Publications by authors named "James M Drake"

145 Publications

Surgical targeting of large hypothalamic hamartomas and seizure-freedom following MR-guided laser interstitial thermal therapy.

Epilepsy Behav 2021 Feb 4;116:107774. Epub 2021 Feb 4.

Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada; Division of Neurosurgery, Hospital for Sick Children, Department of Surgery, University of Toronto, Toronto, Canada. Electronic address:

Background: Large hypothalamic hamartomas (HH) are often associated with difficult-to-treat, refractory seizures. Although magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a useful tool to treat these challenging lesions, postoperative outcomes are variable and potentially related to differences in surgical targeting.

Purpose: We sought to identify differences in the anatomic localization of laser ablations that either did or did not result in seizure freedom.

Methods: Four children who underwent MRgLITT for large HH (3 seizure-free and 1 not seizure-free) were included in the analysis. Ablation volumes were segmented, normalized, and overlaid on a high-resolution hypothalamic atlas. For each lesion, the size, spatial extent, and degree of overlap with key hypothalamic nuclei and surrounding brain regions were computed and compared between ablations that did and did not result in seizure freedom.

Results: Ablation masks that resulted in seizure freedom were smaller and located more centrally than the ablation mask that did not. In addition, ablation masks that resulted in seizure freedom overlapped with regions including the paraventricular nucleus, the posterior hypothalamus and the zona incerta, fornix, and mammillothalamic tract, whereas the single non-seizure-free ablation did not.

Conclusion: Differences in the size, position, and anatomical localization of ablation volumes may be a potential contributor to the variability in postoperative outcomes of large HH treated with MRgLITT. A novel, high-resolution MRI atlas of the hypothalamus identifies a number of regions at the interface of large HH that are preferentially disconnected in seizure-free patients. This method of anatomical localization not only serves as a potential clinical tool for surgical targeting but may also provide novel insights into the mechanisms of epileptogenesis in hypothalamic hamartomas.
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http://dx.doi.org/10.1016/j.yebeh.2021.107774DOI Listing
February 2021

Timing of temporizing neurosurgical treatment in relation to shunting and neurodevelopmental outcomes in post-hemorrhagic ventricular dilatation of prematurity: a meta-analysis.

J Pediatr 2021 Jan 20. Epub 2021 Jan 20.

Department of Neurological Surgery, McGaw Medical Center of Northwestern University, Chicago, IL, USA; Galter Health Science Library, Northwestern University, Chicago, IL, USA.

Objective: To determine the relationship between timing of initiation of temporizing neurosurgical treatment and rates of ventriculoperitoneal shunting (VPS) and neurodevelopmental impairment in premature infants with post-hemorrhagic ventricular dilatation (PHVD).

Study Design: We searched MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, and Cochrane Center Register of Controlled Trials for studies that reported on premature infants with PHVD who received TNP. Timing of TNP, gestational age, birth weight, and outcomes of conversion to VPS, moderate-to-severe NDI, infection, TNP revision, and death at discharge were extracted.

Results: Sixty-two full-length articles and six conference abstracts (n=2533 patients) published through November 2020 were included. Pooled rate for conversion to VPS was 60.5% (95% CI=54.9-65.8), moderate-severe NDI 34.8% (95% CI=27.4-42.9), infection 8.2% (95% CI=6.7-10.1), revision 14.6% (95% CI=10.4-20.1), and death 12.9% (95% CI=10.2-16.4). Average age at TNP was 24.2+/-11.3 days. On meta-regression, older age at TNP was a predictor of conversion to VPS (p<0.001) and NDI (p<0.01). Later year of publication predicted increased survival (p<0.01) and external ventricular drains were associated with more revisions (p=0.001). Tests for heterogeneity reached significance for all outcomes and qualitative review showed heterogeneity in study inclusion and diagnosis criteria for PHVD and initiation of TNP.

Conclusions: Later timing of TNP predicted higher rates of conversion to VPS and moderate-severe NDI. Outcomes were often reported relative to number of patients who received TNP and criteria for study inclusion and initiation of TNP varied across institutions. There is need for more comprehensive outcome reporting that includes all infants with PHVD regardless of treatment.
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http://dx.doi.org/10.1016/j.jpeds.2021.01.030DOI Listing
January 2021

Temporal trends in surgical procedures for pediatric hydrocephalus: an analysis of the Hydrocephalus Clinical Research Network Core Data Project.

J Neurosurg Pediatr 2020 Dec 18:1-8. Epub 2020 Dec 18.

9Department of Clinical Neurosciences, Alberta Children's Hospital, University of Calgary, Alberta, Canada.

Objective: Analysis of temporal trends in patient populations and procedure types may provide important information regarding the evolution of hydrocephalus treatment. The purpose of this study was to use the Hydrocephalus Clinical Research Network's Core Data Project to identify meaningful trends in patient characteristics and the surgical management of pediatric hydrocephalus over a 9-year period.

Methods: The Core Data Project prospectively collected patient and procedural data on the study cohort from 9 centers between 2008 and 2016. Logistic and Poisson regression were used to test for significant temporal trends in patient characteristics and new and revision hydrocephalus procedures.

Results: The authors analyzed 10,149 procedures in 5541 patients. New procedures for hydrocephalus (shunt or endoscopic third ventriculostomy [ETV]) decreased by 1.5%/year (95% CI -3.1%, +0.1%). During the study period, new shunt insertions decreased by 6.5%/year (95% CI -8.3%, -4.6%), whereas new ETV procedures increased by 12.5%/year (95% CI 9.3%, 15.7%). Revision procedures for hydrocephalus (shunt or ETV) decreased by 4.2%/year (95% CI -5.2%, -3.1%), driven largely by a decrease of 5.7%/year in shunt revisions (95% CI -6.8%, -4.6%). Concomitant with the observed increase in new ETV procedures was an increase in ETV revisions (13.4%/year, 95% CI 9.6%, 17.2%). Because revisions decreased at a faster rate than new procedures, the Revision Quotient (ratio of revisions to new procedures) for the Network decreased significantly over the study period (p = 0.0363). No temporal change was observed in the age or etiology characteristics of the cohort, although the proportion of patients with one or more complex chronic conditions significantly increased over time (p = 0.0007).

Conclusions: Over a relatively short period, important changes in hydrocephalus care have been observed. A significant temporal decrease in revision procedures amid the backdrop of a more modest change in new procedures appears to be the most notable finding and may be indicative of an improvement in the quality of surgical care for pediatric hydrocephalus. Further studies will be directed at elucidation of the possible drivers of the observed trends.
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http://dx.doi.org/10.3171/2020.7.PEDS20142DOI Listing
December 2020

Manual Shunt Connector Tool to Aid in No-Touch Technique.

Oper Neurosurg (Hagerstown) 2021 Jan;20(2):183-188

Division of Neurosurgery, Hospital for Sick Children, Toronto, Canada.

Background: Given the morbidity and cost associated with cerebrospinal fluid shunt infections, many neurosurgical protocols implement "no-touch" technique to minimize infection. However, current surgical tools are not designed specifically for this task and surgeons often resort to using their hands to connect the shunt catheter to the valve.

Objective: To develop an efficient and effective shunt assembly tool.

Methods: Prototypes were designed using computer assisted software and machined in stainless steel. The amount of time and number of attempts it took volunteers to connect a Bacticel shunt catheter to a Delta valve were recorded using the new tool and standard shodded mosquitos. Scanning electron microscopy (SEM) was done on manipulated catheters to assess potential damage. Practicing neurosurgeons provided feedback.

Results: Nonsurgeon (n = 13) volunteers and neurosurgeons (n = 6) both completed the task faster and with fewer attempts with the new tool (mean 7.18 vs 15.72 s and 2.00 vs 6.36 attempts, P < .0001; mean 2.93 vs 5.96 s and 1.06 vs 2.94 attempts, P < .001, respectively). SEM of 24 manipulated catheters showed no microscopic damage. 100% of neurosurgeons surveyed (n = 10) would adapt the tool in their practice, 90% preferred use of the new tool compared to their existing method, and 100% rated it easier to use compared to existing instruments.

Conclusion: The new tool shortened the time and number of attempts to connect a shunt catheter to a valve. Neurosurgeons preferred the new tool to existing instruments. There was no evidence of catheter damage with the use of this tool.
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http://dx.doi.org/10.1093/ons/opaa284DOI Listing
January 2021

Fetal spina bifida: What we tell the parents.

Prenat Diagn 2020 12 22;40(12):1499-1507. Epub 2020 Aug 22.

Department of Obstetrics and Gynaecology, Mount Sinai Hospital and University of Toronto, Toronto, Canada.

Worldwide, about 150 000 infants are born with spina bifida yearly, making this condition one of the most common fetal central nervous system anomalies compatible with life. Over the last decade, major changes have been introduced in the prenatal diagnosis and management of spina bifida. In this review, we provide a brief summary of the current management of fetal spina bifida and present essential information that should be provided to expecting parents when their fetus has been diagnosed with spina bifida. This information is focused around common parental questions, as encountered in our typical clinical practice, to facilitate knowledge translation.
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http://dx.doi.org/10.1002/pd.5802DOI Listing
December 2020

Traumatic atlanto-occipital dislocation in children: is external immobilization an option?

Childs Nerv Syst 2021 Jan 9;37(1):177-183. Epub 2020 Jun 9.

Division of Neurosurgery, The Hospital for Sick Children, Toronto, Canada.

Object: Traumatic atlanto-occipital dislocation (AOD) is a relatively uncommon traumatic cervical spine injury characterized by disruption and instability of the atlanto-occipital joint. At many centers, management of pediatric AOD includes occipitocervical arthrodesis, but whether external immobilization without surgery is a viable treatment option for some pediatric patients is unknown. To answer this question, we analyzed our outcomes of pediatric AOD at the Hospital for Sick Children.

Methods: We performed a retrospective chart review of all children with clinical and radiographic evidence of traumatic AOD. A total of 10 patients met criteria for traumatic AOD: 8 were treated with external immobilization alone and 2 were treated with occipitocervical arthrodesis.

Results: Eight patients were treated exclusively with 3 months of halo immobilization. Two patients were treated with occipitocervical instrumentation and arthrodesis. No patient undergoing halo immobilization required subsequent operative fusion.

Conclusion: Halo immobilization is a safe, viable, and definitive treatment option for the selected children with AOD.
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http://dx.doi.org/10.1007/s00381-020-04680-wDOI Listing
January 2021

Assessing Performance in Simulated Cleft Palate Repair Using a Novel Video Recording Setup.

Cleft Palate Craniofac J 2020 06;57(6):687-693

Division of Plastic & Reconstructive Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.

Objective: To test the feasibility of implementing a high-fidelity cleft palate simulator during a workshop in Santiago, Chile, using a novel video endoscope to assess technical performance.

Design: Sixteen cleft surgeons from South America participated in a 2-day cleft training workshop. All 16 participants performed a simulated repair, and 13 of them performed a second simulated repair. The repairs were recorded using a low-cost video camera and a newly designed camera mouth retractor attachment. Twenty-nine videos were assessed by 3 cleft surgeons using a previously developed cleft palate objective structured assessment of technical skill (CLOSATS with embedded overall score assessment) and global rating scale. The reliability of the ratings and technical performance in relation to minimum acceptable scores and previous experience was assessed.

Results: The video setup provided acceptable recording quality for the purpose of assessment. Average intraclass correlation coefficient for the CLOSATS, global, and overall performance score was 0.69, 0.75, and 0.82, respectively. None of the novice surgeons passed the CLOSATS and global score for both sessions. One participant in the intermediate group, and 2 participants in the advanced group passed the CLOSATS and global score for both sessions. There were highly experienced participants who failed to pass the CLOSATS and global score for both sessions.

Conclusions: The cleft palate simulator can be practically implemented with video-recording capability to assess performance in cleft palate repair. This technology may be of assistance in assessing surgical competence in cleft palate repair.
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http://dx.doi.org/10.1177/1055665620913178DOI Listing
June 2020

Letter to the Editor. The fallacy of sunk cost: decision-making after intrauterine myelomeningocele repair.

J Neurosurg Pediatr 2020 May 8:1-2. Epub 2020 May 8.

2The Hospital for Sick Children, Toronto, ON, Canada.

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http://dx.doi.org/10.3171/2020.3.PEDS20195DOI Listing
May 2020

Health care transition in pediatric neurosurgery: a consensus statement from the American Society of Pediatric Neurosurgeons.

J Neurosurg Pediatr 2020 Feb 14:1-9. Epub 2020 Feb 14.

9Department of Surgery, Division of Neurosurgery, Connecticut Children's Medical Center, Hartford, Connecticut.

Objective: The number of children with complex medical conditions surviving to adulthood is increasing. A planned transition to adult care systems is essential to the health maintenance of these patients. Guidance has been established for the general health care transition (HCT) from adolescence to adulthood. No formal assessment of the performance of pediatric neurosurgeons in HCT has been previously performed. No "best practice" for this process in pediatric neurosurgery currently exists. The authors pursued two goals in this paper: 1) define the current state of HCT in pediatric neurosurgery through a survey of the membership of the American Society of Pediatric Neurosurgeons (ASPN) on current methods of HCT, and 2) develop leadership-endorsed best-practice guidelines for HCT from pediatric to adult neurosurgical health care.

Methods: Completion of the Current Assessment of Health Care Transition Activities survey was requested of 178 North American pediatric neurosurgeons by using a web-based questionnaire to capture HCT practices of the ASPN membership. The authors concurrently conducted a PubMed/MEDLINE-based literature review of HCT for young adults with special health care needs, surgical conditions, and/or neurological conditions for the period from 1990 to 2018. Selected articles were assembled and reviewed by subject matter experts and members of the ASPN Quality, Safety, and Advocacy Committee. Best-practice recommendations were developed and subjected to peer review by external expert groups.

Results: Seventy-six responses to the survey (43%) were received, and 62 respondents (82%) answered all 12 questions. Scores of 1 (lowest possible score) were recorded by nearly 60% of respondents on transition policy, by almost 70% on transition tracking, by 85% on transition readiness, by at least 40% on transition planning as well as transfer of care, and by 53% on transition completion. Average responses on all core elements were < 2 on the established 4-point scale. Seven best-practice recommendations were developed and endorsed by the ASPN leadership.

Conclusions: The majority of pediatric neurosurgeons have transition practices that are poor, do not meet the needs of patients and families, and should be improved. A structured approach to transition, local engagement with adult neurosurgical providers, and national partnerships between pediatric and adult neurosurgery organizations are suggested to address current gaps in HCT for patients served by pediatric neurosurgeons.
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http://dx.doi.org/10.3171/2019.12.PEDS19524DOI Listing
February 2020

Acute MR-Guided High-Intensity Focused Ultrasound Lesion Assessment Using Diffusion-Weighted Imaging and Histological Analysis.

Front Neurol 2019 15;10:1069. Epub 2019 Oct 15.

Institute of Medical Science, University of Toronto, Toronto, ON, Canada.

The application of magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of neurological conditions has been of increasing interest. Conventional MR imaging can provide structural information about the effect of MRgFUS, where differences in ablated tissue can be seen, but it lacks information about the status of the cellular environment or neural microstructure. We investigate acute changes in water diffusion and white matter tracts in the brain of a piglet model after MRgFUS treatment using diffusion-weighted imaging (DWI) with histological verification of treatment-related changes. MRgFUS was used to treat the anterior body of the fornix in four piglets. T1 and diffusion-weighted images were collected before and after treatment. Mean diffusion-weighted imaging (MDWI) images were generated to measure lesion volumes via signal intensity thresholds. Histological data were collected for volume comparison and assessment of treatment effect. DWI metric maps of fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) were generated for quantitative assessment. Fornix-related fiber tracts were generated before and after treatment for qualitative assessment. The volume of treated tissue measured via MDWI did not differ significantly from histological measurements, and both were significantly larger than the treatment cell volume. Diffusion metrics in the treatment region were significantly decreased following MRgFUS treatment, with the peak change seen at the lesion core and decreasing radially. Histological analysis confirmed an area of coagulative necrosis in the targeted region with sharp demarcation zone with surrounding brain. Tractography from the lesion core and the fornix revealed fiber disruptions following treatment. Diffusion maps and fiber tractography are an effective method for assessing lesion volumes and microstructural changes following MRgFUS treatment. This study demonstrates that DWI has the potential to advance MRgFUS by providing convenient microstructural lesion and fiber tractography assessment after treatment.
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http://dx.doi.org/10.3389/fneur.2019.01069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6803785PMC
October 2019

Intrathecal baclofen versus selective dorsal rhizotomy for children with cerebral palsy who are nonambulant: a systematic review.

J Neurosurg Pediatr 2019 Oct 18:1-9. Epub 2019 Oct 18.

1Division of Neurosurgery, Department of Surgery, and.

Objective: Cerebral palsy (CP) is the most common childhood physical disability. Historically, children with hypertonia who are nonambulatory (Gross Motor Function Classification System [GMFCS] level IV or V) were considered candidates for intrathecal baclofen (ITB) therapy to facilitate care and mitigate discomfort. Selective dorsal rhizotomy (SDR) was often reserved for ambulant children to improve gait. Recently, case series have suggested SDR as an alternative to ITB in selected children functioning at GMFCS level IV/V. The objective for this study was to systematically review the evidence for ITB and SDR in GMFCS level IV or V children.

Methods: Medline, Embase, Web of Science, and Cochrane databases were systematically searched. Articles were screened using the following inclusion criteria: 1) peer-reviewed articles reporting outcomes after SDR or ITB; 2) outcomes reported using a quantifiable scale or standardized outcome measure; 3) patients were < 19 years old at the time of operation; 4) patients had a diagnosis of CP; 5) patients were GMFCS level IV/V or results were reported based on GMFCS status and included some GMFCS level IV/V patients; 6) article and/or abstract in English; and 7) primary indication for surgery was hypertonia. Included studies were assessed with the Risk of Bias in Non-Randomized Studies - of Interventions (ROBINS-I) tool.

Results: Twenty-seven studies met inclusion criteria. The most commonly reported outcomes were spasticity (on the Mean Ashworth Scale) and gross motor function (using the Gross Motor Function Measure), although other outcomes including frequency of orthopedic procedures and complications were also reported. There is evidence from case series that suggests that both ITB and SDR can lower spasticity and improve gross motor function in this nonambulatory population. Complication rates are decidedly higher after ITB due in part to the ongoing risk of device-related complications. The heterogeneity among study design, patient selection, outcome selection, and follow-up periods was extremely high, preventing meta-analysis. There are no comparative studies, and meaningful health-related quality of life outcomes such as care and comfort are lacking. This review is limited by the high risk of bias among included studies. Studies of SDR or ITB that did not clearly describe patients as being GMFCS level IV/V or nonambulatory were excluded.

Conclusions: There is a lack of evidence comparing the outcomes of ITB and SDR in the nonambulatory CP population. This could be overcome with standardized prospective studies using more robust methodology and relevant outcome measures.
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http://dx.doi.org/10.3171/2019.8.PEDS19282DOI Listing
October 2019

Acute ex vivo changes in brain white matter diffusion tensor metrics.

PLoS One 2019 26;14(9):e0223211. Epub 2019 Sep 26.

Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.

Purpose: Diffusion magnetic resonance imaging and tractography has an important role in the visualization of brain white matter and assessment of tissue microstructure. There is a lack of correspondence between diffusion metrics of live tissue, ex vivo tissue, and histological findings. The objective of this study is to elucidate this connection by determining the specific diffusion alterations between live and ex vivo brain tissue. This may have an important role in the incorporation of diffusion imaging in ex vivo studies as a complement to histological sectioning as well as investigations of novel neurosurgical techniques.

Methods: This study presents a method of high angular resolution diffusion imaging and tractography of intact and non-fixed ex vivo piglet brains. Most studies involving ex vivo brain specimens have been formalin-fixed or excised from their original biological environment, processes both of which are known to affect diffusion parameters. Thus, non-fixed ex vivo tissue is used. A region-of-interest based analysis of diffusion tensor metrics are compared to in vivo subjects in a selection of major white matter bundles in order to assess the translatability of ex vivo diffusion measurements.

Results: Tractography was successfully achieved in both in vivo and ex vivo groups. No significant differences were found in tract connectivity, average streamline length, or apparent fiber density. Significantly decreased diffusivity (mean, axial, and radial; p<0.0005) in the non-fixed ex vivo group and unaltered fractional anisotropy (p>0.059) between groups were observed.

Conclusion: This study validates the extrapolation of non-fixed fractional anisotropy measurements to live tissue and the potential use of ex vivo tissue for methodological development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223211PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6762128PMC
April 2020

Development and evaluation of a patient-specific surgical simulator for endoscopic colloid cyst resection.

J Neurosurg 2019 Jun 28:1-9. Epub 2019 Jun 28.

1Center for Image Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto.

Objective: Endoscopic resection of third-ventricle colloid cysts is technically challenging due to the limited dexterity and visualization provided by neuroendoscopic instruments. Extensive training and experience are required to master the learning curve. To improve the education of neurosurgical trainees in this procedure, a synthetic surgical simulator was developed and its realism, procedural content, and utility as a training instrument were evaluated.

Methods: The simulator was developed based on the neuroimaging (axial noncontrast CT and T1-weighted gadolinium-enhanced MRI) of an 8-year-old patient with a colloid cyst and hydrocephalus. Image segmentation, computer-aided design, rapid prototyping (3D printing), and silicone molding techniques were used to produce models of the skull, brain, ventricles, and colloid cyst. The cyst was filled with a viscous fluid and secured to the roof of the third ventricle. The choroid plexus and intraventricular veins were also included. Twenty-four neurosurgical trainees performed a simulated colloid cyst resection using a 30° angled endoscope, neuroendoscopic instruments, and image guidance. Using a 19-item feedback survey (5-point Likert scales), participants evaluated the simulator across 5 domains: anatomy, instrument handling, procedural content, perceived realism, and confidence and comfort level.

Results: Participants found the simulator's anatomy to be highly realistic (mean 4.34 ± 0.63 [SD]) and appreciated the use of actual instruments (mean 4.38 ± 0.58). The procedural content was also rated highly (mean 4.28 ± 0.77); however, the perceived realism was rated slightly lower (mean 4.08 ± 0.63). Participants reported greater confidence in their ability to perform an endoscopic colloid cyst resection after using the simulator (mean 4.45 ± 0.68). Twenty-three participants (95.8%) indicated that they would use the simulator for additional training. Recommendations were made to develop complex case scenarios for experienced trainees (normal-sized ventricles, choroid plexus adherent to cyst wall, bleeding scenarios) and incorporate advanced instrumentation such as side-cutting aspiration devices.

Conclusions: A patient-specific synthetic surgical simulator for training residents and fellows in endoscopic colloid cyst resection was successfully developed. The simulator's anatomy, instrument handling, and procedural content were found to be realistic. The simulator may serve as a valuable educational tool to learn the critical steps of endoscopic colloid cyst resection, develop a detailed understanding of intraventricular anatomy, and gain proficiency with bimanual neuroendoscopic techniques.
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http://dx.doi.org/10.3171/2019.4.JNS183184DOI Listing
June 2019

A study on observed ultrasonic motor-induced magnetic resonance imaging (MRI) artifacts.

Biomed J 2019 04 6;42(2):116-123. Epub 2019 May 6.

Institute of Biomaterials and Biomedical Engineering, Engineering Service Inc. University of Toronto, Toronto, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada.

Background: The safe performance of magnetic resonance imaging (MRI)-guided robot-assisted interventions requires full control and high precision of assistive devices. Because many currently available tools are not MRI-compatible, the characterization of existing tools and development of new ones are necessary. The purpose of this research is to identify and minimize the image artifacts generated by a USM in MR images.

Methods: The behavior of an ultrasonic motor (USM), the most common MRI-safe actuator, in a high-field scanner was investigated. The motor was located in three orientations with respect to the bore axis with the power on or off. The induced image artifacts were compared across four sequences. Three artifact reduction methods (employing ultrashort sequences, slice thickness reductions, and bandwidth increments) were tested.

Results: Signal voids, pileups, and geometric distortions were observed when the motor was off. The artifact size was minimal when the motor shaft was aligned with the bore axis. In addition to the above artifacts, zipper and motion artifacts were noted when the motor was running, and these artifacts increased with increasing motor speed. Increasing the bandwidth slightly reduced the artifacts. However, decreasing the slice thickness from 5 mm to 3 mm and from 5 mm to 1 mm reduced artifact size from 30% to 40% and from 60% to 75%, respectively.

Conclusion: The image artifacts were due to the non-homogenous nature of the static and gradient fields caused by the motor structure. The operating motor interferes with the RF field, causing zipper and motion artifacts.
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http://dx.doi.org/10.1016/j.bj.2018.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6541879PMC
April 2019

Noninvasive ablation of rabbit fetal and placental tissue targets in utero using magnetic resonance-guided high-intensity focused ultrasound.

Prenat Diagn 2019 04 28;39(5):394-402. Epub 2019 Mar 28.

Centre for Image Guided Innovation and Therapeutic Intervention, Hospital for Sick Children, Toronto, Canada.

Objective: Magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) is a potential noninvasive therapy for fetal conditions. In utero MRgHIFU delivery and proton resonance frequency shift (PRFS) thermometry monitoring will control accuracy of HIFU ablation and confirm in situ tissue heating in a rabbit model.

Methods: High-resolution 3T MR images were acquired in late-gestation rabbits (approximately 30 days, n = 5). HIFU sonications, using magnetic resonance (MR) thermometry as a guide, were delivered to achieve necrosis in relevant fetal targets. Thermometry, posttreatment magnetic resonance imaging (MRI), and follow-up histology confirmed ablation.

Results: Placentas (n = 14) were treated with 127 ± 34 Wac; thermometry-indicated temperatures reached 67°C. Lungs (n = 8) were treated with 85 ± 15 Wac and reached 73°C, livers (n = 6) with 80 ± 15 Wac and reached 74°C, and kidneys (n = 5) with 100 Wac and reached 66°C. Histological changes showed focal areas of necrosis with circumferential hemorrhage and/or vasodilation, which transitioned abruptly to healthy tissue.

Conclusion: MRgHIFU therapy can effectively target and thermally treat specific in utero organs in this acute fetal rabbit model. PRFS gives in situ temperature control of therapy on tissues. Conceivably, MRgHIFU therapy may be applicable to specific fetal organ anomalies clinically and has the potential to improve the overall fetal outcome over traditional invasive surgical procedures.
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http://dx.doi.org/10.1002/pd.5443DOI Listing
April 2019

Reply: Evaluation and Implementation of a High-Fidelity Cleft Palate Simulator.

Plast Reconstr Surg 2018 12;142(6):980e-981e

Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.

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http://dx.doi.org/10.1097/PRS.0000000000005031DOI Listing
December 2018

A High Fidelity Cleft Lip Simulator.

Plast Reconstr Surg Glob Open 2018 Sep 5;6(9):e1871. Epub 2018 Sep 5.

Division of Plastic & Reconstructive Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.

Background: Cleft lip surgery is technically difficult requiring precise planning and understanding of 3-dimensional structures to obtain an optimal outcome. A physical cleft lip simulator was developed that allows trainees to gain experience in cleft lip repair and primary rhinoplasty before operating on real patients.

Methods: A cleft lip simulator that comprises multilayered soft tissues, bone, and realistic dissection planes was developed using 3D printing, adhesive and polymer techniques. Four experienced cleft surgeons performed a total of 7 simulated repairs on the simulator. Feedback on the realism and value of the simulator was obtained from the surgeons.

Results: Six of the repairs were a Fisher anatomic subunit approximation technique, and 1 was a rotation advancement repair. All repairs were completed with successful performance of markings, incisions, dissections, and multilayered closure. All surgeons agreed that the simulator is realistic and that the simulator is a valuable tool for training in cleft lip surgery.

Conclusions: A cleft lip simulator that allows performance of a cleft lip repair and primary rhinoplasty from start to finish was developed and pilot tested. The simulator provides a training platform to gain experience in cleft lip repair before operating on real patients.
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http://dx.doi.org/10.1097/GOX.0000000000001871DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6191228PMC
September 2018

Intra-operative cortical motor mapping using subdural grid electrodes in children undergoing epilepsy surgery evaluation and comparison with the conventional extra-operative motor mapping.

Clin Neurophysiol 2018 12 12;129(12):2642-2649. Epub 2018 Aug 12.

Epilepsy Program, Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address:

Objectives: The objective of this study was to review our experience with intra-operative "train of five" stimulation using subdural grid for motor mapping in children undergoing epilepsy surgery evaluation.

Methods: Twenty consecutive children below 18-years of age with drug-refractory epilepsy who underwent invasive-EEG monitoring using subdural-grid placement and intra-operative motor mapping using direct cortical stimulation by sub-dural grid electrodes (IODCS-SDG) at our institution between January-2016 and June-2017 were reviewed. Stimulation was delivered through the subdural-grid electrodes using a train-of-five pulses and muscle responses were recorded by motor-evoked-potentials (MEPs). Intra-operative direct cortical stimulation delivered through a ball-tipped probe (IODCS-probe) and extra-operative motor-mapping (EODCS-SDG) were also performed.

Results: IODCS-SDG was completed in 20 patients and subsequent EODCS-SDG was done in 17/20 patients. MEP responses were more commonly obtained in the deltoid (19/20), extensor-digitorum-communis (20/20) and first-dorsal-interosseus (19/20). The median thresholds varied between 40 V and 60 V for the six muscle groups. The respective IODCS-probe thresholds tended to be similar. No stimulation-provoked seizures or anaesthesia-related complications were noted during IODCS-SDG. EODCS-SDG could not be completed in 4/17 children and mapping data obtained was frequently inadequate. Nine patients demonstrated 100% concordance between IODCS-SDG and EODCS-SDG for the common mapped body regions. Stimulation-provoked seizures during EODCS-SDG were seen in 6/17 (35.3%) and after-discharges in 7/17 (41.2%) children.

Conclusions: IODCS-SDG could be performed safely in children with drug refractory epilepsy undergoing invasive EEG monitoring.

Significance: IODCS-SDG may be a useful adjunct to EODCS-SDG in motor mapping for children.
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http://dx.doi.org/10.1016/j.clinph.2018.07.022DOI Listing
December 2018

Economy of Hand Motion During Cleft Palate Surgery Using a High-Fidelity Cleft Palate Simulator.

Cleft Palate Craniofac J 2019 04 9;56(4):432-437. Epub 2018 Aug 9.

4 Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.

Objective: The objectives of this study were to assess economy of hand motion of residents, fellows, and staff surgeons using a high-fidelity cleft palate simulator to (1) stratify performance for the purpose of simulator validation and (2) to estimate the learning curve.

Design: Two residents, 2 fellows, and 2 staff surgeons performed cleft palate surgery on a high-fidelity cleft palate simulator while their hand motion was tracked using an electromagnetic hand sensor. The time, number of hand movements, and path length of their hands were determined for 10 steps of the procedure. The magnitude of these metrics was compared among the 3 groups of participants and utilized to estimate the learning curve using curve-fitting analysis.

Results: The residents required the most time, number of hand movements, and path length to complete the procedure. Although the number of hand movements was closely matched between the fellows and staff, the overall total path length was shorter for the staff. Inverse curves were fit to the data to represent the learning curve and 25 and 113 simulation sessions are required to reach within 5% and 1% of the expert level, respectively.

Conclusion: The simulator successfully stratified performance using economy of hand motion. Path length is better matched to previous level of experience compared to time or number of hand movements.
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http://dx.doi.org/10.1177/1055665618793768DOI Listing
April 2019

Motion compensation using principal component analysis and projection onto dipole fields for abdominal magnetic resonance thermometry.

Magn Reson Med 2019 01 29;81(1):195-207. Epub 2018 Jul 29.

Centre for Image Guided Innovation and Therapeutic Intervention, Hospital for Sick Children, Toronto, Ontario, Canada.

Purpose: High intensity focused ultrasound (HIFU) has the potential to locally and non-invasively treat cancer with fewer side effects than alternative therapies. However, motion and tissue heterogeneity in the abdomen can compromise the HIFU focus and confound current thermometry methods.

Methods: The proposed thermometry method combines principal component analysis (PCA), as a multi-baseline technique, and projection onto dipole fields (PDF), as a near-referenceless method. PCA forgoes tracking tools by projecting incoming images onto a subspace spanning the motion history. PDF is subsequently used to synthesize the naturally feasible components of the residual phase using a magnetic dipole model. This leaves only the phase shifts that are induced by HIFU.

Results: With in vivo measurements, in porcine and human kidneys, the mean pixel-wise temperature SD was 0.86 ± 0.41°C in selected regions of interest (ROIs) across all data sets, without any user-interaction or supplementary tracking tools. This is an improvement over a benchmark hybrid method, which scored 1.36 ± 1.20°C on the same data. Uncorrected subtraction of the data yielded a score of 3.02 ± 2.87°C.

Conclusion: The PCA-PDF hybrid method achieves superior artifact correction by exploiting the motion history and intrinsic magnetic susceptibility of the underlying tissue.
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http://dx.doi.org/10.1002/mrm.27368DOI Listing
January 2019

Utilization of a robotic mount to determine the force required to cut palatal tissue.

J Mech Behav Biomed Mater 2018 10 6;86:433-439. Epub 2018 Jun 6.

Division of Plastic & Reconstructive Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.

Determination of the material properties of soft tissue is a growing area of interest that aids in the development of new surgical tools and surgical simulators. This study first aims to develop a robot-operated tissue testing system for determination of tissue cutting forces. Second, this system was used to ascertain the cutting properties of the hard and soft palate mucosa and soft palate musculature for the purpose of developing a robotic instrument for cleft palate surgery and a cleft-specific surgical simulator. The palate tissue was cut with a 15 blade mounted to the robot with varying angles (30°, 60°, 90°) and speeds (1.5, 2.5, 3.5 cm/s) of cutting to imitate typical operative tasks. The cutting force range for hard palate mucosa, soft palate mucosa and soft palate muscle were 0.98-3.30, 0.34-1.74 and 0.71-2.71 N, respectively. The break-in force of the cut (i.e. force required for the blade to penetrate the tissue) is significantly impacted by the angle of the blade relative to the tissue rather than the cutting speed. Furthermore, the total surface area of the tissue in contact with the blade during the cut has a significant impact on the total force expended on the tissue.
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http://dx.doi.org/10.1016/j.jmbbm.2018.06.010DOI Listing
October 2018

A systematic review and meta-analysis of endoscopic versus open treatment of craniosynostosis. Part 1: the sagittal suture.

J Neurosurg Pediatr 2018 Oct 6;22(4):352-360. Epub 2018 Jul 6.

1Division of Neurosurgery, Department of Surgery, University of Toronto.

Objective: In this systematic review and meta-analysis the authors aimed to directly compare open surgical and endoscope-assisted techniques for the treatment of sagittal craniosynostosis, focusing on the outcomes of blood loss, transfusion rate, length of stay, operating time, complication rate, cost, and cosmetic outcome.

Methods: A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from 3 electronic databases (MEDLINE, EMBASE, and CENTRAL [Cochrane Central Register of Controlled Trials]) from their inception to August 2017. The quality of methodology and bias risk were assessed using the Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies. Effect estimates between groups were calculated as standardized mean differences with 95% CIs. Random and fixed effects models were used to estimate the overall effect.

Results: Of 316 screened records, 10 met the inclusion criteria, of which 3 were included in the meta-analysis. These studies reported on 303 patients treated endoscopically and 385 patients treated with open surgery. Endoscopic surgery was associated with lower estimated blood loss (p < 0.001), shorter length of stay (p < 0.001), and shorter operating time (p < 0.001). From the literature review of the 10 studies, transfusion rates for endoscopic procedures were consistently lower, with significant differences in 4 of 6 studies; the cost was lower, with differences ranging from $11,603 to $31,744 in 3 of 3 studies; and the cosmetic outcomes were equivocal (p > 0.05) in 3 of 3 studies. Finally, endoscopic techniques demonstrated complication rates similar to or lower than those of open surgery in 8 of 8 studies.

Conclusions: Endoscopic procedures are associated with lower estimated blood loss, operating time, and days in hospital. Future long-term prospective registries may establish advantages with respect to complications and cost, with equivalent cosmetic outcomes. Larger studies evaluating patient- or parent-reported satisfaction and optimal timing of intervention as well as heterogeneity in outcomes are indicated.
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http://dx.doi.org/10.3171/2018.4.PEDS17729DOI Listing
October 2018

A systematic review of endoscopic versus open treatment of craniosynostosis. Part 2: the nonsagittal single sutures.

J Neurosurg Pediatr 2018 Oct 6;22(4):361-368. Epub 2018 Jul 6.

1Division of Neurosurgery, Department of Surgery, University of Toronto.

Objective: Despite increasing adoption of endoscopic techniques for repair of nonsagittal single-suture craniosynostosis, the efficacy and safety of the procedure relative to established open approaches are unknown. In this systematic review the authors aimed to directly compare open surgical and endoscope-assisted techniques for the treatment of metopic, unilateral coronal, and lambdoid craniosynostosis, with an emphasis on quantitative reported outcomes.

Methods: A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from 3 electronic databases (MEDLINE, EMBASE, and CENTRAL [Cochrane Central Register of Controlled Trials]) from their inception to August 2017. The quality of methodology and bias risk were assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies.

Results: Of 316 screened records, 7 studies were included in a qualitative synthesis of the evidence, of which none were eligible for meta-analysis. These reported on 111 unique patients with metopic, 65 with unilateral coronal, and 12 with lambdoid craniosynostosis. For all suture types, 100 (53%) children underwent endoscope-assisted craniosynostosis surgery and 32 (47%) patients underwent open repair. These studies all suggest that blood loss, transfusion rate, operating time, and length of hospital stay were superior for endoscopically treated children. Although potentially comparable or better cosmetic outcomes are reported, the paucity of evidence and considerable variability in outcomes preclude meaningful conclusions.

Conclusions: Limited data comparing open and endoscopic treatments for metopic, unilateral coronal, and lambdoid synostosis suggest a benefit for endoscopic techniques with respect to blood loss, transfusion, length of stay, and operating time. This report highlights shortcomings in evidence and gaps in knowledge regarding endoscopic repair of nonsagittal single-suture craniosynostosis, emphasizing the need for further matched-control studies.
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http://dx.doi.org/10.3171/2018.4.PEDS17730DOI Listing
October 2018

Development of synthetic simulators for endoscope-assisted repair of metopic and sagittal craniosynostosis.

J Neurosurg Pediatr 2018 08 1;22(2):128-136. Epub 2018 Jun 1.

1Center for Image-Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto.

OBJECTIVE Endoscope-assisted repair of craniosynostosis is a safe and efficacious alternative to open techniques. However, this procedure is challenging to learn, and there is significant variation in both its execution and outcomes. Surgical simulators may allow trainees to learn and practice this procedure prior to operating on an actual patient. The purpose of this study was to develop a realistic, relatively inexpensive simulator for endoscope-assisted repair of metopic and sagittal craniosynostosis and to evaluate the models' fidelity and teaching content. METHODS Two separate, 3D-printed, plastic powder-based replica skulls exhibiting metopic (age 1 month) and sagittal (age 2 months) craniosynostosis were developed. These models were made into consumable skull "cartridges" that insert into a reusable base resembling an infant's head. Each cartridge consists of a multilayer scalp (skin, subcutaneous fat, galea, and periosteum); cranial bones with accurate landmarks; and the dura mater. Data related to model construction, use, and cost were collected. Eleven novice surgeons (residents), 9 experienced surgeons (fellows), and 5 expert surgeons (attendings) performed a simulated metopic and sagittal craniosynostosis repair using a neuroendoscope, high-speed drill, rongeurs, lighted retractors, and suction/irrigation. All participants completed a 13-item questionnaire (using 5-point Likert scales) to rate the realism and utility of the models for teaching endoscope-assisted strip suturectomy. RESULTS The simulators are compact, robust, and relatively inexpensive. They can be rapidly reset for repeated use and contain a minimal amount of consumable material while providing a realistic simulation experience. More than 80% of participants agreed or strongly agreed that the models' anatomical features, including surface anatomy, subgaleal and subperiosteal tissue planes, anterior fontanelle, and epidural spaces, were realistic and contained appropriate detail. More than 90% of participants indicated that handling the endoscope and the instruments was realistic, and also that the steps required to perform the procedure were representative of the steps required in real life. CONCLUSIONS Both the metopic and sagittal craniosynostosis simulators were developed using low-cost methods and were successfully designed to be reusable. The simulators were found to realistically represent the surgical procedure and can be used to develop the technical skills required for performing an endoscope-assisted craniosynostosis repair.
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http://dx.doi.org/10.3171/2018.2.PEDS18121DOI Listing
August 2018

Advanced dynamic statistical parametric mapping with MEG in localizing epileptogenicity of the bottom of sulcus dysplasia.

Clin Neurophysiol 2018 06 30;129(6):1182-1191. Epub 2018 Mar 30.

Division of Neurology, The Hospital for Sick Children, Toronto, ON, Canada. Electronic address:

Objective: To investigate whether advanced dynamic statistical parametric mapping (AdSPM) using magnetoencephalography (MEG) can better localize focal cortical dysplasia at bottom of sulcus (FCDB).

Methods: We analyzed 15 children with diagnosis of FCDB in surgical specimen and 3 T MRI by using MEG. Using AdSPM, we analyzed a ±50 ms epoch relative to each single moving dipole (SMD) and applied summation technique to estimate the source activity. The most active area in AdSPM was defined as the location of AdSPM spike source. We compared spatial congruence between MRI-visible FCDB and (1) dipole cluster in SMD method; and (2) AdSPM spike source.

Results: AdSPM localized FCDB in 12 (80%) of 15 children whereas dipole cluster localized six (40%). AdSPM spike source was concordant within seizure onset zone in nine (82%) of 11 children with intracranial video EEG. Eleven children with resective surgery achieved seizure freedom with follow-up period of 1.9 ± 1.5 years. Ten (91%) of them had an AdSPM spike source in the resection area.

Conclusion: AdSPM can noninvasively and neurophysiologically localize epileptogenic FCDB, whether it overlaps with the dipole cluster or not.

Significance: This is the first study to localize epileptogenic FCDB using MEG.
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http://dx.doi.org/10.1016/j.clinph.2018.03.007DOI Listing
June 2018

Assessing Technical Performance and Determining the Learning Curve in Cleft Palate Surgery Using a High-Fidelity Cleft Palate Simulator.

Plast Reconstr Surg 2018 06;141(6):1485-1500

Toronto, Ontario, Canada.

Background: This study assessed technical performance in cleft palate repair using a newly developed assessment tool and high-fidelity cleft palate simulator through a longitudinal simulation training exercise.

Methods: Three residents performed five and one resident performed nine consecutive endoscopically recorded cleft palate repairs using a cleft palate simulator. Two fellows in pediatric plastic surgery and two expert cleft surgeons also performed recorded simulated repairs. The Cleft Palate Objective Structured Assessment of Technical Skill (CLOSATS) and end-product scales were developed to assess performance. Two blinded cleft surgeons assessed the recordings and the final repairs using the CLOSATS, end-product scale, and a previously developed global rating scale.

Results: The average procedure-specific (CLOSATS), global rating, and end-product scores increased logarithmically after each successive simulation session for the residents. Reliability of the CLOSATS (average item intraclass correlation coefficient (ICC), 0.85 ± 0.093) and global ratings (average item ICC, 0.91 ± 0.02) among the raters was high. Reliability of the end-product assessments was lower (average item ICC, 0.66 ± 0.15). Standard setting linear regression using an overall cutoff score of 7 of 10 corresponded to a pass score for the CLOSATS and the global score of 44 (maximum, 60) and 23 (maximum, 30), respectively. Using logarithmic best-fit curves, 6.3 simulation sessions are required to reach the minimum standard.

Conclusions: A high-fidelity cleft palate simulator has been developed that improves technical performance in cleft palate repair. The simulator and technical assessment scores can be used to determine performance before operating on patients.
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http://dx.doi.org/10.1097/PRS.0000000000004426DOI Listing
June 2018

Clinical Significance of Venous Anomalies in Syndromic Craniosynostosis.

Plast Reconstr Surg Glob Open 2018 Jan 18;6(1):e1613. Epub 2018 Jan 18.

Division of Plastic and Reconstructive Surgery, Department of Surgery, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada; and Division of Neurosurgery, Department of Surgery, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.

Background: The pattern of cranial venous drainage in syndromic craniosynostosis is unpredictable and not adequately understood. Collateral channels substitute for stenotic venous sinuses and pose potential risk for surgical intervention. The purpose of this study was to analyze the patterns of venous drainage in patients with syndromic craniosynostosis and their influence on operative planning and morbidity.

Methods: A retrospective study of patients with syndromic craniosynostosis from 2000 to 2013 was performed. Demographic data were collected including phenotype and associated pathologies. Pre- and/or postoperative venous imaging was reviewed for venous sinus stenosis, collateral emissaries, and persistent fetal sinuses. Categorization of anomalous venous drainage was performed, and the relationship with surgical morbidity was assessed.

Results: Forty-one patients were identified. Anomalies were present in 31 patients (76%) consisting of dural sinus stenosis in 28 (68%), dilated emissaries in 26 (63%), and fetal sinuses in 7 (17%). Pfeiffer syndrome was most commonly associated with anomalous drainage (100%). Venous anomalies were associated with elevated intracranial pressure (ICP), shunted hydrocephalus, Chiari malformations, and sleep apnea. In 5 cases, the surgical plan was adjusted based on anomalous anatomy. No mortalities occurred. Intraoperative complication rate was 7.3%, all with anomalous drainage. Median estimated blood loss was 1,100 cc for patients with anomalies versus 400 cc without anomalies ( = 0.181).

Conclusion: Cranial venous anomalies are commonly detected in patients with syndromic craniosynostosis and may affect surgical morbidity and outcome with a higher estimated blood loss, alteration of procedure, and postoperative morbidity. Detailed preoperative imaging of the venous drainage is therefore recommended in cases of syndromic synostosis.
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http://dx.doi.org/10.1097/GOX.0000000000001613DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5811287PMC
January 2018

Utility of additional dedicated high-resolution 3T MRI in children with medically refractory focal epilepsy.

Epilepsy Res 2018 07;143:113-119

Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada. Electronic address:

Purpose: In patients with medically refractory epilepsy and normal magnetic resonance imaging (MRI), high-resolution dedicated MRI may identify cryptic lesions. The aim of this study was to assess improvement in lesion detection and its impact on clinical management, using additional high-resolution dedicated 3T MRI in children with medically refractory epilepsy who had normal 3T epilepsy protocol MRI.

Materials And Methods: Children who had resective epilepsy surgery and suspected focal cortical dysplasia (FCD) or normal 3T epilepsy protocol MRI were included. Those with other diagnosis on MRI including tumor and hippocampal sclerosis were excluded. Patients who had normal MRI on 3T epilepsy protocol underwent dedicated high-resolution 3T MRI through the epileptogenic zone, guided by video EEG, Magnetoencephalography and FDG-PET data.

Results: 101 patients with at least 1 year follow-up were included. Twenty-nine of 44 (66%) patients who had normal epilepsy protocol MRI had a lesion identified on dedicated high-resolution MRI. The addition of dedicated high-resolution MRI to standard epilepsy protocol increased sensitivity from 53.1% (95%CI: 40%-66%) to 85.9% (95%CI: 75%-93%). Identified lesions were concordant to surgical resection in all patients and guided depth/strip electrode insertion in 20/25 (80%) patients who underwent staged resection. Dedicated MRI detected small deep seated lesions in 10/20 (50%), and guided depth electrodes placement, without which it would not be feasible, as the lobar location of epileptogenic zone from other non-invasive tests were not sufficiently precise.

Conclusion: Patients with non-lesional epilepsy on standard epilepsy protocol MR may benefit from high-resolution dedicated MRI to aid identification of an underlying lesion, which could impact surgical management and improve seizure control.
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http://dx.doi.org/10.1016/j.eplepsyres.2018.01.002DOI Listing
July 2018

Long-term visual outcomes of craniopharyngioma in children.

J Neurooncol 2018 May 17;137(3):645-651. Epub 2018 Jan 17.

Division of Neurosurgery, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.

Visual function is a critical factor in the diagnosis, monitoring, and prognosis of craniopharyngiomas in children. The aim of this study was to report the long-term visual outcomes in a cohort of pediatric patients with craniopharyngioma. The study design is a retrospective chart review of craniopharyngioma patients from a single tertiary-care pediatric hospital. 59 patients were included in the study. Mean age at presentation was 9.4 years old (range 0.7-18.0 years old). The most common presenting features were headache (76%), nausea/vomiting (32%), and vision loss (31%). Median follow-up was 5.2 years (range 1.0-17.2 years). During follow-up, visual decline occurred in 17 patients (29%). On Kaplan Meier survival analysis, 47% of the cases of visual decline occurred within 4 months of diagnosis, with the remaining cases occurring sporadically during follow-up (up to 8 years after diagnosis). In terms of risk factors, younger age at diagnosis, optic nerve edema at presentation, and tumor recurrence were found to have statistically significant associations with visual decline. At final follow-up, 58% of the patients had visual impairment in at least one eye but only 10% were legally blind in both eyes (visual acuity 20/200 or worse or < 20° of visual field). Vision loss is a common presenting symptom of craniopharyngiomas in children. After diagnosis, monitoring vision is important as about 30% of patients will experience significant visual decline. Long-term vision loss occurs in the majority of patients, but severe binocular visual impairment is uncommon.
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http://dx.doi.org/10.1007/s11060-018-2762-3DOI Listing
May 2018

Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate.

Epilepsia 2018 03 6;59(3):544-554. Epub 2018 Jan 6.

Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada.

Objective: Epileptic spasms (ES) often become drug-resistant. To reveal the electrophysiological difference between children with ES (ES+) and without ES (ES-), we compared the occurrence rate (OR) of high-frequency oscillations (HFOs) and the modulation index (MI) of coupling between slow and fast oscillations. In ES+, we hypothesized that (1) pathological HFOs are more widely distributed and (2) slow oscillations show stronger coupling with pathological HFOs than in ES-.

Methods: We retrospectively reviewed 24 children with drug-resistant multilobar onset epilepsy, who underwent intracranial video electroencephalography prior to multilobar resections. We measured the OR of HFOs and determined the electrodes with a high rate of HFOs by cluster analysis. We calculated MI, which reflects the degree of coupling between HFO (ripple/fast ripple [FR]) amplitude and 5 different frequency bands of delta and theta activities (0.5-1 Hz, 1-2 Hz, 2-3 Hz, 3-4 Hz, 4-8 Hz).

Results: In ES+ (n = 10), the OR , the number of electrodes with high-rate FRs, and the MI in all electrodes were significantly higher than in ES- (n = 14). In both the ES+ and ES- groups, MI was the highest among the 5 frequency bands. Within the good seizure outcome group, the OR and the MI in the resected area in ES+ were significantly higher than in ES- (OR , P = .04; MI , P = .04).

Significance: In ES+, the larger number of high-rate FR electrodes indicates more widespread epileptogenicity than in ES-. High values of OR and MI in ES+ compared to ES- are a signature of the severity of epileptogenicity. We proved that ES+ children who achieved seizure freedom following multilobar resections exhibited strong coupling between slow oscillations and FRs.
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http://dx.doi.org/10.1111/epi.13995DOI Listing
March 2018