James M Drake

University of Toronto, Toronto, Ontario, Canada

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Publications (268)569.61 Total impact

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    ABSTRACT: This study aims to develop and establish the content validity of multiple expert rating instruments to assess performance in endoscopic third ventriculostomy (ETV), collectively called the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT). The important aspects of ETV were identified through a review of current literature, ETV videos, and discussion with neurosurgeons, fellows, and residents. Three assessment measures were subsequently developed: a procedure-specific checklist (CL), a CL of surgical errors, and a global rating scale (GRS). Neurosurgeons from various countries, all identified as experts in ETV, were then invited to participate in a modified Delphi survey to establish the content validity of these instruments. In each Delphi round, experts rated their agreement including each procedural step, error, and GRS item in the respective instruments on a 5-point Likert scale. Seventeen experts agreed to participate in the study and completed all Delphi rounds. After item generation, a total of 27 procedural CL items, 26 error CL items, and 9 GRS items were posed to Delphi panelists for rating. An additional 17 procedural CL items, 12 error CL items, and 1 GRS item were added by panelists. After three rounds, strong consensus (>80 % agreement) was achieved on 35 procedural CL items, 29 error CL items, and 10 GRS items. Moderate consensus (50-80 % agreement) was achieved on an additional 7 procedural CL items and 1 error CL item. The final procedural and error checklist contained 42 and 30 items, respectively (divided into setup, exposure, navigation, ventriculostomy, and closure). The final GRS contained 10 items. We have established the content validity of three ETV assessment measures by iterative consensus of an international expert panel. Each measure provides unique assessment information and thus can be used individually or in combination, depending on the characteristics of the learner and the purpose of the assessment. These instruments must now be evaluated in both the simulated and operative settings, to determine their construct validity and reliability. Ultimately, the measures contained in the NEVAT may prove suitable for formative assessment during ETV training and potentially as summative assessment measures during certification.
    Child s Nervous System 05/2015; DOI:10.1007/s00381-015-2716-4 · 1.16 Impact Factor
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    ABSTRACT: As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p < 0.001; SRME 7.75 vs. 2.80, p < 0.001). Similarly, secondary task performance deteriorated from baseline to dual-task among novices (RRT 0.63 vs. 1.76 s, p < 0.006 and SDR 1.00 vs. 0.27, p < 0.001), but not experts (RRT 0.63 vs. 0.73 s, p = 0.124 and SDR 1.00 vs. 0.97, p = 0.178). In phase 2, novices practiced surgical knot-tying on the bench top simulator during consecutive dual-task trials. A significant increase in SDR (F(9,63) = 6.63, p < 0.001, f = 0.97) and decrease in SRME (F(9,63) = 9.39, p < 0.001, f = 1.04) was observed during simulation training, while RRT did not change significantly (F(9,63) = 1.18, p < 0.32, f = 0.41). The results suggest subjective ratings and dual-task performance can be used to track changes in CL among novices, particularly in early phases of simulation-based skills training. The implications for measuring CL in simulation instructional design research are discussed.
    Advances in Health Sciences Education 03/2015; DOI:10.1007/s10459-015-9599-8 · 2.71 Impact Factor
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    ABSTRACT: We analyzed the spatial distribution and concordance of fast (>10Hz) and slow (<5Hz) electroencephalogram (EEG) components of ictal activities and interictal epileptiform discharges (IIED) recorded by intracranial video EEG (IVEEG) in children with epileptic spasms (ES). We studied eight children with ES, who underwent IVEEG before resective surgery for epilepsy. We quantified the root-mean-square (RMS) amplitude of the fast and slow components of ictal activities during ES and IIED. We compared the concordance between the spatial distributions of the fast and slow components of ES and IIED. There was a larger concordance between the spatial distributions of the fast and slow components in IIED than in ES (p=0.0206 and 0.0401). The spatial concordance between the fast and slow EEG components was significantly different between ES and IIED. The mechanisms underlying the generation of slow EEG components may differ between ES and IIED. The slow EEG components of ES might indicate an extensive epileptic network involving remote symptomatic zones for ES in either the cortical or subcortical areas. The high spatial concordance between the fast and slow components of IIED suggests the involvement of a local inhibitory process within the epileptic cortex. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
    Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 12/2014; DOI:10.1016/j.clinph.2014.12.005 · 2.98 Impact Factor
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    ABSTRACT: OBJECT Endoscopic third ventriculostomy (ETV) is an effective but technically demanding procedure with significant risk. Current simulators, including human cadavers, animal models, and virtual reality systems, are expensive, relatively inaccessible, and can lack realistic sensory feedback. The purpose of this study was to construct a realistic, low-cost, reusable brain simulator for ETV and evaluate its fidelity. METHODS A brain silicone replica mimicking normal mechanical properties of a 4-month-old child with hydrocephalus was constructed, encased in the replicated skull, and immersed in water. Realistic intraventricular landmarks included the choroid plexus, veins, mammillary bodies, infundibular recess, and basilar artery. The thinned-out third ventricle floor, which dissects appropriately, is quickly replaceable. Standard neuroendoscopic equipment including irrigation is used. Bleeding scenarios are also incorporated. A total of 16 neurosurgical trainees (Postgraduate Years 1-6) and 9 pediatric and adult neurosurgeons tested the simulator. All participants filled out questionnaires (5-point Likert-type items) to rate the simulator for face and content validity. RESULTS The simulator is portable, robust, and sets up in minutes. More than 95% of participants agreed or strongly agreed that the simulator's anatomical features, tissue properties, and bleeding scenarios were a realistic representation of that seen during an ETV. Participants stated that the simulator helped develop the required hand-eye coordination and camera skills, and the training exercise was valuable. CONCLUSIONS A low-cost, reusable, silicone-based ETV simulator realistically represents the surgical procedure to trainees and neurosurgeons. It can help them develop the technical and cognitive skills for ETV including dealing with complications.
    Journal of Neurosurgery Pediatrics 10/2014; 15(1):1-7. DOI:10.3171/2014.9.PEDS1447 · 1.37 Impact Factor
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    ABSTRACT: The indications for operating on lesions in or near areas of cortical eloquence balance the benefit of resection with the risk of permanent neurological deficit. In adults, awake craniotomy has become a versatile tool in tumor, epilepsy and functional neurosurgery, permitting intra-operative stimulation mapping particularly for language, sensory and motor cortical pathways. This allows for maximal tumor resection with considerable reduction in the risk of post-operative speech and motor deficits. We report our experience of awake craniotomy and cortical stimulation for epilepsy and supratentorial tumors located in and around eloquent areas in a pediatric population (n=10, five females). The presenting symptom was mainly seizures and all children had normal neurological examinations. Neuroimaging showed lesions in the left opercular (n=4) and precentral or peri-sylvian regions (n=6). Three right-sided and seven left-sided awake craniotomies were performed. Two patients had a history of prior craniotomy. All patients had intra-operative mapping for either speech or motor or both using cortical stimulation. The surgical goal for tumor patients was gross total resection, while for all epilepsy procedures, focal cortical resections were completed without any difficulty. None of the patients had permanent post-operative neurologic deficits. The patient with an epileptic focus over the speech area in the left frontal lobe had a mild word finding difficulty post-operatively but this improved progressively. Follow-up ranged from 6 to 27months. Pediatric awake craniotomy with intra-operative mapping is a precise, safe and reliable method allowing for resection of lesions in eloquent areas. Further validations on larger number of patients will be needed to verify the utility of this technique in the pediatric population.
    Journal of Clinical Neuroscience 10/2014; DOI:10.1016/j.jocn.2014.07.013 · 1.32 Impact Factor
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    ABSTRACT: Object Resective surgery is increasingly used in the management of pediatric epilepsy. Frequently, invasive monitoring with subdural electrodes is required to adequately map the epileptogenic focus. The risks of invasive monitoring include the need for 2 operations, infection, and CSF leak. The aim of this study was to evaluate the feasibility and outcomes of resective epilepsy surgery guided by magnetoencephalography (MEG) in children who would have otherwise been candidates for electrode implantation. Methods The authors reviewed the records of patients undergoing resective epilepsy surgery at the Hospital for Sick Children between 2001 and 2010. They identified cases in which resections were based on MEG data and no intracranial recordings were performed. Each patient's chart was reviewed for presentation, MRI findings, MEG findings, surgical procedure, pathology, and surgical outcome. Results Sixteen patients qualified for the study. All patients had localized spike clusters on MEG and most had abnormal findings on MRI. Resection was carried out in each case based on the MEG data linked to neuronavigation and supplemented with intraoperative neuromonitoring. Overall, 62.5% of patients were seizure free following surgery, and 20% of patients experienced an improvement in seizures without attaining seizure freedom. In 2 cases, additional surgery was performed subsequently with intracranial monitoring in attempts to obtain seizure control. Conclusions MEG is a viable alternative to invasive monitoring with intracranial electrodes for planning of resective surgery in carefully selected pediatric patients with localization-related epilepsy. Good candidates for this approach include patients who have a well-delineated, localized spike cluster on MEG that is concordant with findings of other preoperative evaluations and patients with prior brain pathologies that make the implantation of subdural and depth electrodes somewhat problematic.
    Journal of Neurosurgery Pediatrics 09/2014; 14(5):1-6. DOI:10.3171/2014.8.PEDS13640 · 1.37 Impact Factor
  • Journal of Medical Devices 09/2014; 8(3):030917. DOI:10.1115/1.4027038 · 0.62 Impact Factor
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    ABSTRACT: Objective Multiple tubers in patients with tuberous sclerosis complex (TSC) often are responsible for drug-resistant epilepsy. The complexity of the epileptic network formed by multiple tubers complicates localization of the epileptogenic zone that is needed to design a surgical treatment strategy. High frequency oscillations (HFOs) on intracranial video-electroencephalography (IVEEG) may be a valuable surrogate marker for the localization of the epileptogenic zone. The purpose of this study was to test the hypothesis that high occurrence rate (OR) of interictal HFOs can guide the localization of the epileptogenic zone.Methods We analyzed the OR of interictal HFOs at 80–200 Hz (ripples) and >200 Hz (fast ripples, FRs). We divided OR of interictal HFOs between high and low rates by thresholding. We analyzed the correlation between seizure outcomes using Engel classification and the resection ratio of the seizure onset zone (SOZ), and high-OR HFOs using ordinal logistic regression analysis.ResultsWe collected 10 patients. The seizure outcomes resulted in Engel classification I in three patients, II in four, III in one, and IV in two. High-OR ripples (5–57 [mean 29] channels, 1–4 [2.8] lobes) and high-OR FRs (9–66 [mean 27] channels, 1–4 [2.6] lobes) were widely distributed. The resection ratio of SOZ did not show statistically significant correlation with the seizure outcome. The resection ratio of high-OR ripples showed statistically significant correlation with the seizure outcome (p = 0.038). The resection ratio of high-OR FRs showed statistically significant correlation with the seizure outcome (p = 0.048).SignificanceThe multiple extensive zones with high-OR HFOs suggest a complex and widespread epileptic network in patients with TSC. In a subset of TSC patients with drug-resistant epilepsy, resection of cortex with both interictal high-OR FRs and ripples on IVEEG correlated with a good seizure outcome.
    Epilepsia 09/2014; 55(10). DOI:10.1111/epi.12761 · 4.58 Impact Factor
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    ABSTRACT: Neuroendoscopy is technically challenging due to the limited accuracy, dexterity, and reachability of the instruments. Surgical robots offer a potential solution; however, the unique and critically constrained workspace within the ventricle system poses major challenges. We have developed a novel concentric tube endoscopic robot used as a suction/irrigation tool as a solution and implemented it on a validated silicone hydrocephalic brain phantom.
    Neurosurgery 08/2014; 61 Suppl 1:192. DOI:10.1227/01.neu.0000452378.87586.79 · 3.03 Impact Factor
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    ABSTRACT: Object Porencephalic cyst/encephalomalacia (PC/E) is a brain lesion caused by ischemic insult or hemorrhage. The authors evaluated magnetoencephalography (MEG) spike sources (MEGSS) to localize the epileptogenic zone in children with intractable epilepsy secondary to PC/E. Methods The authors retrospectively studied 13 children with intractable epilepsy secondary to PC/E (5 girls and 8 boys, age range 1.8-15 years), who underwent prolonged scalp video-electroencephalography (EEG), MRI, and MEG. Interictal MEGSS locations were compared with the ictal and interictal zones as determined from scalp video-EEG. Results Magnetic resonance imaging showed PC/E in extratemporal lobes in 3 patients, within the temporal lobe in 2 patients, and in both temporal and extratemporal lobes in 8 patients. Magnetoencephalographic spike sources were asymmetrically clustered at the margin of PC/E in all 13 patients. One cluster of MEGSS was observed in 11 patients, 2 clusters in 1 patient, and 3 clusters in 1 patient. Ictal EEG discharges were lateralized and concordant with MEGSS in 8 patients (62%). Interictal EEG discharges were lateralized and concordant with MEGSS hemisphere in 9 patients (69%). Seven patients underwent lesionectomy in addition to MEGSS clusterectomy with (2 patients) and without (5 patients) intracranial video-EEG. Temporal lobectomy was performed in 1 patient and hemispherectomy in another. Eight of 9 patients achieved seizure freedom following surgery. Conclusions Magnetoencephalography delineated the extent of the epileptogenic zone adjacent to PC/E in patients with intractable epilepsy. Complete resection of the MEGSS cluster along with PC/E can provide favorable seizure outcomes.
    Journal of Neurosurgery Pediatrics 07/2014; DOI:10.3171/2014.6.PEDS13415 · 1.37 Impact Factor
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    ABSTRACT: Object The use of endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) has been advocated as an alternative to CSF shunting in infants with hydrocephalus. There are limited reports of this procedure in the North American population, however. The authors provide a retrospective review of the experience with combined ETV + CPC within the North American Hydrocephalus Clinical Research Network (HCRN). Methods All children (< 2 years old) who underwent an ETV + CPC at one of 7 HCRN centers before November 2012 were included. Data were collected retrospectively through review of hospital records and the HCRN registry. Comparisons were made to a contemporaneous cohort of 758 children who received their first shunt at < 2 years of age within the HCRN. Results Thirty-six patients with ETV + CPC were included (13 with previous shunt). The etiologies of hydrocephalus were as follows: intraventricular hemorrhage of prematurity (9 patients), aqueductal stenosis (8), myelomeningocele (4), and other (15). There were no major intraoperative or early postoperative complications. There were 2 postoperative CSF infections. There were 2 deaths unrelated to hydrocephalus and 1 death from seizure. In 18 patients ETV + CPC failed at a median time of 30 days after surgery (range 4-484 days). The actuarial 3-, 6-, and 12-month success for ETV + CPC was 58%, 52%, and 52%. Time to treatment failure was slightly worse for the 36 patients with ETV + CPC compared with the 758 infants treated with shunts (p = 0.012). Near-complete CPC (≥ 90%) was achieved in 11 cases (31%) overall, but in 50% (10 of 20 cases) in 2012 versus 6% (1 of 16 cases) before 2012 (p = 0.009). Failure was higher in children with < 90% CPC (HR 4.39, 95% CI 0.999-19.2, p = 0.0501). Conclusions The early North American multicenter experience with ETV + CPC in infants demonstrates that the procedure has reasonable safety in selected cases. The degree of CPC achieved might be associated with a surgeon's learning curve and appears to affect success, suggesting that surgeon training might improve results.
    Journal of Neurosurgery Pediatrics 07/2014; DOI:10.3171/2014.6.PEDS13492 · 1.37 Impact Factor
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    ABSTRACT: Object Shunt survival may improve when ventricular catheters are placed into the frontal horn or trigone of the lateral ventricle. However, techniques for accurate catheter placement have not been developed. The authors recently reported a prospective study designed to test the accuracy of catheter placement with the assistance of intraoperative ultrasound, but the results were poor (accurate placement in 59%). A major reason for the poor accurate placement rate was catheter movement that occurred between the time of the intraoperative ultrasound image and the first postoperative scan (33% of cases). The control group of non-ultrasound using surgeons also had a low rate of accurate placement (accurate placement in 49%). The authors conducted an exploratory post hoc analysis of patients in their ultrasound study to identify factors associated with either catheter movement or poor catheter placement so that improved surgical techniques for catheter insertion could be developed. Methods The authors investigated the following risk factors for catheter movement and poor catheter placement: age, ventricular size, cortical mantle thickness, surgeon experience, surgeon experience with ultrasound prior to trial, shunt entry site, shunt hardware at entry site, ventricular catheter length, and use of an ultrasound probe guide for catheter insertion. Univariate analysis followed by multivariate logistic regression models were used to determine which factors were independent risk factors for either catheter movement or inaccurate catheter location. Results In the univariate analyses, only age < 6 months was associated with catheter movement (p = 0.021); cortical mantle thickness < 1 cm was near-significant (p = 0.066). In a multivariate model, age remained significant after adjusting for cortical mantle thickness (OR 8.35, exact 95% CI 1.20-infinity). Univariate analyses of factors associated with inaccurate catheter placement showed that age < 6 months (p = 0.001) and a posterior shunt entry site (p = 0.021) were both associated with poor catheter placement. In a multivariate model, both age < 6 months and a posterior shunt entry site were independent risk factors for poor catheter placement (OR 4.54, 95% CI 1.80-11.42, and OR 2.59, 95% CI 1.14-5.89, respectively). Conclusions Catheter movement and inaccurate catheter placement are both more likely to occur in young patients (< 6 months). Inaccurate catheter placement is also more likely to occur in cases involving a posterior shunt entry site than those involving an anterior shunt entry site. Future clinical studies aimed at improving shunt placement techniques must consider the effects of young age and choice of entry site on catheter location.
    Journal of Neurosurgery Pediatrics 06/2014; 14(2):1-6. DOI:10.3171/2014.5.PEDS13481 · 1.37 Impact Factor
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    ABSTRACT: Pediatric laparoscopy poses unique training challenges owing to smaller workspaces, finer sutures used, and potentially more delicate tissues that require increased surgical dexterity when compared with adult analogs. We describe the development and face validation of a pediatric pyeloplasty simulator using a low-cost laparoscopic dry-laboratory model developed with 3-dimensional (3D) printing and silicone modeling. The organs (the kidney, renal pelvis, and ureter) were created in a 3-step process where molds were created with 3D modeling software, printed with a Spectrum Z510 3D printer, and cast with Dragon Skin 30 silicone rubber. The model was secured in a laparoscopy box trainer. A pilot study was conducted at a Canadian Urological Association meeting. A total of 24 pediatric urology fellows and 3 experienced faculty members then assessed our skills module during a minimally invasive surgery training course. Participants had 60 minutes to perform a right-side pyeloplasty using laparoscopic tools and 5-0 VICRYL suture. Face validity was demonstrated on a 5-point Likert scale. The dry-laboratory model consists of a kidney, a replaceable dilated renal pelvis and ureter with an obstructed ureteropelvic junction, and an overlying peritoneum with an inscribed fundamentals of laparoscopic surgery pattern-cutting exercise. During initial validation at the Canadian Urological Association, participants rated (out of 5) 4.75 ± 0.29 for overall impression, 4.50 ± 0.41 for realism, and 4.38 ± 0.48 for handling. During the minimally invasive surgery course, 22 of 24 fellows and all the faculty members completed the scoring. Usability was rated 4 or 5 by 14 participants (overall, 3.6 ± 1.22 by novices and 3.7 ± 0.58 by experts), indicating that they would use the model in their own training and teaching. Esthetically, the model was rated 3.5 ± 0.74 (novices) and 3.3 ± 0.58 (experts). We developed a pediatric pyeloplasty simulator by applying a low-cost reusable model for laparoscopic training and skills acquisition. The model's usability, realism, and feel are good, it can be imaged under common modalities, and it shows promise as an educational tool.
    Journal of Surgical Education 04/2014; 71(5). DOI:10.1016/j.jsurg.2014.03.001 · 1.39 Impact Factor
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    ABSTRACT: The purpose of this study is to develop and evaluate a pediatric patient-specific surgical simulator for the planning, practice, and validation of laparoscopic surgical procedures prior to intervention, initially focusing on the choledochal cyst resection and reconstruction scenario. The simulator is comprised of software elements including a deformable body physics engine, virtual surgical tools, and abdominal organs. Hardware components such as haptics-enabled hand controllers and a representative endoscopic tool have also been integrated. The prototype is able to perform a number of surgical tasks and further development work is under way to simulate the complete procedure with acceptable fidelity and accuracy.
    Studies in health technology and informatics 01/2014; 196:360-4.
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    ABSTRACT: Objectives Pediatric laparoscopy poses unique training challenges owing to smaller workspaces, finer sutures used, and potentially more delicate tissues that require increased surgical dexterity when compared with adult analogs. We describe the development and face validation of a pediatric pyeloplasty simulator using a low-cost laparoscopic dry-laboratory model developed with 3-dimensional (3D) printing and silicone modeling. Design and Setting The organs (the kidney, renal pelvis, and ureter) were created in a 3-step process where molds were created with 3D modeling software, printed with a Spectrum Z510 3D printer, and cast with Dragon Skin 30 silicone rubber. The model was secured in a laparoscopy box trainer. A pilot study was conducted at a Canadian Urological Association meeting. A total of 24 pediatric urology fellows and 3 experienced faculty members then assessed our skills module during a minimally invasive surgery training course. Participants had 60 minutes to perform a right-side pyeloplasty using laparoscopic tools and 5-0 VICRYL suture. Face validity was demonstrated on a 5-point Likert scale. Participants and Results The dry-laboratory model consists of a kidney, a replaceable dilated renal pelvis and ureter with an obstructed ureteropelvic junction, and an overlying peritoneum with an inscribed fundamentals of laparoscopic surgery pattern-cutting exercise. During initial validation at the Canadian Urological Association, participants rated (out of 5) 4.75 ± 0.29 for overall impression, 4.50 ± 0.41 for realism, and 4.38 ± 0.48 for handling. During the minimally invasive surgery course, 22 of 24 fellows and all the faculty members completed the scoring. Usability was rated 4 or 5 by 14 participants (overall, 3.6 ± 1.22 by novices and 3.7 ± 0.58 by experts), indicating that they would use the model in their own training and teaching. Esthetically, the model was rated 3.5 ± 0.74 (novices) and 3.3 ± 0.58 (experts). Conclusions We developed a pediatric pyeloplasty simulator by applying a low-cost reusable model for laparoscopic training and skills acquisition. The model’s usability, realism, and feel are good, it can be imaged under common modalities, and it shows promise as an educational tool.
    Journal of Surgical Education 01/2014; · 1.39 Impact Factor
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    ABSTRACT: Introduction/Background: Theoretically-based research exploring instructional design in healthcare simulation has emerged as a top priority.1-3 In turn, interest in cognitive load theory as a foundation for empirical investigation of instructional design principles in simulation has grown.1,4 An essential precursor to this line of inquiry is the development and evaluation of cognitive load (CL) measures that are appropriate for the healthcare simulation setting. To be effective, these measures should be unintrusive, sensitive to cognitive demands imposed by the simulated task and natural to the performer.5 The objectives of this study were to: 1) develop contextually relevant measures of CL based on secondary-task methodology and 2) generate preliminary validity evidence6 supporting their use in simulation-based psychomotor skills training. It was hypothesized that: 1) these measures of secondary-task performance would be sensitive to variations in CL within novices as cognitive demands change and between novices and experts when performing a psychomotor primary-task, and 2) similar patterns would be observed between experts and novices on subjective measures of cognitive load and primary-task performance. Methods: We developed a virtual vital signs monitor with a built-in visual stimulus detection secondary-task, in which participants monitor a baseline heart-rate and press a foot-pedal each time a pre-determined change (bradycardia or tachycardia) is observedThe software subsequently records two performance metrics: stimulus-detection error rate (SDER) and recognition reaction time (RRT)To evaluate the sensitivity of these metrics to variations in CL during simulation-based psychomotor skills training, five experts (surgical residents) and seven novices (medical students) completed a baseline stimulus-detection trial and a dual-task trial consisting of one-handed surgical knot tying on a part-task trainer, while monitoring for changes in heart-rateFollowing the dual-task trial, participants also completed a subjective rating of mental effort (SRME) using a previously developed scale.7 Primary-task (knot-tying) performance was assessed by total movements (TM) and time to complete (TC) a square knot.8 The first hypothesis was tested by analyzing differences in RRT and SDER from baseline to dual-task between experts and novices, using 2x2 repeated measures ANOVA and the Tukey test for post-hoc comparisonsThe second hypothesis was tested by analyzing differences between experts and novices SRME and on knot-tying performance, using the Kruskal-Wallis test and independent sample t-test respectively. Results: Analysis of secondary-task performance demonstrated a significant interaction between expertise (novice vsexpert) and task (single vsdual-task) for RRT (F(1,10)=9.947, p<0.01, partial eta2=0.89) and SDER (F(1,10)=81.133, p<0.0001, partial eta2=0.89)Pairwise comparisons revealed a significant increase in RRT and SDER from baseline to dual-task among novices (q=6.18, p<0.025 and q=16.45, p<0.01 respectively) but not among expertsIn addition, experts had significantly lower RRT and SDER compared to novices during dual-tasking (q=5.21, p<0.05 and q=14.88, p<0.01 respectively) but not at baselineSimilarly, compared to novices, experts had significantly lower dual-task SRME (chi2=5.316, p<0.021) and superior primary task performance with respect to TC (t=4.939, p<0.004), and TM (t=4.748, p<0.005). Conclusion: We have developed an instrument for assessing CL that employs a contextually relevant secondary task (response to changes in vital signs). The measures generated from this instrument are sensitive to variations in CL among novices as cognitive demands change (i.e. single to dual-tasking) and between novices and experts performing a psychomotor skill. The difference in performance between novices and experts on these measures are similar to those seen on primary task performance (TC and TM) and subjective ratings of cognitive load, demonstrating preliminary validity evidence in the category of "response to other variables"6 for the two CL measures generated by our instrument (RRT and SDER). The Results indicate this instrument may be effective for measuring cognitive load during simulation-based psychomotor skills training of novice learners. References: 1. Issenberg SB, Ringsted C, Ostergaard D, Dieckmann P: Setting a Research Agenda for Simulation-Based Healthcare Education: Simulation in Healthcare 2011; 6(3):155-167. 2. Dieckmann P, Phero JC, Issenberg SB, Kardong-Edgren S, Ostergaard D, Ringsted C: The first Research Consensus Summit of the Society for Simulation in Healthcare: conduction and a synthesis of the Results. Simulation in Healthcare 2011; 6(Suppl):S1-S9. 3. Cook DA, Hamstra SJ, Brydges R, Zendejas B, Szostek JH, Wang AT, Erwin PJ, Hatala R: Comparative effectiveness of instructional design features in simulation-based education: Systematic review and meta-analysis. Medical Teacher 2013; 35(1):e844-75. 4. van Merrienboer JJG, Sweller J: Cognitive load theory in health professional education: design principles and strategies. Medical Education 2010; 44(1):85-93. 5. Carswell C, Clarke D, Seales W: Assessing Mental Workload During Laparoscopic Surgery. Surgical Innovation 2005; 12(1):80-90. 6. Downing S: Validity - on the meaningful interpretation of assessment data. Medical Education 2003; 37:830-837. 7. Paas FG, Van Merrienboer JJG, Adam JJ: Measurement of cognitive load in instructional research. Perceptual and Motor Skills 1994; 79:419-430. 8. Xeroulis G, Park J, Moulton C, Reznick R, LeBlanc V, Dubrowski A: Teaching suturing and knot-tying skills to medical students: A randomized controlled study comparing computer-based video instruction and (concurrent and summary) expert feedback. Surgery 2007; 141(4):442-449. This article can be accessed at: http://journals.lww.com/simulationinhealthcare/Abstract/2013/12000/Board_343___Research_Abstract_Development_and.239.aspx
    Simulation in Healthcare: The Journal of the Society for Simulation in Healthcare; 12/2013
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    ABSTRACT: Object Cerebrospinal fluid shunt ventricular catheters inserted into the frontal horn or trigone are associated with prolonged shunt survival. Developing surgical techniques for accurate catheter insertion could, therefore, be beneficial to patients. This study was conducted to determine if the rate of accurate catheter location with intraoperative ultrasound guidance could exceed 80%. Methods The authors conducted a prospective, multicenter study of children (< 18 years) requiring first-time treatment for hydrocephalus with a ventriculoperitoneal shunt. Using intraoperative ultrasound, surgeons were required to target the frontal horn or trigone for catheter tip placement. An intraoperative ultrasound image was obtained at the time of catheter insertion. Ventricular catheter location, the primary outcome measure, was determined from the first postoperative image. A control group of patients treated by nonultrasound surgeons (conventional surgeons) were enrolled using the same study criteria. Conventional shunt surgeons also agreed to target the frontal horn or trigone for all catheter insertions. Patients were triaged to participating surgeons based on call schedules at each center. A pediatric neuroradiologist blinded to method of insertion, center, and surgeon determined ventricular catheter tip location. Results Eleven surgeons enrolled as ultrasound surgeons and 6 as conventional surgeons. Between February 2009 and February 2010, 121 patients were enrolled at 4 Hydrocephalus Clinical Research Network centers. Experienced ultrasound surgeons (> 15 cases prior to study) operated on 67 patients; conventional surgeons operated on 52 patients. Experienced ultrasound surgeons achieved accurate catheter location in 39 (59%) of 66 patients, 95% CI (46%-71%). Intraoperative ultrasound images were compared with postoperative scans. In 32.7% of cases, the catheter tip moved from an accurate location on the intraoperative ultrasound image to an inaccurate location on the postoperative study. This was the most significant factor affecting accuracy. In comparison, conventional surgeons achieved accurate location in 24 (49.0%) of 49 cases (95% CI [34%-64%]). The shunt survival rate at 1 year was 70.8% in the experienced ultrasound group and 66.9% in the conventional group (p = 0.66). Ultrasound surgeons had more catheters surrounded by CSF (30.8% vs 6.1%, p = 0.0012) and away from the choroid plexus (72.3% vs 58.3%, p = 0.12), and fewer catheters in the brain (3% vs 22.4%, p = 0.0011) and crossing the midline (4.5% vs 34.7%, p < 0.001), but they had a higher proportion of postoperative pseudomeningocele (10.1% vs 3.8%, p = 0.30), wound dehiscence (5.8% vs 0%, p = 0.13), CSF leak (10.1% vs 1.9%, p = 0.14), and shunt infection (11.6% vs 5.8%, p = 0.35). Conclusions Ultrasound-guided shunt insertion as performed in this study was unable to consistently place catheters into the frontal horn or trigone. The technique is safe and achieves outcomes similar to other conventional shunt insertion techniques. Further efforts to improve accurate catheter location should focus on prevention of catheter migration that occurs between intraoperative placement and postoperative imaging. Clinical trial registration no.: NCT01007786 ( ClinicalTrials.gov ).
    Journal of Neurosurgery Pediatrics 10/2013; DOI:10.3171/2013.9.PEDS1346 · 1.37 Impact Factor
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    ABSTRACT: With the need for transparency of surgical results, 30-day outcome measures have become increasingly important. Ventriculoperitoneal (VP) shunt failure is a substantial burden to patients and health care systems. This study introduces the 30-day VP shunt failure rate as a possible barometer of surgical outcome, and demonstrates its use in a national (UK) study and makes comparison with two published randomized controlled trials (RCT). Cohort study of all (bar one) pediatric neurosurgical centers in the UK and Ireland. All new and revision VP shunt operations were recorded for 2008 and 2009. Both newly placed and revised VP shunts were subject to Kaplan Meier analysis, and 30-day failure rate was obtained. Data from two RCTs investigating new VP shunt technology were analyzed and 30-day failure rate was extracted for comparative purposes. The overall 30-day and 1-year failure rate for new shunts was 12.9% and 28.8%, respectively. The 30-day failure rate from two RCTs was comparable (14% and 16%, respectively). The failure rate of the subsequent revision of those new shunts was 20.7% at 30-days and 40.4% at 1-year. According to these data, shunt survival appears to be better if performed by a consultant pediatric neurosurgeon for revision surgery only. VP shunt survival in the UK is comparable to the published multicenter data investigating shunt survival. The 30-day failure rate may represent a better barometer of surgical outcome, and should be used as a separate outcome measure in the design of future trials.
    Neurosurgery 10/2013; 74(1). DOI:10.1227/NEU.0000000000000196 · 3.03 Impact Factor
  • Journal of Neurosurgery Pediatrics 10/2013; 12(4):334-338. DOI:10.3171/2013.7.PEDS12637 · 1.37 Impact Factor
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    ABSTRACT: Cranio-orbital reshaping for anterior cranial-vault deformities associated with craniosynostosis traditionally relies on the surgeon's subjective estimate of the shape and appearance of a normal forehead. Computer-aided design/computer-aided manufacture (CAD/CAM) bandeau templates to guide reconstruction were introduced in our centre to eliminate this subjectivity and to effect more reproducible surgical results. The aim of this study was to compare two groups of patients (template, n = 14 vs. no template, n = 23) to measure surgical outcomes. The virtual, computational version of the template was used as an outcome assessment tool. It was used to calculate an intervening area under the curve (AUC) between the normative template and the patient's reconstructed supra-orbital bar on a representative computed tomography (CT) axial section. A comprehensive chart review was conducted of patients in both groups to examine the preoperative and postoperative variables. Based on the analysis performed on the immediate postoperative CT scans, in the template group - as compared to the control, no-template group - the use of the bandeau template led to a greater reduction in AUC (74% vs. 56%, p = 0.016), indicating a better conformity between the reconstructed supra-orbital bar and the ideal, normal bandeau shape. The duration of operation was significantly reduced with the use of the template (212 vs. 258 min, p < 0.001). The application of prefabricated templates in cranio-orbital reshaping is highly useful for accurate preoperative planning; reproducible and efficient intra-operative correction of dysmorphology; and objective surgical outcomes assessment. Therapeutic Level III.
    Journal of Plastic Reconstructive & Aesthetic Surgery 09/2013; 67(1). DOI:10.1016/j.bjps.2013.09.009 · 1.47 Impact Factor

Publication Stats

6k Citations
569.61 Total Impact Points

Institutions

  • 1991–2014
    • University of Toronto
      • • Division of Neurosurgery
      • • Department of Surgery
      • • Institute of Biomaterials and Biomedical Engineering
      • • Hospital for Sick Children
      Toronto, Ontario, Canada
  • 1988–2014
    • SickKids
      • Division of Neurosurgery
      Toronto, Ontario, Canada
  • 2013
    • Texas Children's Hospital
      Houston, Texas, United States
  • 1989–2012
    • Toronto Western Hospital
      Toronto, Ontario, Canada
  • 2004–2009
    • University of Utah
      • • Primary Children's Medical Center
      • • Department of Neurosurgery
      Salt Lake City, UT, United States
  • 2008
    • University of North Carolina at Chapel Hill
      • Department of Neurosurgery
      Chapel Hill, NC, United States
  • 1994–2008
    • University of Waterloo
      • Department of Applied Mathematics
      Waterloo, Quebec, Canada
  • 2005
    • University of Texas Health Science Center at Houston
      Houston, Texas, United States
  • 2003
    • Mount Sinai Hospital, Toronto
      Toronto, Ontario, Canada
    • Dalhousie University
      • Division of Neurosurgery
      Halifax, Nova Scotia, Canada
  • 2001–2002
    • The Royal Children's Hospital
      • Department of Neurosurgery
      Melbourne, Victoria, Australia