Stapedius Muscle Reflex Research Articles

Indicators of the peripheral and central departments of the auditory analyzer according to the threshold tone audiometry and acoustic impedansometry data in participants of combat operations with a different course of sensoneural hearing loss

Aim: study of the characteristics of the acoustic stapedius-muscle reflex in conjunction with the data of threshold tone audiometry in combatants with different dynamics of the course of sensorineural hearing loss. Materials and methods: The characteristics acoustic stapedius-muscle reflex and the indicators of threshold tonal audiometry in combatants with different dynamics of sensorineural hearing loss were conducted. 60 military personnel were examined: group 1, with positive dynamics after treatment, group 2, in which progression sensorineural hearing loss took place, 30 people per group. Results and discussion: The study showed that patients who received combat acutrauma showed significant changes in the qualitative and quantitative characteristics of the acoustic stapedius-muscle reflex, which may indicate that they have disorders in the brainstem of the auditory analyzer. In patients with progressive sensorineural hearing loss, these disorders are more pronounced. Thus, they observed a significant (p<0.01) decrease in amplitude not only compared to the control, but also with the indicators of the group with positive dynamics. In addition, in the group with progressive course (group 2) there is a greater "dissociation" of acoustic stapediusmuscle reflex – a larger number of patients with no acoustic stapedius reflex, "asymmetric" acoustic stapediusmuscle reflex. When examining patients with combat acutrauma, we recommend examining both the peripheral (according to threshold tonal audiometry) and brainstem (according to acoustic stapedius-muscle reflex) department of the auditory system, which will not only identify disorders and prescribe the necessary treatment, but also assess the severity and predict the course of disorders in such patients. Therefore, acoustic stapedius-muscle reflex and its amplitude indicators should be used as diagnostic and prognostic criteria when conducting expert examinations of this category of patients. Conclusions: 1. In combat acutrauma there are violations both in the peripheral department of the auditory analyzer according to the threshold tonal audiometry, and in the central (brainstem) according to acoustic stapedius-muscle reflex. 2. In combat acutrauma there is a significant (p<0,01) decrease in the amplitude of acoustic stapediusmuscle reflex, more pronounced in fighters with progressive SNP. 3. "Asymmetry" of acoustic stapedius-muscle reflex, pronounced decrease in the amplitude of the acoustic reflex, "dissociation" of acoustic reflex indicators with the results of audiometric examination is not only a typical sign of hearing loss in fighters with acute trauma, but can be a prognostic marker and one of the criteria disorders in this category of patients. 4. When examining patients with combat acutrauma, it is advisable to study the characteristics of acoustic stapedius-muscle reflex.

The evaluation of the sense of hearing in patients with carotid artery stenosis within the extracranial segments

Stenosis of arteries that supplies blood to the brain is one of the main causes of ischemic stroke which is the third most common cause of deaths in Europe. Atherosclerosis of carotid and vertebral arteries is responsible for 20% of the ischemic stroke cases. Stenosis may be either asymptomatic or manifested with typical neurological symptoms including motor and sensory disturbances as well as disturbances in vision and speech. However, discrete non-specific symptoms of ischemia, including headaches and vertigo, tinnitus and hearing loss, are also quite common. These symptoms may be indicative of a clinically significant stenosis of carotid and vertebral arteries, particularly within the internal carotid artery region, as well as of a risk of ischemic stroke. To date, research reports were unable to provide exact explanation of correlations between impaired hearing and the stenosis of carotid and vertebral arteries. Despite this, numerous articles list these symptoms as one of the first non-specific symptoms of this disorder. The ischemic mechanism within the inner ear region may lead to early symptoms of atherosclerosis of large vessels. However, no evidence of relationship and no explanation could be provided with this regard. The objective of the study was to assess the effect of carotid and vertebral artery stenosis on the function of the hearing and equilibrium organ on the basis of diagnostic audiological examinations including pure-tone threshold audiometry, impedance audiometry, otoacoustic emission tests and brainstem auditory evoked potential tests. The study was conducted in 63 patients (32 males, 31 females) aged 45–75 years, presenting with carotid and vertebral artery stenosis and treated at the Vascular Surgery Clinic of the University Clinical Hospital in Wrocław. Patients were stratified into two subgroups according to their age (45–60 years, 61–75 years). Patients were also divided into subgroups according to the stenotic arteries and to the symptomatic/asymptomatic status of the disorder. All patients were homogeneous in terms of the degree of artery stenosis. The control group consisted of 32 healthy persons (14 males, 18 females) aged 48–75 years. Patients qualified to the control group reported no history of middle or inner ear disorders, disturbed hearing, vertigo and balance disorders, as well as cardiovascular diseases; they also presented with unremarkable ultrasound scans of the arteries. All patients were subjected to precise audiological examinations. Prior to being qualified for the study, patients were subjected to the assessment of arteries by means of Doppler ultrasonography. The hearing organ function was assessed by means of pure-tone threshold audiometry, impedance audiometry, otoacoustic emission tests and brainstem auditory evoked potential tests. Reduction of the flow through the carotid arteries causes problems in the organ of hearing; abnormalities are reported especially in tone threshold audiometry, examinations of the stapedius muscle reflexes and brainstem auditory evoked potentials, which prove the presence of receptive cochlear–extracochlear hearing damage. Disturbances of the organ of hearing have similar severity in stenosis of the internal carotid artery and vertebral artery. Abnormalities found in audiologic examinations in patients with carotid artery stenosis are not always explicitly clinically expressed in patients with hearing loss; we should consider diagnostics for carotid artery stenosis.

Identifying Otosclerosis with Aural Acoustical Tests of Absorbance, Group Delay, Acoustic Reflex Threshold, and Otoacoustic Emissions.

Otosclerosis is a progressive middle-ear disease that affects conductive transmission through the middle ear. Ear-canal acoustic tests may be useful in the diagnosis of conductive disorders. This study addressed the degree to which results from a battery of ear-canal tests, which include wideband reflectance, acoustic stapedius muscle reflex threshold (ASRT), and transient evoked otoacoustic emissions (TEOAEs), were effective in quantifying a risk of otosclerosis and in evaluating middle-ear function in ears after surgical intervention for otosclerosis. To evaluate the ability of the test battery to classify ears as normal or otosclerotic, measure the accuracy of reflectance in classifying ears as normal or otosclerotic, and evaluate the similarity of responses in normal ears compared with ears after surgical intervention for otosclerosis. A quasi-experimental cross-sectional study incorporating case control was used. Three groups were studied: one diagnosed with otosclerosis before corrective surgery, a group that received corrective surgery for otosclerosis, and a control group. The test groups included 23 ears (13 right and 10 left) with normal hearing from 16 participants (4 male and 12 female), 12 ears (7 right and 5 left) diagnosed with otosclerosis from 9 participants (3 male and 6 female), and 13 ears (4 right and 9 left) after surgical intervention from 10 participants (2 male and 8 female). Participants received audiometric evaluations and clinical immittance testing. Experimental tests performed included ASRT tests with wideband reference signal (0.25-8 kHz), reflectance tests (0.25-8 kHz), which were parameterized by absorbance and group delay at ambient pressure and at swept tympanometric pressures, and TEOAE tests using chirp stimuli (1-8 kHz). ASRTs were measured in ipsilateral and contralateral conditions using tonal and broadband noise activators. Experimental ASRT tests were based on the difference in wideband-absorbed sound power before and after presenting the activator. Diagnostic accuracy to classify ears as otosclerotic or normal was quantified by the area under the receiver operating characteristic curve (AUC) for univariate and multivariate reflectance tests. The multivariate predictor used a small number of input reflectance variables, each having a large AUC, in a principal components analysis to create independent variables and followed by a logistic regression procedure to classify the test ears. Relative to the results in normal ears, diagnosed otosclerosis ears more frequently showed absent TEOAEs and ASRTs, reduced ambient absorbance at 4 kHz, and a different pattern of tympanometric absorbance and group delay (absorbance increased at 2.8 kHz at the positive-pressure tail and decreased at 0.7-1 kHz at the peak pressure, whereas group delay decreased at positive and negative-pressure tails from 0.35-0.7 kHz, and at 2.8-4 kHz at positive-pressure tail). Using a multivariate predictor with three reflectance variables, tympanometric reflectance (AUC = 0.95) was more accurate than ambient reflectance (AUC = 0.88) in classifying ears as normal or otosclerotic. Reflectance provides a middle-ear test that is sensitive to classifying ears as otosclerotic or normal, which may be useful in clinical applications.

Aural Acoustic Stapedius-Muscle Reflex Threshold Procedures to Test Human Infants and Adults.

Power-based procedures are described to measure acoustic stapedius-muscle reflex threshold and supra-threshold responses in human adult and infant ears at frequencies from 0.2 to 8kHz. The stimulus set included five clicks in which four pulsed activators were placed between each pair of clicks, with each stimulus set separated from the next by 0.79s to allow for reflex decay. Each click response was used to detect the presence of reflex effects across frequency that were elicited by a pulsed broadband-noise or tonal activator in the ipsilateral or contralateral test ear. Acoustic reflex shifts were quantified in terms of the difference in absorbed sound power between the initial baseline click and the later four clicks in each set. Acoustic reflex shifts were measured over a 40-dB range of pulsed activators, and the acoustic reflex threshold was objectively calculated using a maximum 10 likelihood procedure. To illustrate the principles underlying these new reflex tests, reflex shifts in absorbed sound power and absorbance are presented for data acquired in an adult ear with normal hearing and in two infant ears in the initial and follow-up newborn hearing screening exams, one with normal hearing and the other with a conductive hearing loss. The use of absorbed sound power was helpful in classifying an acoustic reflex shift as present or absent. The resulting reflex tests are in use in a large study of wideband clinical diagnosis and monitoring of middle-ear and cochlear function in infant and adult ears.

Assessment of the Brainstem-Mediated Stapedius Muscle Reflex in Andean Children Living at High Altitudes.

Counter, S. Allen, Leo H. Buchanan, Fernando Ortega, Anthony B. Jacobs, and Göran Laurell. Assessment of the brainstem-mediated stapedius muscle reflex in Andean children living at high altitudes. High Alt Med Biol. 18:37-45, 2017.-This study examined the physiological thresholds, amplitude growth, and contraction duration of the acoustic stapedius reflex (ASR) in Andean children aged 2-17 years living at altitudes of 2850 m (Altitude I Group) and 3973 m (Altitude II Group) as part of a general medical assessment of the health status of the children. The brainstem-mediated ASR reveals the integrity of the neuronal components of the auditory reflex arc, including the cochlea receptors, eight cranial nerves, and brainstem neural projections to the cochlear nuclei, bilateral superior olivary nuclei, facial nerve nuclei, and facial nerve and its stapedius branch. Uncrossed (ipsilateral) and crossed (contralateral) ASR thresholds (ASRT), ASR amplitude growth (ASRG) function, and ASR muscle contraction duration (decay/fatigue) (ASRD) were measured noninvasively with 500, 1000 Hz and broadband (bandwidth = 125-4000 Hz) noise stimulus activators using a middle ear immittance system. Oxygen saturation (SaO2) level and heart rate were measured in a subsample of the study group. Statistical analyses revealed that the Altitude I and Altitude II groups had ASRT, ASRG function, and ASRD rates comparable to children at sea level and that the two groups were not significantly different for any of the ASR measures. No significant association was found between SaO2 or heart rate and ASRT, growth, and muscle fatigue rate. In conclusion, the assessment of the ASR in children in the high-altitude groups revealed normal function. Furthermore, the results indicate no adverse oto-physiological effects of altitude on the brainstem-mediated ASR at elevations between 2850 and 4000 m and suggest normal middle ear and auditory brainstem function.

Acoustic stapedius muscle reflex in mercury-exposed Andean children and adults

Acoustic stapedius muscle reflex in mercury-exposed Andean children and adults

Acoustic stapedius muscle reflex in mercury-exposed Andean children and adults

Conclusion: The results suggested mercury (Hg)-induced anomalies in the brainstem-mediated acoustic stapedius muscle reflex in children. Objectives: Hg exposure has been associated with hearing impairment and brainstem anomalies. Acoustic stapedius reflex (ASR) thresholds, growth functions, decay/adaptation times, and behavioral auditory thresholds were used to screen Andean children and adults for Hg-induced auditory brainstem and facial nerve impairment. Methods: Fifty-one participants, which included 22 children (aged 6–17 years) and 29 adults (aged 19–83 years) living in gold mining areas of Ecuador where Hg is widely used in amalgamation, were screened using ASR immittance procedures. Results: Mean blood mercury (HgB) level in the children was 15.6 μg/L (SD, 21.3; median, 7 μg/L; range, 2.0–89 μg/L), and in the adults 8.5 μg/L (SD, 7.1; median, 6 μg/L; range, 2.0–32 μg/L). Mean contralateral ASR thresholds (ASRT) for the screening frequency of 2000 Hz in the children (39 ears) was 92.9 dB HL (SD, 6.1; range, 80-105 dB HL), and in the adults (53 ears) 90.0 dB HL (SD, 6.4; range, 65-105 dB HL). The ASRT in the children increased significantly with HgB level (rho = 0.433; p = 0.008).

Assessment of auditory brainstem function in lead-exposed children using stapedius muscle reflexes

The purpose of this study was to investigate the neurological integrity and physiological status of the auditory brainstem tracts and nuclei in children with chronic lead (Pb) exposure using non-invasive acoustic stapedius reflex (ASR) measurements of afferent and efferent-neuromuscular auditory function. Following audiological examinations, uncrossed (ipsilateral) and crossed (contralateral) brainstem ASR responses were evoked by pure tone (500, 1000, and 2000 Hz), and broadband noise (bandwidth: 125–4000 Hz) stimulus activators. The ASR threshold (ASRT), amplitude growth, and decay/fatigue were measured by conventional clinical middle ear immittance methods in a group of Andean children (age range: 2–18 years) with a history of chronic environmental Pb exposure from occupational Pb glazing. Blood lead (PbB) levels of the study group (n = 117) ranged from 4.0 to 83.7 μg/dL with a mean PbB level of 33.5 μg/dL (SD: 23.6; median: 33.0: CDC III Classification). The PbB distribution data indicated that 77.8% (n = 91) of the children had PbB levels greater than the CDC action line of 10 μg/dL. Repeatable, normal ASRTs were elicited for ipsilateral (mean: ≤ 90 dB HL) and contralateral (mean: ≤ 97 dB HL) stimulation for each acoustic activator. Spearman Rho correlation analysis indicated no significant association between PbB level and ipsilateral or contralateral ASRT for any of the stimulus activators. The ASR amplitude growth results showed typical growth functions with no Pb-associated aberrations. No statistical association was found between ASR decay/adaptation (ASRD) and PbB level for any of the stimulus activators. The results of stapedius muscle reflex testing using several stimulus activators showed no significant relationship between PbB level and the physiological integrity of the auditory brainstem mediated ASR responses in children with chronic Pb exposure and elevated PbB levels.

WITHDRAWN: [Significance of Stapedius Muscle Reflex Measurement in Diagnosing Auditory Processing Disorders.

BACKGROUND: Stapedius muscle reflexes (SMR) are among the objective procedures which are used in the diagnostics of auditory processing disorders (APD). The significance of SRM for APD-diagnosis is open up to now. METHOD: Twenty-six children (8 - 10 years) with diagnosed APD and a control group of 17 children the same age were examined in order to determine whether differences with regard to the mean SMR (sine tones or band pass noise) exist between groups. In addition, differences between groups were investigated regarding the mean difference between the reflex thresholds for sine tones and the thresholds for band pass noises. RESULTS: Significant differences between groups existed in the mean value ipsilateral with 500 Hz, 1 kHz, 4 kHz and low bandpass noise as well as contralateral with 500 Hz. The contralateral measurements using sine tones (500 Hz, 1 kHz, 2 kHz and 4 kHz) showed reflex thresholds of about 100 dB only in the APD group. The results of the remaining types of stimulation showed a more or less distinctive area of overlap between the APD-group and the control group without the possibility of definite classification to a particular group. Group differences in the mean value with regard to the reflex thresholds for sine tones and the thresholds for band pass noises appeared only in low frequency stimuli. However, the area of overlap between the APD group and the control group in other frequencies was very large. CONCLUSION: Elevated thresholds measured in contralateral SMRs seem to support the assumption of APD. In contrast, the results of SMRs using ipsilateral measurements as well as low or high pass filtered noises contribute little toward diagnosing an APD. This applies identically to the difference between the reflex thresholds on sine tones and the thresholds on band-pass noises.

Brainstem mediation of the stapedius muscle reflex in hydranencephaly

Hydranencephaly is a rare condition in which the cerebral hemispheres are absent at birth and are replaced by membranous sacs in a cerebrospinal fluid-filled cranium. Surviving hydranencephalic patients have a functional brainstem and possible remnants of the cerebral cortex. This case report examines hearing function and the integrity of the brainstem mediated stapedius muscle reflex (SMR) in an adult with hydranencephaly, using middle ear impedance change measures. The brainstem mediated ipsilateral and cross-brainstem contralateral SMRs were elicited in the right ear at normal threshold levels for noise bands of 0.25–1.0, 1.0–4.0, and 0.25–4.0 kHz (broadband), and at the sinusoidal frequencies of 0.5, 1.0, and 2.0 kHz. The ipsilateral and contralateral SMR decay rates were normal. The growth in the SMR amplitude in response to noise and pure tone stimuli from threshold to saturation over a 15–20 dB range was normal and showed essentially sigmoidal curves. The normal ipsilateral and crossed brainstem contralateral electrophysiological SMR in this hydranencephalic patient demonstrated the preservation of peripheral hearing reception and functional brainstem auditory afferent and efferent tracts and nuclei in the absence of corticofugal influence.

Auditory prosthesis with automated voice muting using the stapedius muscle reflex

An auditory prosthesis includes a sound sensor that senses both ambient sounds and sounds uttered by the patient. The prosthesis includes a monitor that senses a physiological parameter indicative of the intensity of the sounds as perceived by the patient and/or the onset of a prospective speech episode during which the patient utters sounds. For example, the monitor may detect the activity of the stapedius muscle. This muscle contracts in the presence of subjectively perceived high level sounds or just prior to and during a speech episode. This parameter is used dynamically by the prosthesis to process the received sounds, for example, by changing the amplification level of these sounds dependent on the activity.

A look at neural integration in the human auditory system through the stapedius muscle reflex.

Ipsilateral and contralateral stapedius muscle contractions were studied as functions of the sound pressure level (SPL) and duration of 2-kHz tone bursts. The study complemented a preceding study in which temporal summation of stapedius muscle contractions produced by pairs of short tone bursts was determined and analyzed. The muscle contractions were determined indirectly by measuring changes in the acoustic impedance they produced at the tympanic membrane. The data for the stapedius muscle contraction as a function of tone-burst duration were derived from another study and analyzed in part with the help of the SPL functions obtained in the present study. According to the experimental results, the stapedius muscle contraction produced by contralateral stimulation follows a compressive power function paralleling both the cochlear output and loudness functions. The ipsilateral contraction follows an expansive power function. Mathematical analysis showed that the muscle tension due to contralateral stimulation increases with tone duration approximately according to the characteristic of a linear integrator having an exponentially decaying memory with a time constant that increases with SPL from approximately 200 to 370 msec. The simple relationship appears to be possible because of mutual cancellation of neural-processing characteristics preceding and following the temporal integration.

Auditory system: Peripheral nonlinearity and central additivity, as revealed in the human stapedius-muscle reflex.

Human stapedius-muscle contractions in response to 3-kHz, 20-msec tone bursts were determined indirectly by measuring the associated acoustic-impedance changes at the tympanic membrane with an acoustic bridge. The measurement was possible because the bridge practically eliminates the effect of the ear-canal air volume interposed between the tympanic membrane and the tip of the measuring tube. By using burst pairs, temporal additivity of the muscle responses was demonstrated both when the stimulus bursts were presented contralaterally to the measured impedance changes and when the first burst was presented ipsilaterally. The summation time constant was on the order of 200 msec, much longer than the twitch time constant of the muscle fibers. Therefore, the summation had to take place in a nucleus preceding the stapedius muscle. The magnitude of the muscle response obeyed a compressive function paralleling the loudness function up to sound pressure levels of at least 120 dB.

Auditory function at 14 years of age of very-low-birthweight children

The aim of the study was to determine audiological function at 14 years of age of very-low-birthweight (VLBW 1500g) children compared with a cohort of normal birthweight (NBW >2499g) children. Participants were consecutive surviving preterm children of birthweight <1000 g born between 1977 and 1982 (n=86) and of birthweight 1000 to 1500g born between 1980 and 1982 (n=124) and randomly selected NBW children born between 1981 and 1982 (n=60). Audiometric tests included pure tone audiometry, tympanometry, stapedius muscle reflexes, and measures of central auditory processing. Psychometric tests included measures of IQ, academic achievement, and behaviour. There were no significant differences in rates of hearing impairment, abnormal tympanograms, figure-ground problems, or digit recall between VLBW children and NBW control children. VLBW children had higher rates of some central auditory processing problems, which in turn were associated with poorer intellectual, academic, and behavioural progress.

Auditory function at 14 years of age of very‐low‐birthweight children

The aim of the study was to determine audiological function at 14 years of age of very-low-birthweight (VLBW < or = 1500 g) children compared with a cohort of normal birthweight (NBW > 2499 g) children. Participants were consecutive surviving preterm children of birthweight < 1000 g born between 1977 and 1982 (n=86) and of birthweight 1000 to 1500 g born between 1980 and 1982 (n=124) and randomly selected NBW children born between 1981 and 1982 (n=60). Audiometric tests included pure tone audiometry, tympanometry, stapedius muscle reflexes, and measures of central auditory processing. Psychometric tests included measures of IQ, academic achievement, and behaviour. There were no significant differences in rates of hearing impairment, abnormal tympanograms, figure-ground problems, or digit recall between VLBW children and NBW control children. VLBW children had higher rates of some central auditory processing problems, which in turn were associated with poorer intellectual, academic, and behavioural progress.

Ojective Intraoperative Method to Record Averaged Electromyographic Stapedius Muscle Reflexes in Cochlear Implant Patients: Metodo objetivo transoperatorio para el registro electromiográfico promediado de los reflejos del müAsculo estapedial en pacientes con implante coclear

We have developed a procedure to measure the averaged stapedius muscle reflex in response to electrical stimulation (AESR) with a cochlear implant. The AESR, as activated by ipsilateral stimulation with a cochlear implant, was investigated intra-operatively in a series of 12 children. After the cochlear implant was placed into the cochlea and secured by the surgeon, an electromyographic (EMG) needle electrode was gently placed into the stapedius muscle. During stimulation of the cochlear implant, the stapedius reflex was monitored visually (VESR) and as an averaged EMG response (AESR). Consistent AESRs were obtained in 7 of the 12 children. These measures provide a method to obtain stapedius muscle responses that may be helpful in the programming oi young children with cochlear implants. Comparative post-operative measures were also obtained, including behavioral threshold levels, behavioral comfort levels, and the contralateral stapedius reflex threshold (ESR) on selected electrodes.

Neural response telemetry with the nucleus CI24M cochlear implant.

To review our intraoperative and postoperative testing protocol for cochlear implant patients. This study describes the methodologies and applications of a new technique called neural response telemetry (NRT) for the Nucleus CI24M cochlear implant system. NRT uses radiofrequency telemetry technology to measure the action potentials of the auditory nerve. We have developed a specific protocol for intraoperative testing of the implant device before, during, and after implantation. This includes device integrity tests, visual detection of electrical stapedius muscle reflexes (VESR), and NRT. Our methodologies use the commercial software (Windows-based Diagnostic and Programming System [WIN-DPS] and NRT) for the Nucleus CI24M. We describe the details of our protocol used on all of the patients (14 adults and 14 children) who received CI24M implants at Mayo Clinic (Rochester, MN). Our protocol correlates the NRT threshold with the behavioral responses for each patient on at least four electrodes. From August 1, 1998, to December 31,1998, we completed electrode integrity tests, NRT, and VESR testing intraoperatively on 12 patients with the Nucleus CI24M. We have measured normal implant function on all 28 of our CI24M patients with one exception. One of our children had a device failure after approximately 4 months as a result of head trauma. We have also obtained NRT results from an additional 10 patients postoperatively. The measurement of device and electrode array function is quite simple with the CI24M software. These measurements can be obtained intraoperatively as well as postoperatively. We conclude that VESR and NRT measurements can be very helpful in programming for patients with cochlear implants, especially children, because they provides us with target settings for the speech processor.

Cochlear Implantation in Deaf Children

A cochlear implant (CI) is a hearing device introduced in the 1980s for profoundly deaf subjects who gained little or no benefit from powerful hearing aids. This device comprises an electrode array inserted in the cochlea, connected to an internal receiver, and an externally worn speech processor. The CI transforms acoustic signals into electrical currents which directly stimulate the auditory nerve. Since the early 1990s, cochlear implantation in children has been developing rapidly. Although it is still difficult to predict how a child will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, some recent papers and reports, and the results of the various Nijmegen cochlear implant studies, are reviewed. Issues about selection, examinations, surgery and the outcome are discussed. Overall, our results were comparable with those of other authors. It can be concluded that cochlear implantation is an effective treatment for postlingually deaf as well as prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

Effects of linear frequency modulated ramps on stapedius muscle reflex (SMR) in children

Thirty 6-year-old children with normal hearing, speech discrimination, and SMRs to tones and noise were given FM stimulation. A 2000-Hz tone was presented at 15 dB + SMR threshold until SMR decayed. The frequency was either modulated upward (to 40000 Hz) or downward (to 1000 Hz) in 100 ms for a series of intensity steps until a full contralateral SM contraction was recorded. Decay of the tonal SMR preceded FM testing at each step. The reciprocal to the 2000-Hz rising ramp was also employed and presented re the 4000-Hz tonal SMR. Ramps were filtered to equate intensity. All FM ramps induced a reactivation of the SMR. When equated at the percent of full contraction the 2000-Hz rising ramp had a larger dynamic range than either the falling or reciprocal conditions. The SMR waveform morphology varied with sound intensity. At high levels the SMR onset and offset was fast and the amplitude high, but as the sound intensity decreased onset and offset times increased and amplitudes reduced resulting in a broadening of the waveform.

High frequency audiometry and stapedius muscle reflex thresholds in juvenile diabetics.

Sixty-one juvenile, insulin-treated diabetics below 50 years of age with a duration of diabetes mellitus longer than 10 years underwent impedance audiometry with determination of stapedius reflex thresholds at 500 Hz, 1, 2, and 4 kHz, conventional pure tone and speech audiometry, and high-frequency audiometry up to 20 kHz. The results were compared with a normative material of non diabetic subjects selected after exactly the same criteria. No significant differences in hearing or stapedius reflex thresholds were found. Among half of the subjects there was a diabetic retinopathy. A comparison between those with and those without retinopathy did not reveal any significant difference in audiological findings. Even subjects with severe diabetic complications and almost life-long diabetes had normal hearing. Recent investigations on plasma-lipoids have discussed the possibility that insulin might prevent a premature ageing of hearing which has been reported by other authors. It is concluded that no statistical data exist that confirm a correlation between hearing impairment and diabetes.