A system of practical medicine. By American authors. Vol. 3

by Unknown

Paralysis of the Arytenoideus—Central Adductor.

The function of this muscle is to approximate the arytenoid cartilages. Its paralysis leaves the posterior borders of the cartilages separated, even though the vocal processes are by the action of the lateral crico-arytenoids made to approach the median line. There is left a triangular opening at the base of the cartilages, through which the air escapes in the act of speaking. This, the cartilaginous portion of the glottis, remains patent even though the anterior three-fourths of the space be closed. The result is generally, but not always, a loss of speech. The air whistles through this opening, but phonation is difficult or absent. The causes are to be sought in the derangements resulting in the loss of power of the other muscles. Upon examination with the laryngoscope the triangular opening is readily seen. The ligamentous portion of the glottis is seen to close in the effort to speak, while the cartilaginous portion is widely open. There is no other morbid condition necessarily present. The trouble is frequently associated with paralysis of the adductors of the two sides—that is, the lateral crico-arytenoids. In these cases there is complete separation of the cords throughout the whole length.

The DIAGNOSIS is easy except in instances where there is ankylosis of the articulation of the cartilages. Even in these cases a careful study of the parts, as revealed by the mirror, will enable the observer in most instances to recognize evidence of structural disease on the walls of the larynx. There will also be a history of some antecedent affection, such as syphilis or tuberculosis, or possibly arthritis. The course and termination of this form of paralysis depend largely upon the etiology in any given case.

Paralysis of the Tensors of the Vocal Cords.

It will be remembered that these are in two groups, the internal and external.

The internal are the thyro-arytenoids. While their function is in part still a matter of discussion, it is very generally conceded that they have to do with the form and tension of the cords. Their paralysis produces a very marked derangement of the functions of the larynx as the organ of speech. They act ordinarily along with the crico-thyroids, but from the fact of their separate innervation it would seem very probable that they should be the seat of special functional derangements. In fact, it is true that their paralysis in a limited number of cases is found to be quite independent of any disturbances of the external tensors.

ETIOLOGY.—In addition to the general causes of laryngeal paralysis, the use of the voice in an unnatural or too high a key or the too long-continued use of the organ may result in a temporary or even permanent impairment of the power of these muscles. Their exposure to the causes of inflammation, lying as they do so near the surface of the mucous membranes, subjects them to the morbid influences of the catarrhal troubles to which the glottis is liable. They are probably more frequently affected than the literature of the subject would lead us to suppose, as in many cases the disease is temporary.

SYMPTOMS.—These consist mainly in the alteration of the voice. It is hoarse, the register is lower, the quality is uneven. Occasionally a note is, if not lost, uttered with difficulty; some letters, such as the aspirates, requiring the careful adjustment of the glottis, are articulated with great uncertainty. There is what has been called a rattling of the voice. It is quite impossible to sing or to speak long in a high key; even prolonged ordinary conversation gives rise to fatigue, for the reason that there is so great a waste of air in the effort. The pressure upon the under surface of the cords in their relaxed condition forces its way upward and through the glottis without throwing them into normal vibration.

DIAGNOSIS.—The laryngeal mirror reveals the glottis only partly closed. There is an oblong opening extending from the thyroids to the base of the arytenoid cartilages. The vocal processes even are not brought to the median line, but are so far apart as to leave a noticeable slit between them. It seems from this fact that these muscles are therefore the aids of the lateral crico-arytenoids in the rotation of the cartilages on their bases. In the effort at phonation the cords are seen to move with difficulty. The disease may be unilateral or bilateral.

This form of paralysis in course and termination does not in any essential respect differ from other paralyses of the larynx. The duration is therefore very uncertain, and will depend largely upon the cause of the affection.