Otology Flashcards
Masking dilemma
occurs when there is bilateral 50 dB air-bone gap
Stenger test
Tester presents subthreshold tone in “bad” ear and suprathreshold tone in “good” ear
Recruitment
abnormal growth in loudness that indicates a cochlear lesion
Fatigue
Change of auditory threshold resulting from continued acoustic stimu-lation that indicates retrocochlear lesion
Rollover
a decrease of word recognition at high intensities (from cochlear distor-tion of eighth nerve adaptation) and is a classic finding for retrocochlear lesions
Type As tymp
“S”hallow
Seen in otosclerosis, tympanosclerosis
Type AD tymp
“D”eep
Seen in ossicular discontinuity
Acoustic reflex pathway
Cochlea → CN VIII → cochlear nuclei and contralateral olivary complex via the trapezoid body → motor nucleus of CN VII → stapedius
Degree of CHL to affect acoustic reflex
40 dB for the ear receiving the reflex-eliciting tone - or -
as little as 10 dB for the probe ear
Degree of SNHL to affect acoustic reflex
> 70 dB
When can ABR first detect brain-stem function
When is maturity reached on ABR
28 weeks’ gestational age with the appearance of waves I, III, and V
18 months after birth
ABR waves
EECOL
I: distal Eighth nerve II: proximal Eighth nerve III: Cochlear nucleus IV: Olivary complex V: lateral Lemniscus
ABR normal latencies
I-III =2.3 ms
III-V = 2.1 ms
I-V = 4.4 ms
Retro-cochlear lesion on ABR
interpeak latency difference greater than 4.4 ms
Interaural latency difference of wave V greater than 0.2 ms
V3-V5 latency of greater than 2.1 ms
Electrocochleography (ECOG), diagnostic for Ménière’s disease
elevated (> 0.4)
ratio of the summating potential to the compound action potential
Distortion product otoacoustic emissions (DPOAEs) uses (3)
newborn hearing
aminoglycoside induced hearing loss
to help differentiate between cochlear and retrocochlear causes of SNHL
Auditory neuropathy — OAEs
normal OAEs
abnormal CNVIII
Hennebert sign
= Vertigo with pressure changes
Ménière disease’s
peri-lymph fistula [PLF]
superior canal dehiscence
syphilis
Tullio phenomenon
Noise-induced vertigo
Ménière’s disease
PLF
superior canal dehiscence
syphilis
Nystagmus fast vs slow phase driving force
Slow
Jahrsdoerfer criteria for surgical repair of atresia (9
Stapes: 2
Oval window open: 1
Round window open: 1
Middle ear space: 1
Pneumatized mastoid: 1
Normal CN VII: 1
Malleus and incus: (minus) −1
Incus and stapes: 1
External ear: 1
Microtia types
I — mild deformity
(ie, lopear, cupear, etc)
II — all structures are present to some degree, but there is a tissue deficiency
III — ”Classic”
significant deformity with few recognizable landmarks
- lobule often present and anteriorly displaced
- canal atresia
Frostbite
Rapidly rewarm with gauze soaked in saline, that is, 38°C to 42°C/100.4°F to 107.6°F
Tissue should not be debrided upon rewarming as demarcation may take several weeks
topical antibiotic, ointment, and oral analgesics
Malignant OE, Dx
Technetium99 radioisotope scan
followed with gallium scan
Hereditary hearing loss, syndromic vs non-syndromic %
<1% of kids
70% NON-syndromic - 80% recessive -- MCC = connexin 26 or GJB2 - 20% dominant < 2% X or mitochondrial
30% syndromic
