Tuesday, December 17, 2013

12/17/2103

12/17/2013

Answers:
As a treatment for Meniere Disease, intratympanic --- is absorbed into inner ear primarily be ---- window and selectively damages vestibular hair cells.
A) Tobramycin; oval 
B) Tobramycin; round 
C) Gentamicin; oval 
D) Gentamicin; round 
E) Amikacin; oval 
F) Amikacin; round

Gentamicin is believe to be absorbed primarily through the round window and selectively damage vestibular hair cells. Gentamicin can also decrease endolymph production be affecting dark cells in stria vascularis.

What are the four symptoms of Meniere Disease?

-Unilateral fluctuating SNHL
-Vertigo lasting minutes-hours
-Constant or intermittent tinnitus increasing in intensity before/during
vertiginous attacks.
-Aural fullness

MC Questions:
Vestibular suppressant are useful in treating the symptoms of vestibular neuronitis, however pts are advised to discontinue the use of these medications as soon as tolerable. Why?
A) Use of these drugs decrease central compensation 
B) These medications can become addicting 
C) Use of these medications has undesirable side effects 
D) Use of these medications can make symptoms worse 
E) More than one of the above are true

Free Response Question:
Describe the location and significance of "Donaldson's Line".

Quick Facts:
Superior Semicircular Canal Dehiscence
-Described by Lloyd Minor in 1998 = sound/pressure induced vertigo associated w/ bony dehiscence of superior semicircular canal.
-Pts have Tullio phenomenon.
-Also have symptoms w/ Valsalva maneuvers, or pressure changes (Hennebert Sign) or when ICP elevated.
Prognosis
-Due to exposure to external pressure along dehiscent superior canal transmitted to
inner ear.
-1% of temporal CT scans demonstrate significant thinning of this bone. Usually
bilateral.
Clinical Findings
-May be congenital but presentation is usually not until second decade.
-Can present w/ vestibular only, auditory only (rarer) or both.
-Pts report increased sensitivity to bone conduction sounds, hearing their pulse,
hearing their eye movement and autophony.
-”Inner ear conductive hearing loss” is common.
-Hearing loss is artifactual and mimc otosclerosis (low frequency CHL)...however, unlike otosclerosis, stapedius reflexes are present.
-Stapedius reflex w/ low-frequency CHL = imaging of inner ear to r/o dehiscence of the inner ear.
Imaging
-Use 0.5 mm collimated helical CT scans w/ reformation of the images in the plane of the superior canal.
Audio Testing
-low frequency CHL w/ stapedius reflex.
-Presentation of loud auditory signal may elicit typical symptoms of vertigo and eye
movement
Special Exams
-Frenzel glasses can be used, usually follow Ewald Lar.
-Nystagmus is in plane of canal and fast phase is toward stimulated canal.
-Lower than normal threshold for eliciting VEMP response.
Treatment
-Avoid stimulating stimuli.
-Correct diagnosis prevent unnecessary otosclerosis surgery.
-Can be treated w/ tympanostomy tube.
-If severe may require surgical repair of the dehiscence of the superior canal via
middle cranial fossa ro transmastoid approach.
-Symptoms may recur after surgery.
-Hearing loss after surgery is more common after revision.

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