Perfusion computed tomography in prediction of functional outcome in patients with acute ischaemic stroke

PURPOSE: To determine the value of perfusion computed tomography (CT) in prediction of the clinical course and late functional outcome in patients with acute ischaemic stroke who had unremarkable initial brain CT examination. MATERIAL AND METHODS: Single slice perfusion CT was performed in 55 consecutive patients (27 women, mean age 67 &#177; &#177; 11 years) with acute ischaemic stroke within 6 hours (median 2.26 hours) from onset of symptoms. Values of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) obtained from affected hemisphere were compared to respective values in non-affected hemisphere (relative parameters). Initial neurological deficits were estimated using NIH Stroke Scale (NIHSS) score and correlated with perfusion CT values, employing Spearman rank correlation coefficient (r). Values of perfusion CT parameters in prediction of functional outcome were determined by comparing against scores on modified Rankin Scale (mRS) and Glasgow Outcome Scale (GOS) after three months of onset of stroke. RESULTS: All perfusion CT parameters significantly correlated with initial neurological deficit. The highest correlation with the NIHSS was found for relative CBF, which correlated better than absolute CBF (rCBF r = 0.69; CBF r = 0.50, P < 0.001). In prediction of favourable outcome (mRS &#8804; 2) the commonly employed thresholds (in parentheses) and associated sensitivity, specificity, positive and negative predictive values were: 87%, 44%, 79%, and 58% for CBF (10 ml/min/100 g), 59%, 81%, 88%, and 49% for rCBF (48%), 49%, 56%, 73%, and 31% for CBV (2 ml/100 g), 87%, 44%, 79% and 58% for rCBV (60%), 41%, 81%, 84% and 36% for MTT (6 s) and 54%, 81%, 87% and 49% for rMTT (145%), respectively, while for prediction of excellent outcome (mRS &#8804; 1), the only statistically significant respective accuracy measures were for rCBV, 90%, 35%, 60%, 75%, and for rCBF, 62%, 69%, 69% and 62%. CONCLUSIONS: In patients within the first 6 hours from stroke onset, and without a hypodensity sign on initial routine CT examination, perfusion CT provides quantitative parameters that correlate well with initial neurological status and late functional outcome

Do Spinors Frame-Drag?

We investigate the effect of the intrinsic spin of a fundamental spinor field on the surrounding spacetime geometry. We show that despite the lack of a rotating stress-energy source (and despite claims to the contrary) the intrinsic spin of a spin-half fermion gives rise to a frame-dragging effect analogous to that of orbital angular momentum, even in Einstein-Hilbert gravity where torsion is constrained to be zero. This resolves a paradox regarding the counter-force needed to restore Newton's third law in the well known spin-orbit interaction. In addition, the frame-dragging effect gives rise to a {\it long-range} gravitationally mediated spin-spin dipole interaction coupling the {\it internal} spins of two sources. We argue that despite the weakness of the interaction, the spin-spin interaction will dominate over the ordinary inverse square Newtonian interaction in any process of sufficiently high-energy for quantum field theoretical effects to be non-negligible.Comment: V2: published version, mostly minor clarifications from V

Hemikraniektomia odbarczająca w udarze niedokrwiennym mózgu

Background and purpose Hemispheric ischaemic stroke complicated by oedema is associated with high mortality. The results of randomized studies showed that decompressive hemicraniectomy performed in this group of patients could be beneficial. First experiences with implementation of hemicraniectomy in patients with brain infarct in our stroke centre are presented. Material and methods Between August 2007 and July 2008, four patients with hemispheric brain infarcts complicated by malignant oedema underwent decompressive hemicraniectomy within 72 hours from symptoms onset. Stroke severity was assessed with the National Institutes of Health Stroke Scale (NIHSS). Clinical outcome was assessed 3, 6 and 12 months after the event using the modified Rankin scale (mRS). Results In the first patient, the neurosurgical procedure included only decompressive hemicraniectomy, whereas in the other three duraplasty was performed additionally. The first patient died 23 days after the stroke onset due to acute respiratory failure. Another died at four months after the event, due to infectious complications. The remaining two patients presented severe functional disability 12 months after the procedure (mRS score 4). Conclusions Decompressive surgery with duraplasty can be a life-saving procedure for patients with brain oedema. To our knowledge, the presented cases are among the first reported cases of hemispheric ischaemic stroke treated with decompressive hemicraniectomy in Poland. Extended follow-up with a larger group of patients is necessary to assess long-term outcome.Wstęp i cel pracy Półkulowy udar niedokrwienny mózgu powikłany obrzękiem mózgu obarczony jest dużą ś miertelnością. Wyniki badań z randomizacją wskazują na skuteczność kraniektomii odbarczającej w tej grupie chorych. W pracy przedstawiono pierwsze doświadczenia z zastosowania kraniektomii odbarczającej u chorych z udarem niedokrwiennym mózgu leczonych w Klinice Neurologii Wieku Podeszłego ŚUM w Katowicach. Materiał i metody W okresie od sierpnia 2007 r. do lipca 2008 r. u 4 chorych z półkulowym udarem niedokrwiennym mózgu powikłanym obrzękiem mózgu przeprowadzono zabieg kraniektomii odbarczającej maksymalnie do 72 godz. od wystąpienia objawów udaru. Stan neurologiczny chorych oceniono, stosując skalę National Institutes of Health Stroke Scale (NIHSS). Oceny stanu funkcjonalnego dokonano przy użyciu zmodyfikowanej skali Rankina w 3., 6. i 12. miesiącu po udarze. Wyniki U pierwszego chorego wykonano jedynie kraniektomię odbarczającą, a u kolejnych 3 dodatkowo plastykę opony twardej. Pierwszy z pacjentów zmarł w 23. dobie od wystąpienia udaru w wyniku niewydolności oddechowej, kolejny w 4. miesiącu z powodu powikłań infekcyjnych. U pozostałych dwóch pacjentów w 12. miesiącu od udaru utrzymywał się duży stopień niesprawności (4 stopień w skali Rankina). Wnioski Kraniektomia odbarczająca może być zabiegiem ratującym życie chorych z obrzękiem mózgu. Przedstawione przypadki są jednymi z pierwszych w Polsce opisanymi przy-padkami zastosowania hemikraniektomii odbarczającej u chorych z półkulowym udarem niedokrwiennym. Konieczna jest dłuższa obserwacja większej grupy chorych, aby ocenić odległe efekty leczenia

On the extension of the concept of Thin Shells to The Einstein-Cartan Theory

This paper develops a theory of thin shells within the context of the Einstein-Cartan theory by extending the known formalism of general relativity. In order to perform such an extension, we require the general non symmetric stress-energy tensor to be conserved leading, as Cartan pointed out himself, to a strong constraint relating curvature and torsion of spacetime. When we restrict ourselves to the class of space-times satisfying this constraint, we are able to properly describe thin shells and derive the general expression of surface stress-energy tensor both in its four-dimensional and in its three-dimensional intrinsic form. We finally derive a general family of static solutions of the Einstein-Cartan theory exhibiting a natural family of null hypersurfaces and use it to apply our formalism to the construction of a null shell of matter.Comment: Latex, 21 pages, 1 combined Latex/Postscript figure; Accepted for publication in Classical and Quantum Gravit

Negative Energy Densities in Extended Sources Generating Closed Timelike Curves in General Relativity with and without Torsion

Near a spinning point particle in (2+1)-dimensional gravity (or near an infinitely thin, straight, spinning string in 3+1 dimensions) there is a region of space-time with closed timelike curves. Exact solutions for extended sources with apparently physically acceptable energy-momentum tensors, have produced the same exterior space-time structure. Here it is pointed out that in the case with torsion, closed timelike curves appear only for spin densities so high that the spin energy density is higher than the net effective energy density. In models without torsion, the presence of closed time-like curves is related to a heat flow of unphysical magnitude. This corroborates earlier arguments against the possibility of closed timelike curves in space-time geometries generated by physical sources.Comment: (to be published in Phys. Rev. D), 5 pages, REVTEX 3.0, NORDITA 93/62 A (Sept. 10/Revised Nov. 1, 1993

Multiple sclerosis: oral health, behaviours and limitations of daily oral hygiene — a questionnaire study

Clinical rationale for the study. Neurological deficits and progressing disability in patients with multiple sclerosis (MS) may hamper daily oral hygiene, but their relations with oral problems have not yet been clearly determined.Aim of the study. The aim of this study was to identify the most significant dental problems and limitations of daily oral hygiene in Polish patients with MS.Material and methods. 199 patients with diagnosed MS (median age 37 years) treated in the neurological outpatient clinic were interviewed using a paper-based questionnaire. They provided answers on oral health, behaviours and the limitations of their daily oral hygiene. Clinical information regarding symptoms, MS phenotype, relapses, medication and degrees of disability was based on medical records.Results. The most frequent symptoms were dry mouth (43.2%) and bleeding from gums (28.1%). Dry mouth was more frequent in patients with secondary-progressive MS (SPMS) than relapsing-remitting MS (65.4% vs 41.3%, p = 0.023). Patients with bleeding from gums had had MS for a longer duration (median 6 vs 4 years, p = 0.002). Difficulties in daily oral hygiene were more frequent in patients with SPMS (24.0% vs 8.1%; p = 0.016). Greater proportions of patients with muscle weakness of limbs, imbalance or pain brushed their teeth irregularly. Frequent (i.e. at least every six months) visits to the dentist’s surgery were uncommon in patients with SPMS (12.0% vs 39.7%, p = 0.010).Conclusions and clinical implications. Dry mouth and bleeding from gums are more frequent in patients with longer lasting and more advanced types of MS. Daily oral hygiene and oral health self-control is limited in patients with MS, mainly due to motor deficits, balance problems and pain, and this becomes worse with disease duration. To minimise the burden of the disease, patients with MS require better education and improvement in their awareness regarding proper oral health control, such as the use of electric toothbrushes. In addition, patients with chronic and progressive disability from multiple sclerosis may benefit from better organised access to dental care

Gravitational field around a screwed superconducting cosmic string in scalar-tensor theories

We obtain the solution that corresponds to a screwed superconducting cosmic string (SSCS) in the framework of a general scalar-tensor theory including torsion. We investigate the metric of the SSCS in Brans-Dicke theory with torsion and analyze the case without torsion. We show that in the case with torsion the space-time background presents other properties different from that in which torsion is absent. When the spin vanish, this torsion is a $\phi$-gradient and then it propagates outside of the string. We investigate the effect of torsion on the gravitational force and on the geodesics of a test-particle moving around the SSCS. The accretion of matter by wakes formation when a SSCS moves with speed $v$ is investigated. We compare our results with those obtained for cosmic strings in the framework of scalar-tensor theory.Comment: 22 pages, LaTeX, presented at the "XXII - Encontro Nacional de Fisica de Particulas e Campos", Sao Lourenco, MG, Brazi

Volterra Distortions, Spinning Strings, and Cosmic Defects

Cosmic strings, as topological spacetime defects, show striking resemblance to defects in solid continua: distortions, which can be classified into disclinations and dislocations, are line-like defects characterized by a delta function-valued curvature and torsion distribution giving rise to rotational and translational holonomy. We exploit this analogy and investigate how distortions can be adapted in a systematic manner from solid state systems to Einstein-Cartan gravity. As distortions are efficiently described within the framework of a SO(3) {\rlap{\supset}\times}} T(3) gauge theory of solid continua with line defects, we are led in a straightforward way to a Poincar\'e gauge approach to gravity which is a natural framework for introducing the notion of distorted spacetimes. Constructing all ten possible distorted spacetimes, we recover, inter alia, the well-known exterior spacetime of a spin-polarized cosmic string as a special case of such a geometry. In a second step, we search for matter distributions which, in Einstein-Cartan gravity, act as sources of distorted spacetimes. The resulting solutions, appropriately matched to the distorted vacua, are cylindrically symmetric and are interpreted as spin-polarized cosmic strings and cosmic dislocations.Comment: 24 pages, LaTeX, 9 eps figures; remarks on energy conditions added, discussion extended, version to be published in Class. Quantum Gra

Gravitational Phase Operator and Cosmic Strings

A quantum equivalence principle is formulated by means of a gravitational phase operator which is an element of the Poincare group. This is applied to the spinning cosmic string which suggests that it may (but not necessarily) contain gravitational torsion. A new exact solution of the Einstein- Cartan-Sciama-Kibble equations for the gravitational field with torsion is obtained everywhere for a cosmic string with uniform energy density, spin density and flux. A novel effect due to the quantized gravitational field of the cosmic string on the wave function of a particle outside the string is used to argue that spacetime points are not meaningful in quantum gravity.Comment: 22 pages, to be published Phys. Rev. D. Some minor changes have been made and a reference has been added to the paper of D.V. Gal'tsov and P.S. Letelier, Phys. Rev. D 47 (1993) 4273, which first contained the metric (2.2) external to the cosmic string. The present paper extends this solution to a regular solution inside the string as wel

Gravitational field around a time-like current-carrying screwed cosmic string in scalar-tensor theories

In this paper we obtain the space-time generated by a time-like current-carrying superconducting screwed cosmic string(TCSCS). This gravitational field is obtained in a modified scalar-tensor theory in the sense that torsion is taken into account. We show that this solution is comptible with a torsion field generated by the scalar field $\phi$. The analysis of gravitational effects of a TCSCS shows up that the torsion effects that appear in the physical frame of Jordan-Fierz can be described in a geometric form given by contorsion term plus a symmetric part which contains the scalar gradient. As an important application of this solution, we consider the linear perturbation method developed by Zel'dovich, investigate the accretion of cold dark matter due to the formation of wakes when a TCSCS moves with speed $v$ and discuss the role played by torsion. Our results are compared with those obtained for cosmic strings in the framework of scalar-tensor theories without taking torsion into account.Comment: 21 pages, no figures, Revised Version, presented at the "XXIV- Encontro Nacional de Fisica de Particulas e Campos ", Caxambu, MG, Brazil, to appear in Phys. Rev.