[Anatomo-functional study of 37 patients with monolateral chord paralysis]

The authors present a study of 37 patients affected by monolateral vocal cord paralysis in order to analyze etiology, degree of dysphonia and possible recovery of vocal function. The patients underwent the following tests: case history to determine the vocal characteristics prior to the lesion; video-laryngoscopy to define the position of the paralytic cord on the horizontal glottic plane and any compensation mechanisms; determination of the degree of dysphonia (light, moderate, severe, aphonia) on the basis of psycho-perceptive parameters; spectrography evaluated in classes (I, II, III and IV) according to Yanagihara. Analysis of the data obtained makes it possible to draw the following conclusions: the most frequent etiology encountered by the otorhinolaryngologist is surgical (particularly subsequent to thyroidectomy); the position taken by the paralytic vocal cord does not appear to determine the degree of dysphonia; during the period immediately after occurrence of the lesion (0-4 months) the vocal disorder is more intense and tends to be reduced thereafter, attenuated by a spontaneous compensation mechanism. In this regard, it must be pointed out, however, that such compensation can prove bad or even dangerous for good vocal function (falsetto voice); speech therapy makes it possible to nearly totally normalize vocal function in all patients presenting moderate dysphonia and in 60% of those with severe dysphonia. In the remaining 40% of those patients with severe dysphonia a partial improvement of vocal function was seen (from severe dysphonia to moderate dysphonia). This was determined by the fact that several negative prognostic factors came into play simultaneously in these patients (i.e. advanced age, longer time gap since the lesion occurred, position assumed by the paralytic cord) which prevented them from achieving better phonatory results.