Neurosurgical Management of Skull Fractures and Intracranial Hemorrhage

Joshua M. Rosenow

SKULL FRACTURES

General Principles

Epidemiology

There are more than 2.5 million brain injuries in the United States annually, with approximately one-third sustaining a skull fracture from the injury [1].

Classification

Pattern

• Linear—A simple, straight single fracture line.

• Complex or comminuted—Multiple intersecting or radiating fracture lines.

• Nondisplaced—The fractured sections of skull are separated by the fracture line but still aligned.

• Displaced (A.K.A. Depressed)—The fractured sections of skull are misaligned by a variable distance. The thickness of the skull is often the defining distance for denoting the displacement as clinically significant.

• Diastatic—The fracture traverses and separates one of the cranial sutures.

Scalp integrity

• Closed—There is no connection between the fracture and the atmosphere.

• Open—The scalp overlying the fracture has been lacerated to such an extent as to expose the fracture to the atmosphere.

• Skull base fracture—Involves the bones of the skull base, rather than the cranial vault. These bones include the sphenoid, temporal, and occipital bones, as well as the clivus and orbital roof.

• Open depressed fractures expose the patient to an increased risk of intracranial infection and cerebrospinal fluid (CSF) leak due to the chance of a dural tear caused by the depressed fragment. This results in a communication between the intradural space and the atmosphere.

Etiology

Blunt trauma is the most common etiology. The topography of the fracture is dependent on the force of the injury and the surface against which the skull strikes. Striking the skull against a smaller surface increases the force per unit area, thus increasing the chance of a complex and/or depressed skull fracture. Skull fractures may also be caused by penetrating injuries such as projectiles (bullets, commonly), and other sharp objects driven through the skull.

Diagnosis

Clinical Presentation/Symptoms/Physical Examination

• Asymptomatic—this is the most common presentation of a skull fracture, especially closed, linear, nondisplaced fractures.

• Arterial epidural hemorrhage—Fracture lines may cross the paths of major dural arteries such as the middle meningeal artery (MMA). This causes epidural arterial hemorrhage that may rapidly expand and cause significant neurologic deficit, including cerebral herniation. Evacuation of the hemorrhage and coagulation of the bleeding point is often indicated.

• Venous epidural hemorrhage—Fracture lines may cross the paths of major venous sinuses, such as the transverse sinus or superior sagittal sinus. These are high-flow spaces between dural leaves; sinus lacerations can result in substantial hemorrhage. Occipital fractures that cross the transverse sinus can result in epidural hemorrhage in the posterior fossa.

• Carotid injury—The traumatic force sustained by the skull can not only cause bony fractures but can also lead to injury of intracranial vessels due to transmission of this force to the vessels. For example, fractures of the temporal bone that extend across the carotid canal or clival fractures involving the cavernous sinus may lead to carotid dissection and pseudoaneurysm formation [2]. Carotid-cavernous fistulas (CCFs) may also be formed. These may present with pulsatile exophthalmos.

• Cranial nerve (CN) deficits—Basal skull fractures crossing the course of CNs may lead to specific deficits as follows:

Olfactory nerve (CN I) injury—Although the olfactory nerve may be injured simply by shear injury without a concomitant skull fracture, disruption of the cribriform plate will also result in loss of olfaction because of shearing off of the olfactory processes that extend through the anterior skull base into the upper nasal cavity.

Optic nerve (CN II) injury—Anterior skull base and orbital fractures. Clival fractures may result in midline optic chiasm injury causing bitemporal hemianopia.

Oculomotor nerve (CN III) injury—Skull base fractures across the cavernous sinus.

Abducens nerve (CN VI) injury—Clival fractures.

Facial nerve (CN VII), auditory nerve (CN VIII)—peripheral-pattern facial weakness, dry eye, and hearing loss—temporal bone fractures.

Glossopharyngeal nerve (CN IX), vagus nerve (CN X), spinal accessory nerve (CN XI)—dysphagia, hoarseness, weakness of trapezius—posterior fossa fractures through the jugular foramen.

Hypoglossal nerve (CN XII)—weakness of tongue protrusion—fractures through the occipital condyle and foramen magnum.

• CSF leak

CSF rhinorrhea—anterior skull base pathology such as fractures of the cribriform plate or frontal sinus with associated dural tear. Fractures of the temporal bone with an associated dural tear may also lead to CSF flow down the nasopharynx via the Eustachian tube.

CSF otorrhea—temporal bone fracture and overlying dural tear leading to CSF egress via ear if the tympanic membrane is violated.

CSF leakage may lead to the development of meningitis [3].

• Open fractures may present with obvious signs of displaced/protruding skull pieces with or without CSF leakage.

• Encephalocele—If the fracture defect is large enough and there is an adjacent associated dural tear, a portion of the brain may herniate through the defects. This may be associated with CSF leakage but this is not always present.

Anterior skull base—encephaloceles may involve the orbit or ethmoid sinuses.

Temporal bone—brain may protrude into the mastoid air cells.

• External signs of hemorrhage

Battle’s sign (ecchymosis in the mastoid region) or hemotympanum because of temporal bone fracture.

Raccoon eyes—periorbital ecchymosis due to anterior skull base fracture.

Radiographic Evaluation

• X-rays—These identify fractures very well, but have been largely replaced by computed tomography (CT) scan [4].

• CT scan—Best, most rapid study to define the morphology of a skull fracture, its relationship to the underlying brain and venous sinuses, and to evaluate for associated hemorrhage.

Specific Circumstances Requiring Special Evaluation

• Fractures across venous sinuses—CT venography may be considered if concern for sinus occlusion is present.

• Fractures through the carotid canal or midline sphenoid bone (cavernous carotid)—CT angiography is useful for identifying vascular dissection.

• If there is suspicion of CCF—CT angiography may help diagnose this but ultimately catheter angiography will be needed to definitively identify the site of arterial injury.

• “Growing skull fractures” in children [5–7]—Otherwise known as posttraumatic leptomeningeal cysts. These are seen in fewer than 1% of pediatric skull fractures and present as an enlarging scalp mass. They result from a dural tear that allows the arachnoid to progressively herniate through the fracture defect. Secure dural closure is required.

Treatment

Guiding Principles

The assessment of the patient with a skull fracture should be directed toward assessing any neurologic injury from the originating trauma, as well as assessing the extent of the fracture and then devising a management plan.

• Simple linear fractures—These are managed conservatively.

• Indications for surgery—Open and depressed fractures:

Depression greater than the thickness of the skull

Open depressed fracture

Obvious CSF leakage

Neurologic deficit due to cerebral compression from fractured segment

Frontal sinus fractures with displacement of the inner table and/or fractures of both the inner and outer tables may be considered for cranialization of the sinus with exenteration of sinus contents and packing of the frontonasal ducts. This is done to prevent the development of a mucocele with epidural extension and resulting abscess.