The Cephalhematoma is constantly circumscribed near the margin of the affected bone, and does not pass beyond the sutures.

It is a circumstance of considerable importance, though it has hitherto been almost unnoticed, that in very many cases in which there is a collection of blood on the outer surface of the skull, there is also a corresponding extravasation between its inner surface and the dura mater. The inner accumulation is, as a general rule, the less extensive; but there are cases in which the reverse is the fact. Of course, if a bone be laid bare in this manner on both sides for a length of time, the prognosis is unfavorable.

Cephalhematoma originally is nothing more than an accumulation of blood beneath the pericranium: there is no essential anomaly either in that membrane or on the bone: most of the blood is usually loosely coagulated, and is of a blackish-red color: and a pale-red fibrinous coagulum, stained with the coloring matter of the blood, frequently adheres to the inner surface of the pericranium, and to the bone.

The Examination Of A Recent Thrombus

The Examination Of A Recent Thrombus is of itself sufficient to determine as to the truth or error of various statements and opinions that have been put forth, according to which cephalhsematoma arises from certain anomalies in the development and texture of the bone, and to settle the true nature of the disease and the source of the bleeding. Most of the hypotheses have been based upon examinations made at late periods of the disease, so that following in our description the course of the disease, we shall come in succession upon the various appearances which have been detailed, and which, though correctly observed, have been erroneously interpreted.

When the cephalhematoma has existed a short time, appearances are presented precisely similar to those that follow any separation between a bone and its periosteum. An inflammatory process commences, at the margins of the denuded part, and bony matter is deposited in the form of a velvety and finely filamentous osteophyte. The osteophyte extends to a breadth of several lines beyond where the pericranium and the bone remain connected, but it is thickest just at the margin, and there forms an elevation, which rises abruptly around the denuded surface, but externally is gradually bevelled off. This exudation is what has been much spoken of as the bony margin of the cephalhsematoma, and until quite recently was erroneously regarded as proving some original deficiency, or some loss from disease, of the outer layer of the bone at the base of the cephalhgematoma. Upon the exposed bone, and inner surface of the pericranium, a fluid next exudes, which is at first gelatinous, but gradually becomes more dense; and it may be observed that the bony margin, just spoken of, becomes continuous with the layer of exudation that adheres to the pericranium, while, at the base of the tumor, it meets that which covers the bone.

Should the extravasated blood be removed by absorption, or evacuated by an artificial opening in the tumor, the pericranium and bone unite together in a simple manner by means of the exudation. But if this do not occur, a very remarkable appearance is presented in a few cases, - few, inasmuch as thenceforward the inflammation usually becomes suppurative. The layers of exudation covering the bone and the pericranium gradually ossify. The denuded surface of the bone and the inner aspect of the pericranium are then each covered with a very delicate and finely reticulated osseous stratum, and the extravasated blood is enclosed between them, and altered to a dirty or rusty brown color. The ossification of both layers of the exudation is sometimes limited to particular spots, and sometimes partial ossification is met with only on that layer which lines the pericranium. In the latter case, plates of bone are found scattered over the surface of the tumor. The sanguineous tumor then exhibits a certain firmness, a kind of rigidity of its walls, and when firmly pressed gives an impression of crepitation like the crackling of parchment. This state of parts may lead to the error, that the outer table has separated from the bone, and adheres to the pericranium.

Far more frequently, when the swelling is not opened and its contents evacuated, the inflammation becomes suppurative, the extravasation changes to a chocolate brown, discolored, fluid pulp, and ulceration or caries, and partial necrosis ensue. The pericranium is attacked with a similar inflammatory process, its inner surface is covered with purulent matter, and the bone becomes rough, unevenly exfoliated, and worm-eaten, and its pores and grooves enlarge.

If the tumor, when in this state, be not opened artificially, or if the pericranium and the other soft parts above it do not ulcerate and make a spontaneous opening in it, the caries which has already commenced at the denuded surface of the bone extends more deeply, an effusion of pus takes place beneath and loosens the dura mater, and at length the bone perishes in its whole thickness. Generally, when this takes place, the pericranium, and the soft integuments covering it, suppurate extensively, and become discolored and easily lacerable. At such a stage as this, cephalhaematoma generally proves fatal, sometimes by exhausting the strength, but more frequently by the extension of inflammation to the dura mater and inner membranes, and to the brain itself. The fatal result is occasionally brought about by purulent matter being taken into the circulation, and by consequent pyaemia and metastasis.

But even when cephalhaematoma has reached these advanced stages, a cure is sometimes effected. Healthy suppuration succeeds the evacuation of its contents, and the pericranium unites with the exposed surface of bone through the intervention of a layer of granulations, which afterwards ossifies. The portion of bone which the cephalhematoma occupied appears for a long time enlarged, thicker than natural, and somewhat uneven on its external surface, but in process of time this disappears. Even when an extension of suppuration here and there through the bone, and an effusion of purulent matter upon the dura mater, have produced necrosis, and a portion of bone has exfoliated, repair may take place; for granulations arise from the healthy bone which cover the dura mater, and uniting with those that spring from the pericranium, become a basement in which new bone is formed both at the margin of the opening and at other isolated spots.

When there is an effusion of blood upon the dura mater, as well as beneath the pericranium, the exposure of the bone on both sides renders the prognosis of course unfavorable, and the more so in proportion to the extent of the effusions.

Thus, then, cephalhematoma consists of an effusion of blood between a cranial bone and its pericranium, and frequently, at the same time, between the bone and its internal covering of dura mater also; and the source of the bleeding is the delicate bloodvessels which pass from those membranes upon and into the bone, and which have been ruptured.

Any essential anomaly in the development of the bone, or morbid affection of its texture, is merely an occasional and exceptional occurrence: the principal anomaly, when any does occur, is that isolated spots of the bone affected with cephalhematoma, or of some of the other bones composing the cranial vault, are thinner and softer than natural.

In a recent cephalhematoma, however, a manifest congestion of the bones of the skull is pretty constantly observed, and thin strata of extravasated blood may be noticed beneath the pericranium, near it. There is no question that the final rupture of the vessels is due to this congestion; and it is the more certain, from the fact that in ordinary cases there is no other abnormal appearance to which the hemorrhage could be attributed. Moreover, the bone beneath the extravasated blood appears pale, especially when there is an effusion also on the dura mater; and this results from the emptiness of its vessels.

It is an interesting circumstance, that cephalhematoma sometimes coexists with effusions of blood between tissues, that have the same relation to each other as bone and periosteum. Thus peripheral apoplexy of a congested liver, or an extravasation of blood beneath its peritoneal investment, is not an unfrequent accompaniment of cephalhematoma.

In the great majority of cases, cephalhematoma most probably commences during birth, and increases to a palpable tumor soon afterwards. But instances do occur, in which the swelling is not perceptible till several days after birth; and there is nothing against the opinion, that it may form on the skull subsequently to the birth of the child. Its duration may extend over three or four months, or more.

It is most frequently found in first-born children.