Biomechanics of Pharyngeal Deglutitive Function Following Total Laryngectomy

Copyright © 2016 American Academy of Otolaryngology—Head and Neck Surgery Foundation. Reprinted by permission of SAGE PublicationsObjective: Post-laryngectomy surgery, pharyngeal weakness and pharyngoesophageal junction (PEJ) restriction are the underlying candidate mechanisms of dysphagia. We aimed to determine, in laryngectomees whether: 1) hypopharyngeal propulsion is reduced and/or PEJ resistance is increased; 2) endoscopic dilatation improves dysphagia; and 3) if so, whether symptomatic improvement correlate with reduction in resistance to flow across the PEJ. Methods: Swallow biomechanics were assessed in 30 total laryngectomees. Average peak contractile pressure (hPP) and hypopharyngeal intrabolus pressure (hIBP) were measured from combined high resolution manometry and video-fluoroscopic recordings of barium swallows (2, 5&10ml). Patients were stratified into severe dysphagia (Sydney Swallow Questionnaire (SSQ)>500) and mild/nil dysphagia (SSQ≤500). In 5 patients, all measurements were repeated after endoscopic dilatation. Results: Dysphagia was reported by 87%, and 57% had severe and 43% had minor/nil dysphagia. Laryngectomees had lower hPP than controls (110±14mmHg vs 170±15mmHg; p<0.05), while hIBP was higher (29±5mmHg vs 6±5mmHg; p<0.05). There were no differences in hPP between patient groups. However, hIBP was higher in severe than in mild/nil dysphagia (41±10mmHg vs 13±3mmHg; p<0.05). Pre-dilation hIBP (R2=0.97) and its decrement following dilatation (R2=0.98) were good predictors of symptomatic improvement. Conclusion: Increased PEJ resistance is the predominant determinant of dysphagia as it correlates better with dysphagia severity than peak pharyngal contractile pressure. While both baseline PEJ resistance and its decrement following dilatation are strong predictors of outcome following dilatation, the peak pharyngeal pressure is not. PEJ resistance is vital to detect as it is the only potentially reversible component of dysphagia in this context

What went wrong? The flawed concept of cerebrospinal venous insufficiency

In 2006, Zamboni reintroduced the concept that chronic impaired venous outflow of the central nervous system is associated with multiple sclerosis (MS), coining the term of chronic cerebrospinal venous insufficiency ('CCSVI'). The diagnosis of 'CCSVI' is based on sonographic criteria, which he found exclusively fulfilled in MS. The concept proposes that chronic venous outflow failure is associated with venous reflux and congestion and leads to iron deposition, thereby inducing neuroinflammation and degeneration. The revival of this concept has generated major interest in media and patient groups, mainly driven by the hope that endovascular treatment of 'CCSVI' could alleviate MS. Many investigators tried to replicate Zamboni's results with duplex sonography, magnetic resonance imaging, and catheter angiography. The data obtained here do generally not support the 'CCSVI' concept. Moreover, there are no methodologically adequate studies to prove or disprove beneficial effects of endovascular treatment in MS. This review not only gives a comprehensive overview of the methodological flaws and pathophysiologic implausibility of the 'CCSVI' concept, but also summarizes the multimodality diagnostic validation studies and open-label trials of endovascular treatment. In our view, there is currently no basis to diagnose or treat 'CCSVI' in the care of MS patients, outside of the setting of scientific research

Calculation of magnetic anisotropy energy in SmCo5

SmCo5 is an important hard magnetic material, due to its large magnetic anisotropy energy (MAE). We have studied the magnetic properties of SmCo5 using density functional theory (DFT) calculations where the Sm f-bands, which are difficult to include in DFT calculations, have been treated within the LDA+U formalism. The large MAE comes mostly from the Sm f-shell anisotropy, stemming from an interplay between the crystal field and the spin-orbit coupling. We found that both are of similar strengths, unlike some other Sm compounds, leading to a partial quenching of the orbital moment (f-states cannot be described as either pure lattice harmonics or pure complex harmonics), an optimal situation for enhanced MAE. A smaller portion of the MAE can be associated with the Co-d band anisotropy, related to the peak in the density of states at the Fermi energy. Our result for the MAE of SmCo5, 21.6 meV/f.u., agrees reasonably with the experimental value of 13-16 meV/f.u., and the calculated magnetic moment (including the orbital component) of 9.4 mu_B agrees with the experimental value of 8.9 mu_B.Comment: Submitted to Phys. Rev.

Static Critical Behavior of the Spin-Freezing Transition in the Geometrically Frustrated Pyrochlore Antiferromagnet Y2Mo2O7

Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a spin-freezing transition and magnetic irreversibilities below a temperature Tf similar to what is observed nonlinear magnetization measurements on Y2Mo2O7 that provide strong evidence that there is an underlying thermodynamic phase transition at Tf, which is characterized by critical exponents \gamma \approx 2.8 and \beta \approx 0.8. These values are typical of those found in random spin glasses, despite the fact that the level of random disorder in Y2Mo2O7 is immeasurably small.Comment: Latex file, calls for 4 encapsulated postscript figures (included). Submitted to Phys. Rev. Letters

Deterministic control of magnetic vortex wall chirality by electric field

Concepts for information storage and logical processing based on magnetic domain walls have great potential for implementation in future information and communications technologies. To date, the need to apply power hungry magnetic fields or heat dissipating spin polarized currents to manipulate magnetic domain walls has limited the development of such technologies. The possibility of controlling magnetic domain walls using voltages offers an energy efficient route to overcome these limitations. Here we show that a voltage-induced uniaxial strain induces reversible deterministic switching of the chirality of a magnetic vortex wall. We discuss how this functionality will be applicable to schemes for information storage and logical processing, making a significant step towards the practical implementation of magnetic domain walls in energy efficient computing

Universities and community-based research in developing countries: community voice and educational provision in rural Tanzania

The main focus of recent research on the community engagement role of universities has been in developed countries, generally in towns and cities and usually conducted from the perspectives of universities rather than the communities with which they engage. The purpose of this paper is to investigate the community engagement role of universities in the rural areas of developing countries, and its potential for strengthening the voice of rural communities. The particular focus is on the provision of primary and secondary education. The paper is based on the assumption that in order for community members to have both the capacity and the confidence to engage in political discourse for improving educational capacity and quality, they need the opportunity to become involved and well-versed in the options available, beyond their own experience. Particular attention is given in the paper to community-based research (CBR). CBR is explored from the perspectives of community members and local leaders in the government-community partnerships which have responsibility for the provision of primary and secondary education in rural Tanzania. The historical and policy background of the partnerships, together with findings from two case studies, provide the context for the paper

Inter- and intra-rater reliability of the Chicago Classification in pe-diatric high-resolution esophageal manometry recordings

This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving'.Copyright © 2015 John Wiley & Sons, Inc. All rights reserved.Background The Chicago Classification (CC) facilitates interpretation of high-resolution manometry (HRM) recordings. Application of this adult based algorithm to the pediatric population is unknown. We therefore assessed intra and interrater reliability of software-based CC diagnosis in a pediatric cohort. Methods Thirty pediatric solid state HRM recordings (13M; mean age 12.1 ± 5.1 years) assessing 10 liquid swallows per patient were analyzed twice by 11 raters (six experts, five non-experts). Software-placed anatomical landmarks required manual adjustment or removal. Integrated relaxation pressure (IRP4s), distal contractile integral (DCI), contractile front velocity (CFV), distal latency (DL) and break size (BS), and an overall CC diagnosis were software-generated. In addition, raters provided their subjective CC diagnosis. Reliability was calculated with Cohen's and Fleiss’ kappa (κ) and intraclass correlation coefficient (ICC). Key Results Intra- and interrater reliability of software-generated CC diagnosis after manual adjustment of landmarks was substantial (mean κ = 0.69 and 0.77 respectively) and moderate-substantial for subjective CC diagnosis (mean κ = 0.70 and 0.58 respectively). Reliability of both software-generated and subjective diagnosis of normal motility was high (κ = 0.81 and κ = 0.79). Intra- and interrater reliability were excellent for IRP4s, DCI, and BS. Experts had higher interrater reliability than non-experts for DL (ICC = 0.65 vs ICC = 0.36 respectively) and the software-generated diagnosis diffuse esophageal spasm (DES, κ = 0.64 vs κ = 0.30). Among experts, the reliability for the subjective diagnosis of achalasia and esophageal gastric junction outflow obstruction was moderate-substantial (κ = 0.45–0.82). Conclusions & Inferences Inter- and intrarater reliability of software-based CC diagnosis of pediatric HRM recordings was high overall. However, experience was a factor influencing the diagnosis of some motility disorders, particularly DES and achalasia