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PubMed1981

[Temporal bone histopathology in a case of trisomy 22-syndrome (author's transl)].

This premature female infant died soon after birth. She had numerous gross anomalies and was found on cytogenic studies to have Trisomy 22. Polytomographic and histologic studies of the left ear revealed multiple anomalies including complete aural atresia, non-pneumatization of the middle ear with a vertical shelf of bone in the mid portion of the middle ear, absence of the stapes and oval window and bony closure of the round window niche. The cochlea is flat in shape and shows one and a half turns with incomplete formation of the modiolus. The intersaccular septum is rudimentary but the spiral ganglion is clearly seen in Rosenthal's canal through the one and a half turns. The organ of Corti is well developed and contains hair cells. The stria vascularis is present. The utricular and saccular maculae as well as all cristae are well developed and contain hair cells. The saccular wall is collapsed onto an atrophic appearing otolithic membrane. The utricle is dilated, the lateral semicircular canal appears short and the bony canal is wide. The flattened and shortened cochlea with deformities of the cochlear duct, and the large vestibule resembles Mondinis dysplasia.

Abnormalities, Multiple↗
PubMedDate not supplied

[The usefulness of computer tomography in planning cochlear implant surgery].

In recent years, technical progress has created new complex acoustic implants which send an electrical stimulus to the eighth cranial nerve through one or more electrodes inserted through the round window into the scala tympani of the cochlea. The abnormal--mostly osteosclerotic--processes which cause deep hearing loss may prevent electrode insertion. Therefore, internal ear anatomy must be detailed, which is essential to assess the feasibility of surgery and, if surgery is indicated, to plan it properly. High resolution CT (HRCT) was performed on 79 patients to study cochlear patency, round window shape and patency, degree of temporal bone pneumatization and the proximity of vascular structures (carotid artery and jugular vein). On the basis of HRCT results, 14 of 79 patients were excluded from surgery. Comparing HRCT with surgical findings, the authors conclude that HRCT is the method of choice to examine the candidates to cochlear implant thanks to its high spatial resolution and excellent depiction of even the smallest structures. Its only limitation is that it fails to assess the lack of patency of the cochlear canal due to fibrosis, which is not associated with demonstrable density changes (3 of 19 surgical patients). This problem may be solved by submitting the potential surgical candidates to MRI.

Adult↗
PubMed1996

Electrically evoked cubic distortion product otoacoustic emissions from gerbil cochlea.

It has been demonstrated that electrical stimulation of the cochlear partition results in basilar membrane vibration and otoacoustic emissions. Electromotility of stimulated outer hair cells (OHCs) elicits the electrically evoked otoacoustic emissions (EEOAEs). Although electrically evoked upper and lower sideband distortion products (DPs) have been reported, electrically evoked cubic DP has not been investigated. Since the acoustically evoked cubic DP is the most commonly used otoacoustic measure of cochlear nonlinearity, this study tested whether electrical stimuli evoke a cubic DP otoacoustic emission. An electrical current containing the frequency component f1 and f2 (f1 < f2) was delivered to the round window niche of the gerbil, and electrically induced sound pressure change in the external ear canal was measured with a microphone. It was found that, in addition to f1 and f2 EEOAEs, cubic DP (2f1-f2) and other emissions at 3f1-2f2, 2f2-f1 and f2-f1 frequencies are electrically evoked. The electrically evoked cubic DP growth is similar to that of an acoustically evoked cubic DP. An electrical stimulus at f1 or f2 and an acoustic stimulus at f2 or f1 produce an identical cubic DP to that evoked by two electrical stimuli and/or two acoustic stimuli at f1 and f2 frequencies. An acoustic suppressor at a frequency near f2 can completely suppress an electrically evoked cubic DP emission. These data demonstrate that DPs can be provoked by a complex two frequency electrical current delivered to the round window niche. These stimuli elicit mechanical vibrations, from stimulated OHCs near the round window, which propagate apically toward their characteristic frequency places on the basilar membrane, and produce combination DPs. Electrically evoked cubic DPs appear to be produced by the same nonlinear mechanism that generates acoustically evoked DPs.

Acoustic Stimulation↗
PubMed1992

Are glucocorticoids in ear drops ototoxic?

Ototopical drugs such as antiseptics, antibiotics and solvents can have an ototoxic potential. These substances are often combined with an anti-inflammatory steroid of which hydrocortisone is one of the most commonly used. Little is known of possible adverse effects on the inner ear of hydrocortisone. From animal experiments it has been shown that this drug applied in the round window niche will impair the ABR thresholds in the high frequency range. The ototoxic potential of glucocorticoids will be discussed and questioned.

Animals↗
PubMedDate not supplied

High-frequency sensitivity of the mature gerbil cochlea and its development.

The thresholds of compound action potentials evoked by tone pips were measured in the cochleae of anesthetized gerbils, both in adults and in neonates aged 14, 16, 18, 20 and 30 days, using round-window electrodes. Stapes vibrations were also measured, using a laser velocimeter, in many of the same ears of adults and neonates aged 14, 16, 18 and 20 days to assess cochlear sensitivity in isolation from middle ear effects and to circumvent problems associated with calibration of acoustic stimuli at high frequencies. Whether referenced to sound pressure level in the ear canal or stapes vibration velocity, thresholds in adults were roughly uniform in the entire range of tested frequencies, 1.25-38.5 kHz. In neonates, thresholds decreased systematically as a function of age, with the largest reductions occurring at the highest frequencies. Thresholds remained slightly immature at all frequencies 30 days after birth. The results for adult gerbils are consistent with the recent finding that basilar-membrane responses to characteristic frequency tones normalized to stapes vibrations are as sensitive at sites near the round window as at more apical sites. The results for neonates confirm that the extreme basal region of the cochlea is the last to approach maturity, with substantial development occurring between 20 and 30 days after birth.

Acoustic Stimulation↗
PubMedDate not supplied

A novel microperfusion system for the long-term local supply of drugs to the inner ear: implantation and function in the rat model.

Local therapy is practiced for middle and inner ear diseases but is usually restricted to cases of ear drum perforation or repeated invasive intratympanic drug application. Perfusion of drugs on the round window or through the scalae of animals using a pump system suggests that the chronic local drug treatment might also be feasible in humans. However, drug delivery systems that are currently on the market involve repeated reimplantation if they are to be used for long-term drug supply. A bone-anchored, totally implantable micro-drug delivery system (MDS) for patient-controlled drug supply has been developed [Lehner et al., 1997]. In this study, we show the first successful long-term in vivo test of the MDS micro-pump in rats. The process of implantation and first functional tests will be described. The biomaterial used to manufacture the delivery system did not cause any inflammation reaction in any of the 9 animals successfully implanted. After activation of the micro-pump, the drug reservoir and port was found to be fluid-tight. Bolus applications of tetrodotoxin (TTX) to the round window induced a transient decrease of evoked brainstem responses. In 2 animals which carried the MDS for more than 8 months the proper functioning of the pumping device was examined in a 2-3 week interval over a 3 month period. The MDS can be autoclaved even after long-term implantation and can then be reused for subsequent implantations. Designed for life-long implantation in humans, the demonstration of an effective long-term drug supply to the inner ear using the MDS provides an encouraging first step towards future long-term drug treatment of the inner ear in humans.

Administration, Topical↗
PubMedDate not supplied

Volume-pressure properties of round and oval windows. A quantitative study on human temporal bone.

A model study was carried out on human temporal bones to assess quantitatively the displacement of the round and oval windows when different pressure levels were applied to the external ear canal and inside the middle ear. It was found that the major displacements of the window membranes occurred in the pressure range of +/- 20 cm H2O in the intact middle ear. An additional increase in the middle ear pressure up to +/- 70 cm H2O caused a minor displacement of the window membranes.

Aged↗
PubMed2001

[The orientation and its significance of water channel protein in the mouse inner ear].

OBJECTIVE: To examine the distribution of various subtypes of water channel protein (aquaporin, Aqp) in various structures of the mouse inner ear. METHODS: Thirty mice with white color were used in this study and were cardiacally perfused. The temporal bones were taken out and were processed and sectioned by paraffin-embedded technique. The sections were labeled with fluorescent antibody by immunohistochemical method. The distribution of Aqp1, 3, 4, 5, 7, 9 were confirmed in the inner ear of mouse. RESULTS: The constant and clear fluorescent reaction could be observed in the inner ear tissue with the first antibody concentration of 1:200 for Aqp-1 and 1:100 for Aqp-3, 7, 9. But the reaction of Aqp-4 and 5 could not be found with the concentration of 1:50, even 1:30. Aqp-1 was labeled in the round window membrane, spiral ligament, endolymphatic sac and duct, utricle and saccule and the wall of inner ear blood vessel; Aqp-3 in the spiral limb, vestibular lip, internal and external sulci, basilar membrane and basilar membrane crest, endolymphatic sac and duct, membranous semicircular canal and utricle and saccular macula; Aqp-7 in the stria vascularis, basilar membrane, Reissner's membrane, utricle and saccule and their maculae; Aqp-9 in the spiral limb, vestibular lip internal and external sulci, Reissner's membrane, membranous semicircular canal, saccule and its macula. CONCLUSION: Aqp-1, 3, 7, 9 were extensively distributed in various tissues of mouse inner ear. Their distribution sites and reaction degree were different, and mainly located in the structures related to the endolymph.

Animals↗
PubMed1976

Round window fistula.

Round window fistula as a cause of sudden hearing loss was diagnosed in five people. It was associated with a sudden change in middle ear pressure in three, with heavy lifing in one, and was probably caused by a significant blast exposure in the other. The clinical features of the condition are varied, with hearing loss and tinnitus being the only constant findings in our patients. One case demonstrates, perhaps for the first time, the association of an abnormally mobile portion of the round window membrane with vertigo and nystagmus. Suggestions on identification and management of round window fistula are made.

Adult↗
PubMed2006

Retrofacial approach of cochlear implantation in inner ear malformation with aberrant facial nerve: a case report.

Cochlear implantation is regarded as a safe surgery for young children with minimal complications. However, inner ear malformations and aberrant course of facial nerves may impede electrode insertion via the round window approach and increase the risk of iatrogenic facial nerve injury. We report a case of cochlear incomplete partition in a patient with anomalous facial nerve anatomy. The anterior and inferior displacement of the facial nerve obscured the round window. A retrofacial approach was used to expose the round window and the electrode was inserted successfully. No surgical complications were found postoperatively, and the child showed significant improvement in speech perception. As the course of the aberrant facial nerve is difficult to track preoperatively, surgeons should proceed with caution to reduce the risk of facial nerve injury during the operation.

Cochlear Implantation↗
PubMed2006

[Treatment of sensorineural hearing loss in acute viral otitis media with intratympanic dexamethasone and hyaluronic acid in comparison with intravenous therapy].

BACKGROUND: Intratympanic dexamethasone with hyaluronic acid has shown to be an effective treatment of the inner ear damage in sudden hearing loss and Menière's disease. It is not known yet if the same applies to the toxic inner ear damage in acute viral otitis media. PATIENTS: Retrospectively, 26 patients who suffered from acute viral otitis media with sensorineural hearing loss were examined with regard to the improvement of their inner ear hearing loss. Twelve patients were treated with intravenous therapy only, consisting of hydroxyethyl starch, pentoxifylline and prednisolone. Fourteen patients additionally received intratympanic injections, consisting of dexamethasone and hyaluronic acid once acute inflammatory changes subsided. The inner ear hearing loss was evaluated by means of standard bone-conduction audiometry. RESULTS: Neither local nor systemic side effects of the intratympanic injections occurred. During treatment no significant difference in the improvement of bone-conduction thresholds in any frequency was seen between the two groups. CONCLUSIONS: Intratympanic injections of dexamethasone with hyaluronic acid do not result in any additional benefit on the sensorineural hearing loss in acute viral otitis media compared to intravenous therapy alone. A reason might be the post inflammatory changes of the round window membrane or the toxic nature of the acute viral infection affecting the inner ear.

Acute Disease↗
PubMed1993

The postnatal growth of the temporal bone and its implications for cochlear implantation in children.

The postnatal growth of the human temporal bone was examined by direct anatomical measurements on 60 cadaver specimens of all ages. The bones were dissected as one would perform cochlear implant surgery using a posterior tympanotomy approach. Nineteen anatomical/surgical landmarks with implications for cochlear implant surgery were identified on each bone and the distance between these points measured. The temporal bone was found to be a complex structure, phylogenetically, anatomically and functionally consisting of four different parts with independent postnatal development. The inner and middle ears were adult size at birth. The external auditory canal and most parts of the temporal bone were subject to significant lateral growth. The size of the pneumatised mastoid increased in all directions. In the facial recess, however, no postnatal growth was observed. Between birth and adulthood an average of 12 mm (SD 5 mm) of growth was seen directly between the sino-dural angle and the round window, the landmarks approximating the implantation site for the receiver-stimulator and the electrode entry point into the inner ear. However, if an electrode leadwire is fixed at a cortical fixation site such as the posterosuperior point of Macewen's triangle, the leadwire would be subject to approximately 20 mm of growth. These results indicate that a paediatric cochlear implant design incorporating an expandable leadwire to accommodate this growth should allow up to 25 mm of leadwire lengthening. The fossa incudis showed no growth relative to the round window and was found to be a convenient fixation site for the electrode array close to the cochlea. From an anatomical and surgical point of view, cochlear implantation in very young children is feasible, provided the electrode array is secured and the design accommodates for controlled leadwire lengthening.

Adolescent↗
PubMed1994

Otitis media (silent): a potential cause of childhood meningitis.

Sixteen temporal bones from 8 infants with otitis media, who died of meningitis, and 6 controls from infants with only otitis media, were studied histologically. All bones contained middle ear effusion and residual mesenchyme, but, unlike the controls, the meningitic cases showed considerable histopathological tissue changes of chronic and acute otitis media and chronic inflammatory cells in the round window membrane and within the perilymph, the modiolus, and the cochlear aqueduct, suggesting the latter as likely portals from the inner ear to the meninges. Since all tympanic membranes were intact and 3 were histologically normal, this silent route of infection warrants medical vigilance.

Acute Disease↗
PubMedDate not supplied

Mondini's deafness. A review of histopathology.

From a histopathological survey of 12 ears (7 cases) of Mondini's deformity and deafness, the following conclusions or interpretations are drawn: 1) Mondini's bony deformity diagnosable by polytomography does not necessarily indicate Mondini's deafness or x-ray diagnosis of Mondini's deafness cannot be specifically relied upon. 2) The pars superior (semicircular canals and utricle) may be absent (aplastic) or the canals may be enlarged leading to interesting questions regarding vestibular physiology in such patients. 3) Enlarged endolymphatic duct and deficient utriculoendolymphatic valve are commonly found associated with absence of endolymphatic hydrops or collapse suggesting an operational longitudinal flow. 4) One and one-half or fewer (instead of 2 1/2) cochlear turns are characteristic; however, end-organ of Corti lesions (aplasia) may be present or absent leading to interesting speculations for further research regarding auditory function, especially in those cases with normal-appearing sensory structures. 5) Mechanisms of hearing loss in Mondini's deafness can be variably explained on the basis of inner ear or middle ear pathology including dysgenesis of the end-organs and associated neural elements sufficient to cause sensorineural hearing loss, aplasia of the oval or round windows which might explain manifest "sensorineural hearing loss" in the presence of normal-appearing organs of Corti and aplasia or infection of the middle ear causing a conductive loss which can be superimposed upon a sensorineural hearing loss.

Aged↗
PubMed2000

Effects of middle ear pressure changes on clinical symptoms in patients with Ménière's disease--a clinical multicentre placebo-controlled study.

Different medical and surgical methods have been tried in attempting to reduce endolymphatic pressure in Ménière's disease. Pressure treatment has a role on the treatment staircase, after pharmacological treatment and before destructive methods. Pressure chamber treatment has shown that some patients respond well to the treatment with diminishing inner ear symptoms and also some hearing improvement. Earlier studies have shown that electrocochlear measurements improve after local pressure treatment in the ear. The present study was a prospective randomized placebo controlled, multicentre clinical trial. 56 patients with active Ménière's disease, age 20-65 years, with a hearing loss of 20-65 dB PTA participated. A total of 31 patients completed 2 weeks use with an active apparatus (Meniett) and 25 patients completed the 2 weeks with the placebo gadget. Both machines were produced by Pascal Medical, Halmstad, Sweden. Two weeks before the start of treatment a grommet was placed in the tympanic membrane. A significant improvement concerning frequency and intensity of vertigo, dizziness, aural pressure and tinnitus was reported by the active group on the visual analogue scales (VAS) questionnaire. In the placebo group no change was the most common finding, followed by worsening of the symptoms and a few improvements. The function in professional and family life improved during active treatment and did not during placebo treatment. Pure-tone audiometry did not improve after placebo treatment, but improved at the frequencies 500 Hz and 1,000 Hz after active treatment. The study showed an improvement in the inner ear symptoms after Meniett treatment. The mechanism may be explained by the influence on the round window membrane pressure receptors or an endolymphatic flow out through the pressure release points, such as the endolymphatic duct and sac, thus activating the longitudinal flow. Other mechanisms are also possible.

Adult↗