Basilar Skull Fracture

Article Author:
Leslie Simon
Article Editor:
Edward Newton
Updated:
11/18/2018 12:32:54 PM
PubMed Link:
Basilar Skull Fracture

Introduction

Basilar skull fractures, usually caused by substantial blunt force trauma, involve at least one of the bones that compose the base of the skull. Basilar skull fractures most commonly involve the temporal bones but may involve the occipital, sphenoid, ethmoid and the orbital plate of the frontal bone as well. Several clinical exam findings highly predictive of basilar skull fractures include hemotympanum, cerebrospinal fluid (CSF) otorrhea or rhinorrhea, Battle’s sign (retroauricular or mastoid ecchymosis), and raccoon eyes (periorbital ecchymosis). Basilar skull fractures are commonly associated with facial fractures, cervical spine injury, intracranial hemorrhage, cranial nerve injury, vascular injury, and meningitis.[1][2]

Etiology

Most basilar skull fractures are caused by high-velocity blunt trauma such as motor vehicle collisions, motorcycle crashes, and pedestrian injuries. Falls and assaults are also important causes. Penetrating injuries such as gunshot wounds account for less than 10% of cases.[3]

Epidemiology

Basilar skull fractures are relatively uncommon and are present in about 4% of all patients with a severe head injury. They represent 19% to 21% of skull fractures.[4]

Pathophysiology

The location of the fracture is predictive of associated injuries:

  • Temporal fractures, which are most common, are associated with carotid injury, injury to cranial nerves VII or VIII, and mastoid cerebrospinal fluid leak.
  • Anterior skull base fractures are associated with orbital injury, nasal cerebrospinal fluid leak, and injury to cranial nerve I.
  • Central skull base fractures are associated with injury to cranial nerves III, IV, V or VI and carotid injury.
  •  Posterior skull based fractures are associated with a cervical spine injury, vertebral artery injury, and injury to the lower cranial nerves.

History and Physical

Clinical features of basilar skull fractures vary depending on the degree of the associated brain and cranial nerve injury.

Patients may present with altered mental status, nausea, and vomiting.  Oculomotor deficits due to injuries to cranial nerves III, IV, and VI may be present. Patients may also present with facial droop due to compression or injury to cranial nerve VII. Hearing loss or tinnitus suggests damage to cranial nerve VIII.

Several clinical signs highly predictive of basilar skull fracture include:

  • Hemotympanum: Fractures that involve the petrous ridge of the temporal bone will cause blood to pool behind the tympanic membrane causing it to appear purple. This usually appears within hours of injury and may be the earliest clinical finding.
  • CSF rhinorrhea or otorrhea: “Halo” sign is the double ring pattern described when bloody fluid from the ear or nose containing CSF is dripped onto paper or linen. This sign is based on the principle of chromatography; components of a liquid mixture will separate when traveling through a material. This sign is not specific to the presence of CSF, as saline, tears or other liquids will also produce a ring pattern when mixed with blood. CSF leaks may be delayed hours to days after the initial trauma.
  • Periorbital ecchymosis (raccoon eyes): Pooling of blood surrounding the eyes is most commonly associated with fractures of the anterior cranial fossa. This finding is typically not present during the initial evaluation and is delayed by 1 to 3 days. If bilateral, this finding is highly predictive of a basilar skull fracture.
  • Retroauricular or mastoid ecchymosis (Battle’s sign): Pooled blood behind the ears in the mastoid region is associated with fractures to the middle cranial fossa. Like Raccoon eyes, this finding is frequently delayed by 1 to 3 days.

Evaluation

The initial evaluation is usually via non-contrast computed tomography (CT) scan. Unfortunately, skull based fractures that are linear or non-displaced may be difficult to detect. In patients where a high clinical suspicion for basilar skull fracture exists, multidetector CT (MDCT) thin-slice scanning through the face and skull base may aid in the detection of more subtle fractures. Conversely, the detailed small neural and vascular channels visualized on MDCT may be misread as fractures.  Pneumocephalus should raise the suspicion for a basilar skull fracture. Further imaging with CT angiography and venography (CTA, CTV) to assess for vascular injury should be considered in the acute setting. MRI may be useful in assessing nerve injury and in evaluating for cerebrospinal fluid leak.[5][6]

Treatment / Management

Basilar skull fractures are usually due to significant trauma. A thorough trauma evaluation with interventions to stabilize airway, ventilation, and circulatory issues is the priority. Associated cervical spine injury is common, so attention to cervical spine immobilization, particularly during airway management is necessary. Nasogastric tubes and nasotracheal intubation should be avoided because of the risk for inadvertent intracranial tube placement.[3][7][8]

Patients with basilar skull fractures require admission for observation. Those taking anticoagulants should be admitted to a facility with immediate neurosurgical capabilities and the ability to do frequent assessments of the neurologic decline, even if no hemorrhage is present on initial imaging. Patients with intracranial hemorrhage require emergent neurosurgical evaluation. Otherwise, skull base fractures are often managed expectantly. Surgical management is necessary for cases complicated by intracranial bleeding requiring decompression, vascular injury, significant cranial nerve injury, or persistent cerebrospinal fluid leak.

Basilar skull fractures increase the risk of meningitis because of the increased possibility of bacteria from the paranasal sinuses, nasopharynx, and the ear canal making direct contact with the central nervous system.  Patients with associated cerebrospinal fluid leaks, present in up to 45% of patients with basilar skull fractures, are often treated with prophylactic antibiotics to prevent meningitis, but there is no good evidence to support this practice. A recent Cochrane review did not find sufficient evidence to recommend prophylactic antibiotics in patients with basilar skull fractures even in the presence of documented cerebrospinal fluid leak. However, patients with persistent leaks should have cerebrospinal fluid cultures to guide antibiotic therapy, and patients with clinical presentations consistent with meningitis should be treated with empiric antibiotics until culture results are available. While prophylactic antibiotics are not indicated generally, use is still considered appropriate for coverage related to procedures such as insertion of an ICP monitor. Persistent leaks require neurosurgical intervention. Less invasive, endoscopic techniques are becoming common with fewer of these injuries requiring open repair.[9]

Complications

  • CSF leak
  • Meningitis
  • Cranial nerve palsies
  • Hearing loss
  • Cavernous sinus thrombosis
  • Death

Pearls and Other Issues

Complications associated with basilar skull fractures include:

  • Cerebrospinal fluid leak/fistula
  • Meningitis
  • Pneumocephalus
  • Cavernous sinus thrombosis
  • Carotid dissection, pseudoaneurysm or thrombosis
  • Carotid-cavernous fistula
  • Injury to cranial nerves III, IV, VI, VII and VIII

Enhancing Healthcare Team Outcomes

Skull base fractures are not common but when they do occur, they represent a serious life-threatening condition with a very high morbidity and mortality. Because of the diverse presentation, these patients are best managed by a multidisciplinary team that includes a neurosurgeon, neurologist, ophthalmologist, ENT surgeon, a radiologist and an infectious disease specialist. The patients are usually managed in an ICU setting and monitored by a nurse. The outcome of patients with basilar skull fractures depends on whether the fracture is displaced. For nondisplaced fractures, the management is conservative and the outcomes are good. However,, for those with displaced fractures, intervention may be required and this also carries a risk of surgical complications. The key morbidity is meningitis which can be lethal. Those who have a dissection of the carotid artery can develop life-threatening bleeding. Overall, most patients with basilar skull fracture do have some type of residual functional or neurological deficit which may take months or even years to reverse.[10][11]