Recording Of Evoked Responses Research Articles

A funkcionális halláscsökkenés felismerése és komplex diagnosztikája

Hearing loss is a sensory impairment that impairs speech understanding, communication and therefore the quality of life. Sometimes the patient's perceived loss of function is exaggerated; subjective and objective test results are inconsistent, the subjectively reported hearing loss is more significant, and in these cases functional hearing loss is considered. Our aim was to collect and retrospectively analyze cases with the diagnosis of functional hearing loss, in order to draw conclusions about the characteristics of functional hearing loss, the signs and conditions that may be of attention and the consideration of appropriate rehabilitation. Subjective tests were performed with pure-tone auditory threshold, speech understanding and communication tests, which were compared with the results obtained with objective impedance measurements, stapedial reflex tests, otoacoustic emission measurements, and brainstem evoked response recordings. Imaging studies, psychologist, psychiatrist, neurologist, neurologist and other co-specialists were involved as needed. We excluded cases of deception deliberately intended to obtain financial or other benefits. Between 2007 and 2022, 19 patients were diagnosed with functional hearing loss. The majority (17 cases) were female, the complaints were prevalent at a young age (10-41 years); the average age in the study population was 19.6 years, and the majority of patients (13 cases) were children aged 10-17 years. No organic cause was found in 11 cases, and in the remaining cases no detectable organic abnormality explained the extent of the hearing loss experienced by the patient. The degree of functional hearing loss varied (35-120 dB), with an average of 60,2 dB. Recognizing and diagnosing functional hearing loss is very difficult and requires a complex series of tests and professional cooperation. Without recognition, the patient may receive unjustified, even harmful and financially burdensome care, which may lead to the deterioration of his condition. Orv Hetil. 2023; 164(8): 283-292.

Dépistage et diagnostic de la surdité chez le chien

Screening and diagnosis of deafness in dogs is based on Brainstem Auditory Evoked Response or BAER recording. Deafness is usually classified according to five criteria : determinism, onset, severity, symmetry, and anatomical-functional stage reached. In breeds at risk for hereditary deafness, with white or piebald robes (Dalmatian Dogo argentino, Bull terrier, Australian cattle dog, etc.) or merle (Border collie, Australian shepherd, etc.), screening of breeding animals and newborns should be encouraged to reduce the prevalence of deafness in these breeds. In dogs with acute deafness, hearing impairment should be confirmed by BAERs recording and lesions should be in-vestigated by medical imaging (CT-scan and/or magnetic resonance imaging). Acquired causes of deafness are nu-merous : inflammatory (especially otitis media), toxic (or ototoxicity), traumatic, degenerative (or presbycusis). In acute deafness in dogs, total bilateral deafness is most often irreversible.

A37 The role of technicians in ultrasound examinations of peripheral nerves and muscles

Objectives Neurophysiological technicians offer an important assistance to neurologists in performing electrodiagnostic (EDx) studies. Furthermore, in most places they are autonomous in carrying out nerve conduction studies, EEG and evoked response recordings. Methods Ultrasonography (US) of peripheral nerves and muscles is rather new diagnostic method. Therefore, the role of technicians in US examinations is not fully determined. Results Our laboratory for US of peripheral nerves and muscles has 7 years of experience performing routine clinical and research practice. In 2016 we performed 466 US examinations, mainly for evaluation of entrapment/compression neuropathies (carpal tunnel syndrome (CTS) - 108 (23%) and ulnar neuropathy at the elbow (UNE) - 204 (43%). Other pathologies include nerve traumas, tumors and inflammatory or hereditary neuropathies. Discussion The responsibility of neurophysiological technician is patients’ requests and appointments and correctly positioning the patient before the examination. Furthermore, technician is autonomous in performing well defined examinations (i.e. evaluation of the CTS and UNE) and must be able to take history and focused neurologic examination. Medical exam is finally prepared and interpreted by neurologist. To properly perform such studies technician should have thorough knowledge of human anatomy, physiology and pathophysiology of peripheral nerves and muscles. Skills should be obtained in scanning nerves transversely and longitudinally in order to select and capture the best image possible. Conclusions Although not fully determined, we believe the role of US technician is important. Not only to assist neurologist but also to independently perform well defined and simple examinations, which are typically the most common.

A flexible and inexpensive high-performance auditory evoked response recording system appropriate for research purposes.

Recording auditory evoked responses (AER) is done not only in hospitals and clinics worldwide to detect hearing impairments and estimate hearing thresholds, but also in research centers to understand and model the mechanisms involved in the process of hearing. This paper describes a high-performance, flexible, and inexpensive AER recording system. A full description of the hardware and software modules that compose the AER recording system is provided. The performance of this system was evaluated by conducting five experiments with both real and artificially synthesized auditory brainstem response and middle latency response signals at different intensity levels and stimulation rates. The results indicate that the flexibility of the described system is appropriate to record AER signals under several recording conditions. The AER recording system described in this article is a flexible and inexpensive high-performance AER recording system. This recording system also incorporates a platform through which users are allowed to implement advanced signal processing methods. Moreover, its manufacturing cost is significantly lower than that of other commercially available alternatives. These advantages may prove useful in many research applications in audiology.

Development of an ultra low noise, miniature signal conditioning device for vestibular evoked response recordings

BackgroundInner ear evoked potentials are small amplitude (<1 μVpk) signals that require a low noise signal acquisition protocol for successful extraction; an existing such technique is Electrocochleography (ECOG). A novel variant of ECOG called Electrovestibulography (EVestG) is currently investigated by our group, which captures vestibular responses to a whole body tilt. The objective is to design and implement a bio-signal amplifier optimized for ECOG and EVestG, which will be superior in noise performance compared to low noise, general purpose devices available commercially.MethodA high gain configuration is required (>85 dB) for such small signal recordings; thus, background power line interference (PLI) can have adverse effects. Active electrode shielding and driven-right-leg circuitry optimized for EVestG/ECOG recordings were investigated for PLI suppression. A parallel pre-amplifier design approach was investigated to realize low voltage, and current noise figures for the bio-signal amplifier.ResultsIn comparison to the currently used device, PLI is significantly suppressed by the designed prototype (by >20 dB in specific test scenarios), and the prototype amplifier generated noise was measured to be 4.8 nV/Hz @ 1 kHz (0.45 μVRMS with bandwidth 10 Hz-10 kHz), which is lower than the currently used device generated noise of 7.8 nV/Hz @ 1 kHz (0.76 μVRMS). A low noise (<1 nV/Hz) radio frequency interference filter was realized to minimize noise contribution from the pre-amplifier, while maintaining the required bandwidth in high impedance measurements. Validation of the prototype device was conducted for actual ECOG recordings on humans that showed an increase (p < 0.05) of ~5 dB in Signal-to-Noise ratio (SNR), and for EVestG recordings using a synthetic ear model that showed a ~4% improvement (p < 0.01) over the currently used amplifier.ConclusionThis paper presents the design and evaluation of an ultra-low noise and miniaturized bio-signal amplifier tailored for EVestG and ECOG. The increase in SNR for the implemented amplifier will reduce variability associated with bio-features extracted from such recordings; hence sensitivity and specificity measures associated with disease classification are expected to increase. Furthermore, immunity to PLI has enabled EVestG and ECOG recordings to be carried out in a non-shielded clinical environment.

Congenital deafness in Jack Russell terriers: Prevalence and association with phenotype

Congenital hereditary sensorineural deafness is the most common form of deafness in dogs. The objectives of this study were to determine a reliable measure of the prevalence of deafness in Jack Russell terriers, an affected breed, and associations between deafness and phenotypic characteristics. Brainstem auditory evoked response recordings and phenotypic parameters (coat color, coat texture, sex, eye color, sire and dam hearing status) were recorded for 1009 Jack Russell terriers. The prevalence of unilateral and bilateral deafness was 3.57% and 0.50%, respectively, lower by a factor of three to four than in earlier reports based on smaller and closely related kindreds. Significant association with deafness was identified with white coat color and parental hearing status, but not with sex or coat type. Lack of significant sex or coat type associations and the significant association with white coat color are consistent with previous reports. In conclusion the prevalence of deafness in Jack Russell terriers is lower than initially reported. Deafness was associated with white coat color and parental hearing status. The association with parental hearing status supports this form of deafness being a heritable trait in the breed and the association with white coat color supports an inheritance linked to pigmentation genes.

Audiovestibular findings in patients with deafness caused by a mitochondrial susceptibility mutation and precipitated by an inherited nuclear mutation or aminoglycosides.

To characterize the audiological and vestibular changes associated with a mitochondrial DNA mutation in an Arab-Israeli family and in other families with mitochondrial predisposition to aminoglycoside-induced hearing loss. Evaluation of audiological (pure tone thresholds, speech reception thresholds, speech discrimination, tympanometry, acoustic reflex thresholds, tone decay, and auditory brain-stem evoked response recording) and vestibular (complete history, physical examination, and 2-channel electronystagmography) systems. In 5 patients, structural evaluation of the inner ear was done by magnetic resonance imaging. Fifteen members of an Arab-Israeli family, and 1 Chinese woman with the same mitochondrial DNA mutation who experienced hearing loss after short-term exposure to streptomycin. Most of the patients had a profound hearing loss due to cochlear involvement. The hearing loss usually was not accompanied by notable peripheral vestibular dysfunction. In the patient with severe hearing loss after exposure to aminoglycoside, the vestibular function was completely normal. In most of the Arab-Israeli patients with congenital deafness, the vestibular system function was normal, in contrast to the frequency of vestibular abnormality among deaf children, which was described in the literature. This may be related to genetic predisposition to aminoglycoside-induced deafness.

Rhythmic and patterned neuronal firing in visual cortex.

We present evidence from multi-electrode recordings that the stimulus driven activity in a region of monkey visual cortex displays synchronous, oscillatory behaviour with temporally changing patterns of firing. The spatial-temporal patterns are dependent on cortical layer and on visual stimulus, 'build up and die down' with a period of 70-100 msec, and cannot be factorized into separate spatial and temporal components. This finding supports neural network models which explicitly incorporate spatial-temporal structure, ruling against a purely spatial code for information processing. The new type of analysis presented here is also suitable for direct on-line interactive analysis during multi-electrode recording experiments. Further, it could be modified for use in human EEG or evoked response recordings.

Fast decrement with stimulus repetition in ERPs generated by neuronal systems involving somatosensory SI and SII cortices: Electric and magnetic evoked response recordings in humans

The effect of stimulus repetition (short trains of stimuli with 1-s inter-stimulus intervals and 15-s inter-train intervals) on both electric and magnetic evoked responses were studied in four subjects. In addition to the later N140 and P300 deflections in electric potentials, a distinct and immediate amplitude decrement was obtained also for the earlier P50 and P100 deflections. The magnetic evoked responses also demonstrated the amplitude decrement for 50 ms (M50) and 100 ms (M100) latency deflections. The time-course and degree of amplitude decrement of the M100 magnetic response corresponded especially well to those of P100 electric deflections. The results thus show the rate effect on electric and magnetic responses at 50 and 100 ms latencies, and further suggest that the electric and magnetic responses, reflecting the activation of somatosensory SI and SII cortical areas at these latecies, respectively, are generated by related neuronal mechanisms.

The auditory P300 event—related potential: An objective marker of the encephalopathy of chronic liver disease

Recently many variants of electroencephalogram-evoked responses have been studied as potential diagnostic aids in the detection and evaluation of hepatic encephalopathy. This study assesses the value of the auditory P300 event-related potential--a slow component of the auditory evoked response--as a tool in this field. Twenty-one nonencephalopathic and 12 encephalopathic (grade 1/2) cirrhotic patients and 26 controls were assessed clinically and psychometrically. Electroencephalogram spectral analysis and visual evoked response recordings were also conducted. An auditory P300 wave was elicited using the standard two-tone discrimination paradigm. The latency and amplitude of this wave were measured. The latency of the P300 was found to be significantly increased in the encephalopathic patients compared with both nonencephalopathic cirrhotic and control groups (p less than 0.05). Amplitude of the wave was decreased in both nonencephalopathic and encephalopathic patients, but this was not statistically significant. This study suggests that the latency of the P300 is a good marker of grades 1 and 2 clinical hepatic encephalopathy. The delays in the P300 latency may indicate that encephalopathic patients have a deterioration of their stimulus evaluation abilities.

Effects of Stimulus Intensity on Direct Recordings of Eighth Nerve Auditory Evoked Responses

Effects of auditory stimulus intensity on auditory nerve and brainstem evoked potential patterns recorded simultaneously from the scalp and directly from the eighth nerve were compared for an anesthetized patient undergoing surgery for macrovascular decompression. Replicable robust potentials were readily obtained from a recording electrode on the eighth nerve less than half a second after as few as 15 stimulations. Less robust and less readable evoked potential patterns were obtained from scalp recordings after 30 seconds and about 900 stimulations. It was observed in the direct auditory evoked response (DAER) that there is a systematic decrease in peak latencies with each 10 dB increase in stimulus intensity between 60 and 90 dB nHL. Also, with each 10 dB increase in stimulus intensity there is an increase in amplitude of the DAER action potential between 70 and 90 dB nHL but not between 60 and 70 dB.

Laryngeal brain stem evoked response.

Sensory stimuli to the larynx evoke a laryngeal adductor reflex mediated by the brain stem via superior and recurrent laryngeal nerves. Aberrant laryngeal reflexes have been proposed to explain a number of poorly understood disorders, including "reflex apnea," idiopathic laryngospasm, and sudden infant death syndrome. The purpose of the present study was to evaluate far field brain stem recordings following stimulation of the superior laryngeal nerve to determine whether laryngeal brain stem response is a valid measure of laryngeal activity at the brain stem level. The nerve was stimulated electrically in adult cats, and the resultant laryngeal adductor response as well as far field brain stem activity was recorded. For the latter, six reproducible positive and five reproducible negative waves were obtained via posterior pharyngeal (+) and posterior cervical (-) recording electrodes. Response threshold and latencies were measured and evaluated as a function of stimulus parameters. Wave latencies corresponded closely to those reported in prior near and far field evoked response recordings.

Pseudotumor Cerebri (Benign Intracranial Hypertension): Etiopathogenesis, Diagnosis, And Management

Pseudotumor Cerebri (Benign Intracranial Hypertension): Etiopathogenesis, Diagnosis, And Management

An evaluation of different techniques for removing eye-blink artifact from visual evoked response recordings.

ABSTRACTThis investigation compared four methods used to control eye‐blink artifact in visual evoked response (VER) recordings using the augmenting‐reducing paradigm: rejecting trials containing blinks, presenting the stimuli through closed eyelids, and two different techniques for subtracting a proportion of the averaged electro‐oculogram (FOG) from the averaged VER. The two subtraction procedures differed in the way in which they estimated the amount of EOG to be subtracted and in the case with which they could be applied. Twenty normal, female subjects were exposed to a series of four different intensity light flashes twice with eyes open and once with eyes closed. Blinking was monitored by recording the EOG and EEG was recorded from three midline electrodes. The results indicated that the two subtraction techniques were very similar. They effectively removed ocular artifact and produced corrected VERs that showed high retest stability. Presenting the flashes through closed lids yielded idiosyncratic data, and rejecting trials contaminated by blinks was found to have limited utility with the VER paradigm used in the present study.

Pressure compliance of the optic nerve head in low tension glaucoma.

Twenty eyes of 10 healthy subjects, 11 eyes of seven patients with low tension glaucoma, and three eyes of three patients with ischaemic optic neuropathy were investigated. Visual evoked responses were recorded under stepwise artificially increased intraocular pressures. The results of the visual evoked response recording (pressure compliance test) allow a clear distinction to be made between healthy subjects, patients with low tension glaucoma, and patients with ischaemic optic neuropathy. In the groups investigated a lack of autoregulation of the optic nerve head circulation was found in patients with low tension glaucoma only. Patients with anterior ischaemic optic neuropathy showed the same pressure compliance behaviour as healthy subjects. The methods used here seem to provide a practicable clinical tool in the differential diagnosis of low tension glaucoma.

Evoked response “forward‐masking” functions in hearing‐impaired chinchillas

Previous research in psychophysics has shown that the time course of recovery from forward masking is prolonged in listeners with sensorineural hearing loss (Nelson and Turner, 1980). In order to evaluate the physiological basis for the change in the time course of forward masking, evoked response recordings were obtained from the inferior colliculus of the chinchilla both before and after noise induced hearing loss. Evoked response “forward‐masking” functions were obtained by measuring the masker level required to produce a 50% reduction in the response to a probe tone (re: probe response alone) which followed the masker at various time intervals (2 to 100 ms). The time course of “forward masking” was estimated by fitting a time constant to the data. Animals were exposed to a pure tone that produced either 30–50 dB of asymptotic threshold shift or 25–30 dB of permanent threshold shift. The time constants fit to the “forward‐masking” function were found to be prolonged in the region of hearing loss. In general there was a strong correlation between the time constant of recovery from “forward masking” and hearing loss. The implications of these results will be discussed. [Work supported by NIH 5‐R01‐NS16761‐06 and NIOSH 1‐R01‐OH00364.]

Pediatric applications of serial auditory brainstem and middle-latency evoked response recordings

Serial auditory brainstem (ABR) and middle-latency (AMR) response recordings were made for 12 children (8 male, 4 female) ranging in age from 2 weeks to 10 years. A total of 40 ABR and 32 AMR assessments were carried out at bedside in varied hospital environments, including a pediatric intensive care unit (ICU), a neonatal ICU and an operating room. Clinical entities were distributed as follows: acute, severe head injury (5), hydrocephalus (2), meningomyelocele (2), hyperbilirubinemia (1), ototoxic drug overdose (1), severe developmental delay (1). Auditory evoked responses were applied in monitoring peripheral and central auditory system status, and contributed to medical, surgical and audiologic management. Abnormalities of the ABR were reversed in some children, such as those with hydrocephalus, with medical or surgical therapy. In other cases, such as a hyperbilirubinemic child, a marked ABR abnormality apparently reversed spontaneously. We present five cases to illustrate diverse applications of serial auditory evoked response measures in children.

Electrocochleography (ECochG) and brain stem evoked response recordings (BSER) in the diagnosis of acoustic neuromas.

Evaluation of the auditory evoked responses has hitherto been the most important otoneurological method for early diagnosis of acoustic neuromas. ECochG enables to recognize serious damage to the first neurone. Criteria are: increased latency of the action potential (N1) and a low amplitude of the action potential relative to a high amplitude of the microphonic potential. BSER is a more sensitive indicator for functional deficiency in the first neurone, especially by evaluating interaural differences of the interpeak intervals (IPI) I-V and I-III. Problems arising when wave I cannot be clearly detected can be overcome by combining ECochG and BSER and evaluating the latency N1-V or perhaps in a better way by applying derivation of BSER between promontory and vertex. In 24 of 25 patients with indistinctly defined wave I in the standard recording, evaluation was possible in promontory BSER.

Ethanol-induced modification of sensory evoked potentials recorded from the caudate nucleus, substantia nigra, hypothalamus, and pineal

Modifications of the averaged sensory acoustic-evoked response (AAER) were examined following intraperitoneal injection of ethanol (1.67 g/kg). Changes in the evoked responses were correlated with blood alcohol concentration. Evoked field potentials from freely behaving rats previously implanted with stainless-steel semimicroelectrodes stereotaxieally were recorded simultaneously from the head of the caudate nucleus, substantia nigra, ventromedial hypothalamus, and pineal. Following ethanol administration, all four regions exhibited a general pattern of initial evoked response suppression (decreased component amplitudes) followed by gradual recovery in which the magnitude of suppression was directly related to the blood ethanol concentration. However, whereas more than 90% of the evoked response recordings from the caudate (P 2 and N 2 components) demonstrated significant amplitude decreases at maximum alcohol levels, fewer than 35% of recordings obtained from the substantia nigra exhibited such decreases. Moreover, the absolute magnitude of amplitude attenuation of the evoked responses was markedly greater in the caudate than in the substantia nigra. The responses recorded from the hypothalamus and pineal exhibited a similar pattern of suppression which was distinct from that recorded from the caudate and substantia nigra. The recovery profile of individual evoked response components (P 2, N 2, and p 2) as compared to alcohol levels was also observed to vary between the different brain areas examined. These results demonstrate a heterogeneous physiological response to acute ethanol exposure in four distinct brain regions mediating motor and neuroendocrine functions.

Coincidence eye position device with applications in clinical psychophysics, eye-position training and visual evoked response recording.

Coincidence eye position device with applications in clinical psychophysics, eye-position training and visual evoked response recording.