# 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.

![Axial CT of the temporal bone demonstrating an otic capsule-sparing fracture with hemotympanum and EAC involvement](/images/temporal-bone-fracture-ct.jpg)

## 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.

![Coronal CT showing an otic capsule-violating temporal bone fracture traversing the cochlea](/images/otic-capsule-violating-fracture.jpg)

## 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.

![MRI of the temporal bone showing facial nerve enhancement at the geniculate ganglion in a patient with delayed facial paralysis](/images/facial-nerve-enhancement-mri.jpg)

## 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

1. 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.
2. Brodie HA, Thompson TC. Management of complications from 820 temporal bone fractures. *Am J Otol*. 1997;18(2):188-197.
3. 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.
4. Rafferty MA, Mc Conn Walsh R, Walsh MA. A comparison of temporal bone fracture classification systems. *Clin Otolaryngol*. 2006;31(4):287-291.