Part 2- Central Auditory Evaluation in Private Practice: A Commentary with historical context and case observations

Editor’s note: Dr. Ivey presents an historical as well as his clinical perspective on CAPD in practice. In over 40 years of academic as well as clinical experience Dr. Ivey has seen a wide variety of patients. In this issue of Pathways we have asked him to write a brief commentary on some of his more interesting encounters in the clinic.

by Robert G. Ivey, Ph.D., CCC-A

An interesting child (6 year old, right-handed male) was seen who was having difficulty in school hearing the teacher and language area deficits.  Pure tone results showed normal hearing bilaterally.  SRTs were at 10 dBHL for both ears and word recognition was 94% for the right ear and 98% for the left ear.  CCS scores were striking with a 0% for the right ear and 70% for the left ear (normal).   FW scores were 32% for the right ear and 48% for the left ear (both below normal).  BR was 15% (also below normal).  Auditory figure-ground was evaluated using Words in Ipsilateral Competition (WIC, WIIC) as an auditory tracking task.  For this test, the monosyllabic words are presented at a +5 dB signal to competition ratio in the same ear, one ear at a time.  For this patient, the WIC scores were 10% for the right ear (well below the cut off norm of 50%) and 58% for the left ear.  All of these results were pointing to a left temporal lobe or left hemisphere lesion.  As I was talking to his mother about the results and thinking “this is a serious neurological problem and needs a neurologic consult”, she stated “could this be due to the atrophy of his left temporal lobe?”  I said “yes” as my jaw dropped to the floor.  He had a history of the flu with a long recovery (Reye’s syndrome that can cause encephalopathy) at four years of age resulting in the left temporal lobe atrophy.

It is important to understand that having central auditory deficits do not imply that a person must have learning, language or intellectual disorders.  Two examples of significant central auditory deficits on a test battery but compensated for by high intelligence include two female patients (right-handed) one having earned the Ph.D. in speech-language pathology and the other looking forward to her orals for her Ph.D. in biochemistry.  Both reported a long history of difficulty hearing in complex auditory environments such as classrooms, restaurant and parties.  The SLP also had had difficulty in the early grades using phonics to sound-out words but had no difficulty recognizing whole words once someone told her what it was.  It was curious to me why the SLP had these difficulties.  The biochemist was worried about hearing the questions in her upcoming Ph.D. orals.  Both of these patients had normal hearing sensitivity, SRTs and word recognition (100%) bilaterally.  The SLP showed scores that were below normal for both ears on all of the tests (CCS:  right=40%, left=30%; FW:  right=46%, left=54%; BR:  50%).  The biochemist showed abnormal scores for both ears for contralateral competing sentences and a slight deficit for the right ear for auditory figure-ground discrimination (CCS:  right=20%, left=10%; FW:  right=78%, left=80%; BR:  95%; WIC:  right=45%, left=54%).  Both patients had compensated (at least to some degree) for these central auditory deficits over their life time.  Additional recommendations for the biochemist were made for the orals environment:  It was recommended that her major advisor would stipulate that during the orals that only one person would speak at a time.  It was also recommended that she repeat the question that was asked in order to assure that she had heard it correctly.

The SLP (presented above) was found to have a BR deficit and as stated earlier reported difficulty sounding-out words (phonics) as a child and was taught to read using a whole-word approach.   She had an understanding of phonics and phonemic transcription as an adult; likely from her training as an SLP.  This made me wonder and speculate, if the mechanism for the resynthesis of different (two different band-pass segments) into a recognizable unit (a word) could be an interaction between the inferior and superior colliculi) as reviewed by Stitt and colleagues in 2015.  Hence, the possibility that maybe there is visual-auditory resynthesis at this level.  There are visual-auditory tasks that are similar such as speech-reading, getting tricked by a ventriloquist, and possibly the sound-symbol association (at a preconscious level) that facilitates phonics.  If the sound-symbol connection is made at the preconscious level then the two are complementary and are perceived together (auditory and visual components of the same item) at the conscious level.  This makes sounding-out phonemes efficient.  If the association is not made automatically early-on in school then the use of phonics is difficult.  Also, I remembered Dr. Willeford’s comment that many children with BR deficits exhibited visual distractibility.  Visual distractibility may occur when the movements typically associated with the auditory information does not facilitate understanding but rather competes with the information.  This makes one speculate further that speech reading does not always work, and waving hands or body posture becomes distracting rather than adding to the message.  For example, motion activity by other children in the classroom distracts from the verbal presentation by the teacher.  Perhaps for children (and adults) with this kind of profile we need to be aware of their visual environment as well as the auditory and advise teachers not to push phonics but perhaps use a whole-word approach for learning to read (as was done in this case).

The evaluation of the brainstem with ABR, auditory cortex with late (N1, P2) and P300 responses were added to the battery when I was at the University of Western Ontario. The P300 response can be used to test auditory, visual and somatosensory systems.  This late potential can be used to evaluate difficulties with auditory and visual cueing (gaining attention).  Gaining attention is quite different than maintaining attention.  A child (or adult) with cueing deficits may appear to have attention maintenance problems (often noticed with ADD, ADHD).  The P300 task (odd ball paradigm) will alert the conscious level to a change in the auditory (primarily the language hemisphere), visual (primarily the non-linguistic hemisphere) and/or somatosensory environment in 300 msec time range.  Thus, having the conscious level alerted and checking-out “what happened” and to start attending in about one-third of a second.  This is an important process.  For example, the teacher says “ahem” (a different acoustic event within the classroom noise) and the students start listening.  It appears that the P300 response can be “loaded”.  In other words, it can be programmed to detect certain events occurring in the environment.  For example, a test situation could be set up to track responses in a in a noisy environment to a target signal such as one’s name.  Visually, the P300 can be used to monitor visual scanning and tracking for incongruent visual events, which relate to such practical things as noticing spelling errors (proofreading) reversal errors, and skipping words, lines etc.  I have made use of evoked potentials, like the P300, as much as possible to discover ways that auditory and visual systems may be malfunctioning and to monitor for maturational changes.

A ten-year-old right-handed female was seen with a history of severe chicken pox.  She had definite language deficits in areas of discourse planning, linguistic concepts and reading comprehension.  She is similar to the six-year-old male presented above with damage to the left hemisphere.  She showed right-ear deficits for CCS (right 60%, left 90%), FW (right 58%, left 72%) and WIC (right 28%, left 46%).  Binaural resynthesis was normal.  Brainstem (ABR) and late responses (N1, P2) were normal bilaterally.  The P300 response was absent bilaterally.  Recommendations for the classroom were made to take advantage of the better central auditory findings for the left ear, including up front seating with the left ear toward the teacher.  The teacher was made aware of the language-area deficits when explaining concepts to this child.  Because of the P300 deficits, she likely needs to be cued (in order to get her attention) prior to instruction and to be provided compensative and accommodative techniques for difficulties with the mechanics of reading and writing (as described above). Children with this profile may be expected to have additional difficulty with reading and written work due to language area deficits that are different from and in addition to the visual cueing deficits. This, in turn, may compound their overall learning issues.

It has been my experience, that given the proper evaluation and identifying specific deficits, appropriate recommendations can be made for preferential seating, listening devices, cueing and those for reading and written work issues that are associated with visual cueing deficits.  Special education teachers appreciate the added information that the central auditory evaluation can provide to their understanding of how a particular child functions in a learning environment.  Classroom teachers (once they implement the recommendations, and find out that they actually work) discover that this child learns just as well as the others and is not a behavioral problem after all.  The longer children remain unidentified the more likely that they will get turned-off to school and possibly drop out resulting in greater difficulties in later life.

 

About Pathways

Pathways is both a column that covers topics related to CAPD and Neuroaudiology and a society for people interested in central auditory disorders that regularly meets to discuss these issues.

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