Background: Burgeoning EEG demand has largely gone unmet with insufficient supply of manpower and equipment. Quantitative EEG (QEEG) may help compress large volumes of data for expedited review. We sought to determine the current use of QEEG in Canada through a national EEG technologist survey. Methods: A 10-item questionnaire was administered to participants at the 2016 meeting of the Canadian Association of Electroneurophysiology Technologists, which occurred in parallel with the Canadian Neurological Sciences Federation meeting. Results: A response rate of 63% (14/22) represented 12 institutions (11 adult, 6 paediatric) over six provinces with 73% of the national population. Only academic institutions (9/12) used QEEG, representing five provinces with 70% of the national population. Most institutions generated QEEG either real-time or retrospectively in the critical care and epilepsy monitoring units for long-term monitoring and automated seizure detection. The most used trends were spectrographic, seizure detection, and artifact detection. Montage use, QEEG duration, and timebase settings were highly variable. Conclusions: QEEG is in surprisingly frequent use across Canada. There is no consensus on optimal QEEG use, which mirrors uncertainty in the literature. The relative ubiquity of QEEG in Canada offers promise for collaborative multicentre research into unlocking the full potential of QEEG in enhancing patient care.

Background: Intermittent EEG attenuations have relatively clear significance in pediatric populations, but a consistent clinical correlation has not been identified in adults. While generally seen in metabolic encephalopathies, the specific clinical correlates and prognostic value have not been determined. Methods: We prospectively collected 22 consecutive EEGs noted to have intermittent generalized attenuations. Baseline and discharge modified Rankin Scale (mRS), diagnosis at discharge, EEG altering medications, ICU admissions, relevant imaging, mental status, the location the patient was discharged to, and pertinent lab values were assessed. Results: Mean patient age was 73.7 (SD=11.0) at admission. Twelve of the twenty-two patients (55%) died during their course in hospital. Four patients (18.2%) did not have a change in mRS score from baseline to discharge, while most had an increase in their mRS scores reflecting increased disability. Twelve patients (55%) were admitted to the ICU or CCU during their time in hospital. The most common etiologies were metabolic encephalopathies, and often associated with triphasic waves. Conclusions: Intermittent generalized EEG attenuations in adults are associated with severe metabolic encephalopathies and poor outcome including high association with mortality. The physiologic mechanism of generalized attenuations in poorly understood. Patients with this pattern should be suspected of having a severe metabolic encephalopathy and treated accordingly.

Background: Diaphragm pacing (DP) is an experimental ALS treatment, available through a compassionate use program. Eligibility requires forced vital capacity (FVC) between 45-50% predicted and phrenic nerve conduction study (NCS) evidence showing the diaphragm can be electrically stimulated. Diaphragm ultrasound (DU) also evaluates diaphragm function by demonstrating thickening with inspiration. Methods: A 63 year old man with advanced ALS requested DP as his respiratory functions worsened. He was wheelchair bound and had severe dysarthria and dysphagia. He had exertional dyspnea and used CPAP at night for obstructive apnea. Results: FVC was 47% predicted. Initial phrenic NCS showed a normal response on the right but no response on the left, making him ineligible for DP. Diaphragm function was further assessed with DU. This showed normal thickening with inspiration bilaterally. The DU result prompted repeating the right phrenic NCS which then showed a normal response. He successfully completed surgical implantation of diaphragm leads for DP. At surgery both diaphragms showed good responses to electrical stimulation. Conclusions: Phrenic NCS can be technically challenging and yield a false positive (absent) result. In this patient, DU indicated good diaphragm function, which prompted repeating phrenic NCS. The normal phrenic NCS allowed the patient to pursue DP.

Background: Metallic susceptibility artifact (MSA) on brain MRI has been described rarely in adult population as an incidental finding in patients undergone cardiac surgery, catheterization or prosthetic heart valve, but has not been described before in the pediatric population. Here we present two pediatric cases with MSA on brain MRI post-cardiac surgery. Case Series:Patient1: 13-month-old girl with Transposition of great arteries, aortic coarctation and multiple VSDs, who twice had open heart surgery requiring cardiac bypass. She presented with bilateral lower extremity paralysis secondary to spinal cord embolic infarction, Brain MRI showed an incidental finding of hundreds of diffuse foci of brain MSA. Patient2: 5-year-old boy with Trisomy21, Atrial-ventricular septal defect repaired at age one year. His brain MRI showed incidental finding of multiple, widespread foci of MSA during investigation for gait disturbance. Discussion: Here we present two pediatric patients post-cardiac surgery, found to have multiple scattered MSA in cerebral and cerebellar hemispheres and brain stem. Presumably, these are secondary to metallic microthrombi during cardiac surgery, however, neither had prosthetic material. Metallic microthrombi may be related to cardio-pulmonary bypass. Pediatric cardiac surgery patients should be studied, to understand the significance of these lesions and further distinguish the cause and association of these findings.

Background: Although surgery is the gold standard for treating brain arteriovenous malformations (AVMs), surgical techniques may not be suitable if the AVM is located in eloquent regions of the brain, such as the motor cortex. An alternative method for these cases is stereotactic radiosurgery. Localization of the motor cortex using functional magnetic resonance imaging (fMRI) is useful for helping the neurosurgeon determine which type of surgery is appropriate. We report a patient with a left frontal AVM near the motor cortex. fMRI was requested to localize motor functioning. Methods: The tasks included bilateral finger tapping, arm rubbing against the scanner, and abdominal tightening. All fMRI analyses were performed using BrainVoyager. Results: The fMRI results revealed that finger tapping and arm rubbing activated the precentral gyrus and supplementary motor area, and abdominal tightening activated the paracentral gyrus. These regions of activation were shown to be just posterior to the AVM and were mapped using neuronavigation during surgery. Conclusions: Given that the fMRI activation in the motor cortex was posterior to the AVM, the neurosurgeon felt confident that surgery could be performed. These findings elucidate the utility of fMRI for pre-surgical localization and for determining whether surgery or radiosurgery is appropriate in cases in which the AVM is near eloquent cortex.

Background: Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are noninvasive and reliable tools for mapping eloquent cortex and white matter tracks prior to brain surgery. In this case, fMRI and DTI were used to inform the surgical approach in the resection of a deep cavernous malformation near the right lentiform nucleus. Post-surgery, the patient developed a fluid collection in the frontal cortex that applied pressure to M1, which led to reorganization of the motor cortex. Methods: The tasks included finger tapping, arm rubbing, and lip licking. All fMRI analyses were performed using BrainVoyager. Tensors were tracked from 20-direction diffusion MR images using DSIStudio. Results: An fMRI scan one-month pre-surgery revealed activation in M1 for the three tasks. A six-month follow-up scan revealed motor activation had been displaced by the fluid collection. A ten-month follow-up scan revealed that activation had shifted from its original location to more lateral and anterior regions. DTI revealed atrophy in the tracts through the insula, but increase in tracts through the lentiform nucleus. Conclusions: The results provide evidence that components of motor processing subserved by M1 can be taken over by adjacent regions, and that the rapid onset of pressure can lead to reorganization in a relatively short time period.

Background: Cerebral arteriovenous malformations (AVMs) are a type of vascular abnormality characterized by abnormal connections between arteries and veins without the normal interposed capillary bed. The gold standard for diagnosis is digital subtraction angiography (DSA). Functional MRI (fMRI), particularly with the increased sensitivity at ultra-high field (>=7T), may help to further characterize AVMs, but has not been performed in this population. Methods: We present a functional and structural neuroimaging analysis of an AVM at 7T. Resting-state fMRI was analyzed using independent components analysis (ICA) and compared to normal controls. Structural T1-weighted images were obtained at 1.5T and 7T. The patient also underwent DSA. Results: A 44 year-old, right handed man presented with a generalized tonic-clonic seizure. MRI at 1.5T and 7T revealed an AVM located in the pineal region measuring 3.2 cm. Multiple large feeder vessels were identified, and the AVM drained into the vein of Galen, clearly visualized on the 7T images. Functional imaging revealed an altered default mode network and ICA-identified vascular networks corresponding to the AVM. Conclusions: Imaging at 7T clearly delineates AVM structure. Functional connectivity is altered by the AVM. Vessel-specific independent components were identified that may be helpful for AVM characterization.

Background: Studies have placed the rate of infection associated with neuromodulation units to be up to 20%. We present our experience with the TYRX absorbable antibiotic envelope. Our length of follow-up adds to the body of evidence around the use of antibiotic envelops. Methods: We conducted a retrospective chart review of patients referred to our center for either new implantation or revision of neuromodulation units between July 2014 and September 2016. Consecutive cases were included for analysis. We included a control group of consecutive patients with neuromodulation units placed immediately prior to our experience with the TYRX envelopes for comparison Results: Between July 2014 and September 2016, 76 patients had 81 instances of neuromodulation unit insertion. All patients received the TYRX antibiotic envelope. There were no incidences of infection involving antibiotic envelope-containing implants over an average follow-up period of 11 months. In 77 consecutive cases of neuromodulation unit implantation prior to usage of the antibiotic pouch, there were 4 instances of infection (5.2%). Conclusions: Our single center experience demonstrates a significant drop in the rate of infections with the use of an antibiotic envelope for neuromodulation unit implantation. We consider the routine use of the envelope to be a cost-effective method of infection avoidance.

Background: The expansion of neuromodulation intervention for complex pain syndromes has been signifcant in the last few decades. Considering the increased load of patients, we thought about evaluating the level of awareness among different medical experts to help assessing their familiarity with spinal cord stimulator (SCS). Methods: Survey has been sent to general practitioners, family physicians, pain specialists and spine surgeons. The main outlets of the survey aims to assess the followings:

The main source of their knowledge about SC

Familiarity with candidates who may benefit from SC

Introducing the concept of SC to their patients as an adjunctive treatment

Frequency of patients’ referral for SC

Main reason for referring their patients

Familiarity with centres providing SCS

Results: EResults will be provided upon analysing the data from the collected surveys. Conclusions: The expansion in neurmodulation is expected to help patients with intractable pain syndromes. Hence, the survey would potentially help to explore the deficiencies in health workers awareness about SCS and outline future directions toward proper patients counseling and optimising their referral to neuromodulation centres.

Background: Cubital tunnel syndrome is the second most frequent upper extremity entrapment neuropathy. Various surgical approaches have been described in the literature for Ulnar nerve decompression, ranging from open In-situ decompression to endoscopic Ulnar nerve release. In this technical note we describe a new endoscopic approach for Ulnar nerve decompression. Methods: Four cadavers, a total of eight fresh arms were dissected using our new endoscopic technique. The technique involves a 2.5cm skin incision placed 2.5cm distal to the medial epicondyle, and perpendicular to the long nerve axis. Early identification of motor branches was achieved using this skin incision. Under endoscopic view using 30 degree rigid scope Ulnar nerves were decompressed Results: Early identification of motor branches was achieved using distally placed skin incision in all eight arms. Conclusions: The safety of identifying Ulnar nerve motor branches in the early steps of the procedure, and the avoidance of scar formation over the elbow joint are the proposed advantages of this approach. More clinical studies needed to validate this outcome.

Background: Hyponatremia has been found to be associated with increased complications in a variety of surgical populations. No study looked specifically at patients undergoing spine surgery. We also specifically address whether it has an effect on the typical low-risk patient admitted for degenerative spine disease, a population that forms the major bulk of clinical practice. Methods: Data was obtained from the American college of surgeons National Surgical Quality Improvement Program (ACS-NSQIP). All patients who underwent elective spinal surgery for degenerative disease from 2011 to 2013 were included. The two arms (normonatremic and hyponatremic) were then compared. Results: A total of 58049 patients were included, 3037 were hyponatremic. Hyponatremic patients were older and had more comorbidities. They also developed more minor and major complications. When all comorbidities were controlled for, hyponatremia was only associated with increased minor but not major complications. These patients were more likely to require a blood transfusion (OR=1.23, CI 1.10-1.43) and a prolonged hospital stay (OR=1.52, CI 1.33-1.75). Conclusions: This study finds an association between hyponatremia and postoperative adverse events in a low risk population that forms the major bulk of clinical practice. This addresses a potential target for quality improvement strategies with significant cost saving implications.

Background: Spinal computer-assisted navigation (CAN) is proven to increase instrumentation accuracy. Adoption remains limited by workflow restrictions, learning curves and costs. Here, we assess spinal CAN usage among Ontario surgeons to identify gaps in application, and temporal trends of usage. Methods: A prospectively-collected database of provincial insurance billables and diagnostic codes was reviewed retrospectively, from 2002-2014. Patients undergoing instrumented spinal fusions or percutaneous vertebroplasty/kyphoplasty were identified. Fee and diagnostic codes were applied to distinguish surgical indication and approach. The use of intra-operative navigation was determined for each case. Results: We identified 4607 instrumented spinal fusions in our cohort. Most cases were performed by orthopedic surgeons (63.2%) and the remainder by neurosurgeons. Of 2239 cases with identifiable etiology, CAN was utilized in 8.8%, predominantly for trauma and degenerative pathologies rather than deformity. In univariate analyses, CAN was used more often by neurosurgeons (21.0% vs. 12.4%, p<0.001), in academic institutions (15.9% vs. 12.3%, p<0.001), and when performed in/after 2010 (18.9% vs. 8.9%, p<0.001). Differences by specialty and year remained significant in multiple logistic regression. Conclusions: Spinal CAN has proven benefit for instrumentation accuracy, but is used preferentially by academic neurosurgeons. Significant gains must be made in cost and usability to improve access across disciplines and institutions.

Background: Morbidity can be high in the management of adult spinal deformity patients. Complications include blood loss (EBL), durotomy, radicular pain, and postoperative hardware failure. Utilization of one versus two spinal surgeons in spinal deformity correction reduces overall perioperative morbidity is unclear. Methods: All procedures were performed by surgeons at a single institution between January 2012-2015. Patients were followed for a minimum of one year and maximum of four years. We retrospectively reviewed 60 cases of adult spinal deformity. Our cohort was divided into 1 versus 2 surgeons (12 vs 48 cases). We analyzed these cases for estimated blood loss and peri-operative complications. Results: Cases involving long thoracic to pelvis correction (T3-T6) was 20.8% in the 2 surgeons group and 8.3% in the 1 surgeon group. The EBL >3.0 L for 1 versus 2 surgeon groups were 25% and 41.6% respectively. Major complications in the 1 versus 2 surgeon group were 25% and 47.9% and the revision rates were 25% versus 37.5%. The percentage of minor complications in the 1 versus 2 surgeon group was 33.3% versus 14.6%. Conclusions: Utilizing two surgeons did not reduce complication rates. Procedures performed by two surgeons were more extensive deformity corrections. The extent of correction is the likely explanation for differing complication rates.

Background: Instrumentation failure (IF) such proximal junctional kyphosis/failure or distal junctional failure (PJK/PJF/DJF), rod fracture and screw-loosening can cause morbidity in patients with spinal deformity correction. Factors such as bone mineral density (BMD) or region of deformity correction may play a role in postoperative IF. Methods: We reviewed the relationship between IF and BMD or extent of spinal deformity. IF includes PJK/PJF/DJF, fractured rod, screw-looseing, radiculopathy, and non-union. BMD groups included Normal, osteopenia/osteoporosis, and Unknown. The extent of correction included Lumbar, Short Thoracolumbar (5-8 levels), Long Thoracolumbar (8 to 12 levels), and Cervical-thoracic. Results: 60 patients (41:19 F:M) were included, with average age of 65. Total IF=29 patients (48.3%). Normal BMD in N=14, with half of them (50.0%) developing IF; Low BMD in N=15, with one-third of them (33.3%) developing IF. Lumbar correction was performed in N=19, with IF in 36.8%; Short Thoracolumbar correction was performed in N=28, with IF in 46.4%; Long Thoracolumbar correction was performed in N=11, with IF in 81.8%; and Cervical correction in N=2, with no postoperative IF. Conclusions: Patients that received long-segment thoracolumbar had the highest rates of postoperative morbidity. We did not demonstrate an association between abnormal BMD and postoperative IF. A larger study would be needed for further investigations.

Background: Optimal surgical management for flexion--distraction cervical spine injuries remains controversial with anterior, posterior, and circumferential fixation being accepted. Here, we examined risk factors for clinical and radiographic failure in patients with one segment cervical flexion-distraction injuries having undergone anterior surgical fixation. Methods: A retrospective review of 57 consecutive patients undergoing anterior fixation for cervical flexion-distraction injuries between 2008-2012 was performed. The primary outcome was the number of patients requiring additional surgical stabilization and/or radiographic failure. Data collected inlcuded age, gender, mechanism and level of injury, facet pattern injury, and vertebral endplate fracture. Results: Six patients failed clinically and/or radiographically (11%). Four patients (7%) required additional posterior fixation. Two patients identified met radiographic failure criteria, however had fused radiographically, were stable clinically, and no further treatment was pursued. Progressive kyphosis and translation correlated with need for revision (p<0.05 and p=0.02, respectively). No differences were identified for all other clinical and radiological factors assessed. Conclusions: This study supports the growing body of evidence for anterior fixation alone for flexion-distraction injuries. Findings suggest that measurements including segmental translation and kyphosis may predict radiographic failure and need for further surgical stabilization in some patients. Assessment for independent risk factors for anterior approach failure with a validated predictive scoring model should be considered.

Background: Hirayama disease (HD) is characterized by progressive cervical myelopathy caused by repetive neck flexion leading to forward displacement of the posterior dural sack with compression and injury of the spinal cord. Typically, the C7-T1 myotomes become weak and atrophic, while sparing sensation. Here we present two Canadian cases of this rare entity. Methods: Two cases of HD are presented and literature reviewed, showing the diagnostic and therapeutic challenges of this disease. Results: Case 1 is a 17-year-old male professional singer and musician. He presented with bilateral progressive hand weakness, which was aggrevated while playing the violine. Cervical MRI showed increased T2-weighted signaling at C5-7, but a correct diagnosis could not be identified. Eventually, dynamic cervical MRI showed the compression and he underwent an anterior cervical discectomy and fusion (ACDF) at C5-C6 and C6-C7 without complications. Case 2 is a 19-year-old female with progressive right hand weakness. After numerous investigations, a dynamic cervical MRI diagnosed her with HD with classic findings and she underwent an ACDF at C6-C7 without complications. Conclusions: Hiryama’s disease is rare, but should be kept in mind when cervical cord signal changes cannot be explained by standard MRI. Dynamic MRI is imperative to correct diagnosis and anterior fusion shows good outcomes in its management.

Background: Surgery to remove dumbbell nerve sheath tumors (NST) is complex, and is accompanied by significant operative and perioperative challenges. Historically, resection of dumbbell NST required large operations involving opening the chest and laminectomy, often accompanied by instrumentation. We describe a case series of 5 patients who underwent single stage thorascopic-guided resection of dumbbell schwannoma at our institution. Methods: 5 cases presented consisted of moderate to large NST, which contained intraforaminal components. Tumor location ranged from T3-T9, with most tumors spanning 2-3 vertebral bodies. Presentation ranged from discomfort/pain (most common) to one presentation of neurologic deficit with difficulty with ambulation. Results: Thorascopic assisted resection accomplished gross total resection in 4 of the 5 cases. In all cases there was no significant neurologic deficit, although one patient reported transient numbness following the operation and all patients made significant improvement post operatively. The length of stay for these cases ranged from 1-6 days. Conclusions: Thorascopic assisted resection of dumbbell NST can be performed safely and with good outcomes by using the corridor the tumor produces. This approach reduces the need for instrumentation, length of stay and post operative complication rates relative to traditional approaches. To perform this approach effectively, good co-operation between the neurosurgeon and thoracic surgeon needs to be present.

Background: Iatrogenic dural tear a complication of spinal surgery with significant morbidity and cost to the healthcare system. The optimal management is unclear, and therefore we aimed to survey current practices among Canadian practitioners. Methods: A questionnaire was administered to members of the Canadian Neurological Surgeon’s Society designed to explore methods of closure of iatrogenic durotomy. Results: Spinal surgeons were surveyed with a 55% response rate (n=91). For pinhole sized tears there is a trend toward sealant fixation(36.7%). Medium and large sized tears are predominantly closed with sutures and sealant(67% and 80%, respectively). Anterior tears are managed using sealant alone(48%). Posterior tears are treated with a combination of sutures and sealant(73.8%). Nerve root tears are treated with either sealant alone(50%). Most respondents recommended bed rest for at least 24 hours in the setting of medium(73.2%) and large(89.1%) dural tears. Conclusions: This study elucidates the areas of uncertainty with regard to iatrogenic dural tear management. There is disagreement regarding management of anterior and nerve root tears, pin-hole sized tears in any location of the spine, and whether patients should be admitted to hospital or on bed-rest following a pin-hole sized dural tear. There is a need for a robust comparative research study of dural repair strategies.

Background: Two broad categories for the surgical management of symptomatic spondylolysis exist: decompression, or direct reduction and fixation. Direct fixation can maintain mobility and leads to improved outcomes over spinal fusion. The ‘smiley face’ technique is a direct fixation method of pars defect repair that uses one bent rod to reduce the number of linkage points and simplify the construct. Methods: Bilateral pars defects at L3 and L5 were repaired using the ‘smiley face’ technique. Patient reported outcomes, including the Oswestry Disability Index (ODI) and visual analog scale (VAS) scores for back and leg pain were assessed preoperatively and again at 6 weeks postoperatively. Results: The patient underwent a soft tissue preserving multi-level bilateral L3 and L5 pars defect repair using the smiley face technique while utilizing radiation-free 3D optical imaging to capture multiple points for registration despite minimal laminar exposure. The patient’s ODI and lower back VAS scores decreased from 25 to 8 and 7.5 to 4 respectively, after surgery, correlating to an excellent outcome on ODI. Conclusions: The smiley face technique can be used with soft tissue preserving techniques to achieve adequate bony reduction while maintaining intersegmental mobility in patients with multi-level pars defects. 3D imaging allows soft tissue preservation with increased registration points for intraoperative navigation.

Background: Current lumbar intervertebral disc prostheses provide suboptimal symptom relief with little natural load-cushioning. PVA-C is a promising biocompatible material, and our previous study finds that it can closely mimic the properties of nucleus pulposus. However, pure PVA-C does not possess adequate stiffness to mimic the annulus fibrosus. Methods: Composite particle-reinforced PVA-C formulations were tested to identify methods that could increase the elastic modulus. This included: sephadex, hydroxyapatite (stock) and hydroxyapatite (in-solution synthesis). All formulations were tested using 15% PVA-C and 5% reinforcing agent. Indentation and durometer tests were performed as well as simple compression, compressive stress relaxation and creep. Results: Indentation and durometer results did not clearly reveal any specific formulations that significantly improved stiffness. The addition of in-solution synthesized hydroxyapatite resulted in 1.15 to 2 time increase in elastic modulus (0.3-0.9 MPa) and associated decrease in stress relaxation and creep. The addition of stock hydroxyapatite and spehadex (G100f and G50sf) lowered the elastic modulus and increased stress relaxation and creep. Conclusions: In-solution synthesized hydroxyapatite is the only particle-reinforced composite PVA-C formulation that exhibited greater stiffness than pure PVA-C. The elastic modulus will need to be increased by 5-10x to adequately mimic the annulus fibrosus. A fiber-reinforced composite will likely be needed to accomplish this.