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No abstract available Copyright © 2012 S. Karger AG, Basel [PUBLICATION ABSTRACT]

Atheromatous carotid plaque rupture is responsible for the majority of ischaemic strokes in the developed world. Plaque rupture has been associated with plaque morphology, plaque components’ properties, inflammation and local stress concentration. High resolution multi-spectral magnetic resonance imaging (MRI) has allowed the plaque components to be visualized in vivo. This study combined the recent advances in finite element analysis (FEA) and MRI, and performed stress analysis of five vulnerable carotid plaques based on the geometry derived from in vivo MRI. Image segmentation was based on multi-spectral MRI and co-registered with histology for plaque characterization. Plaque fibrous cap, lipid pool and vessel wall were modelled as isotropic, incompressible hyperelastic materials undergoing large deformation under pulse pressure loading. High stress concentrations were predicted at the shoulders and the thinnest fibrous cap regions of the plaque, and the mean maximal stresses were found to be higher in the ruptured plaques (683.3 kPa) than those in the unruptured plaques (226.9 kPa). The effect of the relative stiffness of fibrous cap to lipid pool on the stress within the cap itself was studied. It was shown that larger relative stiffness of fibrous cap to lipid pool resulted in higher stress within the cap. Thus, it is likely that high stress concentrations in vulnerable plaque may cause plaque rupture and lead to acute ischaemic sequelae. A combination of in vivo high resolution MRI and FEA could potentially act as a useful tool to assess plaque vulnerability and risk stratify patients with carotid atheroma.

Background:Inflammation is a recognised risk factor for the vulnerable atherosclerotic plaque. The aim of this study was to explore whether there is a difference in the degree of magnetic resonance (MR) defined inflammation using ultra small superparamagnetic iron oxide (USPIO) particles within carotid atheroma in completely asymptomatic individuals and the asymptomatic carotid stenosis contralateral to the symptomatic side.Methods:20 symptomatic patients with contralateral disease and 20 completely asymptomatic patients underwent multi-sequence MR imaging before and 36 h after USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant was calculated following USPIO administration. Mean signal change was compared across all quadrants in the two groups.Results:The mean percentage of quadrants showing signal loss was 53% in the contralateral group compared with 31% in completely asymptomatic individuals (p = 0.025). The mean percentages showing enhancement were 44% and 65%, respectively (p = 0.024). The mean signal difference between the two groups was 8.6% (95% CI 1.6% to 15.6%; p = 0.017).Conclusions:Truly asymptomatic plaques seem to demonstrate inflammation but not to the extent of the contralateral asymptomatic stenosis to the symptomatic side. Inflammatory activity may be a significant risk factor in asymptomatic disease.

Introduction Young children with significant ventricular dilatation or large intracranial fluid spaces often have a very thin cortical mantle as a result of persistently raised intracranial pressure. This rim of cortex has a tendency to fall away from the dura into the cavity during and after intracranial surgery, due to the lack of support, once the pressure in the fluid cavity has been reduced. This can lead to tearing of cortical bridging veins and the formation of post-operative subdural haematomas. Methods We describe a simple technique that attempts to prevent this phenomenon occurring using tissue glue. Once the craniotomy has been performed and the dura has been formally opened, tissue glue is applied to the underside of the dura around the edge of the wound, prior to corticotomy. Results and conclusion This results in the cortical mantle adhering to the undersurface of the dura and prevents the mantle from falling into the cavity either during the procedure or post-operatively.

Insertion of a ventriculoperitoneal shunt for hydrocephalus is one of the commonest neurosurgical procedures worldwide. Infection of the implanted shunt affects up to 15% of these patients, resulting in prolonged hospital treatment, multiple surgeries, and reduced cognition and quality of life. Our aim was to determine the clinical and cost-effectiveness of antibiotic (rifampicin and clindamycin) or silver shunts compared with standard shunts at reducing infection. In this parallel, multicentre, single-blind, randomised controlled trial, we included patients with hydrocephalus of any aetiology undergoing insertion of their first ventriculoperitoneal shunt irrespective of age at 21 regional adult and paediatric neurosurgery centres in the UK and Ireland. Patients were randomly assigned (1:1:1 in random permuted blocks of three or six) to receive standard shunts (standard shunt group), antibiotic-impregnated (0·15% clindamycin and 0·054% rifampicin; antibiotic shunt group), or silver-impregnated shunts (silver shunt group) through a randomisation sequence generated by an independent statistician. All patients and investigators who recorded and analysed the data were masked for group assignment, which was only disclosed to the neurosurgical staff at the time of operation. Participants receiving a shunt without evidence of infection at the time of insertion were followed up for at least 6 months and a maximum of 2 years. The primary outcome was time to shunt failure due the infection and was analysed with Fine and Gray survival regression models for competing risk by intention to treat. This trial is registered with ISRCTN 49474281. Between June 26, 2013, and Oct 9, 2017, we assessed 3505 patients, of whom 1605 aged up to 91 years were randomly assigned to receive either a standard shunt (n=536), an antibiotic-impregnated shunt (n=538), or a silver shunt (n=531). 1594 had a shunt inserted without evidence of infection at the time of insertion (533 in the standard shunt group, 535 in the antibiotic shunt group, and 526 in the silver shunt group) and were followed up for a median of 22 months (IQR 10–24; 53 withdrew from follow-up). 32 (6%) of 533 evaluable patients in the standard shunt group had a shunt revision for infection, compared with 12 (2%) of 535 evaluable patients in the antibiotic shunt group (cause-specific hazard ratio [csHR] 0·38, 97·5% CI 0·18–0·80, p=0·0038) and 31 (6%) of 526 patients in the silver shunt group (0·99, 0·56–1·74, p=0·96). 135 (25%) patients in the standard shunt group, 136 (25%) in the antibiotic shunt group, and 140 (27%) in the silver shunt group had adverse events, which were not life-threatening and were mostly related to valve or catheter function. The BASICS trial provides evidence to support the adoption of antibiotic shunts in UK patients who are having their first ventriculoperitoneal shunt insertion. This practice will benefit patients of all ages by reducing the risk and harm of shunt infection. UK National Institute for Health Research Health Technology Assessment programme.

Background: Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The role of calcium deposition and its contribution to plaque stability is controversial. This study uses both an idealized and a patient-specific model to evaluate the effect of a calcium deposit on the stress distribution within an atheromatous plaque. Methods: Using a finite-element method, structural analysis was performed on an idealized plaque model and the location of a calcium deposit within it was varied. In addition to the idealized model, in vivo high-resolution MR imaging was performed on 3 patients with carotid atheroma and stress distributions were generated. The individual plaques were chosen as they had calcium at varying locations with respect to the lumen and the fibrous cap. Results: The predicted maximum stress was increased by 47.5% when the calcium deposit was located in the thin fibrous cap in the model when compared with that in a model without a deposit. The result of adding a calcium deposit either to the lipid core or remote from the lumen resulted in almost no increase in maximal stress. Conclusion: Calcification at the thin fibrous cap may result in high stress concentrations, ultimately increasing the risk of plaque rupture. Assessing the location of calcification may, in the future, aid in the risk stratification of patients with carotid stenosis.

This thesis examines the significance of funerary practices and monuments dating to the Late Neolithic and Early Bronze Age in and around the Wylye Valley to the west of Stonehenge. This has been conducted through the re-evaluation of the work of Sir Richard Colt Hoare and the production of a database and Geographical Information System using the Wiltshire Sites and Monuments Record. The motivation behind why the monuments were positioned where they were has been attempted through spatial analysis within the GIS. The critical examination of the primary excavation data is based on modern interpretive frameworks and the interpretations which have been formed are re-examined to meet new thinking. The results of the thesis indicate the concentration of barrows towards the top of the valley on the northern escarpment and the clustering of barrows around older features in the landscape. This is similar to the spatial patterns observed nationally, supporting previous research and the interpretations drawn, though there appears to be a higher concentration of primary cremations and more nucleated cemeteries in the Wylye Valley area which may indicate local trends.

Stroke is the third leading cause of death and morbidity in the Western world. Ever since the publication of the major randomized trials showing the benefit of thrombolysis in early acute stroke, there has been growing impetus for the diagnosis of acute stroke to become a medical emergency. Currently, computed tomography (CT) remains the diagnostic method of choice in the assessment of acute strokes. It is practical, rapid, and widely available and, as used in these trials, can robustly exclude acute hemorrhage before potential thrombolysis. Although magnetic resonance imaging (MRI) has a number of advantages over unenhanced CT, the practicalities of performing MRI in the acute setting have hampered its widespread use. There are several reasons why speed of imaging is paramount in acute strokes. Firstly, such patients are often unwell and agitated and, as such, require close monitoring. Moreover, because of the short window within which intravenous thrombolysis can be given, time-consuming imaging studies decrease the therapeutic options available and likelihood of successful intervention. This review summarizes the latest developments in ultrafast imaging protocols that have the potential to improve practical feasibility, and thus propel MRI back to the forefront of acute stroke imaging.