Fig. 72.—Perforating Fracture of Frontal Bone from within Separation of plate outer table. (Low velocity.) 1/2

The injury to the cranial contents varied with the degree of bone injury. Hæmorrhage on the surface of the dura may in rare instances have been the sole gross lesion; I never met with such a condition, however. In all the cases in which comminution had occurred, some laceration of the dura, even if not more than surface damage or a punctiform opening, had resulted. In the more serious gutter fractures an elongated rent of some extent usually existed. In the perforating fractures two more or less irregular openings were the rule. The amount of hæmorrhage, even if the venous sinuses were implicated, was on the whole surprisingly small, when the cases were such as to survive the injury long enough to be brought to the Field hospital. I never saw a typical case of middle meningeal hæmorrhage, although many fractures crossing the line of distribution of the large branches came under observation. Case 60, p. 274, illustrated the fact that the osseous lesions of lesser apparent degree are sometimes the more to be feared in the matter of hæmorrhage, as compression is more readily developed.

The degree of injury to the brain depended on the depth of the track, the resistance offered by the bones of any individual skull, the weight of the patient, but chiefly on the degree of velocity retained by the bullet. It was sometimes slight and local as far as symptoms would guide us; but in the majority of cases out of all proportion to the apparent bone lesion, if the range was at all a short one. Cases illustrative of these injuries are included under the heading of symptoms.

It will be, of course, appreciated that the coarse brain lesions under the third heading differed in localisation and in extent alone, and in no wise in nature, from those observed in the two preceding classes. The damage consisted in direct superficial laceration and contusion, and beyond the limits of the area of actual destruction, abundant parenchymatous hæmorrhages more or less broke up the structure of the brain, such hæmorrhages decreasing both in size and number as macroscopically uninjured tissue was reached. No opportunity was ever afforded of examining a simple wound track in a case in which no obvious cerebral symptoms had been present.

IV. Fractures of the base.—In addition to the above classes, a few words ought to be added regarding the gunshot fractures of the base of the skull. These possessed some striking peculiarities; first in the fact that they might occur in any position, and hence differed from the typically coursing 'bursting' fractures we are accustomed to in civil life as the consequence of blows and falls, and consequently were often present without any of the classical symptoms by which we are accustomed to locate such fissures. Secondly, the peculiar form was not uncommon in which extensive mischief was produced from within by direct contact of a passing bullet.

As far as could be judged from clinical symptoms, indirect fractures of the base such as we are accustomed to meet in civil practice in connection with fractures of the vault were decidedly rare, and, as has already been mentioned, ocular evidence of extensive fissures extending from perforating wounds of the vertex was wanting, except in the extreme cases classed under heading I. For these reasons I am inclined to regard them as uncommon.

Direct fractures of the base, on the other hand, were of common occurrence, especially in the anterior fossa of the skull. These might be produced either from within, the most characteristic form of gunshot injury, or from without. The fractures from within were often simple punctures of the roof of the orbit or nose.

Punctured fractures of the roof of the orbit caused little trouble as far as the cranium was concerned, but the orbital structures often suffered severely. I saw one or two very severe comminutions of the roof of the orbit caused by bullets which had crossed the interior of the skull; in one case the whole roof was in small fragments, while the damage in others was not greater than chipping off some portion of the lesser wing of the sphenoid. The roof of the orbit again was sometimes very severely damaged by bullets which first traversed that cavity itself; thus in one case which recovered, the bullet passed transversely, smashing both globes, and fracturing the roof of both orbits and the cribriform plate so severely as to lacerate both dura-mater and brain, portions of the latter being found in the orbit on removal of the damaged eyes.

Fractures of the middle and posterior fossæ were met with far less frequently, partly I think because vertical wounds passing from the vertex to the base in these regions were with few exceptions rapidly fatal, and partly from the fact that the occipital region, being ordinarily sheltered from the line of fire, was rarely exposed to the danger of direct fracture from without. As an odd coincidence I may mention that in my whole experience during the war I only once saw bleeding from the ear as a sign of fracture of the base, apart from direct injuries to the tympanum or external auditory meatus.

Symptoms of fracture of the skull, with concurrent injury to the brain.—These consisted in various combinations of the groups of signs indicative of the conditions of concussion, compression, cerebral irritation, or destruction. Although the symptoms possessed no inherent peculiarities, yet certain characteristics exhibited served to illustrate the fact that, as a result of the special mechanism of causation of the injuries, the type deviated in many ways from that accompanying the corresponding injuries of civil practice.