Developmental venous anomalies (DVAs) are considered variants of normal transmedullary veins. Their association with cavernous malformations is reported to increase the risk of hemorrhage. Expert ...consensus recommends meticulous planning with MR imaging, use of anatomical "safe zones", intraoperative monitoring of long tracts and cranial nerve nuclei, and preservation of the DVA as key to avoiding complications in brainstem cavernoma microsurgery. Symptomatic outflow restriction of DVA is rare, with the few reported cases in the literature restricted to DVAs in the supratentorial compartment.
We present a case report of the resection of a pontine cavernoma complicated by delayed outflow obstruction of the associated DVA. A female patient in her 20's presented with progressive left-sided hemisensory disturbance and mild hemiparesis. MRI revealed two pontine cavernomas associated with interconnected DVA and hematoma. The symptomatic cavernoma was resected
the infrafacial corridor. Despite the preservation of the DVA, the patient developed delayed deterioration secondary to venous hemorrhagic infarction. We discuss the imaging and surgical anatomy pertinent to brainstem cavernoma surgery, as well as the literature exploring the management of symptomatic infratentorial DVA occlusion.
Delayed symptomatic pontine venous congestive edema is extremely rare following cavernoma surgery. DVA outflow restriction from a post-operative cavity, intraoperative manipulation, and intrinsic hypercoagulability from COVID-10 infection are potential pathophysiological factors. Improved knowledge of DVAs, brainstem venous anatomy, and "safe entry zones" will further elucidate the etiology of and the efficacious treatment for this complication.
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•Gas flowrates in DED can significantly affect the build quality and track morphology.•Melt pool features affected include the width, depth, and deposited layer thickness.•Careful ...selection of gas parameters is essential to mitigate internal porosity.
Gas flow rates in Directed Energy Deposition (DED) Additive Manufacturing (AM) can significantly affect the quality of built parts by altering melt pool geometry. Using a DED process replicator and in situ synchrotron radiography, together with analogous experiments in an industrial DED machine, we investigate the impact of carrier gas and shield gas flow rates on build quality. The results reveal that there is a critical shield gas flow rate above which melt pools are flattened, tracks widen, and thus layer thickness decreases. The reduction in layer thickness is most prominent in conditions with low carrier gas flow rate, as the highly turbulent shield gas flow may divert slow moving powder particles away from the melt pool, decreasing capture efficiency. Very high flow rates increase internal porosity, as fast-moving particles impacting the melt pool surface can entrain chamber gas behind them. High gas flow rates also cool the melt pool, creating shallower melt pools with increased thermal gradients near the solidification front, increasing pore entrapment in the solidified track.
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•In-situ alloying of a Ti-1Al-8V-5Fe powder during Selective Laser Melting was investigated using synchrotron X-ray diffraction and infra-red thermal imaging.•The alloying process of ...a β-Ti powder was studied by X-ray diffraction and IR imaging.•Exothermic mixing aids in melting but this gives a mix of alloyed & unalloyed regions•A consistent microstructure is only achieved via thermal cycling in the HAZ
Blended Elemental powders are an emerging alternative to pre-alloyed powders in metal additive manufacturing due to the wider range of alloys producible with them and the cost savings from not developing novel feedstock. In this study, in situ alloying and concurrent microstructure evolution during SLM are investigated by performing SLM on a BE Ti-185 powder while tracking the surface temperatures via Infra-red imaging and phase transforma- tion via synchrotron X-ray Diffraction. We then performed post-mortem electron microscopy (Backscatter Electron imaging, Energy Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction) to further gain insight into microstructure development. We show that although exothermic mixing aids the melting process, laser melting results only in a mixture of alloyed and unmixed regions. Full alloying and thus a consistent microstructure is only achieved through further thermal cycling in the heat-affected zone.
Monoclonal antibodies have become a mainstay of treatment for many inflammatory diseases and malignancies. Multiple sclerosis is a chronic inflammatory, demyelinating, and neurodegenerative disease ...of the central nervous system and a common cause of disability in young adults. Ocrelizumab is a recombinant humanized monoclonal antibody that targets CD20-positive B cells and has been approved in the treatment of multiple sclerosis. Although considered safe, more than 30% of patients treated with Ocrelizumab developed infusion-related reactions, mostly regarded as mild. When severe, they can lead to a definite suspension of that drug. We present a case report of Ocrelizumab desensitization in a female patient who presented an immediate hypersensitivity reaction (urticaria and angioedema) during the first Ocrelizumab infusion. Although mechanisms involved in the response were not elucidated, the procedure occurred uneventfully and permitted first-line multiple sclerosis treatment maintenances. Desensitization should be considered a safe therapeutic option in patients with immediate hypersensitivity reactions to Ocrelizumab.
The skin constitutes a protective barrier to external physical and chemical aggressions. Although it is constantly exposed to various xenobiotics, it is generally considered poorly permeable to them, ...as for example metal ions, becoming unfortunately an entry route of such substances. Metals may penetrate inside the skin inducing more or less local effects such as skin sensitization and potential metals diffusion into the bloodstream. The objective of the study was to investigate the percutaneous penetration of metals in vitro - ex vivo in Franz cell with intact as well damaged skin applying a road dust powder. Moreover, porcine and human skins were compared. This study demonstrated that, after the application of a road dust powder on the skin, metals can penetrate and permeate this cutaneous membrane. From this experimental analysis, in intact skin lead (Pb) achieved the highest skin absorption in both human and porcine skin, while skin absorption profile of cobalt (Co) was the lowest in human skin than the one in porcine model. The concentrations of Ni present in receiving solution were higher compared to other metals in all experiments performed. The present work, definitely shows that metals permeation through damaged skin is accelerated than intact skin, as a result of the weaker cutaneous barrier function. According to published data, pig skin appeared as a suitable model for human skin. Our results confirmed that skin absorption of metals can be relevant in environmental exposures.
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•After the deposition of road dust powder on the skin, metals can penetrate this membrane inducing more or less local effects.•Metals permeation in damaged skin is accelerated than intact skin.•Exposure to road dust represents a potential health hazard, showing effects even at relatively lower dose.•Pig is a suitable experimental model for human skin.
The governing mechanistic behaviour of Directed Energy Deposition Additive Manufacturing (DED-AM) is revealed by a combined in situ and operando synchrotron X-ray imaging and diffraction study of a ...nickel-base superalloy, IN718. Using a unique DED-AM process replicator, real-space imaging enables quantification of the melt-pool boundary and flow dynamics during solidification. This imaging knowledge was also used to inform precise diffraction measurements of temporally resolved microstructural phases during transformation and stress development with a spatial resolution of 100 µm. The diffraction quantified thermal gradient enabled a dendritic solidification microstructure to be predicted and coupled to the stress state. The fast cooling rate entirely suppressed the formation of secondary phases or recrystallisation in the solid-state. Upon solidification, the stresses rapidly increase to the yield strength during cooling. This insight, combined with the large solidification range of IN718 suggests that the accumulated plasticity exhausts the ductility of the alloy, causing liquation cracking. This study has revealed the mechanisms that govern the formation of highly non-equilibrium microstructures during DED-AM.
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Abstract
In this work, the application of a time resolved multi-contrast beam tracking technique to the investigation of the melting and solidification process in metals is presented. The use of such ...a technique allows retrieval of three contrast channels, transmission, refraction and dark-field, with millisecond time resolution. We investigated different melting conditions to characterize, at a proof-of-concept level, the features visible in each of the contrast channels. We found that the phase contrast channel provides a superior visibility of the density variations, allowing the liquid metal pool to be clearly distinguished. Refraction and dark-field were found to highlight surface roughness formed during solidification. This work demonstrates that the availability of the additional contrast channels provided by multi-contrast X-ray imaging delivers additional information, also when imaging high atomic number specimens with a significant absorption.
A 27-year-old man presented with a two-year history of progressive ataxia. Family history was unremarkable. Examination revealed ataxia and alopecia. Serum Cortisol levels were low, suggesting ...adrenal insufficiency. Brain magnetic resonance imaging (MRI) disclosed cerebellar white matter involvement ((^Figure 1). Exome sequencing showed homozygous mutations (c.268del Glu90Argfs·13) in the ABCD1 gene and confirmed X-linked adrenol eukodystrophy (X-ALD).
Neuroimaging features in diethylene glycol poisoning Silva Júnior, Cilmário Leite da; Freitas, Leonardo Furtado; Pereira, Mariana Leite ...
Arquivos de Neuro-Psiquiatria,
07/2021, Letnik:
79, Številka:
7
Journal Article
Recenzirano
Odprti dostop
A 55-year-old man presented with acute onset vomiting, tetraplegia and ptosis, that progressed to renal failure and coma, four days after consuming beer. Several people that consumed that specific ...beer developed similar symptoms. Brain MRI showed restricted diffusion on cerebellum and thalamus. Beer analysis showed high levels of diethylene glycol. Patient died days later. Diethylene glycol is a substance commonly used in industrial products including antifreeze and coolant. Its toxicity causes severe metabolic acidosis, coma and multiorgan failure. Neurological toxicity is less well characterized, but brain MRI lesions may include cerebellar and thalamic abnormalities, with diffuse restriction.
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