Brainstem evoked auditory potentials with speech stimulus in the auditory processing disorder

Abstract

Al though the clinical use of click stimuli to assess auditory function at the brainstem is already established, and numerous research projects use such stimuli to study human hearing, little is known about the auditory processing of a complex stimulus like speech. Aim: This study aimed at validating the speech stimulus as an effective method to evaluate speech auditory processing, to help us better understand its disorders. Materials and Methods:This prospective clinical study tested 20 subjects with Auditory Processing Disorders (APD) and 20 subjects with normal development (ND -control group) using the Brainstem Auditory Evoked Potentials with clicks and speech stimuli. The latter is based on first 40ms of the spoken syllable /da/. Results: No differences were observed between the groups regarding the click stimulus. However, with the speech stimulus the APD group presented latency delay and lower amplitudes when compared to the ND group. Conclusion: Speech stimulus proved to be more sensitive for the evaluation of Auditory Processing Disorders, showing possible alterations in synchronicity and speech processing neural input speed, especially as to the linguistic information of the latter.

Efficacy of Auditory Training Using the Auditory Brainstem Response to Complex Sounds: Auditory Processing Disorder and Specific Language Impairment

“…Previous studies about c-ABR in silence in children with learning and language impairment disorders, (C)APD, and autism have shown delayed latencies of onset peaks and shallower VA slopes [25,26,36] for these populations, which indicate that these children have synchrony deficits in brainstem neural responses to complex sounds. However, the current study did not point out significant differences in c-ABR in silence among groups, except for the APD group, which presented shallower VA slopes than the other groups.…”

“…The c-ABR provides direct information on the decoding of speech sound structure by the auditory nervous system because the brainstem response reflects the acoustic features of the stimulus (frequency and duration) with exceptional precision [22,23]. Numerous studies have demonstrated deficits in the c-ABR, especially during background noise in children with APD, learning impairment, and autism, and also improvements after AT in these populations [20,24,25,26,27,28]. …”

Masking Level Difference and Electrophysiological Evaluation in Adults with Normal Hearing

“…The literature pointed out that the FFR was more sensitive for the evaluation of the CAP, indicating possible alterations in the synchrony and speed of neural impulses in the speech processing, mainly regarding the linguistic information of such impulses. 33 Furthermore, recent studies have shown that there is a probability of 85.15% of subjects with altered FFR to present Central Auditory Processing Disorder. 34 It is noteworthy that an earlier study demonstrated that, in some individuals, the C wave does not appear as a stable component.…”

Evaluación electrofisiológica del procesamiento auditivo

“…En menores con trastornos del aprendizaje (TEA), se ha evidenciado que el complejo V-Va ha obtenido una pendiente significativamente menor, latencias aumentadas y/o amplitudes disminuidas en comparación a pares de la misma edad, pero sin dificultades de aprendizaje 12 . Este hallazgo sería común para niños con TPA, en los cuales también se ha documentado un aumento de latencia y disminuciones de amplitud para el complejo V-Va, además de una amplitud disminuida para el componente C en comparación a sujetos sin quejas de procesamiento auditivo 13 . Otro componente que ha demostrado ser un elemento diferenciador entre menores con TEA es el FFR, el cual tendría una amplitud disminuida en relación con pares sin dificultades 12 .…”

“…Estos antecedentes posicionan a los cABR como una potente herramienta para el estudio del procesamiento auditivo, trastornos de lenguaje y del aprendizaje en general, ya que, al menos el complejo V-Va y el FFR, son independientes de las habilidades cognitivas y de la inteligencia del sujeto evaluado, por lo que entregarían información exclusivamente auditiva logrando, además, diferenciar sujetos con alteración de normales. Otras técnicas, como los ABR clásicos mediante estímulo clic o estímulos frecuenciales, a pesar de reflejar actividad subcortical y no dependen de habilidades cognitivas, no lograría retratar esta última diferenciación 13 . A pesar de sus posibles utilidades, no se han encontrado valores o reportes de sensibilidad y especificidad de los cABR para ningún tipo de condición patológica.…”