The conditions under which it occurs may not vary greatly from those of the more ordinary intracerebral effusion. In two instances under the observation of the writer the source of hemorrhage has been a vessel of small, but not the smallest, calibre (artery), situated near the fissure of Sylvius, in the lower parietal or temporo-occipital lobe. In children meningeal hemorrhage is, with only a few exceptions, the usual lesion of apoplexy. The blood is usually dark and coagulated in recent cases. Blood found under the membranes where no fracture has taken place is, however, more likely to have been derived from the brain-substance and to form part of a cerebral hemorrhage.
Hemorrhagic pachymeningitis, indicated by a layer of fibrin included between the dura on the one hand and a false membrane on the other, is met with in connection with meningeal and cerebral hemorrhages. It is supposed to depend on a small and thin hemorrhage upon the surface of the brain, which forms, by its irritant action, a false membrane about itself. It is found usually over the vertex.
Hemorrhage into the ventricles is nearly always the consequence of a hemorrhage in the brain-substance breaking through, although it may in rare cases originate in the vessels of the choroid plexus, velum interpositum, or meninges. Its source, however, is sometimes so near the surface as to cause but little laceration of the cerebral tissue. The blood breaking into any one of the ventricles may be found in one or all of them (except the fifth), and form quite an accurate cast of their shape.
The most common form of intracranial hemorrhage, however, which most nearly concerns us here, and which is generally meant when sanguineous apoplexy is spoken of, has its principal seat in the brain itself, which is, of course, more or less lacerated. Such hemorrhages may vary greatly in size, from a mere red point (punctate or capillary), of which many may be present at once, to one of many ounces, filling a large cavity of nearly the length of one hemisphere, and pushing the torn and compressed brain-substance before it in every direction. The amount of laceration produced of course varies greatly; sometimes it seems as if nothing more than a pushing aside of fibres without rupture had taken place, while at others large masses of tissue are torn away and mixed up with the blood into a pulp.
In a recent hemorrhage the clot itself, speaking of those of a size above the capillary, is usually homogeneous, the brain-substance surrounding it ragged, œdematous, yellowish or red, and frequently containing many minute secondary hemorrhages. The rest of the brain is frequently found anæmic from pressure, the convolutions flattened, the surface dry, and the section exhibiting a diminished quantity of blood. In older cases, however, and probably also in some where atrophy, senile or otherwise, has preceded the hemorrhage, this condition is not found, and we may have the convolutions shrunken and the meshes of the pia containing an excess of serum.
If death does not take place speedily, the clot undergoes degenerative changes. Its color becomes somewhat lighter, chocolate color, reddish-yellow, or yellowish-red. A portion is absorbed, and after a time the cerebral substance in the neighborhood forms about it a wall of some density, so that finally nothing is left but a cyst with fluid or semifluid contents, and often remains of connective tissue. Sometimes the absorption of a clot of moderate size is so complete that only a firm mass of a reddish or yellowish-brown color marks the seat of an old hemorrhage. The brain-substance in the neighborhood may be more or less atrophied, and a distinct depression may be noted over the position. The microscope shows in a fresh hemorrhage only broken-down nerve-tissue and blood and vessels more or less degenerated. In an older one the blood-corpuscles have disappeared, but masses of pigment of a dark yellow or a brownish-red remain to show the former presence of blood. This pigment occurs in the form of rounded granules or of small rhombic crystals, and has received the name of hæmatoidin. The light-yellow masses often found along the course of the cerebral vessels are not evidence of hemorrhage, but of congestion merely. The so-called inflammation or granulation corpuscles, which are simply the fattily degenerated cells of the organ in which they are found, and which usually possess no distinctive form, being simply round masses of fat-drops, are often met with in the brain in hemorrhage or softening. It is sometimes perfectly evident, however, from their form, triangular or pyramidal, that they are degenerated nerve-cells. The blood-vessels, those just above the size of capillaries, are usually in a condition of fatty degeneration, masses of dark granules occupying more or less densely the line of their walls. A mere deposit of fatty granules inside the perivascular sheath, but outside of and not involving the walls of the arteries, may present the appearance of a degeneration of the walls themselves. This condition may be a consequence of any lesion involving degeneration of brain-tissue, and in no way a cause.
The intermediate stages of transformation in a hemorrhage are less frequently found than the recent or old ones, since the patient, if he does not die within a few days, is likely to live for some weeks or months.
The changes taking place in the clot itself within the first few days are not very marked, but the walls of the cavity may become softer and more deeply colored, at first red and afterward yellow. Blood-crystals have been detected on the seventeenth day (Virchow). The following descriptions have been given of clots of different ages: Eleven days—reddish-yellow softening clot, with brain-tissue stained for half an inch in depth, and brain rather hard in vicinity. Eighteen days—cavity with its edges anteriorly and superiorly sharply defined, with the edges posteriorly ragged and yellowish, filled with a tolerably firm brick-red mass adherent to surrounding brain, and showing in the centre a softened clot about the size of a pea. Twenty-eight to thirty-five days—soft, brownish, and semifluid. Forty-one days—spot of softening filled with brownish material. One hundred days—somewhat darker, and a little more distinctly marked from surrounding tissues; by microscope granular corpuscles, groups of fatty granules along the swollen vessels, granules of pigment. Eighty-three years—old hemorrhagic focus in right optic thalamus, color yellowish, and areolar structure.
The thirtieth day is given as about the time at which the walls of the cyst become more firm and distinct. The following statement is prepared from a considerable number of cases given by Durand-Fardel: From four to six weeks, the clot is dark-colored, from black to ochrey or reddish-yellow. It varies in firmness. The capsule is tolerably firm. From two to four months, it seems to be generally softer, pultaceous, grumous, or the clot still remaining swimming in serum; in some cases lighter in color. In six months it has lost more in color, and the cavity may be smaller. In a year there is still considerable color left. In a few cases after some years the blood has been found in the form of a dried mass, not changed or darker in color.