1. Sadegh jafarzadeh Ph.D Mashhad university of medical sciences
Auditory neuropathy
Sadegh jafarzadeh Ph.D
Mashhad university of medical sciences

2. Auditory neuropathy?
ABR (absent)
OAE (present)

3. ABR (absent) + OAE (present) =
Nerve dysfunction without cochlear (OHCs) dysfunction
Auditory dys-synchrony

4. Auditory dys-synchrony
Auditory neuropathy
Neural Developmental delay
Acoustic tumor (20%)
Some cases of Multiple sclerosis
Brainstem impairments (without damage to cochlea)
Truma
Blood supply
Tumors
Some syndromes

5. 10% of cases of no response ABR are Auditory neuropathy
10% of children with profound hearing loss have Cochlear microphonic

6. ABR (absent) + OAE (absent) =
Conductive hearing loss
Cochlear hearing loss
Mixed hearing loss
Nerve dysfunction with or without original cochlear (OHCs) dysfunction

7. ABR (absent) + OAE (absent)
Auditory neuropathy (30%)
Developmental delay (neural / cochlear)
Acoustic tumor
Truma

8. Auditory neuropathy ABR (absent) + OAE (absent) Autosomal Recessive
Profound HL
Otits media
CM (present)

9. Cochlear Microphonic Present at moderate to high intensity
Last for few millisecond in no response ABR
Present at moderate to high intensity
wave I cause decrease CM amplitude

10. Cochlear Microphonic or wave I
Change Polarity (reverse)
Decrease intensity (latency)
Ipsilateral noise (latency)
No sound presentation (artifact)
1 ms latency

11. Difference? Neural Developmental delay Auditory neuropathy?
Disease or delay
Wave I
Improvement (up to 2 years)
age

12. Risk factors Neural Developmental delay Auditory neuropathy
Immaturity at birth time
Truma
Neurologic risk factors
Auditory neuropathy
Hyperbilirobineama
Asphyxia
Blood change

13. Description of Auditory neuropathy (a disease)
Starr, piction, sininger, Hood & Berlin (1996)
PTA
SDS
ABR CM
OAE

14. Chief compliant:
Speech perception specially in noise
Cause:
Time processing deficit due dys-synchrony

15. Intensity discrimination
Normal
Frequency discrimination
Low frequency: Normal
High frequency: Abnormal

16. Difference?
Multiple sclerosis
Auditory neuropathy

17. Site of lesion

18. Sites IHCs Synapses & neurotransmitter Dendrite Myelin Axon
Spiral ganglion

19. Etiology Genetic (40%) Metabolic Infection Autoimmune degenerative
Idiopathic (40%)

20. Genetic
Autosomal dominant
Autosomal Recessive
Chromosome (8)

21. Autosomal dominant IHCs & Endocochlear potential
Charcot – marie – tooth
Speech perception in noise

22. Autosomal Recessive Profound HL
OAE (absent) without Middle Ear disorders
Without peripheral neuropathy(HSMN)

23. Auditory Neuropathy Age Sex Side
Progressive fluctuating or stable Hearing loss
Vestibular Neuropathy

24. Difference in cases Onset Other Peripheral neuropathy Changes in time
Related disorders
( Charcot-marie-tooth, Freiderich's ataxia, Hereditary Sensory Motor Neuropathy, Mohr-tranebjarg syndrome & gait ataxia )

25. Auditory Neuropathy without Peripheral Neuropathy
Febrile disease
ABR(I)

26. Diagnosis Neurologic: (biopsy, conduction of nerve, ankle jerk)
( MRI & CT scan are normal)
Audiologic
(PTA, SDS, Acoustic Reflex, CM, OAE, ABR, ASSR, cortical responses and Central auditory processing tests)

27. Combination of ABR & OAE cannot evaluate Auditory neuropathy

28. Audiologic Diagnosis PTA SDS Acoustic Reflex Cochlear Microphonic OAE
Suppression of OAE
Central tests for temporal processing
ABR
ASSR

29. PTA Mild to moderate HL Bilateral, symmetric or unsymmetric Range
normal hearing to profound HL

30. Speech perception Speech perception: 30-50 ms
Decreased in silent and noise
Good in early stage specially in silent
Open set speech identification score (poor)
Related to low frequency
Failure in Supra threshold temporal distortion
Speech perception: ms
Auditory neuropathy: 100ms

31. Acoustic Reflex Absent (or elevated in high level stimuli)
Afferent ( normal Non acoustic reflex)
Crossed olivocochlear reflex
Brain stem reflex

32. Cochlear Microphonic
Amplitude & Age
(Normal & AN)

33. OAE
Present or Absent?
Amplitude & Age
loss
TEOAE & CM

34. Suppression of OAE Absent in
Ipsi, contra & bilateral presentation of noise

35. ABR Absent (74%) Wave V without I (26%) Wave I Amplitude decreased
Latency increased

36. ASSR
No response
elevated response

37. Cortical responses
P1-N1
P2-N2
Elevated response

38. Mismatch Negativity Normal amplitude & latency (-5/14)
Not behaviorally discrimination
Not related to speech perception
Not related to TMTF & Gap detection

39. Central tests for temporal processing
Gap detection threshold
Temporal modulation transfer function (TMTF)
Related with speech perception