But here also, opinions differ, while one observer holds that the threatened organ is the trachea with the large bronchial tubes; another believes it to be the aorta that is in clanger, or the pulmonary artery, or the superior vena cava and its two larger branches. or the veins of the lungs, or part of the heart, and last, the vagus, phrenic and sym pathetic nerves. Most of these opinions are mere hypotheses, arrived at because of the topographical and anatomical relations of these vari ous structures to the glancl, and are scarcely supported by positive findings. As an objection to the above in a general way, one might- an swer, that hyperplasia of the thymus would act permanently- and gradu ally rather than suddenly, if pressure was being exerted by it upon one of these important organs.
The occurrence of a sudden swelling has never been proven, and all other attempts at explanation cannot withstand criticism. Not even the theory that a eritically narrowed upper thoracic aperture, might be still more narrowed by a sudden forceful extension of the head.
flow can anyone imagine the thymus everting pressure of any importance at all, upon the neighboring organs? The absolute weight of the gland, which has I think, wrongfully played such an important part for so long a time, cannot lie taken into consideration for the rea son that the gland being bound to all the surrounding organs by con nective tissue is in a manner hanging in place; and besides it could only act upon the organ upon which it lies when the body is in the supine position; and then with only a fraction of its weight.
A benignly enlarged thymus can only afflict the neighboring organs within the measure of its osmotic pressure and it will grow in the direct ion, obviously, of the least resistance. That it could compromise a. normal trachea or normal large arteries is therefore exclucled. We know that an aneurysm can erode bones. How is it possible then that so power ful a vessel as the aorta could be narrowed by pressure exerted upon it by the thymus, as is thought possible by some authors? (Lang, Cohn.) In reality, pressure seams have been found on large thyrni due to compression exerted upon them by the intiontinate artery and by the manubrium.
The large veins, possessing little tension, would appear to be in more danger; but is it at all probable that in the depths of the thorax an exchange pressure could take place, affecting the veins only, and not rather affecting the so easily compressed lungs! The veins mentioned by these authors lie below the "critical aperture" and besides, no sud den closure of the veins has been verified on post mortem.
A serious consideration must be given to those cases of narrowing of the trachea and bronchial tubes which have been proven as such, and which have been repeatedly observed since they were described by Somma; on account of their being analogous with the deformities of the trachea caused by struma, and with the cases of death caused by struma goitre.
Even if the healthy trachea of the newborn infant, according to the expciriments of Tarnmassia and Scheele, can withstand much pressure, still, a trachea changed by disease, might show considerable softening of the cartilaginous ring, and in such eases as Malian and Lange describe, might be compromised by a large thymus (Platindler). Still, such changes have never been proven and should they occur, we would expect a tracheo-stenosis long before death occurred.
A clinical picture of this kind does exist indeed, in the early suckling age and would best be called by the name chosen by Ilochsinger, as: Slriclor Thymicus lnjantecm. This is a more or less severe tracheo stenosis, which generally develops during the first weeks of life; but which sometimes is present at birth and which increascis under excite ment. This disease generally ends benignly, by the gradual disap pearance of the symptoms, as the infant grows and the trachea be comes more firm. In very severe cases, courageous operators have undertaken a thymus plastic operation with success. This was first done by Rehn.
It would not do to mistake the foregoing picture for the so-called stridor congenitus. It differs from the latter in not being a pathological unity, but in being due to different causes (Breeeli) one of which might be hyperplasia of the thymus.
Coming back to the former question, the attempts to explain un expected deaths in childhood, from the local effects of Ityperplasia of the thymus, must be looked upon as a failure, up to this time. Even the stridor thymicus, is an exceptionally chronic picture of illness and can not be used as a support for the arguments of those who take that view.
A. Pahad in ISSO was forced, on the strength of his own niany experiences as pathologist, to the same conclusions. But lie only declined to accept the false explanations; while Ile confirmed the fact of the coincidence of sudden death with the presence of an enlarged thymus, and gave it quite a new interpretation. According to him, the cause of sudden death, apparently impossible to explain, lies in a peculiar constitutional anomaly; which makes its possessor weak and less able to withstand attacks of illness, death being easily produced from trifling causes.