14 Ear Flashcards
What is Hitzelberger’s sign
Hypoesthesia of the postauricular area a/w CN 7 compression 2/2 vestibular schwannoma
“How can one differentiate between relapsing polychondritis involving the ear and other causes of external otitis?
RP will spare the lobule
“What is the likely diagnosis for someone who presents with vesicles on the pinna and external auditory canal (EAC), facial nerve weakness, and sensorineural hearing loss (SNHL)?”
Ramsay Hunt syndrome
What is lobule colobomata
Bifid lobule
What is cryptotia
Absence of the retroauricular helix
What is cockleshell ear
Type III cup ear where the ear is malformed in all directions
Why is it particularly difficult to assess the auditory fnc in pts with bilateral aural atresia
Masking dilemma (so you should use ABR)
What is Brown sign
Seen with glomus tympanicum tumors where the TM blanches when pressure is applied from the pneumatic otoscope
What is the definition of auditory threshold
Lowest level at which the pt can detect sound 50% of the time
Where is bone-conducted sound transmitted
directly to the cochlea
Which part of the auditory system is assessed by air conduction tests
The entire auditory system
What is the significance of a negative Rinne at 256 Hz, 512 Hz, and 1024 Hz?
At least a 15 dB CHL, 25-30 CHL, and 35 CHL respectively
What percent of the time will the Rinne test miss and air bone gap < 30 dB
50%
“A patient has a negative Rinne at 256 Hz AS. At 512 and 1024 Hz, it is positive as it is at all three frequencies AD. The Weber test lateralizes to the left at all three frequencies. He hears a soft whisper AD and a soft to medium whisper AS. What is his hearing loss?”
15 dB CHL AS
“What is the significance of the ability to hear a tuning fork placed on the teeth?”
Indicates that cochlear reserve is present and surgery may be beneficial
How are air and bone thresholds measured?
By first obtaining a positive response, then lowering the intensity by 10 dB increments until no response is obtained
What are the stimuli used to obtain a speech reception threshold (SRT)
Spondees - 2 syllables with equal emphasis on both syllables
How is SRT measured
“By starting at minimal intensity and ascending in 10 dB increments until the correct response is identified.”
What is the definition of SRT
The lowest hearing level at which half of the words are heard and repeated correctly, followed by at least two correct ascending steps
“SRT should be within ___ dB of pure tone average (PTA).
10 dB
What is the speech detection threshold (SDT)?
Hearing level at which 50% of the spondaic words are detected; usu 6-7 dB lower than the SRT
How is speech discrimination testing performed
Phonetically balanced monosyllabic word lists (50) are administered 30-50 dB above threshold and the correct percentage is identified
What is a nl word recognition score
90-100%
What is the significance of speech discrimination scores?
Pts w/ cochlear and retrocochlear pathology will have poor to very poor scores, respectively. Those with only CHL will have nl scores when the intensity level is sufficiently loud.
What is rollover
A decrease in speech discrimination scores when presented at higher intensities; suggestive of a retrocochlear lesion.
“A patient with an SRT of 55 dB HL and a speech discrimination score of 64% at 75 dB HL has what kind of hearing loss?
SNHL
What is interaural attenuation
The reduction of sound when it crosses from one ear to the other
What is nl interaural attenuation of air-conducted tones
40-80 dB depending on whether ear inserts or headphones are used and also on the freq being tested
What is the nl interaural attenuation value for bone conduction
0 dB
When should masking be used
When the air conduction threshold of the test ear exceeds the bone conduction threshold of the nontest ear by a value greater than interaural attenuation
What should you mask with
Narrow band around the frequency you are testing***
What is crossover
The attained responses represent the performance of the nontest ear rather than the test ear due to a large sensitivity difference b/w the ears
When does the masking dilemma occur
Bilateral 50 dB or greater air-bone gaps
What is the Stenger’s test
Test to see if the patient is malingering; appropriate to administer if there is a >20 dB difference b/w ears in voluntary thresholds
Where is the peak pressure point in a nl tympanogram in an adult
Between -100 and +40 daPa
What would the tympanogram look like in an ear with an interrupted ossicular chain
Very steep amplitude, high peak (type Ad)
What is the acoustic reflex threshold
The lowest stimulus level that elicits the stapedial reflex
In the nl middle ear, contraction of middle ear muscles occurs at which pure tones
65-95 dB HL
What are the neural pathways of the acoustic reflex
- -VIII to the ipsilateral ventral cochlear nucleus to the trapezoid body to the motor nucleus of VII to VII to the ipsilateral stapedius.
- -VIII to the ipsilateral ventral cochlear nucleus to the trapezoid body to the ipsilateral medial superior olive to the motor nucleus of VII to VII to the ipsilateral stapedius.
- -VIII to the ipsilateral ventral cochlear nucleus to the medial superior olive to the contralateral motor nucleus of VII to the contralateral VII to the contralateral stapedius
T/F: The acoustic reflex threshold is absent in pts with middle ear dz
True
What does the finding of an elevated acoustic reflex in the presence of nl hearing or mild SNHL and a nl tympanogram suggest
Retrocochlear pathology
T/F: Brainstem lesions may abolish the acoustic reflex w/o affecting the pure tone thresholds
True
What does acoustic reflex delay measure
The ability of the stapedius muscle to maintain sustained contraction
How is acoustic reflex delay measured
A signal is presented 10 dB above the acoustic reflex threshold for 10 seconds; if the response decreases to 1/2 or less of the original amplitude w/in 5 sec, the response is considered abnl and suggestive of retrocochlear pathology
What 3 audiometric test techniques are used to obtain behavioral response levels from a child
- Behavioral observation audiometry
- Visual reinforcement audiometry
- Conditioned play audiometry
What stimulus is used to evoke the ABR
A simple acoustic click, b/w 2000 and 4000 Hz
What do the peaks of the ABR represent
Synchronous neural discharge at various locations along the auditory pathway
What does each wave of the ABR represent
I -- 8th nerve II -- cochlear nucleus III -- Superior olivary complex IV -- Lateral lemniscus V -- Inferior colliculus (E. coli)
Which ABR wave is the largest and most consistent
V
T/F: The ABR is unaffected by state of sleep or meds
True
How is ABR m/c used
To test newborns, difficult to test kids, and malingerers
How is hearing threshold estimation performed using ABR
Wave V is tracked with decreasing sound intensity until it can no longer be observed
What does ABR interwave latency reflect?
The time necessary for neural info to travel b/w places in the auditory pathway; any pathology that interferes with this transmission will prolong the latency
When is the interaural latency difference of wave V important
Used to document retrocochlear pathology when wave I is absent
When is wave I absent
When hearing loss exceeds 40-45 dB at higher frequencies
When determining interpeak latencies, which waves are compared
I-III, I-V
What is the difference in these interpeak latencies
Increased I-III intervals are almost always indicative of retrocochlear pathology, whereas increased I-V intervals is more likely a/w noise induced SNHL
How will a retrocochlear lesion affect the ABR
Prolongation of absolute wave V latency, I-V latency, and interaural wave V latency
What are 3 types of evoked OAEs
- SFOAE (stimulus frequency)
- TEOAE (transient evoked)
- DPOAE (distortion product)
Which of these is evoked by two pure tones
DPOAE
?2f1-f2
What are the typical objective auditory findings ini pts with auditory neuropathy
- Decreased or absent ABR
- Nl OAEs
- Absent auditory reflexes
- Very poor speech discrim
- Mild to profound pure tone HL
Why are OAEs useful as a screening tool in infants
Nearly 100% of people demonstrate evoked OAEs; testing is noninvasive and inexpensive; test time is short; cochlear hearing loss exceeding 30 dB can be detected.
If otoacoustic emissions are present, can retrocochlear pathology be ruled out
No
What test can be used to exclude the absence of aidable hearing when the ABR is absent at maximum levels
ASSEP (auditory steady state evoked potentials)
T/F: ASSEP has little predictive value for hearing levels in kids with auditory neuropathy
True
T/F: ASSEP cannot distinguish b/w cochlear and retrocochlear hearing loss
True
What are the indications for hearing screening in neonates if universal screening is not available
- FMH hereditary childhood SNHL
- Congenital perinatal infxn (TORCH)
- Head or neck malformation
- Birth wt <1500g
- Hyperbilirubinemia requiring exchange transfusion ( > 20)
- Bacterial meningitis
- Apgar 0-4 at 1 min or 0-6 at 5 mins
- Prolonged ventilation (>5 days)
- Ototoxic meds
What are the indications for performing hearing screen in infants 29 days to 2 years
- Parent concern.
- Developmental delay.
- Bacterial meningitis.
- Head trauma associated with loss of consciousness or skull fracture.
- Ototoxic medications.
- Recurrent or persistent otitis media with effusion for at least 3 months.
What are indications for hearing eval every 6 months until age 3
- FMH hereditary childhood hearing loss
- In utero infxn (TORCH)
- Neurodegenerative d/o
What does the audiogram typically look like in a child with SNHL 2/2 rubella
cookie-bite pattern
In the w/u of congenital hearing loss, what test has the highest diagnostic yield
CT scan
What sort of hearing loss is m/c in pts with Cogan’s syndrome
progressive to total deafness
In pts with COM but no cholesteatoma, what level of HL is a/w ossicular chain disruption or fixation
30 dB or more
What is the significance of HL in absence of middle ear effusion in pts with congenital cholesteatoma
Most lesions begin anterosuperiorly and extend posteriorly with growth. Hearing loss indicates posterior extension with involvement of the stapes suprastructure and/or the lenticular process of the incus
What auditory tests are performed in tinnitus analysis
- Pitch matching
- Loudness matching
- Minimum masking level (MML)
- Residual inhibition
How is the dx of idiopathic intracranial hypertension syndrome made
Exclusion of lesions producing intracranial hypertension, lumbar puncture with CSF pressure >200 mm H20 and nl CSF constituents
What percent of pts with IIH will have an abnl ABR
1/3
In pts with IIH, what is the usual pitch of tinnitus
Low frequency
What maneuvers on PE will decrease or completely eliminate pulsatile tinnitus of venous origin
- Light digital pressure over the IPSI IJ
- Head turn to IPSI side
What instrument is most helpful in examining nystagmus on PE
Frenzel goggles
What d/o are a/w down-beating nystagmus
- Arnold-chiari
- CBL degeneration
- MS
- Brainstem infarct
- Li intoxication
- Mg and thiamine deficiency
What d/o are a/w up-beating nystagmus
- Brainstem tumors
- Congenital abnormalities
- MS
- Hemangiomas
- Vascular lesions
- Encephalitis
- Brainstem abscess
What d/o are a/w bidirectional gaze-fixation nystagmus
Barbiturate, phenytoin, and etoh intoxication
What findings on VNG are seen with central vestibular d/o
Disconjugate eye movements, skew deviation, vertical gaze palsy, inverted Bell’s phenomenon, seesaw nystagmus, bidirectional nystagmus, periodic alternating nystagmus, and nystagmus that is greater with eyes open and fixed on a visual target than in darkness.
What finding on VNG is pathognomonic for a lesion at the craniocervical junction
Spontaneous downbeat nystagmus with the eyes open, in the primary position that increases with lateral gaze or head extension
What is opsoclonus
Rapid, uncontrolled, multivectorial, conjugate eye mvmt, usu seen on PE and difficult to detect on VNG
What does computerized dynamic platform posturography specifically measure
postural stability and sway
What features distinguish BPPV from vertigo due to CNS dz
CNS: no latent period, direction of nystagmus varies, N/V are nonfatigable
What is measured in electrocochleography (ECOG)
Cochlear microphonic action potential (CM), action potential of VIII (AP), and summating potential (SP), and compound action potentials
Where are ECOG recording electrodes placed
As close as possible to the cochlea and auditory nerve (promontory, TM, EAC)
When comparing the summating potential to the compound action potential, what value is considered abnl in an ECOG and what does that suggest
A ratio >= 0.45; Meniere’s
What technique can be used to differentiate the ECOG SP from the nerve potential of VIII (AP)
AP is a neural response that will respond to higher rates of stimulation. SP is a preneural response that is not affected by higher rates of stimulation. Therefore, increasing the click rate of the stimulus will affect the AP but not the SP.
What is “Schwartze’s sign”
Reddish hue on promontory a/w otosclerosis
Is acoustic reflex present in pts w/ otosclerosis
Usu absent bilaterally even if dz is unilateral
Is the acoustic reflex present in pts with SSCD
yes
What is Tullio’s phenomenon
Vertigo with loud noise (commonly seen in SSCD)
How does the hearing impairment from malleus ankylosis differ from that of otosclerossi
In pts with malleus ankylosis, hearing impairment is mostly unilateral (78%); the air bone gap is smaller (usu <20 dB); SNHL is more freq, particularly at 4 kHz; acoustic reflex more likely to be present on the CONTRA ear and absent on the IPSI ear
