Temporal Bone Fractures

Incidence

Temporal bone fractures occur in 1%–9% of all head injuries, in 5% of all skull fractures, but in 36% of skull base fractures. Fractures are more common in males with an average age of 32–41 years in adults and 4–7 years in children.

History and Physical Examination

A complete head and neck exam is performed to confirm airway stability, neurological status, soft tissue injury, craniofacial fractures, and cranial nerve status. Life-threatening injuries are addressed first. Mortality in these individuals is 10%. Almost half report loss of consciousness (LOC) and in children, LOC, altered mental status (AMS), headache, and nausea/vomiting are common findings. Intracranial injuries are seen in up to 79% of temporal bone fractures. Common injuries include subdural hematoma and subarachnoid hemorrhage, with 17%–30% of patients requiring surgical neurological intervention.

Hemotympanum, hearing loss, vertigo, and nystagmus are strong predictors of temporal bone fractures. Other suggestive findings include external auditory canal (EAC) lacerations, otorrhagia, and tympanic membrane (TM) perforation. Classically, the examiner may appreciate ecchymosis over the mastoid tip (“Battle's sign”), hemotympanum or periorbital ecchymosis (“raccoon eyes”).

Otorrhagia is common, and the presence of a “halo sign” (clear fluid ring external to internal blood ring when ear fluid drains onto filter paper) can signal a leak of cerebrospinal fluid (CSF). Significant bleeding can indicate a carotid injury. Prompt packing, imaging, and consultation with vascular surgery, interventional neuroradiology, or neurosurgery are necessary.

Presence of nystagmus can suggest OC trauma. The direction of the nystagmus can provide a clue as to which labyrinth may be affected with nystagmus beating towards the intact ear. Once the patient's C-spine is cleared, head impulse testing to assess semicircular canal function and Dix–Hallpike testing for benign paroxysmal positioning vertigo (BPPV) are performed. Presence of direction changing, pendular, or vertical nystagmus that does not suppress with visual input may suggest central findings and should be further investigated.

As soon as the patient is cooperative, a facial nerve exam should be consistently documented. It is critical that each of the five branches of the facial nerve is examined. Temporal bone fractures generally affect all five branches of the facial nerve, and examination should note the degree of brow elevation, eye closure (minimal and maximal effort), nasal ala flaring/nasolabial fold symmetry, and oral commissure symmetry with efforts at smiling, lip pursing, and frowning.

Hearing Test

Hearing loss is the most common complaint, with up to 80% of patients experiencing it. A 512 Hz tuning fork exam can distinguish a conductive hearing loss (CHL) from a sensorineural hearing loss (SNHL). An audiogram should be obtained 4–6 weeks following injury.

Radiological Evaluation

Computed tomography (CT) is the best modality for assessing temporal bone fractures ( Fig. 1.17.2 ). Opacification of air cells and pneumocephalus can suggest a fracture. Pneumolabyrinth suggests OC involvement and is found in up to 8% of fractures. A head, maxillofacial, or cervical CT can detect a fracture without the need for a dedicated temporal bone scan. The sensitivity and specificity of a maxillofacial CT scan in cases of blunt head trauma and associated vascular injury are greater than 90% and imply a negative predictive value of >95%. A separate HRCT can add cost, radiation exposure, and time to a work-up without significantly changing management. However, if standard imaging does not show a fracture but physical exam suggests its presence, or if management dictates the superior anatomical information offered by HRCT, then a dedicated temporal bone CT should be obtained. In cases where surgical management is considered or an unreliable clinical exam is present, a HRCT scan provides adjuvant information that changes treatment.

HRCT should include proper filters for bone edge detection and reconstructions from small fields of view with minimal slice thickness (e.g. 0.5 mm) and spacing (ideally 0 mm). Scans obtained with spiral technique or from multidetector scanners using 0.5 mm ³ or smaller voxels allow for reconstructions in any plane without loss of resolution. For pediatric patients, low-dose radiation protocols may be used; however, evaluation of small structures may be difficult. The evolution of flat panel CT is a promising development that may offer even higher resolution of bony anatomic detail with lower total radiation dose. No matter the technique used for HRCT, the clinician should review the images and correlate physical findings with imaging ( Box 1.17.1 ).

Fractures involving vascular structures should be examined with CT angiography as the stroke rate for carotid artery injury is 31%–33% in this population. Findings include vessel wall irregularity, changes in vessel caliber, abnormal outpouching, and occlusion of a vessel or a contrast blush indicating extravasation of blood. The gold standard is catheter angiography. In a retrospective review, 38% of patients with temporal bone fractures who underwent angiography had abnormal findings, including pseudoaneurysm, carotid dissection, and vasospasm.