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At least 73 records · Page 4Linked to original sources
PubMed1984

Extracochlear electrical stimulation.

Extracochlear electrical stimulation was carried out in 7 patients. We used square-wave signals. Electrode positions at the oval and round window showed the lowest current thresholds. The threshold of sound sensations elicited by electrical stimulation was higher in the high frequency than in the low frequency range. All 7 patients had hearing sensations for electrical stimulation with frequencies from 75 Hz to 1 000 Hz, 4 of them to 3 000 Hz. Varying the frequency of the electric signals gave variations of pitch sensation. A higher input amplitude gave variation in pitch sensation in some patients even if the electric frequency remained constant, at least for frequencies below 500 Hz. It seems possible to give prosodic information by transforming the speech from a microphone into electric pulses. This may be especially valuable information of the intelligibility of speech when combined with lip reading.

Auditory Threshold↗
PubMed1984

Perilymphatic fistula--a definitive and curable cause of vertigo following head trauma.

Vertigo or disequilibrium occurring in patients after concussive and nonconcussive head trauma may be due to a pathologic perilymphatic fistula from the inner ear through the oval and round window areas of the middle ear. Of 33 patients who had successful grafting of the fistulous area at middle ear exploration, 32 had resolution of vertigo, and 12 of 23 who had an associated hearing loss had improved hearing. Perilymphatic fistulas associated with vertigo and hearing loss after head trauma can be diagnosed with great certainty and are surgically curable in the great majority of cases. Patients with post-concussive syndrome, whose symptoms include vertigo or disequilibrium, should have a thorough otologic evaluation for the possibility of a perilymphatic fistula.

Craniocerebral Trauma↗
PubMedDate not supplied

Cochlear orientation and dimensions of the facial recess in cochlear implantation.

OBJECTIVE: To study the dimensions of the facial recess and the spatial relationship between the facial recess and the cochlea, using CT scanning in cochlear implantees. METHOD: In 29 cochlear implantees, preoperative CT scans of the temporal bone were compared with findings done at surgery. The dimensions of the facial recess and the relationship between the facial recess and the cochlea were both measured on a viewing station and classified on printed films by 3 blinded and independent reviewers. RESULTS: No significant relations could be found between either intuitive classification of facial recess width or electrode array insertion feasibility and the measurements with the viewing station. The 3 reviewers had large interobserver variability. In 5 cases, neither intuitive review of the CT scans nor viewing station measurements could predict any of the problems encountered during surgery. CONCLUSION: Our findings show that intuitive review was not reliable in classifying facial recess width. Viewing station measurements, in classifying the spatial relation between the facial recess and the cochlear basal turn, need a more detailed review in terms of the relationship with the operation direction and the orientation of the basal turn of the cochlea. Advanced imaging techniques, specifically multislice CT, might improve the diagnostic capabilities.

Chorda Tympani Nerve↗
PubMed1994

Perilymph pressure during hypobaric conditions--cochlear aqueduct obstructed.

Nine cats with the cochlear aqueduct surgically blocked were anaesthetised, put in a pressure chamber, and stepwise exposed to hypobaric pressure, each of the two steps lasting 5 min. The chamber pressure was reduced to -5 and -7 kPa. Concluding the experiment the cats were observed for 5 min after restoration of atmospheric pressure. The perilymph, tympanic cavity, cerebrospinal fluid, central venous, arterial and surrounding chamber pressures were continuously recorded. Reduced chamber pressure caused relative overpressure within the tympanic cavity, thereby inducing pressure gradients between the chamber, the tympanic cavity, the labyrinth and the cerebrospinal fluid and vascular pressures respectively. Our results demonstrate that hypobaric effects on the labyrinth are mediated via pressure changes in the tympanic cavity and not by systemic, vascular or cerebrospinal fluid influence. Substantial perilymph overpressure lasted throughout the hypobaric conditions. The magnitude and the duration of this overpressure were influenced by the patency of the Eustachian tube whereas the rate of the pressure change in the chamber was of little importance. As atmospheric pressure was restored in the chamber the overpressure in the labyrinth was reversed to underpressure--relative to pre-experimental conditions.

Animals↗
PubMed1989

Spontaneous perilymphatic fistula in children.

Treatment of fistulae in children should be targeted at four different problem areas. The surgical intervention of these fistulae is most efficacious in controlling recurrent meningitis, which has not been discussed in this paper, and in the controlling of vestibular symptoms. Whether or not it will stop the progression of hearing loss or restore hearing is not known in a group of patients. It has been documented in this and other reports that the closure of the fistula will in specific cases appear to be associated in time with a stopping of the progression of the hearing loss and is associated also in time with the restoration of hearing function. Various factors must be considered in developing criteria for intervention. A decision to explore the ear should be based on history, audiometric change, vestibular testing including a fistula test, and malformation of bony labyrinth.

Adolescent↗
PubMed1989

Effects of round window membrane rupture on cochlear blood flow and inner ear pressures.

Effects of round window membrane rupture on cochlear blood flow and inner ear pressures were investigated using non-radioactive microspheres and a servo-micropipet system in guinea pigs. When perilymphatic pressure was raised through a glass capillary tube inserted into the perilymphatic space, both endolymph pressure and perilymph pressure rose. When these inner ear pressures were raised to relatively high levels, cochlear blood vessels could be compressed and endocochlear potential decreased to a negative value due to the interruption of cochlear blood flow. However, in the case when the round window membrane was ruptured by further increase in perilymph pressure, the inner ear pressures decreased and restoration of cochlear blood flow and endocochlear potential was observed. When the round window membrane was ruptured with a fine needle under ordinary inner ear pressures, cochlear blood flow did not change significantly.

Animals↗
PubMed1995

The equality of volume displacements in the inner ear windows.

The equality of volume displacements in the inner ear windows is commonly assumed. In the present work this assumption is experimentally verified. The stapes is given a known displacement. The volume displacement of the round window is determined by measuring the sound pressure set up in a tube cemented to the round window. Inner ears of pigs have been used in the investigation. Supplementary measurements on one human temporal bone have been performed. The equality of the volume flows in the inner ear windows is also supported through an analysis of earlier measurements of the round window displacement for a given sound-pressure level at the eardrum.

Acoustics↗
PubMed1983

Perilymph fistulas in infants and children.

During the years 1975 through 1981 we performed exploratory tympanotomies on 33 infants and children (44 ears) to verify the presumptive diagnosis of perilymph fistula (PLF). A PLF was identified at the round window, oval window, or both in 29 (66%) of the 44 ears explored. After surgery hearing was unchanged in 86%, improved in 5%, and worsened in 9% of the ears in which PLFs had been observed. Complaints of vertigo subsided in all children in whom a PLF was repaired. Preoperative factors determined to be highly suggestive of the presence of a PLF included the following: sudden onset of sensorineural hearing loss (SNHL), congenital deformities of the head, and abnormal findings on tomograms of the temporal bones, especially Mondini-like inner ear dysplasias. Middle ear abnormalities (primarily congenital) were observed in 20 of the 44 ears. Abnormal results of preoperative vestibular function studies, which included a fistula test, and sex were not consistently found to be associated with an observed PLF at tympanotomy.

Adolescent↗
PubMed2005

[Pharmacokinetics of the methylprednisolone, dexamethasone and hydrocortisone in the inner ear after administered via round window].

OBJECTIVE: To compare the pharmacokinetics of Methylprednisolone, Dexamethasone and Hydrocortisone in the inner era of guinea pig after administered via round window. METHOD: Guinea pig was divided into groups chronologically. After a drop of 100 g/L corticosteroid applied into the round window niche, the tympanic perilymph was sampled chronologically. Concentration of the three corticosteroid in perilymph were measured via HPLC and analyzed by 3P97 software. RESULT: The highest concentration of the three drug appeared at 30 min, 60 min and 30 min. Then the concentration declined rapidly. CONCLUSION: All three corticosteroid permeate the round window membrane easily, but the concentration declined rapidly after the peak appearing.

Administration, Topical↗
PubMed1996

[High resolution computerized tomography of middle ear abnormalities].

BACKGROUND: The aim of this study was to analyze malformed petrous bones with computed tomography and to develop a radiologic score which can help to judge the indication for operative reconstructions. METHODS: One hundred forty-two petrous bones in 71 patients with unilateral or bilateral microtia, atresia of the external auditory canal, and malformations of the middle ear were evaluated with high-resolution CT. RESULTS: In 97% of patients with severe auricular dysplasia, there was dysplasia of the middle ear ossicles; in 70% the stapes was malformed. In 32% the oval window was occluded, and in 7% the round window. In 75%, the canal of the facial nerve was displaced, and 16% also showed abnormalities of the labyrinth. A close correlation between the malformation of the auricle and of the middle ear was not found. CONCLUSIONS: High-resolution CT is necessary for the evaluation of malformed middle ears. Based on the abnormalities described, we propose a radiologic score for the assessment of malformed petrous bones. This consists of the following criteria: external auditory meatus, pneumatization of the mastoid and of the tympanic space, size of the tympanic space, facial nerve, vessels, malleus and incus, stapes, oval and round window. The graded points of each structure are added up to the score, which might range between 0 and 28. This score can help to judge the indication for reconstruction of the middle ear. In bilateral malformation we suggest a middle ear reconstruction of the better hearing ear if the score is greater than or equal to 15, and in unilateral malformation if it is at least 20. In patients with lower scores, we only suggest hearing aids.

Adolescent↗
PubMedDate not supplied

Simultaneous round and oval window fistulae in a child.

Sudden hearing loss from simultaneous rupture of both oval and round windows, occurring in the only hearing ear of a child, is described. The condition was surgically managed with recovery of hearing. Of particular note was the presence of air aspirated into the labyrinth at the time of membrane rupture, which has not previously been described. The possible mechanisms and some clinical correlates associated with anatomic predisposition to such rupture are discussed.

Child, Preschool↗
PubMed1984

Ear canal acoustic and round window electrical correlates of 2f1-f2 distortion generated in the cochlea.

Close parallels have been found between the behaviour of the distortion product 2f1-f2 measured acoustically in the meatus (ACDP) and the 2f1-f2 component (CMDP) measured in the gross cochlear electrical response from the round window during two-tone stimulation. The two response modes show comparable growth with increasing stimulus intensity. Their group latencies and their frequency-selective susceptibility to suppression by a third tone are very similar. The common origin of these two responses is discussed.

Acoustic Stimulation↗
PubMed1980

Oval and round window changes in otitis media. Potential pathways between middle and inner ear.

A longitudinal sequential study of oval and round window changes in otitis media in an experimental animal (cat) using Eustachian tube obstruction was done. Thirty-two animals were used. In this first sequential study of the oval and round windows in otitis media, the continuum of round window membrane changes from 1 day to 6 months after obstruction revealed changes to be gradual and similar to those of the mucoperiostium. These changes are suitable for changes in permeability and suggest that this membrane is a very likely pathway from the middle to the inner ear. Bony fistulas were not observed and the oval window remained essentially unchanged in time, thus they were not considered routes into the inner ear. Other possible routes are discussed.

Animals↗