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Skull and Spine Disorders

  1. Linear fracture (most common type)
    • deeply black sharply defined line
      DDx:
      1. Vascular groove, esp. temporal artery (gray line, slightly sclerotic margin, branching like a tree, typical location (temporal artery projects behind dorsum sellae)
      2. Suture
  2. Depressed fracture
    • often palpable
    • bone-on-bone density

    Rx: surgery indicated if depression >3–5 mm ← arachnoid tear / brain injury
    N.B.: CT / MR mandatory to assess extent of underlying brain injury
  3. Skull-base fracture = basilar skull fracture
    • rhinorrhea (CSF); otorrhea (CSF / hemotympanum)
    • raccoon eyes = periorbital ecchymosis
    • basic rules for skull fractures:
      • overlying soft-tissue injury / hematoma
      • sharp nonsclerotic border, often crossing sutures
      • may bifurcate
      • increase in diameter as fracture approaches suture
      • diastasis of suture
    • pneumocephalus
    • air in sulci
    • air-fluid level in sinuses
      Cx: infection, acute / delayed cranial nerve deficit, vascular laceration / dissection / occlusion / infarction
      DDx: suture (same diameter, interdigitating “zigzag” pattern)
  4. Healing skull fracture
    • infants: in 3–6 months without a trace
    • children (5–12 years): in 12 months
    • adults: in 2–3 years
    • persistent lucency mimicking vascular groove

    Cx: leptomeningeal cyst (= growing fracture)

Le Fort Fracture!!navigator!!

[René Le Fort (1869–1951), French surgeon]

◊All Le Fort fractures involve the pterygoid process!

  1. Le Fort I = transverse (horizontal) maxillary fracture caused by blow to premaxilla
    Fracture line:
    1. alveolar ridge
    2. lateral aperture of nose
    3. inferior wall of maxillary sinus
    • detachment of alveolar process of maxilla
    • teeth contained in detached fragment
  2. Le Fort II = “pyramidal fracture”
    • May be unilateral


    Fracture line: arch through
    1. posterior alveolar ridge
    2. medial orbital rim
    3. across nasal bones
    • separation of midportion of face
    • floor of orbit + hard palate + nasal cavity involved
  3. Le Fort III = “craniofacial disjunction”
    Fracture line: horizontal course through
    1. nasofrontal suture
    2. maxillofrontal suture
    3. orbital wall
    4. zygomatic arch
    • separation of entire face from base of skull

Sphenoid Bone Fracture!!navigator!!

Prevalence: involved in 15% of skull-base fractures

  • CSF rhinorrhea / otorrhea; hemotympanum
  • “battle” sign = mastoid region ecchymosis
  • raccoon eyes = periorbital ecchymosis; 7th / 8th nerve palsy
  • muscular dysfunction: problems with ocular motility, mastication, speech, swallowing, eustachian tube function
  • air-fluid level in sinuses + mastoid
  • axial thin-slice high-resolution CT for best delineation of fractures
  • water-soluble intrathecal contrast material for CSF fistula

Temporal Bone Fracture!!navigator!!

Frequency: 14–22% of skull fractures

Mechanism: motor vehicle crash (45–47%), fall (31–33%), assault (11–12%)

Cause of conductive hearing loss of temporal bone fracture:

  1. Hemotympanum
  2. Disruption of tympanic membrane
  3. Disruption of the ossicular chain:
    • commonly incus injury:
      1. incudostapedial joint subluxation
      2. malleoincudal subluxation
      3. incus dislocation
      4. dislocation of the malleoincudal complex
    • less commonly: stapedial and mallear fracture

A common complication of temporal bone fractures is hearing loss, either sensorineural, conductive, or mixed.

Longitudinal Fracture of Temporal Bone (75%)

= fracture parallel to long axis of petrous pyramid typically traversing middle ear cavity with frequent disruption of ossicles → conductive hearing loss

Line of force:

  • usually extralabyrinthine from lateral to medial terminating in foramen lacerum; commonly involving EAC (external auditory canal), tegmen tympani, squamosa of temporal bone

Subtypes:

  1. anterior to labyrinthine structures toward eustachian tube + middle cranial fossa (common)
    Cx: epidural hematoma in middle cranial fossa ← vascular injury to middle meningeal artery
  2. posterior to labyrinth, toward jugular foramen and posterior cranial fossa (less common)

Commonly associated with: fracture of temporal squamosa + parietal bone

  • bleeding from EAC ← disruption of tympanic membrane
  • otorrhea ← CSF leak with ruptured tympanic membrane (rare)
  • conductive hearing loss ← dislocation of auditory ossicles (most commonly incus as the least anchored ossicle)
  • NO neurosensory hearing loss
  • facial nerve palsy (7–20%) ← edema / fracture of facial canal near first genu / anterior tympanic segment of facial nerve; frequent spontaneous recovery
  • pneumocephalus
  • herniation of temporal lobe
  • incudostapedial joint dislocation (weakest joint):
    • “ice cream” (malleus) has fallen off the “cone” (incus) on direct coronal CT scan
    • fracture of “molar tooth” on direct sagittal CT scan
  • mastoid air cells opaque / with air-fluid level

Plain film views: Stenvers / Owens projection

Cx: ossicular injury, tympanic membrane rupture, hemotympanum → conductive hearing loss, (rarely) facial n. injury

Transverse Fracture of Temporal Bone (25%)

= fracture perpendicular to long axis of petrous pyramid

Line of force:

  • anterior to posterior originating in occipital bone (near jugular foramen / foramen magnum) extending anteriorly across the base of skull + across the petrous pyramid into middle cranial fossa; commonly passing through / near vestibular aqueduct with variable involvement of otic capsule

Subtypes:

  1. medial relative to arcuate eminence
    Course: traversing fundus of IAC
    • ± complete SNHL ← transection of cochlear n.
  2. lateral relative to arcuate eminence
    Course: traversing bony labyrinth
    Associated with: ± perilymphatic fistula ← injury of stapes footplate
    • ± complete SNHL
  • irreversible sensorineural hearing loss ← fracture line across apex of IAC / labyrinthine capsule with injury to both parts of cranial nerve VIII)
  • persistent vertigo (benign paroxysmal positional vertigo resolves in 6–12 months, perilymphatic fistula, cupulolithiasis = otolith detachment, trauma to semicircular canals)
  • facial (cranial nerve VII) nerve palsy in 50% (injury in IAC); less frequent spontaneous recovery because of disruption of nerve fibers
    Site: labyrinthine segment, geniculate ganglion
  • rhinorrhea ← CSF leak with intact tympanic membrane
  • bleeding into middle ear

Plain film views: posteroanterior (transorbital) + Towne projection

Mixed Temporal Bone Fracture

Temporal bone fractures may be complex with mixed features of both longitudinal + transverse fractures.

= combination of longitudinal + transverse fractures

  • sensorineural hearing loss ← disruption of otic capsule
  • conductive hearing loss ← ossicular injury
  • Quite common!

Ossicular Injury

  • persistent conductive hearing deficit after healing of tympanic membrane / resorption of middle ear debris
  1. Ossicular dislocation: incudostapedial separation >complete separation of incus including incudomalleolar separation >dislocation of malleoincudal complex >stapediovestibular dislocation
  2. Ossicular fracture: long process of incus >crura of stapes >neck of malleus

Zygomaticomaxillary Fracture!!navigator!!

= “TRIPOD” FRACTURE = MALAR / ZYGOMATIC COMPLEX FRACTURE

Cause: direct blow to malar eminence

  • loss of sensibility of face below orbit
  • deficient mastication
  • double vision / ophthalmoplegia
  • facial deformity

Fracture line:

  1. lateral wall of maxillary sinus
  2. orbital rim close to infraorbital foramen
  3. floor of orbit
  4. zygomaticofrontal suture / zygomatic arch

Blowout Fracture!!navigator!!

= isolated fracture of orbital floor

Cause: sudden direct blow to globe (ball or fist) with increase in intraorbital pressure transmitted to weak orbital floor

  • diplopia on upward gaze (entrapment of inferior rectus + inferior oblique muscles)
  • enophthalmos
  • facial anesthesia

Associated with: fracture of the thin lamina papyracea (= medial orbital wall) in 20–50%

  • soft-tissue mass extending into maxillary sinus ← herniation of orbital fat
  • complete opacification of maxillary sinus ← edema + hemorrhage
  • depression of orbital floor (= orbital process of maxilla)
  • posttraumatic atrophy of orbital fat → enophthalmos
  • opacification of adjacent ethmoid air cells
  • disruption of lacrimal duct

Occipital Condyle Fracture!!navigator!!

Anderson & Montesano Types (I–III):

  • I = stable comminution-impaction with minimal / no fracture displacement ← axial loading injury
  • II = linear skull base fracture extending into occipital condyle ← direct blow to head
  • III = unstable avulsion fracture (75%) of occipital condyle ← avulsion injury of alar ligaments ← forced rotation + lateral bending

Tuli Types (1, 2A, 2B)

  • 1 = nondisplaced fracture
  • 2A = displaced fracture WITHOUT ligamentous instability
    Rx: rigid collar
  • 2B = displaced fractures WITH ligamentous instability
    Rx: surgical intervention

Outline