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

by Unknown

The ETIOLOGY of this form of paralysis presents some peculiar problems. In all paralyses of the individual muscles we are obliged to invoke nerve-changes in special nerve-cells in the centres from which the individual nerves have their origin—changes along the course of the nerves; or, on the other hand, some myopathic change in the muscles themselves. In the muscles now under consideration we have a special function—namely, respiration—involved. The disorder is usually limited to these muscles alone. If it becomes general, it commences here. The phonators not being involved, it is probable that in a part of the cases reported the essential cause of the paralysis must be ascribed to disease in a centre in the brain, or at least along the course of the nerve near its origin. Other cases are evidently due to pressure on the pneumogastrics or recurrents. This view has been proposed by Bosworth. Von Ziemssen and others have thought that syphilis enters very largely into the pathology of this group of cases. There has been noted, as confirmatory of this proposition, that other symptoms of central disease have been in a few instances observed. Diseases affecting the recurrents have been known to affect these muscles alone: Ingals reports cases. On the other hand, it is quite certain that in a large majority of the cases recorded there has been no satisfactory cause assigned. In nearly all of the post-mortems there has been found a degeneration of the muscles. This is as we should expect to find it where the structures have been for a considerable time in a state of inaction. The histological change may possibly be in any case only the result of the paralysis, and not the cause of it. In a few instances there has been discovered a degeneration of the nerve-trunks by which the parts are supplied. As to the causes by which the muscles may become affected, we can imagine that the exposed position suggested by Mackenzie renders them peculiarly liable to mechanical injuries from hard substances forced down the oesophagus. They are subjected to changes of temperature produced by hot and cold drinks and food. Their relation to the seat of local inflammation of a specific as well as of a non-specific character renders them liable to become involved in morbid processes. The fact that the disease occasionally occurs after diphtheria, as I have in two instances demonstrated, gives additional weight to this hypothesis. The fact probably is that there are several varieties of the affection. The want of more accurate information as to the previous history, as well as to the immediate antecedents of the attack, renders it impossible as yet to differentiate the cases due to one or other of these causes. For the present, then, we may conclude that paralysis of these muscles may depend upon either disease of the centres, disease along the track of the nerves, pneumogastric or recurrent, or to disease of the peripheral branches or fibrils, or to disease of the muscles themselves.

SYMPTOMS.—These are at first so slight that the trouble is usually not recognized till it has reached such a stage that the act of inspiration is either attended with fatigue or there is stridor which annoys the patient or alarms his friends. Soon afterward there begins to be a dyspnoea, a difficulty in breathing, especially during any active exertion and during sleep. The voice in the mean time remains normal. Expiration is free. The general health is usually undisturbed. There may be a catarrhal affection of the mucous surfaces, but if so it is quite accidental. Spasm supervenes. There is at times great difficulty of breathing, and, finally, the effort becomes so great that the patient becomes alarmed. Upon examination with the laryngoscope the vocal cords are seen in close proximity to each other even during the inspiratory effort. In fact, they are, by the pressure of the air upon their upper surfaces, brought closer together during inspiration than during expiration. They seem to act as valves which are closed by the weight of the atmosphere upon their wide, flat upper surfaces, pressing them against each other. Hence the inspiratory stridor and dyspnoea. The act of expiration is a passive one in health, and in this condition the air is easily forced out by pressing the cords away. The order of the movements of the cords is therefore changed—in the normal condition wide in inspiration, narrow in expiration; in this disease narrow in inspiration, and while not wide, at least wider, in expiration than in inspiration. In other respects the parts are normal. There is nothing to suggest the trouble except the closure of the glottis during inspiration.

The course and duration of the disease are in a large majority of cases chronic. Once established, it tends to persist. The cases of diphtheritic origin should be excepted from this statement. In those forms in which the trouble is entirely in the muscles of the part life may, so far as we know, be continued indefinitely. Where the trouble is central it is probable that the cause has a tendency to involve other parts of the brain, and in this way to lead to other, and possibly dangerous, complications. Of this, however, we know but little. The paralysis is not directly the cause of death, except as it closes the glottis. The dangers are therefore mechanical. When the patient has once been placed in a condition of safety by the operation of tracheotomy the local paralysis no longer endangers life.

Mackenzie, Von Ziemssen, Cohen, and in fact almost all writers upon the diseases of the larynx cite and publish cases by the way of illustration of the symptoms, course, and termination of this class of troubles. They are now so numerous that it would seem to be hardly necessary to do more than to give the conclusions which the recorded instances suggest. Fortunately, this form of laryngeal disease is rare, and when present it is easily recognized. The treatment is clearly indicated. In all cases in which the inspiratory difficulty is marked tracheotomy should be performed, even though suffocation does not seem to be imminent. The treatment for the radical cure of the disease must be in the main the same as that required in other forms of laryngeal paralysis.

TREATMENT OF PARALYSIS OF THE LARYNX.—The grouping of these disorders for the purpose of description has, for the reasons already given, been based largely upon symptoms. For the purpose of treatment we may properly divide them with reference to their causes. With these in view, we have, first, those cases in which the cause of the affection is within the cranium—central disease; second, those in which the loss of power is the result of disease or pressure along the course of the nerves outside the cranium and before reaching the larynx; third, those in which there is disease of the structure of the larynx itself, nerves or muscles; fourth, those in which the cause is to be found in some distant part—reflex paralysis; fifth, those of toxic origin. This last includes paralysis after typhoid fever, diphtheria, etc., as well as those produced by lead, arsenic, mercury, and possibly copper and other toxic agents.

Diseases of the base of the brain or medulla are for the most part not amenable to treatment. They are generally organic and progressive. The exception to this statement, or at least the most notable exception, is syphilis. The influence of this disorder in the production of paralysis of central origin must be admitted, but it seems to have been by many authorities overstated. The coincidence of paralysis with an earlier infection does not by any means justify the inference that the one disease has been produced by the other. When, however, there is reason to think that this relation may exist, antisyphilitics should be administered. In a few cases this treatment has been followed by marked improvement of the laryngeal disease.

Cases dependent upon malignant growths within the cranium are absolutely beyond the reach of treatment. Paralysis dependent upon bony tumors, even though they are benign in character, are also for the most part beyond the reach of surgical interference. If the paralysis is complete—that is, if all the muscles are involved—there are no indications for any operative procedure. If, however, only the nerves that supply the posterior crico-arytenoids are involved, as occasionally happens, tracheotomy should be resorted to even though the dyspnoea is not urgent. This operation places the patient in a condition of temporary safety, and gives time to resort to other means if the indications for their use can be found.

The second group of cases includes all those in which the cause of the paralysis is due to the presence of disease of the nerve-trunks, or to pressure upon the nerves between their emergence from the cranium and their terminations in the muscles of the larynx. Malignant growths and benign tumors situated along the tract of the nerves, and pinching them, are readily recognized, and when not contraindicated by other facts they should be removed. Enlargement of the thyroid gland may in some cases press upon the nerve and cause paralysis. This is occasionally relieved by appropriate treatment directed to it. Among those means which have occasionally been found efficacious for this purpose iodine or some of its compounds, and especially electricity in the form of galvanism, seem to be entitled to the most confidence. For paralysis dependent upon cicatricial pinching of the recurrent nerve-trunks relief may possibly be obtained by dissecting out the bands by which the nerves are compressed. This is hardly indicated for the partial derangements which do not endanger life, as in unilateral paralysis of the recurrent. Where the trunk of the nerve is entirely obliterated nothing can be done, and in many cases of injuries along the trunk of the recurrent it will be impossible to know that the nerve has not been destroyed in the mechanical lesion.

Paralysis caused by pressure upon the intra-thoracic portion of nerve is beyond the reach of surgical interference. When this is aneurism, disease of the apex of the lung, or pleuritis, as may possibly happen, the paralysis or paresis must of course have a history coeval with the thoracic disease. The causes themselves are unfortunately persistent and tend to terminate in death; the paralyses are therefore persistent and beyond the reach of medical or surgical relief. In cases where the posterior crico-arytenoids are especially involved, tracheotomy, as in the same condition from intra-cranial disease, should be performed. It is certainly true that there may be a morbid condition of one or both of the pneumogastrics or recurrent nerves without macroscopic changes in their structure; in such cases the use of the faradic current together with general tonics is indicated.

The third group is made up of those cases in which there is disease of the nerves or muscles of the larynx itself. It seems to be true that in most of these patients there is a derangement of the general nutrition; but this is not all: there is also a special morbid condition of these special structures. For degeneration of the muscles of the larynx there is probably no remedy; for atrophy there may be something done by different methods of exercising the muscles. The use of electricity when the muscles are still responsive to the current should be attempted. Regular applications by which they are thrown into action may result in the improvement of their nutrition. The use of them so far as they are phonators, without carrying it to the extent of producing fatigue, is also indicated. In addition to these local measures, tonics for the purpose of improving the general condition may be administered. Strychnia, with the purpose of stimulating the centres, will also be found in some cases useful. When the disease is partial, as in the case of the posterior crico-arytenoids, such operative measures as have been already indicated must be resorted to. The purpose is to prolong life, even though we cannot cure the disease.