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Biomedical subjects

Michael D Cusimano

Publications and source records attributed to Michael D Cusimano.

14 recordsLinked to original sources
PubMed2006

The orbitozygomatic approach.

OBJECTIVE: The orbitozygomatic approach is a modification and extension of the pterional craniotomy to gain a wider exposure of structures at a cranial base. To simplify the understanding and performance of the approach, we developed a teaching video that follows a systematic approach to the surgical anatomy and technique. METHODS: The authors have incorporated three-dimensional (3D) renderings into the descriptions of the surgical technique and contemporary computer animation is used to demonstrate surgical details and nuances of the procedure. RESULTS: A teaching video was compiled, and it was well received by neurosurgical residents in Europe and Canada. CONCLUSION: With mastery in the surgical laboratory and with guided supervision, the approach can be routinely applied without adding morbidity to a variety of pathologies such as aneurysms and tumors.

Brain Diseases↗
PubMed2005

A randomized trial of teaching bioethics to surgical residents.

BACKGROUND: Bioethics education has been recommended as a formal component of surgical residency training. The best method for teaching bioethics to residents is unclear. We compared the effectiveness of a standardized patient (SP)-based seminar to a traditional seminar format for teaching bioethics to surgical residents. METHODS: We randomized 31 first- and second-year surgical residents to either a SP-based seminar or a traditional seminar on informed consent. Immediately after the seminars, we evaluated resident performance in patient encounters on informed consent by using an objective structured clinical examination. Their knowledge of informed consent was also evaluated by using a 20-question short-answer written examination immediately after the seminars and then 3 weeks later. RESULTS: Twenty-nine residents completed the study; two withdrew because of an emergency. The SP seminar group had lower SP interview scores on the 22 item checklist compared with the traditional seminar group (57% versus 66%; difference -9%; 95% confidence interval [CI], -17% to -1%, P=.03). The SP seminar group also had lower knowledge scores on the questionnaire immediately after the seminar (60% versus 73%; difference -13%; 95% CI, -21% to -4%, P=.003). The difference in knowledge scores persisted at 3 weeks (41% for the SP group, 59% for the traditional seminar group; difference -18%; 95% CI, -29% to -7%; P=.002). CONCLUSIONS: A traditional seminar was superior to an SP-based seminar for teaching informed consent to surgical residents.

Adult↗
PubMed2004

Identification of human brain tumour initiating cells.

The cancer stem cell (CSC) hypothesis suggests that neoplastic clones are maintained exclusively by a rare fraction of cells with stem cell properties. Although the existence of CSCs in human leukaemia is established, little evidence exists for CSCs in solid tumours, except for breast cancer. Recently, we prospectively isolated a CD133+ cell subpopulation from human brain tumours that exhibited stem cell properties in vitro. However, the true measures of CSCs are their capacity for self renewal and exact recapitulation of the original tumour. Here we report the development of a xenograft assay that identified human brain tumour initiating cells that initiate tumours in vivo. Only the CD133+ brain tumour fraction contains cells that are capable of tumour initiation in NOD-SCID (non-obese diabetic, severe combined immunodeficient) mouse brains. Injection of as few as 100 CD133+ cells produced a tumour that could be serially transplanted and was a phenocopy of the patient's original tumour, whereas injection of 10(5) CD133- cells engrafted but did not cause a tumour. Thus, the identification of brain tumour initiating cells provides insights into human brain tumour pathogenesis, giving strong support for the CSC hypothesis as the basis for many solid tumours, and establishes a previously unidentified cellular target for more effective cancer therapies.

AC133 Antigen↗
PubMed2004

Consistency of standards and stability of pass/fail decisions with examinee-based standard-setting methods in a small-scale objective structured clinical examination.

PROBLEM STATEMENT AND BACKGROUND: The apparent feasibility and the face validity of the examinee-based methods such as the borderline-group methods provide support for their increasing adoption by health profession schools. Before that can occur, however, more information on the quality of the standards produced by these techniques is required. The purpose of the present study was to assess the quality of the standards produced on a small-scale objective structured clinical examination (OSCE) by the borderline-group and contrasting-groups examinee-based standard-setting procedures. METHOD: These two examinee-based criterion-referenced standard-setting procedures were done for an undergraduate fourth-year surgical OSCE and the consistency of the standards and the decisions arising from the standards were assessed. RESULTS: Both techniques provided consistent and realistic standards. CONCLUSIONS: There is sufficient theoretical and empirical evidence to support the use of examinee-based standard-setting techniques in small-scale OSCEs that use expert examiners.

Clinical Clerkship↗
PubMed2003

Foramen magnum meningiomas: concepts, classifications, and nuances.

Foramen magnum meningiomas represent a common histological tumor in a rare and eloquent location. The authors review the clinical presentation, relevant anatomical details of the foramen magnum region, neuroimaging features, the posterior and posterolateral surgical approaches for resection, and outcomes. Based the experiences of the senior author (M.D.C.) and a review of the literature, they introduce the concept of a "surgical corridor," discuss the classification of these tumors, and the nuances of care for patients with these challenging lesions.

Foramen Magnum↗
PubMed2003

Anatomical basis of approaches to foramen magnum and lower clival meningiomas: comparison of retrosigmoid and transcondylar approaches.

OBJECT: Meningiomas of the lower clivus and foramen magnum are among the most challenging of all neurosurgical lesions. Debate continues regarding the most appropriate approach to this eloquent anatomical region. This anatomical study was undertaken to measure and compare the area of surgical exposures of the lower clivus achieved using the retrosigmoid and the extreme-lateral transcondylar (ELT) approaches. METHODS: Thirteen embalmed cadaveric heads were dissected bilaterally via the retrosigmoid approach on one side and the ELT approach on the other. The circumference of the area of exposure was delineated using beaded pins placed into the dura. After removal of the brain, the longest longitudinal and transverse axes of the pinned areas were measured and surface area calculated. The area of surgical exposure was also expressed as a percentage of the total area of the lower clivus. Normalized and adjusted surface areas were calculated using the bimastoid diameter. The areas of exposure were compared using the two-tailed paired Student t-test. The mean area of exposure required using the retrosigmoid approach was 19.8 +/- 14.7 mm2 (range 6-49 mm2) and that using the ELT approach was 27.8 +/- 22.8 mm2 (range 10-90 mm2). The mean percentage of the lower clivus exposed by the retrosigmoid approach was 14.9 +/- 3.6% (range 10-22%) and that exposed by the ELT approach was 20.5 +/- 4.9% (range 10-25%). The ELT approach provided significantly greater area of operative exposure and allowed a significantly higher percentage of lower clivus and foramen magnum exposure than did the retrosigmoid approach (p < 0.05). Normalized and adjusted surface areas, taking into consideration the bimastoid diameter, were also statistically significant in favor of the ELT approach. CONCLUSIONS: The ELT approach provided a significantly greater area of exposure than did the retrosigmoid approach.

Cranial Fossa, Posterior↗
PubMed2003

Imaging of murine brain tumors using a 1.5 Tesla clinical MRI system.

BACKGROUND: In this study, we investigated the feasibility of using a 1.5 Tesla (T) clinical magnetic resonance imaging (MRI) system for in vivo assessment of three histopathologically different brain tumor models in mice. METHODS: We selected mouse models in which tumor growth was observed in different intracranial compartments: Patched+/- heterozygous knock-out mice for tumor growth in the cerebellum (n = 5); U87 MG human astrocytoma cells xenografted to the frontal lobe of athymic mice (n = 15); and F5 (n = 15) or IOMM Lee (n = 15) human malignant meningioma cells xenotransplanted to the athymic mouse skull base or convexity. Mice were imaged using a small receiver surface coil and a clinical 1.5 T MRI system. T1- and fast spin echo T2-weighted image sequences were obtained in all animals. Gadolinium was injected via tail vein to better delineate the intracranial tumors. Twenty mice were followed by serial MRI to study tumor growth over time. In these mice, images were typically performed after tumor implantation, and at two week intervals. Mice were euthanized following their last imaging procedure, and their tumors were examined by histopathology. The histopathological preparations were then compared to the last MR images to correlate the imaging features with the pathology. RESULTS: Magnetic resonance imaging delineated th tumors in the cerebellum, frontal lobes and skull base in all mouse models. The detection of intracranial tumors was enhanced with prio administration of gadolinium, and the limit of resolution of brain tumors in the mice was 1-2 mm3. Sequential images performed at different time intervals showed progressive tumor growth in all animals. The MR images of tumor size and location correlated accurately with th results of the histopathological analysis. CONCLUSION: Magnetic resonance imaging of murine brain tumors in different intracrania compartments is feasible with a 1.5 T clinical MR system and a specially designed surface coil. Tumors as small as 1-2 mm3 can be detecte with good image resolution. Mice harbouring nascent brain tumors can be followed sequentially by serial MR imaging. This may allow for a noninvasive means by which tumor growth can be measured, and novel therapies tested without resorting to sacrifice of the mice.

Animals↗
PubMed2003

The effect of incorporating normative data into a criterion-referenced standard setting in medical education.

PURPOSE: Determining standards for assessing clinical performance is a controversial issue. Purely item-based methods such as the Angoff method often produce unrealistic judgments, even when used by experienced judges. The rather unstudied compromise methods combine absolute and relative judgments and thereby incorporate normative data into criterion-based standard-setting judgments. The purpose of this study was to compare the quality and implications of standards set by three methods used for the Objective Structured Clinical Examination (OSCE). METHOD: Ninety-six judges set standards for 36 surgical year-4 undergraduate OSCE stations. All judges had normative student performance data when judgments were made with the Angoff, Ebel, or Hofstee methods. RESULTS: The Hofstee method gave more realistic cutoff scores and standard errors and better Meskauskas and Jaeger indices than the Angoff and Ebel methods. CONCLUSIONS: Medical educators setting standards for an OSCE should consider adopting the Hofstee method.

Clinical Clerkship↗
PubMed2002

Effect of visual-spatial ability on learning of spatially-complex surgical skills.

Visual-spatial ability is thought to be important in competency in specific surgical procedures. To test this hypothesis, 37 surgical residents completed six tests of visual-spatial ability, ranging from low-level to high-level visual processing. Using previously validated and objective instruments, we then assessed their ability to complete and learn a spatially-complex surgical procedure. Residents with higher visual-spatial scores in the form-board test and the mental-rotations test did significantly better in the procedure than did those with lower scores. After practice and feedback, residents with lower scores achieved a comparable level of competency. Our results suggest that visual-spatial ability is related to competency and quality of results in complex surgery, and could potentially be used in resident selection, career counselling, and training.

Animals↗
PubMed2002

The effect of bench model fidelity on endourological skills: a randomized controlled study.

PURPOSE: Complex skills, such as ureteroscopy and stone extraction, are increasingly taught to novice urology trainees using bench models in surgical skills laboratories. We determined whether hands-on training improved the performance of novices more than those taught only by a didactic session and whether there was a difference in the performance of subjects taught on a low versus a high fidelity model. MATERIALS AND METHODS: We randomized 40 final year medical students to a didactic session or 1 of 2 hands-on training groups involving low or high fidelity bench model practice. Training sessions were supervised by experienced endourologists. Testing involved removal of a mid ureteral stone using a semirigid ureteroscope and a basket. Blinded examiners tested subjects before and after training. Performance was measured by a global rating scale, checklist, pass rating and time needed to complete the task. RESULTS: There was a significant effect of hands-on training on endourological performance (p <0.01). With respect to bench model fidelity the low fidelity group did significantly better than the didactic group (p <0.05). However, no significant difference was found between the high and low fidelity groups (p >0.05). The low fidelity model cost Canadian $20 to produce, while the high fidelity model cost Canadian $3,700 to purchase. CONCLUSIONS: Hands-on training using bench models can be successful for teaching novices complex endourological skills. A low fidelity bench model is a more cost-effective means of teaching ureteroscopic skills to novices than a high fidelity model.

Clinical Competence↗