Presentation on theme: "Auditory Dys-Synchrony of Infancy:"— Presentation transcript:
1Auditory Dys-Synchrony of Infancy: Best Practices for Diagnosis, Monitoring and GuidanceMarilyn Neault, Ph.D., CCC-AFebruary 19, 2004Thanks to the audiology and otolaryngology staffat Children’s Hospital Boston
2What is auditory dys-synchrony? Presence of cochlear hair cell activity- cochlear microphonic in ABR- otoacoustic emissions (may disappear)Absence of auditory nerve response- no Wave I (no compound action potential)- no ABR wavesBehavioral hearing discrepant from ABR- idiosyncratic, fluctuating responses- audiogram may range normal to profound
3a.k.a. (also known as…) Auditory neuropathy Primary auditory neuropathy (Shivashankar)Auditory dys-synchronyAuditory neuropathy “sensu stricto” (Rapin and Gravel)Peri-synaptic audiopathyPersistent outer hair cell function(Not all the same – will break down into categories as we learn more)Your entry?
4Why do children with auditory dys-synchrony drive audiologists crazy? Pure tone audiogram and ability to detect sounds in everyday life is often better than the absence of ABR would predictWord recognition ability is worse than the pure tone audiogram would predictFunctional hearing ability fluctuates and may improveExpected benefit from hearing aids rarely realized
5Possible sites of abnormality Inner hair cellsSynaptic junction between inner hair cells and auditory neuronsDendritesSpiral ganglion cellsAxonsHeterogeneous disorder with different possible sites
7Other findings in auditory dys-synchrony Absent acoustic (stapedial) reflexesOAE’s, if present, are not suppressed by contralateral stimulationPoor word recognition ability, especially in noisePoor temporal resolutionPoor low frequency discriminationLimited or no benefit from hearing aids
8Concomitant conditions Half of newborns have NICU historiesOne-third of children (80% of adults) have other neuropathiesSural nerve biopsy may show abnormal myelinizationCharcot-Marie-Tooth (hereditary sensorimotor neuropathy)Friedrich’s AtaxiaMore than one child in family may have auditory dys-synchrony with no concomitant conditions. Mutations in the otoferlin gene may be involved (Varga, J. Med Gen. 2003)
9“Auditory Dys-Synchrony of Infancy” (“ADI”) Manifestation of cochlear activity in response to sounds without evidence of neural synchrony, in infancyTerm implies neither etiology nor prognosis
10Problems with ADI #1. Some get better, some do not, no way (yet) to predict outcome#2. Newborns with auditory dys synchrony pass OAE screen
11Parent’s viewpoint “What kind of a mother would take ‘I don’t know yet if yourbaby will be able to use his hearing to understand speech’ for an answer?”Why would they screen newborns with a method that misses my baby’s problem?Nebulous diagnosis with unknown cause and unknown prognosisEncourages shoppingSome audiologists not familiar with the conditionConflicting opinions about use of hearing aids, FM amplification
12Incidence of auditory dys-synchrony? From Sininger’s literature review:3.1 / 1000 high risk infants1/10 children with congenital hearing loss
13Typical normal ABR tracings near threshold levels R clicks 20dBHLR 4000Hz 20dBHLR 2000Hz 20dBHLR 1000Hz 20dBHLL clicks 20dBHLL 4000Hz 20dBHLL 2000Hz 20dBHLL 1000Hz 20dBHL15ms20msTypical normal ABR tracings near threshold levels
14Rarefaction clicks, 90 dBHL Condensation clicks, 90 dBHL9 month old former 25 week premie, passed newborn OAE screen but parents think she has a hearing loss
16Responses to both polarities superimposed Alternating polarity (CM not observable)Rarefaction clicks, insert phone tubing pinchedto check for stimulus artifact90 dBHL click stimuli
17(Note that the cochlear microphonic does not 102 dBHL90 dBHL80 dBHL70 dBHL60 dBHL(Note that the cochlear microphonic does nothave a longer latency at lower intensities)
18Audiogram by Visual Reinforcement Audiometry with insert earphones, on the same day as the ABR.Tympanograms: normal, OAEs: absent bilaterally(though present at newborn screen).
19Challenge to audiologists: We need to test in such a way that we’ll see the auditory dys-synchrony of infancy (ADI)We need to recognize the signs of ADI when they are staring us in the face (a prolonged CM in response to clicks is not just a stimulus artifact!)We need not to overdiagnose ADICM followed by typical ABR waves is not ADI ---we all have cochlear microphonics!Recognize other reasons why a child might have OAEs but act deaf
20From an audiologist on a learning curve: “Because the ABR response did not show polarity inversion when ipsilaterally and contralaterally recorded tracings were superimposed, there is no evidence of auditory neuropathy.” (huh?)
21From another audiologist on a learning curve: (well, aren’t we all…) “A polarity-inverting cochlear microphonic response was seen on superimposed rarefaction and condensation click tracings, indicating absence of auditory neuropathy.” (huh?)
22N3 Potential in a toddler who is deaf May have vestibular originNot a cochlear microphonic; NOT dys-synchronyDoes not reverse polarityDoes have a latency-intensity function
24Stimulus artifact generated by insert earphone and recorded by ABR electrodes
251000Hz, 100dBHL, singlepolarity stimulusOverlaid ABR stimulus artifacts from 1000Hz tone bursts, recorded from joined electrodes (no head) and from a profoundly deaf infant.
26Why did we not see auditory dys-synchrony pre-1990’s? We did -- we just didn’t know itReports of patients with ABR results poorer than behavioral audiogram appeared by 1979By mid-1990’s, widespread availability of otoacoustic emissions equipment AND use of insert earphones for ABR testing (insert earphones allow observation of cochlear microphonic response in patients with absent ABR)
27How do children with auditory dys-synchrony present to the audiology clinic? Referred on newborn ABR hearing screenPassed newborn OAE hearing screen but parents suspect child is deafA few may have passed ABR screen but then developed auditory dys-synchrony, or had a false negative result on their screenToddler with delayed receptive language development seen for VRA (WE NEED TO TEST ACOUSTIC REFLEXES FOR THESE CHILDREN)Older hearing aid user with fluctuating hearing levels and limited hearing aid benefit for degree of loss
28Joint Committee on Infant Hearing Year 2000 Position Statement Acknowledges that cases of auditory dys-synchrony may be missed by accepted screening protocolsDiagnostic audiology protocol includes ways to detect auditory dys-synchronyProblem: auditory dys-synchrony cases may not reach diagnostic evaluation if screened by OAE
29What should a UNHS program do about auditory dys-synchrony? Analyze the consequences of doing automated ABR rather than either ABR or OAE for initial screening? (auditory dys-synchrony passes OAE screen at birth)Educate audiologists to look for itEducate early intervention providers:Nature of parent experienceTypical behaviors of the childrenCommunication and therapy methodsApproach toward hearing aids and cochlear implant issues
30Benefit from visual language system Audiological / Educational Management ofInfants with Auditory Dys-synchronyBenefit from visual language systemEncourage speechreading (lipreading)Some (about 50%) benefit from hearing aids;perhaps in one earBeware of hair cell damage from hearing aid amplification, at least while OAEs are presentConsider sound field FM amplificationLanguage stimulation in quiet background; acoustic highlightingMonitor behavioral audiogram and OAEs; “hearing” may improve or decline
31Try a hearing aid or not?Beware of hair cell damage if OAEs are still present. Presence of OAEs suggests normal cochlear amplifier function.If OAEs have disappeared, try testing speech perception in each ear separately at elevated intensities. If the child understands words better at a higher than conversational intensity, try a hearing aid in that ear (or ears).
32Audiological / Educational Management of Infants with Auditory Dys-synchrony, continued Let parents know that a cochlear implant may help, if hearing does not improve and hearing aids don’t helpHelp connect parents with other parents of children with the same condition
33Auditory Neuropathy Information Homepage (with links including parent listserv)
34Why might a CI help a child with auditory dys-synchrony? The child’s auditory nerve cells do not fire in tempo with incoming sounds.The cochlear implant may act as a drill sergeant for auditory nerve fibers, stimulating them to fire in synchrony and to keep tempo with incoming sounds.
35“Problem solving is an important skill in any professional, yet it can be counter-productive if applied too early in a goal-setting endeavor, especially if done for the family rather than with them.”D. Bailey
36Typical candidacy to benefit from a cochlear implant Age 12 months and up with profound bilateral hearing lossOR age 25 months and up with severe or profound hearing loss and poor ability to recognize words through hearing aids“profound” means average hearing thresholds >90dBHL at 500, 1000 and 2000Hz, unaided;“severe” means 70-90dBHL, unaided;“poor” means no more than 30% correct repetition of one-syllable word list without clues at 57dBHL, with terrific hearing aids
37Cochlear implant candidacy for a child with auditory dys-synchrony Same as “typical” candidacy EXCEPT:Allow enough time to know whether hearing will improve or even recoverPure tone hearing levels are not the determining factor; a child may show a mild-moderate loss on the audiogram but may still benefit from a cochlear implant, if the child can not learn to recognize words without lookingAssess the reason for the condition, to assess the risk that the auditory nerve is truly “patholo-gical” or may deteriorate in function over time
38Is anything different about the CI candidacy workup for a child with auditory dys-synchrony? Should have MRI of the inner ears / auditory nerve (not just a CT scan). Consider MRI of the whole brain as well.Should be evaluated by a neurologist for other peripheral neuropathiesShould monitor functional use of hearing in case ADI is resolvingShould have ABR, OAE, acoustic reflex tests repeated just prior to surgeryConsider Auditory Steady State Response (ASSR) to assist in ear determinationAs for any CI candidate, parents should accept that outcomes are variable and not always predictable.
39What do you have to lose? (by implanting a child with auditory dys-synchrony) Ability to hear in the implanted ear when not using the speech processorAbility to determine the extent to which hearing may improve or resolve on its ownAny ability the child might have had to localize the direction of a sound source
40Likelihood of auditory synchrony on one side What do you have to gain? (by implanting a child with auditory dys-synchrony)Likelihood of auditory synchrony on one sideLikelihood of stable hearingPotential to learn to recognize spoken words and sentences in quiet without lookingByproducts of better hearing: better speech and better language
41Why might someone with auditory dys-synchrony have a particularly good CI outcome? Language base in visual language system prior to CI; may not have been severely language-deprived prior to implant.Has had and will have intense therapy and vigilant attention to communication.Most have had some auditory experience prior to implant.?? May have cellular or neural elements in the cochlea in better supply than in some types of sensorineural hearing loss??
42Why might someone with auditory dys-synchrony have a particularly limited CI outcome? Cochlear implant may not succeed in driving the auditory nerve fibers to fire in synchrony.If a degenerative nerve condition is present, such as in some mitochondrial disoders, performance with the CI could decline over time.Child may have other challenges which would have made it difficult for him to learn to understand speech and to speak, even if he had had normal hearing.
43Before and after CI with auditory dys-synchrony Pure tone audiogram mild to profound, fluctuating, moderately severe most common.No nerve action potential (Wave I).No ABR response.No acoustic reflexes.AFTERSound field pure tone audiogram predictable at about 30dBHL, Hz.Nerve action potential seen on neural response telemetry.EABR response +Acoustic reflex stimulable using cochlear implant.
44Electrically evoked Auditory Brainstem Response stimulated through the cochlear implant in theoperating room
45Electrically elicited acoustic reflex stimulated by presenting a signalthrough the cochlear implant
46Models of auditory dys-synchrony Temporal bones of expired premies with outer hair cells but no inner hair cells (Amatuzzi et al., Arch. Oto. HNS 2001)Carboplatin causes selective loss of inner hair cells (but have acoustic reflexes)Mouse strain with no inner hair cellsMouse strain with early degeneration of cells that support the spiral ganglion cells
47Research questions:Need better way to differentiate which cases will improve or resolveCatalog and monitor our seriesSerial test measuresInfant auditory development scalesAdditional electrophysiological measures?Some patients have ASSR and some have cortical auditory evoked potentials, despite absence of ABR
48Research questionsCan people with auditory dys-synchrony localize sound?Does ABR or ASSR improve as pure tone audiogram and functional use of hearing improve?Is true resolution possible? (study “resolved” cases for acoustic reflexes, gap detection, discrimination in noise)Performance with cochlear implantsWhat happens to the unimplanted ear over time?
49Neault and Kenna (study in progress, 2004) Subjects: 50 children with ADI whose hearing loss was evident during the first few months of life, seen at Children’s Hospital BostonExcluded: later onset auditory dys-synchrony
50Unilateral vs. Bilateral Of 50 children with ADI as of 2/04,40 (80%) with bilateral ADI (14 of these now have cochlear implants)8 (16%) with one ear ADI, one ear normal hearing2 (4%) with one ear ADI, one ear typical sensorineural hearing loss (one now has a cochlear implant)
51How They Came to Us (N = 50) 30: Followup for newborn ABR screen referral6: Passed newborn OAE but parents suspected deafness (dx’d at months)3: Passed newborn ABR screen but suspected deaf within first few months of life (two a real pass, ? one bogus)6: Not screened; parents suspected hearing loss5: Newborn screening data not confirmed
52Characteristics of 50 Children with ADI Of 23 who had CT and/or MRI of inner ears so far, 5 showed abnormalities of cochlea or nerve (2 have normal cochlear turns, stenotic IAC, no cochlear nerve)1 has optic nerve hypoplasia9 have abnomalities on MRI of brain
53What Happened to the 50 Children So Far 14 with bilateral ADI now have cochlear implant1 with unilateral ADI, unilateral typical SNHL now has a cochlear implant6 with bilateral ADI resolved to normal hearing findings29 “other” (some still very young, some planning implantation, some developing usable but not normal hearing, all receiving habilitation, nearly all have at least somevisual language support)
54Cochlear Implant Group (the first 11 of those implanted) Preoperative hearing levels: ranged from moderately severe to profound; poorer ear implantedAge at implantation:Median 22 monthsMean 30 monthsRange 14 to 62 months
55Cochlear Implant Group (N = 11) Progress typical of children with cochlear implantsProgress commensurate with their developmental abilitiesThose who are developmentally able to demonstrate open set speech recognition have done so
56Cochlear Implant Group: What Happened to the Unimplanted Ear? One improved from very profound to severe by age 42 monthsTwo dropped from severe to profound range, one at age 2 years and one at age 4 yearsOne uses hearing aid consistently in unimplanted earOne uses hearing aid sporadically in unimplanted earNone have word recognition ability beyond pattern perception in the unimplanted ear
57Caveat Implantor Does the child have a cochlear nerve? ( One child with unilateral and one child with bilateral ADI in our series showed absence of cochlear nerves )
58Caveat ImplantorSix of 50 children with ADI in our series resolved to NORMAL behavioral and/or electrophysiological measures of hearingAll six showed signs that their hearing was improving (behaviorally or electrophysiologically) by 12 months of age, but you had to look for it
59Resolved ADI 2 sisters with no other conditions 1 boy with hyperbilirubinemia (to 44)1 boy whose mother had viral meningitis during pregnancy1 boy whose mother had Lyme diseaseand had Bell’s Palsy 4 days before delivery; baby negative for Lyme1 boy who was a 35 week premie, HIFI ventAll had maintained robust OAEs
61Sibling of girl with resolved ADI Age 3 weeks: no ABR waves, robust OAEsMother: “She acts deaf the way her sister did.”Age 3 months: Wave V present 80dB +, no reflexesAge 14 months: Normal behavioral audiogramAge 30 months: Normal audiogram, reflexes presentAU, 92% PBK score in each ear
63One month old boy with peak bilirubin 44. By five months, he had ABR waves down to30dB left and 20dB right, only at slow stim.rate. By 14 months, ABR waves down to 20dBin each ear; morphology best at slow rate.
64Resolved ADI. ABR of 17 month old boy who had no ABR RIGHTLEFTClicks 20dBHL Clicks 20dBHL4000Hz 20dBHL Hz 20dBHL2000Hz 20dBHL Hz 20dBHL1000Hz 20dBHL Hz 20dBHLResolved ADI. ABR of 17 month old boy who had no ABRwaves at birth. Still has some difficulty localizing sound.
65Same 17 month old with resolving ADI; LEFT RIGHTClicks 90dBHL Clicks 90dBHLClicks 20dBHL Clicks 20dBHLSame 17 month old with resolving ADI;cochlear microphonic remains unusually large.
66What about children whose ADI does not “resolve” but they do develop usable hearing?
6725 week premie; still no ABR waves at 2 yrs. 8 monthsSpeaks in clear 4-word sentences. Uses MicroEar BTE FMin mainstreamed preschool; comprehends speech well.
68Talker-specific understanding Localize sounds poorly Some typical things that partially hearing toddlers and preschoolers with auditory dys- synchrony doRespond to intonationTalker-specific understandingLocalize sounds poorlyDevelop articulation out of the usual order for sensorineural hearing lossVowel distortions (poor low freq discrimination)May have unvoiced plosives in their speech and be able to imitate themMay benefit inconsistently from hearing aids
69How can a child with no ABR synchrony develop “hearing?” Perhaps …“…The brain ingeniously builds an accurate clock from an enormous number of sloppy ones….”--Steven Strogatz (2003)SYNC: The Emerging Scienceof Spontaneous Order
70(Strogatz, 2003)“ ….Left to their own devices, this motley bunch of neural oscillators would fire off impulses at disparate rates, producing an electrical racket akin to the sound of an orchestra tuning up before a performance. To work together as an accurate clock, these hypothetical oscillators would need to cooperate, to sense one another’s electrical rhythms so as to stay in step.”
71Conclusions Regarding Auditory Dys-Synchrony of Infancy (ADI) Infants with ADI are not always good implant candidates2/50 had no cochlear nerve6/50 resolvedA few will develop enough usable hearing that CI surgery may not be necessaryThose who prove to be good candidates benefit greatly from cochlear implantation, in a manner typical of other deaf children with the same cognitive abilities and pre-implant language base
72Conclusions Regarding Auditory Dys-Synchrony of Infancy (ADI) Those who are going to resolve start developing ABR waves by 12 monthsBUT you have to look for it; may need to slow the stimulus repetition rateRepeat ABR and monitor functional hearing again just before early CI surgery for a child with auditory dys-synchrony
73Additional ThoughtsChildren with “resolved” ADI missed out on a few months of good hearing and should not be cut off from early interventionParents may have much invested in acceptance of hearing disorderChildren may still have subtle auditory disorders and should be watched