The prevalence of imposter syndrome among neurosurgeons in Europe: An EANS YNC survey.

Introduction: Imposter syndrome (IS), characterized by persistent doubts about one's abilities and fear of exposure as a fraud, is a prevalent psychological condition, particularly impacting physicians. In neurosurgery, known for its competitiveness and demands, the prevalence of IS remains high. Research question: Recognizing the limited literature on IS within the neurosurgical community, this European survey aimed to determine its prevalence among young neurosurgeons and identify associated factors. Material and methods: The survey, conducted by the Young Neurosurgeon Committee of the European Association of Neurosurgical Societies, gathered responses from 232 participants. The survey included demographics, the Clance Imposter Phenomenon Survey (CIPS), and an analysis of potential compensatory mechanisms. Results: Nearly 94% of respondents exhibited signs of IS, with the majority experiencing moderate (36.21%) or frequent (40.52%) symptoms. Analyses revealed associations between IS and factors such as level of experience, sex, and board-certification. Discussion and conclusion: The findings suggest a significant prevalence of IS among young neurosurgeons, with notable associations with sex and level of experience. Compensatory mechanisms, such as working hours, article reading, and participation in events, did not show significant correlations with IS. Notably, male sex emerged as an independent protective factor against frequent/intense IS, while reading more than five articles per week was identified as a risk factor. The identification of protective and risk factors, particularly the influence of gender and reading habits, contributes valuable insights for developing targeted interventions to mitigate IS and improve the well-being of neurosurgeons.

Clinical Depression and Anxiety Are Relieved by Microvascular Decompression in Patients with Trigeminal Neuralgia-A Prospective Patient-Reported Outcome Study.

Objective: Patients with idiopathic trigeminal neuralgia (TN) live in constant fear of triggering shock-like pain episodes, which may cause symptoms of depression and a reduction in quality of life. Microvascular decompressive surgery has been demonstrated to achieve satisfactory and stable results. With this study, we wanted to investigate prevalence and risk factors for depression and perceived stress in correlation with symptom relief after surgical treatment. Methods: In this prospective study, patients undergoing microvascular decompression (MVD) for TN were included. The Barrow Neurological Institute Pain Score (BNI), Beck Depression Inventory (BDI), Chronic Pain Acceptance Questionnaire (CPAQ), Perceived Stress Questionnaire (PSQ) and McGill questionnaire were used to evaluate depression, stress and anxiety disorders before and 3 months after MVD. Results: A total of 35 patients (16 male (46%)) with a mean age of 55.4 (SD 15) years were included in this study. The BDI revealed that 24 (68.8%) patients harbored mild-to-extreme depression preoperatively (2.4 ± 1.4), which improved to 1.2 (±0.6, p < 0.0001). Pain acceptance also changed from 64 (±11.3) to 67.7 (±9.3, p = 0.006). Perceived stress decreased from 46.9 (±21.9) to 19.6 (±18.6) (p < 0.0001) postoperatively, and pain decreased from 31.0 (±11.7) to 9.4 (±12.9, p < 0.0001). Microvascular decompression reduced the mean BNI pain score significantly from 4.6 to 1.8 postoperatively (p < 0.00001). Conclusions: Depression and perceived stress are prevalent in patients with idiopathic TN. Adequate treatment not only provides a high rate of satisfaction through pain relief, but also leads to immediate and significant improvements in depression and stress. Thus, in patients with TN who do not reach an adequate and timely pain reduction through medical management and develop signs of depression, early treatment with microvascular decompression should be considered.

Cadaveric study of ergonomics and performance using a robotic exoscope with a head-mounted display in spine surgery.

The conventional microscope has the disadvantage of a potentially unergonomic posture for the surgeon, which can affect performance. Monitor-based exoscopes could provide a more ergonomic posture, as already shown in pre-clinical studies. The aim of this study was to test the usability and comfort of a novel head-mounted display (HMD)-based exoscope on spinal surgical approaches in a simulated OR setting. A total of 21 neurosurgeons naïve to the device were participated in this prospective trial. After a standardized training session with the device, participants were asked to perform a single-level thoracolumbar decompression surgery on human cadavers using the exoscope. Subsequently, all participants completed a comfort and safety questionnaire. For the objective evaluation of the performance, all interventions were videotaped and analyzed. Twelve men and nine women with a mean age of 34 (range: 24-57) were participating in the study. Average time for decompression was 15 min (IqR 9.6; 24.2); three participants (14%) terminated the procedure prematurely. In these dropouts, a significantly higher incidence of back/neck pain (p = 0.002 for back, p = 0.046 for neck pain) as well as an increased frequency of HMD readjustments (p = 0.045) and decreased depth perception (p = 0.03) were documented. Overall, the surgeons' satisfaction with the exoscope was 84% (IqR 75; 100). Using a standardized, pre-interventional training, it is possible for exoscope-naïve surgeons to perform sufficient spinal decompression using the HMD-based exoscope with a high satisfaction. However, inaccurate HMD setup prior to the start of the procedure may lead to discomfort and unsatisfactory results.

Radiomic features define risk and are linked to DNA methylation attributes in primary CNS lymphoma.

Background: The prognostic roles of clinical and laboratory markers have been exploited to model risk in patients with primary CNS lymphoma, but these approaches do not fully explain the observed variation in outcome. To date, neuroimaging or molecular information is not used. The aim of this study was to determine the utility of radiomic features to capture clinically relevant phenotypes, and to link those to molecular profiles for enhanced risk stratification. Methods: In this retrospective study, we investigated 133 patients across 9 sites in Austria (2005-2018) and an external validation site in South Korea (44 patients, 2013-2016). We used T1-weighted contrast-enhanced MRI and an L1-norm regularized Cox proportional hazard model to derive a radiomic risk score. We integrated radiomic features with DNA methylation profiles using machine learning-based prediction, and validated the most relevant biological associations in tissues and cell lines. Results: The radiomic risk score, consisting of 20 mostly textural features, was a strong and independent predictor of survival (multivariate hazard ratio = 6.56 [3.64-11.81]) that remained valid in the external validation cohort. Radiomic features captured gene regulatory differences such as in BCL6 binding activity, which was put forth as testable treatment target for a subset of patients. Conclusions: The radiomic risk score was a robust and complementary predictor of survival and reflected characteristics in underlying DNA methylation patterns. Leveraging imaging phenotypes to assess risk and inform epigenetic treatment targets provides a concept on which to advance prognostic modeling and precision therapy for this aggressive cancer.

The use of advanced technology for preoperative planning in cranial surgery - A survey by the EANS Young Neurosurgeons Committee.

Introduction: Technological advancements provided several preoperative tools allowing for precise preoperative planning in cranial neurosurgery, aiming to increase the efficacy and safety of surgery. However, little data are available regarding if and how young neurosurgeons are trained in using such technologies, how often they use them in clinical practice, and how valuable they consider these technologies. Research question: How frequently these technologies are used during training and clinical practice as well as to how their perceived value can be qualitatively assessed. Materials and methods: The Young Neurosurgeons' Committee (YNC) of the European Association of Neurosurgical Societies (EANS) distributed a 14-items survey among young neurosurgeons between June 1st and August 31st, 2022. Results: A total of 441 responses were collected. Most responders (42.34%) received "formal" training during their residency. Planning techniques were used mainly in neuro-oncology (90.86%), and 3D visualization of patients' DICOM dataset using open-source software was the most frequently used (>20 times/month, 20.34% of responders). Software for 3D visualization of patients' DICOM dataset was the most valuable technology, especially for planning surgical approach (42.03%). Conversely, simulation based on augmented/mixed/virtual reality was considered the less valuable tool, being rated below sufficiency by 39.7% of responders. Discussion and conclusion: Training for using preoperative planning technologies in cranial neurosurgery is provided by neurosurgical residency programs. Software for 3D visualization of DICOM datasets is the most valuable and used tool, especially in neuro-oncology. Interestingly, simulation tools based on augmented/virtual/mixed reality are considered less valuable and, therefore, less used than other technologies.

Surgeon's comfort: The ergonomics of a robotic exoscope using a head-mounted display.

Introduction: Conventional microscopes have certain limitations in terms of posture and ergonomics. Monitor-based exoscopes could solve this problem and thereby lead to less work-related sick leave for surgeons. Research question: The aim of this study was to assess the ergonomics, usability, and neurosurgeon's comfort of a novel three-dimensional head-mounted display-based exoscope in a standardized setting. Material & Methods: 34 neurosurgeons participated in a workshop on the exoscope, which features a head-mounted display and a head gesture-triggered control panel. After completion of a custom-made 10-step microsurgical exercise, image quality and comfort were assessed using a questionnaire. The participants' posture during the exercise was analyzed using a video motion analysis software. Results: 34 participants (median neurosurgical experience: 6 years) were included. The median time to complete the exercise was 12 â€‹min [IqR 9.4, 15.0]. Younger participants (p â€‹= â€‹0.005) and those with video game experience (p â€‹= â€‹0.03) had a significantly steeper learning curve. The median overall satisfaction was at 80% in general and 82% for image quality. The median upper body as well as the median head coronal displacement from the neutral axis were 0°. Participants with less microsurgical experience showed less head/body displacement during the exercise (p â€‹= â€‹0.01). Discussion and conclusion: Using the microsurgical training tool, we were able to depict a steep learning curve with a sufficient learnability of the most relevant commands. The exoscope excelled in usability, image quality as well as in ergonomic and favorable posture and could thus become an alternative to conventional microscopes due to the potentially elevated surgeons' comfort.

Women in neurosurgery: review of the literature combined with a gender-based analysis of the development over the past 20 years in Austria.

BACKGROUND: The number of female neurosurgeons has grown over the last decades, however, a gender gap still exists in most western countries. The reasons for this gender gap remain mostly unclear. The aim of the present study was to analyze the development of the numbers of female neurosurgeons in Austria over the last 20 years in comparison to other surgical disciplines. Additionally, a literature review was performed summarizing articles reporting on women in neurosurgery. METHODS: Data including male and female residents as well as board certified surgeons over the last 20 years retrieved from the Austrian Medical Association were collected. An additional PubMed query was performed focusing on literature reporting on working conditions, work-life-balance as well as data of female leading positions. RESULTS: In 2021, 5237 surgeons were registered at the Austrian Medical Association including 258 (5%) neurosurgeons. In total, 1081 of 5237 (21%) surgeons and 61 of 253 (24%) of all Austrian neurosurgeons were female. In comparison to the percentage of women in all surgical disciplines, the number of female neurosurgeons is represented slightly above the average of 21%. According to data representing the trend of the last 20 years, the percentage of female neurosurgeons in Austria has doubled over the last 20 years. Comparably, this trend can be observed in all surgical disciplines. CONCLUSIONS: The percentage of female neurosurgeons in Austria are constantly increasing over the last 20 years, however a gender gap still exists. Consequently, studies are warranted to analyse the causes to improve the reported gender gap in Neurosurgery.

Craniotomy size for traumatic acute subdural hematomas in elderly patients-same procedure for every age?

Surgical treatment of acute subdural hematoma (aSDH) is still matter of debate, especially in the elderly. A retrospective study to compare two different surgical approaches, namely standard (SC, craniotomy size > 8 cm) and limited craniotomy (LC, craniotomy size < 8 cm), was conducted in elderly patients with traumatic aSDH to identify the role of craniotomy size in terms of clinical and radiological outcome. Sixty-four patients aged 75 or older with aSDH as sole lesion were retrospectively analyzed. Data were collected pre- and postoperatively including clinical and radiological criteria. The primary outcome parameter was 30-day mortality. Secondary outcome parameters were radiological. The mean age was 79.2 (± 3.1) years with no difference between groups and almost equal distribution of craniotomy size. Mortality rate was significantly higher in the SC group in comparison to the LC group (68.4% vs. 31.6%; p = 0.045). The preoperative HD (p = 0.08) and the MLS (p = 0.09) were significantly higher in the SC group, whereas postoperative radiological evaluation showed no significant difference in HD or MLS. A limited craniotomy is sufficient for adequate evacuation of an aSDH in the elderly achieving the same radiological and clinical outcome.

Adrenaline improves regional cerebral blood flow, cerebral oxygenation and cerebral metabolism during CPR in a porcine cardiac arrest model using low-flow extracorporeal support.

BACKGROUND: The effects of adrenaline on cerebral blood vessels during cardiopulmonary resuscitation (CPR) are not well understood. We developed an extracorporeal CPR model that maintains constant low systemic blood flow while allowing adrenaline-associated effects on cerebral vasculature to be assessed at different mean arterial pressure (MAP) levels independently of the effects on systemic blood flow. METHODS: After eight minutes of cardiac arrest, low-flow extracorporeal life support (ECLS) (30 ml/kg/min) was started in fourteen pigs. After ten minutes, continuous adrenaline administration was started to achieve MAP values of 40 (n = 7) or 60 mmHg (n = 7). Measurements included intracranial pressure (ICP), cerebral perfusion pressure (CePP), laser-Doppler-derived regional cerebral blood flow (CBF), cerebral regional oxygen saturation (rSO2), brain tissue oxygen tension (PbtO2) and extracellular cerebral metabolites assessed by cerebral microdialysis. RESULTS: During ECLS without adrenaline, regional CBF increased by only 5% (25th to 75th percentile: -3 to 14; p = 0.2642) and PbtO2 by 6% (0-15; p = 0.0073) despite a significant increase in MAP to 28 mmHg (25-30; p < 0.0001) and CePP to 10 mmHg (8-13; p < 0.0001). Accordingly, cerebral microdialysis parameters showed a profound hypoxic-ischemic pattern. Adrenaline administration significantly improved regional CBF to 29 ± 14% (p = 0.0098) and 61 ± 25% (p < 0.001) and PbtO2 to 15 ± 11% and 130 ± 82% (both p < 0.001) of baseline in the MAP 40 mmHg and MAP 60 mmHg groups, respectively. Importantly, MAP of 60 mmHg was associated with metabolic improvement. CONCLUSION: This study shows that adrenaline administration during constant low systemic blood flow increases CePP, regional CBF, cerebral oxygenation and cerebral metabolism.

Repeated 31P-Magnetic Resonance Spectroscopy in Severe Traumatic Brain Injury: Insights into Cerebral Energy Status and Altered Metabolism.

Phosphorous magnetic resonance spectroscopy (31P-MRS) is suited to noninvasively investigate energy metabolism and to detect molecules containing phosphorus in the human brain. The aim of this longitudinal study was to perform 31P-MRS at two different time points (within 72 h and between day 10-14) after severe traumatic brain injury (sTBI) to reveal alterations in cerebral energy metabolism. Twenty-six ventilated patients with sTBI, aged between 20 and 75 years, with a median initial Glasgow Coma Scale score of 5 were analyzed prospectively. The 31P-MRS data of the structurally more affected side were compared with data from contralateral normal appearing areas and with data of age- and gender-matched healthy controls. There were no significant intraindividual differences between the lesioned and the less affected side at either of the time points. In the acute phase, phosphocreatine/adenosine triphosphate (PCr/ATP) and phosphocreatine/inorganic phosphate (PCr/Pi) were significantly elevated whereas phosphomonoesters/phosphodiesters (PME/PDE) and Pi/ATP were significantly decreased in contrast to healthy controls. In the subacute phase, these differences gradually dissipated, remaining lower Pi/ATP ratio, and only partly altered levels of PCr/Pi and PME/PDE. Our data affirm that cerebral metabolism is globally altered after sTBI, demonstrating the diffuse impairment of brain bioenergetics at multiple levels, with resultant developments in terms of time.

Passive leg raising in brain injury patients within the neurointensive care unit. A prospective trial.

INTRODUCTION: In critically ill brain-injured patients maintaining balanced fluid management is a crucial part of critical care. Many factors influence the relationship between fluid management, cerebral blood flow and cerebral oxygenation. Passive leg raising (PLR)-induced changes predict fluid responsiveness in the majority of non-neurological ICU patients. In patients with intracranial lesions, PLR testing has been hypothesized to increase intracranial pressure (ICP), although data are lacking. We wanted to investigate the feasibility of PLR with expected intracranial pressure increase, according to the higher cerebral blood volume. This should be self-limiting in patients with intact cerebral autoregulation. MATERIAL AND METHODS: We prospectively included patients with traumatic brain injury (TBI) or aneurysmal subarachnoid hemorrhage (aSAH) in this pilot trial. PLR was performed within 48 hours after the initial diagnosis and on days 5-8. All patients had ICP monitoring. Absence of intracranial hypertension (defined as ICP < 25 mm Hg) was considered a positive test result. RESULTS: Ten patients were recruited for this study. The cohort consisted of 6 male patients with TBI and 4 female patients with aSAH. Mean patient age was 55.6 years (range 35-76). Overall, 18 tests could be performed, of which only one had to be terminated due to temporarily elevated ICP. 9 out of 10 patients had no intracranial hypertension during the acute (mean ICP increase 8.45 mm Hg, range 4-16) or during the subacute phase (mean ICP increase 9.12 mm Hg, range 3-18). CONCLUSIONS: PLR is feasible in patients with intracranial pathology to assess fluid responsiveness and provide optimized patient volume management without increasing the risk of persistent intracranial hypertension.

Cerebral Energy Status and Altered Metabolism in Early Severe TBI: First Results of a Prospective 31P-MRS Feasibility Study.

OBJECTIVE: Severe traumatic brain injury (sTBI) represents a serious public health issue with high morbidity and mortality. Neuroimaging plays a crucial role in the evaluation of sTBI patients. Phosphorous magnetic resonance spectroscopy (31P-MRS) is an imaging technique for evaluation of energy metabolites. The aim of this study is to evaluate the feasibility and the diagnostic potential of ultra-early 31P-MRS to detect changes in cerebral energy metabolism in sTBI. METHODS: Adult patients with sTBI presenting with GCS ≤ 8 being eligible for MRI were prospectively included in the study and MRI was performed within 72 h after trauma. Imaging was performed using a 3 Tesla MRI. 31P-MRS data from the structurally affected side were compared to data from normal appearing contralateral areas symmetrically to the location of the traumatic lesions, and to data of matched healthy controls. RESULTS: Ten sTBI patients (3 female, 7 male), aged between 20 and 75 years, with a mean initial GCS of 6 were analyzed. MRI was performed 61 h (mean, range 37-71 h) after trauma. Statistical analysis revealed no significant differences between the lesioned side and contralaterally. An increased PCr/ATP ratio and a decreased PME/PDE ratio were present in structurally normal appearing, but traumatized tissue when compared to the healthy population, thus indicating significant differences in ATP resynthesis and membrane turnover (F (2,33), P = 0.005 and, P = 0.027, respectively). CONCLUSION: 31P-MRS could provide a better understanding of pertinent global changes in cerebral energy metabolism in sTBI patients under general anesthesia.

Safety of Early MRI Examinations in Severe TBI: A Test Battery for Proper Patient Selection.

Introduction: Early magnetic resonance imaging (MRI) provides important information for management and prognosis in patients with severe traumatic brain injury (sTBI). Yet, optimal timing of MRI remains unknown. The aim of our study was to evaluate the safety of early MRI and to identify a method for appropriate patient selection to minimize adverse events related to the intrahospital transport (IHT) and the MRI examination. Methods: Twenty-six patients with sTBI [mean Glasgow Coma Scale (GCS) 6, range 3-8] admitted to our neurosurgical ICU from 03/2015 to 12/2017 and receiving at least one MRI within the first 14 days after initial traumatic event were prospectively included in the study. The following requirements were fulfilled for at least 4 h prior to anticipated MRI: MAP > 70 mmHg, aPCO2 30-40 mmHg, stable ICP < 25 mmHg. All relevant cardiopulmonary and cerebral parameters and medication were recorded. The following MRI sequences were performed: DWI, FLAIR, 3D T2-space, 3D T1 MPRAGE, 3D SWI, 3D TOF, pASL, and 1H/31P-MRS. Results: Four females and 22 males (aged 23-78 years, mean 46.4 years) with a median GCS on admission of 5 (range 3-8) were analyzed. In total, 40 IHTs were performed within the first 14 days (mean 6 days, range 1-14 days). Mean pre-MRI ICP was 14.1 mmHg (range 3-32 mmHg). The mean post-MRI ICP was 14.3 mmHg (range 3-29 mmHg), decreasing to a mean ICP of 13.2 mmHg after 1 h (range 3-29 mmHg). There were no significant differences in ICP measurements before and after MRI (p = 0.30). MAP remained stable with no significant changes during the entire IHT and MRI. No other adverse events were observed as well. Conclusion: Early MRI in acute severe TBI is feasible and safe. Yet, careful patient selection with prior adequate testing of cardiopulmonary and cerebral parameters is crucial to minimize transport- or examination-related morbidity.

The Volume of Ischemic Brain Predicts Poor Outcome in Patients with Surgically Treated Malignant Stroke.

BACKGROUND: Malignant middle cerebral artery stroke is a life-threatening condition. The outcomes of surgical treatments have presented strong evidence in favor of decompressive hemicraniectomy (DHC). A significant subpopulation of patients still experience very poor outcomes. In particular, indication for DHC is based on few objective parameters to facilitate decision making. We hypothesized that larger ischemic brain volume would have a large impact on the outcome. METHODS: A cohort study of 34 patients undergoing DHC was performed using a volumetric analysis of infarction volume (measured preoperatively and again on postoperative day [POD] 1 and POD 3). Outcomes were assessed using the modified Rankin Scale (mRS), and a favorable outcome was defined as modified Rankin Scale score ≤3. RESULTS: Median age of patients was 53.5 years (range, 25-72 years), the median time from onset of first symptoms to surgical intervention was 38 hours (range, 10-150 hours), and male-to-female ratio was 2:1. The median ischemic volume was 250 cm3 preoperatively, 315 cm3 on POD1, and 349 cm3 on POD3. Modified Rankin Scale score ≤3 after 6 months was attained in 7 (20%) patients. Within the first 24 hours after DHC, ischemic volume increased significantly (P = 0.0003) and was associated with a worse outcome (P < 0.0001) after exceeding a cutoff volume of 300 cm3. CONCLUSIONS: Volumetric analysis of infarction can predict the outcome of patients. DHC should be reserved for patients with prognosticated good outcome, which was observed only in patients with a volume <301 cm3.

Routine Postoperative Computed Tomography Is Not Helpful After Elective Craniotomy.

BACKGROUND: Next-day postoperative computed tomography (CT) has been routinely used to obtain radiographic "clearance" for transferring patients after elective craniotomy out of the intensive care unit. The value of this traditional policy, however, has repeatedly been questioned. However, the limited patient numbers might have underestimated the very rare, but catastrophic, events. Therefore, we analyzed the value of routine postoperative CT in a larger cohort of elective tumor, epilepsy, and vascular cases. METHODS: All the patients who had undergone elective craniotomy were included in our study. The routine postoperative CT scans were analyzed by a neuroradiologist who was unaware of the clinical data. The medical records were retrospectively reviewed for events of arterial hypertension and clinical deterioration. RESULTS: The data from 660 patients with tumors (n = 393; 59.5%), aneurysms (n = 107; 16.2%), and skull base lesions were evaluated. In nearly one half of the patients (n = 264; 45.8%), CT depicted the presence of blood that was not associated with symptoms. Of the 660 patients, 21 (3.6%) showed a mass effect radiographically, 11 of whom underwent revision surgery. Arterial hypertension was documented in only 8 patients (1.3%) and was related to the revision surgery (P = 0.018). The overall revision rate was 2.7% (n = 18). All patients who had undergone revision for postoperative hematoma had presented with a new neurological deficit immediately before CT. CONCLUSION: Routine postoperative CT did not reveal 1 patient with a serious hematoma that would not have been identified by clinical examination. Patients could be transferred safely from the intensive care unit, if the weaning process and clinical observation findings were uneventful, without deterioration of neurological symptoms or consciousness.

Accuracy Validation of Neuronavigation Comparing Headholder-Based System with Head-Mounted Array-A Cadaveric Study.

BACKGROUND: Neuronavigation is widely used for intracranial neurosurgical procedures and is commonly based on the standard reference array being fixed to the headholder. Some cases require the reference array to be attached directly to the head. The aim of this cadaveric study was to compare operational accuracy of a head-mounted reference array with the standard headholder-based system. METHODS: Navigation accuracy was evaluated with 10 cadaveric specimens. Each specimen was prepared with 8 titanium microscrews that served as reference points on the external skull, and computed tomography was performed. Registration of all specimens was done using surface matching with infrared laser on three-dimensional reconstructed high-resolution computed tomography. In all 10 specimens, the head-mounted reference array and headholder-based system were compared by 10 repetitive measurements. The deviation was evaluated for each screw and compared using nonparametric Mann-Whitney U test between groups and screws. A Bland-Altman plot was generated for comparison. RESULTS: A total of 1600 measurements were conducted. Mean deviation was 1.97 mm (95% confidence interval, 1.90-2.03 mm) with the head-mounted reference array and 2.10 mm (95% confidence interval, 2.04-2.18 mm) with the headholder based system. There was no significant difference between methods in 9 of 10 specimens. In 1 specimen, the head-mounted array was superior. The deviation in either method showed a significant correlation, indicating high pertinence for registration (P < 0.001). CONCLUSIONS: Navigation with the head-mounted reference array demonstrated comparable accuracy to the headholder-based system and can be used without reduced accuracy. Careful registration is mandatory.

Refractory intracranial hypertension in traumatic brain injury: Proposal for a novel score to assess the safety of lumbar cerebrospinal fluid drainage.

BACKGROUND: Cerebrospinal fluid (CSF) drainage via ventricular puncture is an established therapy of elevated intracranial pressure (ICP). In contrast, lumbar CSF removal is believed to be contraindicated with intracranial hypertension. METHODS: We investigated the safety and efficacy of lumbar CSF drainage to decrease refractory elevated ICP in a small cohort of patients with traumatic brain injury (TBI). A score (0-8 points) was used to assess computed tomography (CT) images for signs of herniation and for patency of the basal cisterns. All patients received lumbar CSF drainage either as a continuous drainage or as a single lumbar puncture (LP). Type and method of CSF drainage, mean ICP 24 h prior and after CSF removal, and adverse events were documented. Outcome was assessed after 3 months (with dichotomized Glasgow outcome scale). RESULTS: Eight patients were evaluated retrospectively. n = 5 suffered a moderate, n = 2 a severe TBI (one Glasgow coma score not documented). The CT score was ≥5 in all patients prior to LP and decreased after puncture without clinical consequences in two patients. The amount of CSF removal did not correlate with score changes (P = 0.45). CSF drainage led to a significant reduction of mean ICP (from 22.3 to 13.9 mmHg, P = 0.002). Continuous drainage was more effective than a single LP. Three of eight patients reached a favorable outcome. CONCLUSIONS: Lumbar CSF removal for the treatment of intracranial hypertension is effective and safe, provided the basal cisterns are discernible, equivalent to ≥5 points in the proposed new score. The score needs further validation.

Effect of cage design, supplemental posterior instrumentation and approach on primary stability of a lumbar interbody fusion - A biomechanical in vitro study.

BACKGROUND: There are various techniques and approaches for lumbar interbody fusion differing in access, cage type and type of supplemental posterior instrumentation. While a transforaminal access usually includes a hemifacetectomy, the facet joint can be preserved with a more lateral extraforaminal access. The supplemental posterior instrumentation required for both fusion techniques is still debated. The purpose of the present study was to compare primary stability of the two accesses for two different cage types with none, unilateral and bilateral supplemental posterior instrumentation. METHODS: Six monosegmental lumbar functional spinal units (FSUs) were included in each of the two groups, and subjected to a flexibility test. As cages, a newly designed cage was compared to a standard cage in the following states: (a) native, (b) stand-alone cage, (c) bilateral internal fixator, (d) unilateral internal fixator, (e) unilateral facetectomy+bilateral internal fixator, (f) unilateral facetectomy+unilateral internal fixator and (g) unilateral facetectomy with stand-alone cage. For comparison the range of motion was normalized to the native state and the effects of the facetectomy, cage type, and supplemental instrumentation was compared. FINDINGS: Within the subject comparison showed a significantly higher flexibility for the unilateral facetectomy in all motion directions (p<0.001). In between subject comparison showed a significant effect of cage type on flexibility in flexion/extension (p=0.002) and lateral bending (p=0.028) but not in axial rotation (p=0.322). The type of supplemental posterior fixation had a significant effect on the flexibility in all motion directions (stand-alone>unilateral fixator>bilateral fixator). INTERPRETATION: Cage design and approach type are affecting the primary stability of lumbar interbody fusion procedures while the type of posterior instrumentation is the most influencing factor.

Timing of PMMA cement application for pedicle screw augmentation affects screw anchorage.

INTRODUCTION: Cement augmentation is an established method to increase the pedicle screw (PS) anchorage in osteoporotic vertebral bodies. The ideal timing for augmentation when a reposition maneuver is necessary is controversial. While augmentation of the PS before reposition maneuver may increase the force applied it on the vertebrae, it bears the risk to impair PS anchorage, whereas augmenting the PS after the maneuver may restore this anchorage and prevent early screw loosening. The purpose of the present study was to evaluate the effect of cement application timing on PS anchorage in the osteoporotic vertebral body. METHODS: Ten lumbar vertebrae (L1-L5) were used for testing. The left and right pedicles of each vertebra were instrumented with the same PS size and used for pairwise comparison of the two timing points for augmentation. For the reposition maneuver, the left PS was loaded axially under displacement control (2 × ±2 mm, 3 × ±6 mm, 3 × ±10 mm) to simulate a reposition maneuver. Subsequently, both PS were augmented with 2 ml PMMA cement. The same force as measured during the left PS maneuver was applied to the previously augmented right hand side PS [2 × F (±2 mm), 3 × F (±6 mm), 3 × F (±10 mm)]. Both PS were cyclically loaded with initial forces of +50 and -50 N, while the lower force was increased by 5 N every 100 cycles until total failure of the PS. The PS motion was measured with a 3D motion analysis system. After cyclic loading stress, X-rays were taken to identify the PS loosening mechanism. RESULTS: In comparison with PS augmented prior to the reposition maneuver, PS augmented after the reposition maneuver showed a significant higher number of load cycles until failure (5930 ± 1899 vs 3830 ± 1706, p = 0.015). The predominant loosening mechanism for PS augmented after the reposition maneuver was PS toggling with the attached cement cloud within the trabecular bone. While PS augmented prior to the reposition, maneuver showed a motion of the screw within the cement cloud. CONCLUSION: The time of cement application has an effect on PS anchorage in the osteoporotic vertebral body if a reposition maneuver of the instrumented vertebrae is carried out. PS augmented after the reposition maneuver showed a significant higher number of load cycles until screw loosening.