External Ear Flashcards
What is the incidence of congenital aural atresia
1: I 0,000 - 20,000.
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
1st branchial arch sinus, type 2.
What is the incidence of facial nerve displacement in congenital aural atresia
25 - 30%.
How is NOE treated
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.
Using the rating system developed by Jahrsdoefer, what score is associated with the best outcome after surgical treatment of aural atresia
8 or greater (80% chance of obtaining an SRT 15 - 25 dB).
What test should be used to assess auditory function in these patients
ABR.
In a patient with aural atresia and no evidence of SNHL, when should a CT scan of the temporal bones be obtained
Age 4 or 5.
What medication reduces the absorption of ciprofloxacin
Antacids containing calcium or magnesium salts.
What is tympanophonia
Audition of one’s own breath sounds.
What are the symptoms of patulous eustachian tube
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.
On CT imaging, which ear structures are best seen on axial views
Body of the malleus and incus, incudostapedial joint, and the round window.
Which has a male predilection
Both.
What does stenosis of the external auditory canal predispose to
Canal cholesteatoma.
How do patients with EAC cholesteatoma present
Chronic dull pain, usually unilaterally, with otorrhea and normal hearing.
How do patients with keratosis obturans usually present
Conductive hearing loss, acute severe otalgia, usually bilaterally; otorrhea is rare.
What imaging studies are used to diagnose NOE
CT scan with contrast, technetium-99m bone scan.
What are the two types of bony growths in the EAC
Diffuse exostoses and osteomata.
Which is more common
Exostoses.
Which is more likely to be bilateral
Exostoses.
Which is more likely to be seen in surfers
Exostoses.
What structure is most at risk during removal of a 1st branchial arch sinus
Facial nerve.
T/F: Surgery is contraindicated in children with unilateral atresia
False; many will operate if the patient is likely to achieve a residual conductive deficit of 30 dB or less.
What study is used to monitor the response to therapy
Gallium-67 scan.
What are the reasons for persistent conductive hearing loss after aural atresia repair
Inadequate mobilization of the ossicular mass from the atretic bone, an unrecognized incudostapedial joint discontinuity, or a fixed stapes.
Why is ciprofloxacin contraindicated in children
It has been shown to cause arthropathy of the weight-bearing joints in immature animals.
What is the term for a keratin plug occluding the EAC
Keratosis obturans.
What are the indications for removal of exostoses
Less than 1 mm aperature, recurrent otitis externa, water trapping.
What are the physical findings in a patient with EAC cholesteatoma
Localized erosion and periostitis of the posterior-inferior EAC associated with otorrhea.
Why is it particularly difficult to assess the auditory function in patients with bilateral atresia
Masking dilemma.
What advantage does hugging the middle fossa dura have on protecting the facial nerve
One will enter the middle ear first in the epitympanum; the facial nerve will always lie medial to the ossicular heads in the epitympanum.
Which is usually attached to the tympanosquamous suture line
Osteomata.
What is the typical presentation of an auricular endochondral pseudocyst
Painless, fluctuant outpouching on the upper anterior surface of the auricle, often preceded by low-grade chronic trauma.
What signs and symptoms are specific for necrotizing otitis externa (NOE)
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.
What factors are considered contraindications to correction of unilateral atresia
Poor mastoid pneumatization, anterior displacement of the middle ear, and facial nerve anomalies.
What is the most important factor in assessing the possibility of surgery in a patient with congenital aural atresia
Presence of the stapes.
When is surgery indicated in the treatment of NOE
Progression of pain despite aggressive medical therapy, persistence of granulations, and development of cranial nerve involvement.
What is the most causative organism of NOE
Pseudomonas aeruginosa.
What are some treatments for patulous eustachian tube
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.
What are the reasons for recurrent conductive hearing loss after aural atresia repair
Refixation of the ossicular chain or tympanic membrane lateralization.
How can one differentiate between relapsing polychondritis involving the ear and other causes of external otitis
Relapsing poiychondritis spares the lobule.
Which portion of the ossicular chain is least likely to be malformed in patients with congenital aural atresia
Stapes footplate.
On CT imaging, which ear structures are best seen on coronal views
Stapes, oval window and the vestibule.
Why is it difficult to treat infections involving the perichondrium or cartilage
The metabolic demands of cartilage are low, and its blood supply is hence diminished.
What are the 2 most important landmarks of the anterior approach
The middle cranial fossa dura superiorly and the TMJ anteriorly.
Why are diabetics more prone to NOE
The pH of their cerumen is higher and more conducive to bacterial growth.
What are the physical findings in a patient with keratosis obturans
Thickened TM, widened EAC medially, hyperemic canal skin with granulation tissue.
How does the infection spread from the external canal to the skull base
Through the fissures of Santorini.
Why should surgery be delayed until age 5
To allow for completion of pneumatization of the temporal bone.
What are the 2 basic approaches for repair of aural atresia
Transmastoid and anterior approaches.
T/F: A patient with a score of 5 or less is considered a very poor operative candidate
True.
Which cranial nerves are most commonly involved in NOE
VII (75%), X (70%), XI (56%).
Which wave of the ABR is ear-specific
Wave I.
