Inspiratory vocal cord dysfunction, a new approach in treatment.
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Vocal cord dysfunction is a well recognized respiratory condition in which adduction of the vocal cords during either inspiration or expiration, or both, causes functional airways obstruction. Diagnosis is usually made by laryngofibreoscopy, however treatment of this condition has generally been unsatisfactory, requiring a multi-disciplinary approach consisting of speech therapy, psychological counselling, sedatives and anaesthetic agents. Here we use an innovative approach which requires relatively inexpensive and simple anaesthetic equipment in order to manipulate airways resistance and thus reduce any vocal cord dysfunction as it occurs. The patient involved found instant relief when using this simple device which is easy to use and is portable. (+info)
Paradoxical vocal cord motion causing stridor after thyroidectomy.
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Two women developed stridor immediately after thyroidectomy as a result of paradoxical vocal cord motion. In both cases the cord function showed a normal pattern during vocalisation but paradoxical movement was seen at laryngoscopy during tidal breathing. The abnormality improved in both patients over time with speech therapy. Whilst the syndrome of paradoxical vocal cord motion is classically thought to have a largely psychological aetiology, subtle interference with laryngeal innervation at surgery is more likely to have been the cause in these cases. (+info)
Vocal tract function in birdsong production: experimental manipulation of beak movements.
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Kinematic analyses have demonstrated that the extent to which a songbird's beak is open when singing correlates with the acoustic frequencies of the sounds produced, suggesting that beak movements function to modulate the acoustic properties of the vocal tract during song production. If motions of the beak are necessary for normal song production, then disrupting the ability of a bird to perform these movements should alter the acoustic properties of its song. We tested this prediction by comparing songs produced normally by white-throated sparrows and swamp sparrows with songs produced when the beak was temporarily immobilized. We also observed how temporarily loading the beak of canaries with extra mass affected vocal tract movements and song production. Disruption of vocal tract movements resulted in the predicted frequency-dependent amplitude changes in the songs of both white-throated sparrows and swamp sparrows. Canaries with mass added to their beak sang with their beak open more widely than normal and produced notes with greater harmonic content than those without weights. Both manipulations resulted in acoustic changes consistent with a model in which beak motions affect vocal tract resonances, thus supporting the hypothesis that dynamic vocal tract motions and post-production modulation of sound are necessary features of normal song production. (+info)
Simplified rat intubation using a new oropharyngeal intubation wedge.
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Our new oropharyngeal intubation wedge made from a plastic 3-ml syringe has been used successfully for the expansion of the oropharyngeal cavity and visualization of vocal cords for endotracheal intubation in the rat. All the animals we used tolerated the intubation and ventilation procedures in a series of experiments. After the proper setting of the respirator, vital signs were maintained within normal range. The postmortem examination and measurements in the upper airway confirmed that the endotracheal tube was properly sited and also demonstrated the precise size of the device that should be used. The main advantages of this method include low cost, simplicity, and reliability. Furthermore, because no expensive, elaborate, difficult-to-operate, or hard-to-get special equipment is needed, this technique can be used in every laboratory. (+info)
Physical factors affecting the cost and efficiency of sound production in the treefrog Hyla versicolor.
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The metabolic cost, energy output and efficiency (i.e. the ratio of energy output to metabolic cost) of sound production were compared among male grey treefrogs (Hyla versicolor) as a function of body size and temperature. The effects of call length (in notes per call) and dominant frequency (in kHz) were also considered. Cost, determined from the amount of oxygen consumed, averaged 12.1 mJ per note and was dependent only upon body mass. Acoustic energy per note, determined from oscillograms of recorded calls, averaged 0.34 mJ and was dependent only upon temperature. Conventional theory suggests that the efficiency of sound production should be a function of the ratio of the linear size of the radiating structures to the wavelength of the sound generated (i.e. efficiency is assumed to be a function of the product of mass(0.33) and frequency), but efficiency in H. versicolor was found to be a function of the product of temperature(2.1) and mass(-1.08). Adjusting for temperature and body mass, the efficiency of sound production in H. versicolor (average 2.4 %) is greater than the efficiency of other frog species for which data are available. Temperature may affect acoustic energy output because trunk muscle contraction speed increases with temperature, which increases the velocity of airflow across the vocal cords. (+info)
Localization of the gene for distal hereditary motor neuronopathy VII (dHMN-VII) to chromosome 2q14.
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Distal hereditary motor neuronopathy type VII (dHMN-VII) is an autosomal dominant disorder characterized by distal muscular atrophy and vocal cord paralysis. We performed a genomewide linkage search in a large Welsh pedigree with dHMN-VII and established linkage to chromosome 2q14. Analyses of a second family with dHMN-VII confirmed the location of the gene and provided evidence for a founder mutation segregating in both pedigrees. The maximum three-point LOD score in the combined pedigree was 7.49 at D2S274. Expansion of a polyalanine tract in Engrailed-1, a transcription factor strongly expressed in the spinal cord, was excluded as the cause of dHMN-VII. (+info)
Paradoxical vocal cord adduction mimicking as acute asthma in a pediatric patient.
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We report an adolescent girl with paradoxical vocal cord adduction who presented with acute onset of hyperventilation, wheezing and stridor that did not respond to bronchodilator and anti-inflammation therapy. The paradoxical vocal cord motion was confirmed by flexible fiberoptic bronchoscopic examination. We found the stridor was induced by hyperventilation, and was caused by paradoxical vocal cord movement. The abnormal cord motion may be psychogenic and could be misdiagnosed as asthma. It is important to investigate the underlying background and social history and to avoid unnecessary use of beta-agonists, steroids, and even endotracheal intubation or tracheostomy. (+info)
Regulation of vocal fold transepithelial water fluxes.
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Vocal fold hydration is critical to phonation. We hypothesized that the vocal fold generates bidirectional water fluxes, which are regulated by activity of the Na(+)-K(+)- ATPase. Western blots and immunohistochemistry demonstrated the presence of the alpha-subunit Na(+)-K(+)-ATPase in the canine vocal fold (n = 11). Luminal cells, basal and adjacent one to two layers of suprabasal cells within stratified squamous epithelium, were immunopositive, as well as basolateral membranes of submucosal seromucous glands underlying transitional epithelia. Canine (n = 6) and ovine (n = 14) vocal fold mucosae exhibited transepithelial potential differences of 8.1 +/- 2.8 and 9.3 +/- 1.3 mV (lumen negative), respectively. The potential difference and short-circuit current (ovine = 31 +/- 4 microA/cm(2); canine = 41 +/- 10 microA/cm(2)) were substantially reduced by luminal administration of 75 microM acetylstrophanthidin (P < 0.05). Ovine (n = 7) transepithelial water fluxes decreased from 5.1 +/- 0.3 to 4.3 +/- 0.3 microl x min(-1) x cm(-2) from the basal to luminal chamber and from 5.2 +/- 0.2 to 3.9 +/- 0.3 microl x min(-1) x cm(-2) from the luminal to basal chamber by luminal acetylstrophanthidin (P < 0.05). The presence of the Na(+)-K(+)-ATPase in the vocal fold epithelium and the electrolyte transport derived from its activity provide the intrinsic mechanisms to regulate cell volume as well as vocal fold hydration. (+info)