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At least 163 records · Page 9Linked to original sources
PubMed1988

[Dynamic properties of the ipsilateral tactile-elicited stapedius muscle reflex in probands with normal hearing].

We tested 94 male and female persons with normal hearing. From these persons we elicited from the external ear canal the ipsilateral tactile stapedius muscle reflex and examined its dynamic properties. The electric stimulus consisted of a series of electric impulses of a duration of 30 msec lasting for 1 sec. The intensity ranged from 2.0-8.0 mA increasing in steps of 0.5 mA. Statistical evaluation showed a significant reflex dependence on stimulus intensity and sex of the volunteers but not on the volunteer's age. Starting with a stimulus intensity of 3.5 mA all tested persons showed good reflex response. The average latency between the start of the stimulus and the beginning of the reflex was 130-200 msec diminishing with growing stimulus intensity. The best parameters describing the dynamic properties of the reflex seem to be the latencies L 1 and L 3 at a stimulus intensity of 3.5 - 6.0 mA.

Brain Stem↗
PubMed1987

[Anatomical variations and anomalies of the musculus stapedius tendon. Study by scanning electron microscopy].

The authors used scanning electronic microscopy to investigate and define morphological characteristics of the musculus stapedius tendon: the opening through which the tendon protrudes at the eminentia pyramidalis and it can be found at its base. Fibers of the tendon may directly be attached to the bony surface of the stages or its prolongation of various forms and dimensions. In some cases the tendon fibrous bundles are more or less ossified. In one patient who was operate we found a congenital malformation manifested as absence of the tendon and deformation of the stapes. The tendon absence is found in 0.5% of cases.

Humans↗
PubMed1984

[Auditory-evoked brainstem potentials and stapedius muscle reflex: intersubject variability].

Like other workers, we found gender differences in auditory-evoked brainstem response latencies. For the time being, this intersubject variability remains unexplained. This difference was observed only for wave V latency, and delta I-V is longer in men than in women, whereas delta I-III is identical. The absence of functional differences in the lower portion of the auditory tract is confirmed by both auditory-evoked brainstem potentials and stapedius reflex latency. Wave V latency and the influence of technical and anatomical factors are discussed as well.

Acoustic Impedance Tests↗
PubMed1983

[Stapedius reflex. 2. Latency periods of the stapedial reflex].

The reflex thresholds and initial latency times of the stapedial reflex of 50 patients with normal hearing and cochlear hearing loss were examined using Madson ZO 73 equipment. The following results were obtained: 1. The initial latency times of the stapedius reflex diminish proportional to the supra-threshold loudness. 2. No significant difference of the latency times was found between 0.5, 1, 2 and 4 kHz. 3. The initial latency times of patients with positive recruitment (cochlear hearing loss) do not differ from those of patients with normal hearing.

Auditory Threshold↗
PubMed1980

[A contribution to the "acoustic-mechanical effect" of the ipsilateral registered stapedius-reflex (author's transl)].

The ipsilateral registered stapedius reflex is often reduced for intensity levels greater than 105 dB (SPL). Because of a reduced impedance, that is not influenced by the reflex arc, an "inverse" reflex curve can be registered. This phenomenon described by Lehnhardt et al. (1) as a "acoustic'mechanical effect" occurs without latency and interferes at levels higher than 105 dB (SPL) with the reflectory impedance change. This effect often dominates and causes a pronounced inverse ipsilateral reaction characterized by an impedance reduction. Frequently middle ears with a steep gradient of the tympanogram show an acoustic-mechanical effect. The missing reflectory component of the impedance change in deafness, in otosclerosis and in facial nerve disorders mostly causes an inverse impedance change. Investigations in temporal bone, in middle-ear models and from the middle ear of the guinea pig led to the assumption, that inverse impedance changes be related to coupling phenomenons of the tympanic-membrane and the ossicles. Excluding artifacts of the measuring device and investigating different states of the middle ear, it can be concluded, that these phenomenons are characteristic for intensity levels greater than 105 dB (SPL).

Acoustic Impedance Tests↗
PubMed1997

Evaluation of electrically elicited stapedius reflex threshold measured through three different cochlear implant systems.

OBJECTIVE: To evaluate intraoperative electrically elicited stapedius reflex thresholds (ESRTs) measured through three different cochlear implant systems: the Nucleus Mini 22, the Clarion Enhanced Bipolar, and the Med-El Combi-40. SUBJECTS AND METHODS: Relations between intraoperative ESRT and postoperative maximum comfort level (MCL) were examined in seven children (4 Nucleus, 2 Clarion, and 1 Med-El) and one adult (Clarion). RESULTS: Preliminary results indicated most ESRTs were either higher or both higher and lower (across the electrode array within a subject) than MCLs. All systems provided satisfactory means for measuring ERSTs. CONCLUSION: It is recommended that hand-held systems have a direct readout to the programming station and that audio and visual feedback be improved for all units.

Adolescent↗
PubMed1997

[The latency and time of the growing reflex in the stapedius muscle].

Latency time and rise time of the stapedius muscle reflex were examined in 32 healthy young people. No significant difference between woman and man were reflected. Obtained result were compared with the previous data of the various authors. Necessity of the own norm estimation of this parameters were emphasized.

Adult↗
PubMed1997

[A prognostic value of of stapedius reflex and accommodation coefficient in patients with Bell's palsy].

At 25 patients with Bell's palsy every 7 days stapedius reflex (SR), accommodation coefficient as well as improvement of mimical facial movements were examined. At 5 patients SR was noticed before treatment, at 13 after 14 days, at 4 after 21 and at 3 after 28 days since disease beginning. There was significant correlation between return SR and improvement of mimical facial movements, but there wasn't correlation between SR and accommodation coefficient.

Adolescent↗
PubMed1977

Stapedius reflex decay in myasthenia gravis.

Stapedius reflex decay, in response to a one-minute sound stimulus of 500 Hz occurred in six patients with myasthenia gravis. This decay is analagous to the decremental response of muscle action potentials to rapid nerve stimulation. Edrophonium chloride decreases the degree of decay. This represents a useful test in the diagnosis of myasthenia gravis.

Acoustic Stimulation↗
PubMed1976

Oscilloscopic analysis of the stapedius muscle reflex in brain stem lesions.

An oscilloscopic analysis of several features of the stapedius muscle reflex was carried out in a group of normal subjects and in patients affected by dysfunction at the brain stem level due to a pathologic lesion or temporary reduction by small doses of barbiturates. Under these conditions, the increased latency and reduced amplitude of the reflex, but particularly the reduced velocity and, not infrequently, the step-like pattern of the tracings, are considered to be data of considerable value in disorders of the brain stem structues.

Brain Diseases↗
PubMed1999

[The usefulness of intraoperatively registered, electrically evoked stapedius reflex for the programming of cochlear implants in children].

The programming of a cochlear implant speech processor used by young children is often difficult, especially when the stimulus level associated with maximum auditory loudness (MAL) needs to be determined. Excessively high stimulation should be avoided as this can have a traumatic effect. The aim of this study was to determine if a relationship exists between the intraoperatively determined electrical stapedius reflex threshold (ESRT) and the postoperatively determined MAL and hearing threshold for 27 patients, each having one of three implant types. The question of whether the ESRT provides a practical technique to simplify, improve and accelerate speech processor programming was investigated. For the monopolar stimulation mode used for the Med-El and Clarion implant systems, the average MAL and threshold was expressed as a percentage of the average ESRT across all electrodes. For the "common ground" stimulation mode used for the Nucleus implant system, a parabolic transformation was used to relate MAL and ESRT to one another. These transformations between MAL values calculated from the ESRT and the actual MAL values, determined psychoacoustically, diverged considerably from one another. Therefore, it was not possible to determine the MAL from the ESRT with certainty. The ESRT does, however, provide a means to estimate an approximate upper boundary for the MAL, apart from its use to control implant function. The determination of the exact MAL will still need to be determined using behavioural techniques.

Adolescent↗
PubMed1978

The central location of the motor neurons to the stapedius muscle in the cat.

In two cats and 10 newborn kittens, retrograde transport of horseradish peroxidase was used to locate the motor neurons of the stapedius muscle. Following injection of tracer into the muscle, labeled neurons were observed in the interface between the facial nerve nucleus and the caudal end of the lateral superior olivary nucleus. Some marked neurons were also located dorsal and ventral to the facial nucleus. The number of labelled cells varied from a low of 34 to a high of 199.

Acoustic Stimulation↗
PubMed1983

Histochemical characteristics of rabbit stapedius muscle.

A histochemical analysis of rabbit stapedius muscle fibers was conducted using the myofibrillar ATPase and NADH-tetrazolium reductase techniques. Two different fiber types, type 1 and type 2b, were identified. The functional significance of the results is discussed.

Adenosine Triphosphatases↗
PubMed1992

Middle ear development. I: Extra-stapedius response in the neonatal chick.

A laser interferometry system was used to study the ontogeny of tympanic membrane mechanical responses to sound as measured at the tip of the extra-stapedius (ES) in chicks. The ES velocity and phase responses in the frequency range between 0.2 and 10.0 kHz were measured in animals ranging from 3 days of age to adult. The slope of the low frequency response remained constant with age while the ES low frequency sensitivity increased by 11 dB. The sensitivity improvement indicated an increase in low frequency middle-ear admittance. However, there was no consistent developmental improvement in high frequency ES sensitivity. Comparisons between the growth of low frequency ES velocity, the development of admittance magnitude, and evoked potential threshold sensitivity developmental data indicated no clear relation between these measures.

Acoustic Stimulation↗
PubMed1987

Suprathreshold abnormalities of the stapedius reflex in acoustic tumor: a series of case reports.

Suprathreshold morphologic characteristics of the acoustic stapedius reflex are reported for five subjects with acoustic tumor. Results support the hypothesis that changes in suprathreshold morphology may be more sensitive to acoustic tumor than conventional reflex threshold and decay measures. Both the afferent relative amplitude index (AI) and measures of sequential variability of individual waveforms appear to be especially promising.

Adult↗
PubMed1987

Stapedius reflex and cerebellopontine angle tumours.

The stapedius reflex was investigated in 61 patients with cerebellopontine angle tumours, in order to evaluate the reliability of the reflex-decay test in VIIIth nerve disorders. The reflex was completely normal in 11% of the patients. The 2 most frequently observed abnormalities were (1) an absence of the reflex when stimulating the ear on the side of the tumour, and (2) the conjunction of pathological reflex-decay at 0.5 kHz with a unilateral threshold elevation and/or absence of the reflex at other frequencies. The decay test was normal in one-third of the patients with a preserved reflex.

Acoustic Impedance Tests↗
PubMed1992

Clinical observations on the on-off effect of the acoustic stapedius reflex.

The on-off effect of the acoustic stapedius reflex was found in association with several kinds of ear disease: otosclerotic stapes fixation, incudostapedial dislocation and sensorineural hearing loss. One fifth (8/40) of the patient group with an on-off effect and sensorineural hearing loss showed the typical symptoms of Ménière's syndrome.

Adult↗
PubMed1982

Stapedius reflex in curarized subjects: an index of neuromuscular weakness.

To examine the validity of the acoustical stapedial reflex (AR) as an index of neuromuscular weakness, the AR was measured along with other indices of muscle strength during administration of d-tubocurarine (dTc) to six healthy subjects. AR decreased immediately after each dTc dose and preceded changes in handgrip strength and respiratory muscle strength, but the peak effects of each dose similarly affected AR and other muscle strength. The findings with electrocutaneous stimulation and effects on growth function of the AR indicate that dTc affects primarily stapedius muscle contraction, the efferent portion of the reflex arc, and does not affect afferent or central portions of the reflex. We therefore conclude that the AR is a valid index of the integrity of neuromuscular transmission which promptly reflects early phase weakness. Unlike other measures of muscle strength, AR testing does not depend on subject cooperation, and involves no discomfort. The test therefore provides a useful means of assessing neuromuscular weakness.

Adult↗