Auditory Processing Disorder (APD): Progress in Diagnostics So Far. A Mini-Review on Imaging Techniques

Abstract

Auditory processing disorder (APD) is a disorder that affects the perception of sound, both verbal and non-verbal. Patients who are generally diagnosed with APD present with abnormal hearing but have normal audiograms. There is no gold standard investigation for APD and no standardized criteria for diagnosis. Because of its disabling effect and the overlap that exists with other neurodevelopmental disorders, there is an urgent need to develop tools and criteria for appropriate diagnosis. There is a current significant focus in research on imaging techniques that can possibly be used in the future for the appropriate diagnosis of APD. Over the years, several imaging techniques have contributed significantly to defining this disorder. To date, no studies have reported the routine use of imaging for the diagnosis of APD.

Abnormal Resting-State Quantitative Electroencephalogram in Children With Central Auditory Processing Disorder: A Pilot Study

“…Recently, imaging techniques have gained interest as potential methods for CAPD evaluation (Micallef, 2016 ). Investigating brain activity for clinical purposes is often associated with a dilemma of what paradigm should be applied.…”

“…Various symptoms and an unrecognized brain dysfunctions associated with CAPD entail a lack of consensus regarding the definition of CAPD (Dillon, 2012 ; Moore and Hunter, 2013 ; Moore et al, 2013 ). It has been recommended to include in the CAPD assessment a clinical history of the patient (Micallef, 2016 ), well-validated questionnaires to recognize real-life listening difficulties (Moore et al, 2013 ), and standardized verbal and non-verbal tests for measuring central auditory processing (Micallef, 2016 ). However, presently there is neither universally accepted CAP test battery nor specific cut-offs for CAPD evaluation.…”

“…Previous studies have shown that CAPD co-occurs with anatomical and/or functional brain abnormalities not only in the areas specialized in processing of acoustic information (Kim et al, 2009 ; Schmithorst et al, 2011 ; Owen et al, 2013 ; Farah et al, 2014 ; Pluta et al, 2014 ; Micallef, 2016 for a review). Kim et al ( 2009 ) have found that the auditory cortex atrophy was accompanied by an increase in the metabolism of the bilateral Heschl's gyrus and precuneus in an adult patient with listening difficulties.…”

Dichotic listening deficits in amblyaudia are characterized by aberrant neural oscillations in auditory cortex

“…Moreover, common manifestations of auditory symptoms in various disorders [e.g., attention-deficit/hyperactivity disorder (ADHD), dyslexia, or specific language impairment (SLI)] may arise from the same basic auditory deficits that make the differential diagnosis of these patients even more complicated (Gilley et al, 2016; Milner et al, 2018; Riccio et al, 1994; Sharma et al, 2009). APD may also produce functional and anatomical abnormalities that are not limited solely to the auditory pathways (Farah et al, 2014; Kim et al, 2009; Micallef, 2015; Owen et al, 2013; Pluta et al, 2014; Schmithorst et al, 2011). These limitations have motivated the use of objective approaches to define specific neural mechanisms that contribute to auditory-based learning disorders including APD.…”

Common Misconceptions Regarding Pediatric Auditory Processing Disorder

“…As an example, some European countries are still in the process of standardizing their auditory processing test battery or attempting to optimize inclusion of imaging in diagnostics [i.e., Ref. ( 2 – 4 )]. Consequently, many children with undiagnosed APD are struggling both in school and during out of school activities, with negative impact on their phonologic and prosodic communication, academics, psychosocial behavior, and social skills.…”