Externally induced vibration on massive vocal fold.

For successful performance of phonosurgery, it is most important to maintain the flexibility of the vocal fold. Unfortunately, however, there has been no direct effective method so far for assessing the flexibility of the vocal fold membrane. If the vocal fold surface showed any abnormal region where good vibration could not be observed, reduced flexibility was expected in this area. Hitherto, for observation of the vocal fold vibration, a laryngostroboscope has been in use clinically. However, the laryngostroboscope can not be applied effectively when the patient is unable to phonate for reasons such as under general anesthesia with tracheal tube or when his/her voice is too hoarse to drive a laryngostroboscope well. Instead of observing phonatory vibrations, Fukuda designed a new vibra tory method that makes it possible to externally induce wavelike motion on the surface of the vocal fold even under aforementioned unfavorable conditions. In this study, by using the new method, it was possible to observe externally induced vibration on the normal membrane surrounding the abnormal region with mass as well as in the abnormal region itself such as in polyp, cyst, or polypoid degen 都築 達,藤 岡 正,福 田宏 之,大 木和明,川 崎 順久,紀 太康一 Reprint requests to: Dr. Tohru Tsuzuki, Department of Otolaryngology, Koshigaya Hospital, Dokkyo University School of Medicine, 2-1-50, Minamikoshigaya, Koshigaya, Saitama 343, Japan