Tetrahedral Image-to-Mesh Conversion Software for Anatomic Modeling of Arteriovenous Malformations

We describe a new implementation of an adaptive multi-tissue tetrahedral mesh generator targeting anatomic modeling of Arteriovenous Malformation (AVM) for surgical simulations. Our method, initially constructs an adaptive Body-Centered Cubic (BCC) mesh of high quality elements. Then, it deforms the mesh surfaces to their corresponding physical image boundaries, hence, improving the mesh fidelity and smoothness. Our deformation scheme, which builds upon the ITK toolkit, is based on the concept of energy minimization, and relies on a multi-material point-based registration. It uses non-connectivity patterns to implicitly control the number of the extracted feature points needed for the registration, and thus, adjusts the trade-off between the achieved mesh fidelity and the deformation speed. While many medical imaging applications require robust mesh generation, there are few codes available to the public. We compare our implementation with two similar open-source image-to-mesh conversion codes: (1) Cleaver from US, and (2) CGAL from EU. Our evaluation is based on five isotropic/anisotropic segmented images, and relies on metrics like geometric & topologic fidelity, mesh quality, gradation and smoothness. The implementation we describe is open- source and it will be available within: (i) the 3D Slicer package for visualization and image analysis from Harvard Medical School, and (ii) an interactive simulator for neurosurgical procedures involving vasculature using SOFA, a framework for real-time medical simulation developed by INRIA

A New Window for the Treatment of Posterior Cerebral Artery, Superior Cerebellar Artery, and Basilar Apex Aneurysm: The Expanded Endoscopic Endonasal Approach

To explore the feasibility of an endoscopic endonasal transclival approach to treat aneurysms arising in the basilar apex, posterior cerebral arteries, and superior cerebellar arteries

ACUTE RELATIVE ADRENAL INSUFFICIENCY AFTER ANEURYSMAL SUBARACHNOID HEMORRHAGE

ABSTRACT OBJECTIVE The hypothalamic-pituitary-adrenal axis is an important part of the body's natural response to acute illness. Adrenal insufficiency has the potential to lead to hemodynamic instability and electrolyte imbalances, limit the body's ability to respond to stress, and worsen overall clinical outcome. In this case series, we describe 16 patients evaluated for acute adrenal insufficiency after aneurysmal subarachnoid hemorrhage. CLINICAL PRESENTATION Over a 2-year period, the medical records of 16 patients admitted to the adult neurosurgery service for aneurysmal subarachnoid hemorrhage who were nonresponsive to vasopressor therapy and received cosyntropin for the evaluation of adrenal insufficiency within 14 days of their event were reviewed. INTERVENTION The median baseline cortisol in this population was 22.5 μg/dL, with a poststimulation cortisol level of 31 μg/dL. Of the population surveyed, a total of 11 patients met the preestablished criteria for adrenal insufficiency, 3 with baseline cortisol levels of less than 15 μg/dL and 11 with poststimulation concentration changes of less than 9 μg/dL. Baseline serum cortisol concentrations were significantly correlated with hospital stay (P = 0.045), intensive care unit stay (P = 0.005), and ventilator days (P = 0.006). CONCLUSION To date, this is the only investigation evaluating the incidence of acute relative adrenal insufficiency in this population. In our cohort, 69% of the patients met the preestablished criteria for relative adrenal insufficiency. The impact of low-dose corticosteroid therapy in this population also needs review, as it could have significant implications for the management of cerebral vasospasm

Ruptured Arteriovenous Malformation Presenting with Kernohan’s Notch

AVMs are congenital lesions that predispose patients to intracranial hemorrhage and resultant neurological deficits. These deficits are often focal and due to the presence of local neurologic disruption from hemorrhage in the contralateral cerebral hemisphere. We present a rare case of a patient with ipsilateral neurological deficits due to Kernohan’s Notch phenomenon resulting from hemorrhage from an AVM. A 31-year-old woman with seizures underwent MR and angiographic imaging which confirmed an unruptured left parietal AVM. The patient declined treatment and presented with obtundation 4 years later. Imaging revealed an acute left parietal ICH and SDH with significant mass effect. The patient underwent emergent hemicraniectomy and hematoma evacuation. Postoperatively, she made significant improvement and was following commands contralaterally with ipsilateral hemiplegia. MR imaging revealed right Kernohan’s Notch. The patient had significant rehabilitation with neurological improvement. She eventually underwent elective embolization followed by subsequent surgical resection and bone replacement. Three years from the initial hemorrhage, the patient had only mild left-sided weakness and ambulates without assistance. A false localizing sign, Kernohan’s Notch phenomenon, should be considered in the setting of AVM hemorrhage with paradoxical motor impairment and can be identified through MRI

A New Window for the Treatment of Posterior Cerebral Artery, Superior Cerebellar Artery, and Basilar Apex Aneurysm: The Expanded Endoscopic Endonasal Approach

OBJECTIVE:  To explore the feasibility of an endoscopic endonasal transclival approach to treat aneurysms arising in the basilar apex, posterior cerebral arteries, and superior cerebellar arteries. STUDY DESIGN:  Cadaveric anatomical study. PARTICIPANTS:  Fifteen cadaveric specimens. MAIN OUTCOME MEASURES:  Degree of surgical exposure of each artery attained, distance from the nasal vestibule to these three arteries, and feasibility of clipping these vessels using standard vascular clip applicators. RESULTS:  Both posterior cerebral arteries were exposed, 0.67 cm (standard deviation [SD]: 0.2) on the right side and 0.59 cm (SD: 0.2) on the left side. Both right and left superior cerebral arteries were exposed, 0.6 cm (SD: 0.2) and 0.7 cm (SD: 0.3), respectively. The length of the basilar artery exposed was 2.6 cm (SD: 0.3). The distance from the nasal vestibule to the posterior cerebral artery, superior cerebellar artery, and basilar apex was 10 cm with an SD of ± 0.7, 0.6, and 0.8 cm, respectively. We were able to apply clips on each of these three vessels with a minimal alteration of surrounding normal tissue. CONCLUSION:  The endoscopic endonasal transclival approach represents a potentially feasible surgical corridor to treat aneurysms arising from these vessels