The Surgery of the Skull and Brain

by Louis Bathe Rawling

These theories are based on experiments carried out on the cadaver, the skull being enclosed in a tight-fitting box and subjected to pressure sufficing to bring about a fracture. Undoubtedly, the head may be compressed between two forces, as, for instance, when a person is knocked down in the street, the vehicle passing over the head, or, as in a case recently under my care, where a boy, hanging by his feet from the side of a barge, was crushed between the barge and the wharf as the vessel swung inwards with the tide. Cases of bilateral compression are, however, of infrequent occurrence, the great majority of basic fractures resulting from blows applied directly at the region of the level of the base of the skull (see [p. 76]), or from the forward propulsion of the body, the head coming into violent contact with a resisting object, as, for instance, when a person is thrown out from a motor-car, the head striking against a tree, brick wall, &c. In the first case, there can be no question of bilateral compression, and in the second the compression is exerted between the vertex and the occipital condyloid region.

Moreover, the fundamental points on which the bursting and compression theories are grounded are based on erroneous principles. The skull cannot in any sense be regarded as a sphere, nor does it possess the requisite elasticity to bulge and allow of compression in the manner that the theory demands. The skull, in reality, forms rather less than two-thirds of a sphere, the base passing inwards from the lower limits of this partial sphere in a more or less horizontal plane. This can be readily verified by placing the skull on a table so that its base corresponds to the surface of the table. The elastic properties of the skull have also been greatly exaggerated, and far too little attention has been paid to the peculiar anatomical formation of the base.

(c) The contre-coup theories.

Fractures of the base occasionally occur in which evidence is conclusive that the blow was received on the vault, the vault itself remaining uninjured. Such cases have given origin to this theory, one stating that ‘from the point struck a wave is transmitted through the semi-fluid brain, producing a fracture at some more distant point’. Helferich, for instance, maintains that isolated fractures of the orbital roof, and more rarely of other parts of the base, are produced by the influence of hydrostatic pressure. There can be no question that waves are transmitted through the brain and cerebro-spinal fluid, but that such waves should be capable of producing a basic fracture is, in my opinion, beyond the bounds of possibility. The theory is opposed to all my experience of basic fractures, and the cases brought forward in support are capable of a much more probable explanation. The base is undoubtedly the weakest part of the skull, and a blow on the vault may fail to produce a local lesion and yet, when the force is transmitted to the weaker base, may there bring about a more definite result. For instance, it is by no means uncommon to find that a blow on the frontal region fails to fracture the vertical plate of that bone and yet suffices to produce a fracture, often comminuted, of the orbital plate of the frontal bone or of the cribriform plate of the ethmoid, two fragile plates, either of which may shatter like a plate of glass from the effect of forces transmitted across them. In further support of this theory, the following case, recently under my care, may be cited. The patient received a heavy blow over the left occipital region. A fracture passed inwards across the left cerebellar fossa towards the posterior border of the foramen magnum, and a second fracture, entirely distinct from the first, passed across the right orbital plate of the frontal bone. In this case, the force conducted across the base, from behind forwards, failed to fracture the strong basi-occiput, but succeeded in producing a more definite lesion on reaching the fragile orbital plate.

Some of the celebrated surgeons of the last century insisted that the course pursued by basic fractures was to be explained on anatomical grounds, but their views have been neglected and theories based on experimental evidence have been accepted in their place. All experiments, such as those previously mentioned, are useless, and definite conclusions can only be gained by carrying out in every case the following method of investigation: (1) by obtaining in the first case an accurate history as to the manner in which the injury was received; (2) by noting all visible and palpable signs of external injury; (3) by careful observation of all the clinical symptoms during the progress of the case; (4) by comparison of such with the lesions found in case of death.

Over 300 cases have been investigated by me after these principles. In about 30 per cent. of the cases sufficient evidence was obtained to show that the basic fracture resulted and extended from a primary fracture of the vault. These cases were to be explained by Aran’s theory of irradiation. This theory, however, errs in stating further that the fracture follows the shortest anatomical route to the base. This is not correct, for the line of fracture corresponds to the direction of the applied force and is influenced to a very large extent by the resistance offered, the weaker areas being picked out and the strong buttresses avoided. It is only in the most severe cases that the fracture travels to and traverses across the base in such a direction as to show that, for the time being, all laws are in abeyance.

In about 5 per cent. of cases the fracture resulted from bilateral compression, from falls on to the buttocks, &c., and from blows applied to the angle of the jaw. These cases afforded examples of the bursting and compression theories.

On the other hand, in over 60 per cent. of cases, the injury was received over one of the following situations: (1) in front, over the frontal eminence or supra-orbital ridges; (2) in the antero-lateral region, over the external angular frontal process; (3) in the lateral region, over the lower temporal, auricular, and mastoid regions; (4) in the posterior region, over the superior curved line of the occipital bone or over the external occipital protuberance.

In all these cases, therefore, the blow was inflicted at or near the level of the base of the skull, the resultant fracture being a fracture by direct violence, the fracture traversing the base and splitting it much in the same way as a chisel splits a board of wood. The ‘grain’ of the wood may be regarded as representing the weaker basic lines, and any ‘knot’ the resistance offered by the strong basic buttresses, the forces being momentarily turned aside, but soon again passing onwards, parallel to the original direction, but not necessarily in the same straight line.