Auditory neuropathy spectrum disorder (ANSD) is characterized by normal outer hair cell function but abnormal or absent auditory brainstem response, despite mild to profound hearing loss. A 27-year-old female presented with right-sided hearing loss, vertigo, and tinnitus for several years. Testing found normal outer hair cell function but abnormal auditory brainstem responses, consistent with progressive ANSD. Treatment options for ANSD are limited but may include hearing aids, cochlear implants, or speech therapy depending on the severity and progression of the hearing loss.
7. • IMPEDENCE –
bilateral reflexes were absent
no e/o middle ear pathology
• Speech audiometry tests-
Speech reception threshold-
right-50dB HL
left-50dB HL
Speech discrimination score –
right -30%
left -35%
8. • OAE-bilateral OHC functional
• BERA
- for all five waves peaks could not be
obtained at 90dB HL for click stimuli at a
repetition rate of 11.1 clicks per seconds
-Wave morphology & replicability was poor
• CERA
-prolonged latency and reduced amplitude
-abnormal waves
9. ….Hearing ,feeling but never truly
comprehending
• Audiologic evaluation revealed ….
• HEARING LOSS AND SPEECH
INTELLIGIBILTY SCORES OUT OF
PROPORTION TO HER PRESUMED HEARING
LOSS
Progressive ANSD
10. • Only treatment options left with us to address
her complaints were–
SPEECH ENHANCING STRATEGIES
COMMUNICATION STRATEGIES
ASSERTIVE TRAINING
As she was not ideal for a hearing aid or
implantation considering her magnitude of
hearing loss
11. AUDITORY NEUROPATHY
or AUDITORY DYSSYNCHRONY
• Describes a diagnosis with observations of
inconsistent measures of hearing, i.e. where
hearing sensitivity is better than might have
been expected from the acoustic brainstem
evoked responses
12. • Cochlear amplification is preserved in these individuals,
but discharges from the auditory nerve is asynchronous
• Synchronous firing of auditory nerve fibers is important
for extracting complex acoustic features such as spectral
peaks and waveform envelopes for speech recognition.
• The inability to follow temporal fluctuations is an
important cause for poor speech perception in
individuals with ANSD
13. …...characterised by
Normal outer hair cell function evidenced by
normal EOAE and / or cochlear microphonics
responses coupled with
absent or severely abnormal ABR responses
Pure tone audiogram may range from normal to
profound hearing loss
Elevated or absent middle ear reflexes
14. • Impaired speech discrimination scores and increased
speech reception thresholds
Rule out central auditory processing disorders
• Binaural intergration and seperation
• Monoaural low redundacy speech
• Temporal resolution measurement
gap in noise test
amplitude modulation detection test
• LLR
15. PREVALENCE
• Overall prevalence rare- 1-3 children per 10,000
births
• 40% in neonates with high risk for HL
• 2-15% in children with known hearing loss
• 1 in 10 children with hearing loss and severely
abnormal BERA
16. PREVALENCE
• Our data shows (study conducted in rgggh mmc
ISH 2010-2012) prevalence of ANSD among
sensory neural hearing impaired is not rare but
accounts for 5.06%
• Prevalence among children undergoing
screening -0.42%
17. More common in children
50 % of all cases and 92 % of all bilateral cases
manifests before 4 yrs of age
Late onset ANSD –Rare incidence
18. RISK FACTORS
• Neonatal history of
anoxia
hyperbilirubinemia
mechanical ventilation
• Congenital brain abnormalities
• Low birth weight
• Extreme Prematurity- < 28 wks
• Genetic or family history of AN/AD
• Also seen in association with Viral diseases , seizure
disorders, high grade fever
19. ETIOLOGY
• Abnormality causing AN/AD resides in the lower
auditory system- specifically
damaged inner hair cells
abnormal IHC - auditory nerve synapse
the spiral ganglion neurons
or the axons or dendrites of the auditory nerve
itself.
Reduced neuronal populations in brainstem
20. • Mutation in otoferlin-most common genetic
cause of non syndromic AN
• Otoferlin is a calcium detector for exostosis –required for replenishment of
vesicles in active regions
• Absence of functional otoferlin protein
selectively affects the inner hair cell synapse,
resulting in profound deafness with preserved
OHC function.
21. Etiology and associated conditions
• A mutation(overexpression) in DIAPH3 causes nonsyndromic dominant
AN- defect of inner hair cell stereocilia and loss of synapses results in
this phenotype
• Syndromic neuropathies–
1.Friederich ataxia(normal wave1 & middle ear auditory symptoms
reflexes,indicating brainstem anomaly and not manifests first
auditory nerve or IHC) occurs as a part of
2.charcot Marie tooth disease generalised neural
3.Lebers hereditary optic neuropathy deterioration
4.Stevens–johnson syndrome
5.Ehler danlos syndrome.
22. Etiology and associated conditions
• Aplasia or sometimes hypoplasia of the auditory
nerve with normal cochlear morphology may
also lead to an AN phenotype.
• Any neurotoxic environmental insult -including
chemotherapeutic agents, hyperbilirubinemia-
(damages brainstem cochlear nuclei, auditory nerve, superior
olivary complex, lateral lemniscus, trapezoid bodies, inferior
colliculus) or anoxia.
23. Treatment
• Hearing normal - Speech pathology
SPEECH ENHANCING STRATEGIES
COMMUNICATION STRATEGIES
ASSERTIVE TRAINING
• Hearing aid trial for language learning
• Cochlear implant when No improvement seen with HA -
- helps in improving speech comprehension and language
acquisition
-CI provided consistent neural firing and the stimulus
promotes neural survival and restore temporal activity.
-Those with good temporal residual processing and normal
LLR performed well
• Brainstem implant-when auditory nerve is aplastic or absent
24. Our statistics
COMPLAINTS PTA SRT SISI ART OAE BERA
21/f L HOH
Reduced
clarity of
speech
R Mild low
frequency SNHL
L moderate low
frequency SNHL
R-75dB
L-80 dB
R-18%
L-8%
B/L I/L
&C/L -VE
+ AbN
2
1/2
/F
Not
respondng to
loud sounds
since birth
Not done Not
done
Not
done
Not done + AbN
22/
m
R Mild low
frequency SNHL
L minimal
frequency SNHL
R-50dB
L-60 dB
R-20%
L-18%
B/L I/L
&C/L -VE
+ AbN
25. Our statistics
COMPLAINTS PTA SRT SISI ART OAE BERA
14/f B/L HOH B/L Severe
SNHL
R-90dB
L-90 dB
R-80%
L-85%
B/L I/L
&C/L -VE
+ AbN
25/
M
B/L HOH B/L Moderate
SNHL
R-85dB
L-85 dB
R-0%
L-0%
B/L I/L
&C/L -VE
+ AbN
24/
m
B/L HOH R profound
SNHL
L severe SNHL
R-70dB
L-65 dB
R-0%
L-0%
B/L I/L
&C/L -VE
+ AbN
26. • One child benefited with cochlear implant
• Majority of the remaining benefited with hearing
aid
• One pt with severe speech recognition difficulty
but with mild hearing loss managed with speech
enhancing strategies
27. • Those with good residual temporal processing
particularly amplitude modulation detection
seems to be associated with significant benefit
from hearing aids / cochlear implant
• Late onset ANSD benefits more from hearing aid
as they would have had a long period of normal
period of normal hearing
• Those with normal LLR benefitted well with
hearing aid / cochlear implants
28. • Central auditory deafness –a continuum that includes cortical
deafness ,word deafness and auditory agnosia
• BERA normal ,CERA abnormal –cortical deafness -primary
auditory cortex of brain affected bilaterally –most commonly due
to stroke-Pt aware of their deficit ,non verbal sounds
identified,defective language comprehension and repition
• BERA MLR LLR normal - Auditory agnosia –secondary and
tertiary auditory cortex of brain(R hemisphere lesion)-Pt unaware
of their deficit –inabilty to recognize non verbal sounds,preserved
ability to comprehend speech ,amusia a subtype –inablity to
percieve music
29. ..take home message
• Neonatal screening should include BERA and not just OAE especially in
high risk cases
• Always consider AN/AD as a DD for SNHL in children and adults especially
those with speech recognition difficulties
• Clearer protocols to locate site of insult in AD/AN is lacking ,,, eg : no tests
are available to asses the function of IHC
• Need protocols to describe
-stable AN/AD
-progressive AN/AD- manifests in adolescents or early childhood
-reversible AN/AD
-maturational defects
• Hearing aid or cochlear implant??