Temporal bone fracture is the most common temporal bone pathology encountered in head trauma, comprising 75-90% of all skull base fractures. Fractures are traditionally classified as longitudinal (70-90%) and transverse (10-20%); however, the current classification of otic capsule-sparing (no bony labyrinth involvement, better prognosis) versus otic capsule-violating (bony labyrinth involvement, high risk of severe sensorineural hearing loss + facial nerve paralysis) is clinically more relevant. Longitudinal fractures extend along the long axis of the temporal bone affecting middle ear structures — causing ossicular dislocation (30-50%), tympanic membrane perforation, and conductive hearing loss. Transverse fractures course along the short axis crossing the otic capsule — resulting in permanent sensorineural hearing loss and facial nerve injury (50%) due to cochlear and vestibular damage. Thin-section temporal bone CT (0.5-0.625 mm) is the gold standard for diagnosis; fracture line, hemotympanum (middle ear opacification), pneumocephalus, ossicular dislocation, and otic capsule involvement are evaluated. MRI additionally assesses facial nerve injury, intracranial complications (epidural hematoma, sigmoid sinus thrombosis), and CSF fistula. Temporal bone fracture should always be evaluated in trauma protocols; particularly in fracture lines extending along the petrous bone, carotid canal and jugular foramen involvement should be investigated.
Age Range
5-80
Peak Age
30
Gender
Equal
Prevalence
Common
Temporal bone fracture results from high-energy head trauma — most common causes are motor vehicle accidents, falls, and assaults. Fracture line orientation depends on impact point and energy vector direction: lateral impact (temporoparietal region) creates longitudinal fracture — energy propagates along the temporal bone long axis passing through squamous, mastoid, and middle ear structures; frontal or occipital impact creates transverse fracture — energy transmits along the short axis crossing the otic capsule. The otic capsule is the densest bone of the bony labyrinth (endochondral ossification) and therefore the most fracture-resistant region — otic capsule-violating fractures require higher energy and carry worse prognosis. Hemotympanum forms when hemorrhage from temporalis muscle, dura, or mucoperiosteum fills the middle ear cavity via the fracture line — appearing as middle ear opacification on CT. Pneumocephalus develops from air entry through tympanic membrane or tegmen tympani fracture. Ossicular dislocation most commonly involves incudostapedial separation (the attachment of the long process of incus to stapes capitulum is weak). Facial nerve injury most commonly occurs at the geniculate ganglion level — this is the narrowest portion of the facial canal and fracture lines frequently traverse the geniculate ganglion. CSF otorrhea results from tegmen tympani or posterior fossa dural tear and poses meningitis risk.
In the current temporal bone fracture classification, classification based on otic capsule involvement is clinically more meaningful than traditional longitudinal/transverse. Otic capsule-sparing fractures bypass the bony labyrinth and typically present with conductive hearing loss (good prognosis). Otic capsule-violating fractures cross the bony labyrinth and are associated with permanent SNHL, facial paralysis, and CSF fistula (poor prognosis). Evaluation of the fracture line relationship to cochlea, vestibule, and semicircular canals on thin-section CT is critical for this classification.
Linear discontinuity in temporal bone structures on thin-section temporal bone CT (0.5-0.625 mm, bone algorithm) — fracture line course, length, and orientation are evaluated. Axial and coronal reformatted images are used together. Longitudinal fractures start from squamous bone, course along tegmen tympani, cross middle ear structures, and may extend to carotid canal. Transverse fractures start from foramen magnum, course along the short axis of petrous bone, and cross the otic capsule. Mixed fractures contain both components (30-50%). Accompanying cranial fracture is found in 80% of temporal bone fractures.
Report Sentence
__ type (longitudinal/transverse/mixed) fracture line observed in the temporal bone extending through __ structures; otic capsule involvement __ (present/absent).
Soft tissue density opacification in the middle ear cavity — represents hemotympanum (blood accumulation) in the context of acute trauma. Opacification may be homogeneous or heterogeneous. Ossicular chain continues to be visible within the opacification (not completely obscured). Air-fluid level may be seen. Blood may also extend to mastoid cells. Hemotympanum is the most common associated finding of temporal bone fracture (60-80%) and should always prompt search for fracture line.
Report Sentence
Soft tissue density opacification in the middle ear cavity, consistent with hemotympanum in the context of trauma.
Free air in the intracranial compartment (epidural, subdural, or subarachnoid space) — indicates passage of external or middle ear air into the intracranial space through tympanic membrane or tegmen tympani tear caused by temporal bone fracture. Air appears as very low density (-1000 HU) black focus on CT. Pneumocephalus may be small (few air bubbles) or massive (tension pneumocephalus — mass effect). Accompanies 20-30% of temporal bone fractures.
Report Sentence
Intracranial free air (pneumocephalus) at __ location, consistent with dural defect secondary to temporal bone fracture.
Disruption of normal anatomic relationships of the ossicular chain — most common is incudostapedial separation (80% of ossicular injuries), second is incudomalleolar separation. Loss of relationship between incus long process and stapes capitulum on axial CT (loss of normal 'ice cream cone' appearance) is the diagnostic clue. Incus is the most commonly dislocated ossicle as its long process is the most fragile structure. Stapes fracture is rare but may cause perilymphatic fistula with vestibule window damage. Bone algorithm CT at 0.5 mm slice thickness is mandatory for ossicular pathology.
Report Sentence
Ossicular chain dislocation at __ level, consistent with traumatic ossicular injury secondary to temporal bone fracture.
Increased T2 signal and thickening of the facial nerve at segments where the fracture line crosses the facial nerve course — indicates edema, contusion, or transection. Geniculate ganglion is the most commonly affected segment (narrowest point of the facial canal). Contrast-enhanced MRI may show abnormal enhancement of the facial nerve. Tympanic and mastoid segments may also be involved. Facial nerve function is clinically assessed using House-Brackmann scale. MRI is superior to CT for determining the level and degree of facial nerve injury.
Report Sentence
T2 signal increase and thickening of the facial nerve at __ segment, consistent with traumatic nerve injury; clinical correlation and House-Brackmann grading recommended.
Fracture line crossing the bony labyrinth (cochlea, vestibule, semicircular canals) — defined as otic capsule-violating fracture and unlike the sparing type carries risk of severe sensorineural hearing loss (100%), facial nerve paralysis (50%), and CSF fistula (40%). The otic capsule is the densest bone structure formed by endochondral ossification and requires high energy for fracture. Axial and coronal CT directly visualize the fracture line crossing cochlear turns, vestibular cavity, or semicircular canal lumens.
Report Sentence
Fracture line crosses the otic capsule (otic capsule-violating fracture) carrying risk of severe sensorineural hearing loss and facial nerve paralysis; emergent otological evaluation recommended.
Criteria
Fracture coursing along the long axis of temporal bone, starting from squamous bone, passing through tegmen tympani and middle ear. Comprises 70-90% of all temporal bone fractures.
Distinct Features
Conductive hearing loss, tympanic membrane perforation, hemotympanum, facial paralysis 10-25%, CSF otorrhea rare. Caused by lateral impact (temporoparietal).
Criteria
Fracture coursing along the short axis of temporal bone, starting from foramen magnum crossing the otic capsule. Comprises 10-20% of all temporal bone fractures.
Distinct Features
Sensorineural hearing loss (permanent), facial paralysis 50%, CSF otorrhea/rhinorrhea common, vertigo. Caused by frontal/occipital impact. Requires higher energy.
Criteria
Fracture containing both longitudinal and transverse components. In real practice, 30-50% of fractures are mixed type.
Distinct Features
Mixed clinical picture — elements of both conductive and sensorineural loss. Prognosis depends on dominant fracture component. Poor prognosis if otic capsule involvement present.
Criteria
Fracture line crossing the bony labyrinth (cochlea, vestibule, semicircular canals). Most critical distinction point in current classification.
Distinct Features
SNHL 100% permanent, facial paralysis 50%, CSF fistula 40%. High-energy trauma. Only 2-6% of all temporal bone fractures.
Distinguishing Feature
Coalescent mastoiditis shows inflammatory bone erosion (mastoid septal erosion) but no fracture line and no trauma history. Clinical picture is dominated by fever and infection signs.
Distinguishing Feature
Middle ear effusion has opacification but no fracture line, pneumocephalus, or ossicular dislocation. Bone structures are intact. No trauma history and clinical course is more chronic.
Distinguishing Feature
Large vestibular aqueduct is a congenital anomaly — bone discontinuity does not resemble fracture line, shows smooth-bordered enlargement. No trauma history. Presents with bilateral hearing loss in pediatric patient.
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralTemporal bone fracture is a trauma pathology requiring emergent evaluation. Priority assessment order: (1) facial nerve function — acute-onset complete paralysis is an indication for surgical exploration; (2) CSF fistula — monitoring or surgical repair due to meningitis risk; (3) hearing loss — ossiculoplasty can be planned for conductive type, SNHL is permanent; (4) vascular injury — carotid canal fracture carries risk of internal carotid artery dissection/pseudoaneurysm (CT angiography). Hemotympanum usually self-resorbs (2-4 weeks). Pneumocephalus is conservatively monitored in most cases; tension pneumocephalus requires emergent decompression.
Temporal bone fractures can lead to serious complications: facial nerve paralysis (especially transverse type), CSF fistula (otorrhea/rhinorrhea), meningitis risk, hearing loss (conductive or sensorineural). Otic capsule-violating fractures have worse prognosis. Requires emergent neurological and otological evaluation.