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.

1. AUDITORY NEUROPATHY SPECTRUM
DISORDER
Dr Anusree A Karun 2nd yr DLO
UIORL Madras Medical College
Chennai

2. 27 yr old female presented to our OPD with chief
complaints of
• Hard of hearing – right side *8 yrs
• Vertigo *8 yrs
• Tinnitus-right side * 5 yrs

3. O/E GPE- Normal ,,all pripheral nerves intact
–ear –external-normal
- eac ,tm- intact
Tuning fork tests
(R) (L)
Rinne - +ve +ve
Weber- lateralised to left
ABC- reduced not reduced
Vestibular funtion tests –normal
No cerebellar signs
No nystagmus
Facial nerve bilateral normal

4. • PTA-bilateral mild SNHL
• Pure tone average
• right ear -38.3dB HL
• left ear-38.3dB HL

5. Previous PTA -2015

6. PTA -2014

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??