A Study of the Vibratory pattern of Vocal Cords in Unilateral Laryngeal Paralysis

Abstract

Slow motion films of the vibration of the vocal cords were analized in 12 cases of unilateral recurrent laryngeal nerve paralysis. The vibratory pattern of vocal cords in unilateral laryngeal paralysis was classified into three groups. Bilateral vocal cords vibrate regularly and symmetrically in the first group which may be called the paretic type. It is considered in this type that the electromyography of the intrinsic laryngeal muscles shows normal discharge and their muscle atrophy is scarcelyo bserved. In the second group, the vibration of bilateral vocal cords is irregular and asymmetrical, especially different in both phases with little variation of the amplitude. Pathologic discharge such as fibrillation voltage is observed. The atrophy of the muscles may be increasing or recovering in this type. In the third group, the vibration of the vocal cord on the paretic side is remarkably irregular and little in its amplitude. This type may be named the paralytic type, and the muscles are extremely atrophic and electromyographically silent.