Neuro-temporal bone, orbit & skull base/neck Flashcards
Longitudinal vs transverse temporal bones fractures
- Long: long axis, MC, more ossicular dislocation, conductive hearing loss
- TV: short axis, van injury, sensorineuronal
MC facial fracture
nasal bone
MC facial fracture pattern
zygomaticomaxillary complex fracture (tripod)-zymgoma, inf orbit, lateral orbit
Le-Fort Fractures
involve pterygoid process
1) floating palate-anterolateral margin of nasal loss
2) pyramidal-inferior orbital rim & floor
3) separated face- zygomatic arch, lateral orbital rim wall
MC fracture site to result in CSF leak
anterior skull base
“recurrent bacterial meningitis”
known association with CSF leak
What is the best predictive factor ISO temporal bone fx?
otic capsule violation
Division of middle ear cavity
- epitympanum
- hypotympanum
- mesotympanum
hypotympanum-where, what arises from it?
- Below tympanic membrane.
- Eustachian tube arises from here.
epitympanum
- “attic”
- above tip of scutum
mesotympanum
-directly behind tympanic membrane
Two parts of tympanic membrane
1) pars flaccida (top, weaker)
2) pars tensa (bottom)
cholesteatoma-what, specific sgx, MRI img
blob of exfoliated skin in middle ear cavity secondary to hole in pars flaccid.
- erosion of scutum (v. specific sgx)
- RD+
Two types cholesteatoma
1) pars flaccida
2) pars tensa
Pars flaccida type cholesteatoma
- MC
- Prussak’s space= MC loc
- Early erosion scutum
- long process incus MC segment of ossicular chain to be eroded
- fistula to SCC MC involve lateral segment
pars tensa type cholesteatoma
- less common
- inner ear involvement occ MC & earlier
prussau’s space
btw incus body (medial) and temporal bone process/scutum (lateral)
otic capsule aka
- bony labyrinthine
- SCC, vestibule, cochlea
- normally fluid filled
labyrinthine fistula (perilymphatic fistula)
- 2/2 cholesteatoma, iatrogenic, trauma
- abN conn with MEC (air-filled)
- Lat SCC MC involved
- “sudden fluctuating sensorineural hearing loss & vertigo)
imaging labyrinthine fistula 2/2 cholesteatoma
- ST density eating through otic capsule into SCC
- pneumolabyrinth-not often seen
“chronic” OM
fluid in MEC >6wks
In whom is OM common?
kids & DS (horn Eustachian tube)
complications of OM
1) coalescent mastoiditis-erosion mastoid septa w/ or w/o intramastoid abscess
2) facial n palsy-2/2 inflammation tympanic segment
3) dural sinus thrombosis–> venous infarct, otitic hydrocephalus
4) meningitis, labyrinthitis
labyrinthitis ossificants
“hx of childhood meningitis”
- kids, 2-18 mo’s
- img: ossification of membranous labyrinth
- sensorineural hearing loss
- calcification of cochlea CI for cochlear implant