Successful microvascular decompression surgery for dolichoectatic vertebral artery compression of medulla oblongata in a patient with hypersomnia disorder

Introduction: Hypersomnia is a condition in which a person has trouble staying awake during the day. There are several potential causes of it, including sleep apnea and sleep disorders. Case presentation: A 43 year old male was referred to our practice with complaints of hypersomnia, snoring, slurred speech and sleep apnea for more diagnostic and therapeutic interventions. His brain MRI was significant for a vascular loop compression on medulla oblongata. The patient underwent microvascular decompression surgery subsequently and showed improvement in all of his symptoms. Conclusion: One of the rare causes of sleep apnea is medulla oblongata compression by a vascular loop. Vertebrobasilar dolichoectasia may cause this phenomenon probably and should be reviewed in imaging examinations more precisely. Microvascular decompression by using a synthetic Teflon patch may be helpful in management of these patients. © 2019, © 2019 The Neurosurgical Foundation

Cervical Lipomyelomeningocele Presenting with Progressive Motor Deficit: A Case Report and Review of the Literature

Cervical lipomyelomeningocele is a very rare form of spina bifida occulta, which can cause some complications following tethered cord syndrome. We report a 10-year-old female with a history of progressive upper-extremity weakness, a very small soft-tissue mass at the posterior aspect of her neck, and evidence of lipomyelomeningocele in her radiological study. The patient underwent laminectomy of C6 and C7 together with resection of lipomatous tissue attaching to the cord from superficial tissue and cord untethering, which resulted in progressive improvement of her weakness. © 2019 © 2019 S. Karger AG, Basel. Copyright: All rights reserved

Studying the effects of elongational properties on atomization of weakly viscoelastic solutions using Rayleigh Ohnesorge Jetting Extensional Rheometry (ROJER)

The extensional rheological properties of dilute polymer solutions play a dominant role in many commercial processes such as air-assisted atomization. This is a high deformation rate process important in application of diverse materials such as paints, fertilizer sprays and delivery of airborne drugs. Dilute polymeric solutions which have identical values of high shear-rate viscosity (HSV) often exhibit different values of Sauter Mean Diameter (SMD) in their spray size distributions as a result of differing extensional rheological properties. We explore the atomization of a series of model Poly(ethylene oxide) (PEO) solutions dissolved in water/glycerol mixtures. Each solution is sprayed with an air-assisted spray gun under similar conditions and imaged with a commercial spray measurement system. The values of HSV for PEO solutions are close to the solvent viscosity and matched to those of typical ink or paint samples. The surface tensions of the fluids are also tuned to be very similar, however both the SMD and the droplet size distribution change considerably. For the highest molecular weight PEO systems, interconnected beads-on-string structures are observed at different positions of the spray fan. Capillary Break-up Extensional Rheometry (CaBER) can be used to measure the extensional properties of the more viscous solutions, but the well-known limitations of this approach include inertially-induced asymmetries, gravitational sagging and the very short filament lifetimes of low viscosity samples all of which constrain the range of relaxation times that can be probed. Consequently we also explore the use of Rayleigh Ohnesorge Jet Elongational Rheometry (ROJER) to probe the extensional response of these viscoelastic solutions at realistic timescales and deformation rates. A cylindrical liquid jet is excited by a piezo-actuator at a known frequency as it exits a micromachined nozzle, and stroboscopic imaging provides high temporal and spatial resolution in the break-up process. Analyzing the evolution in the jet diameter before break-up enables meaningful measurement of relaxation times down to values as small as 60 μs, and these values can be directly correlated with the differences in the final spray size distributions and the mean diameters. We outline a simple model for the fluid dynamics of the thinning filaments close to breakup that accurately describes the variation of the average droplet diameter as a function of the elongational relaxation time measured for each fluid