Tomographic aspect of paralysis of the vocal cords.

Abstract

Tomographic study of laryngeal paralysis has received little mention in the literature. Many articles have been written describing tomographic exploration of the physiology of the larynx during phonation (1–4, 6, 8, 9–13), but only Canuyt, Gunsett and Greiner (5) have dealt with the tomographic appearance of the paralyzed larynx. While it is true that paralysis of the vocal cords can be diagnosed easily by mirror examination, its tomographic description is of interest for several reasons. In the first place, there are many patients on whom indirect laryngoscopy is impossible for one reason or another, and in these instances tomograms may settle the diagnosis; secondly, the study of the paralyzed larynx gives a better understanding of its limited mobility in the presence of local disease. The recurrent laryngeal nerve innervates all the muscles of the larynx except the cricothyroid, which receives its nerve supply from the superior laryngeal nerve (7). Any pathological process involving the recurrent laryngeal nerve in its course will produce paralysis. In the series of cases upon which the present paper is based, malignant tumors in the thorax or in the neck have been the main etiological factors. A few cases of laryngeal paralysis secondary to thyroidectomy have been seen, allowing a study of the changes which take place in long standing denervation. In all cases lateral films of the neck were obtained before tomography. The only reliable sign found in this position is a slight anterior displacement of the paralyzed arytenoid cartilage; this is evident, however, only when the cartilage has undergone some calcification. Changes in size and shape of the ventricle in the lateral films which have been emphasized in the literature are neither constant nor sufficient for diagnosis. Visualization of the ventricle is almost always better when there is paralysis of one of the vocal cords. The flaccid cord produces the changes in appearance, mainly when the films are made during phonation or with the Valsalva maneuver. There is no intention of denying the value of lateral films for differential diagnosis, as they are invaluable for that purpose and should be taken routinely before tomograms are made. The best tomographic sections for demonstration of the vocal cords are obtained at 2 and 3 cm. from the skin, at the level of the thyroid notch. The following observations are made on such films: 1. The paralyzed cord is elevated (Figs. 1 and 2). When the arytenoid or corniculate cartilages are well calcified, this elevation will be better demonstrated by the higher position of the calcific density compared to the normal side (Fig. 2). 2. There is better visualization of the ventricle, which appears wider on the paralyzed side (Fig. 3). This is quite evident during phonation and may be seen best with the Valsalva maneuver. 3. The arytenoid and base of the aryepiglottic fold hang toward the normal side and are more prominent on the paralyzed side (Fig. 2).