Residency · Residency · Otolaryngology
Temporal Bone Fractures
Introduction
Temporal bone fractures occur in approximately 14-22% of all skull fractures and result from significant blunt head trauma. The temporal bone houses critical structures including the hearing apparatus, vestibular system, facial nerve, and carotid artery. Classification has evolved from the traditional longitudinal/transverse system to a more clinically relevant system based on otic capsule involvement.
Anatomy Review
Petrous portion: dense bone housing the cochlea, vestibule, and semicircular canals (otic capsule). Squamous portion: thin lateral wall. Tympanic portion: forms the anterior, inferior, and posterior walls of the external auditory canal. Mastoid portion: air-cell system posterior to the middle ear. Facial nerve: intratemporal course through the IAC, labyrinthine segment, geniculate ganglion, tympanic segment, and mastoid segment. Carotid canal: transmits the internal carotid artery through the petrous apex.
Classification
Traditional (Longitudinal vs. Transverse)
Longitudinal (70-80%): fracture line parallel to the long axis of the petrous bone; involves the EAC, middle ear, and tegmen; typically spares the otic capsule. Transverse (10-20%): fracture line perpendicular to the petrous axis; crosses the otic capsule; higher rates of SNHL and facial nerve injury. Mixed/oblique: most common pattern in reality; does not fit neatly into either category.
Modern Classification (Otic Capsule Involvement)
| Feature | Otic Capsule Sparing (OCS) | Otic Capsule Violating (OCV) |
|---|---|---|
| Frequency | ~95% | ~5% |
| Hearing loss | Conductive (hemotympanum, ossicular disruption) | Severe SNHL |
| Facial nerve injury | Lower risk | 7x higher risk |
| CSF leak | Lower risk | 4x higher risk |
| Vertigo | Less common | Common (labyrinthine damage) |
Otic capsule sparing (OCS): ~95% of cases; fracture line does not involve the cochlea or vestibule; typically causes CHL. Otic capsule violating (OCV): ~5% of cases; crosses the cochlea, vestibule, or semicircular canals; causes severe SNHL; 7x higher rate of facial nerve injury, 4x higher rate of CSF leak.
Clinical Presentation
Signs and Symptoms
Hearing loss: conductive (ossicular disruption, hemotympanum, TM perforation) or sensorineural (otic capsule violation, cochlear concussion). Hemotympanum: blood behind the TM (most common finding). EAC laceration and bleeding. Battle sign: mastoid ecchymosis (delayed 24-48 hours). CSF otorrhea: clear fluid from the ear, or CSF rhinorrhea if TM is intact (drains through Eustachian tube). Facial nerve paralysis: immediate or delayed onset. Vertigo and nystagmus: from labyrinthine injury or perilymph fistula. Conductive hearing loss: from ossicular chain disruption (incudostapedial joint separation is most common).
Evaluation
Clinical Assessment
Complete neurologic examination including GCS and cranial nerves. Otoscopy: hemotympanum, EAC step-off, TM perforation, CSF otorrhea. Facial nerve assessment: House-Brackmann grading; distinguish immediate from delayed onset. Tuning fork tests: Weber and Rinne to differentiate CHL from SNHL.
Audiologic Testing
Audiometry when patient is stable: characterize type and degree of hearing loss. ABR: if patient cannot cooperate with behavioral audiometry.
Imaging
High-resolution CT temporal bone (0.5-0.625 mm cuts): axial and coronal reformats. Evaluate: fracture course, otic capsule involvement, ossicular displacement, facial nerve canal involvement, pneumocephalus. CT angiography: if fracture involves the carotid canal (risk of carotid dissection, pseudoaneurysm). MRI: for suspected facial nerve injury (enhancement), CSF leak localization, or intracranial complications.
Management
Hearing Loss
Conductive hearing loss with hemotympanum: observe; typically resolves as blood resorbs (6-8 weeks). Persistent CHL >3 months: suggests ossicular discontinuity; CT evaluation and possible ossiculoplasty. SNHL from otic capsule violation: typically permanent; hearing rehabilitation (hearing aids, cochlear implant if bilateral severe/profound). Cochlear concussion: may partially recover; steroids are often given empirically.
Facial Nerve Injury
Delayed onset paralysis (most common): excellent prognosis (>90% recover to HB I-II); managed conservatively with steroids and observation. Immediate complete paralysis: suggests nerve transection or compression; may benefit from surgical exploration and decompression. Electroneuronography (ENoG): performed days 3-14; >90% degeneration suggests poor prognosis without intervention. Surgical decompression: transmastoid approach for tympanic and mastoid segments; middle fossa approach for labyrinthine segment and geniculate ganglion. Timing: surgery within 2-3 weeks of injury if indicated.
CSF Leak
Conservative management: head-of-bed elevation, avoidance of straining, stool softeners. 80-95% resolve spontaneously within 7-10 days. Lumbar drain: for persistent leaks. Surgical repair: for leaks persisting beyond 7-14 days; risk of meningitis increases with duration. Antibiotics: prophylactic use is controversial and not routinely recommended.
Carotid Injury
Fractures involving the carotid canal warrant CTA screening. Carotid dissection or pseudoaneurysm: anticoagulation or antiplatelet therapy; endovascular stenting if symptomatic.
Complications
Meningitis: risk highest with persistent CSF leak; reported in 4-17% of OCV fractures. Cholesteatoma: trapped skin from EAC laceration or TM perforation (post-traumatic cholesteatoma). Delayed facial paralysis: typically onset days 3-14; nearly always recovers. Perilymph fistula: from otic capsule disruption; vertigo and fluctuating SNHL. Carotid-cavernous fistula: rare but serious vascular complication.
Key Clinical Pearls
The otic capsule classification is more clinically useful than the traditional longitudinal/transverse system. Immediate complete facial paralysis has a worse prognosis than delayed onset and may require surgical exploration. CSF otorrhea resolves conservatively in the vast majority of cases; reserve surgery for persistent leaks. Always obtain CTA when fracture lines involve the carotid canal. Post-traumatic conductive hearing loss persisting beyond 3 months warrants evaluation for ossicular disruption. Incudostapedial joint dislocation is the most common ossicular injury in temporal bone fractures.
References
- Dahiya R, Keller JD, Litofsky NS, et al. Temporal bone fractures: otic capsule sparing versus otic capsule violating clinical and radiographic considerations. J Trauma. 1999;47(6):1079-1083.
- Brodie HA, Thompson TC. Management of complications from 820 temporal bone fractures. Am J Otol. 1997;18(2):188-197.
- Nash JJ, Friedland DR, Boorsma KJ, Rhee JS. Management and outcomes of facial paralysis from intratemporal blunt trauma: a systematic review. Laryngoscope. 2010;120(Suppl 4):S214.
- Rafferty MA, Mc Conn Walsh R, Walsh MA. A comparison of temporal bone fracture classification systems. Clin Otolaryngol. 2006;31(4):287-291.
For the intern
At 3am, your trauma patient with a temporal bone fracture needs immediate assessment of facial nerve function (document House-Brackmann grade and whether onset was immediate or delayed), CSF otorrhea (look for clear fluid, check beta-2 transferrin if unclear), and signs of carotid injury (examine CT for carotid canal involvement—order CTA if present). Elevate the head of bed, start eye care if facial paralysis exists, and hold antibiotics unless there's active meningitis. Everything else—audiometry, surgical consultations for ossicular injury, ENoG testing—waits until morning rounds when the attending can review imaging and plan definitive management.
Common pitfalls
- Giving prophylactic antibiotics for CSF leak: Not routinely recommended and creates false reassurance while promoting resistance. Most leaks (80-95%) resolve with conservative measures alone.
- Panicking about delayed facial paralysis: This has excellent prognosis (>90% recovery) with observation and steroids. Immediate complete paralysis is the concerning presentation requiring urgent workup.
- Missing carotid canal involvement: Fracture lines through the carotid canal require CT angiography screening—dissection and pseudoaneurysm can be catastrophic if undetected.
- Ordering audiometry too early: Hemotympanum causes temporary conductive loss. Wait 6-8 weeks before assuming ossicular disruption; only persistent hearing loss beyond 3 months warrants surgical exploration.