Hemorrhages of several months' standing may be indicated either by a brownish-red patch somewhat firmer in texture than the surrounding brain-substance, or by a cavity with firm walls, which often has strings and septa of connective tissue running across it, so as to convert it into a kind of spongy mass filled with brownish fluid.
The most important changes which are found in most if not all cases of ordinary hemorrhages (i.e. such as do not depend upon violence or cachexia) are those of the blood-vessels. They are not, however, visible in the ordinary inspection of the brain at an autopsy, but require to be carefully sought for, either with the microscope or a somewhat tedious process of washing. For this reason there are no trustworthy statistics of large numbers to determine in how large a proportion of all the cases alterations in the blood-vessels are to be found, and in what form. There can be but little doubt, however, that those cases in which no form of arterial disease is present (if, with the reservation just noted as to violence or cachexia, such exist) are to be looked upon as rare exceptions.
The presence of miliary aneurisms in the brain had been noted in some cases, and even in cerebral hemorrhage, without the great importance of the observation having been perceived; but the extended and careful observations of Charcot and Bouchard first showed how extremely common their presence is, while in many instances they were found actually ruptured. These aneurisms are present in the largest numbers in the regions of the brain where hemorrhage is most frequent, and at the age when death from apoplexy is most likely to occur. They have been found at the age of twenty, but very rarely at early ages, while after forty they are not uncommon. It is of course not always that they have gone on to rupture, but may occasionally be found where no hemorrhages have taken place. It is not going far, however, to infer that in such cases the hemorrhage was not very distant.
These aneurisms are dependent upon a periarteritis which is diffused more or less widely over the cerebral arteries, but not over those of the rest of the body. The larger arteries get a thin and shining appearance, compared by Charcot and Bouchard to the skin of an onion, while the smaller ones present besides distinct aneurisms, bulgings and irregularities of outline. This condition may be—and, as would be at once suggested from the age at which both lesions are met with, is—very likely to be associated with atheroma, but it is not the same thing, since the development of the aneurisms depends upon a periarteritis, and that of atheroma upon an endarteritis. It may be remarked, also, that atheroma usually does not affect the very small arteries which bear the aneurisms and give rise to the hemorrhage.
These aneurisms are visible to the naked eye, being from two-tenths to one millimeter, or a little more, in diameter, while the artery to which they are attached can be seen by the naked eye or with a lens magnifying two or three diameters. They may be strung along a small artery like beads or be found in groups like a bunch of grapes. Charcot and Bouchard found them in every case of cerebral hemorrhage which they examined, and, although the possibility of other sources was admitted, concluded that in by far the greater number of cases, excluding those dependent upon traumatism or hemorrhagic diseases, the blood effused in the brain has its origin in one of these aneurisms. The presence of these aneurisms has been abundantly established by other observers, and the fact that they are not usually demonstrated proves nothing except the amount of care and time necessary to find them. One does, however, find occasionally noted that they were sought for and not found. The statements of Charcot and Bouchard relate, so far as their own observations are concerned, and as they themselves remark, chiefly to aged persons, but in their first series of 66 cases there is found 1 of twenty and 1 of forty years of age. The patient of twenty was a semi-imbecile and a drunkard. Extensive cerebral hemorrhage, with atheroma, in the circle of Willis has been found in an apparently healthy and well-nourished boy of fifteen.2
2 Baker, Annals of Anat. and Surg. Soc. Brooklyn, 1879, p. 40.
Larger aneurisms, often multiple, are not very infrequent upon the arteries at the base of the brain. They may before their rupture give rise to symptoms of pressure like any other tumor, and may also be the source of hemorrhage, which is usually meningeal. They are not infrequently symmetrical, and a place of election is one of the early bifurcations of the middle cerebral.
Coats3 states that aneurism of the larger arteries is the most frequent source of hemorrhage in persons under fifty. They may be due to embolism, producing, when the occlusion is not complete, mechanical injury to the walls of the vessels by the constant hammering upon them of the embolus under the impulse of the blood. If this etiology is a common one, it accounts for the frequent situation of these aneurisms in the middle cerebral arteries.
3 Glasgow Med. Journ., 1882, xvii. 109.
Small vessels in a condition of fatty degeneration are often found in the neighborhood of a cerebral hemorrhage. In some cases, undoubtedly, the degeneration is a consequence of the injury to which the cerebral substance has been subjected, but they have also been found too soon after the hemorrhage for this explanation to hold; and in cases where no aneurisms are present the older supposition, that hemorrhage results from this kind of degeneration, seems to have a certain foundation, even if only in a minimum of cases.