Blood flow in intracranial aneurysms treated with Pipeline embolization devices: computational simulation and verification with Doppler ultrasonography on phantom models

PURPOSE: The aim of this study was to validate a computational fluid dynamics (CFD) simulation of flow-diverter treatment through Doppler ultrasonography measurements in patient-specific models of intracranial bifurcation and side-wall aneurysms. METHODS: Computational and physical models of patient-specific bifurcation and sidewall aneurysms were constructed from computed tomography angiography with use of stereolithography, a three-dimensional printing technology. Flow dynamics parameters before and after flow-diverter treatment were measured with pulse-wave and color Doppler ultrasonography, and then compared with CFD simulations. RESULTS: CFD simulations showed drastic flow reduction after flow-diverter treatment in both aneurysms. The mean volume flow rate decreased by 90% and 85% for the bifurcation aneurysm and the side-wall aneurysm, respectively. Velocity contour plots from computer simulations before and after flow diversion closely resembled the patterns obtained by color Doppler ultrasonography. CONCLUSION: The CFD estimation of flow reduction in aneurysms treated with a flow-diverting stent was verified by Doppler ultrasonography in patient-specific phantom models of bifurcation and side-wall aneurysms. The combination of CFD and ultrasonography may constitute a feasible and reliable technique in studying the treatment of intracranial aneurysms with flow-diverting stents.

Failure of Flow Diverter Treatment of Intracranial Aneurysms Related to the Fetal-type Posterior Communicating Artery / 신경중재치료의학

PURPOSE: The pipeline embolization device (PED) is a flow diverter that has shown promise in the treatment of intracranial aneurysms. Close to one-fifth of aneurysms, however, fail to occlude after PED placement. This study aims to identify anatomical features and clinicopathologic factors that may predispose failed aneurysm occlusion with the PED. MATERIALS AND METHODS: We retrospectively reviewed all anterior circulation unruptured saccular aneurysms treated with the PED in a single-center. The primary outcome measure was angiographic occlusion. Anatomical features and potential predictors, including gender, aneurysm location, size, height, aspect ratio, neck width, prior treatment and the number of PED, were studied using binary logistic regression. RESULTS: 29 anterior circulation unruptured saccular aneurysms with a mean size of 6.99 mm treated with the PED in a single center were retrospectively studied. The overall occlusion rate was 79.3% after a mean follow-up of 9.2 months. Four aneurysms were related to the fetal-type posterior communicating artery (PComA), and all were refractory to flow diverter treatment. Female gender was significantly associated with a higher occlusion rate. We present the anatomical features and propose possible pathophysiological mechanisms of these PComA aneurysms that failed flow diverter treatment. CONCLUSION: A PComA aneurysm with persistent fetal-type circulation appears to be particularly refractory to flow diverter treatment, especially when the aneurysm incorporates a significant portion of the PComA. Our experience suggested that flow diverting stents alone may not be the ideal treatment for this subgroup of aneurysms, and alternative modalities should be considered. Female patients were found to have a significantly higher rate of treatment success.

Supratentorial Intraparenchymal Haemorrhages during Spine Surgery

Intracranial haemorrhages are rare but potentially life-threatening complications of spine surgery. Most reported cases involved subdural or cerebellar haemorrhages; supratentorial parenchymal bleeding is very uncommon. We report a 28-year-old woman who underwent resection of a thoracic Ewing's sarcoma, and developed fatal haemorrhages around her cerebral metastases during surgery. The clinical presentations, possible pathogenesis and potential preventive measures are discussed. Patients with disseminated metastases within the neural axis are at risks of intracranial complications during spine surgery. The presence of intracranial mass lesions should be considered as a relative contraindication to intradural spine surgery.

Patient safety culture among medical students in Singapore and Hong Kong

<p><b>INTRODUCTION</b>Undergraduate education in medical schools plays an important role in promoting patient safety. Medical students from different backgrounds may have different perceptions and attitudes toward issues concerning safety. This study aimed to investigate whether patient safety cultures differed between students from two Asian countries, and if they did, to find out how they differed. This study also aimed to identify the educational needs of these students.</p><p><b>METHODS</b>A voluntary, cross-sectional and self-administered questionnaire survey was conducted on 259 students from two medical schools - one in Hong Kong and the other in Singapore. None of the students had received any formal teaching on patient safety. We used a validated survey instrument, the Attitudes to Patient Safety Questionnaire III (APSQ-III), which was designed specifically for students and covered nine key factors of patient safety culture.</p><p><b>RESULTS</b>Of the 259 students, 81 (31.3%) were from Hong Kong and 178 (68.7%) were from Singapore. The overall response rate was 66.4%. Significant differences between the two groups of students were found for two key factors - 'patient safety training', with Hong Kong students being more likely to report having received more of such training (p = 0.007); and 'error reporting confidence', which Singapore students reported having less of (p < 0.001). Both groups considered medical errors as inevitable, and that long working hours and professional incompetence were important causes of medical errors. The importance of patient involvement and team functioning were ranked relatively lower by the students.</p><p><b>CONCLUSION</b>Students from different countries with no prior teaching on patient safety may differ in their baseline patient safety cultures and educational needs. Our findings serve as a reference for future longitudinal studies on the effects of different teaching and healthcare development programmes.</p>

Diagnostic accuracy of Focused Abdominal Sonography for Trauma in blunt abdominal trauma patients in a trauma centre of Hong Kong / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>Focused Abdominal Sono-graphy for Trauma (FAST) is widely used for the detection of intraperitoneal free fluids in patients suffering from blunt abdominal trauma (BAT). This study aimed at assessing the diagnostic accuracy of this investigation in a designated trauma centre.</p><p><b>METHODS</b>This was a retrospective study of BAT patients over a 6 year period seen in a trauma centre in Hong Kong. FAST findings were compared with laparotomy, abdominal computed tomography or autopsy findings, which served as the gold standard for presence of intraperitoneal free fluids. The patients who did not have FAST or gold standard confirmatory test performed, had preexisting peritoneal fluid, died at resuscitation or had imcomplete documentation of FAST findings were excluded. The performance of FAST was expressed as sensitivity, specificity, predictive values (PV), likelihood ratios (LR) and accuracy.</p><p><b>RESULTS</b>FAST was performed in 302 patients and 153 of them were included in this analysis. The sensitivity, specificity, positive PV, negative PV, positive LR, negative LR and accuracy for FAST were respectively 50.0%, 97.3%, 87.0%, 84.6%, 18.8, 0.5 and 85.0%. FAST was found to be more sensitive in less severely injured patients and more specific in more severely injured patients.</p><p><b>CONCLUSION</b>FAST is a reliable investigation in the initial assessment of BAT patients. The diagnostic values of FAST could be affected by the severity of injury and staff training is needed to further enhance its effective use. Key words: Laparotomy; Autopsy; Tomography, X-ray computed; Tomography, spiral computed; Ultrasonography.</p>