In patients with multiple sclerosis (MS) non-communicating syringomyelia (NCS) has been described as an incidental finding in case studies and small case series. NCS in MS patients commonly leads to uncertainty particularly as the clinical picture of NCS is variable and surgical therapy may be considered. Up to date little is known about the prevalence and clinical importance of NCS in MS. We r...

This research presents a model of the avian vocal tract, implemented using waveguide synthesis and numerical methods. The vocal organ of the songbird, the syrinx, has a unique topography of acoustic tubes (a trachea with a bifurcation at its base) making it a novel subject for waveguide synthesis. In the upper region of the two bifid bronchi lies a nonlinear vibrating membrane—the primary reson...

Two cases are reported of syrinx associated with an intramedullary metastasis. The first presented with hyperaesthesia in the right arm and bilateral pyramidal leg weakness, the second with a partial right sided Brown Sequard syndrome with a sensory level at D6. A possible pathological mechanism for the development of such syrinxes is discussed.

The pathophysiology of posttraumatic syringomyelia is incompletely understood. We examined whether local ischemia occurs after spinal cord injury. If so, whether it causes neuronal mitochondrial dysfunction and depletion, and subsequent energy metabolism impairment results in cell starvation of energy and even cell death, contributing to the enlargement of the cavity. Local blood flow was measu...

AIM Previous studies have not identified a preferred surgical technique to treat posttraumatic syringomyelia. Both syringopleural shunting and arachnoidolysis are used in neurosurgery practice for the surgical treatment of posttraumatic syringomyelia. In this study, we present a new technique designed to achieve a better outcome following surgery. MATERIAL AND METHODS A 33-year-old man, who e...

Myrmornis torquata has often been considered an intermediate form between the ground antbirds and the typical antbirds. Although molecular phylogenies have consistently placed M. torquata in the Thamnophilidae (typical antbirds), this species has not been the subject of a thorough anatomical study, and no phylogeny based on morphological characters has been published. We undertook a cladistic m...

In this research, a method previously applied to improve a digital simulation of the avian syrinx is adapted to the geometry of the clarinet reed. The clarinet model is studied with particular attention to the case when the reed beats again the lay of the mouthpiece, closing off air flow to the bore once each period. In place of the standard reed table which gives steady-state volume flow as a ...

We review current quantitative models of the biomechanics of bird sound production. A quantitative model of the vocal apparatus was proposed by Fletcher (1988). He represented the syrinx (i.e. the portions of the trachea and bronchi with labia and membranes) as a single membrane. This membrane acts as a valve that rapidly closes and opens during phonation.This model can be used as a basis to ad...