732 Paralj'sis of the Recurrent Nerve. 



or later the motor fibers lose their conductivity with resulting 

 paralysis and atrophy of the muscles supplied by them. For 

 some unknown reason it is only the nerve fibers supplying the 

 muscles dilating the glottis that are affected in the first in- 

 stance, but afterwards the others may become paralyzed. In 

 exceptional cases the muscles constricting the glottis are first 

 attacked, or both dilators and constrictors may be affected 

 simultaneously. According to Malkmus this is the common con- 

 dition. As a result of the infranuclear paralysis and con- 

 sequent relaxation of the muscles, the vocal cord on the affected 

 side does not move at all or only slightly, but is drawn towards 

 the middle line by the unaffected constrictor of the larynx. It 

 may, however, be forced into the lumen of the larynx together 

 with the arytenoid cartilage by a forcible inspiration, but in 

 either case there is stenosis of the larynx. Paralysis of the 

 muscles causing closure of the glottis destroys the power of 

 coughing. In time the conductivity of the sensory nerves is 

 lost with the result that there is loss of sensation in the mucous 

 membrane of the diseased side, and also to some extent of the 

 opposite side, because some fibers of the nerve may pass from 

 one side to tlie other. 



Anatomical Changes. In the early stages and in slight 

 cases the only recognizable lesions are pale yellow streaks in 

 the posterior crico-arytenoid muscle. These streaks may also 

 be present to a less extent in the lateral crico-arytenoid muscle 

 and the transverse arytenoid. In severe cases there is degen- 

 eration of a number of the fibers, and finally the muscle may 

 be pale yellow or grayish-red in color and flattened in shape. 

 If the recurrent nerve be exposed the reduction in the size of 

 the nerve and its gray color indicate the degeneration that 

 has occurred, but as a rule, the first exact information as to 

 the diseased condition of the nerve can be obtained only by his- 

 tological examination. 



According to Siissilorf the portion of tlie nerve lying between the aortic arch 

 and the trachea is normally flattened. Liihrs states that the left nerve is thinner 

 than the nerve on the right side. 



Symptoms. The most striking s^miptom is stridor in the 

 larynx during inspiration. The sound varies in different cases 

 and with few exceptions is heard only during movement. The 

 character and intensity of the sound depend upon the degree 

 of the stenosis, and continued exercise or great exertion 

 are determining factors in the production of the sounds. 

 Thus in a slight case great muscular exertion, such as gallop- 

 ing on soft ground, causes only a slight whistling sound, while 

 in the later stages of tlie condition, in severe cases, or in cases 

 in which the constrictors are perfectly or practically healthy, 

 Avhile there is paralysis of the dilators of the glottis a few mo- 

 ments ' trottini>- are sufficient to cause a much more audible 



