Sharon Abel, PhD Jane Baran, PhD Anthony Cacace, PhD Gail Chermak, PhD$ Susan Dalebout, PhD Jay Hall 111, PhD Linda Hood, PhD Lisa Hunter, PhD James Jerger, PhD Susan Jerger, PhD Robert Keith, PhD Frank Musiek, PhD Ross Roeser, PhD Christine Sloan, PhD University of Toronto, Toronto, ON University of Massachusetts, Amherst, MA Albany Medical College, Albany, NY Washington State University, Pullman, WA University of Virginia, Charlottesville,VA University of Florida, Gainesville, FL Louisiana State University Medical Center, New Orleans, LA University of Minnesota, Minneapolis, MN University of Texas at Dallas, Dallas, TX University of Texas at Dallas, Dallas, TX University of Cincinnati, Cincinnati, OH Dartmouth-Hitchcock Medical Center, Hanover, NH University of Texas at Dallas, Dallas, TX Annapolis Valley Regional School Board Berwick, NS

Report of the Consensus Conference on the Diagnosis of Auditory Processing Disorders in School-Aged Children.

Auditory evoked potentials (AEPs) and behavioral tests were used to evaluate auditory processing in 10 children aged 7 to 11 years who were diagnosed as learning disabled (LD). AEPs included auditory brainstem responses (ABRs), middle latency responses (MLRs), and late cortical responses (P1, N1, P2, P3). Late cortical responses were recorded using an active listening oddball procedure. Auditory processing disorders were suspected in the LD children after a psychologist found phonologic processing and auditory memory problems. A control group of 10 age- and gender-matched children with no hearing or reported learning difficulties was also tested. Teacher ratings of classroom listening and SCAN Competing Words and Staggered Spondaic Word scores were poorer in the LD children. There were minor ABR latency differences between the two groups. Wave Na of the MLR was later and Nb was smaller in the LD group. The main differences in cortical responses were that P1 was earlier and P3 was later and smaller in the LD group.

Auditory brainstem response, middle latency response, and late cortical evoked potentials in children with learning disabilities

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 disord...

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

This case study involves a 41-year-old female who had sustained a mild traumatic brain injury during a horseback riding accident. The patient was seen for medical and neuropsychological testing following this incident and was referred to a speech-language pathologist for rehabilitative services. At 13 months posttrauma, the patient, who was frustrated by a lack of significant progress, requested an audiologic work-up. Results of testing conducted at this time revealed normal peripheral hearing and significant central auditory deficits. Based on these findings, an auditory rehabilitation program was developed and implemented. The components of this patient's rehabilitation program are reviewed, and the posttherapy improvements noted in her auditory functions are detailed. The case is important in that it demonstrates (1) that auditory deficits can be a sequel to minor head injury, (2) that these deficits are often subtle and may not be detected unless central auditory testing is conducted, and (3) that these deficits may be amenable to remediation.

Assessment and remediation of an auditory processing disorder associated with head trauma.

The pure-tone audiogram, though fundamental to audiology, presents limitations, especially in the case of central auditory involvement. Advances in auditory neuroscience underscore the considerably larger role of the central auditory nervous system (CANS) in hearing and related disorders. Given the availability of behavioral audiological tests and electrophysiological procedures that can provide better insights as to the function of the various components of the auditory system, this perspective piece reviews the limitations of the pure-tone audiogram and notes some of the advantages of other tests and procedures used in tandem with the pure-tone threshold measurement. To review and synthesize the literature regarding the utility and limitations of the pure-tone audiogram in determining dysfunction of peripheral sensory and neural systems, as well as the CANS, and to identify other tests and procedures that can supplement pure-tone thresholds and provide enhanced diagnostic insight, especially regarding problems of the central auditory system. A systematic review and synthesis of the literature. The authors independently searched and reviewed literature (journal articles, book chapters) pertaining to the limitations of the pure-tone audiogram. The pure-tone audiogram provides information as to hearing sensitivity across a selected frequency range. Normal or near-normal pure-tone thresholds sometimes are observed despite cochlear damage. There are a surprising number of patients with acoustic neuromas who have essentially normal pure-tone thresholds. In cases of central deafness, depressed pure-tone thresholds may not accurately reflect the status of the peripheral auditory system. Listening difficulties are seen in the presence of normal pure-tone thresholds. Suprathreshold procedures and a variety of other tests can provide information regarding other and often more central functions of the auditory system. The audiogram is a primary tool for determining type, degree, and configuration of hearing loss; however, it provides the clinician with information regarding only hearing sensitivity, and no information about central auditory processing or the auditory processing of real-world signals (i.e., speech, music). The pure-tone audiogram offers limited insight into functional hearing and should be viewed only as a test of hearing sensitivity. Given the limitations of the pure-tone audiogram, a brief overview is provided of available behavioral tests and electrophysiological procedures that are sensitive to the function and integrity of the central auditory system, which provide better diagnostic and rehabilitative information to the clinician and patient.

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Perspectives on the Pure-Tone Audiogram.

We sought to determine the test efficiency of the middle latency evoked response for identifying or differentiating subjects with and without central nervous system (CNS) involvement. Receiver operating characteristic curves were established for hit and false-positive rates for 26 subjects with CNS lesions and 26 control subjects matched for age and hearing sensitivity . The lesions involved but were not limited to the auditory regions of the CNS . Middle latency evoked response latency and amplitude measurements were made for the Na and Pa waves recorded at C3 and Ca electrode sites following stimulation of the left and right ears. Intrasubject comparisons were made for ipsilateral and contralateral stimulation/recording conditions. Amplitude measures were superior to latency measures . For amplitude, percentage differences from contralateral comparisons proved to be the most sensitive and specific measure . The clinical implications of findings are discussed.

Tim Kelly

Papers

Hit and False-Positive Rates for the Middle Latency Response in Patients with Central Nervous System Involvement