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PubMed2006

Auditory cortical responses in patients with cochlear implants.

Currently, the most commonly used electrophysiological tests for cochlear implant evaluation are Averaged Electrical Voltages (AEV), Electrical Advisory Brainstem Responses (EABR) and Neural Response Telemetry (NRT). The present paper focuses on the study of acoustic auditory cortical responses, or slow vertex responses, which are not widely used due to the difficulty in recording, especially in young children. Aims of this study were validation of slow vertex responses and their possible applications in monitoring postimplant results, particularly restoration of hearing and auditory maturation. In practice, the use of tone-bursts, also through hearing aids or cochlear implants, as in slow vertex responses, allows many more frequencies to be investigated and louder intensities to be reached than with other tests based on a click as stimulus. Study design focused on latencies of N1 and P2 slow vertex response peaks in cochlear implants. The study population comprised 45 implant recipients (aged 2 to 70 years), divided into 5 different homogeneous groups according to chronological age, age at onset of deafness, and age at implantation. For each subject, slow vertex responses and free-field auditory responses (PTAS) were recorded for tone-bursts at 500 and 2000 Hz before cochlear implant surgery (using hearing aid amplification) and during scheduled sessions at 3rd and 12th month after implant activation. Results showed that N1 and P2 latencies decreased in all groups starting from 3rd through 12th month after activation. Subjects implanted before school age or at least before age 8 yrs showed the widest latency changes. All subjects showed a reduction in the gap between subjective thresholds (obtained with free field auditory responses) and objective thresholds (obtained with slow vertex responses), obtained in presurgery stage and after cochlear implant. In conclusion, a natural evolution of neurophysiological cortical activities of the auditory pathway, over time, was found especially in young children with prelingual deafness and implanted in preschool age. Cochlear implantation appears to provide hearing restoration, demonstrated by the sharp reduction of the gap between subjective free field auditory responses and slow vertex responses threshold obtained with hearing aids vs. cochlear implant.

Acoustic Stimulation↗
PubMed1990

Alterations of brain stem auditory evoked potentials in hypothermia.

Brain stem auditory evoked potentials (BAEPs) were studied as a criterion for evaluating hypothermic effects on the brainstem in rats. Eleven adult male Long-Evans rats were cooled slowly from 37 degrees C to 25 degrees C by an ice pad. BAEPs were recorded at intervals of every 1 degree C of change, and both central and peripheral acoustic conductions were assessed. As the body temperature decreased, latencies significantly increased, with the most prominent effect at the higher brainstem level. Interpeak latencies were prolonged also, while the reverse occurred with warming. These data agree with previous studies in other animals and men. However, during analysis of the effects of hypothermia on the brain stem auditory pathway, it was shown that these hypothermic effects were equally distributed throughout the whole pathway in the present study, rather than being emphatic in the proximal portion only. Greater prolongation of latencies in the proximal portion was caused by a cumulative effect from the distal peaks. Recovery was attained completely after rewarming and subsequent survival. Under extreme hypothermia, BAEPs disappeared gradually with apnea and cardiac arrest; however, resuscitation and rewarming saved the rats. In addition to wishing to make conventional observations, the present study sought to recognize the section of the acoustic pathway most sensitive to hypothermic effects and interpret the outcome after hypothermia treatment.

Animals↗
PubMed1983

Progressive bulbar paralysis in childhood: a case report.

The case of a progressive bulbar paresis in a nine and a half year old child is reported. The first symptoms were present at birth; however, the subsequent evolution was very low. Lesion of the motor nuclei of the V, VII, IX, XII, cranial nerves was evident on electromyographic investigation. Damage to the acoustic brain stem pathway was documented by the brain stem evoked potentials although audiometry was normal. No other neuronal systems or districts appeared to be damaged. The case suggests Fazio-Londe disease, although the involvement (albeit partial) of the auditory pathways recalls Van Laere syndrome. This supports the view that motor neuron disease in infancy is not an autonomous entity but a variant in a wide spectrum of progressive neuronal diseases.

Audiometry↗
PubMed1986

Neural generators of the brain-stem auditory evoked potentials (BAEPs) in the rhesus monkey.

Brain-stem auditory evoked potentials (BAEPs) were recorded from rhesus monkeys in response to click stimuli. The BAEPs in the monkey have only 4 major peaks, while 5 major peaks can be identified in the human BAEP. The responses from electrodes placed at the vertex and the mastoid recorded either differentially or separately using non-cephalic references were compared to concomitant recordings from the auditory nerve, the cochlear nucleus, and the inferior colliculus, including the lateral lemniscus and the brachium of the inferior colliculus. It was found that the response from the intracranial portion of the auditory nerve lags behind the far-field response recorded from the mastoid by about 0.2 msec. The major component of the potentials recorded from the lateral lemniscus appeared with a latency that was close to that of the fourth peak in the BAEP. Deafferentation of the inferior colliculus resulted in only small changes in the BAEP, indicating that the contributions to the BAEP from the inferior colliculus and more central structures of the ascending auditory pathway are insignificant. It is concluded that the main reason for the difference between the human BAEP and the BAEP in the rhesus monkey is the smaller size of the monkey's head and the resulting shorter auditory nerve. The result is that the auditory nerve in the monkey only generates one peak in the far-field response, while in man the auditory nerve gives rise to both of the two earliest peaks in the BAEP; thus, the BAEP in man has 5 peaks while that in the monkey has only 4 peaks.

Animals↗
PubMed2026

Utility of hearing aid use on neurocognitive functions and auditory processing: A systematic review.

PURPOSE: Hearing loss not only affects the peripheral auditory system but also leads to changes in central auditory pathways and neurocognitive skills. The use of hearing aids has shown potential benefits in mitigating the adverse effects of hearing loss. Earlier literature showed various studies assessing the impact of hearing aid use on cognitive functions and auditory processing, a comprehensive review of the existing literature is warranted. Existing literature showed heterogeneous outcomes among studies investigated the effect of Hearing aid use in combating the adverse effects of hearing loss on neurocognitive functions and auditory processing. METHOD: Databases including PubMed, SciELO, Cochrane Library, PsycINFO, Web of Science, and Index Copernicus were searched (2005-2025) using English keywords on hearing aid effects on neurocognition and auditory processing in individuals with hearing loss. Studies on effect of hearing aid use on neurocognition and auditory processing were included, while those involving cochlear implant users or other neurological disorders unrelated to hearing loss were excluded. Titles, authors and publication years were examined, and duplicates were removed. RESULTS: Total of 61 research papers were found on specific area and were included in the present review. Findings of these 61 articles have been analysed and are reported in this article. The outcome of the present study showed usefulness of hearing aid use on neurocognitive functions and auditory processing. CONCLUSION: The present literature review emphasized the importance of early rehabilitation through hearing aid use to alleviate the adverse effects of hearing loss on neurocognitive function and auditory processing.

Humans↗
PubMed1997

Audiovestibular and neuropsychological outcome of adults who had recovered from childhood bacterial meningitis.

A sample of 22 subjects was studied from a population of adults who had suffered from bacterial meningitis in childhood. Audiovestibular, oculomotor and neuropsychological investigations were performed and quality of life was assessed. An age-matched control group of 20 subjects was recruited. In the meningitis group, nine subjects had abnormal pure tone audiograms. One was previously undiagnosed and a progression was found in four. There was an overrepresentation of subclinical vestibular pathology (6 out of 9 (67%)) in this group. Audiovestibular test results showed a peripheral pattern and oculomotor tests were normal. The quality of life scores of those with hearing loss were significantly higher than those in the control group. Neuropsychological tests of brain dysfunction were abnormal in six out of 22 (27%) who had recovered from meningitis. The prevalence of such dysfunctions was not related to audiovestibular disorder. The quality of life scores of those with brain dysfunctions were similar to those of the control group. The findings of reduced auditory memory and tone level perception in four out of 22 (18%), suggest that lesions of central auditory pathways may follow from bacterial meningitis. The results support the idea that inner ear damage is the major cause of hearing loss after bacterial meningitis. Despite the absence of brainstem involvement, central nervous system lesions with disturbed auditory processing and language functions can be of significance. The high frequency of discrete brain dysfunctions indicate that a thorough neuropsychological investigation is required after bacterial meningitis.

Adult↗
PubMed2001

Fos imaging reveals differential neuronal activation of areas of rat temporal cortex by novel and familiar sounds.

To provide information about the possible regions involved in auditory recognition memory, this study employed an imaging technique that has proved valuable in the study of visual recognition memory. The technique was used to image populations of neurons that are differentially activated by novel and familiar auditory stimuli, thereby paralleling previous studies of visual familiarity discrimination. Differences evoked by novel and familiar sounds in the activation of neurons were measured in different parts of the rat auditory pathway by immunohistochemistry for the protein product (Fos) of the immediate early gene c-fos. Significantly higher counts of stained neuronal nuclei (266 +/- 21/mm2) were evoked by novel than by familiar sounds (192 +/- 17/mm2) in the auditory association cortex (area Te3; AudA). No such significant differences were found for the inferior colliculus, primary auditory cortex, postrhinal cortex, perirhinal cortex (PRH), entorhinal cortex, amygdala or hippocampus. These findings are discussed in relation to the results of lesion studies and what is known of areas involved in familiarity discrimination for visual stimuli. Differential activation is produced by novel and familiar individual stimuli in sensory association cortex for both auditory and visual stimuli, whereas the PRH is differentially activated by visual but not auditory stimuli. It is suggested that this latter difference is related to the nature of the particular auditory and visual stimuli used.

Acoustic Stimulation↗
PubMedDate not supplied

Cochlear implantation after acoustic tumour resection in neurofibromatosis type 2: impact of intra- and postoperative neural response telemetry monitoring.

The present paper reports about a 16-year-old male with neurofibromatosis type 2 (NF-2) of the Wishart type with bilateral deafness who had undergone cochlear implantation after resection of the acoustic neuroma (AN) of the same side. Neural response telemetry (NRT) recordings are essential in those patients during cochlear implantation where no stapedial reflexes can be electrically elicited due to the resection of the AN. In the present case, amplitude growth function and a type II pattern of the NRT waveforms could be well established. The comparison of the N(1) response intra-operatively and after 2 years showed a decline in latency by 50% and an increase in absolute amplitude by 10 times at the same current level of electrical stimulation. This improved auditory nerve transduction suggested a change to a 'faster' encoding strategy to improve speech understanding. The change from SPEAK to ACE 18 months after the operation led to an increase in the open-set sentence recognition test from 52 to 88%. Thus, NRT recordings monitor the intra-operative success of electrode placement and help to assess the integrity of the auditory pathway. Moreover, they can reliably be used in programming the speech processor postoperatively as objective tool. In patients with NF-2, the restoration of hearing can be successfully achieved in several ways. The indications for hearing implants (auditory brain stem and cochlear implants) should be carefully considered with respect to the remaining, functional integrity of the auditory nerve and the technical possibilities to monitor the success of these procedures.

Action Potentials↗
PubMed1992

Auditory brain-stem response in zitter rats with genetic spongiform encephalopathy.

Zitter rats with genetic spongiform encephalopathy and hypomyelination developed an abnormal auditory brain-stem response (ABR) before the appearance of spongy lesions in the central nervous system (CNS). The ABR abnormalities were characterized by a dual peak of wave I, with a longer latency than in normal rats, and decreased or absent waves III and IV. Hypomyelination in both peripheral and central nerves may have been responsible for these abnormalities. The slow negative wave became wide and obscure with aging. These changes accompanied age-dependent progression of spongy changes in the CNS. These findings suggest that at least two mechanisms, one involving hypomyelination and the other causing spongy lesions, are responsible for the brain-stem auditory pathway dysfunction in zitter rats.

Action Potentials↗
PubMed1990

Tinnitus with normal hearing sensitivity: extended high-frequency audiometry and auditory-nerve brain-stem-evoked responses.

Extended high-frequency (HF) audiometry and auditory-nerve brain-stem-evoked responses (ABR) were carried out on two groups of subjects with normal hearing sensitivity. The experimental group comprised 17 subjects with tinnitus, while the control group consisted of age- and sex-matched subjects, not suffering from tinnitus. The aim of the study was to determine whether extended HF audiometry or ABR might reveal significant differences between these two groups of subjects with normal hearing sensitivity. In addition, the characteristics of tinnitus in subjects with normal audiograms were discussed. The results of extended HF audiometry showed no significant differences between the subjects with and without tinnitus. The ABR parameters considered were also within normal limits bilaterally. Based on the methods employed in this study, tinnitus in normal listeners does not appear to reflect appreciable damage in the cochlea or in the brain-stem auditory pathways. The authors present some suggestions for future research.

Adult↗
PubMed1992

Functional/metabolic modulation of the brain stem lesions caused by 1,3-dinitrobenzene in the rat.

To determine whether neuronal activity plays a role in the localisation of brain stem lesions in 1,3-dinitrobenzene intoxication we produced asymmetrical changes in auditory input by rupturing the left tympanic membrane in Fischer rats. This raised the auditory threshold on that side from 57-63 dB to 104-122 dB. It also decreased glucose utilisation in the ipsilateral cochlear nucleus and significantly increased utilisation in the contralateral nucleus, resulting in a relative deficit of 72 +/- 6%. Similarly, tympanic membrane rupture led to decreased glucose utilisation in the contralateral and increased utilisation in the ipsilateral inferior colliculus. Additional exposure to "white noise" prevented the decrease in glucose utilisation in the contralateral inferior colliculus. Dosing with dinitrobenzene (10 mg/kg in 4 doses over 48 hr) to otherwise normal rats produces symmetrical vasculonecrotic lesions in these regions, but in animals with left tympanic membrane rupture the severity of morphological changes in the ipsilateral cochlear nucleus and the contralateral inferior colliculus were substantially reduced. Additional exposure to "white noise" increased the degree of damage in the ipsilateral cochlear nucleus and contralateral inferior colliculus. These findings indicate that altered auditory function in rats, with its associated metabolic consequences exercises a significant role in the development of brain stem damage in auditory pathways following dinitrobenzene intoxication.

Acoustic Stimulation↗
PubMed1991

Auditory nerve of the normal and jaundiced rat. I. Spontaneous discharge rate and cochlear nerve histology.

Hyperbilirubinemia is a major problem in neonatal intensive care. Hearing impairment is one of its sequelae. Although lesions of the central auditory pathways are known to be associated with this disorder in both humans and homozygous Gunn rats, the presence of cochler pathology is still controversial. The purpose of this study was to examine the functional integrity of the peripheral auditory system in the Gunn rat. The Gunn rat is a mutant of the Wistar strain with congenital deficiency of the liver enzyme uridine diphosphoglucuronyl transferase which is essential for bilirubin conjugation. This deficiency is inherited as an autosomal recessive trait, with the homozygous animals (jj) showing evidence of bilirubin encephalopathy. The heterozygotes (Jj) have 50% enzyme deficiency and are not jaundiced. The Long-Evans rat served as a control. The approach was to study the discharge characteristics fo single auditory nerve fibers using standard procedures in a closed and calibrated sound system. Various response measurements which would reveal pathological processes in the cochlea were analyzed. In this study, spontaneous discharge rate distribution and interspike interval statistics derived from Gunn rat auditory nerve recordings were found to be within the normal range, and cochlear nerve histology showed no evidence of neuropathy.

Action Potentials↗
PubMed1980

Clinical considerations in the interpretation of auditory brainstem response audiometry.

Auditory brainstem response (ABR) audiometry which monitors the electrical activity of the auditory nerve and brainstem nuclei, has provided a new technique in the diagnosis of neurological dysfunction and peripheral hearing deficits. Brainstem potentials consist of seven waves, each separated in latency by approximately one millisecond and each representing successively higher order neuron activity of the auditory pathway. The criteria used for ABR interpretation are based primarily on the latency of individual were peaks and their interpeak latencies. Due to its consistency and stability, the fifth wave has been considered prominent in the interpretation of auditory threshold sensitivity. Unfortunately, Wave V latency-intensity function may be affected by extrinsic and intrinsic variables. Consequently, in order to establish diagnostic criteria that are comparable, the elimination and/or control of these variables must be examined. Therefore, the purpose of this paper is to report the effects of various pathological and nonpathological conditions which contribute to difference in ABR audiometry interpretation.

Acoustic Stimulation↗
PubMed1998

Vestibular evoked myogenic potentials in patients with acoustic neuromas.

BACKGROUND: To diagnose acoustic neuromas (ANs), the auditory brainstem response test and the caloric test have been used in addition to magnetic resonance imaging. The auditory brainstem response and the caloric tests mainly reflect functions of the auditory pathway, ie, the cochlear nerve and the superior vestibular nerve, respectively. Because the vestibular evoked myogenic potential (VEMP) has been thought to originate in the inferior vestibular nerve, we hypothesized that the VEMP could provide different information from the auditory brainstem response and the caloric test and that it could be helpful in diagnosing ANs. In other words, we hypothesized that the VEMP could provide information concerning inferior vestibular nerve involvement in patients with ANs. OBJECTIVE: To find out if the VEMP could be useful in classifying ANs according to the involved nerves. DESIGN: We reviewed preoperative clinical tests, including VEMPs, in 21 patients (8 men, 13 women) with ANs confirmed surgically and histopathologically, comparing them with VEMPs in 8 normal subjects (5 men, 3 women). RESULTS: Whereas the first positive-negative peak of the VEMP, P13-N23, was ipsilaterally present on stimulation of the unaffected side in all patients with ANs and both sides in all normal subjects, it was absent on the affected side in 15 patients (71%) and significantly decreased in amplitude in 2 patients (9%). Thus, 17 (80%) of the 21 patients showed abnormal VEMPs. Three patients had abnormal VEMPs although they had normal caloric responses. Three patients had abnormal caloric responses although they had normal VEMPs. CONCLUSION: These results suggest that the VEMP could be useful for the diagnosis of AN, especially for classifying ANs according to the involved nerves.

Adult↗
PubMed1979

Early auditory evoked potentials (EAEP) in vertebral basilar insufficiency.

Stimulation with a short tone pip elicits an acoustic nerve compound action potential (I) and different waves (II--VII) in the inital 10 ms. Seven waves have been studied in 40 control subjects and five waves in 12 patients with vertebral-basilar insufficiency. Abnormalities of the different waves were observed at levels such as cochlea and/or acoustic nerve, medulla, caudal pons, rostral pons, and midbrain. The recording of early auditory evoked potentials (EAEP) is a noninvasive method of confirming impairment of the auditory pathway caused by a reduced vascular supply of vertebral and basilar arteries.

Acoustic Stimulation↗
PubMed2006

Minimization of cochlear implant stimulus artifact in cortical auditory evoked potentials.

OBJECTIVE: To compare two methods of minimizing cochlear implant artifact in cortical auditory evoked potential (CAEP) recordings. METHODS: Two experiments were conducted. In the first, we assessed the use of independent component analysis (ICA) as a pre-processing filter. In the second, we explored the use of an optimized differential reference (ODR) for minimizing artifacts. RESULTS: Both ICA and the ODR can minimize the artifact and allow measurement of CAEP responses. CONCLUSIONS: When using a large number of recording electrodes ICA can be used to minimize the implant artifact. When using a single electrode montage an optimized differential reference is adequate to minimize the artifact. SIGNIFICANCE: The use of an optimized differential reference could allow cortical evoked potentials to be used in routine clinical assessment of auditory pathway development in children and adults fit with cochlear implants.

Artifacts↗
PubMed2003

Neuronal populations and single cells representing learned auditory objects.

The neural representations associated with learned auditory behaviours, such as recognizing individuals based on their vocalizations, are not well described. Higher vertebrates learn to recognize complex conspecific vocalizations that comprise sequences of easily identified, naturally occurring auditory objects, which should facilitate the analysis of higher auditory pathways. Here we describe the first example of neurons selective for learned conspecific vocalizations in adult animals--in starlings that have been trained operantly to recognize conspecific songs. The neuronal population is found in a non-primary forebrain auditory region, exhibits increased responses to the set of learned songs compared with novel songs, and shows differential responses to categories of learned songs based on recognition training contingencies. Within the population, many cells respond highly selectively to a subset of specific motifs (acoustic objects) present only in the learned songs. Such neuronal selectivity may contribute to song-recognition behaviour, which in starlings is sensitive to motif identity. In this system, both top-down and bottom-up processes may modify the tuning properties of neurons during recognition learning, giving rise to plastic representations of behaviourally meaningful auditory objects.

Acoustic Stimulation↗
PubMed2001

Brainstem auditory-evoked potential examinations in diabetic patients.

Brainstem auditory-evoked potential (BAEP) examinations were performed in 15 patients with long-standing type-1 diabetes mellitus (DM). Cardiovascular reflex tests were applied for assessment of autonomic neuropathy. The aim of our investigation was to compare the BAEP results of this patient group with controls and to look for a possible correlation between the alteration of the auditory brainstem function and the cardiovascular autonomic neuropathy. Analysis of the latencies (waves I, II, III and V) and the inter-peak latencies (waves I-III and I-V) of BAEPs revealed a significant difference between diabetics and healthy controls. The amplitudes of waves I, III and V were definitely lower in comparison with those of healthy controls. A positive correlation was observed between the overall autonomic score and the latencies (waves III and V) and inter-peak latencies (waves I-III and I-V). These data support the hypothesis that long-standing DM and diabetic neuropathy might be related as a cause of certain dysfunctions of the central auditory pathways.

Adult↗