Audiometric Principles 2
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why do we mask?
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-determine type of HL -evaluate hearing in test ear
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acoustic reflexes
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-suggest site of lesion or retrocochlear disorder -can be affected by ME disorders, HL in stimulus ear or interruption of neural innervation of stapedius muscle
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OAEs
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-assess aud function up to level of OHCs
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conductive HL
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-loss of hearing sensitivity caused by blockage of sound before sound gets to ear (ear canal or ME)
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examples of CHL
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-wax blockage -fluid in ME -break in ossicular chain -tumor in ME
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symptoms of CHL
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-sound too soft -loss worse in LF -may experience occlusion effect -sometimes hear better in loud noisy environments -medically treatable
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treatment of perf
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-usually heals spontaneously -due to repeated infections--> probs won't heal on own
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surgery option for perfs
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-myringoplasty=paper patch -tympanoplasty=formal skin
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evidence of prior perf
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-tympanosclerosis=scarring, white patch on TM -monomeres=false TM, incomplete healing
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cochlear HL
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-damage to IE -nerve impulse not generated due to loss -damage to hair cells
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symptoms of cochlear loss
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*bilateral* *HF hearing affected first* -speech sound muffled -speech not always easier to hear if louder *distortion* -tinnitus -dizziness rarely present
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what is a hallmark of cochlear loss?
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recruitment
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recruitment
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abnormal growth of loudness -dynamic range shrinks *normal loudness perception in an impaired ear*
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retrocochlear HL
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-damage to retrocochlear structure in 8th nerve or brainstem
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symptoms of retrocochlear involvement
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-person has both cochlear & retro damage *unilateral* -loss mild to severe -sound distorted or unclear *tinnitus & dizziness common* -won't have recruitment -HA not appropriate
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SNHL
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-can't always distinguish cochlear & retro -damage in IE & beyond
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mixed HL
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-CHL component & SNHL component -can be in TM, OE, ME, retro
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determining site of lesion
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-where pathology is to decide if medical eval needed -should be included in every report
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need for medical eval
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-based on history, physical exam, rest results -have condition that can improve with medical treatment or worsen without treatment
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report
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-every report should include prognosis -history -physical exam -test results -limitations
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FDA criteria for medical referral
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-visible congenital/traumatic deformity of ear -active drainage within past 90 days -sudden/progressive HL within past 90 days -acute/chronic dizziness -pain/ discomfort in ear
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what should we expect with normal otoscopy?
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Type A Tymp normal ART OAEs may not be present not conductive or mixed HL
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physical exam of external ear
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-skin lesions, infection -malformations, atresia, size, growth tags -trauma, surgical scars -position/angle of pinna -stenosis/ collapsible canal
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course of ear for otoscopy of ear canal
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anterior-superior, posterior, anterior inferior
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what would the test results be for scar tissue?
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-less compliant TM -normal or not present AR -reduced, diminished, robust OAEs -CHL, WNL
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what would the test results be for TM retraction?
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Type B Tymp absent AR absent OAEs CHL
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what would the test results be for otitis media?
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Type B tymp, reduced compliance absent or elevated AR & OAEs CHL
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what would the test results be for cholesteatoma?
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-normal tymp -normal AR -normal OAEs -WNL as grows can become big problem, canal wall up or down surgery
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glomus tumor
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-abnormal growth of glomus body (vein, blood vessel) -red TM -pulsatile tinnitus -refer to ENT
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causes of TM perf
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-trauma -ear infection
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ear infections causing perf
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-pressure of pus/fluid behind TM -repeated ME infections
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what would the test results be for perforations?
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-high EC volume on tymp -elevated AR -diminished/present OAEs -CHL
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when is stenger test used?
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-asymmetric air conduction thresholds -questioning organic aspect to loss -estimate accurate threshold -conduct immediately upon ID for need
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audiometric configuration needed for stenger test
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-asymmetric loss of at least 20dB HL -PT threshold -SRT
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how does stenger test work?
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-present same signal in both ears at same time -listener will only perceive sound in ear which it is loudest or has highest SL -no patient instructions
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stenger formula?
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better ear: threshold + 10 dB SL worse ear: threshold - 10 dB present stimulus to both ears at same time -either AC thresholds or speech thresholds used
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positive stenger test
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-no response -can use to establish estimate or accurate threshold -patient is lying
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negative stenger test
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-patient response they heard sound -patient not lying
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masking
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elevation in threshold of 1 signal produced by into of 2nd signal
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clinical masking
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-masking elevates threshold in NTE -want ear specific info
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cross over and need to mask
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-when present signal to TE, may cross over to NTE -could result in shadow curve if left unmasked ex. ear phone leakage & BC
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when do we need to mask?
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-when unmasked threshold in TE is greater than IA for transducer in use when referencing BC threshold of NTE
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what do negative or flat tymps suggest? (type B, C, Ad)
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-CHL -bone thresholds better (0)
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what do normal tymps suggest? (Type A)
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-SNHL -bone should match air thresholds
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interaural attentuation
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-reduction in sound energy of a signal as it is transmitted by BC from 1 side of head to opposite ear -all kinds of stimuli can result in IA
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effective masking
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-intensity in dBHL that a PT can be masked by given level of noise -amount of masking needed to just mask an auditory stimulus
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under-masking
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-when noise presented to NTE is not sufficient to keep from contributing
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IA for headphones
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40 dB
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IA for bone vibrator
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0-10dB
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IA for inserts
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60dB
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sufficient masking
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-when noise presented to NTE is enough to keep it from contributing to response & not intense enough to influence ability of TE to respond
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overmasking
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-when noise presented to NTE is intense enough to cross over to TE and mask it -causes TE thresholds to be elevated
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masking rule
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-masking using NBN is needed when TE AC threshold exceeds NTE by 40dB or more -TE AC threshold exceeds NTE BC threshold by 40dB or more
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plateau method of masking
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-start level= 15dB above AC threshold of NTE -determine point of overmasking -re-est AC TE threshold -raise masking noise level 5dB present test tone at new threshold -increase masking another 5 dB & present test tone at new threshold again -continue until new threshold does not change for 3 consecutive 5dB masking increments
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masking dilemma
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-when plateau is never reached -when initial masking level will reach or exceed IA for your transducer making you unable to plateau without over masking TE (more likely to occur with AU CHL)
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AC masking
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-performed with ear phones or inserts
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BC masking
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-performed with bone oscillator & earphone/insert on NTE only
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masking rules for BC
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-masking needed when AC threshold exceeds an unmasked BC threshold by more than 10dB -plateau method similar to PT AC but must account for occlusion effect
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occlusion effect for BC
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250Hz=20dB 500Hz=15dB 750Hz=10dB 1000Hz=5dB
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masking BC formula
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AC NTE + 15dB + OE
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purpose of speech masking
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-remove influence of NTE to est accurate SRTs & WRS for the TE
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masking for speech is always calculated based on?
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AC threshold of NTE -want to prevent crossover by BC but have to make masking noise audible so it must be SL above air threshold
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speech masking method
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-no plateau, just add a number -determine need for masking by estimating BC of NTE at 500Hz, 1kHz, 2kHz -if difference in presentation level referencing best bone thresholds is IA value then must mask for word rec and possibly retest SRT
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speech masking level
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-presentation level for TE - 35dB + largest A/B gap of NTE *presentation level - 20dB= masking level*
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if numbers do not match up after thresholds are determined.....
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RE-TEST
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conductive HL in NTE for speech masking
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add additional masking equal to largest A/B gap -reduces effectiveness of masking noise presentation level for TE - 35dB + largest AB gap of NTE
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Katz Method AC Masking
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-determine need for masking & point of overmasking using conventional method -add 30dB to AC threshold of NTE -re-est threshold of TE -if threshold shifts by 10dB masking level was in plateau & threshold est -if threshold shifts by 15dB or more, increase masker by 20dB & re-est threshold
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Turner Optimized AC Masking
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-determine need for masking -set initial masking level to AC threshold of TE-10dB & re-est threshold of TE -determine shift in threshold due to masker (present tone in TE until heard) -increase masking level the same amount you increased tone & re-est threshold -if threshold does not shift, masker is in plateau -if threshold shifts, keep increasing masking level same amount
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site of lesion
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-where is abnormality -every eval report must include it
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what are the old tests for site of lesion based on?
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psychoacoustic principles
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ABLB-Alternate Bilateral Loudness Balance Test
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-asymmetry requirement: IE at least 20dB poorer than normal ear -perception of loudness may be similar -present tones alternately to ears under transducer -good ear is reference -impaired ear is variable ear
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ABLB-Alternate Bilateral Loudness Balance Test Procedure
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-alternate tones between ears -in ref ear, set tone to 20dBSL -ask patient to tell when tone in variable ear is equal in loudness to tone in reference ear -adjust intensity & mark on laddergram raise intensity in reference ear 20dB & repeat -repeat until tolerance levels/LDLs approached
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general principle of ABLB-Alternate Bilateral Loudness Balance Test
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-whether recruitment is present/absent -compares loudness growth between ears *must have normal hearing in 1 ear* -intensity increases above threshold required to produce sensation of equal loudness are much less for impaired ear than normal ear
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ABLB-Alternate Bilateral Loudness Balance Test Interpretation of Laddergram
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-Complete or partial recruitment= cochlear pathology (OHC damage) -derecruitment: retro path (rare), better ear less sensitive to increasing intensity -no recruitment: dB level between ears constant -complete recruitment: equal loudness occurs at equal intensities -partial recruitment: decrease in stimulus intensity diff between 2 ears but equal loudness for equal intensities is not reached -less clear: possible cochlear loss
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diagnosis for ABLB-Alternate Bilateral Loudness Balance Test
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-recruitment has been reported in 73% to 100% ears with cochlear HL -tumors can compromise blood flow in cochlea -hair cell loss/dysfunction -decoupling of stereocilia from tectorial membrane -8th nerve function physiological diff between OHC & IHC -CNS mechanisms -33-90% decruitment in 8th nerve tumors
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physophysical methods for ABLB-Alternate Bilateral Loudness Balance Test
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-method of limits: clinician controls intensity of both reference & variable tone (client tells clinician what to do) -method of adjustments: clinician controls ref intensity, client controls variable intensity (faster & less confusing for patient)
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advantages of ABLB-Alternate Bilateral Loudness Balance Test
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-effective test for recruitment -detects cochlear disorder -easy & quick
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disadvantages of ABLB-Alternate Bilateral Loudness Balance Test
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-cannot be administered in bilateral HL cases -less effective in detecting retro path
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diplacusis
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-a diff in hearing by 2 ears so 1 sound is heard as 2 -either in time or pitch so 1 sound is heard as 2
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MLB-Monoaural Loudness Balance Test
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-done in 1 ear using 2 frequ with pulsed tones alternating between frequ -normal hearing at 1 frequ with 20-25dB diff in threshold between frequ -hard task-high subject variability -difficult to interpret usually just report presence or absence of recruitment
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SISI-Short Increment Sensitivity Index
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-evaluates patient ability to detect small changes in intensity -patient hears carrier tone onto which superimposed periodic increases in intensity -intensity increase increments controlled by audiologist
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Traditional SISI
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-presented at low dBSL -for normal hearing patient, OHC will be activated & ability to hear small changes in intensity will be poor -for patients with cochlear, OHCs are damaged & 20dBSL activates IHC & ability to hear small changes in intensity is good
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SISI Procedure
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-train: present 20dBSL carrier tone to impaired ear for brief period -superimpose onto that tone periodic 5dB increments of increased intensity at same frequ -patient presses button when increased intensity detected -decrease to 2dB -test phase: reduce intensity of superimposed tone to 1dB every 5sec for 20 increments for each ear *# of increases heard x 5= score*
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SISI interpretation
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-70% correct or greater=cochlear pathology -tumors compromising blood flow to cochlea & other factors like noise exposure & aging -30% or less=negative for cochlear pathology -30-70%=not strongly diagnostic/inconclusive *patients with cochlear loss <50-60dB score*
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High Intensity SISI
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-75dBH HL carrier level for losses 60dB HL -test in 2000-4000Hz >70%=normal cochlear function or cochlear path <25%=retro
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adaptation & tests of SISI
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-when heard uninterrupted for period of time, intensity of tone diminishes -for patients with retro lesions, adaptation occurs more quickly -result of poor neural recover
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advantages of SISI
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-easy & quick -sensitive to cochlear pathology
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disadvantages to SISI
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-predictive accuracy of 8th nerve low -conflicting reports of effectiveness -used as part of battery of tests -limited understanding of physiological basis
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Cahart's Threshold Tone Decay Test
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-present steady PT at person threshold -patient pushes button as long as hear one -if heard for 60 seconds, test done -if tone becomes inaudible raise intensity 5dB without turning off tone -if heard for 60seconds stop if not raise another 5dB -continue until patient hears tone for 60 sec at 1 intensity or level reaches 30dB SL
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interpretation of Cahart's Threshold Tone Decay Test
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decay >30dBSL=retro path -large tumors caused positive decay in 63% cases -small tumors 14% -MS, neuritis & aging can also cause positive
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Olsen Noffsinger tone Decay
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-similar to Cahart's except start level is 20dBSL -frequ at 500 & 4000Hz >30dBSL=retro
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Rosenburg Tone Decay Test
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-considered screening test -tone presentation level is 5dBSL -raise tone intensity whenever inaudible -stop test at end of 60 sec -interpretation same as Cahart's procedure decay >30dBSL=retro path
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Owens Threshold Tone Decay
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-tone presentation starts at 5dBSL -if tone decays before 60 seconds stimulation discontinued for 20sec before intro of tone at 5dB increment -continue process until patient hears tone for 60sec or level of 20dbSL reached -measure amount of tone decay & time to inaudibility
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Test Result classification for Owens Threshold Tone Decay
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-Type 1= normal ears= no tone decay -Type 2= cochlear pattern= time to inaudbility increases when signal level increases -Type3= Retrocochlear= time to inaudibility not affected by increases in signal level
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Interpretation of Results for Owens Threshold Tone Decay
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-retrocochlear= shows decay at all frequ, decay does not change with increases in intensity, not hearing for all 60sec -cochlear= 1 or 2 frequ show decay & decay slower as intensity increased
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Advantage of Owens Threshold Tone Decay
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-several modifications -effectively ID retro path -low cost -assessible
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disadvantages of Owens Threshold Tone Decay
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-time consuming/fequ -no universal classif for results
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STAT-supra threshold adaptation test
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-Presentation level is 100dBHL at 500Hz, 105dBHL at 1000 & 100dbHL at 2000Hz -presentation time= 60 sec at each frequ -if any tone becomes inaudible, retro path suspected
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Traditional Bekesy Audiometry
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-sweep frequ tones(125-10k) 1 octave per minute -tones continuous or pulsed -attaches to x-y plotter -threshold is midpoint of excursions -comparison of pulsed & continuous threshold traces used to diff cochlear from retro
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Type 1 Bekesy
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overlapping of tracings with excursion width approx 10dB -normal or CHL -excursion width can be reduced due to better ability to detect small intensity changes as with SISI
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Type 2 Bekesy
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-at HF continuous trace falls below pulsed trace by 20dB or more -cochlear loss
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Type 3 Bekesy
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-tracings separate before reaching 1k & separation is at least 40-50dB or to equip limits -retro loss
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Type 4 Bekesy
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-tracings separate before 1kHz but not as much separation as type 3 -retro cochlear path
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Type 5 Bekesy
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-when continuous trace is better than pulsed trace -pseudohypacusis suspected
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LOT-lengthened off time Bekesy
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-more likely to yield type 5 when patient faking HL -pulsed tone is 200ms on & 800ms off -harder to match loudness of tone with continous tone
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Bekesy comfortable loudness
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-variation improves ID or retro path -patient traces comfort level instead of threshold -interpretation based on original 4 types
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Advantages of Bekesy
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-documents patients response during test -very effective in detection of cochlear pathology -several modifications
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disadvantages of Bekesy
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-$$$ of equipment/readily available -more expensive to calibrate -patients have difficult responding appropriately because of tinnitus -ID of retro involvement questioned
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PB Max
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-phonetically/phonemically balanced max -highest score on psychometric function
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PB Min/rollover
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-WRS or SRS worsens at higher intensities
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what does retrocochlear pathology cause?
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more rollover
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where is PB Max obtained?
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30-40dbSL
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verifying PB max
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-search whenever initial score is 6% continue
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when to search for PB max in standard diagnostic approach
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-search when WRS is poorer than expected & there is reasonable suspicion of retro pathology *lower limit=110.05+(PTA)(-1.24)*
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Dubno forumal for NU#6 words
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lower limit=110.05+(PTA)(-1.24)
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when is WRS for 1 ear significantly poorer than WRS for other ear?
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asymmetry suspicious for retro pathology
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when has WRS significantly changed at retest?
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change is undesirable & suspicious -Thornton & Raffins 95% confidence table
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SPRINT-speech recognition interpretation chart
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combines Dubno forumla & Thornton & Raffins table
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HA prognosis for PB max
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-not searching for PB max -test at MCL, good scores=good prognosis poor scores=poor prognosis -establish realistic expectations
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estimate of everyday speech understanding for PB max
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-presentation level for convo 50-55dBHL -not looking for PB max but for reflection of real life performance -can counteract patient denial after PB max eval leaves patient with unrealistic view of performance
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functional gain for PB max
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performance with amp can be assessed in soundfield aided vs unaided at 50-55dBHL -with/without noise, cafeteria noise, babble
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multifrequency tymp
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-sweeping prob tone from 200-2KHz -results in config tracings with multiple resembling V, W & inverted V -function of varying probe tone frequ
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shapes of multifrequency tymp
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-becomes more complex as frequ increases -inverted v single peak pressure found with LF probe tone -inverted W multi peaked appears with mid frequ -V appears with HF probe tones above resonance frequ
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significance of tracings for multifrequency tymp
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-frequ values of notching in tymp appearance -shifted towards higher frequ for ossicular fixations -frequ shifts towards lower frequ for post stapedectomy & ossicular discontinuities
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clinical application of multifrequency tymp
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-distinguish between LF & HF -looks at mass, stiffness, resistance associated with disease
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why isn't multifrequency tymp being used?
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-never embraced by audiologists -insufficient justification of results -cost of added feature to equipment -time is an issue -reimbursement not listed in CPT but can use tymp with modifier
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4 patterns of admittance tymps based on?
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number of combined minimal & max in susceptance (B) & conductance (G) tymps
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susceptance (B)
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-inverse of reactance & associated with imaginary part of admittance
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conductance (G)
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-inverse of resistance -equal to real part of admittance
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4 classifications of multi frequ tymp Van Heusen
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-1B1G -3B1G -3B3G -5B3G
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1B1G tymp
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-both B & G tymp have a single peak -lower than resonance frequ
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3B1G tymp
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G tymp single peak B has 2 max & 1 min or 3 extrema -at resonant frequ of system
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3B3G tymp
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-both B & G tymps have 3 extrema -above resonance frequ
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5B3G tymp
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-G tymp has 3 extrema -B tymp has 5 extrema -above resonance frequ
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why do we need multifrequency tymp?
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-infants <6-7 months -226Hz probe tone, insensitive to ME -higher frequ probe tones 630Hz & 1000Hz
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fistula
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-abnormal connection or passageway between 2 epithelium-lined organs or vessels -disease condition but may be surgically created for therapeutic reasons
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what is perilymphatic fistula?
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-tear or defect in 1 or both small, thin membrane between ME & IE -OW, RW separate ME from fluid filled IE -severity & complexity vary (very mild to incapacitating)
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etiology of fistula
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-perilymph leaks from perilymphatic spaces of bony labyrinth into ME space -loss of perilymph alters balance between perilymph & endolymph in membranous labyrinth -can be either unilateral or bilateral -rarely occur spontaneously
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what do you feel with fistula?
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-normal pressure changes now cause inner ear to be stimulated -balance system & hearing systems are adversely effected
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symptoms of fistula
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-HL (LF)-can range from flat to HF, fluctuating, mostly SNHL -tinnitus -aural fullness -vertigo -disequilibrium
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series of events for fistula
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-membrane rupture -rapid severe HL -loud roaring tinnitus -severe rotational vertigo: visceral symptoms=sweating, pallor, nausea, vomiting -examine nystagmus & instability -SNHL
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diagnosis of fistula
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-no consensus on frequ of occurrence -how to diagnose: valsalva maneuver(hold nose & create ear pressure) -patient reports inconsistent bc of fluctuation of symptoms -treatment=surgical exploration & operative repair needed, heal on own, bed rest, elevation of head on bed, stool softeners, avoidance of Valsalva maneuver & sedation -symptoms can be masked by more serious medical problems -elusive symptamology partially responsible for controversy surrounding disorder -often depends on antecedent otologic history: surgery, trauma, diving, congenital ear malformation -trauma frequently reported
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congenital causes of fistula
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-utero -birthing process
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acquired causes of fistula
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-head trauma -rapid changes to intracranial pressure -atmospheric, scuba diving, airplanes, weightlifting, child birth, chronic severe infections
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testing of fistulas
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-dynamic platform posturography -electrophysiology test -fistula test -imaging
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dynamic platform posturography
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-pressure applied to EAC -vestibular pattern observed -abnormal sway -anterior, posterior, lateral -platform fistula test-positive
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electrophysiology test
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-EcoG -intracochlear electrical potential changes associated with hearing -3 separate responses: alternating current potential, summating, action potential -2 methods of recording: transtympanic, extratympanic
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fistula test
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-positive pressure to TM: possibly produce nystagmus, positive fistula test -objective record of fistula testing -ENG/VNG & impedance bridge -immittance probe placed in ear -present pressure at +200daPa decreasing to -200daPa -during change in pressure recording of eye movement is conducted for presence of nystagmus
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imaging
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-MRI: gadolimium enhanced to exclude acoustic neuroma or structural lesions of cerebellar pontine angle or neuraxis -CT scan nonenhanced fine-cut CT of temporal bones in children -incidence of PLF much higher in those with congenital deformation of otic capsule -progressive or sudden loss in children with incompletely developed ear has higher risk of PLF
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treatment of fistula
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-self healing: bed rest, no heavy lifting, avoid pressure changes -surgical- graft over window
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superior canal dehiscence
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-OW & RW work together to regulate hearing & balance -mechanical wave is transduced into neural activity & sound is perceived -created by 3rd window -opening in bone overlying superior semicircular canal of ME
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symptoms of superior canal dehiscence
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-vertigo -oscillopsia -autophony -hyperacousis -CHL -evoked by loud noises and or by maneuvers that change ME or intracranial pressure- coughing, sneezing, straining
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characteristics of superior canal dehiscence
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-mean age of patient 45 yrs -unilateral -bone overlying contralateral superior canal is abnormally thin -1 of 3 bilateral but one ear has greater signs -1-2% of population have abnormally thin bone but not SCD
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tulio phenomenon
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-vestibular symptoms induced by loud sounds
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what is superior canal dehiscence associated with?
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-syphilis -perilymphatic fistula -congenital deafness -menieres disease -head trauma -lyme disease -cholesteatoma wit labyrthine fistula -fenestration operations
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testing of superior canal dehiscence
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-vestibular evoked myogenic potentials -loud tones evoke short latency relaxation potential in ipsi sternocleidomastoid muscles -patients typically have lower than normal threshold for VEMP response & amplitude waveform is greater for comparable stimulus intensities than in ear without dehiscence
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treatment of superior canal dehiscence
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-tolerate their symptoms -avoiding stimuli that make symptoms worse -surgical correction: possible side effects=possible HL
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ipsilateral pathway
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-ipsi ME, cochlea, CN VIII, ventral cochlear nucleus, SOC, facial motor nucleus, CN VII -stapedius muscle in ipsi ME
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contralateral pathway
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-ipsi ME, cochlea, CN VIII, ventral cochlear nucleus -contra SOC, facial motor nucleus, CN VII -stapedius in muscle of contra ME
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presentation frequ of ipsi & contra reflex
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500, 1k, 2kHz 4kHz not reliable BNB
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partial reflex thresholds
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-present at some frequ -absent at others
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elevated reflex thresholds
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-exceed 100dB HL -result of L depends on degree of loss
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absent reflexes
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-normal ME function -mild to moderate SNHL (60dB or worse) -suggest retrocochlear pathology, brainstem lesions -normal hearing sensitivity -ME disease -possible neurological involvement: CN VIII, auditory neuropathy, CN VII *if ME normal, suggests neural pathway lesion before stapedius muscle innervation*
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ME pathologies
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-ME fluid -disarticulation -perforation -otosclerosis
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ME fluid
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-renders stapedius muscle immobile or partially
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disarticulation
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-energy can not transfer easily through ossicular chain & reflex cannot be accurately assessed -break lateral to insertion of stapedius muscle -contraction not transmitted to TM=absent reflexes in probe ear -opposite result possible: present contra reflexes with A/B gap in probe ear
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perforation
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-resistance of TM compromised & contraction of stapedius muscle not occur properly
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otosclerosis
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-stiffening of bones results reduced muscle contraction
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contralateral reflex
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-reflex expected to be >95dBHL if loss is 45dBHL -reflex expected to be 100-115dBHL if cochlear HL is 50-70dBHL -50% patients have reflex with loss up to 80dBHL
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cochlear disorders
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-related to degree of HL -less than approx 50dBHL=generally normal thresholds, IHC intact, afferent paths sufficient to activate ASR -greater than approx 50dBHL: AR threshold elevated/absent, more severe loss more difficult to distinguish between cochlear & retro -greater than 80dBHL very unlikely to have AR, IHC extensively damaged, stimulus level not sufficiently high to evoke reflex *pattern=stimulus effect* elevated or absent depending on degree of loss
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Metz Test
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-comparison between ART & HL to determine cochlear or retro -diff of less than 60dB between ART & hearing threshold at same frequ was positive for cochlear HL with recruitment
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retrochochlear/8th nerve in regards to reflex
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-ASR typically elevated or absent with stimulus presented to affected ear
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unilateral ME pathology
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-right disordered ear= probe ear NR, abnormal function of ME, space prior to initiation of stimulus tone -non-probe ear=NR measured in disordered ear, due to abnormal ME -left normal ear= probe ear normal & no abnormality -non-probe ear=elevated response, stimulus traveling through abnormal ME space
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bilateral ME pathology
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Probe ear -ipsi=absent -contra=absent -fluid: stiffening effect does not allow for change in stiffening of muscle to be recorded when reflex is activated by stimulus
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Sensorineural loss cochlear dysfunction
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-depends on degree of loss -losses less than 50dbHL will typically have no effect on reflex pattern losses between 50-80dBHL reflexes may be elevated -losses greater than 80dBHL reflexes more than likely will be absent
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retrochochlear dysfunction
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-CN VIII (acoustic& vestib) -disordered ear ipsi=reflexes absent contra=reflexes present -normal ear ipsi=reflexes present contra: reflexes absent
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facial nerve dysfunction
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-ipsilateral absent reflexes: stapedius does not contract -contra absent reflexes: stapedius on R does not contract even with stimulation of L -normal ear= present reflexes for ipsi & contra
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acoustic reflex decay
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-continuous stimulus for 10sec -500 or 1kHz -presentation at 10dBSL between 90-105dB (do not exceed 110dBHL) -stapedius muscle contracts & able to hold contraction at max ampl in normal -stapedius contracts but within 5 sec amplitude decreases more than 1/2 max amplitude
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auditory neuropathy
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-etiology unclear -wide range of severity of HL & symptoms -OAE present, reflexes absent/elevated -abnormal acoustic reflexes at 1&2kHz -ipsi or contra -ABR waveform abnormal/absent
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facial nerve lesion identification
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-paralysis with normal stapedial reflexes=assume can be made that nerve is normal from level proximal to brainstem -paralysis with abnormal stapedial reflexes= lesion at location or distal to pyramid turn of facial nerve
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brainstem pathology
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-AR elevated/absent in retrocochlear pathologies -extra axial disorder=vestibular schwannoma, affected side elevated or absent -intra axial disorder=acoustic neuroma at level of crossing pathways, contra reflexes abnormally bilateral, ipsi reflexes normal
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pseudohypacusis/functional loss
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-abnormally low ART for hearing threshold -Tonal ARTs are on effective non behavioral tool for ID functional loss -when thresholds >60dBHL -ARTs cannot ID functional component when thresholds <55dBHL
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results of acoustic reflex decay
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-muscle holds contraction for more than 5 sec without decreasing more than 1/2 initial amplitude -normal, cochlear, CN VII or VIII -decay noted then may be tumor or bell's palsy
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7th nerve involvement
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-proximal (central) of stapedius= probe in ear on affected side= absent -distal (more peripheral)=probe in ear on affected side=present
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vestibular aqueduct
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-small bony canal -vestibule to posterior portion of petrous portion of temporal bone -contains endolymphatic duct attached to sac (fluid filled) -congenital malformation -dilation of endolymphatic duct & sac
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what are the functions of a vestibular aqueduct?
answer
-regulate ion concentration in IE -transmission of sound & balance signals from ear to brain
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Mondini
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-Italian physician -tomography -Mondini malformation=missing turn in cochlea -anatomy of cochlea
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characteristics of enlarged vestibular aqueduct syndrome
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-most common ID inner ear bony malformation in children with SNHL -no unique characteristics -early onset HL -vestibular disturbance -trauma -Pendred syndrome
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Pendred syndrome
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-autosomal recessive SNHL -Mondini dysphasia of cochlear -enlarged thyroid gland
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audiologic assessment of enlarged vestibular aqueduct syndrome
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-auditory -vestibular -depends on age of patient & ability *case history important*
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auditory assessment results of enlarged vestibular aqueduct syndrome
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-unilateral or bilateral -mild to profound -fluctuating, progressive or sudden -sloping, rising, flat, cookie bite -mixed
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vestibular assessment results of enlarged vestibular aqueduct syndrome
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-mild imbalance to episodic vertigo
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avoiding misinterpretation mismanagement of enlarged vestibular aqueduct syndrome
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-A/B gap can lead to misdiagnosis -computer tomography -MRI -CBC
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caution to patient for enlarged vestibular aqueduct syndrome
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-avoid head trauma especially on side effected
