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Dive into the research topics where Marlise P. dos Santos is active.

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Featured researches published by Marlise P. dos Santos.


Journal of NeuroInterventional Surgery | 2012

Outcome in small aneurysms (<4 mm) treated by endovascular coiling

Cheemun Lum; Surendra Babu Narayanam; Leonardo Silva; Jai Jai Shiva Shankar; Miguel Bussiere; Marlise P. dos Santos; Howard Lesiuk

Background Coiling of small aneurysms can be technically challenging. These aspects of coiling tend to be less problematic in medium to large aneurysms as they are more accommodating of microcatheters and coils. When physicians are asked their opinion regarding aneurysm coilability in small aneurysms, the decision often lies in the operators feeling that they could reasonably exclude the aneurysm with a complication rate similar to larger aneurysms. The purpose of our study was to investigate the feasibility, intraprocedural rupture rates and long term durability of endovascular coiling for small (≤4 mm) aneurysms compared with non-small (>4 mm) aneurysms. To control for factors such as vessel tortuosity and aneurysm location, a control group was chosen matched to the study group both in age and aneurysm location. Materials and methods A retrospective review of 360 intracranial aneurysms coiled at our institution between 2003 and 2008 was performed. For the control group, intracranial aneurysms coiled in the same period matched to location and age were chosen. Results The frequency of intraprocedural perforations was 4/34 (0.12) and 3/68 (0.04) for the small and non-small cohort, respectively (p=0.22). All patients who had a perforation in the small aneurysm groups had a good clinical outcome compared with 1/3 in the non-small group (two mortalities). The frequency of recanalization for the small and non-small groups was 3/34 (0.09) and 23/68 (0.33), respectively (p=0.006). There was no retreatments in the small aneurysm group and five (0.07) in the non-small group (p=0.116). Conclusion Coiling of small (≤4 mm) aneurysms is feasible with a reasonable complication rate. There is a non-significant increase in frequency of intraprocedural rupture with coiling of small aneurysms compared with controls matched to aneurysm location and age but this is not associated with increased morbidity. Coiling of small aneurysms leads to durable results at long term follow-up.


Journal of NeuroInterventional Surgery | 2013

Heparin dosing is associated with diffusion weighted imaging lesion load following aneurysm coiling

Mary Jane Lim Fat; Mohammed Al-Hazzaa; Miguel Bussière; Marlise P. dos Santos; Howard Lesiuk; Cheemun Lum

Background and purpose Diffusion weighted imaging (DWI) may be used to evaluate post-coiling ischemia. Heparinization protocols for cerebral aneurysm coiling procedures differ among operators and centers, with little literature surrounding its effect on DWI lesions. The goal of this study was to determine which factors, including heparinization protocols, may affect DWI lesion load post-coiling. Materials and methods A review of 135 coiling procedures over 5 years at our centre was performed. Procedural data including length of procedure, number of coils used, stent or balloon assistance and operators were collected. Procedures were either assigned as using a bolus dose (>2000 U at any one time) or small aliquots of heparin (≤2000 U). Postprocedure DWI was reviewed and lesions were classified as small (< 5mm), medium (5–10 mm) or large (>10 mm). The cases were then classified into group 1 (≤5 small lesions) or group 2 (>5 small lesions or ≥1 medium or large lesion). Multivariate regression of the procedural variables for the two groups was calculated. A p value of <0.05 was considered significant. Results There were 78 procedures in group 1 and 57 procedures in group 2. Patients who received small aliquots (n=37) versus boluses of heparin (n=98) intraprocedurally had significantly greater frequency and size of DWI lesions (p=0.03). None of the other procedural variables was found to impact on lesion load. Conclusions More substantial DWI lesions were associated with small aliquots of heparin dosage compared with bolus doses. Heparin boluses should be preferentially administered during aneurysm coiling.


Journal of Clinical Epidemiology | 2016

Enriched administrative data can be used to retrospectively identify all known cases of primary subarachnoid hemorrhage

Shane W. English; Lauralyn McIntyre; Dean Fergusson; Alexis F. Turgeon; Cathy Sun; Marlise P. dos Santos; Cheemun Lum; John Sinclair; Alan J. Forster; Carl van Walraven

OBJECTIVE We derived and validated a method to screen all hospital admissions for 1° subarachnoid hemorrhage (SAH) by retrospectively implementing recognized diagnostic criteria. STUDY DESIGN AND SETTING A screen for 1° SAH was developed using two previously created registries. Screen-positive cases underwent diagnosis confirmation with primary record review. A review of all patient hospital encounters with the diagnostic code for 1° SAH, and cross-referencing with an existing SAH registry was undertaken to identify missed cases. RESULTS Three subscreens were combined to form the 1° SAH screen (sensitivity: 98.4% [95% CI: 91.7-99.7%], specificity: 93.4% [95% CI: 90.4-95.4%], n = 455 patients in validation sample). From 1,699 screen-positive admissions between July 1, 2002 and June 30, 2011, we identified 831 true cases of SAH of which 632 patients had 1° SAH from ruptured aneurysm/arteriovenous malformation (sensitivity: 96.5% [95% CI: 94.8-97.8%], specificity: 40.3% [95% CI: 38.1-42.6%]). A review of all encounters with a diagnostic code for 1° SAH yielded additional 22 true cases. CONCLUSION When positive, our 1° SAH screen significantly increases the probability of this diagnosis in a particular hospitalization. The addition of patient hospitalizations encoded with the diagnostic code for 1° SAH improved sensitivity. Together, these methods represent the best way to retrospectively identify all cases of 1° SAH within an extensive sampling frame.


Neurosurgical Focus | 2015

Imaging diagnosis and the role of endovascular embolization treatment for vascular intraspinal tumors

Marlise P. dos Santos; Jingwen Zhang; Diana Ghinda; Rafael Glikstein; Ronit Agid; Georges Rodesch; Donatella Tampieri; Karel G. terBrugge

Intraspinal tumors comprise a large spectrum of neoplasms, including hemangioblastomas, paragangliomas, and meningiomas. These tumors have several common characteristic imaging features, such as highly vascular mass appearance in angiography, hypointense rim and serpentine flow voids in MRI, and intense enhancement after intravenous contrast administration. Due to their rich vascularity, these tumors represent a special challenge for surgical treatment. More recently, the surgical treatment of intraspinal vascular tumors has benefited from the combination of endovascular techniques used to better delineate these lesions and to promote preoperative reduction of volume and tissue blood flow. Endovascular embolization has been proven to be a safe procedure that facilitates the resection of these tumors; hence, it has been proposed as part of the standard of care in their management.


Canadian Journal of Neurological Sciences | 2009

A rare case of cerebral cortical dysplasia with arterial vascular dysplasia.

Jai Jai Shiva Shankar; Susitna Trina Banerjee; Matthew J. Hogan; Karel G. terBrugge; Pierre Lasjaunias; Marlise P. dos Santos

BACKGROUND Cortical dysplasias are rarely associated with vascular anomalies. They are usually associated with venous anomalies or in few cases with both arterial and venous anomalies. METHODS Twenty-six year old female presented with history of headache showed cortical dysplasia associated with pure arterial dysplasia in the absence of any associated venous anomaly. CONCLUSIONS An abnormal arterial supply to or an abnormal venous drainage from the growing cortex may result in cortical rearrangements that eventually give rise to various neuronal migration anomalies.


Neurology | 2016

Subarachnoid hemorrhage admissions retrospectively identified using a prediction model.

Shane W. English; Lauralyn McIntyre; Dean Fergusson; Alexis F. Turgeon; Marlise P. dos Santos; Cheemun Lum; John Sinclair; Alan J. Forster; Carl van Walraven

Objective: To create an accurate prediction model using variables collected in widely available health administrative data records to identify hospitalizations for primary subarachnoid hemorrhage (SAH). Methods: A previously established complete cohort of consecutive primary SAH patients was combined with a random sample of control hospitalizations. Chi-square recursive partitioning was used to derive and internally validate a model to predict the probability that a patient had primary SAH (due to aneurysm or arteriovenous malformation) using health administrative data. Results: A total of 10,322 hospitalizations with 631 having primary SAH (6.1%) were included in the study (5,122 derivation, 5,200 validation). In the validation patients, our recursive partitioning algorithm had a sensitivity of 96.5% (95% confidence interval [CI] 93.9–98.0), a specificity of 99.8% (95% CI 99.6–99.9), and a positive likelihood ratio of 483 (95% CI 254–879). In this population, patients meeting criteria for the algorithm had a probability of 45% of truly having primary SAH. Conclusions: Routinely collected health administrative data can be used to accurately identify hospitalized patients with a high probability of having a primary SAH. This algorithm may allow, upon validation, an easy and accurate method to create validated cohorts of primary SAH from either ruptured aneurysm or arteriovenous malformation.


Rivista Di Neuroradiologia | 2015

Cerebral vascular malformations: Time-resolved CT angiography compared to DSA

Jai Jai Shiva Shankar; Cheemun Lum; Santanu Chakraborty; Marlise P. dos Santos

Purpose The purpose of this article is to prospectively test the hypothesis that time-resolved CT angiography (TRCTA) on a Toshiba 320-slice CT scanner enables the same characterization of cerebral vascular malformation (CVM) including arteriovenous malformation (AVM), dural arteriovenous fistula (DAVF), pial arteriovenous fistula (PAVF) and developmental venous anomaly (DVA) compared to digital subtraction angiography (DSA). Materials and methods Eighteen (eight males, 10 females) consecutive patients (11 AVM, four DAVF, one PAVF, and two DVA) underwent 19 TRCTA (Aquillion one, Toshiba) for suspected CVM diagnosed on routine CT or MRI. One patient with a dural AVF underwent TRCTA and DSA twice before and after treatment. Of the 18 patients, 13 were followed with DSA (Artis, Siemens) within two months of TRCTA. Twenty-three sequential volume acquisitions of the whole head were acquired after injection of 50 ml contrast at the rate of 4 ml/sec. Two patients with DVA did not undergo DSA. Two TRCTA were not assessed because of technical problems. TRCTAs were independently reviewed by two neuroradiologists and DSA by two other neuroradiologists and graded according to the Spetzler-Martin classification, Borden classification, overall diagnostic quality, and level of confidence. Weighted kappa coefficients (k) were calculated to compare reader’s assessment of DSA vs TRCTA. Results There was excellent (k = 0.83 and 1) to good (k = 0.56, 0.61, 0.65 and 0.67) agreement between the different possible pairs of neuroradiologists for the assessment of vascular malformations. Conclusion TRCTA may be a sufficient noninvasive substitute for conventional DSA in certain clinical situations.


Rivista Di Neuroradiologia | 2017

Neuroimaging of ocular involvement in patients with sickle cell disease and review of the literature

José Fernando Vallejo Diaz; Rafael Glikstein; Marlise P. dos Santos; Carlos Torres

Endophthalmitis is a rare cause of ocular infection that can be associated with immunocompromising conditions and, more rarely, with sickle cell disease. In this case report and review of the literature, we present a case of a young male with sickle cell disease who presented with rapidly progressive ocular pain, edema, erythema, and decreased visual acuity. The key radiological findings to suggest endophthalmitis were demonstrated using computed tomography and magnetic resonance imaging.


Academic forensic pathology | 2017

Fatal Entrapment of the Basilar Artery in a Longitudinal Fracture of the Clivus Due to Head Injury: A Case Report and Review of the Literature

Alfredo Walker; Marlise P. dos Santos; Rafael Glikstein; Jean Michaud

Infarction of the posterior cerebral artery circulation arising from entrapment of the basilar artery in a fracture of the clivus has been reported in the medical literature, predominantly in the radiology and emergency medicine journals. Review of the medical literature on the topic revealed 14 published cases of entrapment of the basilar and/or vertebral artery within a longitudinal fracture of the clivus. These were all reported between 1964 and 2016 and postmortem examination had been conducted on seven cases. To date, no case of entrapment of the basilar and/or vertebral artery in a fracture of the clivus has been reported in the forensic pathology literature, and the published literature on the entity is reviewed


Neuroradiology | 2011

Angiographic evaluation of the effect of intra-arterial milrinone therapy in patients with vasospasm from aneurysmal subarachnoid hemorrhage

Jai Jai Shiva Shankar; Marlise P. dos Santos; Leonardo de Deus-Silva; Cheemun Lum

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Alan J. Forster

Ottawa Hospital Research Institute

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Dean Fergusson

Ottawa Hospital Research Institute

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Lauralyn McIntyre

Ottawa Hospital Research Institute

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