Temporal bone (Dr. Collins)

Question 1

Etiology of acquired EAC exostosis

Answer 1

Prolonged exposure to cold water and wind (surfer’s ear)

acquired conductive hearing loss

Question 2

Main differential consideration in suspected EAC exostosis

Answer 2

Osteoma

Question 3

Medial canal fibrosis is the pathologic end point of what disease processes (4)

Answer 3

Chronic otitis externa
Sequelae of surgery/trauma
Radiation
Autoimmune disease

Question 4

Pathogenesis of medial canal fibrosis

Answer 4

Fibrous tissue forms along medial aspect of bony EAC

Progresses to thick crescent of fibrous tissue along the lateral TM

Question 5

What is the tegmen?

Answer 5

Thin bony covering overlying the mastoid air cells and middle ear cavity

Question 6

How to do you determine the diameter of the vestibular aqueduct?

Answer 6

Measure at the midpoint (< 1.5 mm is normal)

Question 7

What are the contents of the pyramidal eminence?

Answer 7

Stapedius muscle

Question 8

Where does acquired cholesteatoma most commonly arise from?

Answer 8

Pars flaccida > pars tensa

Question 9

Etiology of cholesteatoma

Answer 9

Perforation of TM
Subsequent formation of inflammatory mass
Chronic epithelial and keratin proliferation

Question 10

Presentation of cholesteatoma

Answer 10

Painless otorrhea
Conductive hearing loss
Tullio phenomenon (noise induced vertigo)

Question 11

Treatment of cholesteatoma

Answer 11

Mastoidectomy and resection

Question 12

Which semi-circular canal is most affected by cholesteatoma?

Answer 12

Lateral semi-circular canal

Question 13

Classic MRI finding of cholesteatoma

Answer 13

Diffusion restriction

Question 14

Main difference between acquired and congenital cholesteatoma

Answer 14

Intact TM for congenital lesions

arises medial to the ossicles

Question 15

Differential of a vascular (red) retro-tympanic lesion

Answer 15

Glomus juguloympanicum
Aberrent ICA

NOT

• Glomus vagale (in the neck)
• Dehiscent jugular bulb (blue lesion)
• Cholesteatoma (white lesion)

Question 16

Vascular retro-tympanic lesions with pulsatile tinnitus

Answer 16

Aberrant ICA
Globus jugulare
Globus tympanicum

Question 17

Characteristic MRI finding of a glomus jugulare paraganglionoma

Answer 17

Salt and pepper appearance

highly vascular lesion with flow voids

Question 18

Main arterial supply of a glomus jugulare paraganglionoma

Answer 18

Ascending pharyngeal artery

pulsatile tinnitus, erosion of adjacent bone

Question 19

Diagnosis of dehiscence of the jugular bulb

Answer 19

Dehiscent sigmoid plate

High-riding jugular bulb

Question 20

Diagnosis of a high-riding jugular bulb

Answer 20

Can see the jugular bulb and IAC on same axial slice

Question 21

Classic MRI finding of Bell’s palsy

Answer 21

Unilateral enhancement of the proximal facial nerve

Question 22

Etiology of Bell’s palsy

Answer 22

Reactivation of HSV or zoster viruses

Question 23

Main differential for unilateral enhancement of the proximal facial nerve, aside from Bell’s palsy

Answer 23

Perineural spread of tumor

will be thicker and more nodular

Question 24

Function of superior petrosal nerve

Answer 24

Lacrimation

Question 25

Bony erosion of what structure causes superior semicircular canal dehiscence

Answer 25

Arcuate eminence

Question 26

Classic symptom of superior semicircular canal dehiscence

Answer 26

Tullio phenomenon (noise induced vertigo)

third window effect, allows pressure to influence the labyrinth