Auditory measures in clinically depressed individuals. II. Auditory evoked potentials and behavioral speech tests

This is the second paper in a series of two papers comparing auditory measures in depressed and non-depressed individuals. In this paper, we describe the auditory brainstem responses (ABRs), auditory late responses (ALRs) and behavioral speech measures obtained from the same set of 36 individuals as in our previous paper. No changes were made to the inclusion criteria or subject classification. The results indicated a significantly larger amplitude growth with increase in intensity for ABR peak V and ALR peak N1P2 in the unmedicated group compared to the normal group. The unmedicated group performed less favorably on most behavioral speech tests administered compared to the control group, but the difference was significant only in the left ear for the Low Predictability Sentence List of the R-SPIN (Revised-Speech Perception in Noise) test. The mean test scores of the medicated group were closer to the scores of the control group.     

Auditory measures in clinically depressed individuals. II. Auditory evoked potentials and behavioral speech tests

This is the second paper in a series of two papers comparing auditory measures in depressed and non-depressed individuals. In this paper, we describe the auditory brainstem responses (ABRs), auditory late responses (ALRs) and behavioral speech measures obtained from the same set of 36 individuals as in our previous paper. No changes were made to the inclusion criteria or subject classification. The results indicated a significantly larger amplitude growth with increase in intensity for ABR peak V and ALR peak N1P2 in the unmedicated group compared to the normal group. The unmedicated group performed less favorably on most behavioral speech tests administered compared to the control group, but the difference was significant only in the left ear for the Low Predictability Sentence List of the R-SPIN (Revised-Speech Perception in Noise) test. The mean test scores of the medicated group were closer to the scores of the control group.     

Auditory evoked potentials

Auditory evoked potentials (AEPs) have become an integral part of the current otologic/audiologic test battery. With these techniques, synchronous neural activity can be examined from the peripheral end organ of hearing up to the cortical structures responsible for audition. The clinical applications of AEPs range from their use as an indicator of auditory sensitivity in patients who either cannot or will not respond in a conventional behavioral test situation to their use in the diagnosis and monitoring of various otologic and neurologic disorders. As such, measurement of AEPs allows the clinician a unique glimpse of the auditory system.     

Intraoperative electrically evoked vestibular potentials in humans.

Electrically evoked short latency vestibular potentials were recorded in 9 patients during vestibular neurectomy. Patients were operated on because of intractable Meniere's disease. The VIIIth cranial nerve was exposed through a limited retrosigmoidal approach; the vestibular nerve was contacted in the cerebello-pontine angle with a bipolar platinum-iridium electrode and stimulated with biphasic current pulses (100 microseconds/phase, 0.75-1 mA p-p, 20/s). The responses were recorded over 12.8 ms between a forehead and an ipsilateral ear lobe electrode. Each recording consisted of 2 x 1,000 averaged responses. A systematically reproducible vertex-negative potential occurring at a latency of approximately 2 ms and having an amplitude of approximately 0.5 microV was recorded in all patients. This vertex-negative potential disappeared after selective vestibular neurectomy proximal to the stimulation site. Simultaneous continuous acoustic masking did not affect the response and no facial nerve response was observed on the facial nerve monitoring. These features strongly suggest that the characteristic vertex-negative potential constitutes a specifically evoked response of the vestibular system. Electrophysiological monitoring of the sectioning of the vestibular nerve during operation is one possible clinical application of intraoperative recording of electrically evoked vestibular potentials.     

Auditory brain-stem evoked potentials in Bell's palsy

In an attempt to assess objectively the integrity of the auditory pathways in patients suffering from Bell's palsy, an audiometric evaluation was performed and auditory brain-stem evoked potentials (ABEP) were obtained from 24 patients within the first week from the onset of facial weakness. Despite negative audiometric findings, significant ABEP abnormalities (greater than 2.5 SDs) were observed for 25% of the sample. In each case the ABEP deviation suggested prolonged brain-stem conduction time; for some patients the aberration was only apparent with an increased stimulus repetition rate. The ABEP measures were found to be independent of the side or severity of the paralysis, the acoustic reflex, or reported dysacusis. The ABEP was of no value in predicting recovery of facial muscle function. It is suggested that the facial paralysis may be only the overt manifestation of a generalized pathologic condition.     

Auditory brainstem evoked potentials in sudden deafness

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 53 adult subjects suffering from sudden deafness at the time of examination. The onset of sudden deafness was up to three years prior to the study. ABEP were recorded in response to 75 dBHL clicks presented at rates of 10/sec and 40/sec. ABEP peak latencies as well as interpeak latency differences, and also the effect of increasing stimulus rate, were determined for each patient and compared with the clinical symptoms. The psychoacoustic and ABEP detection thresholds were also compared. A highly significant correlation was observed between ABEP detection threshold and the psychoacoustically determined hearing threshold, and the differences between them were found to be insignificant. The results of this study indicate a central component in sudden deafness. This impairment manifests itself in abnormal effects of increasing stimulus rate on ABEP, and may be related to reduced central synaptic efficacy.     

Auditory evoked potentials in premature and full-term infants

Accurate information about type, degree, and configuration of hearing loss are necessary for successful audiological early interventions. Auditory brainstem response with tone burst stimuli (TB ABR) and auditory steady-state response (ASSR) exams provide this information.AimTo analyze the clinical applicability of TB ABR and ASSR at 2 kHz in infants, comparing responses in full-term and premature neonates.Material and MethodThe study was cross-sectional, clinical and experimental. Subjects consisted of 17 premature infants and 19 full-term infants. TB ABR and ASSR exams at 2000 Hz were done during natural sleep.ResultsThe electrophysiological minimum response obtained with TB ABR was 32.4 dBnHL (52.4 dBSPL); the ASSR minimum was 13.8 dBHL (26.4 dBSPL). The exams required 21.1 min and 22 min, respectively. Premature and full-term infant responses showed no statistically significant differences, except for auditory steady-state response duration.ConclusionsBoth exams have clinical applicability at 2 kHz in infants, with 20 min of duration, on average. In general, there are no differences between premature and full-term individuals.     

Auditory brainstem evoked potentials in asymptomatic lead-exposed subjects

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 29 adults and children, accidentally exposed to lead through food until approximately a year prior to this study. ABEP were recorded in response to 75 dBHL clicks presented at rates of 10/sec. and 55/sec. Average values were calculated for peak latency and for interpeak latency differences. Average values of the effect of increasing stimulus rate were calculated as well. Similar values were calculated for normative child and adult control groups. IPLD(I-III) showed the most significant and recurring results, with longer intervals in lead-exposed children compared with their control group. Increasing stimulus rate, on the other hand, affected the adult lead-exposed subjects more than the children. These results may imply an impairment of the peripheral portion of the auditory system with axonal and myelin involvement. ABEP is suggested as a sensitive detector of subclinical lead exposure effects on the nervous system.     

Auditory distortion products measured with averaged auditory evoked potentials.

The purpose of this investigation was to describe the properties of averaged auditory evoked potential distortion products (AEP-DPs) in guinea pigs. This study provided a step toward developing a clinical index of nonlinear processing of auditory signals and supplied a baseline for studies evaluating the effect of cochlear damage on AEP-DPs. The amplitude of the AEP-DPs was evaluated as a function of f2/f1 ratio (1.12-1.52) and primary frequency (500 Hz-2000 Hz). The amplitude of the AEP cubic difference tone (AEP-CDT) increased with increasing f2/f1 ratio for the 500-Hz f1 primary and remained constant for the 800-Hz and 1700-Hz f1 primaries. The AEP-CDT generated by the 1100-Hz and 1400-Hz f1 primaries was maximum for the middle f2/f1 ratios (1.22, 1.32, and 1.42). The AEP-CDT could not be distinguished from the noise floor for the 2000-Hz f1 primary. The AEP difference tone (AEP-DT) was larger and more frequently identified than the AEP-CDT. The amplitude of the AEP-DT decreased with an increase in f2/f1 ratio. The decrease was more pronounced for low-frequency f1 primaries than for high-frequency f1 primaries.     

Auditory evoked potentials from cortex and various subcortical centers

Summary The auditory system possesses connections to many different levels of the central nervous system.To secure some information that might be fitted into a future model, providing a better understanding of the underlying phenomena, AEP were recorded from the scalp, various cortical fields, and various subcortical structures during stereotaxic neurosurgical interventions.There is no doubt that vertex-mastoid registrations reveal non-specific components of the AEP, which can also be detected in recordings from subcortical structures.Latencies differed widely between responses obtained from the various structures, the shortest being that from the medial geniculate body.The authors further discussed the thalamo-cortical relationship of the CNV.

---

Zusammenfassung Das Hörsystem ist eines der wichtigsten Sinnessysteme. Es ermöglicht durch seine zahlreichen Verbindungen zu allen funktionellen Niveaus des Zentralnervensystems einschließlich des Rückenmarks die kürzeste Reaktionszeit auf einen Sinnesreiz. Der Sonomotorreflex spielt mit eine Rolle, indem er die Muskulatur über das schnelle ₁-System in Bereitschaft versetzt.Phylogenetisch und entwicklungsgeschichtlich wird die Bedeutung des akustischen Systems durch die Tatsache unterstrichen, daß es für Tiere in freier Wildbahn die wichtigste Warneinrichtung darstellt.Der Versuch, unspezifische, akustisch evozierte Potentiale (AEP) bei Skalpableitung als myogenen Artefakt abzutun, führte zur Entdeckung des Sonomotorreflexes und zu der Erkenntnis, daß eine schnelle myogene Komponente von der langsameren cerebralen in der Vertex-Mastoid-Ableitung unterschieden werden muß.Um einen Beitrag zur Elektrophysiologie des akustischen Systems zu leisten, wurde begonnen AEP mit Subperiostalnadelelektroden, mit durch das stereotaktische Bohrloch eingeführten flexiblen AgAgCI-Cortexelektroden von verschiedenen Rindenfeldern, und mit Tiefenelektroden von vielen thalamischen Kernen (einschließlich des Geniculatum mediale) und verschiedenen anderen subcorticalen Strukturen (Ammonshorn-Mandelkern-Komplex, Fornix, vordere Commissur) abzuleiten. Solche Gelegenheiten bieten sich bei den elektrophysiologischen Kontrollen während stereotaktischer Hirnoperationen am Menschen. Voraussetzung ist eine moderne elektronische Ausrüstung.Die Latenzen der unspezifischen Komponenten der AEP in den verschiedenen Strukturen sind sehr unterschiedlich. Auch die Form variiert über verschiedenen Rindenfeldern, läßt aber bei entsprechender Verstärkung Gemeinsamkeiten mit den vom Vertex-Mastoid abgeleiteten AEP erkennen.Die im Geniculatum mediale erstmals am Menschen bestimmte Latenz des Deflexionsbeginnes des spezifischen AEP beträgt etwa 7 msec.Es werden auch Untersuchungen der thalamo-corticalen Beziehungen der Erwartungswelle oder der kontingenten negativen Variation, sowie des motorischen Bereitschaftspotentials oder der Intentionswelle vorgenommen, wobei paarweise Clicks in irregulären Intervallen angewandt werden.Auf die mögliche Bedeutung des ersteren Phänomens für eine eventuelle objektive Sprachaudiometrie wird hingewiesen.

---

---

Investigations supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung.     

Auditory evoked potentials in patients with dementia of the Alzheimer type

Dementia of the Alzheimer type (DAT) disrupts the function of the central auditory nervous system as a result of temporal lobe pathology. Auditory brain stem response (ABR) and middle latency responses (MLR) were studied in a group of patients with DAT to determine whether a correlate of dementia existed in these electrophysiological potentials. Comparison of absolute and interwave latencies on ABR, and absolute latency and amplitude of the MLR in patients with DAT and normal aged controls showed no significant differences between groups for any measure. Further, no relationship with degree of dementia or temporal lobe involvement, as assessed through dichotic speech recognition studies, and auditory evoked potentials could be demonstrated. It was concluded that the temporal lobe atrophy and hypometabolism seen in DAT is not generally sufficient to disrupt the generating of ABR and MLR potentials; however, slow cortical and cognitive evoked potentials may be more sensitive to central auditory nervous system impairment in DAT.     

Vestibular evoked myogenic potentials in humans: a review

The human vestibule has preserved an ancestral sound sensitivity and it has been suggested that a reflex could originate from this property, thus inducing cervical muscle microcontractions secondary to strong acoustic stimulations. This reflex is assumed to originate in the saccule, the afferent pathways being either the vestibulocochlear nerve or the inferior vestibular nerve, and the efferent pathways the vestibulospinal tract. Averaging these muscular responses allows vestibular evoked myogenic potentials (VEMPs) to be obtained. The responses consist of two alternatively positive and negative successive waves (p13-n23, p33-n43). The characteristics of this reflex are defined in the literature as follows: it has been established that VEMP amplitude depends on muscular tension. All studies give concording evidence that in healthy subjects the first component of VEMP is more consistent than the second. Binaural stimulation is always responsible for responses of greater amplitude than those obtained from monaural stimulation. Following monaural stimulation, however, VEMPs are either of greater amplitude on the muscle ipsilateral to the stimulation or of the same amplitude on both muscles. There is consensus in the literature demonstrating that VEMP amplitude depends on stimulus intensity: the threshold of VEMP occurrence is clearly above auditory level but varies from one individual to the next. In the 1970s, recordings performed in cases of specific audiovestibular defects suggested that the reflex receptor could be the saccule. More recent studies suggest that the cochlea too could be involved in the response. Likewise, while a number of studies tend to demonstrate that VEMPs depend on vestibular integrity, others suggest that afferent pathways could be of both cohlear and vestibular origin. Finally, while it has been suggested that VEMP efferent pathways travel through the vestibulospinal tract, whether it is the lateral or the medial vestibulospinal tract that is concerned remains to be clarified. A few points regarding VEMP receptors and afferent and efferent pathways call for further investigation. They are inaccurate for use in routine vestibular examination. Once precise receptor localization and pathways are clarified, VEMP recording will provide both a straightforward non-invasive exploration of each vestibule independently and an attractive method by which to explore otolithic receptors and vestibulospinal pathways.     

Symmetry measures of vestibular evoked myogenic potentials using objective detection criteria.

Vestibular evoked myogenic potentials (VEMP) has been put forward as a test to evaluate the symmetry of saccular function. In the present study, the symmetry of VEMP was evaluated in 23 healthy subjects using automatic analysis. In response to binaural clicks with a stimulus repetition rate of 4/s all subjects revealed significant VEMP on both sides. The ipsilateral response to monaural clicks was similar to the response to binaural clicks. Although there were large interindividual variations in amplitude, there were only small variations in latency. VEMP measurements were also assessed using different stimulus rates. At the higher stimulus rates there was a decrease in the VEMP amplitude but there were only small changes in the latency. These findings might suggest that amplitude measures are more likely than latency measures to reveal small vestibular lesions.     

Auditory evoked potentials differ at 50 milliseconds in right- and left-handed listeners

Left-handed individuals show a 4 ms later Wave Pb in the 45-60 ms latency range of the auditory middle latency response (MLR) than right-handed individuals. Examination of auditory evoked potentials in fifteen right-handed and fifteen left-handed normal hearing adults showed that this difference was not evident in time periods earlier or later than 45-60 ms. The isolation of this latency difference to a specific time period suggests that the source or sources of Wave Pb may be an independent physiological index which correlates with hand preference.     

Auditory brainstem evoked potentials in insulin-dependent diabetics with and without peripheral neuropathy

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 33 insulin-dependent diabetes mellitus (IDDM) patients (17 with diabetic peripheral neuropathy and 16 without) as well as from 20 normals. Pure-tone audiometry, speech reception threshold and discrimination were also evaluated. Sub-clinical pure-tone threshold elevation was observed for IDDM patients with neuropathy. Pure-tone thresholds of IDDM patients without neuropathy were not significantly different from those of normals. ABEP abnormality (at 10/sec click rate) was observed in 31% of IDDM patients with neuropathy, rising to 44% when 55/sec click rate measures were included. Abnormalities included bilateral and symmetrical peak-latency prolongations for all waves, greater for the later waves, and prolongation of V-I and V-III interpeak latency differences, all at 10/sec, and only prolonged peak latency for I at increased rate. Abnormalities coincided with microangiopathy and peripheral neuropathy. The incidence of ABEP abnormality for IDDM patients without neuropathy was only 12%, unilateral and sporadic in nature. As a group, IDDM patients with neuropathy had significantly prolonged IV and V peak-latencies, compared with the normals, or with the IDDM patients without peripheral neuropathy. In contrast, IDDM patients without neuropathy resembled the normals in all respects. ABEP have proven useful in understanding the variety of pathologies underlying the clinical manifestation of diabetes.