Fiberscopic estimation of vocal fold stiffness in vivo using the sucking method

We developed a fiberscopic device for estimating vocal fold stiffness in vivo. A small plastic tube with a hole in the side was connected to the forceps channel of the fiberscope and used as an aspiration tube under constant negative pressure. A basic experiment revealed that the maximum distance at which the vocal fold was sucked to the hole depended on the stiffness of the tissue. A preliminary study was conducted with a normal subject and four patients: one with sulcus vocalis, one with Reinke's edema, and two with carcinoma. The stiffness estimated using this method was 3 to 4 g/cm for the normal vocal fold. The stiffness for carcinoma and sulcus vocalis was significantly greater than that of normal vocal fold tissue. The stiffness of Reinke's edema did not differ markedly from that of normal tissue.