Hyundo Shin

Surgical management of spinal cord haemangioblastoma

SummaryBackground. The surgical management of spinal cord haemangioblastomas is distinct from that of other benign spinal cord tumours and optimal surgical strategy is still being determined because of the rarity of the condition. The aim of this study is to investigate factors that affect the outcome of surgical management. Patients and methods. We retrospectively analysed 24 operations for symptomatic spinal cord haemangioblastomas in 20 patients. Clinical features and surgical results were investigated by medical record review, telephone interviews, angiographic images, and magnetic resonance images (MRI). The mean follow-up period was 5.6 years (range 6 months to 13.6 years). Results. Patients with cystic components showed pre-operative motor weakness and sensory change more commonly than those without cystic components. Post-operative function scale had a positive correlation with pre-operative function (R2 = 0.727; p < 0.001) and no correlation with the extent of the surgery. All subtotally removed tumours recurred, whereas totally removed tumours recurred in only 3 patients. Conclusion. The cystic component of spinal cord haemangioblastomas is responsible for symptom generation and is helpful for dissecting tumours. Post-operative functional status is determined by pre-operative functional status. Total removal is feasible by using the correct surgical technique and is recommended to prevent recurrence.

A systematic approach to enhance off-axis directional electromagnetic wave by two-dimensional structure design

In this study, we propose a two-dimensional (2D) dielectric structure tailored by a systematic design approach on the exit side of a metallic aperture to enhance the off-axis electromagnetic (EM) wave. We adopted a phase field method based topology optimization scheme and designed an arbitrary 2D dielectric structure in order to steer outward beaming through an aperture to a specific direction. Beyond previous one-dimensional structure, we proposed an arbitrary 2D dielectric structure through the introduced design process defining not only x- but also y-directional dielectric structural boundaries simultaneously and experimentally confirmed enhanced EM wave transmission to a desired direction.

Progressive collapse of PMMA-augmented vertebra: a report of three cases.

Vertebroplasty using polymethylmethacrylate (PMMA) for augmentation is accepted as a safe and effective treatment for vertebral compression fracture. However, various complications related to PMMA vertebroplasty have recently been reported. We experienced three cases with progressive collapse of PMMA-augmented vertebra. Collapse progressed after augmentation in cases where PMMA conglomerated without contiguous bone interdigitation. A high viscosity of the PMMA preparation and vertebral body cavitory lesion may play a role in progressive vertebral collapse. To avoid this complication, bone cement should be injected sufficiently and permeate to contiguous bone to create strong support and anchorage.

Topological Design Approach for Quadruple-Ridge Aperture Configuration

We present a systematic approach for topological design of a high transmission metallic nano-aperture. The layout of the metallic layer is determined by the ON/OFF design method to maximize the norm value of the near-field intensity. Combined with the numerical finite element method, we derive a quadruple-ridge aperture composed of bowtie like shape with adjoining holes, and numerical results show that the location of the holes affects not only the transmission peak intensity, but also the field confinement because of the surface wave reflected from the adjoining holes. Results verify that the ON/OFF method to be a useful tool for obtaining an effective aperture shape.