CHCS - Perspectives Winter/Spring 2016

COLLEGE OF HEALTH CARE SCIENCES • 15 Jackie M. Davie, Ph.D., CCC-A, and Sarah Wakefield, Au.D., who serve as associate professors and faculty preceptors in the NSU Audiology Clinic, are conducting a study to assess the outcomes of auditory processing disorders (APD) evaluation in order to better understand the location of dysfunction within the central auditory nervous system. Davie has worked as a pediatric audiological researcher for the past 19 years, primarily studying middle-ear function in infants and children with ear infections. Wakefield has been involved in assessing auditory processing disorders for the past seven years and began researching in the same field three years ago. The central auditory nervous system (CANS) is orga- nized to include redundancy in its pathway, which helps make the system less susceptible to functional deficits if a lesion exists. In children, however, the CANS does not completely mature until puberty, somewhat negating the positive impact of the pathway redundancy. If a lesion exists prior to maturation, children can display difficulties with their ability to listen and comprehend. These deficits are frequently classified as an auditory processing disorder. The definition and assessment of APD is a somewhat contentious area of debate within the field of audiology and child development. Part of the contention is due to a lack of research, which defines the precise etiology of the disorder. For example, is there a single locus of dysfunc- tion confined to the central auditory system or is it more of a spectrum of processing difficulties? Are there deficits cortical in nature (top-down), such as language, or attention oriented? Or is this a result of a breakdown in lower-level sensory processing (bottom-up) of auditory stimuli? Currently, the researchers are evaluating the possible site of dysfunction in the central auditory nervous system by analyzing previously collected clinical data. As part of the auditory processing testing battery used at NSU, testing includes both low-brainstem level electrophysiological and higher-cortical level behavioral testing procedures. At the low brainstem level, testing consists of acoustic reflexes. The response for this test is received through the superior olivary complex in the pons and provides data about low-brainstem level auditory integration. Behavioral procedures consist of a variety of tests examining auditory closure, auditory integration, auditory separation, pattern perception, gap detection, and selective auditory attention. In order to evaluate for patterns in results, medical charts were reviewed for the children who were assessed for auditory process- ing disorders. Data was evaluated using descriptive analysis of the test results in comparison to the various APD profiles. More than 300 APD evaluations have been completed in the past five years in the NSU Audiology Clinic. Preliminary results revealed a higher-than-expected pattern of elevated/absent acoustic reflexes for certain APD profiles. Due to a higher-than-expected number of children with elevated acoustic reflexes, and in light of other normal peripheral measures, abnormal func- tion at the level of the super olivary complex, or even the efferent auditory system, is suspected. Further evaluation into superior olivary complex and efferent function is warranted, including prospective evaluation of electrophysiological function, auditory brainstem, and cortical-evoked potentials. ■ Auditory Acoustic Reflex Patterns in Children with APD Jackie M. Davie (seated) and Sarah Wakefield