Mismatch negativity in children with specific language impairment and auditory processing disorder

IntroductionMismatch negativity, an electrophysiological measure, evaluates the brain's capacity to discriminate sounds, regardless of attentional and behavioral capacity. Thus, this auditory event-related potential is promising in the study of the neurophysiological basis underlying auditory processing.ObjectiveTo investigate complex acoustic signals (speech) encoded in the auditory nervous system of children with specific language impairment and compare with children with auditory processing disorders and typical development through the mismatch negativity paradigm.MethodsIt was a prospective study. 75 children (6–12 years) participated in this study: 25 children with specific language impairment, 25 with auditory processing disorders, and 25 with typical development. Mismatch negativity was obtained by subtracting from the waves obtained by the stimuli /ga/ (frequent) and /da/ (rare). Measures of mismatch negativity latency and two amplitude measures were analyzed.ResultsIt was possible to verify an absence of mismatch negativity in 16% children with specific language impairment and 24% children with auditory processing disorders. In the comparative analysis, auditory processing disorders and specific language impairment showed higher latency values and lower amplitude values compared to typical development.ConclusionThese data demonstrate changes in the automatic discrimination of crucial acoustic components of speech sounds in children with specific language impairment and auditory processing disorders. It could indicate problems in physiological processes responsible for ensuring the discrimination of acoustic contrasts in pre-attentional and pre-conscious levels, contributing to poor perception.     

Auditory perceptual problems in non-organic hearing disorder

A series of 22 patients who presented with non-organic hearing disorder were examined for auditory perceptual problems. A test battery that examined eight areas of auditory perception revealed significant auditory perceptual problems in each of the 22 patients. The results indicate a view that differs from the traditional view of non-organic hearing disorder as either conscious feigning of a hearing disorder or an unconscious symptom of an unidentified emotional disorder. The information presented here indicates that specific auditory processing disorders could adversely affect patients' hearing and that auditory perceptual disorders could be diagnosed and treated.     

A review of objective methods of evaluating auditory neural pathways

OBJECTIVES: Review physiological methods of evaluating function of the auditory neural pathways in infants, children, and adults. Present two case studies to demonstrate the usefulness of physiological measures in assessing abnormalities of the auditory neural pathways. STUDY DESIGN: Review of applications of physiological measures of auditory neural function. METHODS: Review otoacoustic emissions, auditory evoked potentials, and efferent reflexes, and discuss their use in identifying disorders of the auditory neural pathways from the cochlea to the cortex. RESULTS: Auditory disorders occur from peripheral to central areas of the neural system. Patients with disorders of the peripheral nerve and/or the input from the cochlear inner hair cells, such as the patients presently described as having auditory neuropathy, demonstrate abnormal efferent reflexes, including middle ear muscle reflexes and efferent suppression of otoacoustic emissions, as well as grossly abnormal brainstem evoked potentials. In contrast, patients with more central disorders can be differentiated by normal results on tests of the neural periphery and abnormal findings on cortical evoked potentials and other measures of central function. CONCLUSIONS: Physiological measures are sensitive, objective, and less variable in assessing neural disorders than traditional behavioral measures such as pure-tone or speech audiometry.     

Validation of the pediatric speech intelligibility test in children with central nervous system lesions

The pediatric speech intelligibility (PSI) test was administered to 21 children with a variety of documented central nervous system (CNS) lesions. Ages ranged from 3 to 8 years. PSI test results demonstrated both high sensitivity and high specificity. Results were consistently (1) abnormal in children with lesions in areas of the brain important for auditory function (CNS auditory disorders) and (2) normal in children with lesions in areas anatomically remote from auditory nuclei and pathways (nonauditory CNS disorders).     

Validation of the Pediatric Speech Intelligibility Test in Children with Central Nervous System Lesions

The pediatric speech intelligibility (PSI) test was administered to 21 children with a variety of documented central nervous system (CNS) lesions. Ages ranged from 3 to 8 years. PSI test results demonstrated both high sensitivity and high specificity. Results were consistently (1) abnormal in children with lesions in areas of the brain important for auditory function (CNS auditory disorders) and (2) normal in children with lesions in areas anatomically remote from auditory nuclei and pathways (nonauditory CNS disorders).     

Auditory dysfunction in stroke

The auditory and vestibular systems share the same end organ and cranial nerve, yet vestibular signs and symptoms are common with stroke, whereas hearing disturbances are much less frequent. Several reasons would appear to account for this striking dissimilarity. One is that the auditory pathway is less ubiquitous than the vestibular pathways. The likelihood that a stroke involves the auditory pathway is, therefore, less on this basis alone. A second difference, to our knowledge not previously reported, is that the auditory pathway is often spared by the most common strokes. This is because major parts of the auditory pathway, such as the cochlear nucleus, inferior colliculus and medial geniculate body, have multiple sources of blood supply. A third well-recognized factor is the redundancy of the central auditory system and its strong bilateral representation above the level of the cochlear nuclei. Consequently, rostral to the cochlear nuclei gross deficits in hearing, such as those measured by standard pure-tone audiometry and speech discrimination, only occur if lesions are bilateral. Furthermore, widespread bilateral lesions of the auditory system typically render the patient unable to respond or are incompatible with life. In contrast, language disorders are more frequent because language is usually unilaterally represented in the cortex. Certainly, cerebral stroke often includes the auditory system, resulting in various types of auditory disorders, but most hemispherical lesions produce subtle hearing dysfunctions that can only be detected with sophisticated psychoacoustic and electrophysiological testing. The purpose of this review is to provide an overview of the auditory system and its blood supply and to review how auditory processing can be affected by stroke. Psychoacoustic and electrophysiological test procedures for identifying lesions in the central auditory system are described. The literature of hearing disorders due to stroke is reviewed and illustrative cases are presented.     

Auditory Dysfunction in Stroke

The auditory and vestibular systems share the same end organ and cranial nerve, yet vestibular signs and symptoms are common with stroke, whereas hearing disturbances are much less frequent. Several reasons would appear to account for this striking dissimilarity. One is that the auditory pathway is less ubiquitous than the vestibular pathways. The likelihood that a stroke involves the auditory pathway is, therefore, less on this basis alone. A second difference, to our knowledge not previously reported, is that the auditory pathway is often spared by the most common strokes. This is because major parts of the auditory pathway, such as the cochlear nucleus, inferior colliculus and medial geniculate body, have multiple sources of blood supply. A third well-recognized factor is the redundancy of the central auditory system and its strong bilateral representation above the level of the cochlear nuclei. Consequently, rostral to the cochlear nuclei gross deficits in hearing, such as those measured by standard pure-tone audiometry and speech discrimination, only occur if lesions are bilateral. Furthermore, widespread bilateral lesions of the auditory system typically render the patient unable to respond or are incompatible with life. In contrast, language disorders are more frequent because language is usually unilaterally represented in the cortex. Certainly, cerebral stroke often includes the auditory system, resulting in various types of auditory disorders, but most hemispherical lesions produce subtle hearing dysfunctions that can only be detected with sophisticated psychoacoustic and electrophysiological testing. The purpose of this review is to provide an overview of the auditory system and its blood supply and to review how auditory processing can be affected by stroke. Psychoacoustic and electrophysiological test procedures for identifying lesions in the central auditory system are described. The literature of hearing disorders due to stroke is reviewed and illustrative cases are presented.     

Results of brainstem evoked response in patients with vestibular complaints

Otoneurological evaluations are based on tests which investigate auditory and vestibular disorders, including brainstem evoked auditory potentials and vecto-electronystagmography.     

Evaluation of auditory processing and phonemic discrimination in children with normal and disordered phonological development

Auditory processing and phonemic discrimination are essential for communication. Type of study: Retrospective.AimTo evaluate auditory processing and phonemic discrimination in children with normal and disordered phonological development.Material and MethodsAn evaluation of 46 children was carried out: 22 had phonological disorders and 24 had normally developing speech. Diotic, monotic and dichotic tests were applied to assess auditory processing and a test to evaluate phonemic discrimination abilities.DesignCross-sectional, contemporary.ResultsThe values of normally-developing children were within the normal range in all auditory processing tests; these children attained maximum phonemic discrimination test scores. Children with phonological disorders performed worse in the latter, and presented disordered auditory processing.ConclusionAuditory processing and phonemic discrimination in children with phonological disorders are altered.     

Auditory brain stem response and child attention deficit hyperactivity disorder

Diagnostic audiological test performed in two children showed remarkable differences between the results of behavioral audiometry and those of auditory evoked response audiometry. The results of neuropsychological evaluation showed attention disorders. It is possible that a response desynchronisation in the auditory pathway may exist in these disorders. Interpretation of ABR findings can be problematic in children with learning disabilities or minimal cerebral dysfunction.     

Normal intelligibility functions for the Auditec CID W-22 test at 30% and 60% time-compression

Time-compressed speech has been used to identify the site of central auditory disorders and auditory processing problems. Some authors suggest that the determination of audiometric normalcy should include satisfactory performance on a speech intelligibility test sensitive to central auditory dysfunction, such as time-compressed speech. Before scores from patients with auditory disorders can be meaningfully interpreted, however, it is necessary to establish normal performance on standardized recordings. Thus, this study was undertaken to generate speech intelligibility functions in a normal-hearing population using the Auditec CID W-22 recordings with 30% and 60% time-compression. The 30% condition revealed a slope of 3.24% per decibel and the function approached a plateau at 35 dB sensation level (SL). The 60% condition produced a function that increased gradually at 1.8% per decibel over the 20 to 80% intelligibility range. An intelligibility score of 82% was observed at 46 dB SL where the function approached an asymptote. These functions provide a standard against which subjects with central auditory dysfunctions can be compared. The relative difficulty that normal subjects had with the 60% time-compressed speech suggests that this condition may be too difficult for some subjects with central auditory disorders.     

A Dominantly Inherited Progressive Deafness Affecting Distal Auditory Nerve and Hair Cells

We have studied 72 members belonging to a large kindred with a hearing disorder inherited in an autosomal dominant pattern. We used audiological, physiological, and psychoacoustic measures to characterize the hearing disorders. The initial phenotypic features of the hearing loss are of an auditory neuropathy (AN) with abnormal auditory nerve and brainstem responses (ABRs) and normal outer hair cell functions [otoacoustic emissions (OAEs) and cochlear microphonics (CMs)]. Psychoacoustic studies revealed profound abnormalities of auditory temporal processes (gap detection, amplitude modulation detection, speech discrimination) and frequency processes (difference limens) beyond that seen in hearing impairment accompanying cochlear sensory disorders. The hearing loss progresses over 10–20 years to also involve outer hair cells, producing a profound sensorineural hearing loss with absent ABRs and OAEs. Affected family members do not have evidence of other cranial or peripheral neuropathies. There was a marked improvement of auditory functions in three affected family members studied after cochlear implantation with return of electrically evoked auditory brainstem responses (EABRs), auditory temporal processes, and speech recognition. These findings are compatible with a distal auditory nerve disorder affecting one or all of the components in the auditory periphery including terminal auditory nerve dendrites, inner hair cells, and the synapses between inner hair cells and auditory nerve. There is relative sparing of auditory ganglion cells and their axons.     

Patterns of auditory processing and articulation deficits in academically deficient juvenile delinquents

Auditory processing deficits and articulation disorders were studied in a group of male juvenile delinquents. Significant auditory processing deficits were frequently observed and were significantly related to underachievement in reading, spelling, and arithmetic. In addition, articulation disorders were present in over 60% of the delinquent subjects. The results are interpreted to indicate that the evaluation of speech capabilities and auditory processing skills should be an integral part of treatment programs for delinquent populations. The importance of early intervention through identification and treatment of speech and language disorders in the early school period is supported.     

Short-term rehabilitation of patients with posttraumatic otolith disorders by auditory feedback training: a pilot study

In a prospective, non-randomized pilot study, two groups of patients with dizziness for more than one year due to posttraumatic otolith disorders had been investigated. They were treated by a one-day vestibular rehabilitation training with/without auditory feedback. It could be shown that auditory feedback training for a limited period of time can reduce significantly trunk sway compared to those patients who did vestibular exercises alone without auditory feedback. This audiofeedback-based therapy seems to be a promising tool in the vestibular rehabilitation and in treating patients with otolith disorders in particular. Long-term effects cannot yet be assessed with the present data of our series.     

Audiovestibular neuropathy in an immunocompetent man with cryptococcal meningitis

IntroductionCryptococcus spp. is a fungus responsible for 600,000 deaths per year worldwide, mainly in immunosuppressed subjects. However, 20% of cases occur in immunocompetent subjects. Neuropathic disorders involving the auditory nerve have been reported, but vestibular disorders have never been described in detail. We report the case of an immunocompetent man, who presented audiovestibular disorders leading to a diagnosis of cryptococcal meningitis.Case reportA 39-year-old man was referred for balance disorders and right sensorineural hearing loss. He presented right vestibulo-saccular impairment and bilateral absence of auditory brainstem responses. Brain MRI was suggestive of cryptococcal meningitis. A cystic lesion in the right flocculus compressed the vestibulocochlear nerve. During monthly follow-up, pure tone audiometry gradually improved and speech audiometry in silence returned to normal. Partial resynchronization of the auditory afferent pathways was observed only on the contralateral side to vestibulocochlear nerve compression, while complete recovery of saccular function was observed.DiscussionCryptococcal meningitis in immunocompetent subjects may be accompanied by lesions of the auditory and vestibular afferent pathways. Recovery of hearing and balance was observed in response to medical treatment and early vestibular rehabilitation.     

A combined functional in vivo measure for primary and secondary auditory cortices

Auditory evoked magnetic fields are reliable physiological in vivo markers of activity generated in auditory cortices. In recent years, several components of auditory evoked fields have been demonstrated with specific topographies within the auditory cortex in man. Their differential elicitation and analyses has rendered the discrimination of neural activities in primary vs. secondary auditory cortical fields possible. This in vivo measure may be of interest in a number of (neuro)psychiatric and neuropsychological disorders with central auditory deficits, in which in vivo anatomical measures do not allow a clear distinction of primary vs. secondary auditory cortex involvement. To help better understand the pathophysiology of such disorders, we developed and introduce a combined measure of steady-state field (SSR) and the N1 component of the transient evoked field. The acoustic stimulus for this paradigm consists of a 500-ms tone burst with 39-Hz amplitude modulation of the carrier frequency. This combined stimulation allows assessment of both auditory cortex components in one brief examination to be well tolerated by patients. We examined the source locations of SSR and N1 component with separate classical stimulation and combined stimulation within-session in healthy volunteer subjects. We demonstrate here that the distinct sources of steady-state (primary auditory cortex) and N1 (secondary auditory cortex) responses can be reliably measured without significant spatial distortion with this combined stimulation paradigm.     

Auditory processing,acoustic reflex and phonological expression

It is thought that a close relationship exists between auditory processing, the acoustic reflex and speech.AimA retrospective study to evaluate these three aspects in children with and without phonological disorders and seek any relationship among them.Material Methods46 children were enrolled: 24 had normal speech abilities and 22 had phonological disorders. All children underwent auditory processing and acoustic reflex threshold testing.DesignCross-sectional contemporary.ResultsAuditory processing and acoustic reflex thresholds were abnormal in all children with phonological disorders. This was not the case in children with normal speech development.ConclusionChanges in the auditory processing and acoustic reflex thresholds are closely related to speech difficulties.     

Auditory evoked potentials as measures of plasticity in humans.

There is increasing evidence from animal studies for plasticity of auditory function. This has prompted research to determine whether such plastic changes occur in adults and children with hearing disorders. Behavioural measures such as speech perception scores do show improvements after hearing aid fitting and cochlear implantation. Several studies have also shown changes in cortical auditory evoked potentials after cochlear implantation and after auditory training. These studies indicate that improvements in speech perception ability are associated with changes in the central auditory system, particularly at the cortical level.     

Peripheral, central and psychic deafness: diagnosis difficulties in case of autism child

The population ofchildren seen in the Georges Vacola day hospital, opened 20 years, suffer from serious personality disorders and from, hearing deficit. Speech and language disorders were present in every case. However. autism seems to be less prominent. The dtlfficulties in communicate are associated with problems of memory comprehension and hearing deficit. Many of the autistic children have associated deafness. The importance of central and functional deafness is highlighted. Deficits of mechanisms indispensable to the recognition, discrimination, structuralization, memorization of auditory stimuli are discussed. Another study including 500 autistic children showed that 15% of these children aged 11 to 13 years presented with auditory disorders.