Attention‐network specific alterations of structural connectivity in the undamaged white matter in acute neglect

Visual neglect results from dysfunction within the spatial attention network. The structural connectivity in undamaged brain tissue in neglect has barely been investigated until now. In the present study, we explored the microstructural white matter characteristics of the contralesional hemisphere in relation to neglect severity and recovery in acute stroke patients. We compared age‐matched healthy subjects and three groups of acute stroke patients (9 ± 0.5 days after stroke): (i) patients with nonrecovered neglect (n = 12); (ii) patients with rapid recovery from initial neglect (within the first week post‐stroke, n = 7), (iii) stroke patients without neglect (n = 17). We analyzed the differences between groups in grey and white matter density and fractional anisotropy (FA) and used fiber tracking to identify the affected fibers. Patients with nonrecovered neglect differed from those with rapid recovery by FA‐reduction in the left inferior parietal lobe. Fibers passing through this region connect the left‐hemispheric analogues of the ventral attention system. Compared with healthy subjects, neglect patients with persisting neglect had FA‐reduction in the left superior parietal lobe, optic radiation, and left corpus callosum/cingulum. Fibers passing through these regions connect centers of the left dorsal attention system. FA‐reduction in the identified regions correlated with neglect severity. The study shows for the first time white matter changes within the spatial attention system remote from the lesion and correlating with the extent and persistence of neglect. The data support the concept of neglect as disintegration within the whole attention system and illustrate the dynamics of structural‐functional correlates in acute stroke. Hum Brain Mapp 35:4678–4692, 2014. © 2014 Wiley Periodicals, Inc .     

Indications requiring preoperative magnetic resonance imaging before knee arthroscopy

Introduction

Knee arthroscopy knee is gold standard in diagnosis and simultaneous treatment of knee disorders. But most patients undergo magnetic resonance imaging (MRI) before arthroscopy, although MRI results are not always consistent with arthroscopic findings. This raises the question in which suspected diagnoses MRI really has influence on diagnosis and consecutive surgical therapy.

Material and methods

Preoperative MRI of 330 patients with knee disorders were compared with arthroscopic findings. The MRI were performed by 23 radiologists without specialization in musculoskeletal diagnostics. Specificity, sensitivity, negative/positive predictive value and accuracy of MRI were calculated in comparison to arthroscopic findings.

Results

We found sensitivity/specificity of 58%/93% for anterior horn, 94%/46% for posterior horn of medial meniscus and 71%/81% for anterior and 62%/82% for posterior horn of lateral meniscus. Related to anterior cruciate ligament injuries we showed sensitivity/specificity of 82%/91% for grade 0 + I and 72%/96% for grade II + III. For Cartilage damage sensitivity/specificity of 98%/7% for grade I-, 89%/29% for grade II-, 96%/38% for grade III- and 96%/69% for grade IV-lesions were revealed.

Conclusions

The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres.The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres.     

Synthesis and phase behaviour of new carbazole containing liquid crystal side chain polysiloxanes

A series of chiral mesogenic side chain polymers containing a carbazole unit have been synthesized and investigated with regard to their liquid crystal (1c) phase behaviour. The carbazole units are linked either via the 2-position with a 1-oxycarbonyl-4-alkoxylphenyl moiety (end-on) or via the 9-position with an alkyl chain (side-on) to polymethylsiloxane. Only end-on polymers with long spacers or a ratio bigger one of spacer length and the free lateral alkyl chain length exhibit stable or metastable smectic phases. The side-on polymers are only isotropic or crystalline.