Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Temporal Bone Trauma


Introduction

Major head injuries can cause a variety of craniofacial fractures. Temporal bone trauma may occur as a result of blunt or nonpenetrating injury or a penetrating injury, such as gunshot wounds. The temporal bone contains several important structures, including the facial nerve, cochleovestibular nerve, labyrinth, ossicles, tympanic membrane, and internal carotid artery, that may be injured as a result of temporal bone trauma. If the force of trauma is strong enough, a fracture of the temporal bone may occur, which can injure these important structures, resulting in various functional deficits, including facial nerve dysfunction, hearing loss, dizziness, and cerebrovascular ischemic injury. Other associated sequelae include intracranial injuries such as hematoma, brain contusion, injury to the abducens nerve, and violation of the dura resulting in cerebrospinal fluid (CSF) leakage with increased risk of bacterial meningitis.

The management of trauma to the temporal bone typically occurs after initiation of trauma resuscitation for acute associated injuries, such as intracranial injury, vascular injury, thoracoabdominal injury, hemorrhage, shock, and other morbid events that require immediate medical or surgical attention. Injuries to the ossicular chain may require surgical management but are typically re-evaluated after several months using techniques described in Chapter 132 (Ossicular Chain Reconstruction). Sensorineural hearing loss and dizziness do not require acute surgical intervention unless there is a significant perilymphatic fistula. Lacerations of the ear canal usually heal spontaneously, but there is a risk of stenosis of the ear canal when severe damage is present in the skin of the ear canal. These cases are typically treated with placement of a wick or stent and steroid/antibiotic ear drops. The few cases that may result in stenosis or atresia of the ear canal can be managed surgically as described in Chapter on Ear Canal Stenosis Repair. The surgical management of CSF leak is described in Chapter 144 (Cerebrospinal Fluid Otorrhea and Encephalocele Repair).

This chapter will discuss in further detail the medical and surgical management of facial nerve injury. The management considerations will be based on a theory of disease based on limited data available at this time.

Key Operative Learning Points

  • 1.

    The bone overlying the facial nerve should be thinned and then gently fractured to remove the loosened bony fragments for atraumatic decompression of the facial nerve.

  • 2.

    The labyrinthine segment of the facial nerve is located at the anterior-superior portion of the fundus of the internal auditory canal, which bisects the angle between the greater superficial petrosal nerve (GSPN) and superior semicircular canal (SSCC).

  • 3.

    Granulation tissue along the facial nerve fracture site should not be dissected aggressively in order to avoid iatrogenic injury to the facial nerve.

Preoperative PERIOD

History

  • 1.

    History of present illness

    • a.

      Penetrating versus nonpenetrating injury

    • b.

      Onset and status of facial nerve dysfunction: This information helps in the stratification of patients’ prognosis for recovery and helps determine who may benefit from surgical intervention.

      • 1)

        Normal after injury with delayed palsy or paralysis

      • 2)

        Immediate onset palsy or paralysis

      • 3)

        Progression of palsy or paralysis over time

    • c.

      Presence of other craniofacial and intracranial injuries

  • 2.

    Past medical history

    • a.

      Prior facial nerve dysfunction such as Bell’s palsy. There may be fewer neurons functioning, even if the facial function returned to normal and lead to poorer prognosis for recovery after the current injury.

    • b.

      Prior ear or mastoid surgeries

    • c.

      Prior intracranial procedures

    • d.

      Diabetes

Physical Examination

  • 1.

    Facial nerve evaluation: House-Brackmann grading scale is typically used

  • 2.

    Otologic evaluation

    • a.

      Tympanic membrane

      • 1)

        Perforation

      • 2)

        Hemotympanum

      • 3)

        CSF otorrhea

    • b.

      Ear canal

      • 1)

        Laceration

      • 2)

        Hemorrhage

    • c.

      Surrounding soft tissue

      • 1)

        Battle’s sign—Postauricular ecchymosis

    • d.

      Tuning fork

    • e.

      Balance evaluation

      • 1)

        Gait

      • 2)

        Tandem gait

      • 3)

        Romberg test

  • 3.

    Rhinologic evaluation

    • a.

      CSF rhinorrhea

  • 4.

    Audiologic evaluation

    • a.

      Pure tones

    • b.

      Speech discrimination scores

    • c.

      Tympanogram

  • 5.

    Electrophysiological studies

    • a.

      Electroneuronography (ENoG)

    • b.

      Electromyography (EMG)

Imaging

Computed tomography (CT) temporal bone—The presence of temporal bone fracture can be confirmed. The locations of probable Fallopian canal fracture sites can also be determined.

Indications for Decompression Surgery

  • 1.

    Patients with a poor prognosis for good facial nerve functional recovery. This includes patients with the clinical findings of immediate onset facial paralysis, immediate onset facial palsy with progression to paralysis, or those with unclear facial function at onset with progression to paralysis, in addition to ENoG showing greater than 95% denervation and EMG showing no voluntary motor potentials.

  • 2.

    Timing—As early as possible, within 12 to 14 days of injury

  • 3.

    Patient has no contraindication to surgery based on medical status and coexisting injuries.

  • 4.

    Some physicians may consider CT findings regarding indication for surgery, but the main indication for surgery remains prognosis for facial nerve recovery based on clinical course and electrical testing.

  • 5.

    Patients who remain unconscious after injury during the 12- to 14-day window for possible facial nerve decompression surgery represent a significant dilemma, as the degree of facial nerve injury cannot be adequately determined. It may be that most of these patients are not good candidates for facial nerve surgery due to the severity of their intracranial injuries. As there are no data correlating the CT findings to the probability of spontaneous facial nerve recovery, it may be prudent not to consider facial nerve surgery in these patients during the acute postinjury period.

Indications for Decompression Surgery

  • 1.

    Evidence of facial nerve transection based on poor facial nerve recovery over 6 to 8 months or high likelihood of facial nerve transection based on clinical presentation

  • 2.

    Timing—Facial nerve repair may be contemplated as early as the traumatic acute inflammatory changes have subsided, typically 4 weeks after injury, if the presence of facial nerve transection has been established.

Contraindications

  • 1.

    Medical comorbidities and/or injuries with increased risk for general anesthesia

Preoperative Preparation

  • 1.

    Ensure that any brain injury has not progressed.

  • 2.

    Confirm status of hearing.

  • 3.

    Obtain and review facial nerve electrical tests to confirm that there is no volitional movement.

Operative Period

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts