Central auditory processing disorders in children and adults.

Central auditory processing disorders (CAPD) can affect children and adults of all ages due to a wide variety of causes. CAPD is a neurobiologic deficit in the central auditory nervous system (CANS) that affects those mechanisms that underlie fundamental auditory perception, including localization and lateralization; discrimination of speech and non-speech sounds; auditory pattern recognition; temporal aspects of audition, including integration, resolution, ordering, and masking; and auditory performance with competing and/or degraded acoustic signals (American Speech-Language-Hearing Association, 2005a, b). Although it is recognized that central auditory dysfunction may coexist with other disorders, CAPD is conceptualized as a sensory-based auditory disorder. Administration of behavioral and/or electrophysiologic audiologic tests that have been shown to be sensitive and specific to dysfunction of the CANS is critical for a proper diagnosis of CAPD, in addition to assessments and collaboration with a multidisciplinary team. Intervention recommendations for CAPD diagnosis are based on the demonstrated auditory processing deficits and related listening and related complaints. This chapter provides an overview of current definitions and conceptualizations, methods of diagnosis of, and intervention for, CAPD. The chapter culminates with a case study illustrating pre- and posttreatment behavioral and electrophysiologic diagnostic findings.

Efficacy of auditory interventions for central auditory processing disorder: a response to Fey et al. (2011).

PURPOSE: To provide a commentary on "Auditory Processing Disorder and Auditory/Language Interventions: An Evidence-Based Systematic Review" by Fey et al. (2011). METHOD: Examination of the conclusions drawn by Fey et al. (2011) in the context of the American Academy of Audiology (2010a, 2010b) and American Speech-Language-Hearing Association (2005a, 2005b, 2005c) guidelines for the diagnosis and treatment of auditory processing disorder, the evidence cited therein, and other pertinent published reports. RESULTS: The review provided by Fey et al. (2011) is limited due to the exclusion of pertinent efficacy studies from their analysis, inclusion of studies that did not employ strictly auditory-based therapies, and lack of well-defined experimental groups in many of the studies cited. Further, the questions posed by their literature review may not have addressed the efficacy of true auditory interventions in the remediation of auditory difficulties in children who have primary deficits in central auditory processing. CONCLUSION: A more comprehensive review than that done by Fey et al. (2011) would have better addressed the fundamental question of the efficacy of direct remediation activities for children with central auditory processing disorder.

Performance of normal adults and children on central auditory diagnostic tests and their corresponding visual analogs.

BACKGROUND: It has been suggested that, in order to validate a diagnosis of (C)APD (central auditory processing disorder), testing using direct cross-modal analogs should be performed to demonstrate that deficits exist solely or primarily in the auditory modality (McFarland and Cacace, 1995; Cacace and McFarland, 2005). This modality-specific viewpoint is controversial and not universally accepted (American Speech-Language-Hearing Association [ASHA], 2005; Musiek et al, 2005). Further, no such analogs have been developed to date, and neither the feasibility of such testing in normally functioning individuals nor the concurrent validity of cross-modal analogs has been established. PURPOSE: The purpose of this study was to investigate the feasibility of cross-modal testing by examining the performance of normal adults and children on four tests of central auditory function and their corresponding visual analogs. In addition, this study investigated the degree to which concurrent validity of auditory and visual versions of these tests could be demonstrated. RESEARCH DESIGN: An experimental repeated measures design was employed. STUDY SAMPLE: Participants consisted of two groups (adults, n=10; children, n=10) with normal and symmetrical hearing sensitivity, normal or corrected-to-normal visual acuity, and no family or personal history of auditory/otologic, language, learning, neurologic, or related disorders. DATA COLLECTION AND ANALYSIS: Visual analogs of four tests in common clinical use for the diagnosis of (C)APD were developed (Dichotic Digits [Musiek, 1983]; Frequency Patterns [Pinheiro and Ptacek, 1971]; Duration Patterns [Pinheiro and Musiek, 1985]; and the Random Gap Detection Test [RGDT; Keith, 2000]). Participants underwent two 1 hr test sessions separated by at least 1 wk. Order of sessions (auditory, visual) and tests within each session were counterbalanced across participants. ANOVAs (analyses of variance) were used to examine effects of group, modality, and laterality (for the Dichotic/Dichoptic Digits tests) or response condition (for the auditory and visual Frequency Patterns and Duration Patterns tests). Pearson product-moment correlations were used to investigate relationships between auditory and visual performance. RESULTS: Adults performed significantly better than children on the Dichotic/Dichoptic Digits tests. Results also revealed a significant effect of modality, with auditory better than visual, and a significant modality×laterality interaction, with a right-ear advantage seen for the auditory task and a left-visual-field advantage seen for the visual task. For the Frequency Patterns test and its visual analog, results revealed a significant modality×response condition interaction, with humming better than labeling for the auditory version but the reversed effect for the visual version. For Duration Patterns testing, visual performance was significantly poorer than auditory performance. Due to poor test-retest reliability and ceiling effects for the auditory and visual gap-detection tasks, analyses could not be performed. No cross-modal correlations were observed for any test. CONCLUSIONS: Results demonstrated that cross-modal testing is at least feasible using easily accessible computer hardware and software. The lack of any cross-modal correlations suggests independent processing mechanisms for auditory and visual versions of each task. Examination of performance in individuals with central auditory and pan-sensory disorders is needed to determine the utility of cross-modal analogs in the differential diagnosis of (C)APD.

The utility of visual analogs of central auditory tests in the differential diagnosis of (central) auditory processing disorder and attention deficit hyperactivity disorder.

BACKGROUND: Cacace and McFarland (2005) have suggested that the addition of cross-modal analogs will improve the diagnostic specificity of (C)APD (central auditory processing disorder) by ensuring that deficits observed are due to the auditory nature of the stimulus and not to supra-modal or other confounds. Others (e.g., Musiek et al, 2005) have expressed concern about the use of such analogs in diagnosing (C)APD given the uncertainty as to the degree to which cross-modal measures truly are analogous and emphasize the nonmodularity of the CANs (central auditory nervous system) and its function, which precludes modality specificity of (C)APD. To date, no studies have examined the clinical utility of cross-modal (e.g., visual) analogs of central auditory tests in the differential diagnosis of (C)APD. PURPOSE: This study investigated performance of children diagnosed with (C)APD, children diagnosed with ADHD (attention deficit hyperactivity disorder), and typically developing children on three diagnostic tests of central auditory function and their corresponding visual analogs. The study sought to determine whether deficits observed in the (C)APD group were restricted to the auditory modality and the degree to which the addition of visual analogs aids in the ability to differentiate among groups. RESEARCH DESIGN: An experimental repeated measures design was employed. STUDY SAMPLE: Participants consisted of three groups of right-handed children (normal control, n=10; ADHD, n=10; (C)APD, n=7) with normal and symmetrical hearing sensitivity, normal or corrected-to-normal visual acuity, and no family or personal history of disorders unrelated to their primary diagnosis. Participants in Groups 2 and 3 met current diagnostic criteria for ADHD and (C)APD. DATA COLLECTION AND ANALYSIS: Visual analogs of three tests in common clinical use for the diagnosis of (C)APD were used (Dichotic Digits [Musiek, 1983]; Frequency Patterns [Pinheiro and Ptacek, 1971]; and Duration Patterns [Pinheiro and Musiek, 1985]). Participants underwent two 1 hr test sessions separated by at least 1 wk. Order of sessions (auditory, visual) and tests within each session were counterbalanced across participants. ANCOVAs (analyses of covariance) were used to examine effects of group, modality, and laterality (Dichotic/Dichoptic Digits) or response condition (auditory and visual patterning). In addition, planned univariate ANCOVAs were used to examine effects of group on intratest comparison measures (REA, HLD [Humming-Labeling Differential]). RESULTS: Children with both ADHD and (C)APD performed more poorly overall than typically developing children on all tasks, with the (C)APD group exhibiting the poorest performance on the auditory and visual patterns tests but the ADHD and (C)APD group performing similarly on the Dichotic/Dichoptic Digits task. However, each of the auditory and visual intratest comparison measures, when taken individually, was able to distinguish the (C)APD group from both the normal control and ADHD groups, whose performance did not differ from one another. CONCLUSIONS: Results underscore the importance of intratest comparison measures in the interpretation of central auditory tests (American Speech-Language-Hearing Association [ASHA], 2005 ; American Academy of Audiology [AAA], 2010). Results also support the "non-modular" view of (C)APD in which cross-modal deficits would be predicted based on shared neuroanatomical substrates. Finally, this study demonstrates that auditory tests alone are sufficient to distinguish (C)APD from supra-modal disorders, with cross-modal analogs adding little if anything to the differential diagnostic process.

The relationship between brainstem temporal processing and performance on tests of central auditory function in children with reading disorders.

PURPOSE: Studies using speech stimuli to elicit electrophysiologic responses have found approximately 30% of children with language-based learning problems demonstrate abnormal brainstem timing. Research is needed regarding how these responses relate to performance on behavioral tests of central auditory function. The purpose of the study was to investigate performance of children with dyslexia with and without abnormal brainstem timing and children with no history of learning or related disorders on behavioral tests of central auditory function. METHOD: Performance of 30 school-age children on behavioral central auditory tests in common clinical use was examined: Group 1 (n = 10): dyslexia, abnormal brainstem timing; Group 2 (n = 10): dyslexia, normal brainstem timing; Group 3 (n = 10): typical controls. RESULTS: Results indicated that all participants in Group 2 met diagnostic criteria for (central) auditory processing disorder [(C)APD], whereas only 4 participants in Group 1 met criteria. The Biological Marker of Auditory Processing (BioMARK) identified 6 children in Group 1 who did not meet diagnostic criteria for (C)APD but displayed abnormal brainstem timing. CONCLUSIONS: Results underscore the importance of central auditory assessment for children with dyslexia. Furthermore, the BioMARK may be useful in identifying children with central auditory dysfunction who would not have been identified using behavioral methods of (C)APD assessment.

Hemispheric lateralization of bilaterally presented homologous visual and auditory stimuli in normal adults, normal children, and children with central auditory dysfunction.

Two experiments were conducted to examine the performance of normal adults, normal children, and children diagnosed with central auditory dysfunction presumed to involve the interhemispheric pathways on a dichotic digits test in common clinical use for the diagnosis of central auditory processing disorder (CAPD) and its corresponding visual analog. Results of the first experiment revealed a significant right ear advantage (REA) for the dichotic listening task and a left-visual-field advantage (LVFA) for the corresponding visual analog in normal adults and children. In the second experiment, results revealed a significantly larger REA in the children with CAPD as compared to the normal children. Results also revealed a reversed cerebral asymmetry (RVFA) for the children with CAPD on the visual task. Significant cross-modal correlations suggest that the two tasks may reflect, at least in part, similar interhemispheric processing mechanisms in children. Findings are discussed in relation to differential diagnosis and modality-specificity of CAPD.

Nonmodularity of the central auditory nervous system: implications for (central) auditory processing disorder.

This response to A. T. Cacace and D. J. McFarland (2005) identifies points of agreement and disagreement regarding the concept of modularity in the diagnosis of (central) auditory processing disorder [(C)APD]. We concur that the evaluation of (C)APD must take into consideration the influence of higher order global or pansensory issues on performance on tests of central auditory function. To accomplish this goal, multidisciplinary (e.g., multimodal) testing is an integral part of differential diagnosis of (C)APD. We also agree that the efficiency of diagnostic tests of (C)APD should not be evaluated by imprecise criteria [e.g., "presumed" or "suspected" (C)APD], which do not provide accurate measures of the true sensitivity and specificity of these tests. Our conceptualization and recommendations for clinical practice in this area diverge, however, from that of Cacace and McFarland in a number of pivotal ways. Based on the current limitations of multimodal assessment relative to issues related to scope of practice and test efficiency, as well as the accumulated basic science and clinical literature that demonstrates the nonmodularity and interactive organization of the brain, we recommend use of the sensitized test battery of the central auditory nervous system (CANS) in combination with multidisciplinary testing to differentially diagnose (C)APD and to guide treatment of the disorder. We assert that sensitivity and specificity measures derived from individuals with well-circumscribed lesions of the CANS provide an important guide to establishing the validity of central auditory diagnostic tests. We note that researchers in the area of auditory science and (C)APD must acknowledge the challenges of the clinical arena, and we encourage their continued help to develop diagnostic tools that are both efficient and practical for the differential diagnosis of (C)APD. We conclude that our approach, which combines multidisciplinary evaluation and specific tests of central auditory function that have demonstrated sensitivity and specificity for disorders of the CANS, allows us to identify (and thus rehabilitate) the auditory deficits present in individuals with (C)APD in its "purest" form. It also permits the identification and rehabilitation of auditory deficits in individuals who exhibit auditory perceptual problems that coexist with other processing problems, while ruling out those who perform poorly on auditory tests because of a global, supramodal problem involving cognition, attention, language, memory, or related skills.