| Andral: Beginning of softening in 27 cases. | Andral: Death with softening in 153 cases. | Cases (with autopsies) of embolism, thrombosis, and softening—25 cases. |
| 17–20 4 27 2 30–37 2 43–45 2 53–59 4 63–69 7 76–78 6 | 15–20 10 20–30 18 30–40 11 40–50 19 50–60 27 60–70 34 70–80 30 80–89 4 | 20–30 4 30–40 3 40–50 3 50–60 1 60–70 5 70–80 2 Young 1 Middle-aged 1 Old 5 |
In the etiology of cerebral arterial thrombus there seem to be two factors of prime importance, although there are cases which seem to demand a third, and Charcot32 suggests the possibility of some hæmic dyscrasia favoring the formation of a thrombus, and relates a case of thrombosis of the middle cerebral, with three others of the same process in other arteries, occurring in patients with uterine cancer, where all the usual sources of emboli were explored with negative results. The first of the two is disease of the cerebral arteries, not necessarily extensive, but sufficient to form a starting-point on the inner wall for the deposit of fibrin. In this respect the etiology of thrombosis may be various. Syphilitic endarteritis, for instance, may very easily give rise to this lesion, but it is likely to be accompanied by others, and has a symptomatology more or less peculiar to itself. It is not, of course, to be included with the form we are considering.
32 Comptes Rendus Soc. de Biol., 1865, p. 24.
The second factor—one which is perhaps capable of giving rise to coagulation of the blood or deposit of fibrin without any arterial disease—is weakness of the heart, connected or not with anæmia. The causes of this condition may be manifold, and are likely to lead to many other consequences than cerebral thrombosis. A thrombus may form upon a very small basis of atheroma. Several of these points are illustrated in the following case: A lady, aged about sixty-five, had had for many months vague symptoms of want of strength, fatigue, want of appetite, and so on, with complaints of distress and fulness in the abdomen, for which no special cause could be found. On one occasion she was unusually long in dressing, and her expression was noticed to be changed and her voice altered for a few moments. The pulse was habitually 60 or less, and at times irregular, but nothing abnormal could be detected in the sounds or position of the heart. Fatty degeneration was suspected. One morning, after going to bed in her usual health, she was found on the floor of her room unconscious and with left hemiplegia. She lived about thirty-six hours. The autopsy showed nothing abnormal in the abdomen except a considerable accumulation of fat; and in the thorax the heart appeared normal, and was not fatty. There was very little atheroma. In the end of the internal carotid artery was a thrombus, of which the lower and firmest part was connected with a very small spot of roughening just at the point where the artery comes through the base of the skull. It extended just beyond the origin of the middle cerebral artery, which was of course occluded. The corresponding region of the brain was converted into a vast mass of softened tissue.
The SYMPTOMS of the lodgment of an embolus in the brain may closely resemble, or even be precisely the same as, those of hemorrhage. Unless, however, an embolus makes a pause on its journey, giving rise to a partial obstruction before there is a complete one, or unless the obstruction is not absolute until after the formation of a secondary thrombus, the attack may be absolutely sudden.
A thrombus, however, is slower in its formation, and may produce gradually increasing anæmia of the region of brain supplied before it is absolutely complete, with a gradually increasing paralysis and loss of consciousness slowly approaching. Thus we may have the early symptoms in the form of headache, vertigo, heaviness, and drowsiness, peculiar sensations in the limbs about to be paralyzed or in the head, delirium of various kinds, or hysterical manifestations. Prévost and Cotard33 lay special stress upon the importance of severe vertigo (étourdissement) as a prodrome or warning of softening, especially in the aged. It is dependent upon anæmia of the brain, and this, in its turn, upon atheroma of the arteries, and sometimes at least upon feebleness of the circulation, both of these being conditions likely to cause the deposit of a thrombus. As, however, the thrombus does not necessarily result from these conditions, and as the vertigo may arise from other sources, as stated under the head of Cerebral Hemorrhage, it is to be looked upon with special suspicion chiefly in those cases where other symptoms might lead in the same direction, and when other causes can be excluded.
33 Mémoires de la Soc. de Biol., 1865, p. 171.
The same authors also speak of less defined symptoms, like delirium and stupor, occurring among the inhabitants of the Salpêtrière (old women), with intervals of comparative health, as being premonitory.
It is possible, however, for the symptoms of thrombus to be developed rapidly when, as in the case last described, the thrombus begins to form in a place which does not entirely interrupt the current, but afterward reached the mouth of a large vessel, which it closes.
The loss of consciousness, coma, and all the phenomena of the apoplectic attack, with the possible exception of early rigidity, may be as fully developed from occlusion of the cerebral vessels as from their rupture; but it must be said that it is more common to meet with them in cases of large hemorrhage than with either embolism or thrombosis.