This result, however, is not an extremely common one. Among 43 fatal cases of interstitial nephritis, well-marked cerebral hemorrhage was found in 4; in another, cysts and brownish indurations of small size were found which might have been partly the results of embolism. This patient had had a distinct paralytic attack. In a fifth the symptoms pointed unequivocally to a large rapid hemorrhage, although it was not demonstrated by an autopsy.
Looking at it from the other side, it was found that (in another series) of 48 cases of cerebral hemorrhage with autopsy, contracted kidneys were present in 17; and the writer is of the opinion, although he has not at his command a sufficient number of facts to make such an opinion conclusive, that if a series of cases were taken of persons under forty or fifty, excluding those where a hemorrhagic disease or a valvular disease of the heart might be present, the proportion of interstitial nephritis to cerebral hemorrhage would be greatly increased; and especially so if large hemorrhages into the great ganglia or the interior of the cerebral lobes were alone considered.
The so-called apoplectic constitution should be mentioned here; that is, the stout, thick-set build with short neck and florid complexion. The popular notions as to the peculiar dangers of this condition seem to have arisen rather from suppositions as to what might be supposed to take place, from inferring a similar state of things to exist in the brain to what exists in the countenance, than from any observation as to what has actually occurred. Cerebral hemorrhage may take place with any sort of complexion or any figure, and there is no sufficient evidence that persons of the physique above described are specially liable to it. Many recent writers distinctly deny any such connection.
Intellectual pursuits have been considered a disposing cause—a theory which it would be difficult to substantiate. It is not, of course, the quality of the work, but its relation to the capacity of the individual brain, which makes any amount of thought a special strain. The cases of Dieulafoy, in which the hereditary tendency was so strongly marked, were mostly hospital cases, among which class the so-called intellectual occupations do not specially preponderate. A life of constant cerebral excitement, like that of a speculator or stockbroker, certainly seems more likely to give rise to overstrain of the vessels than the more quiet and regular, but certainly more intellectual, labor of the professional or literary man.
Thackrah15 speaks of affections of the head as frequent among professional men, but does not advert to cerebral hemorrhage in particular. He evidently considers a want of sufficient exercise in the open air a far more potent factor than mental excitement.
15 Health and Longevity, p. 183.
It is very difficult to get statistics which bear upon the influence of mental labor on the brain, since the recorded occupation of an individual furnishes but a very rough estimate of the amount of thought evolved from his brain, and a very much less accurate one of what is probably of far greater importance—the amount of friction and anxiety with which it is done.
Hemorrhagic diseases may, for the sake of completeness, be once more mentioned as among the predisposing causes.
The exciting causes of cerebral hemorrhage are those which give rise to rupture of the fragile walls either of the aneurisms or fattily degenerated arterioles. They are to be found chiefly among such conditions as increase the pressure in the cerebral vessels, chiefly, though not wholly, from the arterial side. The connection of an attack of apoplexy with hypertrophy of the heart means, as has already been shown, in a great many cases, their mutual dependence upon arterial disease, as in chronic interstitial nephritis, but it seems probable also that an unusually powerful action of such a heart might be the immediate cause of the rupture. An excited action of the heart, connected with a dilatation of the cerebral vessels, naturally increases the strain on the weak portions, and we have thus the explanation of those instances where sudden or great excitement brings on the attack.
Apoplexy is less frequent in summer than in the other seasons, and it is especially remarked that sudden changes of temperature are likely to be accompanied by an unusual number of cases. Changes in the arterial tension consequent upon the varying amount of blood circulating in the skin are the probable connecting link.