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At least 109 records · Page 6Linked to original sources
PubMed1990

[Recurrence of perilymphatic fistula].

Recurrence of the perilymphatic fistula is not rare and may be a tough problem for surgical treatment. This is because a graft is usually applied on the ruptured window(s) from the middle ear and therefore the perilymphatic pressure directly acts on the graft. The recurrence may be caused by a technical failure, use of an unsuitable graft material, poor postoperative bedrest, trauma, increased inner ear pressure, etc. In our clinic, the recurrence occurred in 7 of 48 cases surgically treated. Vertigo accompanied with spontaneous or positional nystagmus was seen in all 7 recurrent cases, while only 2 of them complained of worsening of the existing hearing loss. Re-operation was carried out in two patients. In the first case, closure of the round window by the previous operation was found incomplete, and the perilymph leaked through the gap around the graft. In the second case, closure of the round window was complete, but perilymph leaked from the oval window. In order to prevent the recurrence, the operation should be carefully performed by using strong and adhesive tissue as a graft material, applying a glue between the graft and the inner ear window(s), and keeping strict postoperative bedrest.

Adolescent↗
PubMed1984

High-frequency rolloff in a cochlear model without critical-layer resonance.

Zwislocki's original cochlear model, incorporating axial fluid inertia and shunt basilar-membrane stiffness and viscous resistance, possesses an operating regime not previously emphasized in the literature. Even in the absence of basilar-membrane mass and the consequent critical-layer resonance, this regime provides extraordinarily steep high-frequency rolloff. That rolloff is not associated with a critical frequency at which energy flow velocity goes to zero, but is attributable instead to a combination of two effects; (1) frequency-dependent energy coupling to the basilar-membrane viscous resistance, leading to local attenuation of the traveling wave at a rate (Np/cycle) that is directly proportional to frequency, and (2) wavelength that decreases with increasing frequency, thus increasing the number of cycles per unit length of basilar membrane. This combination leads to local attenuation of the traveling-wave amplitude (hence energy absorption from the traveling wave) that is strongly dependent on frequency, the rate (Np/cm) being proportional to the square of frequency in the long-wave mode. In Ranke's (two-dimensional, short-wave mode) version of the model, the same operating regime leads to attenuation that is even more intensely dependent on frequency, the rate being proportional to the cube of frequency.

Basilar Membrane↗
PubMed1984

Permeability of the round window membrane.

Cefmetazole sodium, a cephamycin antibiotic, was shown to pass through the round window membrane into the inner ear of the guinea pig. The concentration of the drug in the inner ear fluid indicated that a larger amount of the drug reached the inner ear through the round window membrane than when administered intraperitoneally.

Animals↗
PubMed2001

Quantification of solute entry into cochlear perilymph through the round window membrane.

The administration of drugs to the inner ear via the round window membrane is becoming more widely used for both clinical and experimental purposes. The actual drug levels achieved in different regions of the inner ear by this method have not been established. The present study has made use of simulations of solute movements in the cochlear fluids to describe the distribution of a marker solute in the guinea pig cochlear fluid spaces. Simulation parameters were derived from experimental measurements using a marker ion, trimethylphenylammonium (TMPA). The distribution of this ion in the cochlea was monitored without volume disturbance using TMPA-selective microelectrodes sealed into the first and second turns of scala tympani (ST). TMPA was applied to perilymph by irrigation of the intact round window membrane with 2 mM solution. At the end of a 90 min application period, TMPA in the first turn, 1.4 mm from the base of ST, reached an average concentration of 330 microM (standard deviation (S.D.) 147 microM, n = 8). TMPA in the second turn, 7.5 mm from the base of ST reached a concentration of 15 microM (S.D. 33 microM, n = 5). The measured time courses of TMPA concentration change were interpreted using the Washington University Cochlear Fluids Simulator (V 1.4), a public-domain program available on the internet at http ://oto.wustl.edu/cochlea/. Simulations with parameters producing concentration time courses comparable to those measured were: (1) round window permeability: 1.9 x 10(-80 cm/s; (2) ST clearance half-time: 60 min; (3) longitudinal perilymph flow rate: 4.4 nl/min, directed from base to apex. Solute concentrations in apical regions of the cochlea were found to be determined primarily by the rate at which the solute diffuses, balanced by the rate of clearance of the solute from perilymph. Longitudinal perilymph flow was not an important factor in solute distribution unless the bony otic capsule was perforated, which rapidly caused substantial changes to solute distribution. This study demonstrates the basic processes by which substances are distributed in the cochlea and provides a foundation to understand how other applied substances will be distributed in the ear.

Animals↗
PubMed1993

[Acute sensory deafness originating from experimental double-membrane rupture].

Combined rupture of Reissner's membrane and the round window membrane (double-membrane rupture) as a cause of acute profound sensorineural hearing loss was investigated in guinea pigs. Action potentials (APs) of the cochlear nerve in response to tone pip stimuli (1, 2, 4, 8kHz) were recorded before and after rupture of Reissner's membrane at each turn of the cochlea. Then the round window was perforated to create leakage of the perilymph. Ninety minutes later, AP was again recorded. After these procedures, the animal was sacrificed for histological study to confirm the rupture of Reissner's membrane. The ears with double-membrane rupture showed a larger decrease in AP amplitude at all test frequencies than did control ears with round window rupture alone. The ears in which Reissner's membrane was ruptured at the second turn showed more a pronounced decrease in AP amplitude than those ruptured at the third and apical turns. It was concluded that double-membrane rupture could be a cause of sudden deafness, but that the disturbance of cochlear function depends on where Reissner's membrane ruptures.

Action Potentials↗
PubMedDate not supplied

Distribution of HRP in the inner ear after injection into the middle ear cavity.

The distribution patterns of horseradish peroxidase (HRP) reaction products in the inner ears of guinea pigs were studied after injections into the middle ear cavities and perilymphatic and subarachnoid spaces. The normal round window membrane resisted HRP penetration from the middle ear side, but when it became pathological after repeated applications, its permeability increased. HRP deposits were found in the cochlear and vestibular sensory cells and in the lumen of the endolymphatic sac. HRP reaction products were minimal at the cochlear apex even after long survival times, suggesting that perilymph flow, if it exists, is rather weak toward this direction. Whereas the stria vascularis is impermeable to HRP, the vestibular dark cells were accessible; thus, the metabolic activity of the dark cells can be more readily controlled by drug applications through the middle ear cavity. The finding of HRP deposits on the scala vestibuli surface of Reissner's membrane and the absence of HRP in the upper portion of the spiral ligament at the basal turn suggests that the oval window is a secondary route of passage for these particles from the middle ear cavity to the inner ear. In order to determine the route of HRP into the endolymphatic sac from the middle ear cavity or scala tympani, the cochlear and/or vestibular aqueducts were obliterated singly or together. The route of HRP was determined to be the vestibular aqueduct. HRP is believed to enter the sac lumen through Reissner's and saccular membranes and the sac epithelium. Drugs and other large molecular substances instilled in or gaining access to the middle ear cavity may reach the endolymphatic sac causing its functional alteration.

Animals↗
PubMed1990

Comparison of immune-mediated models of acute and chronic otitis media.

The distribution of immunoglobulin-bearing cells and the pattern of histopathological changes in the middle ear (ME) mucosa, round window membrane (RWM), and inner ear were compared during acute and chronic immune-mediated otitis media with effusion (OME) in the guinea pig as an animal model. In both acute and chronic immune responses (IRs), mucosal hyperplasia, edema, neovascularization, and cellular infiltration were observed. IgG+ cells were predominant in both the acute and chronic IRs. The number of IgA+ cells, however, increased in the mucosa and RWM during chronic IRs. Only the chronic IR resulted in gland formation within the ME and inflammation within the cochlea. These results indicate that the chronic IR was more similar to reports of clinical OME than the acute IR. The cochlear inflammation associated with chronic OME can lead to sensorineural hearing loss, as reported in clinical studies.

Acute Disease↗
PubMed1987

Labyrinthine window rupture with round window predominance: a long-term review of 32 cases.

A retrospective series is presented of 32 cases of spontaneous labyrinthine window rupture proven at tympanotomy. There was no prior history of stapedectomy or other middle ear surgery. Seventy-eight per cent of cases involved the round window, in contrast to previous series on the subject. The pattern of hearing loss and vestibular symptoms varied widely and followed different antecedent factors, the commonest of which was head injury (46.9%). Including cases misdiagnosed initially, 92.9% of patients with vestibular symptoms experienced improvement following surgery, but only 20.7% of patients had improved hearing; these figures changed with long-term follow-up, which has been rarely reported previously. Seven patients, the majority oval window ruptures, required re-exploration, mainly for vertigo, and prolonged follow-up is required.

Adolescent↗
PubMed1993

Congenital perilymphatic fistula and associated middle ear abnormalities.

To specifically determine the frequency and type of middle ear abnormalities associated with perilymphatic fistula (PLF), a retrospective chart review was performed of 94 patients (117 ears) who underwent exploratory tympanotomy for PLF from 1980 to 1989. Of the 117 ears explored, 80 (68.4%) had a PLF, and in 65 (81.3%) of these ears, a middle ear malformation was associated with the PLF. Of these 65 ears in which a congenital middle ear abnormality was observed, a malformed stapes was the most common abnormality seen (39 ears, 60%), followed by a deformed round window (20 ears, 30.8%), a deformed incus (11 ears, 16.9%), and a deformed promontory (2 ears, 3%). Often these malformations coexisted amongst themselves or with inner ear abnormalities. Sixteen children (25 ears) had an inner ear malformation identified on computed tomography (CT); all of these children had a PLF found at the time of surgery. This study demonstrated that 86.3% of the ears found to have a PLF had a deformity of the middle ear, inner ear, or both. A malformation of the stapes, most frequently identified as a deformity of its superstructure (and presumably also the anterior footplate), was the most common congenital middle ear abnormality found to be associated with PLF in children.

Adolescent↗
PubMed1993

Three-dimensional CT of the middle ear and adjacent structures.

Three-dimensional (3D) computed tomography of the middle ear and adjacent structures has been carried out in two cadaveric heads from axial and coronal high-resolution images. The structures shown on the images of the walls of the tympanic cavity are illustrated. The usefulness and limitations of the technique, in this region, are discussed: use of grey level volumes at the surface of the slices and the inclusion of structural landmarks is emphasized. The 3D representations show the anatomical spacial relationships of the small structures in and around the middle ear to advantage. The information may be of use in surgical orientation.

Cochlea↗
PubMed2004

Animal ototoxicity of topical antibiotics and the relevance to clinical treatment of human subjects.

OBJECTIVE: The objective of this study was to systematically review the literature on animal ototoxicity from ototopical medications. A secondary objective was to assess the relevance of animal data to the use of ototopical drops in clinical situations involving humans. STUDY DESIGN: We performed a MEDLINE search of the published literature using appropriate search terms to identify pertinent articles, which were reviewed, summarized, and tabulated. RESULTS: One hundred seventy-three articles were reviewed; 61 articles were appropriate to the study question and were further analyzed. CONCLUSIONS: Virtually all studies demonstrate that aminoglycoside antibiotics, when applied topically into the middle ear space, are ototoxic in experimental animals.

Administration, Topical↗
PubMed1994

Postoperative recurrence of perilymphatic fistulas.

Postoperative follow-up study of perilymphatic fistulas (PLFs) showed that recurrence of PLF was not rare and revision was sometimes needed to relieve the symptoms associated with leakage of perilymph. Of the 54 PLF patients surgically treated in our clinic, some sign or symptom of recurrence was found in 9 cases (17%). Vertigo accompanied by spontaneous or positional nystagmus was noted in all 9 cases, while only 3 complained of exacerbation of the existing hearing loss. Revision was indicated in 3 patients since they had no predisposition to spontaneous healing. Various etiological and underlying factors contributed to the incidence of recurrence. Careful operative procedures together with strict postoperative management are required for surgical treatment of PLF.

Adolescent↗
PubMed1986

Two emerging perilymph fistula "syndromes" in children.

This paper proposes two relatively common "syndromes" seen in children with perilymph fistulas using illustrative case reports. One, a 2 1/2-year-old child with bilaterally symmetric progressive sensorineural hearing loss, was found to have bilateral oval and round window fistulas. The other was a child who presented originally with an unexplained unilateral sensorineural loss. It was only when hearing deteriorated in the opposite ear several years later that a perilymph fistula was suspected and confirmed by tympanotomy. The clinical presentations and other details of these cases diverge widely, but may represent two emerging syndromes of perilymph fistulas in children: 1. a congenital or hereditary predisposition, and the other, 2. sudden hearing loss in the "good" ear of children with an unexplained sensorineural hearing loss in the opposite ear.

Audiometry↗