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At least 19 recordsLinked to original sources
PubMed1979

Factors influencing the acoustic-immittance characteristics of the acoustic reflex.

Measurements of the aural acoustic-immittance (admittance and impedance) characteristics of the middle-ear transmission system in humans during the quiescent (static) and reflexive states were made (N = 36) utilizing a signal-averaging technique. Three pure tones (750, 1000, and 2000 Hz) and broadband noise stimuli elicited the acoustic reflex in 2-dB steps at sound-pressure levels from 84-116 dB (tones) and 66-116 dB (noise) during ascending- and descending-intensity level runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an admittance meter. A computer corrected for the ear-canal volume utilizing measurements made at ear-canal pressures of 0 and --350 daPa and then converted the conductance and susceptance values into admittance and impedance units. The results were reported in absolute and relative immittance units, including components, as a function of both stimulus sound-pressure level and intensity level above the acoustic-reflex threshold. The static immittance of the middle ear changed nonlinearly over time to lower admittance or higher impedance values. The influence of this static-immittance shift on the reflex magnitude was discussed. The largest mean reflex magnitude and the slowest rate of growth were observed with broadband noise, although eight of the 36 subjects demonstrated the largest reflex magnitude in response to one or more of the tonal stimuli. Although static-immittance values and acoustic-reflex thresholds were poorly correlated, the reflex magnitudes were proportional to static immittance. The variability of the reflex measures was similar to the variability of the static-immittance values. Finally, bi-directional changes in resistance during the reflexive state were observed and discussed.

Acoustic Impedance Tests↗
PubMedDate not supplied

Cerebellopontine angle tumours, other than acoustic neuromas. A report on 34 cases. A presentation of 7 bilateral acoustic neuromas.

The symptoms, preoperative diagnostic results and histological findings in 34 cerebellopontine angle tumour cases, other than acoustic neuromas, are presented. The meningeomas dominate by far this group of tumours. The symptomatology is much less uniform than that of the acoustic neuromas, where the VIII nerve is dominant. The facial nerve is less involved, whereas the other cranial nerves give symptoms more frequently. One remarkable sign is the presence of severe trigeminal neuralgia, which we have not encountered in acoustic neuromas. Only 35% of the 'non-neuroma' patients had elevated spinal fluid protein, compared with 100% in our acoustic neuroma cases. Furthermore, 7 patients with bilateral acoustic neuromas are presented. The connection with von Recklinghausens disease and multiple meningeomas is discussed.

Adult↗
PubMed1992

The feasibility of using oto-acoustic emissions to monitor cochlear function during acoustic neuroma surgery.

The feasibility of using evoked oto-acoustic emission (EOAE) measurement for intra-operative monitoring of cochlear function was assessed during removal of an acoustic neuroma in a 53-year-old woman with normal hearing on the operated side prior to surgery. The high level of noise in the operating theatre was the only material problem encountered and this was not sufficient to prevent recording of identifiable waveforms. During manipulation of the brainstem, damage to the cochlea was indicated by an increase in EOAE latency and its eventual disappearance. A total hearing loss in the operated ear was revealed after surgery. Monitoring cochlear function with EOAEs is probably best considered at present as an adjunct to auditory brainstem response monitoring of the composite cochlea and eighth nerve, thus providing differential information.

Cochlea↗
PubMed1976

Acoustic reflex test in neuro-otologic diagnosis. A review of 24 cases of acoustic tumors.

Acoustic and other tumors of the cerebellopontine angle are not uncommon, and they usually have otologic symptoms or findings. Early diagnosis depends on a high index of suspicion and a thorough evaluation of patients with suspected tumors. This is a report of 24 cases selected from a group of 184 surgically confirmed tumors. Had the cases been evaluated only on the basis of pure tone or speech audiometry or on the basis of plain roentgenograms, the diagnosis might not have been made. Audiological examination should include the acoustic reflex test. The results of this test indicated a retrocochlear problem (absence or decay of the reflex) in 19 of 24 cases (80%). The test was positive in 11 of 12 patients with normal or near normal hearing and in seven of eight patients with normal x-ray films.

Adolescent↗
PubMed1975

[Bilateral tumors of the acoustic nerve and Recklinghausen's disease observed in several generations. Considerations on heriditary acoustic nerve tumors].

Since 1933, four families have been found in Marseilles with bilateral tumours of the acoustic nerve spread over three generations in three families. The fourth only showing a cutaneous neuro-fibromatosis in the second generation. The authors recall briefly the clinical characteristics and compare their cases with similar ones found in the literature. Bilateral and familial neurinomas of the VIIIth cranial verbes were found in 21 families, making a total of 111 cases, unilateral neurinoma being used as a term of comparison. Among the groups of cases published, the family observed by Gardner and Frazier is the most remarkable (43 cases over 6 generations). From the hereditary point of view, the phenomenon of antiposition is not always constant. From the evolutionary point of view, bilateral neurinomas manifest themselves earlier clinically than unilateral ones. As far as associations are concerned, cutaneous manifestations of neuro-fibromatosis are the most frequent if the neurinomas are bilateral and non familia. Among tumors of the nervous system, meningiomas and gliomas have been found, other dysembryoplastic or degenerative tumoral associations being rare. The incidence of cutaneous symptoms is very low when the neurioma is unilateral. The association of cutaneous symptoms with bilateral and familial neurinomas does not worsen the prognosis, but the presence of such cutaneous signs is significantly more serious if the neurinoma is isolated. These considerations do no more than touch the fringes of the problems raised by these sporadic or hereditary tumours of the VIII the cranial nerves, developing within the framework of phacomatosis. Great caution is necessary in assessing the correlations observed in view of the narrow range of statistics available.

Deafness↗
PubMedDate not supplied

[Influence of the contralateral acoustic stimulation on the acoustic otoemissions: response modulation by the efferent olivocochlear system].

We have correlated in 16 patients (32 ears), the modifications de EOEs before and after sound stimulation of the contralateral ear. The recording of the EOEs has been performed in a sound proof room with ILO 88 from Otodynamics Ltd., the analysis has been made with the ILO 88 V.3.5 software. We have tried to study the modulator rol of the medial efferent coclear system on the external ciliated cells. In the results we observe a decrease of the amplitude in the EOEs when the contralateralmears is stimulated a white noise, in relation with the nonstimulation situation. When pures tones are used contralateral stimulation the decrease in the EOEs amplitude takes place in the same frequency spectrum as the pure tone used.

Acoustic Stimulation↗