Publications by authors named "Brian Hanak"

24 Publications

  • Page 1 of 1

Improving long-term outcomes in pediatric torcular dural sinus malformations with embolization and anticoagulation: a retrospective review of The Hospital for Sick Children experience.

J Neurosurg Pediatr 2021 Jul 30:1-7. Epub 2021 Jul 30.

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

Objective: Torcular dural sinus malformations (tDSMs) are rare pediatric cerebrovascular malformations characterized by giant venous lakes localized to the midline confluence of sinuses. Historical clinical outcomes of patients with these lesions were poor, though better prognoses have been reported in the more recent literature. Long-term outcomes in children with tDSMs are uncertain and require further characterization. The goal of this study was to review a cohort of tDSM patients with an emphasis on long-term outcomes and to describe the treatment strategy.

Methods: This study is a single-center retrospective review of a prospectively maintained data bank including patients referred to and cared for at The Hospital for Sick Children for tDSM from January 1996 to March 2019. Each patient's clinical, radiological, and demographic information, as well as their mother's demographic information, was collected for review.

Results: Ten patients with tDSM, with a mean follow-up of 58 months, were included in the study. Diagnoses were made antenatally in 8 patients, and among those cases, 4 families opted for either elective termination (n = 1) or no further care following delivery (n = 3). Of the 6 patients treated, 5 had a favorable long-term neurological outcome, and follow-up imaging demonstrated a decrease or stability in the size of the tDSM over time. Staged embolization was performed in 3 patients, and anticoagulation was utilized in 5 treated patients.

Conclusions: The authors add to a growing body of literature indicating that clinical outcomes in tDSM may not be as poor as initially perceived. Greater awareness of the lesion's natural history and pathophysiology, advancing endovascular techniques, and individualized anticoagulation regimens may lead to continued improvement in outcomes.
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http://dx.doi.org/10.3171/2021.3.PEDS20921DOI Listing
July 2021

Re-examining decompressive craniectomy medial margin distance from midline as a metric for calculating the risk of post-traumatic hydrocephalus.

J Clin Neurosci 2021 May 20;87:125-131. Epub 2021 Mar 20.

Department of Neurological Surgery, University of Washington, 325 Ninth Ave, Box 359924, Seattle, WA 98104, USA.

Decompressive craniectomy (DC) is a life-saving procedure in severe traumatic brain injury, but is associated with higher rates of post-traumatic hydrocephalus (PTH). The relationship between the medial craniectomy margin's proximity to midline and frequency of developing PTH is controversial. The primary study objective was to determine whether average medial craniectomy margin distance from midline was closer to midline in patients who developed PTH after DC for severe TBI compared to patients that did not. The secondary objective was to determine if a threshold distance from midline could be identified, at which the risk of developing PTH increased if the DC was performed closer to midline than this threshold. A retrospective review was performed of 380 patients undergoing DC at a single institution between March 2004 and November 2014. Clinical, operative and demographic variables were collected, including age, sex, DC parameters and occurrence of PTH. Statistical analysis compared mean axial craniectomy margin distance from midline in patients with versus without PTH. Distances from midline were tested as potential thresholds. No significant difference was identified in mean axial craniectomy margin distance from midline in patients developing PTH compared with patients with no PTH (n = 24, 12.8 mm versus n = 356, 16.6 mm respectively, p = 0.086). No significant cutoff distance from midline was identified (n = 212, p = 0.201). This study, the largest to date, was unable to identify a threshold with sufficient discrimination to support clinical recommendations in terms of DC margins with regard to midline, including thresholds reportedly significant in previously published research.
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http://dx.doi.org/10.1016/j.jocn.2021.02.025DOI Listing
May 2021

Computer-assisted surgery in medical and dental applications.

Expert Rev Med Devices 2021 Jul 6;18(7):669-696. Epub 2021 Jul 6.

Department of Periodontics, University of Washington School of Dentistry Seattle,98195 WA,USA.

Introduction: Computer-assisted surgery (CAS) is a broad surgical methodology that utilizes computer technology to both plan and execute surgical intervention. CAS is widespread in both medicine and dentistry as it allows for minimally invasive and precise surgical procedures. Key innovations in volumetric imaging, virtual surgical planning software, instrument tracking, and robotics have assisted in facilitating the transfer of surgical plans to precise execution of surgical procedures. CAS has long been used in certain medical specialties including neurosurgery, cardiology, orthopedic surgery, otolaryngology, and interventional radiology, and has since expanded to oral and maxillofacial application, particularly for computer-assisted implant surgery.

Areas Covered: This review provides an updated overview of the most current research for CAS in medicine and dentistry, with a focus on neurosurgery and dental implant surgery. The MEDLINE electronic database was searched and relevant original and review articles from 2005 to 2020 were included.

Expert Opinion: Recent literature suggests that CAS performs favorably in both neurosurgical and dental implant applications. Computer-guided surgical navigation is well entrenched as standard of care in neurosurgery. Whereas static computer-assisted implant surgery has become established in dentistry, dynamic computer-assisted navigation is newly poised to trend upward in dental implant surgery.
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http://dx.doi.org/10.1080/17434440.2021.1886075DOI Listing
July 2021

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

Oper Neurosurg (Hagerstown) 2021 01;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

Correction to: Postoperative isolated lower extremity supplementary motor area syndrome: case report and review of the literature.

Childs Nerv Syst 2020 Apr;36(4):877

Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.

The original version of this article unfortunately contained an error. The author apologizes for having provided an incorrect name: "Ali Moghadammjou" should be "Ali Moghaddamjou". Given in this article is the correct author name.
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http://dx.doi.org/10.1007/s00381-020-04504-xDOI Listing
April 2020

Klippel Feil Syndrome: Clinical Phenotypes Associated With Surgical Treatment.

Spine (Phila Pa 1976) 2020 Jun;45(11):718-726

Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.

Study Design: Retrospective study.

Objective: To define distinct Klippel-Feil syndrome (KFS) patient phenotypes that are associated with the need for surgical intervention.

Summary Of Background Data: KFS is characterized by the congenital fusion of cervical vertebrae; however, patients often present with a variety of other spinal and extraspinal anomalies suggesting this syndrome encompasses a heterogeneous patient population. Moreover, it remains unclear how the abnormalities seen in KFS correlate to neurological outcomes and the need for surgical intervention.

Methods: Principal component (PC) analysis was performed on 132 KFS patients treated at a large pediatric hospital between 1981 and 2018. Thirty-five variables pertaining to patient/disease-related factors were examined. Significant PCs were included as independent variables in multivariable logistic regression models designed to test associations with three primary outcomes: cervical spine surgery, thoracolumbar/sacral spine surgery, and cranial surgery.

Results: Fourteen significant PCs accounting for 70% of the variance were identified. Five components, representing four distinct phenotypes, were significantly associated with surgical intervention. The first group consisted of predominantly subaxial cervical spine fusions, thoracic spine abnormalities and was associated with thoracolumbar/sacral spine surgery. The second group was largely represented by axial cervical spine anomalies and had high association with cervical subluxation and cervical spine surgery. A third group, heavily represented by Chiari malformation, was associated with cranial surgery. Lastly, a fourth group was defined by thoracic vertebral anomalies and associations with sacral agenesis and scoliosis. This phenotype was associated with thoracolumbar/sacral spine surgery.

Conclusion: This is the first data-driven analysis designed to relate KFS patient phenotypes to surgical intervention and provides important insight that may inform targeted follow-up regimens and surgical decision-making.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003368DOI Listing
June 2020

Postoperative isolated lower extremity supplementary motor area syndrome: case report and review of the literature.

Childs Nerv Syst 2020 01 9;36(1):189-195. Epub 2019 Nov 9.

Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.

The supplementary motor area (SMA) syndrome is characterized by transient weakness and akinesia contralateral to the side of the affected hemisphere. The underlying pathology of the syndrome is not fully understood but is thought to be related to lesions in the SMA, residing principally in the mesial superior frontal gyrus (Broadmann's area 6c). Although the SMA syndrome a well-characterized clinical entity, we report herein, to our knowledge, the first case of isolated lower extremity SMA syndrome in the literature. This case highlights the importance of considering this rare clinical entity in the context of new or worsening postoperative neurologic deficits. Moreover, early studies did not support somatotopic organization of the SMA as in the primary motor cortex; emerging evidence suggests that delicate somatotopic representation may underlie distinct presentations like that reported in the present case.
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http://dx.doi.org/10.1007/s00381-019-04362-2DOI Listing
January 2020

Rapid Intraoperative in Situ Synthetic Cranioplasty.

World Neurosurg 2018 Apr 31;112:161-165. Epub 2018 Jan 31.

Department of Neurological Surgery, University of Washington, Seattle, Washington, USA. Electronic address:

Craniectomy is a frequently performed neurosurgical procedure, and coverage of the cranial defect is necessary for protection of the underlying brain, cosmesis, and patient satisfaction. We report a new technique for intraoperative in situ synthetic cranioplasty that provides one-step resection of skull osteomas and reconstruction of cranial defects. Strategies of intraoperative cranioplasty are reviewed. A 48-year-old man who presented with a suspected benign osteoma over his forehead was offered surgical excision and primary cranioplasty in a one-step procedure using hydroxyapatite bone cement, a dural prosthetic, and a resorbable plate. Following craniectomy around the lesion, there was evidence of dural and bone involvement. The craniectomy was enlarged, and the involved dura was resected. SYNTHECEL dura repair was used to repair the dural defect and at the same time fashioned to form a receptacle for the cranioplasty by fixation of the dural substrate to the cut vertical bone edges. DirectInject hydroxyapatite bone cement was used to fill the receptacle and contoured to the curvature of the adjacent skull. A Delta resorbable plate was then placed over the bone cement and fixed to the skull. This technique provided a satisfactory cosmetic outcome following craniectomy for benign skull tumor excision. When possible, one-step surgery with primary cranioplasty should be considered.
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http://dx.doi.org/10.1016/j.wneu.2018.01.126DOI Listing
April 2018

Post-Traumatic Hydrocephalus in Children: A Retrospective Study in 42 Pediatric Hospitals Using the Pediatric Health Information System.

Neurosurgery 2018 10;83(4):732-739

Harborview Injury Prevention Research Center, Harborview Medical Center, Seattle, Washington.

Background: Post-traumatic hydrocephalus (PTH) is a potentially treatable cause of poor recovery from traumatic brain injury (TBI) that remains poorly understood, particularly among children.

Objective: To better understand the risk factors for pediatric PTH using a large, multi-institutional database.

Methods: We conducted a retrospective cohort study using administrative data from 42 pediatric hospitals participating in the Pediatric Health Information System. All patients ≤21 yr surviving a hospitalization with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code for TBI were identified. The primary outcome was PTH, defined by an ICD-9-CM procedure code for surgical management of hydrocephalus within 6 mo. Data were analyzed using multivariable logistic regression.

Results: We identified 91 583 patients ≤21 yr with TBI, 846 of whom developed PTH. Odds of PTH were significantly higher in children <1 yr compared to older age groups. A total of 48.7% of PTH cases were victims of abuse (adjusted odds ratio [aOR] 2.62, 95% confidence interval [CI] 2.16-3.18). PTH was more common after craniotomy (aOR 1.60, 95% CI 1.30-1.97). Craniectomy without early cranioplasty was associated with markedly increased odds of PTH (aOR 3.67, 95% CI 2.66-5.07), an effect not seen in those undergoing cranioplasty within 30 d (aOR 1.19, 95% CI 0.75-1.89).

Conclusion: PTH was seen in 0.9% of children who sustained a TBI and was more common in those <1 yr. Severe injury, abuse, and craniectomy with delayed cranioplasty were associated with greatly increased likelihood of PTH. Early cranioplasty in children who require craniectomy may reduce the risk for PTH.
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http://dx.doi.org/10.1093/neuros/nyx470DOI Listing
October 2018

A Single-Institution Experience with Pineal Region Tumors: 50 Tumors Over 1 Decade.

Oper Neurosurg (Hagerstown) 2017 10;13(5):566-575

Department of Neurological Surgery, University of Washington, Seattle, Washington.

Background: Pineal region tumors are rare intracranial tumors that are more common in children than adults. Surgical management of tumors in this region using a tailored approach is a strategy that enhances extent of resection and neurological outcome.

Objective: To review our institutional experience with pineal region tumors in children and adults over the past 10 years.

Methods: Our institutional pathology database and patient records were retrospectively reviewed for details regarding clinical and radiological presentation, surgical management, extent of resection, morbidity, and neurological outcome. Statistical analysis was performed to assess for variables related to functional outcomes.

Results: Fifty patients were identified as having undergone surgical management of a pineal region tumor with at least 1 year of follow-up. Forty-one percent presented with a Karnofsky Performance Scale (KPS) score of 70 or less, all of whom had concomitant hydrocephalus that required urgent treatment. The following variables were statistically significant to KPS score on admission: age, tumor volume, preoperative hydrocephalus, length of hospitalization (total and intensive care unit), and elevations in serum tumor markers. The median postoperative (2 months) KPS score was 90. The following variables were statistically significant with respect to change in KPS score postoperatively: tumor maximum diameter, KPS score on admission, and intensive care unit length of stay. The specific surgical strategy did not correlate to extent of tumor resection, morbidity, immediate neurological outcome, and progression-free survival.

Conclusion: Extent of resection, neurological outcome, and progression-free survival in the patients in our series were not related to the specific surgical approach employed and its perioperative complications.
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http://dx.doi.org/10.1093/ons/opx038DOI Listing
October 2017

Reduced cell attachment to poly(2-hydroxyethyl methacrylate)-coated ventricular catheters in vitro.

J Biomed Mater Res B Appl Biomater 2018 04 20;106(3):1268-1279. Epub 2017 Jun 20.

Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.

The majority of patients with hydrocephalus are dependent on ventriculoperitoneal shunts for diversion of excess cerebrospinal fluid. Unfortunately, these shunts are failure-prone and over half of all life-threatening pediatric failures are caused by obstruction of the ventricular catheter by the brain's resident immune cells, reactive microglia and astrocytes. Poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels are widely used for biomedical implants. The extreme hydrophilicity of PHEMA confers resistance to protein fouling, making it a strong candidate coating for ventricular catheters. With the advent of initiated chemical vapor deposition (iCVD), a solvent-free coating technology that creates a polymer in thin film form on a substrate surface by introducing gaseous reactant species into a vacuum reactor, it is now possible to apply uniform polymer coatings on complex three-dimensional substrate surfaces. iCVD was utilized to coat commercially available ventricular catheters with PHEMA. The chemical structure was confirmed on catheter surfaces using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. PHEMA coating morphology was characterized by scanning electron microscopy. Testing PHEMA-coated catheters against uncoated clinical-grade catheters in an in vitro hydrocephalus catheter bioreactor containing co-cultured astrocytes and microglia revealed significant reductions in cell attachment to PHEMA-coated catheters at both 17-day and 6-week time points. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1268-1279, 2018.
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http://dx.doi.org/10.1002/jbm.b.33915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738300PMC
April 2018

Cerebrospinal Fluid Shunting Complications in Children.

Pediatr Neurosurg 2017 2;52(6):381-400. Epub 2017 Mar 2.

Department of Neurological Surgery, University of Washington and Seattle Children's Hospital, Seattle, WA, USA.

Although cerebrospinal fluid (CSF) shunt placement is the most common procedure performed by pediatric neurosurgeons, shunts remain among the most failure-prone life-sustaining medical devices implanted in modern medical practice. This article provides an overview of the mechanisms of CSF shunt failure for the 3 most commonly employed definitive CSF shunts in the practice of pediatric neurosurgery: ventriculoperitoneal, ventriculopleural, and ventriculoatrial. The text has been partitioned into the broad modes of shunt failure: obstruction, infection, mechanical shunt failure, overdrainage, and distal catheter site-specific failures. Clinical management strategies for the various modes of shunt failure are discussed as are research efforts directed towards reducing shunt complication rates. As it is unlikely that CSF shunting will become an obsolete procedure in the foreseeable future, it is incumbent on the pediatric neurosurgery community to maintain focused efforts to improve our understanding of and management strategies for shunt failure and shunt-related morbidity.
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http://dx.doi.org/10.1159/000452840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915307PMC
August 2018

An algorithmic approach to the management of unrecognized hydrocephalus in pediatric candidates for intrathecal baclofen pump implantation.

Surg Neurol Int 2016 20;7:105. Epub 2016 Dec 20.

Department of Neurosurgery, Seattle Children's Hospital, Seattle, Washington, USA.

Background: Complications of intrathecal baclofen (ITB) pump implantation for treatment of pediatric patients with spasticity and dystonia associated with cerebral palsy remain unacceptably high. To address the concern that some patients may have underlying arrested hydrocephalus, which is difficult to detect clinically because of a low baseline level of neurological function, and may contribute to the high rates of postoperative cerebrospinal fluid leak, wound breakdown, and infection associated with ITB pump implantation, the authors implemented a standardized protocol including mandatory cranial imaging and assessment of intracranial pressure (ICP) by lumbar puncture prior to ITB pump implantation.

Methods: A retrospective case series of patients considered for ITB pump implantation between September 2012 and October 2014 at Seattle Children's Hospital is presented. All patients underwent lumbar puncture under general anesthesia prior to ITB pump implantation and, if the opening pressure was greater than 21 cmHO, ITB pump implantation was aborted and alternative management options were presented to the patient's family.

Results: Eighteen patients were treated during the study time period. Eight patients (44.4%) who had ICPs in excess of 21 cmHO on initial LP were identified. Eleven patients (61.1%) ultimately underwent ITB pump implantation (9/10 in the "normal ICP" group and 2/8 in the "elevated ICP" group following ventriculoperitoneal shunt placement), without any postoperative complications.

Conclusions: Given the potentially high rate of elevated ICP and arrested hydrocephalus, the authors advocate pre-implantation assessment of ICP under controlled conditions and a thoughtful consideration of the neurosurgical management options for patients with elevated ICP.
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http://dx.doi.org/10.4103/2152-7806.196236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5223398PMC
December 2016

Toward a better understanding of the cellular basis for cerebrospinal fluid shunt obstruction: report on the construction of a bank of explanted hydrocephalus devices.

J Neurosurg Pediatr 2016 Aug 1;18(2):213-23. Epub 2016 Apr 1.

Center for Integrative Brain Research, Seattle Children's Research Institute;

OBJECTIVE Shunt obstruction by cells and/or tissue is the most common cause of shunt failure. Ventricular catheter obstruction alone accounts for more than 50% of shunt failures in pediatric patients. The authors sought to systematically collect explanted ventricular catheters from the Seattle Children's Hospital with a focus on elucidating the cellular mechanisms underlying obstruction. METHODS In the operating room, explanted hardware was placed in 4% paraformaldehyde. Weekly, samples were transferred to buffer solution and stored at 4°C. After consent was obtained for their use, catheters were labeled using cell-specific markers for astrocytes (glial fibrillary acidic protein), microglia (ionized calcium-binding adapter molecule 1), and choroid plexus (transthyretin) in conjunction with a nuclear stain (Hoechst). Catheters were mounted in custom polycarbonate imaging chambers. Three-dimensional, multispectral, spinning-disk confocal microscopy was used to image catheter cerebrospinal fluid-intake holes (10× objective, 499.2-μm-thick z-stack, 2.4-μm step size, Olympus IX81 inverted microscope with motorized stage and charge-coupled device camera). Values are reported as the mean ± standard error of the mean and were compared using a 2-tailed Mann-Whitney U-test. Significance was defined at p < 0.05. RESULTS Thirty-six ventricular catheters have been imaged to date, resulting in the following observations: 1) Astrocytes and microglia are the dominant cell types bound directly to catheter surfaces; 2) cellular binding to catheters is ubiquitous even if no grossly visible tissue is apparent; and 3) immunohistochemical techniques are of limited utility when a catheter has been exposed to Bugbee wire electrocautery. Statistical analysis of 24 catheters was performed, after excluding 7 catheters exposed to Bugbee wire cautery, 3 that were poorly fixed, and 2 that demonstrated pronounced autofluorescence. This analysis revealed that catheters with a microglia-dominant cellular response tended to be implanted for shorter durations (24.7 ± 6.7 days) than those with an astrocyte-dominant response (1183 ± 642 days; p = 0.027). CONCLUSIONS Ventricular catheter occlusion remains a significant source of shunt morbidity in the pediatric population, and given their ability to intimately associate with catheter surfaces, astrocytes and microglia appear to be critical to this pathophysiology. Microglia tend to be the dominant cell type on catheters implanted for less than 2 months, while astrocytes tend to be the most prevalent cell type on catheters implanted for longer time courses and are noted to serve as an interface for the secondary attachment of ependymal cells and choroid plexus.
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http://dx.doi.org/10.3171/2016.2.PEDS15531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915300PMC
August 2016

Fabrication of three-dimensional hydrogel scaffolds for modeling shunt failure by tissue obstruction in hydrocephalus.

Fluids Barriers CNS 2015 Nov 14;12:26. Epub 2015 Nov 14.

Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA.

Background: Shunt obstruction in the treatment of hydrocephalus is poorly understood, is multi-factorial, and in many cases is modeled ineffectively. Several mechanisms may be responsible, one of which involves shunt infiltration by reactive cells from the brain parenchyma. This has not been modeled in culture and cannot be consistently examined in vivo without a large sample size.

Methods: We have developed and tested a three-dimensional in vitro model of astrocyte migration and proliferation around clinical grade ventricular catheters and into catheter holes that mimics the development of cellular outgrowth from the parenchyma that may contribute to shunt obstruction.

Results: Cell attachment and growth was observed on shunt catheters for as long as 80 days with at least 77% viability until 51 days. The model can be used to study cellular attachment to ventricular catheters under both static and pulsatile flow conditions, which better mimic physiological cerebrospinal fluid dynamics and shunt system flow rates (0.25 mL/min, 100 pulses/min). Pulsatile flow through the ventricular catheter decreased cell attachment/growth by 63% after 18 h. Under both conditions it was possible to observe cells accumulating around and in shunt catheter holes.

Conclusions: Alone or in combination with previously-published culture models of shunt obstruction, this model serves as a relevant test bed to analyze mechanisms of shunt failure and to test catheter modifications that will prevent cell attachment and growth.
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http://dx.doi.org/10.1186/s12987-015-0023-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4650346PMC
November 2015

Preoperative embolization of intracranial hemangiopericytomas: case series and introduction of the transtumoral embolization technique.

J Neurointerv Surg 2016 Oct 16;8(10):1084-94. Epub 2015 Oct 16.

Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA.

Background And Purpose: Hemangiopericytomas (HPCs) are rare dural-based neoplasms. Preoperative embolization of these notoriously hypervascular tumors can be challenging as they often receive their dominant blood supply from pial feeders arising from the internal carotid artery (ICA) or vertebrobasilar (VB) circulation. This study reviews our historical experience with HPC embolization and introduces the transtumoral technique for backfilling pial tumor vasculature by delivering Onyx-18 through diminutive external carotid artery (ECA) feeders.

Methods: A retrospective review of all preoperative HPC embolizations performed at Anonymous University #1 (September 2002-November 2014) and Anonymous University #2 (January 2014-November 2014) is presented.

Results: Fifteen patients with pathologically confirmed HPC underwent 17 embolizations. More extensive devascularization percentages were achieved for HPCs with primarily ECA blood supply (76.4±10.7%; n=6) than with HPCs supplied via the ICA/VB circulation (57.9±26.9%; n=8; p=0.046). There was a trend towards greater devascularization of ICA/VB-dominant HPCs embolized with Onyx (70.0±34.6%; n=4) versus polyvinyl alcohol particles (33.3±15.3%; n=3). The extent of angiographic devascularization negatively correlated with intraoperative blood loss (rho=-0.71; p=0.005). There were no embolization-related complications.

Conclusions: The extent of preoperative embolization of HPCs correlates with decreased intraoperative blood loss. However, HPCs with an ICA/VB-dominant blood supply remain challenging embolization targets, demonstrating reduced devascularization percentages compared with ECA-dominant counterparts. The authors favor the use of Onyx for ICA/VB-dominant HPCs, noting a trend towards an improved devascularization rate.
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http://dx.doi.org/10.1136/neurintsurg-2015-011980DOI Listing
October 2016

Are aneurysms treated with balloon-assisted coiling and stent-assisted coiling different? Morphological analysis of 113 unruptured wide-necked aneurysms treated with adjunctive devices.

Neurosurgery 2014 Aug;75(2):145-51; quiz 151

*Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida; ‡Department of Neurological Surgery, University of Washington School of Medicine, Harborview Medical Center, Seattle, Washington.

Background: In the endovascular treatment of wide-necked unruptured aneurysms, there is controversy over which adjunctive device (stent vs balloon) is appropriate. At the payer level it has been posited that stents and balloons treat the same aneurysms, and, as such, the more expensive stents should not be reimbursed.

Objective: We challenge this assertion, and instead hypothesize that aneurysms treated with stent assistance are morphologically different than those selected for balloon assistance.

Methods: Retrospective review of unruptured aneurysms treated with an adjunctive device between 2008 and 2010. Morphological analysis was performed on the pretreatment 2-D catheter angiogram. The immediate posttreatment Raymond score was compared with that seen on the 12-month follow-up angiogram.

Results: One hundred six unruptured aneurysms were treated with an adjunctive device and followed for a mean of 24.5 months. Morphological analysis revealed a lower dome-to-neck ratio (1.5 vs 1.2) and aspect ratio (1.44 vs 1.16) in the aneurysms treated with stent assistance vs balloon assistance. Of the 15.3% that were worse on follow-up angiography, there was no statistical difference between those treated with a stent vs a balloon (17.1% vs 14.2%). The overall re-treatment rate was 10.2% and was not statistically different between the 2 groups (12.7% vs 5.7%).

Conclusion: We found that unruptured aneurysms selected for treatment with stent-assisted coiling are morphologically different from those selected for treatment with balloon assistance. Despite the more challenging morphology, Raymond scores and re-treatment rates at 1 year were not statistically different between the 2 groups, suggesting an important role for stents in the treatment of unruptured aneurysms.
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http://dx.doi.org/10.1227/NEU.0000000000000366DOI Listing
August 2014

Blunt traumatic occlusion of the internal carotid and vertebral arteries.

J Neurosurg 2014 Jun 28;120(6):1446-50. Epub 2014 Mar 28.

Departments of Neurological Surgery and.

Object: The stroke rate, management, and outcome after blunt cerebrovascular occlusion (Biffl Grade IV injury) is not well defined, given the rarity of the disease. Both hemodynamic failure and embolic mechanisms have been implicated in the pathophysiology of subsequent stroke after blunt cerebrovascular occlusion. In this study, the authors evaluated their center's experience with Biffl Grade IV injuries, focusing on elucidating the mechanisms of stroke and their optimal management.

Methods: A retrospective review identified all internal carotid artery (ICA) or vertebral artery (VA) Biffl Grade IV injuries over a 7-year period at a single institution.

Results: Fifty-nine Biffl Grade IV injuries were diagnosed affecting 11 ICAs, 44 unilateral VAs, and 2 bilateral VAs. The stroke rates were 64%, 9%, and 50%, respectively. Of the 11 Biffl Grade IV ICA injuries, 5 presented with stroke while 2 developed delayed stroke. An ipsilateral posterior communicating artery greater than 1 mm on CT angiography was protective against stroke due to hemodynamic failure (p = 0.015). All patients with Biffl Grade IV injuries affecting the ICA who had at least 8 emboli per hour on transcranial Doppler (TCD) ultrasonography developed an embolic pattern of stroke (p = 0.006). Treatment with aspirin versus dual antiplatelet therapy had a similar effect on stroke rate in the ICA group (p = 0.5) and all patients who suffered stroke either died (n = 3) or required a decompressive hemicraniectomy with subsequent poor outcome (n = 4). All 10 strokes associated with Biffl Grade IV VA injuries were embolic and clinically asymptomatic. In VA Biffl Grade IV injury, neither the presence of emboli nor treatment with antiplatelet agents affected stroke rates.

Conclusions: At the authors' institution, traumatic ICA occlusion is rare but associated with a high stroke rate. Robust collateral circulation may mitigate its severity. Embolic monitoring with TCD ultrasonography and prophylactic antiplatelet therapy should be used in all ICA Biffl Grade IV injuries. Unilateral VA Biffl Grade IV injury is the most common type of traumatic occlusion and is associated with significantly less morbidity. Embolic monitoring using TCD and prophylactic antiplatelet therapy do not appear to be beneficial in patients with traumatic VA occlusion.
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http://dx.doi.org/10.3171/2014.2.JNS131658DOI Listing
June 2014

Postoperative intensive care unit requirements after elective craniotomy.

World Neurosurg 2014 Jan 24;81(1):165-72. Epub 2012 Nov 24.

Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Objective: Commonly, patients undergoing craniotomy are admitted to an intensive care setting postoperatively to allow for close monitoring. We aim to determine the frequency with which patients who have undergone elective craniotomies require intensive care unit (ICU)-level interventions or experience significant complications during the postoperative period to identify a subset of patients for whom an alternative to ICU-level care may be appropriate.

Methods: Following Institutional Review Board approval, a prospective, consecutive cohort of adult patients undergoing elective craniotomy was established at the Massachusetts General Hospital between the dates of April 2010 and March 2011. Inclusion criteria were intradural operations requiring craniotomy performed on adults (18 years of age or older). Exclusion criteria were cases of an urgent or emergent nature, patients who remained intubated postoperatively, and patients who had a ventriculostomy drain in place at the conclusion of the case.

Results: Four hundred patients were analyzed. Univariate analysis revealed that patients with diabetes (P = 0.00047), those who required intraoperative blood product administration (P = 0.032), older patients (P < 0.0001), those with higher intraoperative blood losses (P = 0.041), and those who underwent longer surgical procedures (P = 0.021) were more likely to require ICU-level interventions or experience significant postoperative complications. Multivariate analysis only found diabetes (P = 0.0005) and age (P = 0.0091) to be predictive of a patient's need for postoperative ICU admission.

Conclusions: Diabetes and older age predict the need for ICU-level intervention after elective craniotomy. Properly selected patients may not require postcraniotomy ICU monitoring. Further study of resource utilization is necessary to validate these preliminary findings, particularly in different hospital types.
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http://dx.doi.org/10.1016/j.wneu.2012.11.068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3596491PMC
January 2014

Cerebral aneurysms with intrasellar extension: a systematic review of clinical, anatomical, and treatment characteristics.

J Neurosurg 2012 Jan 4;116(1):164-78. Epub 2011 Nov 4.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Object: Intrasellar aneurysms are rare lesions that often mimic pituitary tumors, potentially resulting in catastrophic outcomes if they are not appropriately recognized. The authors aimed to characterize the clinical and anatomical details of this poorly defined entity in the modern era of neuroimaging and open/endovascular neurosurgery.

Methods: A PubMed literature review was conducted to identify all studies reporting noniatrogenic aneurysms with intrasellar extension, as confirmed by CT or MR imaging and angiography. Clinical, anatomical, and treatment characteristics were analyzed.

Results: Thirty-one studies reporting 40 cases of intrasellar aneurysms were identified. Six patients (15%) presented with aneurysmal rupture. Patients with unruptured aneurysms presented with the following signs and symptoms: headache (61%), visual field cuts/decreased visual acuity (61%), endocrinopathy (57%), symptomatic hyponatremia (21%), and cranial nerve paresis (other than optic nerve) (18%). The most common endocrine abnormalities were hyperprolactinemia and hypogonadism. Eight aneurysms (20%) were diagnosed in conjunction with a pituitary adenoma. Aneurysms could be categorized into 2 primary anatomical groups as follows: 1) cavernous/clinoid segment internal carotid artery (ICA) (infradiaphragmatic) aneurysms with medial extension into the sella; and 2) suprasellar (supradiaphragmatic) aneurysms originating from the ophthalmic segment of the ICA or from the anterior communicating artery, with inferomedial extension into the sella. The mean diameters of infradiaphragmatic and supradiaphragmatic aneurysms were 14.5 and 21.8 mm, respectively. Infradiaphragmatic aneurysms were much more likely to present with endocrinopathy, whereas supradiaphragmatic ones presented more commonly with visual disturbances. Aneurysms with infradiaphragmatic growth were generally treated using either endovascular techniques or surgical trapping and bypass, while supradiaphragmatic aneurysms were more often treated by surgical clipping.

Conclusions: Aneurysms with intrasellar extension typically present due to mass effect on surrounding structures, and they can be classified as infradiaphragmatic cavernous or clinoid segment ICA aneurysms, or supradiaphragmatic ophthalmic ICA or anterior communicating artery aneurysms. Varying approaches exist for treating these complex aneurysms, and intervention strategies depend substantially on the anatomical subtype.
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http://dx.doi.org/10.3171/2011.9.JNS11380DOI Listing
January 2012

Fourth ventricular neurocystercercosis presenting with acute hydrocephalus.

J Clin Neurosci 2011 Jun 19;18(6):867-9. Epub 2011 Apr 19.

Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02115, USA.

Neurocysticercosis is an infection caused by the larvae of the pork tapeworm Taenia solium. Parenchymal lesions commonly present with seizure activity and intraventricular lesions can cause hydrocephalus. A 33-year-old female patient presented in a comatose state with acute hydrocephalus and a fourth ventricle lesion. She underwent placement of an external ventricular drain. Resection of the fourth ventricle lesion through a suboccipital approach allowed for restoration of normal cerebrospinal fluid (CSF) flow and relief of midbrain compression. The lesion was resected intact and the patient returned to normal neurological function. No CSF diversion procedure was necessary. The patient was discharged on cysticidal and steroid therapy. We concluded that surgical resection of lesions in the fourth ventricle attributed to neurocysticercosis is appropriate when brainstem compression is prominent. Resection may also avoid the need for permanent CSF diversion. We also reviewed the evidence-based management strategies described in the literature.
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http://dx.doi.org/10.1016/j.jocn.2010.12.002DOI Listing
June 2011

Trends in inpatient setting laminectomy for excision of herniated intervertebral disc: Population-based estimates from the US nationwide inpatient sample.

Surg Neurol Int 2011 Jan 24;2. Epub 2011 Jan 24.

Department of Neurological Surgery, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA.

Background: Herniated intervertebral discs can result in pain and neurological compromise. Treatment for this condition is categorized as surgical or non-surgical. We sought to identify trends in inpatient surgical management of herniated intervertebral discs using a national database.

Methods: Patient discharges identified with a principal procedure relating to laminectomy for excision of herniated intervertebral disc were selected from the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project - Agency for Healthcare Research and Quality, Rockville, MD), under the auspices of a data user agreement. These surgical patients did not undergo instrumented fusion. To account for the Nationwide Inpatient Sample weighting schema, design-adjusted analyses were used. The estimates of standard errors were calculated using SUDAAN software (Research Triangle International, NC, USA). This software is based on the International Classification of Diseases, 9(th) Revision, Clinical Modification (ICD-9-CM); a uniform and standardized coding system.

Results: Using International Classification of Disease 9(th) Revision clinical modifier (ICD-9 CM) procedure code 80.51, we were able to identify disc excision, in part or whole, by laminotomy or hemilaminectomy. The incidence of laminectomy for the excision of herniated intervertebral disc has decreased dramatically from 1993 where 266,152 cases were reported [CI = 22,342]. In 2007, only 123,398 cases were identified [CI = 12,438]. The average length of stay in 1993 was 4 days [CI = 0.17], and in 2007 it decreased to just 2 days [CI = 0.17]. Both these comparisons were significantly different at P < 0.001. The average inflation adjusted (2007 buying power) charge of the procedure in 1993 was 14,790.87 USD [CI = 916.85]. This value rose in 2007 to 24,639 USD [CI = 1,485.51]. This difference was significant at P < 0.001.

Conclusions: National estimates indicate that the incidence of inpatient laminectomy for the excision of herniated intervertebral disc has decreased significantly. This trend is multifactorial and is likely related to developments in outcomes research, the growing popularity of alternative procedures (intervertebral instrumented fusion), and transition to an ambulatory setting of surgical care.
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http://dx.doi.org/10.4103/2152-7806.76144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3031049PMC
January 2011

Changing trends in the epidemiology of pediatric lead exposure: interrelationship of blood lead and ZPP concentrations and a comparison to the US population.

Ther Drug Monit 2003 Aug;25(4):415-20

Soldin Research and Consultants, Inc., Bethesda, Maryland 20816, USA.

Objectives: To determine blood lead and zinc protoporphyrin (ZPP) concentrations in a pediatric population, confirm their interrelationship at low blood lead concentrations, and assess changing trends through comparison of these data with those found in a similar population 10 years earlier and to US national values.

Study Design And Methods: The study was conducted in a large pediatric hospital in the Washington DC area (CNMC) on patient whole blood specimens (n = 4908) (0-17 years) accrued from January 2001 to June 2002. Pediatric blood lead concentrations were determined by atomic absorption spectrophotometry, and ZPP by hematofluorometry. The data were analyzed using a computer adaptation of the Hoffmann approach.

Results And Conclusions: Blood lead level (BLL) means ranged between 2.2 and 3.3 micro g/dL, and the median BLL was 3 micro g/dL throughout. Mean ZPP concentrations ranged between 21.1 and 26.6 micro g/dL and the median concentrations between 21 and 27 micro g/dL. In comparison to data obtained from a similar pediatric population at CNMC between 1991 and 1992, pediatric BLLs have significantly declined in the Washington DC area. The current data are also compared with data obtained from the National Health and Nutrition Examination Survey (NHANES III) of the US population. The interrelationship between ZPP and BLLs is examined.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3635530PMC
http://dx.doi.org/10.1097/00007691-200308000-00001DOI Listing
August 2003

Blood lead concentrations in children: new ranges.

Clin Chim Acta 2003 Jan;327(1-2):109-13

Soldin Research and Consultants, Inc, Bethesda, MD 20816, USA.

Background: Lead exposure in young children may have adverse neurodevelopmental effects. Currently, an increased blood lead concentration is defined as >or=10 microg/dl for males and females of all ages, including children younger than 6 years. Using a large hospital population (n=11145), we define more specific ranges for pediatric blood lead concentrations.

Methods: Pediatric blood lead concentrations were determined (atomic absorption spectrophotometry) on patient samples accrued from January 2001 to June 2002, and the data was analyzed employing the Hoffman approach.

Results: For lead, the 2.5th and 97.5th percentiles for subjects aged 0 to 12 months were 2.3 to 4.7 microg/dl for females and 1.8 to 4.9 microg/dl for males. The 97.5th percentiles increased for the 1-2 years age group both for females (5.2 microg/dl) and males (5.6 microg/dl). There was a significant decrease in blood lead concentrations after age 10 years, the 97.5th percentile being 4.4 microg/dl in both female and male subjects. The values in all corresponding age groups were similar for females and for males. The medians of all age groups were similar for females and for male subjects.

Conclusion: The blood lead concentrations are much lower compared to previously published data.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3635836PMC
http://dx.doi.org/10.1016/s0009-8981(02)00333-9DOI Listing
January 2003
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