Differentiating Auditory Processing Disorders from Auditory Neuropathy Spectrum Disorders in the Deaf-Blind Population

1
Differentiating Auditory Processing Disorders
from Auditory Neuropathy Spectrum Disorders in
the Deaf-Blind Population

• Charles I. Berlin Ph.D.
• Clinical Professor of Otolaryngology Head and
  Neck Surgery and CSD at University of South
  Florida, and Clinical Coordinator All Children's
  Hospital Center for Auditory Neuropathy

2
What does it sound like to have

• Peripheral Hearing loss vs. Auditory Neuropathy
  vs. CAPD
• Digression into underlying auditory physiology
  beginning with some of the relationships of
  speech to hearing.
• Demonstrations and videos.

3
Auditory Neuropathy Spectrum Disorders vs. CAPD

• Very easy to differentiate with the use of
  tympanometry, middle ear muscle reflexes,
  otoacoustic emissions and, if needed, an Auditory
  Brainstem Response.

4
How do we test for them

• Peripheral hearing loss, stemming from damage to
  the outer hair cells and cochlea.
• (Central) Auditory Processing Disorders
• Auditory neuropathy spectrum disorders
• Tympanometry
• Middle Ear Muscle Reflexes
• Otoacoustic Emissions
• Auditory Brainstem response

5
Tympanometry Alone
http//vimeo.com/ncdb/tympanometry-alone
Copy the above URL into your browser view
video.You must be connected to the Internet to
view the video.
6
Tympanometry (3x) and Middle Ear Muscle Reflexes
http//vimeo.com/ncdb/tympanometry-reflexes
Copy the above URL into your browser view
video.You must be connected to the Internet to
view the video.
7
Otoacoustic Emissions by Distortion Products
http//vimeo.com/ncdb/otoacoustic-emissions
Copy the above URL into your browser view
video.You must be connected to the Internet to
view the video.
8
Auditory Brainstem Response with clicks being
presented rapidly to the ear.
http//vimeo.com/ncdb/abr-to-clicks
Copy the above URL into your browser view
video.You must be connected to the Internet to
view the video.
9
Behavioral Observation by localization
http//vimeo.com/ncdb/behavorial-audiometry
Copy the above URL into your browser view
video.You must be connected to the Internet to
view the video.
10
Auditory Processing Disorders

• Thierry Morlet, Ph.D.

11
Auditory Processing

• How our brain processes the sounds we hear
• Central auditory processing includes auditory
  mechanisms that underlie the following abilities
• Sound localization/lateralization
• Auditory discrimination
• Auditory pattern recognition
• Temporal aspects of audition
• Auditory performance with competing signals
• Auditory performance with degraded acoustic signal

12
Auditory Processing and Language

• The development of language is dependent on the
  identification of sounds (including assessment of
  factors such as intensity, frequency and timing).
  This capacity enables the detection of phonemes
  and is the basis of auditory language reception
  and utilization.
• Production of a sound mirrors the perception
  individuals have of the sound.
• Central auditory processing manifests differently
  in every individual child.

13
Auditory Processing Disorders

• In children, auditory processing disorder (APD)
  presents as difficulty processing speech despite
  audiometrically normal hearing.
• Commonly, this difficulty is most pronounced in
  the presence of competing background noise,
  which, unfortunately, represents most typical
  real-world listening situations.
• The causes of APD are not known, and in all
  likelihood, APD as broadly defined represents a
  family of auditory processing deficits stemming
  from multiple causes.

14
Auditory Processing Disorders

• Approximately 5 of school-aged children have
  some type of APD.
• APD can impair a childs speech and language
  development, leading to listening and learning
  deficits.
• Its diagnosis is complex and often is not made
  until learning deficits are well established
  impairing the childs development for several
  years.
• The lack of knowledge regarding the etiology of
  APD makes its management unpredictable.

15
Auditory Processes that are affected

• Awareness/ detection
• Discrimination
• Recognition
• Figure Ground
• Synthesis

• Memory and sequential memory
• Temporal resolution
• Closure
• Binaural separation/ integration
• Attention

• Auditory processing disorders are difficult to
  differentially diagnose apart from other learning
  disorders

16
Indicators of APD Disorders

• Poor reading spelling
• Low class participation
• Withdrawn
• Responds inappropriately
• Poor receptive/expressive language
• Difficulty understanding in poor acoustical
  settings
• Attention problems

17
Risk Factors for APD

• Neurologic dysfunction and disorders, e.g.,
• neonatal risk factors (e.g., asphyxia, CMV)
• head injury
• seizure disorders
• Chronic otitis media in preschool years
• Academic underachievement or failure
• Family history of academic underachievement
• Co-existing disorder (s)

18
Co-existing Disorders The Same Brain

• APDs
• Specific language impairment (SLI)
• Learning disabilities (LDs)
• Reading disorders (dyslexia)
• AD/HD
• Emotional psychological disorders
• Developmental delay
• Other neurologic deficits
• and Autism spectrum disorders

19
Neurologic Bases
20
APD

• Understanding the source of a communication
  problem
• Peripheral or central or both?
• Physiologic versus behavioral methods
• Application of cortical auditory evoked
  potentials
• Documenting effect of training
• Neural plasticity
• Importance of tests battery and cross-check

21
Diagnosis of APD

• Ideal minimal test battery
• Electrophysiological measures
• Immittance measures Tympanometry AND acoustic
  reflexes
• Otoacoustic Emissions
• Auditory evoked potentials
• Behavioral measures
• Pure tone speech audiometry in quiet and in
  noise
• Assessing all of the individual processes of CAP

22
Auditory Physiologic Responses

• Middle ear muscle reflexes
• Otoacoustic Emissions (OAE)
• Suppression of OAEs
• Auditory Brainstem Response (ABR)
• Eight nerve and brainstem
• Middle Latency Response
• Thalamo-cortical pathways
• Cortical Responses
• N1-P2 or vertex response
• P300 response
• Mistmatch negativity (MMN)

23
Auditory Neuropathy Spectrum Disorder or APD?

• Auditory Neuropathy/Dys-Synchrony
• Synchrony disorder, possible pre-neural site
• Cochlear implants a management option
• ABR, MEMR absent
• Central APD
• More diffuse in nature, peripheral synchrony
  usually within normal limit
• Cochlear implant not useful
• ABR, MEMR usually normal

24
APD and the Peripheral Auditory System

• One possible cause of APD that has received
  attention recently is a disruption of processes
  in the peripheral auditory system this led to
  the reclassification of central auditory
  processing disorder as APD.
• Studies of peripheral auditory afferent pathways
  using click auditory brainstem responses in
  children with APD have been inconclusive.
• ABRs are present in children with APD.
• However, recent measures of speech auditory
  brainstem response show that the response in
  children with APD is delayed and less precisely
  timed, suggesting that their difficulties in
  higher-level language processes may have roots in
  the basic representation of sound as low as the
  brainstem.

25
Middle Latency Responses

• The middle latency responses arises from the
  upper brainstem and primary auditory projection
  areas.
• MLR latencies decrease with age in normal
  children.
• Changes can be seen well into childhood, and
  adult characteristics are not reached until 10-12
  years of age.
• Longer MLR latencies in children with APD.

26
Auditory Evoked Related Potentials

• AERPs provide an objective means of evaluating
  how the auditory cortex codes acoustico-phonetic
  cues crucial to speech and language processing
  with high temporal precision, including in
  presence of background noise.
• AEPRs also inform about hemispheric
  lateralization.
• Can be obtained regardless of whether the subject
  is attending to the stimuli or not which excludes
  the factor attention as a possible confounding
  factor (MMN).
• The obligatory AERP consist of a series of vertex
  positive and negative peaks (P1, N1, P2 and N2).
• Mature by mid teens
• Can be recorded at younger ages
• Neural Plasticity

From Wunderlich and Cone-Wesson, 2006
27
Asymmetries of the Auditory System

• In normally hearing individuals, anatomical and
  functional observations from the cochlea up to
  the cortex are in favor of a right ear advantage
  (REA), a feature hypothetically linked to the
  fact that in almost all right handed and most
  left handed people, speech is processed
  predominantly in the left cerebral hemisphere.
• Both afferent and efferent auditory pathways show
  asymmetrical features which suggests that
  competing signals from both ears are processed
  with a REA which enables the left hemisphere to
  process speech appropriately in difficult
  listening situations.
• Stimuli with complex speech-like acoustic
  properties, including rapid spectrotemporal
  changes, yield greater activation in auditory
  cortex over the left hemisphere, regardless of
  whether right ear, left ear, or binaural
  stimulation is used.
• The left hemisphere is specialized from birth for
  processing specific properties of speech and
  children exhibit the right ear advantage as early
  as the first year of life.

28
Asymmetries in children with APD

• Evidence of abnormalities in the cortical
  development of auditory areas in children with
  APD
• Abnormal asymmetries in the perisylvian region of
  the temporal lobe with an absence of left
  hemispheric advantage for this region.
• Abnormalities in auditory hemispheric
  specialization, in right ear advantage and in
  AERP have been reported in children with APD.
• Abnormal functioning of the left temporal cortex
  in some children with APD suggest that the
  functional specialization of both hemispheres is
  impaired in these children and that damage to the
  left hemisphere disrupts mechanisms critical for
  processing brief, rapidly changing acoustic cues.
• Enlarged AERP response in the right hemisphere
  could indicate differences in hemispheric
  lateralization in that children with APD may rely
  more on right hemisphere function when processing
  language, which has been suggested to serve as a
  compensation for improper functioning of the left
  hemisphere language areas.

29
P300

• Dependent on focusing of attention and subtle
  cognitive processes
• Can use speech stimuli of various types
  (discrimination, semantic distinctions, etc)
• Can probe psychophysical function (discrimination
  of two tones, etc)
• P300 is present in children with APDs but with
  longer latencies and reduced amplitudes as
  compared to controls.

30
Mismatch Negativity

• Neuronal response to minimal changes in acoustic
  stimuli
• Objective
• Passively elicited
• Pitch, phonemes, temporal and spectral cues, etc
• Diminished mismatch negativity (MMN) responses to
  rapidly changing stimuli in APD compared to
  normal children.

31
Efferent Auditory Pathways
32
Efferent Auditory Pathways

• The medial olivocochlear system (MOCS) innervates
  the outer hair cells. This implies that the
  acoustic signal stimulating the cochlea can be
  modified before it reaches the brain.
• The MOCS constitutes one of the physiological
  mechanisms underlying perceptual intensity
  discrimination in noise.
• In normally hearing adults and children,
  activation of the MOCS improves speech-in-noise
  intelligibility.
• The MOCS is active after term birth in humans.
  Its development is asymmetrical (in favor of the
  RE).

33
MOCS in Children with APD

• Recent studies showed some evidence of an
  impairment of MOCS function in children with APD
  or language impairment with a decrease in TEOAE
  suppression despite normal hearing thresholds.
• MOCS dysfunction has been shown in subjects with
  other deficits such as in autistic children and
  children with selective mutism.
• Several studies showed an inverted pattern of
  MOCS asymmetry in children with specific language
  impairment and in children with selective mutism
  versus controls.
• Auditory training can change MOCS asymmetry in
  children with specific language impairment
  leading to bigger suppression in the right ear
  than the left ear after training. This finding
  was observed as well in children with reading
  disabilities following audiovisual training.

34
Efferent Suppression in Normal Children
35
Suppression in Children with APD
36
Management of APD

• Requires interdisciplinary approach
• Should
• Be extensive
• Maximize opportunities for generalization
• Reduce functional deficits
• Include salient reinforcement to induce learning
• Comprehensive intervention management should
  include
• Direct skill remediation by SLP
• Compensatory strategies by Aud
• Environmental changes by teachers and/or parents

37
Intensive Computer-Based Programs for
Development of Auditory Processing Skills

• Cognitive Concepts
• Earobics
• cogcon.com
• Scientific Learning
• FastForword (FFW)
• scilearning.com
• Lindamood Bell Learning Processes
• LIPPS and Seeing Stars
• Lindamoodbell.com

38
Intervention
39
Language Skills Pre andPost Fast Forword
40
Efferent Suppression Pre-FFW
41
Efferent Suppression Post-FFW
42
MLRs Pre and Post FFW
43
MLRs Pre and Post FFW
44
Conclusions

• Like children with ANSD, children with APD have
  the basic difficulty of understanding any speech
  signal presented under less than optimal
  conditions.
• We are still not sure what causes APD. Diagnosis
  is complicated and usually not realized in a
  timely fashion. Management of APD is difficult
  and success is not guaranteed.
• Despite sharing many common outcomes with ANSD,
  APD can easily be distinguished from ANSD.