Long-term outcome of transobturator tape (TOT) for treatment of stress urinary incontinence in females with neuropathic bladders.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVES: Stress urinary incontinence (SUI) is a cause of significant distress in women with neurogenic bladder dysfunction (NBD) due to spinal cord injury (SCI). Transobturator tape (TOT) has not previously been studied in this select group for cure of SUI. We aim to determine the long-term safety and efficacy of TOT in SCI patients with NBD and SUI. SETTING: London, the United Kingdom. METHODS: All patients undergoing TOT between 2005 and 2013 were identified (27 patients). All patients had pre-operative videocystometrogram (VCMG) and all had VCMG-proven SUI. Mean follow-up was 5.2 years. Patient-reported leakage, satisfaction, change in bladder management, complications and de novo overactive bladder (OAB) were recorded. RESULTS: Mean age was 56 years (range 30-82) with complete follow-up. Twenty-two patients (81.5%) reported complete dryness from SUI post surgery. One patient (3.7%) reported SUI only when her bladder was very full but was satisfied. Twenty-three patients (85.2%) were happy. Four patients (14.8%) remained wet. Twenty-five patients (92.6%) had no change in bladder management. Two out of five patients (40%) who voided by straining prior to surgery required clean intermittent self-catheterisation (CISC) post-operatively. Two patients (7.4%) developed de novo OAB. No bladder or vaginal injuries, tape erosions or urethral obstruction were seen. Three patients (11.1%) had transient thigh pain. CONCLUSION: In women with NBD and SUI, TOT should be considered safe and effective with very good medium/long-term outcomes. There may be an increased risk of CISC in women who void by straining pre-operatively.

Long-term urological management in spinal injury units in the U.K. and Eire: a follow-up study.

AIMS: The majority of patients with spinal cord injury (SCI) will develop neurogenic lower urinary tract dysfunction (NLUTD). These patients require a long-term urological follow-up. The follow-up protocol has varied across SCI units in the United Kingdom and Eire. We reviewed the long-term management in the SCI units to identify changes in practice over a decade and compared them to current guidelines. METHODS: We present results of a review of all SCI centres in the United Kingdom and Eire on their long-term urological management before and after the current guidelines and compared the results with European Association of Urology (EAU) Guidelines on NLUTD and the proposed British guidelines for the urological management of patients with SCI. Data were collected through questionnaires posted to SCI units. RESULTS: SCI patients are followed up in outpatients annually in the SCI centres and the frequency of follow-up remains largely unchanged. More SCI units perform renal tract imaging annually as a part of SCI follow-up. Most units follow the proposed British guideline indications for urodynamics and do not perform 'routine urodynamics'. CONCLUSIONS: We conclude that the long-term management of SCI patients in SCI units in the United Kingdom and Eire has changed overtime to follow the proposed British guidelines. EAU guidelines offer a more extensive follow-up regime. Last, there is a continued lack of high-quality evidence to support an optimal long-term follow-up protocol. Importantly, there is a lack of evidence on clinical outcomes when these guidelines have been followed.

Order of phase transitions in barrier crossing.

A spatially extended classical system with metastable states subject to weak spatiotemporal noise can exhibit a transition in its activation behavior when one or more external parameters are varied. Depending on the potential, the transition can be first or second order, but there exists no systematic theory of the relation between the order of the transition and the shape of the potential barrier. In this paper, we address that question in detail for a general class of systems whose order parameter is describable by a classical field that can vary in both space and time, and whose zero-noise dynamics are governed by a smooth polynomial potential. We show that a quartic potential barrier can have only second-order transitions, confirming an earlier conjecture [D. L. Stein, J. Stat. Phys. 114, 1537 (2004)]. We then derive, through a combination of analytical and numerical arguments, both necessary and sufficient conditions to have a first-order vs a second-order transition in noise-induced activation behavior, for a large class of systems with smooth polynomial potentials of arbitrary order. We find in particular that the order of the transition is especially sensitive to the potential behavior near the top of the barrier.

Front propagation into unstable metal nanowires.

Long, cylindrical metal nanowires have recently been observed to form and be stable for seconds at a time at room temperature. Their stability and structural dynamics is well described by a continuum model, the nanoscale free-electron model, which predicts cylinders in certain intervals of radius to be linearly unstable. In this paper, I study how a small, localized perturbation of such an unstable wire grows exponentially and propagates along the wire with a well-defined front. The front is found to be pulled and forms a coherent pattern behind it. It is well described by a linear marginal stability analysis of front propagation into an unstable state. In some cases, nonlinearities of the wire dynamics are found to trigger an invasive mode that pushes the front. Experimental procedures that could lead to the observation of this phenomenon are suggested.

Electronic and atomic shell structure in aluminium nanowires.

We report experiments on aluminium nanowires in ultra-high vacuum at room temperature that reveal a periodic spectrum of exceptionally stable structures. Two 'magic' series of stable structures are observed: at low conductance, the formation of stable nanowires is governed by electronic shell effects whereas for larger contacts atomic packing dominates. The crossover between the two regimes is found to be smooth. A detailed comparison of the experimental results to a theoretical stability analysis indicates that, while the main features of the observed electron-shell structure are similar to those of alkali and noble metals, a sequence of extremely stable wires plays a unique role in aluminium. This series appears isolated in conductance histograms and can be attributed to 'superdeformed' non-axisymmetric nanowires.

Theory of metastability in simple metal nanowires.

Thermally induced conductance jumps of metal nanowires are modeled using stochastic Ginzburg-Landau field theories. Changes in radius are predicted to occur via the nucleation of surface kinks at the wire ends, consistent with recent electron microscopy studies. The activation rate displays nontrivial dependence on nanowire length, and undergoes first- or second-order-like transitions as a function of length. The activation barriers of the most stable structures are predicted to be universal, i.e., independent of the radius of the wire, and proportional to the square root of the surface tension. The reduction of the activation barrier under strain is also determined.

Jahn-Teller distortions and the supershell effect in metal nanowires.

A stability analysis of metal nanowires shows that a Jahn-Teller deformation breaking cylindrical symmetry can be energetically favorable, leading to stable nanowires with elliptic cross sections. The sequence of stable cylindrical and elliptical nanowires allows for a consistent interpretation of experimental conductance histograms for alkali metals, including both the electronic shell and supershell structures. It is predicted that for gold, elliptical nanowires are even more likely to form since their eccentricity is smaller than for alkali metals. The existence of certain metastable superdeformed nanowires is also predicted.

Quantum necking in stressed metallic nanowires.

When a macroscopic metallic wire is subject to tensile stress, it necks down smoothly as it elongates. We show that nanowires with radii comparable to the Fermi wavelength display remarkably different behavior. Using concepts from fluid dynamics, a partial differential equation for nanowire shape evolution is derived from a semiclassical energy functional that includes electron-shell effects. A rich dynamics involving movement and interaction of kinks connecting locally stable radii is found, and a new class of universal equilibrium shapes is predicted.