Background: Neurofibromatosis 1 and 2 (NF1 and NF2) are autosomal dominant genetic disorders caused by mutations in tumour suppressor genes. Methods: We conducted a systematic review of the incidence and prevalence of NF1 and NF2 in OVID Medline, OVID Embase, Web of Science, and Cinahl. We included studies until February 19, 2021, that identified cases based on established criteria. Studies were appraised for quality using the Joanna Briggs Institute Prevalence Critical Appraisal tool. Pooled incidence and prevalence rates were estimated through meta-analysis. Results: Of 1,936 studies, 1,866 were irrelevant after title and abstract screening. Sixteen of 69 studies with full text assessment were included for full review: 13 regarding NF1 and 6 regarding NF2. Incidence rates for NF1 and NF2 ranged from 1/11,494 to 1/1,871 and 1/62,185 to 1/33,000 respectively. Prevalence rates for NF1 and NF2 ranged from 1/6,238 to 1/1,001 and 1/600,000 to 1/56,161 respectively. Meta-analysis will be presented at the conference. Conclusions: An accurate estimate of the incidence and prevalence of NF1 and NF2 will offer more insight into health resource allocation. Increased funding and resources for the development of early diagnostic and treatment tools for NF1 and NF2 may improve the quality of life of patients.

Background: Objective markers of disease progression are needed for patients with multiple sclerosis (MS). Increased randomness in neural networks is hypothesized to be an important cause of morbidity that can be objectified using graph theory. Methods: We use voxel-based structural similarity determined from T1-weighted MRI scans of 23 patients with MS receiving autologous stem cell transplant (ASCT) to compute cortical covariance network parameters. We examine associations between measures of cortical integration or segregation and biochemical/clinical measures of cortical health or function using Spearman correlation coefficients. P<0.05 was considered significant. Results: Path length increase was associated with markers of greater inflammation (ρ=0.56,P<.046) at baseline and reduced Naa/Cr ratio (P<.041) at 12 months. Reduced lambda was associated with markers of greater grey matter atrophy (ρ=0.55,P<.019) after 12 months and lower cognition (ρ=0.56,P<.008) at 12 months. Reduced clustering was associated with higher neurofilament (ρ=-0.68,P<.010) at baseline, greater white matter atrophy (ρ=0.62,P<.006) after 12 months, lower 2-second PASAT performance (ρ=0.56,P<.011) at baseline, and reduced Naa/Cr ratio (P<.001) at 12 months. Conclusions: Reduced cortical integration and segregation (random network features) co-occur with unfavourable markers of cortical health and function in patients with MS receiving ASCT. Network features show promise as important longitudinal markers of patient status and progression.

Background: Approximately 20-40% of patients with non-small cell lung cancer (NSCLC) will develop brain metastases (BM). The aim of this study was to investigate if Epidermal Growth Factor Receptor (EGFR) status of NSCLC alters the radiological appearances of BM. Also to compare differences in imaging features of BM occurring from EGFR-mutated NSCLC during treatment with Tyrosine Kinase Inhibitors (TKI) versus prior to treatment. Methods: A retrospective study was performed over a 5 year period of all patients with histologically proven NSCLC with BM and known EGFR status. 72 patients met the inclusion criteria. Radiological features were reviewed as well as number, size and location of BM. Results: 18/72 patients had EGFR-mutated NSCLC and of these 9 presented with BM while on TKI treatment. Patients with EGFR-mutated NSCLC had statistically significant higher occurrence of multiple BM (p=0.029) and BM in a central location (p=0.027). BM that occurred during TKI treatment appeared smaller and with minimal surrounding oedema. Conclusions: Given the propensity for multiple BM in EGFR-mutated NSCLC, vigilant imaging follow up would need to be considered. BM presenting while on TKI were more subtle, especially on Computed Tomography (CT), therefore careful follow up with Magnetic Resonance Imaging (MRI) may be required.

Background: The aim of this study is to investigate the differences in the radiological appearances of brain metastases (BM) in metastatic melanoma (MM) relative to BRAF mutation status. As well as to compare imaging differences in BM that occur prior to starting and during systemic therapy. Methods: A retrospective study was done over a 5 year period. Patients with MM with BM and known BRAF status were identified. 38 met the inclusion criteria. Imaging features on both Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) were reviewed. Results: Irrespective of BRAF mutation status, BM in MM tended to have a peripheral location with 30/38 cases having BM in the cerebral cortex. BRAF positive MM had a higher frequency of irregularly enhancing BM on CT and higher occurrence of BM showing high T1 signal on MRI. BM found during systemic treatment, regardless of BRAF status, showed less surrounding oedema, were smaller and harder to spot on CT. Conclusions: Understanding imaging features based on genetics could inform future management. The subtle features of BM on CT during systemic therapy means careful follow up with MRI may be indicated to confirm the diagnosis and to more accurately assess the burden of brain disease.

Background: Vascular closure devices (VCDs) are routinely used in both neurovascular and vascular interventional procedures. The purpose of our study was to assess the safety and efficacy of the VCDs for diagnostic and therapeutic neurovascular and vascular procedures. Methods: The study was approved by the University of Manitoba research ethics board. A retrospective review was conducted of the database between January 2017 and December 2019. The data was collected from the Picture Archiving and Communication System (PACS) and collected in an excel spreadsheet. Patient demographics and clinical information was collected. Descriptive statistics and chi-squared tests were performed using STATA 13 software. A p<0.05 was considered significant. Results: VCD was used in a total of 2072 patients. VCDs were successfully deployed in 94% with 6% failure. Immediate perioperative complications were seen in 6.2% patients. The complication rates were significantly (p=0.025) associated with the type of procedure. Complications were seen significantly (p=0.044) higher in outpatients compared to inpatients and those from emergency room. Conclusions: VCDs were successfully deployed in 96VCDs were successfully deployed in 94% of the patient with 6% perioperative complications. Most of the complications were minor and complications were more commonly associated with outpatients procedures and with diagnostic vascular procedures.

Background: A basic understanding of localization for a given set of focal neurological deficits is essential for accurate acquisition and interpretation of neuroimaging. Relying on often-limited clinical information, neuroradiologists must choose the most appropriate imaging modality and tailor a study to best identify the culprit lesion to allow for accurate interpretation. Methods: A multiple-choice quiz was designed including clinical vignettes localizing to lesions within the central (CNS) and peripheral nervous systems (PNS). The quiz was pilot-tested and refined before distribution as an electronic survey to practicing neuroradiologists and fellows within newsletters from the American Society for Neuroradiology and Canadian Neurological Sciences Federation. Results: The quiz was begun by 45 neuroradiologists and completed in its entirety by 22. Most respondents were working at urban academic/teaching hospitals(81%) in the USA(42%). The majority (90%) report no clinical neurology rotation during their training. Respondents identified a high proportion (88%) of correct answers in questions about brainstem localizations. Fewer correct answers were selected in questions describing seizure semiology (44%) or flaccid weakness (59%). Conclusions: The small size of our study limits interpretation and generalizability of the findings. Identification of a potential gap in neuroradiology education relating to localization of more complex CNS and PNS presentations merits further exploration.

Background: There are no recommendations regarding endovascular treatment (EVT) for patients with acute ischemic stroke (AIS) due to primary medium vessel occlusion (MeVO). The aim of this study was to examine the willingness to perform EVT among stroke physicians in patients with mild, yet personally-disabling deficits due to MeVO. Methods: In an international survey consisting of 4 cases of primary MeVOs, participants were asked whether the presence of personally-disabling deficits would influence their decision-making for EVT despite the patients having low NIHSS scores. Decision rates were calculated based on physician characteristics. Clustered univariable logistic regression was performed. Results: 366 participants from 44 countries provided 2562 answers. 56.9% opted to perform EVT in scenarios in which the deficit was relevant to the patient’s profession versus 41.0% in which no information regarding patient profession was provided (RR1.39, p<0.001). The largest effect sizes were seen for female participants (RR1.68, 95%CI:1.35-2.09), participants >60 years (RR1.61, 95%CI:1.23-2.10), with more neurointervention experience (RR1.60, 95%CI:1.24-2.06), and who personally performed >100 EVTs per year (RR1.63, 95%CI:1.22-2.17). Conclusions: The presence of a patient-relevant deficit in low NIHSS AIS due to MeVO is an important factor for EVT decision-making. This may have relevance for the conduct and interpretation of low NIHSS EVT randomized trials.

Background: Thrombus embolization during endovascular treatment (EVT) occurs in up to 9% of cases, making secondary medium-vessel occlusions (MeVOs) of particular interest to neurointerventionalists. We sought to gain insight into the current EVT approaches for secondary MeVO stroke in an international case-based survey as there are currently no clear recommendations for EVT in these patients. Methods: Participants were presented with three secondary MeVO cases, each consisting of three case-vignettes with changes in patient neurological status (improvement, no change, unable to assess). Clustered multivariable logistic regression analyses were used to assess factors influencing the decision to treat. Results: 366 physicians from 44 countries took part. The majority (54.1%) were in favor of EVT. Participants were more likely to treat occlusions in the anterior M2/3 (74.3%; risk ratio [RR]2.62, 95%CI:2.27-3.03) or A3 (59.7%; RR2.11, 95%CI:1.83-2.42) segment, compared to the M3/4 segment (28.3%;reference). Physicians were less likely to pursue EVT in patients with neurological improvement (49.9% versus 57.0%; RR0.88, 95%CI:0.83-0.92). Interventionalists and more experienced physicians were more likely to treat secondary MeVOs. Conclusions: Physician’s willingness to treat secondary MeVOs endovascularly is limited and varies per occlusion location and change in neurological status. More evidence on the safety and efficacy of EVT for secondary MeVO stroke is needed.

Background: We evaluated (1) the predictive accuracy and (2) multi-observer reliability of non-contrast CT markers of hematoma expansion (HE). Methods: In 124 patients with spontaneous intracerebral hemorrhage, two investigators documented the presence of six density (Barras density, hypodensity, black hole, swirl, blend, fluid level) and three shape (Barras shape, island, satellite) expansion markers, with discrepancies resolved by a third rater. We defined HE as any one of (1) >6 mL absolute or >33% relative growth of the intraparenchymal hematoma or (2) an absolute growth of >1 mL or new development of intraventricular hematoma. A subsample of 60 patients was used for the inter-observer reliability study in 13 raters. Seven raters participated in the intra-rater study. Results: The sensitivity of markers for HE varied between 4% (fluid level) and 78% (satellite), while specificity ranged from 37% (swirl) to 97% (black hole). Almost perfect inter-rater agreement was observed for the swirl (0.89) and fluid level (0.83) markers, while hypodensity (0.65) showed substantial agreement. Only the blend and fluid level markers achieved substantial intra-rater agreement (> 0.6) in all raters. Conclusions: Non-contrast CT markers of HE showed lower reliability and predictive accuracy than previously reported. Future studies should address means to improve NCCT-based HE prediction.

Background: Ruptured Intracranial Infected Aneurysms (IIAs) are a relatively rare phenomenon, but they portend high mortality. To our knowledge, there are no Canadian studies on IIA with paucity of data on experiences as well. Our purpose is to share experience of a single Canadian tertiary centre in managing ruptured IIA and to conduct a systematic review. Methods: Retrospective case series review of adult patients with ruptured IIA treated at our institution. Secondly, we conducted a systematic review of literature on ruptured IIA between 2011-2021 inclusive. Results: At our institution, with a total 8 cases with ruptured IIA, 4 patients were treated endovascularly and 2 by surgical bypass. For the systematic review, we included 12 non-comparative studies with a total of 547 patients with IIA. Median percentage of ruptured IIA was at least 65.2%, cases that required intervention was 23.7% for surgical cases, and 50% for endovascular cases. The overall median percentage of complications was 5.3%. Conclusions: This study highlights a single Canadian tertiary centre experience in the management of IIA and compares it to the global trends of the last 10 years in a systematic review.

Background: Intracranial hypertension secondary to shunt-failure is a feared complication requiring cross-sectional imaging for diagnosis. We compared dural sinus narrowing and ventriculomegaly as predictors of shunt-failure. Methods: 60 head MRIs and 60 MR venographies of hydrocephalus patients age 0-18 years (n=25) were analyzed. MRI studies were included when f/u clinical data combined with intra-operative findings proved shunt-failure (positive Gold standard) or when MRI was available when the child was well (negative Gold standard). The absence or presence of concerning hydrocephalus was diagnosed. On MRV, the major dural sinuses were independently analyzed with respect to >50% narrowing, suggesting compression by increased CSF pressure. Ventriculomegaly and significant dural sinus narrowing was correlated to the presence/absence of shunt failure as per Gold standard. Results: Sinus narrowing substantially correlated with proven shunt-failure (Cohen’s kappa test 0.635/p<=0.00001 as per Fisher exact test) while ventriculomegaly correlated poorly (0.258/p=0.0751). Sensitivity/specificity was 0.69/0.92 for sinus narrowing and 0.43/0.81 for ventriculomegaly. Conclusions: In this patient cohort, dural sinus narrowing more reliably predicted shunt-failure compared to ventriculomegaly.

Background: Refractory angina is defined as a chronic condition characterized by the presence of angina due to coronary insufficiency which cannot be controlled by a combination of medical therapy, angioplasty and coronary bypass surgery. Prevalence in the United States is estimated to be between 300,000-900,000. Spinal cord stimulation for refractory angina pain relief was first described in 1987 but is still not widely used in North America. We report our experience with this treatment. Methods: A retrospective review of patients referred to the St Pauls Hospital neuromodulation program for consideration of SCS for refractory angina was conducted. Patients underwent implantation using a either a two stage approach (percutaneous or permanent lead trial followed by full system implantation) or full system implantation. Results: Bewtween 2004-2020 36 patients underwent full system implantation (2 patients failed the trial and were not implanted). Of the 36 patients undergoing full system implantation, 33 (92%) experienced significant reduction of angina, increased exercise tolerance and/or medication reduction and were considered successful implantation. Most common lead placement location was at C7 T1. Conclusions: Spinal cord stimulation is an effective therapy for patients suffering from crippling angina pain despite medical optimization.

Background: Neuromodulation unit placement carries a historic infection rate as high as 12%. TYRX antibacterial envelopes (Medtronic Inc., Minneapolis, MN), which are absorbable mesh envelopes that elute minocycline and rifampin, have been used in implantable cardiac devices with substantial risk reduction for infection. Methods: We conducted a retrospective cohort study of consecutive implantable pulse generator (IPG) and intrathecal pump unit implantation with a TYRX antibacterial envelope©. This cohort was then compared to a historical cohort of consecutive patients undergoing IPG or pump placement or revision prior to the use of the envelopes. Results: In the pre-envelope cohort of 151 IPGs in 116 patients, the infection rate was 18/151 (11.9%). In the antibacterial envelope cohort of 233 IPGs in 185 patients, the infection rate was (2.1%). The absolute risk reduction was 4.6% (95% CI, 0.045-0.048), The pre-envelope cohort of 41 pumps in 39 patients, the infection rate was 6/41 (14.6%). In the antibacterial envelope cohort of 59 pumps in 54 patients, the infection rate was (1.7%). The absolute risk reduction was 12.9% (95% CI 1.6-24.3). Conclusions: Usage of an antibacterial envelope for neuromodulation has resulted in a lower infection rate at our center. Based on these results, we recommend the use of antimicrobial envelopes.

Background: The success of repeat surgery for recurrent trigeminal neuralgia (TN)—with microvascular decompression (MVD), percutaneous rhizotomy (PR), or stereotactic radiosurgery (SRS)—is not well-studied. We performed a systematic review and meta-analysis of the literature on repeat surgery recurrent TN, focusing on the durability of pain relief and relative efficacy of MVD, PR, and SRS. Methods: A PRISMA systematic review of Medline/Embase/Pubmed identified studies of adults with unilateral idiopathic TN undergoing repeat surgery. The primary outcome of complete pain relief (CPR) at last follow-up was analyzed with a multivariate mixed-effects meta-analysis of proportions. Results: Seventy-eight studies met criteria; 61 were included in meta-analyses, containing 29/14/25 cohorts with 900/684/1353 patients undergoing MVD/PR/SRS respectively (mean age 64.7 years, 41% males). Initial CPR was 69% (74%/85%/52%). CPR at mean 39.7 month follow-up (38.3/38.8/41.0) was 48% (59%/60%/34%). Initial CPR for both MVD (CPR: 0.78 [0.70-0.85]) and PR (CPR: 0.93 [0.83-0.98]) was superior to SRS (CPR: 0.48 [0.35-0.61]). At follow-up, MVD (0.45 [0.32-0.58]) and PR (0.45 [0.30-0.60]) trended towards superior CPR versus SRS (0.25 [0.15-0.37]). Conclusions: Half of recurrent TN patients achieve good pain control 3 years after repeat surgery. MVD/PR showed superior initial pain relief and likely better long-term relief. These findings can inform surgical decision-making in this challenging population.

Background: The dorsal root ganglion (DRG) has been established as an important structure in the development and modulation of chonic neuropathic pain and has demonstrated superiority over spinal cord stimulation in the management of challenging neuropathic pain conditions, including complex regional pain syndrome and chronic post-spine surgery neuropathic pain. DRG has only been available in Canada for patient application since January 2020. The St Pauls Hospital Neuromodulation Program was one of the first Canadian centers to offer this procedure. Methods: We reviewed our early experience with DRG therapy in 10 patients. Patient-reported outcome measures were collected pre-trial, post-trial, and post-device implantation, to determine the efficacy of DRG. We hypothesized that DRG stimulation would demonstrate a meaningful change in PROMIS-29 domains and at least 50% improvement in pain intensity at 8 wks. Results: All patients demonstrated a > 5 point change in T scores in PROMIS-29 domains suggesting a meaningful benefit. Patients also demonstrated a percentage pain improvement at 8 wks of 64 % based on a numerical rating scale. No major complications were observed. Conclusions: DRG stimulation is a safe and effective treatment option for neuropathic pain.

Background: The challenges of chronic pain management, and resulting poorer outcomes, in workers’ compensation (WCB) patients has been well established. Spinal cord stimulation (SCS) has been used for the management of low back and radicular neuropathic pain with varying effectiveness and it’s efficacy in the WCB population has been challenged. We sought to examine our experience using SCS in WCB compared to non WCB patients. Methods: A retrospective analysis of 71 WCB patients assessed and treated at the St Pauls Hospital neuromodulation program between 2016-2021 was performed. This group was compared to a cohort on non WCB patients in terms of the likelhood of being offered a trial, proceeding with trial if offered, and the likelhood of a successful trial proceeding to implant. Results: Compared to non WCB, the WCB patients were more likely to be offered a trial (86% vs 77%) and more likely to proceed with a trial if offered (82% vs 71%). Trial to implant ratios were similar in both WCB and non WCB patients (78% vs 77%). Conclusions: WCB patients were more likely to be offered a SCS trial and more likely to accept if offered, compared to non-WCB patients. However, both groups were similar in trial to implant probability.

Background: Until recently, no effective treatment was available for spinal muscular atrophy (SMA). In 2017, Health Canada approved intrathecal Nusinersen a medication that prevents degeneration of the motor neurons in the spinal cord. The administration is intrathecally most commonly via lumbar puncture (LP) to have a direct effect on the motor neurons of the spinal cord. Many older patients with SMA and concomitant spinal deformities present technical challenges to access the thecal sac. Different routes have been described for delivery of the medication whoever these techniques may require sedation, are associated with radiation exposure, and demand experience personnel. Methods: A new surgical technique has been proposed to overcome these obstacles by combining two Health Canada approved devices: 1) an intrathecal catheter designed for intrathecal baclofen pumps and 2) an implantable subcutaneous port designed for intravascular medication administration Results: We describe the technical nuances and outline the clinical outcomes of six patients with complex spine deformities who have undergone such an implant for administration of Nusinersen. Conclusions: We discuss the benefits of the procedure which includes: 1) administration in the outpatient setting without sedation, 2) avoidance of costly imaging and experienced personnel, and 3) placement of the catheter in the cervicothoracic junction.

Background: All guidelines for DBS in Parkinson’s disease (PD) include a contraindication for ‘dementia’. It is unclear where this cut-off should occur and if patients with mild cognitive impairment (MCI) do not do as well. This prospective cohort analysis assessed if pre-operative cognition affected post-operative quality of life. Methods: PD patients receiving bilateral STN-DBS (n=100) were prospectively studied using STROBE guidelines. All had Montreal Cognitive Assessment (MoCA), motor (UPDRS), mood (BDI-II), and quality of life (Parkinson Disease Questionnaire summary index, PDQ-39-SI). Two cohorts, pre-operative MCI (MoCA:18-25) and normal cognition (MoCA:26-30), had post-operative PDQ-39-SI at 1-year. The primary outcome was the proportion of patients with an improved PDQ-39-SI at 1-year. Results: Cohorts were not significantly different in age, severity of illness, response to dopamine, or mood. MCI was present in 27/100. Improved quality of life at 1-year occurred in 75% with normal cognition and 70% with MCI (p=0.54) with RR=1.1 (95% CI, 0.8-1.5). Linear regression analysis showed no correlation between pre-operative cognition and post-operative outcome (R2=0.02). Conclusions: Parkinson’s patients with MCI should be offered DBS if their motor symptoms require surgery. Guidelines for DBS surgery in PD should change from “dementia is contraindicated” to “patients require adequate cognitive functioning, MoCA318”.

Background: One of the rare but urgent presentations of a pituitary tumor is pituitary apoplexy. In this case series, we describe our experience regarding the cranial nerve recovery in patients with pituitary apoplexy following endoscopic endonasal transsphenoidal surgery (EETS). Methods: Retrospective cohort study with patient characteristics, tumor type, endocrine data, operation data collected. Postoperative data were extracted for the follow-up period available for each patient. Results: 15 pituitary apoplexy cases were identified. The cranial nerve deficits presented at admission were: visual deficit (33% patients); unilateral third nerve palsy (47% patients), unilateral sixth nerve palsy (27% patients). Postoperatively, 60% of patients with preoperative visual deficit had normal visual fields and the other 40% showed improvement. From those with oculomotor nerve dysfunction preoperatively, 43% have returned to normal nerve function and 57% presented improvement. 75% cases of abducens nerve palsy resolved postoperatively, while 25% showed improvement. Conclusions: Based on this series, surgical treatment should be offered to patients presenting with cranial nerve deficit in the setting of pituitary apoplexy. In this series, all cranial nerve deficits either returned to normal or improved following surgery. Though a small series, the presented results are superior to those reported in the literature for conservative management.

Background: Historically, frame-based stereotactic brain biopsy (SBB) has played an important role in the diagnosis of intracranial lesions. We performed a single centre analysis of the outcomes and efficacy of SBB at the London Health Sciences Centre (LHSC). Methods: We performed a retrospective chart review of frame-based SBB from 2006 to 2017 at the LHSC. Intra-operative and final pathology reports were analyzed for biopsy diagnosis and the diagnosis was compared with pre-operative neuroimaging reports for correlation. SBB-associated morbidity and mortality were investigated using chart review and post-operative neuroimaging. Results: 173 consecutive patients were identified. The overall morbidity rate was 8.7% (15 cases) and mortality rate was 0.6% (1 case). Final biopsy diagnostic accuracy was 96%, intra-operative diagnostic accuracy was 94% and pre-operative imaging diagnostic accuracy was 65%. Elevated partial thromboplastin time and the presence of hemorrhage on post-operative CT were associated with neurological morbidity and mortality. The need to obtain three or greater samples the time of biopsy was associated with non-diagnostic biopsy. Conclusions: At the LHSC, SBB is a relatively safe and effective surgical procedure with high diagnostic yield and relatively low risk of complications. Intra-operative pathology has a high efficacy in determining diagnosis when compared to final pathology.