisthesis patients showed a significantly lower functional recovery ratio at 2 years compared with other DCM patients ( = .05).

Conclusions: Spondylolisthesis is frequent in older DCM patients and may be a predictor of a more advanced degeneration and subsequent worse baseline conditions and postoperative outcome.
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http://dx.doi.org/10.1177/2192568220960452DOI Listing
October 2020

Development of a Complication- and Treatment-Aware Prediction Model for Favorable Functional Outcome in Aneurysmal Subarachnoid Hemorrhage Based on Machine Learning.

Neurosurgery 2021 01;88(2):E150-E157

Department of Neurosurgery, University Hospital Zurich & Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland.

Background: Current prognostic tools in aneurysmal subarachnoid hemorrhage (aSAH) are constrained by being primarily based on patient and disease characteristics on admission.

Objective: To develop and validate a complication- and treatment-aware outcome prediction tool in aSAH.

Methods: This cohort study included data from an ongoing prospective nationwide multicenter registry on all aSAH patients in Switzerland (Swiss SOS [Swiss Study on aSAH]; 2009-2015). We trained supervised machine learning algorithms to predict a binary outcome at discharge (modified Rankin scale [mRS] ≤ 3: favorable; mRS 4-6: unfavorable). Clinical and radiological variables on admission ("Early" Model) as well as additional variables regarding secondary complications and disease management ("Late" Model) were used. Performance of both models was assessed by classification performance metrics on an out-of-sample test dataset.

Results: Favorable functional outcome at discharge was observed in 1156 (62.0%) of 1866 patients. Both models scored a high accuracy of 75% to 76% on the test set. The "Late" outcome model outperformed the "Early" model with an area under the receiver operator characteristics curve (AUC) of 0.85 vs 0.79, corresponding to a specificity of 0.81 vs 0.70 and a sensitivity of 0.71 vs 0.79, respectively.

Conclusion: Both machine learning models show good discrimination and calibration confirmed on application to an internal test dataset of patients with a wide range of disease severity treated in different institutions within a nationwide registry. Our study indicates that the inclusion of variables reflecting the clinical course of the patient may lead to outcome predictions with superior predictive power compared to a model based on admission data only.
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http://dx.doi.org/10.1093/neuros/nyaa401DOI Listing
January 2021

How I do it: retrosigmoid intradural inframeatal petrosectomy.

Acta Neurochir (Wien) 2021 03 28;163(3):649-653. Epub 2020 Sep 28.

Division of Neurosurgery, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland.

Background: Lesions infiltrating the petrous temporal bone are some of the most complex to treat surgically. Many approaches have been developed in order to address these lesions, including endoscopic endonasal, anterior petrosectomy, posterior petrosectomy, and retrosigmoid.

Method: We describe in a stepwise fashion the surgical steps of the retrosigmoid intradural inframeatal petrosectomy.

Conclusion: The retrosigmoid intradural inframeatal petrosectomy may afford satisfactory exposure with limited drilling and minimal disruption of perilesional anatomical structures. It can provide excellent surgical results, especially for soft tumors, while minimizing surgical morbidity.
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http://dx.doi.org/10.1007/s00701-020-04587-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7886824PMC
March 2021

Procedures performed during neurosurgery residency in Europe.

Acta Neurochir (Wien) 2020 10 16;162(10):2303-2311. Epub 2020 Aug 16.

Department of Neurosurgery, Geneva University Hospitals, Geneva, Switzerland.

Background: In a previous article ( https://doi.org/10.1007/s00701-019-03888-3 ), preliminary results of a survey, aiming to shed light on the number of surgical procedures performed and assisted during neurosurgery residency in Europe were reported. We here present the final results and extend the analyses.

Methods: Board-certified neurosurgeons of European Association of Neurosurgical Societies (EANS) member countries were asked to review their residency case logs and participate in a 31-question electronic survey (SurveyMonkey Inc., San Mateo, CA). The responses received between April 25, 2018, and April 25, 2020, were considered. We excluded responses that were incomplete, from non-EANS member countries, or from respondents that have not yet completed their residency.

Results: Of 430 responses, 168 were considered for analysis after checking in- and exclusion criteria. Survey responders had a mean age of 42.7 ± 8.8 years, and 88.8% were male. Responses mainly came from surgeons employed at university/teaching hospitals (85.1%) in Germany (22.0%), France (12.5%), the United Kingdom (UK; 8.3%), Switzerland (7.7%), and Greece (7.1%). Most responders graduated in the years between 2011 and 2019 (57.7%). Thirty-eight responders (22.6%) graduated before and 130 responders (77.4%) after the European WTD 2003/88/EC came into effect. The mean number of surgical procedures performed independently, supervised or assisted throughout residency was 540 (95% CI 424-657), 482 (95% CI 398-568), and 579 (95% CI 441-717), respectively. Detailed numbers for cranial, spinal, adult, and pediatric subgroups are presented in the article. There was an annual decrease of about 33 cases in total caseload between 1976 and 2019 (coeff. - 33, 95% CI - 62 to - 4, p = 0.025). Variables associated with lesser total caseload during residency were training abroad (1210 vs. 1747, p = 0.083) and female sex by trend (947 vs. 1671, p = 0.111), whereas case numbers were comparable across the EANS countries (p = 0.443).

Conclusion: The final results of this survey largely confirm the previously reported numbers. They provide an opportunity for current trainees to compare their own case logs with. Again, we confirm a significant decline in surgical exposure during training between 1976 and 2019. In addition, the current analysis reveals that female sex and training abroad may be variables associated with lesser case numbers during residency.
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http://dx.doi.org/10.1007/s00701-020-04513-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496021PMC
October 2020

Diversity and equality in neurosurgery.

Lancet Neurol 2020 08;19(8):645-646

Department of Neurosurgery, Geneva University Medical Center and Faculty of Medicine, 1205 Geneva, Switzerland.

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http://dx.doi.org/10.1016/S1474-4422(20)30226-XDOI Listing
August 2020

Abnormal directed connectivity of resting state networks in focal epilepsy.

Neuroimage Clin 2020 6;27:102336. Epub 2020 Jul 6.

EEG and Epilepsy Unit, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Geneva, Switzerland.

Objective: Epilepsy diagnosis can be difficult in the absence of interictal epileptic discharges (IED) on scalp EEG. We used high-density EEG to measure connectivity in large-scale functional networks of patients with focal epilepsy (Temporal and Extratemporal Lobe Epilepsy, TLE and ETLE) and tested for network alterations during resting wakefulness without IEDs, compared to healthy controls. We measured global efficiency as a marker of integration within networks.

Methods: We analysed 49 adult patients with focal epilepsy and 16 healthy subjects who underwent high-density-EEG and structural MRI. We estimated cortical activity using electric source analysis in 82 atlas-based cortical regions based on the individual MRI. We applied directed connectivity analysis (Partial Directed Coherence) on these sources and performed graph analysis: we computed the Global Efficiency on the whole brain and on each resting state network. We tested these features in different group of patients.

Results: Compared to controls, efficiency was increased in both TLE and ETLE (p < 0.05). The somato-motor-network, the ventral-attention-network and the default-mode-network had a significantly increased efficiency (p < 0.05) in both TLE and ETLE as well as TLE with hippocampal sclerosis.

Significance: During interictal scalp EEG epochs without IED, patients with focal epilepsy show brain functional connectivity alterations in the whole brain and in specific resting-state-networks. This higher integration reflects a chronic effect of pathological activity within these structures and complement previous work on altered information outflow. These findings could increase the diagnostic sensitivity of scalp EEG to identify epileptic activity in the absence of IED.
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http://dx.doi.org/10.1016/j.nicl.2020.102336DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363703PMC
July 2020

Navigation assisted tubular resection of lumbar osteoid osteoma: how I do it.

Acta Neurochir (Wien) 2020 11 10;162(11):2933-2937. Epub 2020 Jun 10.

Neurosurgical Unit, Faculty of Medicine, Geneva University Hospitals, University of Geneva, Rue Gabrielle-Perret-Gentil 4, 1205, Geneva, Switzerland.

Background: Osteoid osteoma is a benign primary bony tumor involving the spinal posterior arches. Surgical treatment is reserved to patients with severe pain or not responding to nonsteroidal anti-inflammatory medications. We report a minimally invasive transmuscular resection of an L5 isthmic osteoid osteoma, assisted by intraoperative 3D-fluoroscopy-based navigation.

Methods: Navigation tracking reference is placed on the spinous process. A simil-scan with 3D-fluoroscopy is obtained to allow autoregistration for spinal navigation. Tubular transmuscular approach, directed to the ipsilateral isthmus and pedicle, is performed. Under navigation guidance, the lesion is identified and removed.

Conclusion: This technique is a safe and effective minimally invasive alternative to conventional surgical treatment of lumbar osteoid osteoma.
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http://dx.doi.org/10.1007/s00701-020-04443-1DOI Listing
November 2020

Role of Robotics in Improving Surgical Outcome in Spinal Pathologies.

World Neurosurg 2020 08 21;140:664-673. Epub 2020 May 21.

Neurosurgical Unit, Geneva University Hospitals, University of Geneva, Faculty of Medicine, Geneva, Switzerland.

Background: The desire to improve accuracy and safety and to favor minimally invasive techniques has given rise to spinal robotic surgery, which has seen a steady increase in utilization in the past 2 decades. However, spinal surgery encompasses a large spectrum of operative techniques, and robotic surgery currently remains confined to assistance with the trajectory of pedicle screw insertion, which has been shown to be accurate and safe based on class II and III evidence. The role of robotics in improving surgical outcomes in spinal pathologies is less clear, however.

Methods: This comprehensive review of the literature addresses the role of robotics in surgical outcomes in spinal pathologies with a focus on the various meta-analysis and prospective randomized trials published within the past 10 years in the field.

Results: It appears that robotic spinal surgery might be useful for increasing accuracy and safety in spinal instrumentation and allows for a reduction in surgical time and radiation exposure for the patient, medical staff, and operator.

Conclusion: Robotic assisted surgery may thus open the door to minimally invasive surgery with greater security and confidence. In addition, the use of robotics facilitates tireless repeated movements with higher precision compared with humans. Nevertheless, it is clear that further studies are now necessary to demonstrate the role of this modern tool in cost-effectiveness and in improving clinical outcomes, such as reoperation rates for screw malpositioning.
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http://dx.doi.org/10.1016/j.wneu.2020.05.132DOI Listing
August 2020