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CORE: Neuro > Temporal Bone > Flashcards

Temporal Bone Flashcards

1
Q

pathology of external ear

A

EAC atresia, SCC, swimmer’s ear (acute external otitis), surfer’s ear (EAC exostosis), malignant otitis externa, acute external otitis, first branchial cleft cyst, keratosis obturans

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2
Q

pathology of middle ear

A

hypoplasia of ossicles, cholesteatoma, otitis media, mastoiditis, glomus tympanicum, aberrant ICA, dehiscent jugular bulb, oval window atresia, facial nerve schwannoma

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3
Q

pathology of inner ear

A

cochlear dysplasia, superior semicircular canal dehiscense, semicircular canal hypoplasia, enlarged vestibular aqueduct, otospongiosis/otosclerosis, Paget disease, fibrous dysplasia, labryrinthitis, petrous apicitis, cholesterol cyst

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4
Q

middle ear contents

A

tympanic membrane
ossicles (malleius/incus/stapes)
stapedius muscle
facial nerve

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5
Q

inner ear contents

A

cochlea, semicircular canals, vestibule, utricle, saccule, vestibular aqueduct, coclear aqueduct

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6
Q

congenital EAC stenosis, hypoplasia, atresia

A

malformations of external ear

typically inner ear not involved since it has different embryological origin

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7
Q

acute external otitis media

A

swimmers ear; bacterial infection of external ear since in high humidity

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8
Q

EAC exostosis

A

surfer’s ear; exostosis of EAC in those who swim/surf in cold waters

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9
Q

necrotizing external otitis

A

malignant otitis externa; seen in elderly diabetic/immunocompromised; Pseudomonas vs Aspergillus

extensive enhancement around external ear with associated bony erosion

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10
Q

Keratosis obturans

A

keratin plugs within an enlarged EAC; seen in young patients with sinusitis and bronchiectasis

usually bilateral

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11
Q

cholesteatoma

A

acquired cholestatoma, more common in middle ear

usually associated with bony erosion

white mass behind tympanic membrane; restricts diffusion

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12
Q

EAC malignancy

A

SCC–usually sun exposure or chronic inflammation

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13
Q

oval window separates?

A

air filled middle ear and fluid filled inner ear

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14
Q

glomus tympanicum

A

extra adrenal pheochromocytoma (paraganglioma) of the middle ear

associated with pulsatile tinnitus or conductive eharing loss

vascular red mass behind the tympanic membrane

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15
Q

facial nerve schwannoma

A

present with facial nerve palsy;

involve geniculate ganglion, followed by labryinthine and tympanic segments

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16
Q

facial nerve segments

A

labryinthine, tympanic, mastoid

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17
Q

labrinthine segment, tympanic membrane

A

IAC to geniculate ganglion; superior to cochlea

gives off greater suprficial petrosal nerve

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18
Q

tympanic segment tympanic membrane

A

horizontal; courses under lateral semicircular canal

19
Q

mastoid segment tympanic membrane

A

descending; courses inferiorly then exits at the stylomastoid foramen

nerve to stapedius
chorda tympani

20
Q

cholesterol granuloma

A

cholesterol cyst; petrous apex lesion that may occur in the middle ear

giant cell reaction to cholesterol crystals initially incited by an obstructed air cell

blue mass behind tympanic membrane

21
Q

cholesteatoma, middle ear

A

non-neoplastic lesion of temporal bone; skin in the wrong place; white mass behind tympanic membrane

persistent fetal epithelial squamous cell nests, or due to sequela of tympanic membrane perforation, inflammation, trauma

more common in younger individuals (EAC cholesteatomas in older/middle aged)

22
Q

cochlear dysplasia

A

mondini deformity
incomplete development of cochlea resulting in confluence of apical/middle turns; intact basilar turn

incomplete partition type II

23
Q

michel aplasia

A

complete lack of development of inner ear

24
Q

enlarged vestibular aqueduct syndrome

A

may lead to progressive hearing loss while playing contact sports

vestibular aqueduct should not be larger than posterior semicircular canal; often seen at same level in axial plane

25
Q

otospongiosis

A

otosclerosis; bone dysplasia of otic capsule seen in young/middle aged women; bilateral usually

types fenestral and retrofenestral

26
Q

retrofenestral and fenestral otospongiosis

A

fenestral: more common; fissula ante fenestrum (anterior to oval window)

retrofenestral (cochlear): severe form; involve otic capsule and lateral wall of labryinth

27
Q

ddx of cochlear demineralization

A

retrofenestral otospongiosis, osteogenesis imperfecta, fibrous dysplasia, paget disease (based on age)

28
Q

labryinthitis

A

inflammation of inner ear: infectious/autoimmune

3 stages: acute > fibrous > labrytinthitis ossificans

29
Q

acute labyrinthitis

A

pus in inner ear; enhancement of inner ear

may also look like cochlear/intralabyrinthine schwannoma

30
Q

fibrous labyrinthitis

A

endolymph/perilymph replaced with fibrous strands

mild/decreased post-contrast enhancement

31
Q

labryinthitis ossificans

A

final stage of labyrinthitis

calcified debri where normal endolymph and perilymph is seen

best evaluated on CT for calcifications; decreased signal on T2 weighted MRI

32
Q

types of temporal bone fractures

A

longitudinal and transverse based on axis of temporal bone

33
Q

longitudinal temporal bone fracture

A

most common; aligned with axis of petrous portion of temporal bone

responsible for conductive hearing loss

may involve ossicles and facial nerve; risk for development of subsequent acquired cholesteatoma if tympanic membrane disrupted

34
Q

transverse temporal bone fracture

A

perpendicular to long axis of petrous portion of temporal bone

sensorineural hearing loss; involve bony labrinth

35
Q

petrous apex anatomy

A

medial portion of the temporal bone

borders surahyoid neck and intracranial compartment; contains Dorello’s canal (CN VI), Meckel’s cave (trigeminal ganglion), and petrous portion of ICA

36
Q

cholesterol cyst

A

foreign body giant cell reaction to cholesterol crystals; expansile mass with internal hemorrhage and fluid that does not suppress on fat suppression

37
Q

apical petrositis/petrous apicitis

A

rare complication of infectious otomastoiditis; infection extends into pneumatized petrous apex

38
Q

Gradenido triad

A

otomastoiditis, facial pain from trigeminal neuropathy at Meckel’s cave, lateral rectus palsy from CN 6 palsy at Dorello’s canal

vascular complications include thrombosis of ICA and dural veins

39
Q

petrous apex schwannoma

A

CN V, VII, VIII

smoothly expansile enhanscing mass with bony remodeling; may become cystic or contain fluid levels

40
Q

lancherhans cell histiocytosis/eosinophilic granuloma

A

neoplastic proliferation of eosinophils and langerhans cells

most common site of skull base involvement

destructive lesion with nonsclerotic margins

41
Q

chondrosarcoma

A

malignant neoplasm arises from midline clivus or off midline petroclival synchondrosis

ring-and-arc chondroid matrix; lobular cauliflower T2 weighted images

42
Q

chordoma

A

usually from clivus; may expand laterally to involve petrous apex

43
Q

Petrous apex lesions DDX

A

ACGMES MC

apical petrositis, congenital cholesteatoma, cholesteral granuloma, meningioma, eosinophilic granuloma, schwannoma,

mets/myeloma, chondrosarcoma/chordoma

CORE: Neuro (21 decks)

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