Vibration of the vocal cords in some pathological conditions Free

Vibratory mede of some pathological vocal cords was investigated with a use of ultrahigh‐speed photography. The most frequent abnormalities in vibration in the cases of unilateral recurrent laryngeal nerve paralysis are an incomplete glottic closure, asymmetric movements of the two cords, and a decrease in or absence of mucosal wave on the affected cord. In the cases of vocal cord polyp, a relatively soft mass, the vibrating abnormal mass causes an incomplete glottic closure, a decrease in amplitude of vibration, and phase differences between movements of the affected portion and those of the nonaffected. A cancerous lesion, which always has a great stiffness, results in absence of vibration of the affected area and a hindrance to the movements of the nonaffected cord.