Exam 3 Flashcards
At which frequency levels do we conduct stapedial reflex threshold testing?
250, 500, & 1,000 Hz
Stapedial reflex threshold definition & values
Lowest dB level at which we see the muscle contract. Normally present at 65 to 70 dB above A/C threshold.
Stapedial reflex threshold is ______ in conductive hearing loss patients.
absent
Stapedial reflex threshold is _____ than normal in patients w/ cochlear lesions & _____ than normal in patients w/ neural lesions.
Cochlear: lower than normal (65-70 dB above threshold)
Stapedial reflex decay is significant in patients with ______ lesions
neural
Recruitment vs. Decruitment
Recruitment: more sensitive to loudness; cochlear lesion
Decruitment: less sensitive to loudness; neural lesion
At what level does the reflex pathway cross over?
Superior olivary complex
Stapedial reflex decay procedure
Test at 10 dB above stapedial reflex threshold, hold for 10 seconds. Significant if amplitude is reduced by 50% or greater during the first 5 seconds of stimulation (nerve becomes fatigued)
Where are the electrodes for ABR placed?
3 electrodes: one on top of head, one behind each ear
ABR provides information about hearing status between which frequencies?
1,000-4,000 Hz
Where do each of the 5 ABR waves come from?
I and II: auditory nerve
III: cochlear nucleus
IV: SOC
V: lateral lemniscus
Which wave tells us about the degree of loss?
V
Absolute latency for ABR
Wave I: 2 ms
Wave III: 4 ms
Wave V: 6 ms
Relative/interpeak latency for ABR
Between I to III and III to V: 2 ms
Between I to V: 4 ms
ABR profile for cochlear lesion or conductive hearing loss
Absolute latencies are prolonged/abnormal
Interpeak latencies are normal
ABR profile for neural lesion
Absolute latencies are prolonged/abnormal
Interpeak latencies are abnormal
OAEs test the function of what?
The outer hair cells
Why is OAE testing done at low intensities (38-40 dB)?
OHCs work primarily @ lower intensities (the stereocilia make contact w/ the tectorial membrane)
TEOAEs
Transient Evoked. Clicks or tonebursts at 1,000-4,000 Hz
DPOAEs
Distortion Product. Pairs of puretones. Give more reliable/valid results in noise (e.g., NICU).
What outer ear pathologies might cause conductive hearing loss?
Absence of pinna, closure of EAM, otitis externa, foreign objects in EAM
Otitis media w/ effusion
Fluid persists because of bacterial infection (acute cases are usually viral). Chronic if lasting for 4 months of longer.
What are some possible causes of OME?
Eustachian tube dysfunction, suppressed immune system, head-neck abnormalities, passive smoking, group day care attendance, socio-economic factors, & genetics.
Why are kids <5 more susceptible to OME?
Their eustachian tubes are shorter & straighter.
Why is passive smoking a risk factor for OME?
It causes vasoconstriction and increases blood viscosity, which deceases blood flow to the inner ear.
Tympanocentesis
Sampling the middle ear fluid to determine bacterial cause of infection
Myringotomy
ENT drains the fluid from the middle ear
PE tubes
Pressure equalization. Tiny valve placed in TM to help with eustachian tube dysfunction
What will the tympanogram of someone who has OME look like?
Type B (flat)
What will the tympanogram of someone who has otosclerosis look like?
Shallower than normal (type AS)
What will the tympanogram of someone who has eustachian tube dysfunction look like?
Type C - negative middle ear pressure, peak @ <-100
What causes otosclerosis?
Calcification of the stapes bone fixes it to the oval window
What will the audiometric profile of someone w/ otosclerosis look like?
Bilateral conductive HL w/ poorer B/C thresholds @ 2,000 Hz (AKA Carhart notch)
OAEs will be ______ in patients w/ conductive HL
absent
