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Temporal Bone Trauma 

Overview
The temporal bone houses several important structures including the otic capsule containing the cochlea and vestibular labyrinth, facial nerve, ossicles, and carotid canal. Furthermore, its superior and medial boundaries comprise the dura of the middle fossa and posterior fossa, respectively. Thus, temporal bone fractures may result in temporary or permanent facial nerve injury, hearing loss (conductive, sensorineural or mixed), vertigo, CSF leak or meningitis. Fractures of the temporal bone typically require significant force and therefore frequently occur in association with other significant maxillofacial, skull base or cranial injuries. Diagnosis is made most often following emergent head or maxillofacial CT scan in the trauma bay. Typically, head CTs have thick cuts which may not capture small structures in the temporal bone and additional imaging may be required. 

Evaluation and management of temporal bone trauma typically ensues following general trauma stabilization. Patient evaluation should assess for injuries involving the critical structures within the temporal bone. The most important information to document upon patient arrival to the hospital is facial nerve function. If a patient has facial nerve paralysis at the time of evaluation, it would be important to attempt to determine if this occurred immediately after the injury or in a delayed fashion. This may be challenging to elicit, since many patients are polytraumas and facial nerve function is often not prioritized during an initial in-field assessment. Symptomatically, patients will most commonly experience conductive hearing loss secondary to hemotympanum, tympanic membrane tear or external auditory canal occlusion from soft-tissue injury. However, temporal bone fractures can violate the otic capsule and thereby cause sensorineural hearing loss. Although patients with major traumatic injuries may be intubated and sedated thereby precluding a good facial nerve and audiological assessment, a 512-hertz tuning fork examination in an awake patient can be helpful. Concomitant vertigo and associated nystagmus should also raise concern for otic capsule involvement. 

As the consulting otolaryngologist, a careful radiologic review of available temporal bone imaging should be performed. It is often helpful to review the scans with the neuroradiology team if any questions arise. A systematic review of structures should include evaluation of the otic capsule, internal auditory canal, facial nerve path, ossicles, external auditory canal, middle and posterior fossa bony plates, temporomandibular joint, and vascular structures (carotid and sigmoid). Prognostically, otic capsule-involving fractures are more likely to have facial nerve injury, CSF leak, and sensorineural hearing loss. Identification of fluid signal in the mastoid, air in the labyrinth (i.e., pneumolabyrinth) and intracranial air (i.e., pneumocephalus) – fluid where air should be and air where fluid should be – offer immediate and reliable clues to injury of the respective regions. The astute resident should also use the contralateral ear as a “control” to ensure that normal sutures and other structures (e.g., singular canal, cochlear aqueduct) are not misinterpreted as fracture lines.

Classification Schema
Historically, temporal bone fractures were classified based on their relationship with the long axis of the petrous ridge. Under this classification, longitudinal fractures occurred in parallel to the petrous ridge whereas transverse fractures occurred in perpendicular orientation to the petrous ridge, most commonly traversing the foramen magnum. Transverse fractures are considered less common than longitudinal fractures but portend increased risk of facial nerve injury and otic capsule involvement. Fractures are now commonly classified as otic capsule sparing or violating.

Key Supplies for Consultation

  • Appropriate PPE including mask, eye protection, gloves, and gown

  • Otoscope

  • 512-Hertz tuning fork

  • Cerumen currette

  • Suction trap if fluid collection for CSF analysis is anticipated

  • Ear wick

  • If cleaning debris from the ear canal, will need operating microscope, size 3, 4 or 5 ear speculum, size 5 or size 7 straight suction, suction source

Complications and Management 

Facial Nerve Injury 

  • Documentation of the timing and severity of facial nerve weakness is key. The House-Brackmann facial nerve scale is a convenient way to record facial nerve function

  • Facial nerve paresis (partial weakness) or delayed facial nerve paralysis carry a more favorable prognosis compared to immediate onset complete facial nerve paralysis

  • Facial nerve paralysis or paresis, regardless of timing, is typically treated with high-dose corticosteroids (such as oral prednisone) if not medically contraindicated

  • In the setting of significant facial weakness (House-Brackmann IV or worse), careful attention must be paid to the patient’s eye closure

  • Patients with lagophthalmos should be given artificial tears, lubricating eye ointment, and precautions to avoid inadvertent corneal injury (e.g., moisture chamber at night while sleeping)

  • In the setting of early complete, House-Brackmann VI facial nerve paralysis, surgical exploration with decompression may be considered. Although controversial, electroneuronography (EnOG) should be considered between 3-14 days after time of injury if one is contemplating facial nerve decompression

  • Waiting 3 days allows for Wallerian degeneration to take place 

  • Degeneration of >90% on EnOG and confirmation with EMG may warrant facial nerve decompression

  • Close follow up to monitor facial nerve function and related complications 

Hearing Loss

  • External auditory canal skin laceration is very common. Bedside debridement is recommended to allow for treatment with ototopical antibiotics. In some cases, circumferential lacerations may benefit from stenting with otowick placement

  • In the acute setting, conductive hearing loss secondary to hemotympanum, tympanic membrane tear, or ossicular chain disruption is typically treated conservatively with observation

  • Sensorineural hearing loss stemming from an otic capsule-involving fracture can be treated with high-dose corticosteroids, although outcomes are variable. Patients with otic capsule involvement will also commonly have associated vertigo and nystagmus on examination

  • Early after the injury, a 512-hertz tuning fork examination is important to perform. A Weber test (tuning fork placed firmly on midline, such as the forehead) will lateralize to the size with better sensorineural function or the side with the greater conductive hearing loss. The Rinne test is used to distinguish sensorineural from conductive hearing loss for each individual ear. In a normal healthy ear, air conduction (tuning fork held 2-4 cm from the external auditory canal) should be greater than bone conduction (tuning fork firmly pressed on mastoid process). A person with temporal bone trauma and isolated conductive hearing loss will usually have a Weber that lateralizes to the affected ear, and on Rinne testing bone conduction will be greater than air.  A crude bedside test using the phone dial tone can also be considered. An early audiogram with bone conduction thresholds should be obtained if sensorineural hearing loss is suspected

  • If only conductive hearing loss is suspected and imaging does not reveal otic capsule involvement, a formal audiogram is obtained about 8-12 weeks after injury to allow for resolution of middle ear fluid and inflammation. Surgical treatment may be indicated in persistent conductive hearing loss

CSF Leak

  • While CSF leaks are relatively uncommon, patients should be evaluated for CSF otorrhea or rhinorrhea, especially in cases of otic capsule or skull base violation. Draining fluid suspected to be CSF can be tested for Beta 2-transferrin, which is highly sensitive and specific for CSF. Notably, a halo or ring sign is not sensitive or specific for a CSF leak

  • Since most traumatic CSF leaks self-resolve, initial management is conservative and aims to reduce intracranial pressures with head of bed elevation to 30 degrees, limited activity, stool softeners and avoidance of straining

  • Use of prophylactic antibiotics is controversial though commonly administered

  • Lumbar drains are typically avoided in the early setting

  • Persistent CSF leak beyond 1-2 weeks may require surgical repair

 Others

  • Persistent vertigo is uncommon, but may be associated with posttraumatic BPPV, otic capsule fracture or perilymphatic fistula

  • Fractures involving the carotid canal should be evaluated with CTA to rule out internal carotid dissection

References

  1. Wilkerson, B.J., et al (2020). Management of Temporal Bone Trauma. In P.W. Flint, et al (Eds.), Cummings Otolaryngology Head and Neck Surgery 7e (pp. 2207-2219). Philadelphia, PA: Elsevier.

  2. Diaz, R.C., et al. (2013). Middle Ear and Temporal Bone Trauma. In J.J. Johnson, C.A. Rosen. (Eds.), Bailey’s Head and Neck Surgery-Otolaryngology 5e (pp. 2410-2432). Baltimore, MD: Lippincott Williams & Wilkins. 

  3. Fusetti, S. et al. “Treatment of Temporal Bone (Lateral Skull Base).” AO Foundation Surgery Reference, https://surgeryreference.aofoundation.org/cmf/trauma/skull-base-cranial-vault/temporal-bone-lateral-skull-base