The anatomist is also always in danger of erring, as the thymus, keeping step with the general nutri tion, will be found small in cases where wasting diseases have been present, and thus the size be underestimated, while on the other hand, he will over value the large thytni whieb he finds in well nour ished individuals who have died after short illnesses.
The skeptical anatomist will in consequence not acknowledge that hyperplasia is possible; or if he doe.: will claim that it can occur only in exceptional cases. Even the compression of the trachea, which has for long been considered a sure proof, has now lost credit, since Richter produced it artificially, showing instructive preparations.
The question for the clinician is not any easier. Palpation of the thymus does not give any points by which to estimate its size. The deformity known as pigeon breast caused by thorax-rachitis, is not even remotely caused by an enlarged thymus.
Percussion of the Ihymus has been very carefully studied out by Blumenreich, and is of much greater value than palpation. Tbe dulness .diminished resonance) of the thymus covers a space the shape of a somewhat unequal triangle whose base is formed by a line drawn be tween the two sternoclavicular joints, and whose rounded off point lies downward on abottt a line with the second rib, or a little lower, and whose side: reach asymmetrically up across the sternal lines; on tbe left side more so than on the right. Between the thymus dulness and the heart dulness there is a zone where in normal cases the normal percussion note over healthy lung tissue is heard, because of the situa tion of the borders of the lungs. If this zone be dulled, or if these borders be lapped over one em., then one may diagnose a very large thymus, if all other causes of dulness have been excluded. This dulness on per cussion can only be found up to the sixth year of life. Afterwards it lessens more and more.
Enlarged and caseated mediastinal glands are often the cause of mistaken diagnosis. These are found particularly in scrofulotuber CICCU,: infants. ;According to my experience, when other glands in this region are enlarged the same mistake is liable to occur.
When one can establish without a doubt, that thc area of thymus dulness is greater than normal in any given case, without other disease being present it may then be stated that a diseased enlargement of the thymus is present.
The same rule applies to the results established by Hoehsinger, by the use of the Rautyen rays: when showing the enlarged thymus. The middle shadow thrown by the thymus under normal conditions, rests on the shadow thrown by the heart, just as the slender neck of a bottle is fixed on the body of the bottle. In many cases this shadow of the thymus is more or less spread out. In these, after careful clinical examination, enlargement of the thymus was suspected. But sometimes one receives such pictures when all the clinical symptoms of an enlarged thymus are absent.
Are these cases of hyperplasia? Aside from quite isolated and monstrous eases found in the literature, both anatomists and clinicians have reached this conclusion by exclusion always however cum gram, sails.
This somewhat critical discussion of the objective diagnostic expedients was necessary, in order that a stand might be taken on the frequently discussed question, as to the relation. of sudden deaths in infancy to hyperpla.sia of the thymus. Such catastrophies happen much oftener during the first eighteen months of life than in adults. The autopsy in many of these cases gives a sufficient explanation of the death. The acute capillary bronchitis of sucklings plays a prominent rale, and the surprising part of such deaths may be sufficiently explained by the lack in these cases, of subjective complaints and of objective observations.
Nevertheless, a number of such cases remain, which even the most careful autopsy does not fully clear up. -When no long wasting illness has preceded the death, and a considerably, enlarged thymus gland is found, WC are apt to explain the sudden death as due to this cause, after the observations of Baginsky and Grawitz. Numerous published reports have given plenty of material for the thorough review of the question. Several years ago it was critically sifted. Since then, several new communications have been added to the literature, but without bringing out anything of value. These authors are of the opinion that hyperplasia of the thymus could cause sudden death by pressing upon the neighboring vital organs; either by sudden enlargement of the gland, or by a particularly unfavorable position of the head, or by both. Some other far-fetched hypotheses have been advanced.