Contralateral Stapedius Reflex Research Articles

A clinical analysis for sudden sensorineural hearing loss with acoustic neurinoma

Retrospectively analyzed the clinical data of sudden sensorineural hearing loss with acoustic neuroma. The clinical data of 467 cases with sudden sensorineural hearing loss were collected between Jan, 2008 and Aug, 2012. Discussed the clinical data which were diagnosed as acoustic neuroma. In 467 cases of sudden sensorineural hearing loss, nine cases were diagnosed as acoustic neuromas (9 ears, 1.93%), two males and seven females, with a age range of 28 to 57 years. Among them, seven cases accompanied with tinnitus, seven cases with vertigo. The hearing results in nine cases, two cases were found to be mild, two were moderate, four were severe, and one was profound hearling loss respectively. Hearing was classified into five types according to audiogram shape (1 of up-sloping, 1 of down-sloping, 2 of mid-frequency, 1 of profound loss, 4 of flat audiogram). Eight cases had abnormal ABR, nine cases with ear ipsilateral stapedius reflex were completely not elicited, seven cases with health ear contralateral stapedius reflex were completely not elicited. Tumors were graded by Koos Grades according to size (7 of grade I, 1 of grade II, 1 of grade IV). Seven small acoustic neuroma was taken waiting strategies. Meanwhile, we use glucocorticoid and improve the microcirculation of the inner ear medication short-termly for these patients. Four patients' hearing were improved. The initial symptoms of some acoustic neuroma are sudden hearing loss, especially the small tumors in internal auditory canal. In order to prevent misdiagnosis, MRI and ABR should be performed as a routine test for sudden sensorineural hearing loss. It is necessary to give appropriate treatment to protecting hearing for the small acoustic neuroma patients whose first symptoms are diagnosed as sudden sensorineural hearing loss.

Influence of anaesthetic agents on transient evoked otoacoustic emissions and stapedius reflex thresholds

This aim of this study was to determine the effect of anaesthetic agents on stapedius reflex (SR) thresholds and transient evoked otoacoustic emissions (TEOAE). Fifty patients who were scheduled for operation and who had normal hearing were included in the study. All were given midazolam for premedication and propofol for induction. Anaesthesia was maintained in five different ways in each group of 10 patients. Groups I-IV received inhalational anaesthesia: group I received 70 per cent N2O plus 30 per cent O2, group II sevoflurane, group III desflurane and group IV halothane. Group V received total intravenous anaesthesia with propofol plus sufentanil. The SR and TEOAE of the patients were measured four times: on the day before surgery (first measurement), after premedication (second measurement), after induction of anaesthesia (third measurement) and during maintenance of anaesthesia (fourth measurement). Midazolam significantly increased ipsilateral and contralateral SR thresholds and decreased TEOAE wave reproducibility. Propofol significantly increased only the SR thresholds. The other anaesthetic agents significantly increased only the contralateral reflex thresholds. Of these, the highest increase was seen after sevoflurane and the lowest after halothane. The changes in TEOAE wave reproducibility due to anaesthetic agents used for maintenance were not significant. We concluded that midazolam premedication may affect audiological evaluation with SR and TEOAE tests, and sevoflurane should not be used when it is necessary to measure SR under general anaesthesia.

Childhood otitis media and electrically elicited stapedius reflexes in adult cochlear implantees.

Electric stapedius reflex thresholds are helpful in programming cochlear implants, but only approximately two-thirds of patients have identifiable reflexes. Childhood otitis media correlates with absent stapedius reflexes or with high electric stimulation needed to elicit a reflex in cochlear implantees. Twenty-five adults with acquired hearing loss who underwent implantation with the MED-EL COMBI 40+ standard electrode array. STUDY PARAMETERS: The extent of temporal bone pneumatization, an indicator of childhood otitis media, was measured from preoperative computed tomographic images. Clinical units (in microamperes) needed to elicit a contralateral stapedius reflex, or maximum stimulation tried, were recorded. No definite association of pneumatization volume with intensity of stimulation was observed. The null hypothesis of no association cannot be rejected. Childhood otitis media does not seem to explain absent electric stapedius reflexes and the wide range of clinical units needed for maximum comfortable loudness level. Remaining potential explanations probably include the wide range of cochlear neurons that can be electrically stimulated, and that the maximum tolerable stimulation is too low to elicit a stapedius reflex.

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.

Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant.

The effect of stimulus duration on the threshold of the contralateral stapedius reflex was investigated in patients supplied with a Vienna cochlear implant (analog stimulation via CI) and compared to results of a normal-hearing reference group in case of acoustic stimulation. Changes in reflex threshold were determined at four frequencies (125, 500, 1,000 and 2,000 Hz in case of electrostimulation and at 500, 1,000, 2,000 and 4,000 Hz for acoustic stimulation) and for five durations (30, 50, 100, 300 and 500 ms). The comparison of the two stimulation modes was accomplished by using the same instrumentation and procedure. Reflex threshold was evaluated according to an objective criterion based on the individual noise distribution of recordings without reflex and by subjective judgement. For both stimulation modes a strong effect of stimulus duration on reflex threshold was observed (p < 0.001). The amount of temporal integration reflected by the threshold difference between 500 and 50 ms was approximately 2-4 dB for electrical stimulation via CI and 6 dB for acoustic stimulation in normal-hearing individuals. In case of electrostimulation, the reflex threshold for stimuli of 30 ms was most often above the limit of uncomfortable loudness sensation; the increase in reflex threshold for acoustic stimulation between 500 and 30 ms was approximately 14 dB. There was no evidence of frequency effect on reflex threshold nor an interaction between frequency and stimulus duration for either stimulation mode.

Stapedius reflexes to electrical stimulation in the rabbit for the assessment of hearing

The possibility of using electrically induced stapedius reflexes as a means of objective hearing evaluation was investigated in the rabbit as an animal model. The contralateral stapedius reflex to acoustic and electrical stimulation was measured in anesthetized rabbits. For electrical stimulation, the middle ear was opened surgically and stimulation was applied by a monopolar electrode placed at or into the round window. Contraction of the middle ear muscle was monitored by digital sampling and averaging of the impedance changes in the contralateral ear. Acoustically evoked reflexes were recorded within expected limits despite anesthesia. The level of the electrical stimulus was raised until mass reflexes of the neck muscles were observed. A contralateral stapedius reflex to electrical stimulation could not be demonstrated. In our experiment, monopolar electrical stimulation at the round window could not elicit contralateral stapedius reflexes.

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.

Stapedius Reflex Growth Function in Cochlear Implant Patients

The growth function of the contralateral stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 9 patients and compared to reflex functions obtained for acoustic stimulation in 3 normal-hearing subjects. Sinusoidal signal bursts with the same time pattern were used for the two stimulation modes, the contraction of the middle ear muscle was monitored by sampling the compliance change in the contralateral ear. The reflex amplitudes were found to increase with increasing stimulus intensity in all individuals except in 1 with electrical stimulation. The slope of the intensity function for electrostimulation ranged between 5 and 85%/dB and in the acoustical mode between 2 and 4%/dB. In case of electrostimulation a frequency effect was observed.

Extramedullary leukemia with central facial palsy originated from poorly differentiated abdominal lymphoma

An 8-year-old boy was presented with central facial palsy caused by extramedullary leukemia which had originated from poorly differentiated abdominal lymphoma. On cerebral tomographic scanning, there were adherences in the basal area of the brain. The occurrence of central facial palsy is very rare in childhood leukemia. However, in this case facial palsy was central in type and appeared as the presenting sign. The occurrence of central facial palsy was confirmed by the absence of clinical, radiological and audiological signs of peripheral involvement. The contralateral stapedius reflex test (500, 1000, and 2000 Hz) was present in this case.

Stapedius reflex threshold in cochlear implant patients.

The contralateral stapedius reflex elicited by sinusoidal electrostimulation via cochlear implant was investigated in 12 patients. Contraction of the middle ear muscle was monitored by time-resolved synchronized digital sampling of the impedance change in the contralateral ear. The reflex was detected in all patients in whom the uncomfortable loudness level (UCLL) could be reached and who had intact middle ear function. Generally, the reflex threshold is located in the upper part of the dynamic range between the most comfortable loudness (MCL) and the UCLL. The demonstrated method may provide suitable assistance in speech processor adjustment in difficult-to-test patients.

Effect of ketamine on the stapedius reflex in the squirrel monkey.

We evaluated the effect of ketamine hydrochloride on the acoustically elicited stapedius reflex of squirrel monkeys. After intramuscular injection, in the presence of normal tympanometry, the amplitude of the contralateral stapedius reflex was severely depressed, even at low, preanesthetic dose levels. Possible mechanisms for the mediation of this unexpected effect are discussed.

Stapedius reflex quantification in acoustic tumor patients.

This investigation is a human application of previously reported work from our laboratories on experimental acoustic tumor effects on the stapedius reflex in monkeys. In this study, the contralateral stapedius reflex was elicited in human controls and in subjects with an acoustic tumor. Acoustic impedance was recorded on magnetic tape for offline analysis of reflex threshold, latency, rise, amplitude, decay, and relaxation. Typical tumor effects on threshold and decay were observed. Most important was the demonstration that decay measured at 20 db SL was more sensitive and more specific for tumor than decay measured at the conventional 10 db SL. Stapedius reflex latency, rise, and amplitude were more sensitive to the presence of a tumor than were measures of threshold and decay. These data indicate that qualification of the reflex will increase the utility of the test.

Recovery of the Human Intra-Aural Muscle Reflex After “Pauses” of Various Depth

Decay and recovery of the ipsilateral and contralateral stapedius reflex were studied in eight normal hearing subjects. The activity of the intra-aural muscle was recorded as a change of the ear's acoustic impedance in response to prolonged stimulation at 2 000 Hz. A one-second long attenuation of the stimulus tone by 2 to 40 dB was introduced when the response had decayed to a certain level. The recovery following the "pause" was observed. The results show that a "pause" with a depth as small as 2 dB produced approximately 40% of total recovery. A 20 dB attenuation resulted in a recovery equal to that seen after an interruption of the tone. No difference was seen between the ipsilateral and the contralateral reflex. The possibility of using stapedius reflex recovery for diagnosis of otoneurological disorders was discussed.

Planimetrische Untersuchungen des kontralateralen Stapediusreflexes

In 327 normal-hearing and hearing impaired patients contralateral stapedius reflexes were measured by planimetrical methods. Measurements were taken of the recovery phase (slope), of the reflex, of the partial and the complete reflex-area and the amplitude. A total number of over 3000 contralateral stapedius reflex curves in children, adults as well as hearing impaired patients (noise exposed) were statistically analysed. Distinct differences appeared by correlating intensity to amplitude, recovery phase (slope) and area. Results of i.e. recovery phase were highly significant comparing normal-hearing and hearing impaired patients.

Decay and recovery of the acoustic stapedius reflex in humans.

The time course of decay and recovery of ipsilateral and contralateral stapedius reflex responses to 2 000 Hz pure tone stimulation was studied in 10 normal-hearing subjects. Reflex responses were found to follow a closely similar time course with respect to both decay and recovery in simultaneous bilateral recordings. The similarity is compatible with the assumption that decay and recovery originate in the afferent auditory system, and not in the muscles. Recovery was 50% complete 250 ms after the end of the stimulus and most subjects had reached their initial amplitude after 1-3 s. The individual correlation between decay and recovery was negative but weak, which is interpreted as showing that these processes have a tendency to balance each other, but are based partly on different mechanisms. The implications of the present results for diagnosis of disorders of the lower auditory system as well as for the evaluation of the protective role of the stapedius reflex against noise damage are pointed out.

Normal values of the ipsilateral acoustic stapedius reflex threshold.

It is frequently taken for granted that the acoustically evoked stapedius reflex is bilaterally symmetrical. Contrary to this, Møller described an asymmetry of the acoustic stapedius reflex with an ipsilaterally 2--14 dB lower threshold. The determination of normal values of the ipsilateral acoustic stapedius reflex threshold with a large number of patients is difficult as the intensity of the stimulus depends considerably on the position of the probe in the acoustic meatus and is therefore not defined with sufficient accuracy. For this reason we determined the values of the ipsilateral threshold by applying a stimulus sound of high intensity to the deaf ear of unilaterally completely deaf patients with a normal headphone, which can be calibrated much more accurately. After subtraction of the individual cross hearing loss, the exact ipsilateral intensity was obtained. By this method a stapedius reflex could be evoked with 49 of the 62 patients. By mathematical consideration of the data of the positive cases, as well as the maximum available intensities with the negative cases, determination of the median value of the ipsilateral threshold was possible: at 0.5 kHz 59 dB; at 1kHz 62.5 dB; at 2 kHz 67 dB; at 4 kHz approx. 67 dB. The difference between ipsilateral and contralateral stapedius reflex threshold was in the range of 15 dB. A new definition of the normal value for the ipsilateral measured Metz recruitment appears necessary.

The stapedius reflex in the diagnosis of myasthenia gravis

The contralateral stapedius reflex, elicited by a clearly-defined auditory stimulus, was studied in 3 patients with myasthenia gravis. The reflex was assessed by recording the change which occurred in the acoustic impedance of the middle ear. In all patients a decay (decrement) of the reflex was found, interpreted as a sign of increased fatiguability at the neuromuscular junction of the stapedius muscle. The reflex recovered rapidly after the intravenous injection of a cholinesterase inhibitor (Tensilone̊g;). It is concluded that the stapedius reflex test can be of value in the diagnosis of myasthenia gravis, since it can be well-standardized, involves a muscle innervated by the facial nerve and is not disturbing to the patient, whose active cooperation is not necessary.