2 - Verbal auditory agnosia
Rapin (1997) proposed that "verbal auditory
agnosia," an inability to detect syllable and word
boundaries in rapidly presented streams of speech,
might be the cause of the language disorder of some
children with autism [1]. This could also explain the
echolalic speech of children with autism: the use of
whole phrases that often seem badly out of context.
Normal children appear to extract meaning by
recognizing stressed syllables [2, 3]. Early speech
(baby talk) is based on use of these meaning-laden
syllables, which are applied correctly, if often
amusingly, to new contexts.
Magnetic resonance imaging (MRI) has since 1991
revealed damage localized in the midbrain auditory
nuclei, the inferior colliculi, in people who lost the
ability to understand speech following traumatic injury
or illness [4-11]. Authors of some of these case
reports define the loss of speech understanding as
"word deafness," the neurological term for loss of the
ability to discriminate speech sounds.
Agnosia is defined as an inability to recognize
information provided by sensory experience. A
person who loses the ability to differentiate a coin
from a key in his pocket is an example of tactile
agnosia; he may be able to feel the presence of two
objects but cannot distinguish between them without,
for example, looking at them. The agnosia is
restricted to the sense of touch.
Agnosia for markers of syllabic components would
appear to be the primary defect of the loss of speech
understanding described following injury of the
inferior colliculi in people whose language usage had
up to that point been normal. How much more
serious this condition is for a child who has not yet
learned to speak. Rapin et al. (1977) encouraged
bypassing the acoustic channel, and teaching of
language visually to children with verbal auditory
agnosia [12].
Language has been the giant step for the human
species. Language would appear to be a great
shortcut around reasoning based on a succession of
visual images. Social instincts have surely evolved to
a higher level through use of language, and provided
a survival mechanism favored by natural selection.
Language has enabled societies to remember history
and to improve upon past inventions, and is the
means for learning and passing on information from
one generation to another.
Children who learn to speak, but whose language
skills remain poor, are less able to develop full social
competence. Immigrants from foreign lands, who
have had to learn a second language, felt afraid to
attempt phone conversations, or even encounters
with strangers in public, perhaps understand best the
social disorder that afflicts children with autism.
Language competence is of utmost importance, and
needs to be the focus of special education for
children with autism.
Furthermore, so-called “non-verbal learning disability”
should be viewed as an incomplete competency for
language [13]. Use of sophisticated sounding
phrases does not imply full comprehension. Children
who are able to commit large amounts of information
to memory do not always understand what they
appear to know. Learning to paraphrase and apply
learned information to new and different situations is
essential to the education of all children.
- Rapin (1997) Autism.
- Brown & Bellugi (1964) Three
processes in the child's
acquisition of syntax.
- Brown R (1973) A First
Language: The Early Stages.
- Meyer et al (1996) Pure word
deafness after resection of a
tectal plate glioma with
preservation of wave V of
brain stem auditory evoked
potentials.
- Johkura et al (1998) Defective
auditory recognition after
small hemorrhage in the
inferior colliculi.
- Masuda 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.
- Vitte et al (2002) Midbrain
deafness with normal
brainstem auditory evoked
potentials.
- Hoistad & Hain (2003)
Central hearing loss with a
bilateral inferior colliculus
lesion.
- Kimiskidis et al (2004)
Sensorineural hearing loss
and word deafness caused
by a mesencephalic lesion:
clinicoelectrophysiologic
correlations.
- Pan et al (2004) Auditory
agnosia caused by a tectal
germinoma.
- Musiek et al (2004) Central
deafness associated with a
midbrain lesion.
- Rapin et al. (1977) Verbal
auditory agnosia in children.
- Sundheim & Voeller (2004)
Psychiatric implications of
language disorders and
learning disabilities: risks
and management.
- Rapin I (1997) Autism. New England Journal of Medicine 337:97-104.
- Brown R, Bellugi U (1964) Three processes in the child's acquisition of syntax.
- Brown R (1973) A First Language: The Early Stages. Harvard Educational Review 34:133-
151.
- 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.
- 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.
- 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.
- 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.
- Hoistad DL, Hain TC (2003) Central hearing loss with a bilateral inferior colliculus lesion.
Audiol Neurootol 2003 Mar-Apr; 8(2):111-223.
- Kimiskidis VK, Lalaki P, Papagiannopoulos S, Tsitouridis I, Tolika T, Serasli E, Kazis D,
Tsara V, Tsalighopoulos MG, Kazis A. Sensorineural hearing loss and word deafness
caused by a mesencephalic lesion: clinicoelectrophysiologic correlations. Otol Neurotol.
2004 Mar;25(2):178-82.
- Musiek FE et al (2004) Central deafness associated with a midbrain lesion. J Am Acad
Audiol 2004 feb; 15(2):133-151.
- Rapin I, Mattis S, Rowan JA, Golden GG (1977) Verbal auditory agnosia in children.
Developmental Medicine and Child Neurology 19:192-207.
- Sundheim ST, Voeller KK. Psychiatric implications of language disorders and learning
disabilities: risks and management. J Child Neurol. 2004 Oct;19(10):814-26.