Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Round Window, Ear”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed2000

["Inner perilymph fistula" of the anterior semicircular canal. A new disease picture with recurrent attacks of vertigo].

In 1998 Minor et al. described a new variant of perilymphatic fistula: the "superior canal dehiscence syndrome". This syndrome is clinically characterized by recurrent attacks of vertigo and oscillopsia induced by loud noises or stimuli that result in changes in intracranial or middle ear pressure. It is caused by a dehiscence of bone overlying the superior (anterior) semicircular canal. Due to this dehiscence, a third, mobile window (in addition to the round and oval windows) is formed, and changes in pressure are pathologically transduced to the anterior semicircular canal. Although the superior canal dehiscence syndrome is not a rare condition, no other cases have yet been reported. Therefore, we describe a typical patient who suffered for many years from recurrent attacks of vertigo and oscillopsia induced by coughing and Valsalva's maneuvers. High resolution temporal bone CT scan showed a defect in the bone overlying the left anterior semicircular canal. Three-dimensional eye movement recordings using the search coil technique and subsequent vector analysis demonstrated that the eye movements were induced by excitation of the left anterior semicircular canal. We conclude that superior canal dehiscence syndrome is an important differential diagnosis in patients suffering from symptoms of a perilymphatic fistula, especially since it can be successfully treated by "plugging" of the affected semicircular canal. Such patients are thus spared unnecessary surgery of the middle ear.

Diagnosis, Differential↗
PubMed2001

Perilymphatic fistula.

A perilymph fistula is an abnormal connection between the inner and middle ear that allows escape of perilymph fluid into the middle ear compartment. The clinical symptomatology that follows leakage of fluid is by and large indistinguishable from a number of other pathologies that affect inner ear function. Definite diagnostic proof of a perilymph fistula remains elusive, and methods of diagnosis remain controversial. Traumatic tears in the oval or round windows remain a major cause of perilymph fistula, yet an index of suspicion in traumatic brain injury frequently remains low. The diagnosis of perilymph fistula must always be considered in the appropriate clinical setting of head trauma, barotrauma, and in patients with unresolved and undiagnosed episodes of recurrent vertigo or hearing loss. Surgical treatment with patching of oval and round windows remains the mainstay of therapy for this condition.

Cochlear Aqueduct↗
PubMed2000

Speech evaluation of partially implantable piezoelectric middle ear implants in vivo.

OBJECTIVE: Cochlear microphonic responses (CMs) were measured in a rabbit model in the intact ear (CM1) and in ears with a partially implantable piezoelectric middle ear implant (P-MEI) (CM2) to investigate the characteristics of speech transmission of the P-MEI in vivo. DESIGN: The spectra of pure tones, voices, and elicited CM1 and CM2 obtained from the round window before and after the implantation of a P-MEI device were calculated by using fast Fourier transform. Frequency response functions of CM1 and CM2 were used to demonstrate the functional similarity between the implanted P-MEI and the normal ossicular chain. The coherence functions between the voices and CM1 and between CM1 and CM2 were evaluated to characterize speech transmission of the P-MEI in vivo. Ten rabbit ears were used in this study. Pure tones, six Chinese vowels, and six Chinese characters were the acoustic stimuli. The CMs elicited by a list of bisyllabic words were tape-recorded and then recognized by subjects with normal hearing. RESULTS: Using pure tones at the same intensity of 90 dB SPL, frequency response functions of the CMs between the two states (the intact ear with normal hearing and ears with a P-MEI device at the medium volume) were calculated showing great resemblance in shape. Compared with that at 1 kHz, gain factors were 10 and 20 dB, respectively, at higher frequencies. The correlation and spectral analyses of the vocalizations, CM1 and CM2, demonstrated that the harmonics of CM1 were approximately identical as those of the voices between 0.5 and 5.0 kHz with coherence functions of about 0.7 to approximately 1 at the formants' frequencies, whereas the harmonics of CM2 between 0.5 and 2.5 kHz were enhanced with the coherences near to unity at the formants' frequencies, and others <0.5 kHz and >2.5 kHz were attenuated. The recognition score of the CMs elicited by a list of bisyllabic words was >90% using subjects with normal hearing. CONCLUSIONS: Data from this study suggest that cochlear microphonic potentials can be used as an important tool to evaluate objectively whether the implantation of a P-MEI device is successful and whether the quality in speech transmission of the P-MEI is satisfactory. Thus, the method would be of significance to clinically ascertain the performance of the device in vivo.

Animals↗
PubMed1995

Idiopathic perilymphatic fistulas. A temporal bone histopathologic study with clinical, surgical, and histopathologic correlations.

OBJECTIVE: To report a case of idiopathic perilymphatic fistulas diagnosed and successfully treated during life and confirmed histopathologically post mortem. METHODS: Perilymphatic fistulas were diagnosed clinically and repaired surgically. Light microscopic histopathologic studies were made of both temporal bones after death. RESULTS: Vestibular symptoms had improved postoperatively. Postmortem histopathologic examination of the temporal bones demonstrated patencies of the labyrinth capsule that had been predicted clinically during life, the qualities of the membranous labyrinth in both the operated-on and the unoperated-on ears, and the elements of the surgical repair. Notably, there was no evidence of endolymphatic hydrops. CONCLUSIONS: The histopathologic findings document the relationships of the fistula ante fenestram and the fissure connecting the round window niche and the posterior semicircular canal to idiopathic perilymphatic fistulas. Also, the diagnostic features reported herein allowed this patient with fluctuating hearing loss, episodic vertigo, and tinnitus to be distinguished from a patient with Meniere's syndrome. These findings have implications regarding past and future studies of vestibular and cochlear disorders.

Aged↗
PubMed2002

Ossicular fixation caused by bone dust after saccus decompression surgery.

HYPOTHESIS: To highlight the clinical and histologic features of ossicular fixation produced by bone dust during mastoid surgery. BACKGROUND: Bone dust deposition in the middle ear may occur during temporal bone surgery, but the ossicular fixation that may result from it remains underreported. METHODS: A case is reported of delayed conductive hearing loss after saccus decompression surgery resulting from ossicular fixation by bone dust deposition. RESULTS: Six months after the initial surgery, the patient experienced a 45 dB conductive hearing loss. The findings on second-look tympanotomy were stapes fixation and round window niche occlusion by newly formed tissue. Histologic examination of the latter showed fibrosis and new bone formation in reaction to particles of bone dust. New bone formation is a frequent concomitant of fibrosis in the middle ear and is probably not a growth from the bone dust. CONCLUSION: The use of high-speed drilling of bone in temporal bone surgery carries the risk of bone dust particle deposition in the middle ear. Measures are discussed that can be used to prevent this complication.

Audiometry, Pure-Tone↗
PubMed1978

Tympanic membrane perforations in cats: configurations of losses with and without ear canal extensions.

In cat, a small tympanic membrane (TM) perforation produces a low-frequency loss--in terms of sound pressure changes (deltaSP) in front of the TM re a 10-micronV round window cochlear microphonic (RW CM)--that varies inversely with frequency at a rate of 12dB/octave with a surgically shortened external auditory meatus (EAM). Losses were determined at the outer opening (deltaSP00) and at the TM (deltaSPTM) of four artificial EAM's of various lengths, volumes, and leakiness. In the low-frequency region, a leaky EAM produced a flat loss. In the midfrequency region, the flatness of losses was attributable to (1) the length of the EAM and (2) the location at which the loss was determined. EAM volume was not related to the configuration of the loss. Losses, under all conditions, were always identical in shape and magnitude for the open and closed systems. Clinically, hearing losses due to TM perforations are essentially frequency independent, especially in the low frequencies. The relation between voltage changes (deltaV) across the transducer and losses with different EAM's suggests that the discrepency between audiometric results and CM losses--at least in the high and midfrequencies--may be due to the use of precalibrated SPL's in clinical audiometry.

Acoustic Impedance Tests↗
PubMed1998

Faster recovery in central than in peripheral auditory system following a reversible cochlear deafferentation.

Included among the exciting findings in auditory neuroscience are (i) central plasticity after peripheral injury and (ii) regeneration of auditory nerve fibres following excitotoxic damage. The present study extends our understanding of auditory system plasticity by examining changes in peripheral and central physiology as the cochlea recovers from temporary deafferentation due to excitotoxicity. Application of kainic acid (60 mM) to the round window membrane substantially depressed responses from both auditory nerve and brain stem (inferior colliculus), without affecting distortion-product otoacoustic emissions from the inner ear. The auditory nerve input/output functions recovered over a 30-day period whereas recovery of brainstem response amplitudes occurred within five days. In contrast to amplitudes, thresholds at both peripheral and central levels recovered simultaneously, within five days after kainic acid application. The results indicate that (i) cochlear afferent neurons can recover after excitotoxic damage; (ii) response threshold itself, either central or peripheral, is not sufficient to assess the integrity of the auditory periphery; (iii) the central auditory system can recover more rapidly than the periphery; and (iv) the system can maintain its function in the normal range as peripheral function continues to improve.

Action Potentials↗
PubMed2004

Characterization of a new mouse mutant, flouncer, with a balance defect and inner ear malformation.

HYPOTHESIS: Balance anomalies are often associated with abnormalities of the vestibular part of the inner ear. We studied a newly generated mouse mutant with balance defects and asked whether its behavioral anomalies were associated with inner ear defects. Furthermore, we asked whether the mutation responsible for the defects was located in the same region of mouse chromosome 4 as several other mouse mutations that we have previously described. BACKGROUND: Phenotypic and genotypic analysis of mouse mutants with hearing or balance problems has helped greatly with the identification of the genes involved in deafness and has contributed to the understanding of mechanisms of normal hearing and balance. This article describes a new mouse mutant, flouncer, that shows a balance defect. The flouncer mutation shows semidominant inheritance, and was generated by mutagenesis using N- ethyl-N- nitrosourea. METHODS: Hearing was assessed by the Preyer reflex (ear-flick) test. Behavioral tests including open field and swimming tests were performed. The morphology of the middle and inner ears was investigated by microdissection, clearing using glycerol, paint-filling of the labyrinth, and scanning electron microscopy. RESULTS: Flouncer mutants showed vestibular dysfunction but do respond to sounds. Phenotypically, mutants had various degrees of truncation of the lateral semicircular canals, small or obliterated round window of the cochlea, and mild morphologic anomalies of the stapes. Flouncer mutants showed circling behavior and hyperactivity. Linkage mapping using a backcross has indicated that the mutation lies in proximal chromosome 4 proximal to D4Mit171. CONCLUSION: The lateral semicircular canal has been described to be the most commonly affected part of the inner ear in humans, and flouncer provides a mouse model for genetic and developmental analysis of such defects.

Animals↗
PubMed1992

[Effects of inner ear immune responses on auditory function in guinea pigs].

Following direct challenge with KLH antigen primary or secondary (after systemic immunization) to the ES (endolymphatic sac) in guinea pigs, ECoG (electrocochleograms) were recorded from the round window induced by click and tone pips. The recordings were carried out on the 2nd, 7th and 21st days after local antigen challenge. There were no abnormal findings in the ECoG of the primary antigen challenged animals. On the other hand, prolongation of latencies, decrease in amplitudes of APs (compound action potentials) and increases in SP/AP ratios were observed in the 2nd day recordings of the secondary antigen challenged animals. However, all parameters of ECoG in the 7th day recordings were normal. Decreases in AP amplitudes were again found in the 21st day recordings. The ECoG findings with click and tone pip stimulation showed similar results. From these findings, in conjunction with morphological observations, it is speculated that these ECoG findings are caused by immuno-injury to the ES and cochlea, as well as the resultant endolymphatic hydrops which develops acutely and gradually subsides after secondary challenge.

Animals↗
PubMedDate not supplied

Endotoxin-induced otitis media with effusion in the mouse. Immunohistochemical analysis.

A model of endotoxin-induced otitis media with effusion was developed in healthy BALB/c mice. Endotoxin extracted from Salmonella typhimurium (10 micrograms/ml) was injected into the middle ear bulla transtympanically and the resultant inflammatory response was analyzed using immunohistochemical methods. Serous effusions were observed otoscopically and mucosal edema and infiltrate were studied histologically, both peaking at 3 days and essentially resolving by 7 days. However, persistence of a small area of inflammation in the round window niche was consistently present at 2 weeks. The specific cellular responses to endotoxin were analysed by histologic and immunohistologic examination of the murine temporal bone. We used antibodies to identify T-lymphocytes (anti-Lyt-1, -Lyt-2), macrophages and neutrophils (anti-Mac-1), and immunoglobulins (anti-IgA, -IgG, -IgM). In the mucosal/submucosal infiltrate Mac-1+ and Lyt-1+ cells peaked from days 1 to 3. Within the luminal effusion Mac-1+ and Lyt-1+ cells as well as diffuse (not cell-associated) IgG, IgM, and IgA staining were most prevalent from days 1 to 3, while IgG-bearing plasma cells formed the majority of the luminal cells observed at 1 to 2 weeks. No significant influx of T-suppressor cells was observed at any time. The round window niche and anterior portion of the tympanic bulla mucosa were found to be the most reactive areas. These results suggest that endotoxin alone is capable of producing an inflammatory infiltrate in the mouse consistent with otitis media with effusion, and that the interaction of endotoxin with resident immunocytes of the middle ear, as well as serum derived immune cells, is consistent with the known phlogistic properties of endotoxin.

Animals↗
PubMed2002

Steroid perfusion of the inner ear for sudden sensorineural hearing loss after failure of conventional therapy: a pilot study.

The aim of this study was to determine if high-dose delivery of methylprednisolone to the round window can improve hearing after the failure of conventional treatment for sudden sensorineural hearing loss (SSHL). In 6 patients with SSHL an Intraear microcatheter was placed in the round window niche and methylprednisolone (62.5 mg/ml) was infused at a rate of 10 microl/h for 8-10 days. Audiometric assessments (including measurement of speech discrimination) were made at presentation, either every day or every other day during treatment and 5 days after the completion of perfusion. Perfusion of methylprednisolone was beneficial for all 6 patients, with a 16.25-25 dB improvement in hearing threshold. A dramatic improvement in speech discrimination was also noted in all patients. In conclusion, methylprednisolone perfused at the level of the round window membrane resulted in significant recovery of hearing function after the failure of standard treatment of SSHL.

Administration, Topical↗
PubMed1989

Rapid assessment of sound-evoked olivocochlear feedback: suppression of compound action potentials by contralateral sound.

The compound action potential (CAP) measured at the round window of anesthetized cats in response to low-level tone pips can be significantly suppressed by addition of tones or noise to the opposite ear. This contralateral-sound suppression disappears upon transection of the olivocochlear bundle. The frequency and level dependence of the suppression phenomenon are well explained by known sound-evoked discharge properties of single olivocochlear neurons. Thus, the contralateral-sound suppression of cochlear CAP should prove useful as a rapid measure of the magnitude of the sound-evoked efferent feedback to the cochlea.

Animals↗
PubMed1996

Effects of kainic acid on the cochlear potentials and distortion product otoacoustic emissions in chinchilla.

In absence of acoustic stimulation, the auditory nerve generates electrical noise with a spectral peak between 300 and 3000 Hz (Dolan et al., 1990). This electrical noise is eliminated when the dendrites of auditory nerve fibers are damaged by kainic acid (KA). We hypothesized that the KA-induced damage to the afferent dendrites might alter cochlear micromechanics or modify outer hair cell (OHC) electromotility. The KA-induced decrease in spontaneous electrical noise from the auditory nerve could conceivably reduce the spontaneous sounds recorded in the ear canal and the postulated change in cochlear micromechanics might alter distortion product otoacoustic emissions (DPOAE). To evaluate these hypotheses, we applied KA to the round window of the cochlea. KA reduced the spontaneous electrical noise recorded from the round window and significantly reduced the amplitude of the compound action potential (CAP) to tone bursts at 2, 4 and 8 kHz. KA caused only a slight reduction in the amplitude of the cochlear microphonic (CM) recorded from the round window: however, it had no effect on the spontaneous acoustic noise in the car canal or on 2 f1-f2 DPOAEs. These results suggest that the KA-induced reduction of electrical noise from the auditory nerve has no measurable effect on OHC electromotility as reflected in spontaneous otoacoustic emissions and that damage to the afferent dendrites has no effect on cochlear micromechanics as reflected in DPOAEs.

Acoustic Stimulation↗
PubMed2001

Mutant beta-spectrin 4 causes auditory and motor neuropathies in quivering mice.

The autosomal recessive mouse mutation quivering (qv), which arose spontaneously in 1953, produces progressive ataxia with hind limb paralysis, deafness and tremor. Six additional spontaneous alleles, qvJ, qv2J, qv3J, qv4J, qvlnd and qvlnd2J, have been identified. Ear twitch responses (Preyer's reflex) to sound are absent in homozygous qv/qv mice, although cochlear morphology seems normal and cochlear potentials recorded at the round window are no different from those of control mice. However, responses from brainstem auditory nuclei show abnormal transmission of auditory information, indicating that, in contrast to the many known mutations causing deafness originating in the cochlea, deafness in qv is central in origin. Here we report that quivering mice carry loss-of-function mutations in the mouse beta-spectrin 4 gene (Spnb4) that cause alterations in ion channel localization in myelinated nerves; this provides a rationale for the auditory and motor neuropathies of these mice.

Animals↗
PubMedDate not supplied

Labyrinthitis ossificans due to chronic otitis media.

Histopathology of two cases of unilateral labyrinthitis ossificans in the presence of bilateral chronic suppurative otitis media is presented. In both cases, ossification and fibrosis were limited to the scala tympani of the lower basal turn, apparently due to inflammation entering through the round window membrane. The round window was occluded by new bone and fibrous tissue presumably resulting in a conductive hearing loss in addition to the conductive loss due to middle ear lesions. Degeneration of the hair cells of the organ of Corti was limited to the lower basal turn where ossification and fibrosis occurred.

Adult↗
PubMed1994

Stapedotomy with stapedius tendon preservation: technique and long-term results.

From 1975 to 1992, a total of 1459 primary stapedoplasty operations (i.e., stapedectomy, stapedotomy with tendon section, and stapedotomy with tendon preservation) were performed in 1323 subjects at the Ear, Nose, and Throat Department of the University of Verona. Pure-tone audiometry was carried out in all subjects who were operated on and who underwent 6-month and 10-year follow-ups. To evaluate the influence of stapedius tendon preservation on functional outcome, we randomly selected subgroups of patients using the three different stapedioplasty techniques and tested them by multiple-frequency tympanometry, psychoacoustic tuning curves, and speech discrimination in noise. Finally, to assess the effect of prosthesis diameter on middle ear transfer function, we used the electrocochleographic technique and examined the threshold and latency of cochlear nerve compound action potentials recorded during surgery from the round window. The results of this study show that the best auditory performance in otosclerotic subjects is achieved by performing a stapedotomy of 0.7 mm diameter, using a 0.6 wire-Teflon piston, and preserving the stapedius tendon.

Acoustic Impedance Tests↗
PubMedDate not supplied

Vestibular function and cochlear implant.

The authors illustrate their personal experience relating to 32 patients, aged between 12 and 74 years, undergoing cochlear implant, in whom vestibular reflexes were evaluated before and after surgery. This series did not include cases of areflexia, but only 1 case of reduced vestibular reflexia consequently to surgery. In this case, owing to the probable intervention of central compensation processes, labyrinthine hyporeflexia never became clinically significant. These personal results enable the authors to affirm that preoperative vestibular reflexes do not offer elements able to influence the choice of the ear in which to perform the cochlear implant. In the series of patients reported by the authors, a cochleostomy by removal of the floor of the round window niche, following the suggestions of O'Leary et al., always headed the electrode implant. This contrivance may reduce or eliminate the negative effects on vestibular receptors indirectly caused by the consequent and inevitable alteration of perilymph pressure produced by the implant.

Adolescent↗
PubMedDate not supplied

A study of tea tree oil ototoxicity.

Tea tree oil shows promise as an effective treatment for a number of micro-organisms commonly associated with otitis externa and otitis media, but its possible ototoxicity has not been previously assessed. The ototoxicity of tea tree oil was examined in the guinea pig by measuring the thresholds of the compound auditory nerve action potential (CAP) to tone bursts before and after instillation of the oil into the middle ear. After 30 min of instillation, 100% tea tree oil caused a partial CAP threshold elevation at 20 kHz. A lower concentration of oil [2% tea tree oil dissolved in saline using 0.5% detergent (Tween-80)] did not cause any significant lasting threshold change after middle ear instillation for the same period of time. The latter concentration of oil is greater than the minimum inhibitory concentration reported for most micro-organisms in the effective spectrum of the oil and this suggests that this concentration may be safe and effective provided only short exposures (about 30 min) are used. The results suggest that high concentrations of tea tree oil applied to the round window for a relatively short time are to some extent ototoxic to the high-frequency region of the cochlea. Hence further study is needed to establish whether tea tree oil can be used with safety in the treatment of external and middle ear infections.

Animals↗