—The majority of basal fractures are fatal, either because of injuries to the brain, or of hemorrhage or violence along the nerve trunks, or from infection extending along the newly opened paths. Other things being equal, the longer the fissure the greater the danger, particularly so when it takes its origin in the vertex, and because of greater ease of infection. Air infection may occur in any basal fracture by fissures extending into the various air-containing cavities—nose, ears, sinuses, etc. They are then practically compound, though invisibly so. The general prognosis will depend, first, upon the injury to the cranial contents; second, upon the possibility of infection. Statistics are absolutely unreliable, although always possessing interest. Numerous museum specimens show the perfection with which bony repair may occur and the admirable way in which compensation is afforded for defects. Suppuration after basal fractures is mainly that due to purulent basal meningitis, in which case the brain symptoms dominate in the clinical picture, while the appearance of a single drop of pus in the ear or upon the surface is of the greatest significance. The conversion of a serous outflow (e. g., from the ear) into purulent fluid is also pathognomonic. Various paralyses, principally of the cranial nerves, may follow this injury and prove temporary or permanent. Diagnosis is often made by a study of these special nerve lesions.
Diagnosis.
—The most significant diagnostic features are:
1. Spread of blood from the point of fracture until it appears as an ecchymosis at certain points beneath the skin: This will occur early in some cases and late in others. It may appear beneath the skin or beneath the conjunctiva or other mucous membranes, even in the pharynx. Occurring about the mastoid, it implies fracture of the middle or posterior fossa; about the eyelids, of the anterior fossa. Beneath the bulbar conjunctiva it means extravasation along the optic sheath, probably from within the dura. In fractures of the posterior fossa it will come to the surface of the neck, but only after two or three days. The ecchymoses about the lids or orbits occurring after two or three days mean more than those occurring within these days, for the latter may be caused by external bruising. The globe of the eye may be pushed forward by blood accumulating within the orbit. Exophthalmos thus produced is therefore most significant, though not common.
2. Escape of serous fluid, blood, or brain substance from the cavities of the skull: Hemorrhages from this cause occur most often from the ear, the petrous bone being tunnelled with various canals through which blood may thus escape. The surgeon should, however, assure himself in every instance that the blood is escaping from the ear and not from some trifling wound of the external soft parts, the soft walls of the meatus, or the tympanum. Profuse hemorrhage can probably only come from a basal fracture. Escape of serous fluid is usually noted as a sequel to hemorrhage, although it may begin almost immediately after an injury. Rarely more than twenty-four hours elapse before it begins to flow. The quantity of fluid discharged is sometimes considerable. It may occur in frequent drops or during expulsive efforts, like coughing, or may ooze in such a way as to be insensibly collected by the absorbent dressings. In average cases the amount in twenty-four hours is from 100 Cc. to 200 Cc.; 800 Cc. have been noted in occasional instances, and in a very few still more. Occasionally violent expiration will increase the flow.
In some cases the fluid may escape through the Eustachian tube into the pharynx, whence it may escape by the nostrils or be swallowed.
The escape of brain substance is rarely noted, but obviously implies such serious injury as to make the prognosis of the worst.
3. Disturbance of function along particular cranial nerves, paralysis of which is often produced by fractures of the base, especially those involving the foramen of exit of the nerve involved: The nerve may be lacerated or injured in such case by the fragment of bone.
In addition to these distinctive features there will be in the majority of instances brain symptoms, either of contusion or compression, varying in severity within all possible limits, but adding their weight to the value of the testimony.
Other and unusual signs of basal fracture may occur, such as communication between the cavities of the petrous bone and the mastoid cells, leading to the formation of pneumatocele (see [page 545]), or emphysema of the overlying soft parts, observed mostly about the orbits, when the nasal cavity is involved.