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PubMedDate not supplied

The relaxation time of the stapedius reflex in dystrophia myotonica (Steinert).

Eight patients with dystrophia myotonica (Steinert) were studied. They all had myotonia and pathological EMG and in some cases other signs of the disease. The 50% relaxation times of the stapedius reflex were significantly prolonged compared with a control group of 40 healthy, young subjects with normal hearing and normal stapedius reflex thresholds. The relaxation times could be well quantified and had a low standard deviation from the mean in the control group. In the patient group as well as in the control group only slight differences in the relaxation times were found between the frequencies 500 and 2000 Hz and between the simultaneously measured ipsilateral and contralateral reflexes. It was concluded that measurement of the relaxation time of the stapedius reflex increases the diagnostic possibilities in patients with myotonia.

Adolescent↗
PubMedDate not supplied

Effect of crossed stapedius reflex on vibration of mallear handle in man.

The ear drum was made to vibrate using frequency-modulated sound pulses of 40 ms duration, and the vibration velocity of the tip of the mallear handle (umbo) was measured with laser vibrometry before and during stapedius muscle contractions (elicited by sound of 100 dB HL in the contralateral ear). The stapedius reflex caused: an attenuation of the mallear vibrations below 1 kHz, a slight enhancement of the vibrations between 300 Hz and 1,500 Hz. These effects of the stapedius reflex appear to be caused by an increased stiffness in the structures affecting the mallear vibrations.

Adult↗
PubMed1986

The stapedius reflex test studied with laboratory and commercial equipment in acoustic neurinomas.

Comparisons were made of contralateral stapedius reflex recordings obtained by means of two different electroacoustic impedance devices, the commercial Grason-Stadler 1723 (G-S 1723) impedance meter and a laboratory equipment, in patients with acoustic neurinoma. With the latter, acoustically elicited reflex responses were noted in 11 of the 21 tumour ears studied. The recordings with the G-S 1723 showed deflections indicating stapedius reflex responses in all 21 cases. Three of these deflections proved to be artefacts. The stapedius reflex threshold test indicated a retrocochlear lesion in all 21 pathological ears when the laboratory equipment was used. The G-S 1723 produced recordings indicating a cochlear lesion in two of these tumour ears. Furthermore, five of 15 normal contralateral ears were classified as having a retrocochlear lesion with the G-S 1723, as opposed to one with the laboratory equipment. The reflex decay test could be applied in 15 normal and six tumour ears. Only minor discrepancies in the degree of reflex decay were found between the two instruments. As the G-S 1723 displayed a low rate of detection for acoustic neurinomas (90%) and led to a large number of false-positive interpretations (33%), it is concluded that this instrument is less useful for diagnostic purposes than the laboratory equipment in differentiating between cochlear and retrocochlear lesions.

Acoustic Impedance Tests↗
PubMed1990

Dynamic range of the contralateral stapedius reflex in cochlear implant patients.

The dynamic range of the contralateral Stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 8 subjects supplied with a Vienna prosthesis. The study comprised patients fitted with intracochlear devices as well as patients with extracochlear devices. Sinusoidal bursts of 125, 500, 1,000 and 2,000 Hz were used as stimulation signals. Only in one patient was saturation of reflex amplitude observed. The dynamic range of the Stapedius reflex was defined either by the difference in stimulus level for reflex saturation or individual uncomfortable loudness level and reflex threshold. Two different methods were used, yielding values between 0.1 and 12 dB, with a median of 4 dB. The individual results were compared with individual psychoacoustic quantities, i.e. subjective dynamic range (difference between sensation threshold and uncomfortable loudness level) and residual dynamic range (difference between most comfortable loudness level and uncomfortable loudness level). The reflex dynamic range is located within the residual dynamic range of electrostimulation. Thus the Stapedius reflex dynamic range can be applied as a rough estimate of minimum residual dynamic range.

Acoustic Stimulation↗
PubMed1999

Outcomes after laser stapedotomy with and without preservation of the stapedius tendon.

Our goal was to investigate the postoperative differences in hearing between patients who had their stapedius tendon sacrificed and those whose stapedius tendon was preserved during laser stapes surgery for otosclerosis. To that end, we performed a retrospective review by mailing extensive questionnaires to patients who had been operated on between 1994 and 1997. We also performed routine and special audiometric testing to augment the subjective data. Seventy-nine of 124 questionnaires (64%) were returned. Of the respondents, 75 patients had undergone additional pre- and/or postoperative audiometric testing, including tests to evaluate "hearing in noise" and to determine the "uncomfortable loudness level" (dynamic range). We found no statistically significant differences between the two groups with respect to their subjective responses and their audiologic test results. The responses to the questionnaire indicated that in most cases, hearing was improved by stapes surgery. We conclude that the stapedius tendon should be preserved whenever possible during stapes surgery, provided that it does not jeopardize the exposure or outcome.

Adult↗
PubMed1992

Stapedius reflex in patients with an inner ear prosthesis.

The stapedius reflex elicited by electrical stimulation was investigated in 21 deaf individuals supplied with an inner ear prosthesis. All patients were implanted with the Vienna cochlear implant using intra or extracochlear electrodes. Analog stimulation with sinus bursts of various durations (25, 50, 100, 300, 500 ms) and frequencies (125, 500, 1000, 2000 Hz) was used. The time course of the contralateral acoustic reflex was monitored using a fast-response impedance meter. The stapedius reflex was observed in about half of the cases. Reflex threshold was observed at a stimulation level close to uncomfortable loudness. The time course in case of electrical stimulation differs in some aspects (rise time, onset) from acoustic stimulation in hearing individuals. Temporal integration of the stapedius reflex was observed also in case of electrostimulation through the cochlear implant.

Adolescent↗
PubMed1988

Stapedotomy with and without stapedius tendon preservation versus stapedectomy: long-term results.

Stapedectomy and stapedotomy are presently the techniques utilized in the surgical treatment of otosclerosis. The technique of choice at the ENT Department of the University of Verona has changed from stapedectomy to stapedotomy with and without stapedius tendon preservation. From January 1975 to December 1985, 805 ears were operated on for otosclerosis at our department. A statistical analysis has been performed on three groups of patients (stapedectomy, stapedotomy without and with stapedius tendon preservation) at short and long term. The results suggest that stapedotomy with stapedius tendon preservation should be the preferred surgery in the treatment of otosclerosis.

Adolescent↗
PubMed1980

[Stapedius-reflex-audiometry by measuring the threshold for the re-inforcement of a pre-existing reflex (author's transl)].

The possibilities for predicting the pure tone threshold on the basis of the acoustic stapedius reflex threshold are improved by using two stimuli, e.g., white noise and pure tone, or two pure tones according to Sesterhenn and Breuninger. The principle of the monaural loudness summation with regard to the stapedius reflex was systematically examined with the aim to obtain the best suited range for clinical use with a double tone stimulus. The following procedure proved to be the most reliable one for an objective audiometry: A distinct reflex is produced by a basic pure tone of 4 kHz, 10 dB above its reflex threshold. The tone to be examined (1 kHz) was added with a delay of 0.5 s. A 1 kHz tone 28 dB below the reflex threshold (median) produced a clear re-inforcement of the basic reflex. Objective extrapolation possibilities from stapedius reflex threshold to pure tone threshold are thereby improved.

Acoustic Impedance Tests↗
PubMed1995

[The time parameters of the stapedius reflex. The normal results].

The evaluation of the temporal characteristics of the acoustic stapedius reflex is one the fundamental aspects of the impedance audiometry, since significant biological information to be used as sensitive indicators of distinctive pathologies can be obtained. At the Audiology Service of the E.N.T. Department of Parma four parameters of the acoustic stapedius reflex have been studied (onset latency, latency at 10% of the maximum amplitude, rise time, offset latency) in a group of people having normal ears without previous otological problems, with the aim to establishing some rules. The equipment used is the Madsen Impedenzometro ZO 174 which enables to obtain an average among a desired number of reflex responses. The report shows the value of the four parameters of the stapedius reflex obtained from the study of 10 normoacusic patients totalling 20 ears. The resulting guidelines can make up the basis for further research in pathological cases with cochlear, neural and central lesions.

Acoustic Impedance Tests↗
PubMed1995

[Electrostimulation-induced stapedius reflex. Presentation of a standardized procedure and results of clinical studies].

The electro-tactile elicitation of the stapedius muscle reflex is well known but not used in clinical practice. Despite a complex reflex pathway in the brainstem, correlations between reflex parameters and neurological impairments are still possible. We have developed a method for eliciting the electro-tactile stapedius muscle reflex and automatic analysis of different reflex parameters by using an analog-digital converter and a personal computer-integrated signal analysis system. Clinical investigations were carried out with a group of 55 healthy persons (control group), 13 patients with central facial palsies, 51 patients with multiple sclerosis (MS group) and 24 patients with absent acoustic-stapedius muscle reflexes. Findings demonstrated that the latency between stimulus and beginning of the reflex (L1) was significantly longer in the MS group compared with the control group. The best parameter for dividing the MS group into groups with different disability scores was S, which was the parameter for the increase in the L1 growth curve at different stimulus levels. Reproduction of the parameter S in repeated tests with different locations of the stimulus-electrode was excellent.

Brain Damage, Chronic↗
PubMed1997

Intraoperative electrical stimulation of the stapedius reflex in children.

OBJECTIVE: To describe the use of intraoperative electrical stimulation on the stapedius reflex in children. SETTING: Hospital cochlear implantation center. PATIENTS AND METHODS: Eighteen children under the age of 10 years, who have undergone cochlear implantation, have been examined during surgery with the electrically elicited stapedius reflex in the monopolar stimulation mode. RESULTS: A stapedius reflex could visually be detected for all subjects. CONCLUSION: The responses serve to test the implant, provide guidance in avoiding overstimulation of the child when the device is switched on, and estimate the optimal C-levels.

Child↗
PubMed1969

The occurrence, structure and innervation of slow and twitch muscle fibres in the tensor tympani and stapedius of the cat.

1. The muscle fibres of the tensor tympani and stapedius of the cat have been examined in the light microscope in teased preparations after cholinesterase staining and in the electron microscope.2. In both muscles, two kinds of fibre have been found: those with an individual end-plate and those with multiple nerve terminals.3. The stapedius fibres with an end-plate have fibrils regularly separated from each other by sarcoplasmic reticulum, a straight Z line, transverse tubular T system elements regularly occurring at the junction of A and I bands, an M line, an extensive sole plate area, and numerous post-junctional sarcolemmal infoldings under the nerve terminal. This type of muscle fibre in the tensor tympani has all of these features except that the fibrils are not well separated from each other, T system elements are absent in some sarcomeres, and a typical M line is absent.4. Compared to the individually innervated fibres, the fibres with multiple endings have fibrils poorly separated from each other by sarcoplasmic reticulum, a jagged Z line, very few T system elements, a less extensive sole plate area, and essentially no folds under the nerve terminal. These fibres in both muscles have M lines.5. Muscle fibres have thus been found in both the tensor tympani and stapedius of the cat which conform in their innervation, the structure of their motor nerve endings, and their internal structure to many of the morphological characteristics which are exhibited by slow muscle fibres elsewhere.

Animals↗
PubMedDate not supplied

The role of the stapedius reflex in poststimulatory auditory fatigue.

The human ear is very resistant against noise-induced damage in the low frequency range. The aim of the present study was to investigate whether or not the stapedium reflex is of any importance for this resistance. Subjects with peripheral facial palsy (Bell's palsy) including unilateral stapedius muscle paralysis were exposed to several different levels of narrow band noise centered at 0.5 and 2.0 kHz. Temporary threshold shift (TTS) at 0.75 kHz was significantly higher in the affected than in the nonaffected ear after 0.5 kHz noise at and above 110 dB SPL. After the exposure with 2.0 kHz narrow band noise there was no difference in TTS at 3.0 kHz between the affected and nonaffected ear. It is concluded that the attenuation provided by the stapedius reflex reduces TTS after low frequency noise exposure. An implication is that the stapedius reflex also may have the function of protecting the ear from hearing damage caused by low frequency noise exposure.

Acoustic Stimulation↗
PubMedDate not supplied

Stapedius reflex in the monitoring of NaF treatment of subclinical otosclerosis.

Stapedius reflex testing was utilized to monitor the progression of subclinical otosclerosis and evaluate the efficacy of NaF treatment in stabilizing the disease process. The investigation was performed on 93 relatives of patients suffering with surgically confirmed otosclerosis. Subjects were divided into two groups. The first group was treated with NaF in doses ranging from 6 to 16 mg in relation to age. The treatment lasted two years. The second group served as control subjects. Before entering the research, all subjects presented reflex abnormalities represented by a partial or complete on-off effect in one or both ears. Changes in stapedius reflex morphology (from partial to complete on-off and from complete on-off to absence of the reflex) were evaluated at 1 and 2 years. The groups had not developed significant differences at 1 year. At 2 years, the incidence of stable stapedius reflex findings was 91.5% in the treated ears and 77% in the control group. The difference is significant (p less than 0.05) and indicates a stabilizing effect of NaF on the disease process.

Acoustic Impedance Tests↗
PubMed1984

A unique striated muscle: further morphological and x-ray microanalytical investigation of the stapedius muscle of the guinea pig using thin and thick cryosections.

Thin (130-200 nm) and thick (10-16 micrometers) cryosections of stapedius muscle of guinea pig were examined by X-ray microanalysis in the scanning- and scanning-transmission mode of electron microscopy. To further explore the unusual elemental composition of stapedius muscle and to evaluate previously used method of analysis of thick cryosections cut at -30 degrees C (Wróblewski et al., 1981), thin cryosections cut at -100 degrees C were investigated. The ultrastructural organisation of stapedius muscle with the centrally located nuclei and the mitochondria could be easily recognized in unstained thin cryosections. X-ray microanalytical investigations of thin sections revealed nearly the same elemental composition of single organelles as results obtained on defined areas in thick cryosections. Analysis of mitochondrial matrix. The elements appeared, however, at the same ratio (1:1). The P/Ca ratio was approximately 6:1 in the nuclei. Myofibrils presented low K and higher Ca concentrations. The levels of other elements (P. S. Cl) were close to those found in the quadriceps muscle of the guinea pig, rat, or human.

Animals↗
PubMed2000

Measurement of stapedius contraction during vocalization effort in patients after laryngectomy or tracheostomy.

The contraction of the stapedius muscle during the effort of vocalization was examined by measurement of acoustic compliance in subjects who had undergone laryngectomy or tracheostomy. No significant level of persistent compliance change was recorded in any of the subjects, indicating the absence of effective contraction of the stapedius during the vocalization effort. In two subjects who use an electrolarynx, although no significant compliance change resulted from the simple vocalization effort without the electrolarynx (no actual vocalized sound), a remarkable level of persistent compliance change was observed during the vocalization using the electrolarynx. These results seem to indicate that a simple vocalization effort without actual voice cannot elicit effective contraction of the middle ear muscles, and that sound generation during vocalization is essential for effective contraction of the middle ear muscles during vocalization, at least in some human subjects.

Aged↗
PubMed2002

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.

Acoustic Impedance Tests↗
PubMed1978

Effect of sensorineural hearing loss on acoustic stapedius reflex growth functions.

The growth function of the acoustic stapedius reflex was measured in subjects with normal hearing and sensorineural hearing loss of cochlear origin. The effects of age and magnitude of hearing loss were controlled. Activating stimuli were 500, 1000, and 2000 Hz tones and broadband noise. Stapedius muscle activity was inferred from acoustic impedance measures in the contralateral ear. The mean growth functions for tones were essentially linear in log-log plots with the rate of growth equal for the two groups. The mean growth function for the noise signal was curvilinear for the normal hearing groud had linear for the hearing loss group. Comparison of slope functions derived from the fitted data indicated that the rate of reflex growth for the noise signal, over a limited range above reflex threshold, is greater in ears with cochlear lesions than normal ears. For higher level noise signals, however, the rate of reflex growth is similar for normal and pathological ears. The effect of a cochlear lesion on the input-output function of the cochlea for both tonal and noise stimuli is to maintain the rate of reflex growth but shift the function along the intensity axis of a tonal signal and the response axis for a noise signal.

Acoustic Impedance Tests↗