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Kollewe K.,Hannover Medical School | Korner S.,Hannover Medical School | Dengler R.,Hannover Medical School | Petri S.,Hannover Medical School | Mohammadi B.,International Neuroscience Institute INI
Neurology Research International | Year: 2012

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disorder which is incurable to date. As there are many ongoing studies with therapeutic candidates, it is of major interest to develop biomarkers not only to facilitate early diagnosis but also as a monitoring tool to predict disease progression and to enable correct randomization of patients in clinical trials. Magnetic resonance imaging (MRI) has made substantial progress over the last three decades and is a practical, noninvasive method to gain insights into the pathology of the disease. Disease-specific MRI changes therefore represent potential biomarkers for ALS. In this paper we give an overview of structural and functional MRI alterations in ALS with the focus on task-free resting-state investigations to detect cortical network failures. © 2012 Katja Kollewe et al. Source


Pujol S.,Harvard University | Wells W.,Harvard University | Pierpaoli C.,U.S. National Institutes of Health | Brun C.,University of Pennsylvania | And 25 more authors.
Journal of Neuroimaging | Year: 2015

Diffusion tensor imaging (DTI) tractography reconstruction of white matter pathways can help guide brain tumor resection. However, DTI tracts are complex mathematical objects and the validity of tractography-derived information in clinical settings has yet to be fully established. To address this issue, we initiated the DTI Challenge, an international working group of clinicians and scientists whose goal was to provide standardized evaluation of tractography methods for neurosurgery. The purpose of this empirical study was to evaluate different tractography techniques in the first DTI Challenge workshop. Eight international teams from leading institutions reconstructed the pyramidal tract in four neurosurgical cases presenting with a glioma near the motor cortex. Tractography methods included deterministic, probabilistic, filtered, and global approaches. Standardized evaluation of the tracts consisted in the qualitative review of the pyramidal pathways by a panel of neurosurgeons and DTI experts and the quantitative evaluation of the degree of agreement among methods. RESULTS: The evaluation of tractography reconstructions showed a great interalgorithm variability. Although most methods found projections of the pyramidal tract from the medial portion of the motor strip, only a few algorithms could trace the lateral projections from the hand, face, and tongue area. In addition, the structure of disagreement among methods was similar across hemispheres despite the anatomical distortions caused by pathological tissues. The DTI Challenge provides a benchmark for the standardized evaluation of tractography methods on neurosurgical data. This study suggests that there are still limitations to the clinical use of tractography for neurosurgical decision making. © 2015 by the American Society of Neuroimaging. Source


Amengual J.L.,University of Barcelona | Valero-Cabre A.,University Pierre and Marie Curie | Valero-Cabre A.,Boston University | Valero-Cabre A.,University of Barcelona | And 17 more authors.
BMC Neurology | Year: 2012

Background: We report the case of a chronic stroke patient (62 months after injury) showing total absence of motor activity evoked by transcranial magnetic stimulation (TMS) of spared regions of the left motor cortex, but near-to-complete recovery of motor abilities in the affected hand.Case presentation: Multimodal investigations included detailed TMS based motor mapping, motor evoked potentials (MEP), and Cortical Silent period (CSP) as well as functional magnetic resonance imaging (fMRI) of motor activity, MRI based lesion analysis and Diffusion Tensor Imaging (DTI) Tractography of corticospinal tract (CST). Anatomical analysis revealed a left hemisphere subinsular lesion interrupting the descending left CST at the level of the internal capsule. The absence of MEPs after intense TMS pulses to the ipsilesional M1, and the reversible suppression of ongoing electromyographic (EMG) activity (indexed by CSP) demonstrate a weak modulation of subcortical systems by the ipsilesional left frontal cortex, but an inability to induce efficient descending volleys from those cortical locations to right hand and forearm muscles. Functional MRI recordings under grasping and finger tapping patterns involving the affected hand showed slight signs of subcortical recruitment, as compared to the unaffected hand and hemisphere, as well as the expected cortical activations.Conclusions: The potential sources of motor voluntary activity for the affected hand in absence of MEPs are discussed. We conclude that multimodal analysis may contribute to a more accurate prognosis of stroke patients. © 2012 Amengual et al.; licensee BioMed Central Ltd. Source


Kollewe K.,Hannover Medical School | Mohammadi B.,University of Lubeck | Mohammadi B.,International Neuroscience Institute INI | Kohler S.,Hannover Medical School | And 3 more authors.
Journal of Neural Transmission | Year: 2015

Botulinum toxin (BT) therapy is the treatment of choice for blepharospasm (BPS). Currently available BT type A drugs include Botox®, Dysport® and Xeomin®. Until now, there are few long-term studies on BT therapy for BPS. This is the first long-term study comparing all three major BT drugs. We collected treatment, efficacy and adverse effect data on BPS patients treated with either Botox®, Dysport® or Xeomin® for at least eight consecutive treatments. Two hundred and eighty-eight patients (208 females, 80 males, age 62 ± 12 years) were included in this study. The treatment time was 11.2 ± 4.1 years covering 10,701 injection series. Doses were 47 ± 10 MU for Botox®, 120 ± 35 MU for Dysport® and 62 ± 11 MU for Xeomin® (Botox® dose vs Xeomin® dose: p < 0.001, unpaired t test). 85 % of all patients had stable doses. The onset of the therapeutic effect was after 6.1 ± 3.3 days and its duration lasted 10.2 ± 3.5 weeks. The Global Clinical Improvement (GCI, 0 = no, 1 = slight, 2 = moderate, 3 = marked improvement in severity and function) as estimated by the patient was 2.5 ± 0.6. It was stable in 90 % of the patients. Adverse effect frequency was 3.0 % (ptosis 2.3 %, dry eye 0.5 %, diplopia 0.2 %). None of these findings was significantly different between Botox®, Dysport® and Xeomin®. Our study, one of the largest studies on BT therapy of BPS and the study with the longest follow-up, confirms that BT therapy produces robust clinical improvement which is stable throughout the treatment time. Therapeutic effects start after 6.1 days and last for about 10 weeks before they start to vanish. With this, they are approximately 2 weeks shorter than the recommended inter-injection interval. Adverse effects were rare, mild and always transient. BT therapy is a safe and effective treatment for BSP. Shorter inter-injection intervals may improve therapeutic results. © 2014, Springer-Verlag Wien. Source


Mohammadi B.,University of Lubeck | Mohammadi B.,International Neuroscience Institute INI | Kollewe K.,Hannover Medical School | Samii A.,International Neuroscience Institute INI | And 5 more authors.
Human Brain Mapping | Year: 2012

Objectives:: Writer's cramp (WC) is characterized by excessive cocontractions of agonist and antagonist hand and forearm muscles during writing. Changes in functional magnetic resonance imaging activation patterns in such conditions can be ambiguous as they might either reflect some aspect of the primary pathophysiological mechanism or, alternatively, may be the result of adaptive actions during task execution. To circumvent this problem, we examined WC patients during rest, i.e., without a task, using independent component analysis (ICA) applied to the blood oxygen level-dependent time series. Methods:: Functionally connected brain networks during rest were defined by ICA to assess differences between WC patients (n = 16) and healthy controls (n = 16). Analysis was carried out using FMRIB's Software Library. Results:: Two functional networks showed between-group differences, the sensorimotor network and the default-mode network. In WC patients, the connectivity was reduced in the left postcentral area and increased in basal ganglia in contrast to healthy controls. These changes were not reversed after treatment with botulinum toxin. Conclusions:: In line with other studies, the results show a dysfunction in cortico-subcortical circuits in WC involving somatosensory cortex, areas interfacing the sensory and motor systems, and putamen contralateral to symptomatic hand. © 2011 Wiley Periodicals, Inc. Source

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