Skull Injuries

Before the introduction of computed tomography (CT) scans, plain skull radiographs were of vital importance in evaluating patients with head injuries. The presence of a skull fracture strongly suggested the possibility of a significant, underlying intracranial injury. Fracture is present in 66% to 100% of patients with epidural hematoma; 18% to 60% with acute subdural hematoma; and 40% to 80% with contusions or intracerebral hematoma. Such intracranial injuries are now immediately identified by CT, and an associated skull fracture is often noticed only in passing.

There are, however, several types of skull fracture that are of clinical significance. The most classic is the basilar skull fracture, which may be associated with cerebrospinal fluid (CSF) leak and cranial nerve injuries. Basilar skull fracture has been reported in up to 25% of patients sustaining a head injury. Even with CT, basilar skull fractures may not be identified because of their orientation to the plane of the scan. Special thin cuts or coronal views may be required. The majority of basilar skull fractures occur through the petrous bone or the anterior cranial fossa. Clival fractures are less common. Petrous bone fractures occur either transversely or longitudinally, and their orientation predisposes to various complications.

The classic clinical presentation of a petrous bone fracture is with the Battle sign—a retromastoid hematoma. Raccoon eyes—periorbital hematomas—may be seen with anterior skull base fractures. CSF leaks, otorrhea or rhinorrhea, have been reported in approximately 10% of patients with basal skull fractures. Otorrhea is typically associated with petrous fractures, whereas rhinorrhea may emanate from either frontal fossa fractures through the cribriform plate or the petrous bone through the eustachian canal. In either case, with bed rest and head elevation, the CSF leak ceases spontaneously in more than 85% of patients. The administration of antibiotics is not advised because this may predispose to antibiotic-resistant infection. Persisting leaks may be treated with a lumbar drain; only a small number require direct or endoscopic surgical repair.

If there is any question as to whether drainage from the nose or ear represents CSF, the fluid can be checked for glucose, which typically is greater than 30 mg/mL in CSF, or β-2-transferrin, which is found only in the CSF.

Cranial nerve injuries may complicate up to 5% of basal skull fractures, the most common of which is facial nerve injury in association with petrous fractures. Such an injury may occur in up to 50% of patients with transverse and 20% with longitudinal fractures. The facial nerve is especially prone to injury in the narrow fallopian canal as swelling occurs or by compression from fracture fragments. If facial paralysis is immediate and complete, the chances of recovery are small. More minor injuries tend to recover well, and steroids are often used for treatment. Some advocate early surgical exploration and decompression of the nerve.

Two other types of skull fractures require specific clinical management: open depressed and frontal sinus fractures.

Open, or compound, depressed skull fractures have been said to be associated with infection and post-traumatic epilepsy. They definitely are associated with potentially significant underlying brain injury. Common practice until recently was to operate on all such fractures. Contemporary literature, however, has shown that the risk of post-traumatic epilepsy is not significantly increased, and the risk of infection may be greater in those patients treated operatively than nonoperatively. It thus appears possible to manage conservatively all but the most contaminated and comminuted fractures with reasonable safety.

The primary concern over frontal sinus fractures is the status of the posterior wall of the sinus, with the possibility of dural violation and the risk of CSF leak, pneumocephalus, and infection. As a general rule, unless there is overt evidence of CSF leak or pneumocephalus with posterior wall fragments in-driven more than 3 to 4 mm, nonoperative management is usually successful. Some, however, advocate surgery on the majority of frontal sinus fractures to prevent the development of a mucocele.

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