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Audiology chap 6
Aud chap 6
| Question | Answer |
|---|---|
| Why might an objective test be used in the clinic setting? | Assess aud function in patients who cannot participate in behavioral testing, hearing screening for newborn, documenting abnormal function of aud system. |
| Who may not be able to participate in a subjective test? | Children, babies, cognitive deficits, difficult to test patient |
| Immitance | All-encompassing term to describe the measurements made of the tympanic membrane. Impedance, compliance, or admittance |
| Impedance | How much doesn't go through |
| Compliance | How well the eardrum moves and how much |
| Admittance | How much it lets through |
| T/F: Immittance can indirectly determine middle ear function based on tympanic membrane measurements? | True |
| Measurements of acoustic immittance meters (Middle ear analyzers) (3): | Static acoustic compliance, tympanometry, acoustic reflex (beyond middle ear space) |
| Impedance of any object is determined by... | frictional resistance, mass, and stiffness (paper vs cinderblock wall) |
| Resistance | Determined be the ligaments that support the three bones in the ME cavity |
| Mass | Determined primarily by the weight of the three bones and weight of the tympanic membrane |
| Stiffness | Determined by the load of fluid pressure from the IE on the base of the stapes |
| What frequency(s) does the miniature loud-speaker usually emit? | A PT around 220 or 226 Hz |
| Tiny microphone | Picks up the sound in the external ear canal |
| Air pump (pneumomotor) | Creates either positive or negative air pressure within the canal |
| What is a hermetic seal? | And airtight seal gained by using a rubber cuff around the probe |
| What are the two automatic measures used to measure in static acoustic compliance? | Equivalent volume of the EAM and mobility of the TM |
| What test produces similar results to static acoustic compliance? | Tympanograms |
| What is the C1 measure for SAC | Compliance of the outer ear and reflects the equivalent volume of the external ear canal |
| Normative values of C1 for children | 0.5cc |
| Normative values of C1 for for adults | 1.5cc |
| What is C2 for SAC | the compliance of the outer ear and middle ear combined |
| What is Cx for SAC | middle ear compliance |
| Normative values for Cx for SAC in children | 0.25-1.05 |
| Normative values for Cx for SAC in adults | 0.3-1.7 |
| What can fluid accumulation in the ME suggest? | a change in the stiffness, mass, or resistance of the middle ear system |
| What is tympanometry? | Measurement of the ME pressure, determined by the mobility (compliance) of th TM as a function of various amounts of positive and negative pressure in the external ear canal |
| Obtained values from a tymp.? | - Admittance/compliance of the TM - Tympanometric peak pressure (TPP) - Tympanometric width (gradient) - Peak compliance - Equivalent ear canal volume (Vea/ECV) |
| Tympanometric peak pressure (TPP) | where the peak is on the tympanogram and the pressure is |
| -Tympanometric width (gradient) | Halfway down from full compliance and measure the width on the x-axis |
| Peak compliance | How much is it moving when it is moving best? |
| Equivalent ear canal volume (Vea/ECV) | Space from tip of probe to eardrum |
| During the procedure of the tympanogram, what air pressure is the tympanic membrane brought to? | +200daPa and compliance is measured |
| T/F: successive measures of compliance are made as the pressure is decreased during a tymp. | True |
| What happens after the pressure has reached 0daPa? | Negative pressure is created by the pump and additional compliance measurements are made. Results are plotted on tymp |
| Typical adult and child peak compliance* | 0.3-1.5mL *Would expect children to be on the lower end |
| Typical adult and child peak pressure | +50 to -150daPa |
| Typical adult Vea | 0.9-2mL |
| Typical child Vea | 0.3-1.0mL |
| Typical adult and child tympanometric width | >150 is an issue |
| Type A Tympanogram results | -normal middle-ear function -Peak pressure near 0 daPa -Between .3-1.5 peak compliance -Pressure in eardrum and compliance is normal =Curve characterized by large inverted “V” |
| Type As Tympanogram results | -Shallow peak compliance, but normal ME pressure -Stiffness of the middle-ear system -TM moves but not as far as it should. Pressure is normal -Otosclerosis (main thing) or some fluid build-up in middle ear space (minor cause) -Goes with conductive HL |
| Otosclerosis | Build up of new bone around footplate of stapes and as bone builds, keeps stapes from pressing into the oval window and stiffens the system, chain reaction |
| What does fluid build up look on the tympanogram? | The gradient/ width on tympanogram is larger than normal |
| Type As helpful hint? | S= stiff or shallow |
| Type Ad tympanogram results | -High amplitude of curve, high compliance, eardrum moving more than it should (re-scales the y-axis) -Normal peak pressure -Potential separation of middle-ear bones (ossicular disarticulation) or tympanic membrane flaccidity -Large conductive HL |
| Ossicular disarticulation | Maybe caused by trauma or necrosis, frequent ear infections eating bone in middle ear and eventually brain RIP. Eardrum will push in a lot more than normal |
| Tympanic membrane flaccidity cause? | Membrane thinning, maybe through frequent ear infections |
| Type C tympanogram results | -Peak pressure below -150 daPa, lower than expected -Normal compliance -Reflection of negative pressure in the middle-ear cavity -Typically eustachian tube dysfunction (not opening or blocked), fluid will fill the ME space, bacteria party in tube |
| Type B tympanogram results | -No peak pressure or compliance reading -Tympanogram looks flat -Potential fluid in middle ear space, eustachian tube dysfunction, ear wax occlusion, or hole in the tympanic membrane -Always measure ECV to determine cause |
| What needs to be measured to determine cause of Type B results? | Ear canal volume |
| What is going on if the ECV is less than normal? | -Probably due to OE problem -Occlusion -Atresia -Can usually note these by doing otoscopy -If very small ECV (0.1 ml) probably have probe against canal wall due to really small ear canal |
| What can cause occlusion? | Ear wax, foreign object |
| What is atresia? | Congenital closure of a normally open ear canal, no opening to eardrum |
| If the ECV is normal | -Probably middle ear problem -Otitis media with effusion (OME)/(ME infection+fluid) -Not all people with OM have fluid completely filling the ME space, not all people with OM have Type B tympanograms |
| If ECV is greater than normal? | -Probably hole in eardrum -Measuring outer and inner ear space -Perforation (name or unnatural) -Pressure-equalization tube (PE tube) |
| What type of HL does a Type B tympanogram go with? | Conductive or mixed HL |
| T/F any type of "not normal" tympanogram goes with HL | True (with some exceptions) |
| What type of tymp will S/N HL have? | Type A |
| T/F you can get the place and cause of damage if it's beyond the ME during a tymp | False. It will appear normal if site of lesion is beyond what the test is testing. |
| Types of tymps for mixed hearing loss: | All except Type A, needs some type of conductive component |
| Tympanometry variants: | -High freq tymp -Multi freq tymp -Wideband Acoustic immittance -1000Hz tone (for infants super tiny ears) |
| What is a reflex? | An involuntary response to an external stimulus |
| Acoustic reflex? | Contraction of the stapedius muscle to (loud) sound. Stapedius muscle contracts reflexively and bilaterally in response to an intense sound presented to either ear. Causes tympanic membrane to stiffen and decrease in compliance |
| What is the stapedius muscle innervated by? | Cranial nerve VII |
| What is the acoustic reflex threshold? | the lowest level at which an acoustic reflex can be obtained. Acoustic reflexes can be recorded both ipsilaterally and contralaterally, bilateral reflex. |
| Louder the sound, ___ the reflex | greater |
| What level do bilateral reflexes happen for people with normal hearing? | Usually 70-100 dB SL re: threshold (70 abobe their threshold, 85dB SL) |
| What structures can the acoustic reflex measure/test? | Outer ear to the superior olivary complex (SOC), won't identify any problems further than that in the auditory tract. |
| Four possible acoustic reflex outcomes: The reflex may be ___ at a normal sensation level (about 85 dB SL, 70-100 range). | present |
| Four possible acoustic reflex outcomes: The reflex may be ___ at the limit of the reflex activating system (usually 110 to 125 dB HL). If at limits of machine, do not record anything and reflex reported absent | absent |
| Four possible acoustic reflex outcomes: The reflex may be ___, in the case of a hearing loss, but at a low sensation level (less than 60 dB above the audiometric threshold) if someone has reported hearing loss. | present |
| Four possible acoustic reflex outcomes: The reflex may be ___ but at a high sensation level (greater than 100 dB above the audiometric threshold). | present |
| T/F a muscle contraction (reflex) may be present in a conductive hearing loss, but may not be observed in the presence of an already stiffened TM or ME mechanism | True! |
| Mild to moderate cochlear HL expected at _____ ______ ______; severe cochlear HL expected to be _____. | lower sensation levels absent |
| Retrocochlear HL may have an ____ reflex or one ___ at a high SPL | absent present |
| What is an ipsilateral reflex? | Tone presented in the same ear as the reflex measured |
| What is a contralateral reflex? | Tone presented in one ear, reflex measured in the opposite ear |
| T/F the ear that is stated is always the ear in which the tone is presented? | True. Right ear ART: tone presented in right ear. |
| ARTs absent in reflex arc when ____ with a conductive problem | >40dB |
| ARTs ____ when the reflex arc ends in the ear with the conductive problems | absent |
| ARTs may be ___ when arc ends in "good" ear | present |
| If ____, ARTs present when reflex arc includes that cochlea | </=70 dB |
| If ___, ARTs absent when reflex arc includes that cochlea. Why? | >70 dB, most of the hair cells are dead and becomes a roadblock |
| ART pattern for retrocochlear problems? | ARTs absent when pathology exists in portions of CN VIII, VII, or brainstem involved in acoustic reflex arc regardless of degree of hearing loss |
| ART pattern for mixed hearing loss problems? | ARTs absent whenever reflex arc includes either or both portion of the mixed problem |
| ART pattern for central disorder problems? | ARTs present (issue beyond the reflex arc) because the reflex arc does not include the central auditory pathway |
| What is acoustic reflex decay? | Reflex decay is a gradual relaxation of muscle contraction in the presence of a continuing sound that elicits a reflex. |
| Is acoustic reflex decay normal for higher frequencies (2 and 4kHz)? | Yes |
| Acoustic reflex decay measures at which frequencies? | 500 and 1000 Hz |
| A reflex at 500 and 1000 Hertz elicited at (1)__ dB above the acoustic reflex threshold (ART) will maintain contraction fo (2)___ for normal ears and those with (3)___ hearing loss | 1. 10 2. 10 seconds 3. cochlear |
| T/F: The stapedius muscle stops contracting right after the sound is presented | False. It remains contracted for however long the sound is presented. |
| What is the definition of significant decay? | An at least 50% decrease in the original magnitude of the original contraction within a 10 second period |
| What is defined as abnormal acoustic reflex decay? | Decrease of 50% or more in the amplitude of middle ear compliance during the 10 second time period |
| Acoustic reflex decay is a sign of what problem? | Retrocochlear |
| Why are the results negative for acoustic reflex decay? | No significant decay present. Not a retrocochlear problem |
| Why are the results positive for acoustic reflex decay? | Significant decay present. It is a retrocochlear problem |
| When is decay typically seen? | When an acoustic tumor is present. It presses on the nerve and limits its firing speed over time. |
| What is an otoacoustic emission (OAE)? | The normal cochlea’s production of a sound response immediately following stimulation. Reflect activity of the outer hair cells |
| The conductive pathway must be ___ to obtain evoked OAEs | normal |
| Uses of OAEs include: | -Differential diagnosis of SNHL -Hearing screenings with infants or of hard-to-test patients -Monitoring of OHC function for high-level noise exposure/ototoxic drugs |
| Uses of OAEs also include: | -Early detection of false or exaggerated HL -Damage to cochlea shows up earlier on OAE than on pure tone testing, audiogram |
| Clinical applications of OAEs: | -Hearing screening of infants, pre-school children, and school age children. -Diagnosis of auditory dysfunction in children and adults. -Monitoring cochlear (outer hair cell) auditory function in patients receiving drugs that potentially damage the ear. |
| T/F OAEs can detect early on if there is damage in the ear dur to exposure to excessive levels of noise or music. | True |
| What is an SOAE? | Spontaneous otoacoustic emission |
| When does and SOAE occur? | When a cochlea produces sounds in the absence of an external stimulus. |
| Is SOAE the same at tinnitus? | NO. They do not hear the ringing sound as you do with tinnitus. |
| What is the typical frequency and amplitude range for SOAEs? | 1000-3000Hz and -10 to +10 dB SPL |
| What are TEOAEs? | Transient evoked otoacoustic emissions |
| What is the stimulus for TEOAEs? | Broadband clicks or tone pips (a transient sound) |
| Present in individuals with hearing thresholds ___. | <40 dBHL |
| What are DPOAEs? | Distortion-product otoacoustic emissions |
| Stimulus for DPOAEs? | Two primary pure tones varying in frequency by several hundredHZ (F1 and F2) |
| Multiple peaks along ___ ___ in reaction, then new peaks are formed along it due to the frequencies and get many sounds potentially coming back out | basilar membrane |
| What is the product of 2(F1)-F2? | Highest and loudest tone that can come out |
| Present in individuals with hearing thresholds___ to ___ , more sensitive cochlear function | < 40 to 50 dB HL |
| What does the presence of OAEs suggest? | There is very little or no conductive hearing loss caused by middle-ear abnormality. The responding frequency regions of the cochlea (OHC) are normal or exhibit no more than a mild hearing loss |
| What is the site of lesion if OAEs are present in SNHL and outer-hair-cell function is intact ? | Retrocochlear |
| What do absent OAEs confirm for SNHL pathologies? | Confirmation of cochlear issue but do not rule out possibilty of retrocochlear issues. |
| What do "present" OAEs mean? | The sound came back from the cochlea and was recorded by the probe |
| What do "absent" OAEs mean? | The sound did not come back or there was too little. |
| Are OAEs present with normal hearing? | Yes. |
| When are OAEs absent? | With any conductive component |
| Present for cochlear hearing loss if threshold is ____, but absent if threshold is greater than 40 dB HL. | ≤ 40 dB HL |
| When are OAEs present for retrocochlear issues? | Any time regardless of degree of HL |
| Are OAEs absent for mixed HL? | Yes, and will not know what the SN issue is |
| What are AEPs? | Auditory evoked potentials |
| What do AEPs test? | They analyze the electric activity of the brain when stimulated by acoustic stimuli using electrodes |
| Different tests of AEP? | -ECoG -ABR -AMLR -ALR |
| What is an ECoG? | Electrocochleography, measures of electrical responses from the cochlea to the inner ear |
| What is an ABR? | Auditory brain-stem response. Analyzes the integrity of the auditory brain-stem pathway using broadband clicks, tone pips, or bursts. |
| What is an AMLR? | Auditory middle latency response. Assesses middle latency responses, which occur between 15 and 60 milliseconds after signal presentation in midbrain. |
| What is an ALR? | Auditory late response. Assesses the late cortical auditory-evoked potential (CAEP), which includes responses that appear at least 60-300 milliseconds after signal presentation. -May be used for threshold estimation or speech-assessment procedures |
| What is the latency of an AEP? | the time elapsed between the introduction of a stimulus and the response |
| What is the amplitude of the AEP? | the strength, or magnitude, of the AEP |
| Uses of ECoG? | -Determining hearing sensitivity for difficult-to-test individuals -Neuro-otological applications -Enhancing the results of other AEP tests -0-2ms -Assisting in the diagnosis and monitoring of inner ear conditions such as Ménière’s Disease |
| Where are the electrodes placed for an ABR? | Forehead, lobes, or cheeks for infants. |
| Uses for ABR: | -Site of lesion for retrocochlear problem, to determine if cochlear or retrocochlear -Estimate pure tone thresholds (+/-10dB) -0-10ms |
| What do the waves represent for an ABR? | the neuroelectrical activity at one or more generating sites along the auditory brain-stem pathway |
| Where is wave I? | Cranial nerve VIII |
| Where is wave II? | Cranial nerve VIII |
| Where is wave III? | Superior olivary complex |
| Where is wave IV? | Pons, lateral lemniscus |
| Where is wave V? | Midbrain, lateral lemniscus, and inferior colliculus |
| Where is wave VI and VII? | Undetermined, don't have to know as much about these. |
| When is an ABR considered neurologically abnormal? | -Interpeak intervals are prolonged -Wave latency is significantly different between ears -Amplitude ratios are abnormal (normally Wave V is larger than Wave I) -Wave V is abnormally prolonged or disappears with high-click-rate stimulation. |
| When is an ABR considered neurologically abnormal (cont.)? | -If a problem with CN VIII, then won’t see a Wave I -ME infection with fluid, the latencies would be increased between the peaks |
| What is an ASSR? | Auditory steady-state response. An AEP used for threshold determination for children, useful alongside ABR testing |
| What do ASSRs evoke? | A steady-state neural response whose waveform follows the amplitude-modulated waveform of the ongoing stimulus |
| What stimuli is used for an ASSR? | frequency specific signals, such as pure tones. 2000-4000Hz range |
| Advantages of ASSRs? | Less time consuming than AEPs, not affected by patient's state of consciousness |
| What are AMLRs useful for? | Assessing the neurological function of the higher central auditory nervous system. There is pre and post test to see if auditory treatment has been helpful and see actual changes in the results. |
| Stimuli for AMLRs? | clicks, filtered clicks, or tone bursts |
| What state should the patient be in for AMLRs? | Calm but alert to minimize muscle twitching |
| Stimuli of ALRs? | frequency-specific, such as pure tone, short segments of speech (“dog test”) |
| What state should the patient be in for ALRs? | Attentive, a disadvantage when testing children. |
Created by:
ellicrandall
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