Towards viscoelastic characterisation of the human ulnar nerve: An early assessment using embalmed cadavers.

Cubital tunnel syndrome is the most prevalent neuropathy of the ulnar nerve and its aetiology is controversial. Potential replacement materials should display similar viscoelastic properties. The purpose of this study was to assess the feasibility and merit of quantifying the frequency-dependent viscoelastic properties of proximal and distal sections of the human ulnar nerve. Four ulnar nerves (n = 4) were dissected from the elbows of human cadavers and sectioned at the level of the cubital tunnel into proximal and distal sections. These eight sections of the ulnar nerve were sinusoidally loaded to induce stresses between 0.05 and 0.27 MPa and the viscoelastic properties were measured between 0.5 and 24 Hz using dynamic mechanical analysis. The nerves were found to exhibit frequency-dependent viscoelastic behaviour throughout this frequency range. The median storage moduli of the proximal nerves ranged between 7.03 and 8.18 MPa, and 8.85-10.19 MPa for distal nerves, over the frequency-sweep tested. The median loss moduli of the proximal nerves ranged between 0.46 and 0.81 MPa and between 0.51 and 0.80 MPa for distal nerves. Ulnar nerves display frequency dependency viscoelasticity. Such characterisation is feasible with potential applications to suitable nerve grafts.

Continence and micturition: an anatomical basis.

Urinary incontinence remains an important clinical problem worldwide, having a significant socio-economic, psychological, and medical burden. Maintaining urinary continence and coordinating micturition are complex processes relying on interaction between somatic and visceral elements, moderated by learned behavior. Urinary viscera and pelvic floor must interact with higher centers to ensure a functionally competent system. This article aims to describe the relevant anatomy and neuronal pathways involved in the maintenance of urinary continence and micturition. Review of relevant literature focusing on pelvic floor and urinary sphincters anatomy, and neuroanatomy of urinary continence and micturition. Data obtained from both live and cadaveric human studies are included. The stretch during bladder filling is believed to cause release of urothelial chemical mediators, which in turn activates afferent nerves and myofibroblasts in the muscosal and submucosal layers respectively, thereby relaying sensation of bladder fullness. The internal urethral sphincter is continuous with detrusor muscle, but its arrangement is variable. The external urethral sphincter blends with fibers of levator ani muscle. Executive decisions about micturition in humans rely on a complex mechanism involving communication between several cerebral centers and primitive sacral spinal reflexes. The pudendal nerve is most commonly damaged in females at the level of sacrospinous ligament. We describe the pelvic anatomy and relevant neuroanatomy involved in maintaining urinary continence and during micturition, subsequently highlighting the anatomical basis of urinary incontinence. Comprehensive anatomical understanding is vital for appropriate medical and surgical management of affected patients, and helps guide development of future therapies.

The use of live fluorescence staining techniques in surgery: a review.

Intraoperative fluorescence may allow improvements to existing surgical procedures or offer scope for new operations. Despite articles describing its use dating back more than a decade, its emergence as a commonly used adjunct is still anticipated. While awareness and availability of special equipment may limit the uptake of these techniques, intraoperative fluorescence could represent a key innovation in the future of surgery. Further awareness of techniques and more clinical trials are needed to promote a wide base of clinical expertise from which further innovations can be made. This literature review begins with a discussion of the physics and chemistry of fluorophores and the properties needed for use in clinical practice. Uses in the majority of surgical specialties will be considered and the current literature addressed. Common uses include delineating hollow visci such as blood vessels or demonstrating pathology such as tumors. Fluorescent stains used have been safe, effective, and often easier to use than the established methods. Finally, novel materials such as antibodies and nanoparticles will be mentioned as new developments on the horizon of intraoperative fluorescent staining.