1. Meyer B et al. (1996) Pure
    word deafness after resection
    of a tectal plate glioma with
    preservation of wave V of
    brain stem auditory evoked
    potentials.
  2. Masuda S et al. (2000) Word
    deafness after resection of a
    pineal body tumor in the
    presence of normal wave
    latencies of the auditory brain
    stem response.
  3. Johkura K, et al. (1998)
    Defective auditory recognition
    after small hemorrhage in the
    inferior colliculi.
  4. Pan CL et al. (2004) Auditory
    agnosia caused by a tectal
    germinoma.
  5. Hu CJ et al. (1997)  Traumatic
    brainstem deafness with
    normal brainstem auditory
    evoked potentials.
  6. Vitte E, et al.(2002) Midbrain
    deafness with normal
    brainstem auditory evoked
    potentials.
  7. Coslett HB et al. (1984) Pure
    word deafness after bilateral
    primary auditory cortex
    infarcts.
  8. Denes G, Semenza C. (1975)
    Auditory modality-specific
    anomia: evidence from a
    case of pure word deafness.
  9. Cocito D et al.(1990)
    Hematoma of the inferior
    colliculus: uncommon cause
    of trochlear nerve deficit and
    contralateral sensory
    hemisyndrome.
  10. Champoux F et al. (2007).
    Auditory processing in a
    patient with a unilateral lesion
    of the inferior colliculus.
  11. Hashimoto T et al. (1995)
    Development of the
    brainstem and cerebellum in
    autistic patients.
  12. Gaffney GR et al. (1988)
    Morphological evidence for
    brainstem involvement in
    infantile autism.
  13. Abell F et al. (1999) The
    neuroanatomy of autism: a
    voxel-based whole brain
    analysis of structural scans.
  14. Aylward EH  et al. (1999) MRI
    volumes of amygdala and
    hippocampus in non-mentally
    retarded autistic adolescents
    and adults.
  15. Elia M et al. (2000) Clinical
    correlates of brain
    morphometric features of
    subjects with low-functioning
    autistic disorder.
  16. Simon EN. (2005) Auditory
    agnosia caused by a tectal
    germinoma.
5 -  Word deafness and the inferior colliculi
At least thirteen cases have been reported, of loss of
speech understanding following bilateral damage of
the inferior colliculi, all in people with previously normal
language.  The case reports are summarized in
chapter 8 above.  Inability to understand spoken
language is often referred to as "word deafness."   
Meyer et al. (1996) and Masuda et al. (2000) reported
loss of speech comprehension following accidental
destruction of the inferior colliculi during surgery for
removal of tumors [1, 2].  Johkura et al. (1998)
reported a case of traumatic injury to the inferior
colliculi suffered in a skiing accident [3].

In December 2004 Pan et al. reported auditory  
agnosia in a young boy who developed a cancerous
growth of the midbrain that involved both inferior
colliculi [4].  Removal of the abnormal tissue was
successful in this case, with slow but steady recovery
of auditory discrimination.  Pan et al. cited the cases of
Meyer et al., Masuda et al., and Johkura et al., plus
those of Hu et al. (1997) and Vitte et al. (2002) [5, 6].

The case reported by Hu et al. was the result of
traumatic injury in a motor vehicle accident [5].  Vitte et
al. reported two cases, one the result of head injury,
the other from hemorrhage following surgery [6].

Meyer et al. commented that they were aware of three
other cases of pure word deafness with lesions
restricted to the inferior colliculi, but did not give
citations to other published reports [1].  Johkura et al.
reviewed the literature on verbal auditory agnosia, first
reported with left temporal lobe damage that
disconnected the language receptive area from
subcortical auditory input and inputs across the corpus
callosum from the right temporal lobe.  Later it was
found that verbal auditory agnosia most often involved
bilateral temporal lobe damage, or disruption of the
auditory pathway from the medial geniculate bodies of
the thalamus [7, 8].  The cases of word deafness
following damage of the inferior colliculi in the 13 case
reports above, indicate that disruption even at the
midbrain level can interfere with language
comprehension.

Word deafness results only from bilateral damage of
the inferior colliculi [9, 10].  Champoux et al. (2007) did
extensive testing of a 12-year-old child with traumatic
injury of the right inferior colliculus.  The child did not
display any neurological dysfunction, but speech
comprehension was impaired in the presence of
competing sounds.

Loss of function within the inferior colliculi present from
birth might be expected to prevent acquisition of
language through the normal channel of hearing.  
Lesions of the inferior colliculi caused during a
traumatic birth might be visible in MRI scans, but might
also be overlooked when clear-cut damage to wider
areas of the brain are evident.

Impairment of function without visible damage within
the inferior colliculi probably would not be seen in MRI
scans.  However, decreased volume of brainstem
areas in individuals with autism have been determined
by measurements of MRI scans [11-15].  This evidence
supports the usefulness of considering the perinatal
vulnerability of brainstem nuclei, and impaired function
of the inferior colliculi in the developmental language
disorder of children with autism.  In their reply to my
letter on auditory agnosia
resulting from a germinoma
growth into the
tectum, Pan and Hsieh commented:

    "Previous studies on structural abnormalities in
    pervasive developmental disorders were
    hampered by inadequate anatomical resolution of
    conventional imaging tools. Functional
    disturbances without obvious anatomical changes
    are likely to be overlooked in some of these
    conditions.  With the advance of neuroimaging
    techniques, particularly the magnetic resonance
    imaging, these hypotheses are ready to be
    tested" [16, p339].
Auditory functions required to extract meaning from
spoken language should be a primary focus of
research in autism.  Results of existing diverse studies
of the auditory system may be useful although most
such research was not about autism.
Full References
top
References
Damage of the inferior colliculi (top)
that resulted in "word deafness."
 
From Johkura et al. (1998)
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  1. Meyer B, Kral T, Zentner J. (1996) Pure word deafness after resection of a tectal plate glioma
    with preservation of wave V of brain stem auditory evoked potentials. Journal of Neurology,
    Neurosurgery and Psychiatry. 61:423-4.
  2. Masuda S, Takeuchi K, Tsuruoka H, Ukai K, Sakakura Y. (2000) Word deafness after
    resection of a pineal body tumor in the presence of normal wave latencies of the auditory
    brain stem response. The Annals of otology, rhinology, and laryngology. 2000 Dec;109(12 Pt
    1):1107-12.
  3. Johkura K, Matsumoto S, Hasegawa O, Kuroiwa Y. (1998) Defective auditory recognition
    after small hemorrhage in the inferior colliculi. Journal of the Neurological Sciences. 161:91-
    6.
  4. Pan CL, Kuo MF, Hsieh ST. Auditory agnosia caused by a tectal germinoma. Neurology.
    2004 Dec 28;63(12):2387-9.
  5. Hu CJ, Chan KY, Lin TJ, Hsiao SH, Chang YM, Sung SM. (1997)  Traumatic brainstem
    deafness with normal brainstem auditory evoked potentials. Neurology 1997;48:1448–1451.
  6. Vitte E, Tankéré F, Bernat I, Zouaoui A, Lamas G, Soudant J. Midbrain deafness with normal
    brainstem auditory evoked potentials. Neurology 2002;58:970–973.
  7. Coslett HB, Brashear HR, Heilman KM. Pure word deafness after bilateral primary auditory
    cortex infarcts. Neurology 1984;34:347–52.
  8. Denes G, Semenza C. Auditory modality-specific anomia: evidence from a case of pure
    word deafness. Cortex 1975;11:401–11.
  9. Cocito D, Amedeo G, Gallo G, Vischia F, De Lucchi R. Hematoma of the inferior colliculus:
    uncommon cause of trochlear nerve deficit and contralateral sensory hemisyndrome. Ital J
    Neurol Sci. 1990 Feb;11(1):71-4.
  10. Champoux F, Paiement P, Mercier C, Lepore F, Lassonde M, Gagne JP.Auditory processing
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  11. Hashimoto T, Tayama M, Murakawa K, Yoshimoto T, Miyazaki M, Harada M, Kuroda Y (1995)
    Development of the brainstem and cerebellum in autistic patients.  Journal of Autism and
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  12. Gaffney GR, Kuperman S, Tsai LY, Minchin S (1988) Morphological evidence for brainstem
    involvement in infantile autism. Biological Psychiatry 24:578-586.
  13. Abell F, Krams M, Ashburner J, Passingham R, Friston K, Frackowiak R, Happe F, Frith C,
    Frith U. (1999) The neuroanatomy of autism: a voxel-based whole brain analysis of
    structural scans. Neuroreport. 10:1647-51
  14. Aylward EH, Minshew NJ, Goldstein G, Honeycutt NA, Augustine AM, Yates KO, Barta PE,
    Pearlson GD. (1999) MRI volumes of amygdala and hippocampus in non-mentally retarded
    autistic adolescents and adults. Neurology. 53:2145-50.
  15. Elia M, Ferri R, Musumeci SA, Panerai S, Bottitta M, Scuderi C. Clinical correlates of brain
    morphometric features of subjects with low-functioning autistic disorder. J Child Neurol.
    2000 Aug;15(8):504-8.
  16. Simon EN. Auditory agnosia caused by a tectal germinoma. Neurology. 2005 Jul 26;65(2):
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