2010 Volume 61 Issue 4 Pages 353-360
Hyperthermotherapy using steam has been long known, over since the age of Hippocrates. Because it involves no medicines and does not have side effects, it has become a popular health-promoting method. Although this method has shown effective results for nasal diseases, analysis for pharyngeal and laryngeal diseases has not been adequate. Recently handy steam inhalers requiring no water nor electricity have been developed. This method involves high temperature and humidity without use of drugs. It uses the heat produced by oxidization of iron oxide. Singers, actors and teachers sometimes need vocal care immediately before their performances. For voice care in these cases, analysis of voice and EGG (electroglottography), and images (2000 frames/sec) of vocal cord vibration and the state of air tract fluid by high-speed color camera (Memrecam GX-1 Plus : Nac) were carried out pre- and post-inhalation in 4 cases. The following results were revealed. In the cases of normal vocal cords, APQ, PPQ and NHR decreased between pre- and post-inhalation, so the voice improved. New color images by high-speed camera have enabled observation of vocal cord vibration and the state of air tract fluid. The fluid exists at two positions of the vocal cords during phonation. The first is on the surface of the supraglottis. This fluid comes from the subglottic space at the onset of phonation. It mixes with the fluid on the supraglottis, and is shaped like a spindle rotating on the surface of the glottis. At the moment of breathing, this spindle-shaped fluid descends to the subglottis. As a result the fluid added by inhalation is useful as lubrication of the vocal cord. Dr. Kawaida reported a dynamic study on air tract fluid in lubrication of the larynx during phonation using an excised canine larynx. We agree with his theory based our observations using high-speed color photography. The second fluid exists at the anterior surface of the vocal cords. It appears like a web. During the opening phase of vocal cord vibration this fluid is stretched thin, while during the closing phase it thickly covers the anterior glottis. This suggests the web causes the EGGOQ to decrease. In the case of vocal cord swelling, the fluid exists near the tip of the swollen vocal cords, not at the anterior glottis. We hypothesized that the fluid on the surface of the supraglottis makes the tips of the swollen vocal cords heavy and accelerates the velocity of the closing phase, making the EGGOQ high. A handy steam inhaler can be successfully used for lubricating the larynx and for care of some professional voices.
