Assessing and Managing
By Marc Iskowitz
A COMBINATION OF BETTER ASSESSMENT TOOLS, more effective remediation options, and a realization that there are more children with central auditory processing disorders (CAPD) than was previously thought are contributing to a growing understanding of the condition, said James W. Hall III, PhD, FAAA.
Thanks to emerging research that may have confirmed a neurological substrate to CAPD, "we finally are beginning to comprehend CAPD from a behavioral and neurophysiologic point of view," said Dr. Hall, who will be leaving his current position as director of audiology at Vanderbilt University in Nashville, TN, this fall and joining the University of Florida in Gainesville as professor of audiology in the Department of Communicative Disorders.
Functional magnetic resonance imaging (fMRI) helps delineate which parts of the brain in children and adults become active during central or other types of auditory tasks, according to Frank E. Musiek, PhD, CCC-A, professor of otolaryngology and neurology at Dartmouth Medical School and director of the Dartmouth-Hitchock Medical Center, both in Lebanon, NH.
The imaging technique also may serve as a measurement index for how the brain is changing with training.
Currently, he and his colleagues are testing the modality to determine the areas of the brain that are involved in auditory pattern perception, a common clinical test for CAPD.
Both the American Academy of Audiology (AAA) and the American Speech-Language-Hearing Association (ASHA) have given guidance to professionals on CAPD through position statements and conference presentations.
"This has legitimized the disorder in the minds of many," Dr. Hall noted.
The CAPD population is heterogeneous, varying from mild to severe involvement. The primary diagnosis for many patients is often attention deficit hyperactivity disorder (ADHD) or dyslexia observed in school, with a secondary diagnosis of CAPD.
"These children often fall through the cracks," stated Dorothy Kelly, DA, CCC-SLP, associate professor and chair of the Department of Speech Communication at St. Joseph's College, in Patchogue, NY. "We may look at all their behaviors in terms of learning disability and may miss those subtle signs of CAPD."
Because they experience academic failure on a daily basis, these children typically feel "burned out" by the fourth grade, she observed. "A child who enthusiastically gets on the bus in kindergarten, anxious to learn, may turn into a child who hates school."
Audiologists and speech-language pathologists are defining CAPD in slightly different ways, using different tests and terminology to describe the same children.
However, "this is one patient population that requires combined, coordinated efforts of both the speech-language pathologist and the audiologist," Dr. Hall said. "It bridges that gap."
A number of electrophysiologic options have emerged for clinicians who want to select central tests with the best sensitivity and specificity, including middle latency evoked response (MLR).
Dr. Musiek has evaluated the clinical usefulness of MLR for detecting CAPD. In a study of adults ages 16-64 with confirmed central auditory system lesions, he and others found that contralateral amplitude measures were superior to latency measures in providing the best sensitivity and specificity.1
When designing a CAPD test battery, Dr. Musiek recommends combining an eletrophysiologic measure, such as the MLR, with behavioral measures of temporal processing, dichotic listening and auditory closure.
"Audiologists need to routinely think about the entire auditory system, including the central auditory system, whenever they encounter a child with hearing problems," said Dr. Hall, who has seen about a thousand children, ages 7-15, with CAPD. "A normal audiogram does not imply normal hearing. These problems can be just as devastating to a child as a peripheral hearing loss."
The speech-language pathologist is interested in language and language-dependent behaviors and the effects of central auditory nervous system dysfunction on academics, explained Dr. Kelly.
In her CAPD assessment there are 10 to 15 different tools, depending on the case. To explain reading, writing, spelling and phonology problems, she looks at the relationship of test results for central auditory processing and language, as well as anecdotal and informal reports from the teacher, parents, school psychologist, school nurse, audiologist and child.
"It's an assessment puzzle in terms of explaining the relationship of all those findings from various disciplines," she said. "I don't advocate the use of any specific tools as long as all areas are assessed; there are many paths to heaven."
When examining speechreading, decoding and phonology skills, Dr. Kelly recommends testing auditory discrimination with and without a visuomotor component in order to isolate the two.
Another emerging diagnostic trend is a better ability among clinicians working with this population to differentially diagnose CAPD from co-occurring disorders such as ADHD, dyslexia and language problems.
In a recent study Gail D. Chermak, PhD, CCC-A, FAAA, and other researchers confirmed that the diagnostic profiles of patients with ADHD and CAPD are distinctly different.2 Using input from pediatricians and audiologists, they found a clear differentiation between the behaviors that characterize these two conditions.
The scientists observed some overlap in their manifestations, however. For instance, audiologists noted some inattention and distractibility in the children with CAPD.
However, these behaviors, while prominent among children with ADHD, were considered less characteristic of children with CAPD. In contrast, children with CAPD were marked by difficulty hearing in background noise and following oral instruction.
Although assessment can become complicated, these findings "suggest that in the real world these differentiations can be made," said Dr. Chermak, Edward R. Meyer distinguished professor of audiology and chair in the Department of Speech and Hearing Sciences at Washington State University in Pullman.
In another study she and her colleagues identified the major differences between CAPD and ADHD. ADHD, they noted, is an output disorder involving an inability to control behavior, while CAPD is an input disorder in which perceptual details are not transmitted properly by the central auditory system to central processors.3
ADHD is thought of as a vigilance or sustained attention problem, while CAPD is considered a selective or divided attention problem, the scientists reported. The child with CAPD can sit and listen until competing noise is introduced, but sustaining attention becomes problematic for the child with ADHD, even in quiet.
They also suspect that ADHD spans sensory modalities, but more work needs to be done in this area.
Most of Dr. Kelly's patients present a combination of ADHD and CAPD.
"That's another reason we need a transdisciplinary approach to diagnosis," she said. "The speech-language pathologist does not diagnose ADHD."
Children who present attention problems related to CAPD typically have a problem with auditory attention alone, she said, while those with ADHD tend to have attention problems in all sensory areas.
Many forms of learning disabilities tend to be comorbid.
For this reason it's often wise to administer a comprehensive battery that looks at a number of auditory skills, Dr. Kelly suggested.
Clinicians must examine the audiological report for functioning of the central auditory nervous system and integrate it with a comprehensive speech-language pathology assessment.
One of the biggest challenges is integrating all of these elements and translating them into realistic goals, she said. The goals must be achievable and tailored for children with delays vs. disorders as well as for those in need of rehabilitation vs. habilitation.
Other factors that need to be considered when planning objectives are the age and motivation of the child, as well as flexibility within the setting in terms of programming, according to Dr. Kelly. The speech-language pathologist also must take into account cortical changes related to neural plasticity.
"Research tells us experience changes the brain," she said. "If you create a variety of repeated, quality experiences within appropriately targeted therapy of the type a child needs to build new cortical pathways, you can improve or augment central auditory processing skill areas and possibly create new cortical pathways."
There may be a number of ways to accomplish CAPD intervention.
Dr. Kelly advised giving children a foundation of lower-order skills, including attention, memory and discrimination, before progressing to higher-order processing skills.4
"More is not necessarily better," she noted. "Less therapy that is targeted and specific, even for significant and challenging cases, is often much more advisable than taking a child out for five 45-minute periods a week."
Three management approaches that have been used with success build vocabulary to address auditory closure problems; help memory, organization, and the transfer of auditory information; and provide informal auditory training.5
"Well-informed parents, teachers or tutors can learn these procedures with a minimum amount of instruction and training," Dr. Musiek said. "They do not necessarily have to be administered by speech-language pathologists or audiologists."
But these clinicians should play a leadership role in the training.
However, providing a detailed explanation of the procedures to those who will work with the child is critical to success. Literature, examples, and sometimes a tape recording of the discussions also are helpful.
"I do not believe you can teach individuals to follow through on these therapeutic plans unless you meet face to face," Dr. Musiek said. "We will not prescribe these kinds of things without that kind of an interaction."
"None of these approaches will be successful if there is only one member of the team," said Dr. Chermak, who collaborates with parents, teachers, speech-language pathologists, audiologists and other professionals, such as behavioral psychologists and reading teachers.
The cornerstone of a treatment program for a child with CAPD is very often some form of signal enhancement, such as an assistive listening device (ALD), coupled with auditory skill training, which builds temporal processing and listening-in-noise abilities, she said.
Another area of focus includes metacognitive and metalinguistic strategies, which involve teaching the child to monitor and use his or her central executive control strategies and linguistic resources to improve listening outcomes. These strategies can be used when an ALD is not available.6
A second metacognitive tool, the self-correction strategy, can be used if children hit a roadblock when learning new words. They reorganize their thinking and re-establish concentration.
Making appropriate referrals can be a confusing area for professionals.
If a child presents with CAPD as evidenced by a rigorous central auditory test battery and the diagnostic information from the physician and psychologist is in place, a referral should be made to a speech-language pathologist for metalinguistic and metacognitive management.
The speech-language pathologist implements most of the central auditory intervention, including metalinguistic and metacognitive approaches.
A referral should be made to an audiologist for auditory training and ALD fitting. While sophisticated training requires audiological equipment and acoustic control, auditory training can be accomplished by the speech-language pathologist or parents with the help of commercially available software, such as Earobics, from Cognitive Concepts, Inc., in Evanston, IL; Lindamood-Bell Learning Processes, from Lindamood-Bell, in San Luis Obispo, CA; and Fast ForWord®, from Scientific Learning Corp., in Berkeley, CA.
Simple, self-made materials also can be used, such as a cassette recording of noise that is played back while the child identifies consonants, vowels, syllables or real words.
"We encourage audiologists and speech-language pathologists to work together on auditory training," Dr. Chermak said.
There are several avenues for future research in CAPD. One involves looking at multiple system function. CAPD seems to be predominantly, if not specifically, an auditory system deficit, she noted, but that remains to be confirmed because most academic audiologists don't use a multimodality assessment battery with these children.
"We have assessed their auditory system and come to a conclusion as to whether they have CAPD, but we have not determined if these children have the same perceptual deficits in other sensory systems," she said. "We presume they don't and need to do more work to substantiate, confirm or refute."
Other domains need to be tested using measures that mirror testing in the auditory domain. For instance, a tachistoscopic test involves introducing stimuli into each hemisphere to determine if the child has a visual deficit similar to the auditory dichotic deficit.
1. Musiek, F., et al. (1999). Hit and false positive rates for the middle latency response in patients with central nervous system involvement. Journal of the American Academy of Audiology, Vol. 10., No. 5.
2. Chermak, G.D., Somers, E.K., & Seikel, J.A. (1998). Behavioral signs of central auditory processing disorders and attention deficit hyperactivity disorder. Journal of the American Academy of Audiology, Vol. 9, No. 1.
3. Chermak, G.D., Hall, J.W. III, & Musiek, F.E. (1999). Differential diagnosis and management of CAPD and ADHD. Journal of the American Academy of Audiology, Vol. 10, No. 6.
4. Kelly, D. (1995). Central Auditory Processing Disorder: Strategies for Use with Children and Adolescents. San Antonio: Communication Skill Builders.
5. Musiek, F. (1999). Habilitation and management of auditory processing disorders: Overview of selected procedures. Journal of the American Academy of Audiology, Vol. 10, No. 6.
6. Musiek, F., & Chermak, G. (1997). Central Auditory Processing Disorder: New Perspectives. San Diego: Singular Publishing.
For More Information
Gail D. Chermak, PhD, Department of Speech and Hearing Sciences, Washington State University, Pulman, WA 99164-2420; (509) 335-4525; e-mail: email@example.com
James W. Hall III, PhD, Vanderbilt Balance and Hearing Center, 1500 21st Ave. S., Ste. 2600, Nashville, TN 37212-3102; (615) 322-6389; e-mail firstname.lastname@example.org
Dorothy Kelly, DA, Department of Speech Communication, St. Joseph's College, 155 Roe Blvd., Patchogue, NY 11746; (516) 736-7530; e-mail: email@example.com
Frank E. Musiek, PhD, Dartmouth-Hitchock Medical Center, One Medical Center Dr., Lebanon, NH 03756; (603) 650-8125; e-mail: firstname.lastname@example.org
Marc Iskowitz is associate editor of ADVANCE.