Background: There is growing evidence for the use of augmented reality (AR) in pedicle screw placement in spinal surgery to increase surgical accuracy, improve clinical outcomes and reduce the radiation exposure required for intraoperative navigation. Auto-segmentation is the cornerstone of AR applications because it correlates patient-specific anatomy to structures segmented from preoperative computed tomography (pCT) images. These AR techniques allow for a reduction in the radiation dose required to acquire CT images while maintaining accurate segmentation. Methods: In this study, we methodically increase the noise that is introduced into CT images to determine the image quality threshold that is required for auto-segmentation on pCT. We then enhance the images with denoising algorithms to evaluate the effect on the segmentation. Results: The pCT radiation dose is decreased to below the current lowest clinical threshold and the resulting images still produce segmentations that are appropriate for input into AR applications. The application of denoising algorithms to the images resulted in increased artifacts and decreased bone density. Conclusions: The CT image quality that is required for successful AR auto-segmentation is lower than that which is currently employed in spine surgery. Future research is required to identify the specific, clinically relevant radiation dose thresholds.

Background: Spinal cord compression from degenerative cervical myelopathy is characterized by progressive loss of hand dexterity, alongside changes in the metabolite profiles in the brain and spinal cord. Correlating the changing metabolite profile with measures of dexterity following decompression surgery may assist in identifying which patients may benefit most from surgery. Methods: Thirty operative myelopathy patients consented to receive spectroscopy and GRASSP-M dexterity assessments both preoperatively and 6-weeks postoperatively. Magnetic resonance spectroscopy (TE=135) was performed in the motor cortex using a 3 Tesla Siemens MRI scanner at Robarts Research Institute. Spearman correlations were used to evaluate associations between metabolite levels and dexterity (p<0.05 was considered significant). Paired two-tailed Student t-tests were used to assess for postoperative changes in metabolite levels. Results: Postoperatively, we observed a statistically significant (p<0.05) negative correlation (r=-0.44) between the N-acetylaspartate-to-creatine ratio (NAA/Cr) and GRASSP-M dexterity scores. There was no significant difference in NAA, Cr, or NAA/Cr postoperatively. Conclusions: These findings demonstrate that patients with lower postoperative NAA/Cr usually have better recovery of dexterity. This link between the myelopathic metabolite profile and clinically meaningful dexterity values requires further investigation to understand the role of both NAA and Cr in mechanisms of postoperative recovery from myelopathy.

Background: Degenerative cervical myelopathy is characterized by progressive compression of the spinal cord resulting in debilitating loss of dexterity, independent ambulation, and sphincter control. Diffusion tensor imaging (DTI) has shown that, compared to healthy controls, myelopathy patients have decreased integrity of the corticospinal tracts and corpus callosum (Bernabeu-Sanz et al, 2020). Methods: Twenty-six myelopathy patients consented to cerebral diffusion tensor imaging (3 Tesla, 32 directions, b=1000) preoperatively, as well as 6-weeks, 12-weeks, and 6-months postoperatively. Average mean diffusivity (MD), fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) were measured in the corticospinal tracts, forceps major, and forceps minor. Results: Both MD and RD decreased from 6-12 weeks postoperatively in the right corticospinal tract. The forceps major of the corpus callosum showed an initial postoperative increase in MD followed by a subsequent increase in FA and decrease in RD 3-6 months postoperatively. The AD of the forceps major increased both immediately and 3-6 months postoperatively. Conclusions: Changes in microstructural integrity of the corticospinal tract and forceps major over the postoperative recovery period suggest a pattern of recovery in myelopathy patients. This study is the first to report postoperative DTI changes in myelopathy-relevant white matter tracts in the brain.

Background: Poorly-defined cases (PDCs) of focal epilepsy are cases with no/subtle MRI abnormalities or have abnormalities extending beyond the lesion visible on MRI. Here, we evaluated the utility of Arterial Spin Labeling (ASL) MRI perfusion in PDCs of pediatric focal epilepsy. Methods: ASL MRI was obtained in 25 consecutive children presenting with poorly-defined focal epilepsy (20 MRI- positive, 5 MRI-negative). Qualitative visual inspection and quantitative analysis with asymmetry and Z-score maps were used to detect perfusion abnormalities. ASL results were compared to the hypothesized epileptogenic zone (EZ) derived from other clinical/imaging data and the resection zone in patients with Engel I/II outcome and >18 month follow-up. Results: Qualitative analysis revealed perfusion abnormalities in 17/25 total cases (68%), 17/20 MRI-positive cases (85%) and none of the MRI-negative cases. Quantitative analysis confirmed all cases with abnormalities on qualitative analysis, but found 1 additional true-positive and 4 false-positives. Concordance with the surgically-proven EZ was found in 10/11 cases qualitatively (sensitivity=91%, specificity=50%), and 11/11 cases quantitatively (sensitivity=100%, specificity=23%). Conclusions: ASL perfusion may support the hypothesized EZ, but has limited localization benefit in MRI-negative cases. Nevertheless, owing to its non-invasiveness and ease of acquisition, ASL could be a useful addition to the pre-surgical MRI evaluation of pediatric focal epilepsy.

Background: Image-guided navigation is routinely used in spine surgery to improve placement of pedicle screws. However, most reports have relied on two-dimensional X-ray evaluation to determine accuracy of screw positioning. In this study, computed tomography (CT) and O-arm imaging enabled a detailed three-dimensional comparison of screw placement. The objective was to compare the accuracy of pedicle screw placement with intraoperative X-ray versus O-arm image-guided navigation. Methods: This was a retrospective analysis of image-guided pedicle screw placement in patients who underwent spinal instrumentation. Post-operative CT and O-arm imaging allowed grading of screw accuracy based on pedicle breaches. Clinical outcomes included patient and operative factors. Results: Pedicle screws were placed in 208 patients (1116 screws). Three-dimensional O-arm guidance was utilized for 126 patients, while the remainder underwent two-dimensional X-ray imaging and post-operative CT assessment. O-arm navigation was associated with improved pedicle screw accuracy: pedicle breaches were more likely to be low grade (odds ratio 2.84, p=0.001) and less likely to be medium grade (odds ratio 0.35, p=0.007) or high grade (odds ratio 0.31, p=0.025). Conclusions: This study provided a detailed comparison of surgical accuracy with X-ray versus O-arm guidance. Navigation with O-arm imaging is associated with benefits in spinal instrumentation, without impacting operative risks for patients.

Background: Most individual thalamic nuclei cannot be directly visualized on routine clinical MRI. Stereotactic targeting techniques are indirect, relying on histological atlases and electrophysiological recording. We investigate whether high-field MRI can directly visualize the thalamic nuclei in vivo and allow for analysis of disease-related changes. Methods: Thirty-two healthy individuals were imaged with 7T MRI at a resolution of 0.7mm3. To obtain a high-resolution composite image, these were registered across subjects and averaged together. Three thalamic structures closely integrated in seizure propagation, the anterior thalamic nucleus (ATN), mammillothalamic tract (MTT), and centromedian nucleus (CM) were manually segmented in a subset of healthy subjects and patients with temporal lobe epilepsy (TLE). Results: There is sufficient resolution within the thalamus at 7T for visualization of the ATN, CM, and MTT. In the small subset of 5 controls and 5 TLE patients examined, there was no significant difference (p>0.05) in volume or mean T1map for the three thalamic sturctures of interest. Conclusions: MRI at 7T provides a method of direct visualization of thalamic nuclei, uncovering substructures not previously identifiable in vivo. These advances will enable quantitative analysis of disease-related changes to these structures and improved clinical targeting as demonstrated in this initial ‘proof-of-concept’ subset analysis.

Background: Neurology Residency training in Canada is transitioning to competence based medical education (CBME) in July 2020 and the Royal College Neurology Specialty Committee has identified “providing consultation for and managing patients at outlying centers,” to be an entrustable professional activity (EPA). At Western, neurology telephone consultations, from outlying centres, are attended by both the resident and the staff Neurologist. This scenario provides the ideal situation for direct observation and immediate formative feedback. The resident’s performance is assessed using the ’TeleTool’ which utilizes an entrustment scale and has a short narrative portion. Methods: This mixed methods study aims to determine the reliability and validity of the ’TeleTool’ in assessing the performance of the telephone consultation by senior neurology residents. Informed consent was obtained from residents (9) and staff (7) involved. Scores on the entrustment scale and narrative comments were analysed. Results: Information on 30 encounters (involving 9 residents) was collected. TeleTool results demonstrated higher entrustment scores in PGY4 and PGY5 levels. Overall, ratings were consistent across the 7 consultants assessors. Conclusions: The TeleTool was reliable and valid in assessing competence in the telephone consultation and will be a useful tool for assessment of this EPA.

Background: The coronavirus 2019 pandemic has led to restructuring of health care systems and has subsequently had secondary effects on medical education. This study examines the impact on training of surgical residents in Canada. Methods: The study consisted of a 25-question survey for residents and a 22-question survey for program directors, which were distributed electronically through program administrators on July 3rd- July 11th, 2020. Questions sought to elicit residents’ current experiences and gain insight into methods by which to enhance future training. Results: 108 residents and 21 program directors, from various surgical specialties across Canada, completed the survey. Operative exposures were reported to be reduced by 25-100% and 39% of residents were redeployed. However, 89% of residents reported accessing academic half days virtually and 57% had additional online modules. Despite lost time, 100% of program directors confirmed that residents did not require training extensions. Concerns regarding training, personal health, employability and fellowships were raised. 55-70% of residents and program directors advocated for alternative educational courses, increasing elective time, utilizing simulation for assessment and flexibility in crediting different training experiences. Conclusions: Canadian surgical residents had a significant reduction in operative experiences during the pandemic. Moving forward, it will be important to find alternative educational experiences.

Background: Competence by Design (CBD), a new outcomes-based approach to medical education, has been recently introduced into neurosurgical programs across Canada. A cornerstone of this educational paradigm shift requires evaluation of residents’ performances of entrustable professional activities (EPAs). This study aimed to define Faculty expectations and markers of competence for resident EPA performances. Methods: Canada-wide survey of neurosurgical Faculty (NSF) with a 55-item online questionnaire referencing 15/45 available core neurosurgery EPAs. Results: Of the 52 respondents, majority believed that being able to perform safely (98%), effectively (92%) and independently (90%) and being able to adapt to contextual complexities of the case (88%) and unexpected events (88%) represented necessary qualities for demonstrating competence achievement of an EPA. Performing efficiently, without supervision and responding to rare events were all considered less important. On average, NSF believed that at least five separate assessments involving two or more different assessors were necessary for documenting competence achievement of each EPA. Proportion believing EPAs were representative of general neurosurgery competences varied significantly across all EPAs (p<0.00001) with >25% believing 5/15 EPAs required fellowship training. Conclusions: This study defined expectations and indicators of competent surgical performance and revealed a significant debate regarding perceived appropriateness of current EPAs for general neurosurgical training.

Background: Prior to its recent introduction into Canadian neurosurgical curriculum, Competence by Design (CBD) principles have been implemented across many international neurosurgical training programs for several years. As such, comparing other international competency-based educational frameworks and curricula can help anticipate, avoid or mitigate potential future challenges for Canadian neurosurgical trainees. Methods: A comparative web-based analysis of neurosurgical postgraduate medical education documents and resources provided by medical accreditation and regulatory bodies of Canada, the United States, the United Kingdom and Australasia, was performed. Results: All four countries varied considerably across four major curriculum-based themes: 1) general program structure; 2) overarching foundational competency frameworks; 3) types and numbers of performance assessments required and; 4) curricular learning outcomes. In particular, the expected progression and degree of competence required of neurosurgical residents when performing entrustable professional activities (EPAs) or defined tasks of neurosurgical practice, varied across all countries. Differences in types of neurosurgical EPAs and number of required assessments demonstrating a trainee’s competence achievement were also appreciated. Conclusions: This study revealed variations across competency-based neurosurgical curricula proposed by four international medical training regulatory bodies. Differences in types of EPAs and their required degree of competence achievement suggests potential disconnects between neurosurgical educational outcomes and actual medical practice.

Background: To improve accountability and reflect patient and societal needs, the Royal College of Physicians and Surgeons of Canada proposed Competence by Design (CBD) for all residency programs. This study compares neurosurgical patient values and expectations of their neurosurgeon to resident competences proposed by CBD curriculum. Methods: Semi-structured interviews of 30 neurosurgical patients and family members were recorded, transcribed and analyzed for themes. Results: Of the first 13 interviews (8 males, 5 females; median age 54), 10 had English as a first language, all completed post-secondary education, and 8 had a brain tumor. In addition to expecting excellent surgical skills and comprehensive medical knowledge, participants expected “good” neurosurgeons to be human (compassionate, empathetic, no ego), transparent communicators, accountable, passionate, collaborative, emotionally composed and highly intuitive. However, there were marked differences in minimum set of competencies required and the expectations of the thresholds to determine competence for neurosurgeons. Conclusions: Patient perspectives show commonalities and marked differences of the expected competencies compared to CBD and significant variability of the thresholds of competence. Further investigations should explore these themes in other specialties. The existing CBD curriculum will need to expand its framework to include humanistic values to improve public perceptions of competence.

Background: Microsurgical techniques remain a cornerstone of neurosurgical training. Despite this, neurosurgical microvascular case volumes are decreasing as endovascular and minimally invasive options expand. As such, educators are looking towards simulation to supplement operative exposure. We review a single institution’s experience with a comprehensive, longitudinal microsurgical simulation training program, and evaluate its effectiveness. Methods: Consecutive postgraduate year 2 (PGY-2) neurosurgery residents completed a one-year curriculum spanning 17 training sessions divided into 5 modules of increasing fidelity. Both perfused duck wing and live rat femoral vessel training modules were used. Trainee performance was video recorded and blindly graded using the Objective Structured Assessment of Technical Skills Global Rating Scale. Results: Eighteen participants completed 107 microvascular anastomoses during the study. There was significant improvement in six measurable skills during the curriculum. Mean overall score was significantly higher on the fifth attempt compared to the first attempt for all 3 live anastomotic modules (p<0.001). Each module had a different improvement profile across the skills assessed. The greatest improvement was observed during artery-to-artery anastomosis. Conclusions: This high-fidelity microsurgical simulation curriculum demonstrated a significant improvement in the six microneurosurgical skills assessed, supporting its use as an effective teaching model. Transferability to the operative environment is actively being investigated.

Background: Human induced pluripotent stem cell-derived neural stem cells (hiPS-NSCs) are a promising therapeutic approach to regenerate after spinal cord injury (SCI) as they can differentiate to myelinating oligodendrocytes, synaptically-active neurons, and supportive astrocytes. Unfortunately, most chronically injured patients develop ex vacuo microcystic cavitations which prevent regenerative cell migration and neurite outgrowth. QL6 is a novel, pH-neutral, biomaterial which can self-assembles into a supportive extracellular matrix (ECM)-like matrix in vivo. This work assesses QL6’s ability to support hiPS-NSC-based regeneration. Methods:In Vitro:hiPS-NSCs were extensively characterized by EDTA assay, qPCR, and immunocytochemistry(ICC), electron microscopy(EM) and neurosphere formation assays. In Vivo:Immunodeficient rats received clinically-relevant chronic C6-7 injuries. Animals were randomized: (1)vehicle, (2)hiPS-NSCs, (3)QL6, (4)QL6+hiPS-NSCs. All rats underwent treadmill rehabilitation and behavioural testing. A subset underwent single-cell RNA sequencing(scRNAseq). Results: hiPS-NSCs proliferated robustly on QL6(Ki67+/DAPI+; 29%vs6%; p<0.01). EDTA assay showed hiPS-NSC binding to QL6 to be driven by calcium-independent mechanisms. Importantly, QL6 enhanced adherent neurosphere formation. EM-imaging provided the first images of the hiPS-NSC/QL6 interaction. Behavioural assessments demonstrate synergistic improvements with combinatorial treatment. High-throughput scRNAseq differential gene expression analyses suggest QL6 is altering lineage signalling in the human graft post-transplantation. Conclusions: This work provides key proof-of-concept data that QL6 can support translationally-relevant human iPS-NSCs in traumatic SCI.

Background: Placement of an external ventricular drain is considered a simple yet fundamental procedure. Despite its wide practice, an inaccuracy rate of around 50% has been reported. In the trauma setting, targeting the ventricles with a blind freehand technique is challenging due to distorted anatomy. Failure to cannulate lead to multiple passes with a higher risk of complications. Methods: A retrospective study from a single institution was conducted using a trauma registry between March-2014 and March-2019 were included. Accuracy of EVD placement was determined using the Kakarla grading system Results: 224 TBI patients with total of 241 EVDs were performed, 211 met our criteria. Among them, Grade-1 (optimal placement) was achieved in 39.3%, Grade-2 (suboptimal in non-eloquent tissue) in 21.8% and Grade-3 (suboptimal in eloquent tissue) in 38.9%. A total of 74 EVDs were inserted in the intensive care unit, while 137 EVDs were inserted in the operating room. Our accuracy for ICU insertions was 50%, 25.7%, 24.3% for Grades1,2 and3 respectively, while our OR insertion accuracy was 33.6%,19.7%,and46.7% Conclusions: EVD is commonly performed, yet a substantial rate of inaccuracy is reported. This highly suggests the need to improve accuracy, possibly with the adjunct of image-guided techniques, to further optimize catheter placement

Background: Intoxicated patients injured in off road vehicle (ORV) crashes have higher rates of traumatic brain injury (TBI) and intensive care unit (ICU) admission, as well as prolonged ICU length of stay. This study evaluated the impact of alcohol intoxication on mortality among major TBI patients injured in off-road vehicle crashes. Methods: A retrospective analysis (2002-2014) of off-road vehicle injuries in Nova Scotia resulting in major TBI was performed. ORVs included ATVs, snowmobiles, and dirt bikes. A logistic regression model was constructed to test for in-hospital mortality and adjusted for age, Abbreviated Injury Scale (AIS) Head, Injury Severity Score, and blood alcohol concentration (BAC). Results: There were 176 drivers and passengers of off-road vehicles. Overall mortality was 28%. BAC testing was performed in 61% patients; 85% of pre-hospital deaths were BAC positive (mean BAC=31 ± 17.39 mmol/L) and 70% in-hospital deaths were BAC positive (mean BAC=26 ± 23.12 mmol/L). After adjusting for confounders, high injury severity and intoxication increased the likelihood of in-hospital mortality. Conclusions: These findings demonstrate that alcohol intoxication is a significant risk factor for mortality among off-road vehicle collisions; for every mmol/L change in BAC, there was a 10% increase in the chance of in-hospital mortality.

Background: Repetitive sub-concussive head impacts have been associated with changes in brain architecture and neurological symptoms. In this study, we examined the association between repetitive sub-concussive impacts, impact burden, and blood brain barrier (BBB) integrity in university football players. Methods: 59 university football players were followed over the 2019 season. Athletes with diagnosed concussion and those sustaining impacts that alerted a sideline impact monitor (relayed by ferroelectric helmet sensors) underwent dynamic contrast-enhanced MRI (DCE-MRI) within one week of injury/alert, and 4 weeks following initial incident. Results: Helmets recorded 2648 impacts over 48 cumulative hours. 8 concussions occurred during the 2019 season (2.82 per 1000 activity hours). On average, athletes with a diagnosed concussion had 55.3 impacts to the front sensor, compared to 14.1 in non-concussed athletes. Athletes who consented to DCE-MRI (n=5) had 10.78% BBB-D within a week of concussion/alert, and 6.77% BBB-D at 4-weeks. Conclusions: We show quantification of BBB integrity relative to head impact burden for the first time. This preliminary study highlights the potential of impact-detecting helmets to provide relevant impact characteristics and offers a foundation for future work on neurological consequences of repetitive sub-concussive impacts.

Background: Disruption in cerebrovascular reactivity following traumatic brain injury (TBI) is a known phenomenon that may hold prognostic value. Transcranial Doppler (TCD) has been employed to evaluate cerebrovascular reactivity following injury utilizing a continuous time-series approach. Methods: A systematically conducted scoping review of the literature on the association of continuous time-domain TCD based indices of cerebrovascular reactivity, with outcomes following moderate and severe TBI was performed. Multiple databases were searched from inception to November 2020 for relevant articles. Results: Thirty-six relevant articles were identified. There was significant evidence supporting an association with continuous time-domain TCD based indices and functional outcomes following TBI. Physiologic parameters such as intracranial pressure, cerebral perfusion pressure, Carbon Dioxide (CO2) reactivity as well as more established indices of cerebrovascular reactivity have all been associated with these TCD based indices. The literature has been concentrated in a few centres and is further limited by the lack of multivariate analysis. Conclusions: There is a substantial body of evidence that cerebrovascular reactivity as measured by time-domain TCD based indices have prognostic utility following TBI. The literature supports some associations between these indices and cerebral physiologic parameters. Further validation in multi-institution studies is required before these indices can be widely adopted clinically.

Background: Clinical guidelines recommend MAP maintenance at 85-90 mmHg to optimize spinal cord perfusion post-SCI. Recently, there has been increased interest in spinal cord perfusion pressure as a surrogate marker for spinal cord blood flow. The study aims to determine the congruency of subdural and intramedullary spinal cord pressure measurements at the site of SCI, both rostral and caudal to the epicenter of injury. Methods: Seven Yucatan pigs underwent a T5 to L1 laminectomy with intramedullary (IM) and subdural (SD) pressure sensors placed 2 mm rostral and 2 mm caudal to the epicenter of SCI. A T10 contusion SCI was performed followed by an 8-hour period of monitoring. Axial ultrasound images were captured at the epicenter of injury pre-SCI, post-SCI, and hourly thereafter. Results: Pigs with pre-SCI cord to dural sac ratio (CDSR) of >0.8 exhibited greater occlusion of the subdural space post-SCI with a positive correlation between IM and SD pressure rostral to the injury and a negative correlation caudal to the epicenter. Pigs with pre-SCI CDSR <0.8 exhibited no correlation between IM and SD pressure. Conclusions: Congruency of IM and SD pressure is dependent on compartmentalization of the spinal cord occurring secondary to swelling that occludes the subdural space.

Background: Neurotrauma accounts for over 24 000 hospitalizations annually in Canada. Among those affected, Indigenous peoples are disproportionately impacted. The goal of this scoping review is to identify factors underlying these disparities. Methods: A scoping review was conducted to collect papers pertaining to neurotrauma in Indigenous populations of Canada. Using MEDLINE, 676 articles were screened with MeSH terms including ‘Indigenous’, ‘spinal cord injuries’, ‘brain injuries, traumatic’ and ‘Canada’ as of April 2021. Results: Studies report over twice the incidence of traumatic brain injury and traumatic spinal cord injury in Indigenous populations compared to non-Indigenous populations. The burden of neurotrauma is attributable to infrastructure disparities in rural communities and reserves, elevated rates of substance use and violence, and inequities in treatment and rehabilitation following injury. These issues are deeply rooted in the trauma endured by Indigenous peoples through the course of Canadian history, owing to government policies that severely impacted their socioeconomic conditions, culture, and access to healthcare services. Conclusions: Systems-level interventions guided by Indigenous community members will help to address the disparities that Indigenous peoples face in the care and rehabilitation of neurotrauma. This study will inform further research of culturally appropriate approaches to reduce neurotrauma burden among Indigenous peoples.

Background: Cerebral aneurysms are an unusal cause of epilepsy. To date, several groups have reported temporal lobe seizures caused by aneurysms projecting into the parahippocampal gyrus. Given the low incidence of posterior cerebral artery aneurysms, they are a very rare cause of temporal lobe seizures. Methods: Here, we report a rare case of temporal lobe epilepsy caused by an unruptured aneurysm. We also present a review of the literature yielding two similar cases. Results: A previosuly well 56 year old male presented to a neurologist with symptoms consistent with temporal lobe epilepsy. He was started on carbamzepine and underwent imaging and neuropsychological assessments. An MRI suggested the existance of a 7mm posterior cerebral artery aneurysm arising from the P2 segment of the posterior cerebral artery and projecting into the parahippocampal gyrus. This was also confirmed with CT angiography and the patient elected to have the aneurysm clipped. Conclusions: Temporal lobe epilepsy is an uncommon presentation for unruptured cerebral aneurysms. We report a rare case wherein a laterally pointing PCA aneurysm was buried in the posterior parahippocampal gyrus. This aneurysm had caused perifocal gliosis leading to stereotyped seizures. Post-operatively, the patient has been seizure free.