The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
John R Wingard - One of the best experts on this subject based on the ideXlab platform.
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tacrolimus fk506 induced Cerebral Blindness following bone marrow transplantation
Bone Marrow Transplantation, 1996Co-Authors: Steven M Devine, N J Newman, J L Siegel, G J Joseph, T C Geis, J A Schneider, R B Geller, John R WingardAbstract:Three patients who developed acute onset of Cerebral Blindness within 5-47 days of BMT using tacrolimus (FK506) as primary GVHD prophylaxis are described. This syndrome has been described with the use of cyclosporin A (CsA) and FK506 in solid organ transplant recipients. CsA-induced Cerebral Blindness has also been noted in BMT recipients but to date there have been no reports of this complication in BMT patients receiving FK506. We have noted a striking similarity in the clinical and radiographic presentations between these patients and those with CsA-associated Cerebral Blindness. Reversibility within 1-2 weeks of onset and the potential for substitution of CsA for FK506 in these patients is described.
D P Bergsma - One of the best experts on this subject based on the ideXlab platform.
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visual rehabilitation in chronic Cerebral Blindness a randomized controlled crossover study
Frontiers in Neurology, 2016Co-Authors: Joris A Elshout, D P Bergsma, Freekje Van Asten, Carel B Hoyng, Albert V Van Den BergAbstract:The treatment of patients suffering from Cerebral Blindness following stroke is a topic of much recent interest. Several types of treatment are under investigation such as substitution with prisms and compensation training of saccades. A third approach, aimed at vision restitution, is controversial as a proper controlled study design is missing. In the current study twenty-seven chronic stroke patients with homonymous visual field defects trained at home with a visual training device. We used a discrimination task for two types of stimuli: a static point stimulus and a new optic flow discontinuity stimulus. Using a randomized controlled crossover design, each patient received two successive training rounds, one with high contrast stimuli in their affected hemifield (test) and one round with low contrast stimuli in their intact hemifield (control). Goldmann and Humphrey perimetry were performed at the start of the study, and following each training round. In addition, reading performance was measured. Goldmann perimetry revealed a statistically significant reduction of the visual field defect after the test training, but not after the control training or after no intervention. For both training rounds combined, Humphrey perimetry revealed that the effect of a directed training (sensitivity change in trained hemifield) exceeded that of an undirected training (sensitivity change in untrained hemifield). The interaction between trained and tested hemifield was just above the threshold of significance (p=0.058). Interestingly, reduction of the field defect assessed by Goldmann perimetry increases with the difference between defect size as measured by Humphrey and Goldmann perimetry prior to training. Moreover, improvement of visual sensitivity measured by Humphrey perimetry increases with the fraction of non-responsive elements (i.e. more relative field loss) in Humphrey perimetry prior to training. Reading speed revealed a significant improvement after training. Our findings demonstrate that our training can result in reduction of the visual field. Improved reading performance after defect training further supports the significance of our training for improvement in daily life activities.
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Effects of Vision Restoration Training on Early Visual Cortex in Patients With Cerebral Blindness Investigated With Functional Magnetic Resonance Imaging
Journal of neurophysiology, 2010Co-Authors: Mathijs Raemaekers, D P Bergsma, R.j.a. Van Wezel, G. J. Van Der Wildt, A.v. Van Den BergAbstract:Cerebral Blindness is a loss of vision as a result of postchiasmatic damage to the visual pathways. Parts of the lost visual field can be restored through training. However, the neuronal mechanisms through which training effects occur are still unclear. We therefore assessed training-induced changes in brain function in eight patients with Cerebral Blindness. Visual fields were measured with perimetry and retinotopic maps were acquired with functional magnetic resonance imaging (fMRI) before and after vision restoration training. We assessed differences in hemodynamic responses between sessions that represented changes in amplitudes of neural responses and changes in receptive field locations and sizes. Perimetry results showed highly varied visual field recovery with shifts of the central visual field border ranging between 1 and 7°. fMRI results showed that, although retinotopic maps were mostly stable over sessions, there was a small shift of receptive field locations toward a higher eccentricity after training in addition to increases in receptive field sizes. In patients with bilateral brain activation, these effects were stronger in the affected than in the intact hemisphere. Changes in receptive field size and location could account for limited visual field recovery (±1°), although it could not account for the large increases in visual field size that were observed in some patients. Furthermore, the retinotopic maps strongly matched perimetry measurements before training. These results are taken to indicate that local visual field enlargements are caused by receptive field changes in early visual cortex, whereas large-scale improvement cannot be explained by this mechanism.
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visual training of Cerebral Blindness patients gradually enlarges the visual field
British Journal of Ophthalmology, 2010Co-Authors: D P Bergsma, G. J. Van Der WildtAbstract:Background: Multiple studies on recovery of hemianopsia after cerebrovascular accident report visual-field enlargements after stimulation of the visual-field border area. These enlargements are made evident by the difference between pre- and post-training measurements of the visual field. Until now, it was not known how the visual-field enlargement develops. Aim: To study how the enlargement develops as a function of time. Methods: 11 subjects were trained by stimulating the border area of their visual-field defect using a Goldmann perimeter. The visual-field border location was assessed using dynamic Goldmann perimetry before, after and during training (after each 10th training session). To monitor eye fixation, a video-based eye-tracker was used during each complete perimetry session. Results: It was found that visual-field enlargement during training is actually a gradual shift of the visual-field border, which was independent of the type of stimulus-set used during training. The shift could be observed while eye fixation was accurate. Conclusion: Visual-detection training leads to a decrease in detection thresholds in the affected visual-field areas and to visual-field enlargement. Training effects can be generalised to important daily-life activities like reading.
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gradual recovery from Cerebral Blindness during visual training
Proceedings of the Annual Meeting of the Cognitive Science Society, 2009Co-Authors: D P Bergsma, Gerjan Van Der WildtAbstract:Gradual Recovery from Cerebral Blindness during Visual Training Douwe Bergsma Utrecht University Gerjan Van der Wildt Utrecht University Abstract: Abstract: Several studies on recovery of hemianopsia after CVA report visual field enlargements after stimulation of the visual field border area. However, it is not known how the visual field enlargement develops as a function of time. We trained 11 subjects by stimulating their affected visual field. We assessed the border location with Goldmann perimetry before, during and after training. To exclude eye-movements as a cause of field enlargement, an eye-tracker was used during each complete perimetry session. We found that the visual field is enlarging gradually during training in the direction of the blind area, despite the fact that we did not only stimulated the shifting border area, but used a wide-ranged stimulus-set. Concluding, detection thresholds in stimulated areas in the affected field only start to decrease when the shifting field-border reaches those areas, resulting in a gradual visual field enlargement. Training effects can be generalized to important daily-life activities like reading.
Herbert G Vaughan - One of the best experts on this subject based on the ideXlab platform.
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flash and pattern reversal visual evoked potential abnormalities in infants and children with Cerebral Blindness
Developmental Medicine & Child Neurology, 2008Co-Authors: M Yitzchak D Frank, Diane Kurtzberg, A Judith M A Kreuzer, Herbert G VaughanAbstract:Visual evoked potentials (VEPs) were recorded of 60 infants and children with Cerebral Blindness, aged between six weeks and 10 years, and compared with age-matched normative data. Every patient had abnormal VEPs. 18 had absent flash and pattern VEPs and 13 had atypical or atypical and asymmetrical flash and pattern VEPs. Of the remaining 29, most had greater abnormality of pattern than of flash VEPs and greater abnormalities over parietal and temporal than occipital areas. Eight patients had normal occipital responses to flash and five others had delayed responses with normal morphology. One had normal occipital responses to pattern stimuli. All of these had abnormal late occipital responses or abnormal responses over the parietal and temporal areas. It is recommended that visual assessments using VEPs employ both flash and pattern stimuli, that pre-occipital as well as occipital recordings be made and that tracings be compared with age-specific normative data.
Steven M Devine - One of the best experts on this subject based on the ideXlab platform.
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tacrolimus fk506 induced Cerebral Blindness following bone marrow transplantation
Bone Marrow Transplantation, 1996Co-Authors: Steven M Devine, N J Newman, J L Siegel, G J Joseph, T C Geis, J A Schneider, R B Geller, John R WingardAbstract:Three patients who developed acute onset of Cerebral Blindness within 5-47 days of BMT using tacrolimus (FK506) as primary GVHD prophylaxis are described. This syndrome has been described with the use of cyclosporin A (CsA) and FK506 in solid organ transplant recipients. CsA-induced Cerebral Blindness has also been noted in BMT recipients but to date there have been no reports of this complication in BMT patients receiving FK506. We have noted a striking similarity in the clinical and radiographic presentations between these patients and those with CsA-associated Cerebral Blindness. Reversibility within 1-2 weeks of onset and the potential for substitution of CsA for FK506 in these patients is described.
A Hiraoka - One of the best experts on this subject based on the ideXlab platform.
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late onset cyclosporine induced Cerebral Blindness with abnormal spect imagings in a patient undergoing unrelated bone marrow transplantation
Bone Marrow Transplantation, 2000Co-Authors: N Uoshima, Takahiro Karasuno, Toshinari Yagi, S Kawamoto, T Hasegawa, Masato Yasumi, Masaki Murakami, H Teshima, Hiroyuki Nakamura, A HiraokaAbstract:A 23-year-old woman underwent HLA-matched unrelated BMT for CML. She developed Cerebral Blindness on day 81. Brain magnetic resonance imaging revealed hyperintensity on a T2-weighted image in the white and gray matter of the right frontal and both occipital lobes. Single-photon emission computed tomography (SPECT) was consistent with a decrease in radionuclide uptake in these areas, suggesting a vasoconstrictive mechanism. A diagnosis of CsA-induced encephalopathy was made and CsA was discontinued. Her vision recovered completely after 24 h and abnormal imaging resolved within 2 weeks. This case demonstrates late onset CsA-induced Cerebral Blindness with the previously unreported abnormalities on SPECT.