Even when every allowance is made for the fact that operative measures were adopted in the more hopeful cases, the above statistics show conclusively that early operation affords great hope of cure.
Fig. 53. A Basic Fracture with Laceration of both Carotid Arteries.
Before passing on to subdural hæmorrhage, it will be convenient to discuss briefly the question of injury to the internal carotid artery.
This vessel, during its forward passage in the outer wall of the cavernous sinus, from the posterior to the anterior clinoid processes, crosses the line of the typical middle fossa fracture (see [p. 84]). The artery is loosely embedded in the sinus, it is protected by the third, fourth, ophthalmic division of the fifth and sixth nerves, and it is situated some distance above the level of the base of the skull. In spite of this degree of protection from injury, the artery may be lacerated in this part of its intracranial passage. The basic fracture is necessarily of a very severe nature. Two cases have come under my own care: one in which both arteries were torn across, the fracture passing from one middle fossa to the other, with such wide separation of the anterior and posterior segments of the skull that the two were freely movable on one another ([Fig. 53]), whilst in the second case, the fracture, originating in the left frontal region, passed backwards across the anterior fossa, comminuting the base in the region of the cavernous sinus, lacerating that sinus and tearing the artery ([Fig. 54]).
Fig. 54. A Basic Fracture with Laceration of the Cavernous Sinus. A, The optic nerve; B, The cavernous sinus; C, The third nerve; D, The internal carotid artery.
In both cases death was almost instantaneous, blood pouring from the nose and mouth.
In some few cases the vascular lesion is confined to a minute tear in the coats of the vessel, a fistulous communication being formed between the artery and the cavernous sinus—arterio-venous aneurysm. This condition is discussed on [p. 204].