External Ear Flashcards

1
Q

What is the incidence of congenital aural atresia

A

1: I 0,000 - 20,000.

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2
Q

What is the most likely diagnosis of a fistula 1 em anterior to the tragus associated with a cystic bulge in the anterior ear canal in an 8-month-old infant

A

1st branchial arch sinus, type 2.

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3
Q

What is the incidence of facial nerve displacement in congenital aural atresia

A

25 - 30%.

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4
Q

How is NOE treated

A

6 weeks of 2 different IV antibiotics directed against the organism cultured; alternatively, ciprofloxacin and rifampin for several months; hyperbaric oxygen is recommended for advanced NOE.

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5
Q

Using the rating system developed by Jahrsdoefer, what score is associated with the best outcome after surgical treatment of aural atresia

A

8 or greater (80% chance of obtaining an SRT 15 - 25 dB).

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6
Q

What test should be used to assess auditory function in these patients

A

ABR.

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7
Q

In a patient with aural atresia and no evidence of SNHL, when should a CT scan of the temporal bones be obtained

A

Age 4 or 5.

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8
Q

What medication reduces the absorption of ciprofloxacin

A

Antacids containing calcium or magnesium salts.

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9
Q

What is tympanophonia

A

Audition of one’s own breath sounds.

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10
Q

What are the symptoms of patulous eustachian tube

A

Aural fullness, autophony, tympanophonia that improve when the head is placed down between the legs; onset often occurs with weight loss or after irradiation to the nasopharynx.

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11
Q

On CT imaging, which ear structures are best seen on axial views

A

Body of the malleus and incus, incudostapedial joint, and the round window.

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12
Q

Which has a male predilection

A

Both.

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13
Q

What does stenosis of the external auditory canal predispose to

A

Canal cholesteatoma.

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14
Q

How do patients with EAC cholesteatoma present

A

Chronic dull pain, usually unilaterally, with otorrhea and normal hearing.

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15
Q

How do patients with keratosis obturans usually present

A

Conductive hearing loss, acute severe otalgia, usually bilaterally; otorrhea is rare.

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16
Q

What imaging studies are used to diagnose NOE

A

CT scan with contrast, technetium-99m bone scan.

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17
Q

What are the two types of bony growths in the EAC

A

Diffuse exostoses and osteomata.

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18
Q

Which is more common

A

Exostoses.

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19
Q

Which is more likely to be bilateral

A

Exostoses.

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20
Q

Which is more likely to be seen in surfers

A

Exostoses.

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21
Q

What structure is most at risk during removal of a 1st branchial arch sinus

A

Facial nerve.

22
Q

T/F: Surgery is contraindicated in children with unilateral atresia

A

False; many will operate if the patient is likely to achieve a residual conductive deficit of 30 dB or less.

23
Q

What study is used to monitor the response to therapy

A

Gallium-67 scan.

24
Q

What are the reasons for persistent conductive hearing loss after aural atresia repair

A

Inadequate mobilization of the ossicular mass from the atretic bone, an unrecognized incudostapedial joint discontinuity, or a fixed stapes.

25
Q

Why is ciprofloxacin contraindicated in children

A

It has been shown to cause arthropathy of the weight-bearing joints in immature animals.

26
Q

What is the term for a keratin plug occluding the EAC

A

Keratosis obturans.

27
Q

What are the indications for removal of exostoses

A

Less than 1 mm aperature, recurrent otitis externa, water trapping.

28
Q

What are the physical findings in a patient with EAC cholesteatoma

A

Localized erosion and periostitis of the posterior-inferior EAC associated with otorrhea.

29
Q

Why is it particularly difficult to assess the auditory function in patients with bilateral atresia

A

Masking dilemma.

30
Q

What advantage does hugging the middle fossa dura have on protecting the facial nerve

A

One will enter the middle ear first in the epitympanum; the facial nerve will always lie medial to the ossicular heads in the epitympanum.

31
Q

Which is usually attached to the tympanosquamous suture line

A

Osteomata.

32
Q

What is the typical presentation of an auricular endochondral pseudocyst

A

Painless, fluctuant outpouching on the upper anterior surface of the auricle, often preceded by low-grade chronic trauma.

33
Q

What signs and symptoms are specific for necrotizing otitis externa (NOE)

A

Persistent otalgia for longer than I month. Persistent, purulent otorrhea with granulation tissue for several weeks. Diabetes mellitus, another immunocompromised state, or advanced age. Cranial nerve involvement.

34
Q

What factors are considered contraindications to correction of unilateral atresia

A

Poor mastoid pneumatization, anterior displacement of the middle ear, and facial nerve anomalies.

35
Q

What is the most important factor in assessing the possibility of surgery in a patient with congenital aural atresia

A

Presence of the stapes.

36
Q

When is surgery indicated in the treatment of NOE

A

Progression of pain despite aggressive medical therapy, persistence of granulations, and development of cranial nerve involvement.

37
Q

What is the most causative organism of NOE

A

Pseudomonas aeruginosa.

38
Q

What are some treatments for patulous eustachian tube

A

Reassurance, weight gain, SSKI (1 0 gtt in juice po TID), Premarin nasal spray (25 mg in 30 cc NS, 3 gtt per nose TID), occlusion of the ET, and myringotomy and tympanostomy tube placement.

39
Q

What are the reasons for recurrent conductive hearing loss after aural atresia repair

A

Refixation of the ossicular chain or tympanic membrane lateralization.

40
Q

How can one differentiate between relapsing polychondritis involving the ear and other causes of external otitis

A

Relapsing poiychondritis spares the lobule.

41
Q

Which portion of the ossicular chain is least likely to be malformed in patients with congenital aural atresia

A

Stapes footplate.

42
Q

On CT imaging, which ear structures are best seen on coronal views

A

Stapes, oval window and the vestibule.

43
Q

Why is it difficult to treat infections involving the perichondrium or cartilage

A

The metabolic demands of cartilage are low, and its blood supply is hence diminished.

44
Q

What are the 2 most important landmarks of the anterior approach

A

The middle cranial fossa dura superiorly and the TMJ anteriorly.

45
Q

Why are diabetics more prone to NOE

A

The pH of their cerumen is higher and more conducive to bacterial growth.

46
Q

What are the physical findings in a patient with keratosis obturans

A

Thickened TM, widened EAC medially, hyperemic canal skin with granulation tissue.

47
Q

How does the infection spread from the external canal to the skull base

A

Through the fissures of Santorini.

48
Q

Why should surgery be delayed until age 5

A

To allow for completion of pneumatization of the temporal bone.

49
Q

What are the 2 basic approaches for repair of aural atresia

A

Transmastoid and anterior approaches.

50
Q

T/F: A patient with a score of 5 or less is considered a very poor operative candidate

A

True.

51
Q

Which cranial nerves are most commonly involved in NOE

A

VII (75%), X (70%), XI (56%).

52
Q

Which wave of the ABR is ear-specific

A

Wave I.