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Results for “Round Window, Ear”

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At least 145 records · Page 8Linked to original sources
PubMed1996

[Blood patch therapy of the perilymphatic fistulas--an experimental study].

Blood patch is a therapeutic procedure that uses a perilymphatic fistula to repair an inner ear window rupture by filling the tympanic cavity with autologous blood. The experimental study was conducted in 13 guinea pigs. Autologous blood or commercially available fibrin glue was poured into the otic bulla after artificial rupture of the round window. The animals were sacrificed immediately, or 1 to 7 days after the operation. The results showed that the blood or the fibrin glue successfully closed the window rupture by closing directly and by facilitating the formation of granulation at the margin of the rupture. Fibrin glue seemed to be preferable to autologous blood due to its non-toxic nature in the inner ear.

Animals↗
PubMedDate not supplied

An experimental study of inner ear pathology due to NaCl on the round window.

An animal experiment was performed to evaluate structural and ultrastructural changes to the inner ear as a result of placing 3-4 crystals of reagent grade sodium chloride (NaCl) on the round window membrane. Chinchillas were sacrificed at 8 and 24 hours after treatment and the cochlear and vestibular tissues were examined by light microscopy and scanning electron microscopy. Inner ear pathology consisted of destruction of both sensory and supporting cells in the basal turn of the organ of Corti, atrophy of the stria vascularis and alterations to the otoconia and the maculae and ampullae of the vestibular system. This study demonstrates that NaCl in the middle ear does not provide a model for Meniere's disease as previously suggested by Arslan. It may, however, be utilized in the destructive treatment of selected inner ear disorders.

Animals↗
PubMed1981

Surgical anatomy and pathology of the round window.

A study of the surgical anatomy and pathology of the round window was performed on a total of 292 serially sectioned temporal bones. The surgical approach to the round window is discussed with consideration of the anatomical findings. In the pathological study obliteration of the round window niche occurred as a congenital anomaly, in otosclerosis, chronic otitis media and as an end result in suppurative labyrinthitis. Clinical reports seem to indicate that obliteration of the window is associated with significant hearing loss, contrary to the findings in experimental animals. In chronic otitis media the round window is a pathway for spread of infection to the labyrinth, but also the finding of perilymphatic precipitates to the window in some ears suggests that certain inflammatory products may enter the scala tympani through the round window and so lead to high tone sensorineural hearing loss.

Adolescent↗
PubMed1984

Notes on the comparative mechanics of hearing. I.A shock-proof ear.

In woodpeckers, the cochlear windows show functional specialization. The small membrane of the round window is attached to a special bony plate of the columella. This arrangement of coupled windows probably increases power dissipation at the fenestral boundaries and so dampens impulsive mechanical disturbances.

Animals↗
PubMed1992

Bacterial tympanogenic labyrinthitis, meningitis, and sensorineural damage.

Pathologic changes (sensorineural hearing loss, labyrinthitis, meningitis) can follow otitis media. Various macromolecular substances demonstrably enter the inner ear via the round window membrane, but its permeability to bacteria is less known. We inoculated Streptococcus pneumoniae type 7F bilaterally into the middle ears of two groups of chinchillas, with and without grafted round window membranes. Inner ears of inoculated animals were observed by light and electron microscopy. None with continuous grafts had labyrinthitis. Bacteria penetrated all three layers of nongrafted round window membranes and into all cochlear turns, entering Schuknecht's channels and following neuronal pathways; nerves were often degenerated, hair cells were damaged or missing, and the stria vascularis was edematous and hemorrhagic. The neural damage suggests a mechanism for the hearing loss that can follow otitis media. Absence of labyrinthitis and meningitis in grafted animals suggests a tympanogenic pathway for the bacteria.

Animals↗
PubMed1992

Middle-ear transmission: acoustic versus ossicular coupling in cat and human.

Otologic surgeons consider the action of sound pressure on the cochlear windows to be of major importance in certain cases of middle-ear pathology, yet previously published network models of mammalian middle ears do not include such a mechanism. A unified middle-ear model is developed in which it is assumed that the difference of acoustic pressures acting on the windows adds to the ossicular-chain pressure to produce cochlear input. From a network model of the cat middle-ear cavities we estimate the contributions of pressures on the cochlear windows for both normal and abnormal cat ears. For the human ear we use the model of Kringlebotn (1988) and measurements of Békésy (1947). We determine that the pressure difference across the cochlear windows is negligibly small in normal cat and human ears. Thus, it is a reasonable approximation to ignore this mechanism in normal ears. For ears with a drastically altered tympanic membrane and/or ossicular chain, acoustic coupling to the cochlear windows can--to a considerable extent--explain residual hearing in human. The model predicts hearing levels for type IV tympanoplastic reconstructions that agree with the best results obtained surgically.

Acoustic Stimulation↗
PubMedDate not supplied

Effect of experimentally induced otitis media on cochlear implants.

Cat cochleas implanted with scala tympani prostheses were investigated histologically after inoculating the bullae with a suspension of group A streptococci. The prosthesis was passed through the round window membrane in one ear. In the other the prosthesis bypassed the round window via an opening anteroinferior to the round window niche. Before death, horseradish peroxidase was administered as a tracer for possible pathways of infection. Results showed that group A streptococci were pathogenic to the cat and caused inflammation in the bulla. The unimplanted round window membrane and the seals around the electrode entry points prevented infection from entering the cochlea. The seals around electrodes inserted either through the round window membrane or an opening drilled anteroinferior to the niche were equally effective. The horseradish peroxidase tracer studies showed, however, that a gap existed between the electrode and membranous seal, and this could be a potentially vulnerable site under certain conditions. Drilling an anteroinferior opening into the cochlea resulted in bony sequestra entering the cochlea. This can be avoided by blue-lining the opening and removing bone with picks before making an opening through the endosteum.

Animals↗
PubMed1994

Perilymphatic fistula with no visible leak of fluid into the middle ear: a new method of intraoperative diagnosis using electrocochleography.

A new method for the intraoperative diagnosis of a perilymphatic fistula is presented. Two cases are reported in which the test clearly indicated the presence of a fistula even though no visible leak of fluid was noted by the surgeon. In each case, there was a clear history of vertigo and hearing loss. Preoperatively, the presence of a perilymphatic fistula was suggested using raised intrathoracic pressure test in electrocochleography (ECochG). During the surgery, there was no visible leak of fluid into the middle ear. Electrocochleography was undertaken intraoperatively by placing an electrode in the round window niche and suctioning the oval window area; in neither case was any ECochG change seen. Next the electrode was repositioned on the oval window and when the round window area was suctioned, obvious ECochG changes occurred. Action potential (AP) amplitude dramatically decreased in both cases and summating potential (SP) increased in one case.

Adult↗
PubMed2004

[Treatment of acute cochleovestibular damage after diving].

BACKGROUND: There has been a steady in-crease of recreational scuba divers in the last years. The majority of diving associated diseases involve otorhinolaryngology, the most important of which are cochleovestibular dysfunctions as these can lead to permanent inner ear failure. MATERIAL AND METHODS: We discuss the origin and clinical symptoms, as well as the therapy, of both inner ear barotrauma and inner ear decompression illness. Our own experiences are considered together with a review of the literature from the last decade. RESULTS: Inner ear decompression illness seems to be a relatively common diving associated incident and is not as rare as previously thought. DISCUSSION: Hyperbaric oxygen therapy is the treatment of choice for patients with inner ear decompression sickness, but is contraindicated in patients with inner ear barotrauma. As long as an inner ear decompression illness can not be ruled out, we suggest that every patient should be treated using hyperbaric oxygen therapy but only after bilateral paracentesis.

Barotrauma↗
PubMed1994

Modulation of the hair cell motor: a possible source of odd-order distortion.

A recent paper by Nuttall and Dolan [J. Acoust. Soc. Am. 93, 2061-2068 (1993)] on intermodulation distortion in the cochlea concluded that electrical quadratic distortion (f2-f1) came predominantly from inner hair cells (IHCs). However, they suggested that the outer hair cells provided the mechanical input that caused this even-order distortion. The data reported here describe the nonlinear components in the gross electrical and acoustic emission responses of the gerbil and suggest a mechanism by which odd-order distortion could be generated by modulation of the fast phasic motile response of outer hair cells (OHCs) by the even-order distortion signal.

Acoustics↗
PubMed1991

Otitis media. 16 years of pathogenesis approach.

The authors describe 16 years of their approach to research in otitis media, their rationale, and the concepts that have evolved from their experiments and clinical work. The authors suggest that interest is the key to progress and not laboratory facilities. They extend an invitation to individuals with different backgrounds but common interest in otitis media to work together from the standpoint of pathogenesis.

Animals↗
PubMed1995

Effects and management of barometric change on cavities in the head and neck.

Changes in atmospheric pressure may result in barotrauma to a variety of head and neck structures including the middle and inner ears, the sinus cavities, the teeth and some cranial nerves. This article outlines the pathophysiology of these injuries and suggestions are offered for prevention and treatment.

Atmospheric Pressure↗
PubMed1975

Rupture of the round window membrane.

A perilymph leak into the middle ear through a ruptured round window membrane results in the symptoms of hearing loss, tinnitus and vertigo, either singly or in combination. The case histories of thirteen patients with such a fistula are described, these patients having in common a predisposing incident which had led to a rise of C.S.F. pressure. Symptomatology and the results of investigation are analysed and operative technique and results discussed. While it appears that vertigo uniformly responds very satisfactorily to operative treatment the improvement in hearing loss and tinnitus is more difficult to predict.

Adolescent↗
PubMed2000

Rupture pressures of membranes in the ear.

The rupture pressures of the tympanic membrane, Reissner's membrane, the round window membrane, and the annular ligament have all been measured in cadaver ears from Norwegian cattle. For the tympanic membrane, a static overpressure was applied to the ear canal; for Reissner's membrane, to the endolymph; and for the round window membrane, to the perilymph. The rupture pressure of the annular ligament equals the rupture force to the footplate divided by the area of the oval window. The mean rupture pressures are 0.39 atm for the tympanic membrane, 0.047 atm for Reissner's membrane, greater than 2 atm for the round window membrane, and 29.4 atm for the annular ligament. This last pressure corresponds to 0.68 kilogram force applied to the footplate. The ruptures of the tympanic membrane appeared without exception as small tears in the pars flaccida. The rupture pressure of the tympanic membrane was also measured in a few ears from foxes.

Animals↗