Background: Studies of deep brain stimulation (DBS) require accurate electrode localization and image registration. We used anatomical fiducials to investigate localization and registration errors in patients who underwent subthalamic nucleus (STN) DBS for Parkinson’s disease (PD). Methods: We conducted a retrospective analysis of patients who underwent bilateral STN DBS for PD. Pre and post operative MRI scans were non-linearly normalized to a standard template (MNI152NLin2009bAsym). Four raters localized DBS electrodes (Lead-DBS), the anterior commissure (AC) and posterior commissure (PC). Errors between rater localizations were calculated (fiducial localization error; FLE). We transformed AC and PC coordinates from template to patient space to calculate the fiducial registration error (FRE)Results: Ninety-nine patients were analyzed, with a median FLE of 0.76mm, 0.74mm, 0.71mm and 0.66mm for the right electrode, left electrode, AC and PC respectively (no significant difference, Wilcoxon sign rank). The median FRE was 1.59mm for AC and 1.21mm for PC, significantly higher than FLE at those coordinates (Wilcoxon sign rank, p<0.001). Conclusions: Raters can accurately localize DBS electrodes, AC and PC from clinical images with sub-millimetric accuracy. Higher FREs at AC and PC suggested registration errors may contribute more than localization errors to electrode uncertainty in a common space.

Background: The competency-based medical education (CBME) model has been recently implemented in spinal neurosurgical and orthopedic residencies. This model is grounded on entrustable professional activities (EPAs) that allow the assessment of clinical milestones. Integrating quantitative metrics to evaluate procedural competencies could refine the assessment’s scope. This survey, administered to program directors (PDs), aims to evaluate the current state and anticipated needs for quantitative evaluation to develop innovative assessment techniques. Methods: We surveyed 32 PDs of neurosurgical (N=14) and orthopedics (N=16) programs with a spine service via RedCap. We collected information on the programs’ characteristics. We inquired about existing assessment methods and the perceived values of developing quantitative metrics to assess spinal technical competencies using thirteen questions. Results: The response rate was 53%. All programs use EPAs to assess procedural competencies through direct observation in the operation room. One surgical program employed quantitative metrics for examination. Four PD valued the profitability of quantitative evaluation methods in a clinical or simulatory context. Conclusions: The use of quantitative metrics to assess spinal surgical competencies in Canadian neurosurgical and orthopedic residency programs is seldom. Despite its underutilization, PDs acknowledge the potential for quantitation to improve the accuracy and reliability of CBME assessments in both simulated and clinical settings.

Background: Cerebrovascular reactivity has been identified as an important contributor to secondary injury following moderate to severe traumatic brain injury (TBI). “Gold-standard” intracranial pressure (ICP) based indies of cerebrovascular reactivity are limited by their invasive nature poor spatial resolution. Near infrared spectroscopy (NIRS) based indices of cerebrovascular reactivity are minimally invasive and have improved spatial resolution. In this study, classical machine-learning algorithms are leveraged to better characterize the relationship between these indices. Methods: High-resolution physiologic data was collected in a cohort of adult moderate to severe TBI patients. From this data both ICP and NIRS based indices of cerebrovascular reactivity were derived. Utilizing Agglomerative Hierarchical Clustering (AHC) and Principal Component Analysis, the relationship between these indices in higher dimensional physiologic space was examined. Results: A total of 83 patients with 314,395 minutes of unique and complete physiologic data was obtained. Through AHC and PCA there was higher order clustering between NIRS and ICP based indices, separate from other physiologic parameters. Conclusions: NIRS and ICP based indices of cerebrovascular reactivity relate to one another in higher dimensional physiologic space. NIRS based indices of cerebrovascular reactivity may be a viable alternative to ICP based indices.

Background: Cerebrovascular reactivity is an important contributor to secondary injury following traumatic brain injury (TBI). The poor spatial resolution and invasive nature of “Gold-standard” intracranial pressure (ICP) based indies of cerebrovascular reactivity limit their use. Near infrared spectroscopy (NIRS) based indices of cerebrovascular reactivity are minimally invasive and have improved spatial resolution. The precise relationship between NIRS and ICP based indices is quantified utilizing times series analysis and advanced statistical techniques. Methods: High-resolution physiologic data was collected in a cohort of adult moderate to severe TBI patients at a single quaternary care site. From this data both ICP and NIRS based indices of cerebrovascular reactivity were derived. The times series structure of these indices was determined and used to correct for autocorrelation in a linear mixed effects model of ICP based indices from NIRS based indices of cerebrovascular reactivity. Results: A total of 83 patients were included in this study. Times series analysis coupled with mixed effects modeling was utilized to examine the relationship between ICP and NIRS based indices of cerebrovascular reactivity. Conclusions: Times series analysis coupled with mixed effects modeling allows for a more complete understanding of the relationship between ICP and NIRS based indices of cerebrovascular reactivity in the setting TBI.

Background: Penetrating head injury secondary to crossbows is a rare encounter in neurosurgical practice with only few cases reported in the literature. Methods: Chart review and literature review. Results: A 31-year-old man with a previous psychiatric history sustained a self-inflicted injury using a crossbow he bought from a department store. The patient arrived neurologically intact. He was not able to verbalize due to jaw fixation with the arrow. The trajectory of the object showed an entry point at the floor of the oral cavity and an exit through the calvarium just off the midline. The oral and nasal cavities, along with the palate and the skull base, and the left frontal lobe were all breached (figure). No vascular injury was identified on imaging (figure). The arrow was surgically removed in the operating room after establishing an elective surgical airway. A planned delayed CSF leak repair was performed. The patient made a substantial recovery and was discharged home in good status. Conclusions: - Multidisciplinary team is key.

Vascular imaging should be done pre and post-intervention.

Surgical approach is determined by the trajectory.

Psychiatric illness and access to weapons are major risk factors.

Elective surgical airway might be indicated.

Background: Cortical spreading depolarization (CSD) is associated with poor outcomes following traumatic brain injury (TBI). Here we aimed to: (1) determine the effect of NMDA-receptor antagonism on CSDs in healthy and TBI animals in vivo; and (2) conduct a randomized pre-clinical trial (RCT) of memantine for prevention neurological decline following repetitive mild TBI (rmTBI). Methods: Rodents received either one moderate (n = 23) or four daily mild (rmTBI; n = 30) head impacts (weight drop). Sham animals received brief anesthetic without TBI (n = 40). 93 animals underwent cranial window surgery with electrocorticographic (ECoG) monitoring and electrically triggered CSDs. Ketamine (100uM topical or 25 mg/kg IP) and memantine (10 mg/kg IP) were tested in vivo. An RCT was conducted (N=31) using memantine (10 mg/kg) or saline (2.5 cc/kg) for rmTBI with daily neurobehavioural testing. Results: In TBI animals, ketamine or memantine inhibited CSDs in 44-88%, and 50-67% of cases, respectively. Near-DC/AC-ECoG amplitude was reduced by 44-75% and 52-67%, and duration by 39-87% and 61-78%, respectively. RCT animals that received memantine had higher mean neurological scores (9.27 (SD 3.08) vs. 5.56 (SD 3.05), p< 0.001) vs. saline. Conclusions: Memantine suppressed CSDs following TBI, in vivo. In a pre-clinical RCT of rmTBI, memantine prevented neurological decline.

Background: Chronic subdural hematoma (CSDH) is one of the most encountered conditions seen in neurosurgery. Although mainstay treatment of cSDH has been burr hole drainage, no consensus yet exists on optimal anesthesic technique for surgical treatment between general (GA) and local (LA) anesthesia. Methods: A search was conducted in MEDLINE (1946 to November 11, 2022), Embase (1974 to November 11, 2022), and PubMed (up to November 11, 2022). We followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to systematically screen studies. Results: Our literature search identified 521 studies, out of which 20 were included. There were a total of 1750 patients who underwent CSDH drainage under LA. The weighted mean age was 71.0 years, and 27.1% were female. Postoperative complication rate was significantly lower in the LA group (odds ratio 0.44, p = 0.004). The mean operative time (mean difference -29.28 minutes, p <0.0001) and length of admission (mean difference -1.58 days, p = 0.0002) were significantly shorter in the LA group. Conclusions: In this meta-analysis, LA shows benefits in shorter operative time, shorter admission length, and fewer postoperative complications. This makes local anesthesia a less invasive alternative to general anesthesia especially in elderly patients.

Background: Little data exists on the impact of metabolic acidosis in aneurysmal subarachnoid hemorrhage (aSAH). Given its detrimental effects in critically ill patients, we inquired whether in patients with aSAH, metabolic acidosis (bicarbonate <22mmol/L) was associated with an increased risk of worse outcomes at 3 months (mRS >2). Methods: We performed a retrospective analysis of the CONSCIOUS-1 randomized control trial dataset including all patients who had at least three bicarbonate levels drawn. Bivariate and multivariate logistic regression models were used to assess for independent relationship between metabolic acidosis and functional outcome at 3 months. Delayed cerebral ischemia (DCI) was assessed for potential effect modification. Results: Three hundred and nineteen patients were included in our analysis. There was no difference in the proportion of poor outcome between those with or without metabolic acidosis on bivariate analysis (OR=1.022, p=0.949). However, amongst individuals who develop DCI, there was increased odds of unfavorable outcome when patients developed metabolic acidosis (OR=7.588, p=0.023). Conclusions: Individuals who develop delayed cerebral ischemia may benefit from having their bicarbonate level carefully monitored. More studies are needed to determine how the development of metabolic acidosis can be mitigated, and whether its prevention leads to improved outcomes.

Background: Neuropsychological outcomes are an important component of the morbidity after aneurysmal subarachnoid hemorrhage (aSAH). Data on the relationship between delayed cereberal ischemia (DCI) and neuropsychological outcomes remains sparse. We herein assess the relationship between DCI and neuropsychological outcomes, as measured by the Montreal Cognitive Assessment score (MoCA) at 90 days in patients with aSAH. Methods: We performed a post-hoc analysis of the Nimodipine Microparticles to Enhance Recovery While Reducing Toxicity After Subarachnoid Hemorrhage (NEWTON-2) clinical trial. Patients were grouped based on whether they developed delayed cerebral ischemia. We assessed the relationship between MoCA scores and DCI with Student’s t-test and regression modeling. Age, sex, history of hypertension, and WFNS grade were included as covariates in the model. Results: Two-hundred and fifteen patients were included in our analysis. Mean MoCA score at 90 days in our population was 22. Mean MoCA scores were significantly lower in patients who developed DCI compared to those who did not (23.7 vs 18.4, p<0.001). Age, WFNS grade, and development of DCI were independently associated with MoCA scores in the regression model (p < 0.05). Conclusions: DCI is a predictor of decreased neuropsychological outcomes in aSAH survivors and may contribute to the morbidity burden in this population.

Background: Cerebral vasospasm is a feature of delayed cerebral ischemia that can occur after subarachnoid hemorrhage from cerebral aneurysm rupture. CTa is the universal first line diagnostic modality (sensitivity 79.6%, specificity 93.1%). We aim to determine whether specific vasospasm-associated radiographical and clinical features predicts cerebral vasospasm with comparable accuracy. Methods: Our cohort included 403 patients between 2006-2019. We used clinical predictive features including: day since rupture, transcranial doppler Lindegaard ratio, MCA velocity, ICA velocity, physical examination, and radiographical predictive features including: volume of hematoma, artifact, aneurysm, as our training dataset with true positives being digital subtraction angiography confirmed vasospasm. We used a decision-tree classifier from Scikit-learn library for training and testing of the model. Results: Our model trained on clinical and radiographical predictive features achieved sensitivity 93%, specificity 67%, F1 score 0.88. When using only radiographical features, we reached sensitivity 90%, specificity 55%, F1 score 0.83. When using only clinical features, we reach sensitivity 70%, specificity 93%, F1 score 0.87. Conclusions: We show that our vasospasm predictive model achieves adequate sensitivity, specificity, and F1 scores when compared to CTa. With further increase in dataset and fine-tuning of hyper-parameters, it is possible that our model may be used to optimize the vasospasm management pipeline.

Background: The pathophysiology of internal carotid artery (ICA) blister aneurysms is poorly understood. Our goal is to investigate the hemodynamic factors contributing to their formation and progression using computational fluid dynamics. Methods: We developed software allowing 3D reconstruction of type I and II blister aneurysms (Bojanowski et al., 2015) from ICA angiography. Kinematic blood flow data was obtained using a finite volume solver. We compared the wall shear stress distribution (WSS) of the healthy arterial wall under various blood pressure conditions. Results: WSS was maximal on the dorsal wall of the supraclinoid segment of the ICA at the distal part of the future site of the aneurysm sac, suggesting that the aneurysm sac initially develops in a retrograde fashion. The WSS gradient (WSSG) was maximal at both the proximal and distal boundaries of the bulging aneurysm. Hypertension exponentially exacerbates the WSS distribution. Very low WSS associated with a high WSSG at the proximal part of the aneurysm sac could explain the extension of the hemorrhage proximal to the forming blister. Conclusions: WSS and its gradient participate in the formation and progression of blister aneurysms of the supraclinoid segment of the ICA. Increasing blood pressure contributes exponentially to the formation of blister aneurysms.

Background: We describe a patient with recurrent subarachnoid hemorrhage (SAH) secondary to Chiari 1 malformation. Methods: A retrospective review of the clinical chart was performed. Results: A previously healthy female in her 70’s presented with worst headache of life. CT demonstrated 4th ventricular hemorrhage with SAH extending into the bilateral cerebellomedullary fissures. CTA did not show a vascular etiology and patient was discharged home. Incidental note was made of a right persistent trigeminal artery. The patient then represented 2 weeks later with worst headache of life and decreased level of consciousness. CT demonstrated extensive SAH extending into the 3rd and 4th ventricles. CTA and diagnostic cerebral angiogram did not show a vascular etiology. MRI brain/C-spine revealed Chiari 1 malformation. An external ventricular drain was placed but could not be weaned. She underwent suboccipital craniectomy with C1 laminectomy. Intraoperatively, there was a prominent dorsal spinal vein that appeared under tension as it pierced the arachnoid membrane and subsequently entering the dura as a rudimentary occipital sinus. This vein was coagulated and divided. The patient recovered well and was at neurological baseline at 6 month follow-up. Conclusions: This is the first reported case of recurrent SAH secondary to Chiari 1 malformation.

Background: Basilar fenestration is a rare congenital anomaly. When present, it is commonly found at the proximal portion of the artery near the vertebrobasilar junction. Methods: This is a case report of a ruptured basilar fenestration aneurysm in a 47-year-male successfully treated with endovascular coiling. Results: A 47-year-old male presented with sudden onset headache, neck pain, blurry vision, nausea, vomiting, and diaphoresis. Cerebral angiogram revealed a saccular basilar fenestration aneurysm located at the vertebrobasilar junction measuring 3.1 x 2.6 x 3.4 mm with a 2.3 mm neck. Multiple coils were placed including Target 360 Nano 2mm x 4 cm (Stryker, Kalamazoo, MI, US), Target 360 Nano 1.5 mm x 2 cm (Stryker, Kalamazoo, MI, US), and Target Helical Nano 1.5 mm x 1 cm (Stryker, Kalamazoo, MI, US). A repeat angiogram revealed complete exclusion of the aneurysm with preservation of both vertebral arteries. Conclusions: A literature review was conducted on basilar fenestration aneurysms which included 158 patients from 39 studies. Overall, complete exclusion of the aneurysm was achieved in 75.8% of cases, with 22.4% of cases having residual flow and 1.8% of cases with unreported exclusion status.

Background: The efficacy of decompressive craniectomy (DC) for patients with intracranial hypertension secondary to aneurysmal subarachnoid haemorrhage (aSAH) remains unclear. Methods: We identified aSAH patients who underwent DC following microsurgical aneurysm repair from a prospectively maintained cerebrovascular registry and compared their outcomes with a propensity-matched cohort who did not. Results: A total of 45 aSAH patients underwent DC between 01/09/2011 and 20/07/2020 and were compared with 45 propensity-matched controls. There were no differences in patient age (p=0.48), gender (p=0.53) or the proportion requiring endovascular vasospasm treatment (p=1.00). However, patients in the DC subgroup had a higher mean WFNS grade (3.47±1.53) compared with matched controls (2.8±1.25, p=0.03). Patients treated with DC had a higher rate of inpatient mortality (20.00% vs 0.00%, p=0.0025), unfavourable outcome (mRS≥4) at 1st (42.22% vs 11.11%, p=0.0016) and final (31.11% vs 2.94%, p<0.001) follow-up, and NIS-Subarachnoid Hemorrhage Outcome Measure positivity (40.00% vs 13.33%, p=0.0079). They also had a higher median mRS at 1st [3(2–4) vs 1(1–2), p<0.001], and final [2(1–4 vs 1(1 (0–2), p<0.001] follow-up. Conclusions: Patients treated with DC fared worse at every endpoint, which was disproportionate to the difference in presenting WFNS grade. These data do not support the use of DC following microsurgical clipping of a ruptured aneurysm.

Background: Accurate outcome prediction among patients with aneurysmal subarachnoid haemorrhage (aSAH) has remained elusive. We aimed to identify outcome predictors and develop a model to guide clinicians and the families of patients who are being considered for microsurgical repair of a ruptured aneurysm. Methods: We identified 246 consecutive patients with aSAH who underwent microsurgical clipping of the culprit aneurysm between 01/09/2011 and 20/07/2020. Independent predictors of outcome were identified using logistic regression and an outcome prediction model was developed. Results: Age>55 (OR3.35, 95%CI 1.06–10.56, p=0.04), high-grade aSAH (WFNS≥4) (OR7.82, 95%CI 2.66–22.98, p<0.001) and midline shift of ≥5mm (OR10.35, 95%CI 3.22–22.23, p<0.001) were all associated with unfavourable outcome (mRS≥4) at a mean of 87.27 (±53.40) days after ictus. Age>55 was also associated with inpatient mortality (OR4.98, 95%CI 1.83–13.54, p=0.002) and unfavourable outcome at final follow-up (OR3.76, 95%CI 1.26–11.20, p=0.002). Furthermore, midline shift of >5mm was significantly associated with inpatient mortality (OR5.55, 95%CI 1.74–17.64, p=0.004) and unfavourable outcome at final follow-up (OR9.71, 95%CI 3.25–29.04, p<0.001). Conclusions: Older age, poorer presenting WFNS grade and increased mass effect are all associated with poorer outcome among patients undergoing microsurgical clipping of a ruptured aneurysm. These data have been used to construct an outcome prediction model for these patients.

Background: Women continue to represent a minority of the neurosurgery workforce in Canada. We herein aim to provide an update of the current Canadian landscape to gain a better understanding of the factors contributing to this disparity. Methods: Chain-referral sampling, interviews, personal communications, and online resources were used as data sources. Online survey results obtained from women attending neurosurgeons across Canada were also utilized. Quantitative analyses were performed, including summary and comparative statistics. Qualitative analyses of free-text responses were performed using axial and open coding. Results: We observe a positive trend in the incoming and graduating of female residents across the country, although this trend is lagging compared to other surgical specialties. The proportion of women in active practice remains low. Positive enabling factors for success include supportive colleagues and work environment (52.6%), academic accomplishments (36.8%), and advanced fellowship training (47.4%). Perceived barriers reported included inequalities regarding career advancement opportunities (57.8%), conflicting professional and personal interests (57.8%), and lack of mentorship (36.8%). Conclusions: Women continue to represent a small proportion of practicing neurosurgeons across Canada. Our work highlights several key factors contributing to the low representation of women in neurosurgery and identifies actionable items that can be addressed by training programs and institutions.

Background: Various challenges and innovations have led to the evolution of neurosurgery in the ASEAN region. This has increased interest among neurosurgeons to publish research papers for the past years. The study aims to compare the publication trend, and topic trend on research in the region using scientometric techniques. Methods: Publications from Web of Science (WoS) using the keywords “neurosurgery” OR “neurological surgery.” were obtained. Results only included English articles published from ASEAN countries. Publication, citation, collaboration, and text-co-occurrence analysis were done using WoS and VOSViewer. Results: 1951 articles published between 1996 to 2022 were analyzed. The ASEAN countries’ productivity are: Singapore (34.07%), Thailand (21.66%), Indonesia (15.25%), Malaysia (14.72%), Philippines (5.99%), Vietnam (5.15%), Cambodia (1.78%), Myanmar (1.16%), Brunei (0.21%). Singapore, Thailand, Malaysia, and Indonesia were the top research collaborators. Publications have clusters of co-occurring keywords: (1) seizure, aneurysm, pain; (2) traumatic brain injury, mortality, functional outcome; (3) technology, application; (4) survey, training; (5) glioblastoma, brain metastases, chemotherapy. Conclusions: Trend in publications support the growing importance of neurosurgery. Variations in publications are attributed to differences in research interest, training, technology and culture between countries. These are relevant to aid in future capacity-building projects, research agendas, policy guidelines, and collaboration between countries, to improve research production.

Background: Spinal meningiomas are intradural extramedullary tumors that account for 25–46% of all primary spinal tumors. A growing body of literature suggests that the extent of resection significantly affects the recurrence rate of spinal meningiomas and that Simpson grade II resection may not be as adequate as previously thought. Dura Splitting Technique (DST) can be used with no major perioperative complications. Methods: Retrospect review of six cases of spinal meningiomas where DST was used. The patients ranged in age at presentation from 38 to 80 years. All presented with symptoms including gait unsteadiness and lower limbs weakness. Spinal MRI was used to establish the diagnosis. All of the tumors were located ventral or ventrolateral to the spinal cord. Results: DST was applying to spinal meningioma cases,complete tumor resection by separating the involved dura into inner and outer layer. Preserving the dura outer layer and avoiding the need for dural graft reconstruction and CSF leak. A total of six cases, four in thoracic spine and two in cercical spine one anterior and one posterior, all four cases had no reported surgical complications or tumor recurrenc. Conclusions: We confirm that DST is safe and a superior method in the treatment of spinal meningiomas.

Background: Endoscopic third ventriculostomy (ETV) has become a treatment of choice for adults with clinically significant chronic obstructive hydrocephalus (COH). We evaluated the impact of ETV on cognition and gait in adults with COH. Methods: We retrospectively analyzed prospectively collected data from patients who underwent ETV as primary treatment for COH. Cognitive testing using the Montreal Cognitive Assessment (MoCA) and Symbol Digit Modalities Test (SDMT) was obtained pre-ETV at three months and one year postoperatively. Gait velocity was assessed using a 10-m walk test at each time point. Results: A total of 51 patients were identified. The mean age was 55±1 years, and 45% of patients were women. Baseline MoCA was 22.6±3.1, which improved to 25.7±3.0 and 26±3.4 at three months and one year, respectively (p<0.001). Half of the patients had a normal MoCA score post-ETV (IQR 26-27 at one year, p<0.001). Gait velocity was significantly improved at three months and 1-year post-ETV (p=0.0036). The cognitive and gait improvement one year after ETV was clinically significant. Conclusions: Cognition and gait improved at three months; results were sustained at 12 months post-ETV in adult patients with COH. ETV is an efficacious surgical consideration in this population.

Background: Following craniotomy, there is widespread agreement that post-operative neurological impairments require specialized evaluation to evaluate fitness to drive. However, for patients who had a craniotomy and do not have neurological deficits or known seizures, there is less consensus as to when return to driving is safe. In this study, we aim to review existing guidelines regarding driving post-craniotomy and assess the current practices for post-craniotomy recommendations in Canada. Methods: Our study has three components: 1) systematic review of existing guidelines for return to driving after cranial procedure; 2) review of primary evidence (cohort studies) regarding seizure risk following a craniotomy, depending of the underlying pathology; 3) online questionnaire distributed to Canadian neurosurgeons by the Canadian Neurosurgery Collaborative (CNRC) network. Results: Our systematic review unveiled various sets of guidelines for driving after a craniotomy. For instance, UK Driving and Vehicle Licensing Agency writes into law specific guidelines for return to driving varying based on underlying pathology. Their results were drawn from large cohort studies measuring the occurrence of post-operative seizures after craniotomy for a variety of conditions. The questionnaire is currently being distributed to Canadian neurosurgeons. Conclusions: Our study lays the first steps towards the development of Canadian guidelines for return to driving post-craniotomy.