Otology Seminar--Auditory neuropathy
R3 陳俊男
95/08/08
1. History:
Davis and Hirsh (1979), Worthington and Peters (1980), Lenhardt (1981),
Hildesheimer et al (1985): paradoxical absence of ABR and only a slight
impairment of hearing but in whom cochlear microphonic or OAE had not been
recorded.
Incidence:
Davis and Hirsh (1979): 1/200 (0.5%)
Kraus et al (1984): 1.8%
Hildesheimer et al (1985): 1.9%
Berlin et al (2001): 10% of diagnosed deaf
patient
Until 2001, 70 case reports were listed as
table 1.
Symptoms:
Difficulty understanding speech, particularly in the presence of noise
Normal or near-normal hearing sensitivity but with reduced auditory perceptual or
speech processing skills
Synonym:
Auditory neuropathy (AN), auditory dyssynchrony (AD)
Etiology:
1. Genetic: mutations in several genes (MPZ, NDRG1, and PMP22) critical for
periphaeral nerve myelination and axonal survival (Chapon et al. 1999; De
2.
3.
4.
5.
Jonghe et al. 19999; Kalaydjieva et al. 2000; Maier et al. 2003)
Infectious (measles, mumps)
Metabolic (diabetes, hypoxia)
Congenital (atresia)
Neoplastic (tumors)
2. Diagnostic criteria:
Starr (1996): A group of patients with hearing deficits who had preserved OAE
and severely abnormal ABR…, complained of difficulty understanding speech,
particularly in the presence of noise…
1. Understanding of speech worse than predicted from the degree of hearing
loss on their behavioral
audiograms
2. Recordable otoacoustic
emissions and/or cochlear
microphonic,
3. Absent or atypical auditory
brain stem response
4. Hearing loss of variable
severity and configuration
Primary auditory neuropathy
(13): auditory dysfunction without no concomitant neurological deficit on a detailed
examination.
Familial auditory neuropathy (3): Nonsyndromic heterditary AN, X-linked
recessive and autosomal recessive hereditary pattern
Associated with peripheral neurologic lesions: up to 80%
Adult
Friedreich’s cerebellar ataxia: genetic disorder characterised by a progressive
degeneration of the spino-cerebellar system due to an abnormality of a gene on
chromosome 9 (called Frataxin).
Charcot-Marie-Tooth disease: hereditary motor and sensory neuropathy (HMSN) or
peroneal muscular atrophy, comprises a group of disorders caused by mutations in genes
that affect the normal function of the peripheral nerves. Type 1,
which affects the
myelin sheath Type 2, which affects the nerve fibers (also called axons)
themselves
Neonatal
Hyperbilirubinemia
3. Auditory pathway:
 Inner hair cell  Type I spiral ganglia cells  cochlear nucleus (ponto-medullary
junction)  Most, contralateral superior olivary nucleus (upper pons)  Inferior
colliculus (midbrain)  Medial geniculate ganglia (thalamus)  Cortex
(temporal lobe)
 Superior olive  (efferent olivo-cochlear bundle, OCB)  Outer hair cells of
both cochleas, larger contralateral than ipsilateral projection (Suppress OHCs
activity)
 Spiral ganglion  ipsilateral and contra-lateral facial nuclei  stapedius muscle
(middle ear muscle reflex, MEMR)
 Tactile MEMR: tensor tympani response, via trigeminal nerve
4. Specific locations of dysfunction:
5. Mechanism of “Neuropathy”
1. Demyelinating neuropathies
Hallmark: slowed or blocked nerve conduction produces motor or sensory (or
both) symptoms distal to the site of demyelination
1. Segmental (localized) demyelination: ex. Nerve compression (acoustic
neuroma)
2. Autoimmune: ex. Guillain-Barre syndrome)
2. Axonal neuropathies
Hallmark: dying back of the most distal portion of peripheral nerves because
of inadequate axonal transport, in one or both directions, of subcellular
organelles and critical metabolic substrates and growth factors between the
neuronal cell body and distal portion of its axon
3. Mixed neuropathies
6. Perceptual consequences of disrupted of disrupted auditory nerve
activity
Character of AN:
1. No significant difficulty in performing pure-tone intensity discrimination
2. Impairment in pitch discrimination at low frequencies (<4000 Hz) but not at
high frequencies (>4000 Hz)
3. Temporal processing
a.
b.
c.
d.
Difficulty detecting short sounds but not long sounds
Difficulty in gap detection even at comfortable loudness levels
Difficulty in detecting both slow and fast temporal modulations
Cannot effectively separate sounds occurring successively
e.
f.
g.
h.
Difficulty in detecting signals in noise
Can use the interaural level difference cue to localize sound
Cannot use the interaural time difference cue to localize sound
Can follow slow temporal fluctuation (3 Hz) to perceive monaural beats
but cannot follow fast fluctuation (500 and 503 Hz) to perceive binaural
beats
4. Possible models of AN
7. Management:
1. Audiologic (incorporation of screening
ABR) and medical monitoring of infants
considered to be at risk for “auditory
neuropathy”—intensive neonatal care,
family history of hearing loss, hyperbilirubinemia
2. Spontaneous recovery or no obvious symptoms of an absent ABR
 7-10% of the AN/AD patients we have seen have had no observable
symptoms other than an absent ABR, or have developed normal speech and
language with only complaints of mild difficulty in language learning or poor
hearing in noise.
 Not to manage the child as deaf until those tests show absent emissions of
absent reflexes
3. Amplification
Patient with AN have cochlear functionHearing aids are not recommended
Powerful hearing aids may destroy outer hair cell function and preventable
high frequency sensory loss
4. FM system in classroom
5. Sign language: ex. American Sign Language (ASL)
6. Cochlear implantation: All children with hearing loss in the
severe-to-profound range who do not benefit from conventional amplification
can be considered candidates for a CI
Other indication: OAEs, CM and ABR are absent and electrical stimulation
of the promontory elicits a CAP (Spiral ganglion cells are alive)
Pre-CI
Post-CI
Comparison post-CT benefit between AN and cochlear hearing loss:
1. Ling Six Sounds Test (Ling, 1978): Assess patient’s ability to either detect or
discriminate the phonemes/a, u, I, s, sh, m/ when presented auditory only (i.e., no
visual cues)  # correct/30
2. Early Speech Perception (ESP) test (Moog and Geers, 1990): Assess speech
perception ability 1=no pattern perception, 2=pattern perception, 3=some word
identification, 4=consistent word identification
3. Test of Auditory Comprehension (TAC) (Trammell and Owens, 1977):
suprasegmental discrimination, memory-sequencing abilities for up to four critical
elements, auditory comprehension, and auditory figure-ground abilities
.
8. Further study:
1. Definite pathological site of AN
2. More sensitive screening protocol for neonatal babies, especially high risk
3. Vestibular neuropathy?
4. Effective treatment? Cochlear implantation?
9. Reference:
1. Starr A, Picton TW, Sininger Y, Hood LJ, Berlin CI., Auditory neuropathy. Brain. 1996
Jun;119 ( Pt 3):741-53.
2. Berlin CI, Morlet T, Hood LJ., Auditory neuropathy/dyssynchrony: its diagnosis and
management. Pediatr Clin North Am. 2003 Apr;50(2):331-40, vii-viii.
3. Wang Q, Gu R, Han D, Yang W. Familial auditory neuropathy. Laryngoscope. 2003
Sep;113(9):1623-9.
"Auditory neuropathy": physiologic and pathologic evidence
calls for more diagnostic specificity. Int J Pediatr Otorhinolaryngol. 2003 Jul;67(7):707-28.
4. Rapin I, Gravel J.
Review.
5. Katada A, Nonaka S, Harabuchi Y.
Cochlear implantation in an adult patient with
auditory neuropathy. Eur Arch Otorhinolaryngol. 2005 Jun;262(6):449-52. Epub 2004 Nov 12.
6. Loundon N, Marcolla A, Roux I, Rouillon I, Denoyelle F, Feldmann D, Marlin S, Garabedian
EN. Auditory neuropathy or
endocochlear hearing loss? Otol Neurotol. 2005
Jul;26(4):748-54.
7. Zeng FG, Kong YY, Michalewski HJ, Starr A.
Perceptual consequences of disrupted
auditory nerve activity. J Neurophysiol. 2005 Jun;93(6):3050-63. Epub 2004 Dec 22.
8. Berlin CI, Hood L, Morlet T, Rose K, Brashears S. Auditory neuropathy/dys-synchrony:
diagnosis and management. Ment Retard Dev Disabil Res Rev. 2003;9(4):225-31.
9. Mason JC, De Michele A, Stevens C, Ruth RA, Hashisaki GT. Cochlear implantation in
patients with auditory neuropathy of varied etiologies. Laryngoscope. 2003
Jan;113(1):45-9.
10. Sheykholeslami K, Schmerber S, Habiby Kermany M, Kaga K. Sacculo-collic
pathway
dysfunction accompanying auditory neuropathy. Acta Otolaryngol. 2005
Jul;125(7):786-91.
11. Trautwein PG, Sininger YS, Nelson R.
Cochlear implantation of auditory neuropathy.
J Am Acad Audiol. 2000 Jun;11(6):309-15.
12. Starr A, Sininger Y, Nguyen T, Michalewski HJ, Oba S, Abdala C. Cochlear
receptor
(microphonic and summating potentials, otoacoustic emissions) and auditory
pathway (auditory brain stem potentials) activity in auditory neuropathy. Ear Hear.
2001 Apr;22(2):91-9.
13. Shivashankar N, Satishchandra P, Shashikala HR, Gore M.
Primary auditory neuropathy
- an enigma. Acta Neurol Scand. 2003 Aug;108(2):130-5.
14. Brown DK, Dort JC. Auditory neuropathy: when test results conflict. J Otolaryngol.
2001 Feb;30(1):46-51.