Effect of Quiet and Noise on P300 Response in Individuals with Auditory Neuropathy Spectrum Disorder

THIEME 462 Original Research Effect of Quiet and Noise on P300 Response in Individuals with Auditory Neuropathy Spectrum Disorder Kumari Apeksha1 Ajith U. Kumar2 1 Department of Speech and Hearing, JSS Institute of Speech & Hearing, Mysuru, India 2 Department of Audiology, All India Institute of Speech & Hearing, Mysuru, India Address for correspondence Kumari Apeksha, PhD, Lecturer, Department of Speech and Hearing, JSS Institute of Speech & Hearing, Mysuru, Karnataka, India (e-mail: ). Int Arch Otorhinolaryngol 2020;24(4):e462–e471. Abstract Keywords ► cortical potential ► P300 ► auditory neuropathy spectrum disorder ► scalp topographic analysis ► signal-to-noise ratio Introduction Auditory neuropathy spectrum disorder (ANSD) is a clinical condition in which individuals have normal cochlear responses and abnormal neural responses. There is a lack of evidence in the literature regarding the neural discrimination skill in individuals with ANSD, especially when the signal is presented in the presence of noise. Objectives The present study was performed with the aim to investigate auditory discrimination skill, in quiet and in the presence of noise, in individuals with ANSD and to compare the findings with normal-hearing individuals. Methods A total of 30 individuals with normal hearing sensitivity and 30 individuals with ANSD in the age range of 15 to 55 years old, with the mean age of 27.86 years old, were the participants. P300 response was recorded from both groups using syllable pairs /ba/-/da/ in oddball paradigm and the syllable /da/ in repetitive paradigm in quiet and at þ10 dB signal-to-noise ratio (SNR). Results There was significant prolongation in latency and reaction time, and reduction in amplitude of P300 response and sensitivity in both groups with the addition of noise. The topographic pattern analysis showed activation of the central-parietal-occipital region of the brain in individuals with ANSD, whereas activation of the central-parietal region was observed in individuals with normal hearing. The activation was more diffused in individuals with ANSD compared with that of individuals with normal hearing. Conclusion The individuals with ANSD showed a significantly more adverse effect of noise on the neural discrimination skill than the normal counterpart. Introduction with Objective Auditory neuropathy spectrum disorder (ANSD) is a clinical condition in which the individuals have an abnormality in the afferent auditory nervous system. The common site of lesion in individuals with ANSD includes inner hair cells and ribbon synapse (presynaptic disorder), unmyelinated auditory nerve dendrite, auditory ganglion cells and their axons (postsynaptic disorder), and the auditory brainstem pathway.1 Temporal bone studies have shown normal outer and inner hair cells with loss of auditory nerve fibers and/or demyelination of received July 12, 2019 accepted November 4, 2019 DOI https://doi.org/ 10.1055/s-0039-3402441. ISSN 1809-9777. fibers in adults with ANSD.2–4 The causes of ANSD can be categorized as having a genetic cause and an acquired cause. The genetic cause can be syndromic and nonsyndromic. Sininger5 reported 40% of the individuals with ANSD to have a genetic basis. The acquired causes of ANSD include hypoxia, prematurity, hyperbilirubinemia, immune response, infections, toxic substances, and nutritional deficiencies.6,7 The audiological test report shows normal to severe loss of hearing sensitivity as evident on pure-tone audiometry, presence of otoacoustic emission, abnormality in auditory brainstem Copyright © 2020 by Thieme Revinter Publicações Ltda, Rio de Janeiro, Brazil Effect of Quiet and Noise on P300 Response in Individuals response and middle ear muscle reflexes.8–10 It effects, primarily, the perception of auditory temporal information.11,12 The deficit in temporal encoding can impair sound localization and speech perception skills of the individuals.13 Several test reports have also shown abnormal encoding of speech at the cortical level.14–17 One of the commonly encountered problems by individuals with ANSD is speech perception in the presence of noise.10,18,19 The performance of the individuals with hearing impairment gets modulated by both auditory as well as cognitive capabilities.20,21 One of the cognitive components that help in speech perception is working memory. Working memory, also known as short-term memory, is the interplay between echoic memory and long-term memory. The working memory can be assessed using slow cortical potentials that have prolonged refractory periods. The P300 component of the auditory evoked potential is one of the commonly used measures to assess the capacity of the working memory. Appropriate attention to the stimuli and adequate memory processing speed is necessary for speech perception in adverse listening conditions.22–24 The attention toward the stimulus and the fundamental memory processing speed of the individual affects P300 amplitude and latency.25 P300 amplitude is determined by the gap between the two target stimuli compared with the stimulus probability.26 P300 amplitude also depends on the attention allocated to the task and the memory load.27,28 The amplitude reduces with increase in memory load as the task processing demand increases.25 The stimuli that receive more attention and get recognized with more confidence are associated with more amplitude of the P300 potential. P300 latency index classification speed is the time required to detect and respond to the target stimulus.11,29,30 P300 latency correlates positively/strongly with mental function speed.31,32 The superior the cognitive function of the individuals, the shorter the P300 latency. P300 potential is maximally recorded from the hippocampus, the superior temporal sulcus, the ventrolateral prefrontal cortex, and the intraparietal sulcus.33 Few researchers have investigated the speech processing ability in individuals with ANSD using different test measures (P1-N1-P2, MMN, and P300). In these studies, the auditory evoked responses were recorded from limited electrode sites.14–16,34–36 To our knowledge, there are only two studies reported in the literature that discuss the multichannel recording in individuals with ANSD.37,38 Apeksha et al37 recorded P300 response in individuals with ANSD for speech contrast /ba/-/da/, whereas Apeksha et al38 recorded P300 response in individuals with ANSD for the three different speech contrasts /ba/-/da/, /ba/-/ma/ and /ba/-/pa/. In both studies, the P300 response was recorded only in quiet listening condition. Since the individuals with ANSD find it difficult to perceive speech in the presence of noise, there was a need to explore the speech discrimination ability of individuals with ANSD in the presence of noise. Obtaining multichannel information in the presence of noise will give an insight into their cortical representation of speech perception ability in a noisy situation. Using highdens (...truncated)