Leptomeningeal collateralization in acute ischemic stroke: Impact on prominent cortical veins in susceptibility-weighted imaging.

BACKGROUND The extent of hypoperfusion is an important prognostic factor in acute ischemic stroke. Previous studies have postulated that the extent of prominent cortical veins (PCV) on susceptibility-weighted imaging (SWI) reflects the extent of hypoperfusion. Our aim was to investigate, whether there is an association between PCV and the grade of leptomeningeal arterial collateralization in acute ischemic stroke. In addition, we analyzed the correlation between SWI and perfusion-MRI findings. METHODS 33 patients with acute ischemic stroke due to a thromboembolic M1-segment occlusion underwent MRI followed by digital subtraction angiography (DSA) and were subdivided into two groups with very good to good and moderate to no leptomeningeal collaterals according to the DSA. The extent of PCV on SWI, diffusion restriction (DR) on diffusion-weighted imaging (DWI) and prolonged mean transit time (MTT) on perfusion-imaging were graded according to the Alberta Stroke Program Early CT Score (ASPECTS). The National Institutes of Health Stroke Scale (NIHSS) scores at admission and the time between symptom onset and MRI were documented. RESULTS 20 patients showed very good to good and 13 patients poor to no collateralization. PCV-ASPECTS was significantly higher for cases with good leptomeningeal collaterals versus those with poor leptomeningeal collaterals (mean 4.1 versus 2.69; p=0.039). MTT-ASPECTS was significantly lower than PCV-ASPECTS in all 33 patients (mean 1.0 versus 3.5; p<0.00). CONCLUSIONS In our small study the grade of leptomeningeal collateralization correlates with the extent of PCV in SWI in acute ischemic stroke, due to the deoxyhemoglobin to oxyhemoglobin ratio. Consequently, extensive PCV correlate with poor leptomeningeal collateralization while less pronounced PCV correlate with good leptomeningeal collateralization. Further SWI is a very helpful tool in detecting tissue at risk but cannot replace PWI since MTT detects significantly more ill-perfused areas than SWI, especially in good collateralized subjects.

The Social Imaginary of Culture/Civilization in the Arabic Literary Tradition

Charles Taylor’s contribution to social imaginaries offers an interpretive framework for better understanding modernity as secularity. One of its main aspects is conceiving of human society in linear, homogenous time (secular time). Looking into the Arabic intellectual tradition, I will argue in my paper that Taylor’s framework can help us understand major social and intellectual transformations. The Ottoman and Arabic modernization process during the 19th century has often been understood by focusing on certain core concepts. One of these is tamaddun, usually translated as “civilization.” I will be mostly talking about the works of two “pioneers” of Arab modernity (which is traditionally referred to as an-nahḍa, the so-called Arab Renaissance): the Syrian Fransīs Marrāsh and the Egyptian Rifāʿa aṭ-Ṭahṭāwī. First I will focus on Marrāsh’s didactic novel “The Forest of Truth” (1865), as it offers a complex view of tamaddun, which has sometimes been construed as merely a social and political reform program. The category of "social imaginary,” however, is useful in grasping the wider semantic scope of this concept, which is reading it as a signifier for human history conceived of in secular time, as Taylor defines it. This conceptualization of human history functioning within the immanent frame can also be observed in the introduction to “The Extraction of Pure Gold in the Description of Paris” (1834), a systematic account of a travel experience in France that was written by the other “pioneer,” aṭ-Ṭahṭāwī. Finally, in translating tamaddun as “the modern social imaginary of civilization/culture,” the talk aims to consider this imaginary as a major factor in the emergence of the “secular age.” Furthermore, it suggests the importance of studying (quasi-) literary texts, such as historiographical, geographical, and self-narratives in the Arabic literary tradition, in order to further elaborate continuities and ruptures in social imaginaries.

On "Renaissance" and "culture" and their Jewish applications : presitential address to the Union of Jewish Literary Societies by the Chief Rabbi, Monday, March 1st, 5675 - 1915 at University College, London

[Joseph Herman Hertz]

Russian Literature and the Jew : a sociological inquiry into the nature and origin of literary patterns

by Joshua Kunitz

Literary history of Hebrew grammarians and lexicographers ...

by Hartwig Hirschfeld

The Karaite literary opponents of Saadiah Gaon

by Samuel Poznański