A Practical Guide for Making Post-Mortem Examinations

Section I. of the Skull.

=Fracture.= In a post-mortem examination of the head, after death from a blow or fall upon that part, a fracture may be disclosed of which there was no external trace. Owing to the greater thinness and brittleness of the inner table, it is possible for this to be fractured without any corresponding injury to the external; such fracture may possibly rupture some of the branches of the meningeal arteries, which will be followed by the formation of a clot between the bone and dura mater, the pressure of which may be sufficient to produce death. Owing to the same cause—greater brittleness of the inner table—when fracture of the outer exists, that of the inner table will be likely to be more extensive, accompanied perhaps with depression, of which there is no external evidence.

Again, it will sometimes be discovered that fracture exists at a point opposite to that upon which the blow was received, on the principle of the “contre coup” of the French; thus, the blow having been received on the occiput, the fracture may be found in the frontal region; or, received on the top of the skull, fracture may result at the base. In falls from a height, upon the top of the head, the weight of the body, acting through the cervical vertebræ as a propelling force, is very likely to produce fracture of the occipital bone.

=Caries= may affect any of the bones of the head, but in the majority of cases it will be the result of syphilitic or mercurial poisoning. Following an attack of periostitis, the inflammation extends to the bone and gradually develops the carious ulceration. While the condition is usually confined to, or at least, most strongly developed upon the outer table, it may involve the entire thickness. In syphilitic ulceration of the bones of the nasal cavity, the disease may destroy the cribriform plate of the ethmoid bone, and thus extend to the membranes of the brain. So also, in caries of the petrous and mastoid portions of the temporal bone, which sometimes results from scarlet fever, the disease may extend to the inner surface, resulting in the accumulation of pus within the cranial cavity.

Along either side of the central portion of the inner surface of the calvarium may be usually seen, at least in the heads of aged persons, a number of irregular, rough pits, varying in size and depth, which are not to be mistaken for disease of the bone, they being simply impressions of the Pacchionian glands.

=Thinning= of the bones of the head will always indicate increased pressure from within, induced by hypertrophy of the brain, or, as is more frequent, hydrocephalus. In the latter case, not only thinning, but complete absorption of the parietal and other bones may result.

=Increased Thickness= will also sometimes be found. This condition indicates diminished pressure from within, as in atrophy of the brain. The thickening results from a gradual remodeling of the inner table and diploe, so that while the exterior of the skull may retain its normal size and form, the inner table following the retiring and shrinking brain, the interval between the two becomes filled with the thickened diploe. It has been observed that this hypertrophy is greatest at those parts of the bones where ossification first commences, as at the parietal and frontal eminences. It is not confined to old persons, though perhaps more frequent with them.

Section Ii. the Membranes of the Brain.

1. The Dura Mater.

This membrane, serving both as a periosteum to the inner surface of the cranial bones and as a support to a serous membrane—the reflected layer of the arachnoid—is subject to affections of a two-fold character, those peculiar to the fibrous and serous portions.

=Inflammation= of this membrane, may involve either the outer fibrous, or the inner serous layer. In the former case, the membrane appears congested, red and more or less softened. The inflammatory process may result in the formation of pus between the bone and dura mater, and even in gangrene. The disease may also extend to the adjacent portions of the pia mater and brain substance. External injuries, fractures of the bones of the skull, inflammation of the periosteum, otitis, resulting in caries of the temporal bone, may all be causes of inflammation of the outer portion of the dura mater.

Inflammation of the inner surface of this membrane, is marked by the presence of a net-work of delicate red vessels, while the surface is covered by a soft, grayish or yellow semi-purulent matter, and may attend cases of pyæmic poisoning, puerperal peritonitis, or some of the exanthemata.

=Thickening= of the fibrous portion of the dura mater may be found as a result of chronic inflammation, either spontaneous or as the result of external injury. From the identity of structure between this and other fibrous tissues of the body, it is not unlikely that this thickening is often the result of a rheumatic form of inflammation.

External violence is, however, most commonly the cause of the change. In one case, the patient fell down stairs in a state of intoxication, striking the head on the steps. He continued in a state of insensibility for nine days, when he began to show signs of returning consciousness, taking food and drink, but memory, judgment, and all the mental faculties were gone. Death ensued in about two years. The dura mater of the left hemisphere was found greatly thickened. The pia mater infiltrated with a large amount of serous fluid. The convolutions were atrophied, and about four ounces of serous fluid found in the ventricles. The fornix was softened and the septum lucidum entirely destroyed.

=Fibrinous Clots, or Thrombi=, will be occasionally found within the sinuses of the dura mater, where they may have given rise to congestion of the brain, with apoplectic effusions, paralysis, convulsions, coma, etc. They may originate from injuries of the head, inflammation of the dura mater, pulmonary disease, etc.

=Tubercular Deposits= are also sometimes found in this membrane, appearing, however, mainly upon the arachnoid surface. They present the usual character of tubercle, having a whitish or grayish appearance, with the consistence of cheese, and scattered in small particles upon the surface. They are found in tubercular meningitis, (a disease common with children but rare with adults,) and in most of those cases of so-called acute hydrocephalus.

=Tumors= of various kinds are occasionally found in the dura mater, including cystic, fibrous, fatty, osseous and cancerous growths. The latter may cause such absorption of the bones of the skull, as to appear on the exterior of the head.

In one case which came into the dissecting-room some years ago, thin bony formations of the size of a silver quarter dollar were found in the tentorium, and smaller ones in the falx cerebri. Nothing could be learned of the previous history of the case.

2. Arachnoid and Pia Mater.

As morbid conditions of the arachnoid membrane are more common with its visceral layer, and as these conditions usually involve the pia mater, the two membranes are here noticed together. They will be found presenting various degrees of congestion after death, which will not necessarily be a positive indication of the extent of congestion during life.

=Pacchionian Bodies.= Along either side of the great fissure may be noticed within the pia mater of adults, several small white bodies, varying in number and size—the Pacchionian bodies. They may cause absorption and perforation of the dura mater, and even of the bones of the skull. Being looked upon as the result of mere senile changes, they do not indicate the presence of disease, though repeated congestions of the brain appear to favor their more rapid development.

=Inflammation= of these membranes, or meningitis, is a very common affection, and is accompanied with an accumulation within its substance or beneath its layers, of serum, lymph, or fibrine in various proportions. It may be confined to circumscribed portions, or involve a large portion of the membrane, and even extend to the spinal cord. Adhesions between the two surfaces of the arachnoid sometimes result from this form of inflammation.

Insanity in its various forms is most frequently accompanied with some morbid condition of these membranes. In twenty-two cases of insane persons whose brains were inspected by Dr. Marshall, in twenty-one, serous fluid, varying in amount from one to twelve ounces, was found in the ventricles, and in seventeen of these twenty-one cases, similar effusion was found in the sub-arachnoid space, or within the substance of the pia mater. While red injection of the membrane was found only in four cases, yet other conditions—the effusions, &c.—were evidently the result of previous inflammation. In nine cases were the arteries of the brain opaque, thickened, steatomatous, or ossified; conditions highly favorable for deranging the capillary circulation of the membranes or of the brain.

The following statement gives the principal morbid changes of these membranes which have been found in cases of insanity:

1. Injection, more or less intense, of the pia mater, giving a red or scarlet appearance; or, where infiltrated with serous fluid, presenting a pale gray color and increased in thickness.

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