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PubMed1995

[Noninvasive assessment of intracochlear pressure. III. Case reports of patients with intracochlear hyper- and hypotension].

It was the scope of two previous papers to outline the basics and possible neurotological applications of the tympanic membrane displacement technique (TMD). The present paper is aimed at briefly reviewing five distinct cases where a sudden sensorineural hearing loss with/without tinnitus could be monitored by the TMD technique. These features include a sudden hearing loss upon lumbar puncture, the audiological manifestation of an internal hydrocephalus, stapes gusher and the round window rupture. All symptoms are based on a change in intracranial and intracochlear pressure which in turn leads to the manifestation of the previously unknown sensorineural hearing loss and/or tinnitus.

Adult↗
PubMed1991

[Diffusion of amikacin at the membrane of the round window. Histologic and electrophysiologic study in newborn guinea pigs].

The aim of our study was to evaluate the permeability of the round window membrane for amikacin during postnatal development. The morphologic and electrophysiologic changes in the cochlea were dependent on the applied concentration of amikacin. When giving high doses a complete degeneration of hair cells and deafness could be found. In these cases an influence on the contralateral cochlea could be proved.

Amikacin↗
PubMed2000

Round window gentamicin mu-catheter--a new therapeutic tool in Ménière's disease.

The vestibulotoxic effect of gentamicin is well documented; however, there is no general agreement on the gentamicin dose needed to control vertigo attacks without affecting the hearing. In the current study, 14 patients with Ménière's disease refractory to medical treatment were treated by small doses of gentamicin delivered via a mu-catheter, placed into the round window niche. An electronic micropump delivered 10 microliters (100 micrograms)/h. The patients received a total dose of 4-14 mg. The effects on the vestibular symptoms were most encouraging, with cessation of vertigo in 13 of the 14 patients, control of Tumarkin attacks in 4 out of 6 cases and release of aural pressure and fullness in 2 out of 4 cases. According to the recommendations of the Committee on Hearing and Equilibrium, the patients in this material belonged to functional levels 5 and 6. At the last clinical follow-up, five patients were classified as level 1, eight patients as level 2 and one patient as level 3. A significant hearing loss was seen in one patient; however, this was most likely due to the natural development of the disease in this particular case. The results look promising, but must be investigated further in a placebo-controlled study.

Adult↗
PubMed2000

Topical aminoglycoside ototoxicity: attempting to protect the cochlea.

Cochlear damage following topical application of aminoglycoside antibiotics to the round window membrane is a recognized phenomenon in both animal experiments and clinical reports. The authors have recently reported the ability of the free radical scavenging agent, alpha lipoic acid, to protect against the cochleo-toxic side effects of systemically administered aminoglycoside antibiotics. This study attempts to determine if the protective effect of this free radical scavenging agent is also seen following topical aminoglycoside application. Animals were implanted with osmotic pumps which delivered 2.5 microl/h solution of either neomycin 5% or neomycin plus alpha lipoic acid (50 mg/ml). Control animals received normal saline solution. Drug solutions were presented directly to the round window membrane over a 7-day period. Auditory sensitivity was monitored using compound action potentials (CAPs) of the auditory nerve recorded through an implanted chronic electrode terminating at the round window. Sixteen animals were entered into the study and randomized to one of the above groups. All animals receiving neomycin solution, with or without alpha lipoic acid, maintained normal thresholds for the first 3 days of the treatment period. Animals receiving neomycin solution alone experienced profound and rapid deterioration in auditory sensitivity, which was maximal by day 6. Animals receiving neomycin plus alpha lipoic acid also experienced significant cochlear damage; however, the rate of deterioration was slower than that seen in the group receiving neomycin alone. All control animals receiving saline maintained good hearing thresholds throughout the treatment period.

Administration, Topical↗
PubMed2003

Acute treatment of noise trauma with local caroverine application in the guinea pig.

Intense sound stimulation may result in excessive glutamate release from the inner hair cells, resulting in binding to the postsynaptic glutamate receptors and leading to neuronal degeneration and functional impairment. In this study we investigated the therapeutic effect and time window of caroverine, an N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist, on noise-induced hearing loss Guinea pigs were exposed to one-third octave band noise centered at 6.3 kHz (110 dB sound pressure limit) for 1 h. One or 24 h after noise exposure, caroverine was applied to the round window membrane. Auditory brainstem responses were recorded at regular time intervals. It was shown that caroverine could significantly decrease hearing impairment after noise trauma when applied 1 but not 24 h after noise exposure.

Administration, Topical↗
PubMed2004

Cochlear implantation via the round window membrane minimizes trauma to cochlear structures: a histologically controlled insertion study.

OBJECTIVE: To evaluate cochlear implant trauma to intracochlear structures when inserting the electrode via the round window membrane. MATERIAL AND METHODS: Eight fresh human temporal bones were evaluated histologically after insertion using two types of cochlear implant array. Bones underwent a special fixation and embedding procedure that allowed sectioning of undecalcified bone with the electrode in situ. Insertions depths were evaluated radiologically and histologically. RESULTS: All arrays were found in the scala tympani of the cochlea. Basal trauma could be avoided in all but one specimen. The mean depth of insertion was 382.5 degrees. Apically, only one implanted bone showed cochlear trauma exceeding lifting of the basilar membrane. CONCLUSION: Insertions through the round window membrane were shown to be atraumatic, even in basal cochlear regions. This route of insertion might be very effective for combined electric and acoustic stimulation of the auditory system.

Cochlea↗
PubMed2005

Cochleostomy site: implications for electrode placement and hearing preservation.

CONCLUSIONS: With recent increased interest in minimizing intracochlear trauma and preserving residual hearing during cochlear implantation, increased attention must be paid to the cochleostomy site. The results of this paper demonstrate that the cochleostomy must be made inferior, rather than anterior, to the round window to ensure scala tympani insertion and to decrease the likelihood of insertion-induced intracochlear damage during electrode insertion. OBJECTIVE: To describe the complex anatomy of the hook region of the cochlea, specifically in relation to the optimal placement of the cochleostomy for cochlear implant electrode insertion to potentially achieve hearing preservation. The authors believe that previous industry recommendations and described surgical techniques have resulted in cochleostomies being placed in anatomical positions that possibly result in electrode insertions that damage the basilar membrane and/or other cochlear structures. MATERIAL AND METHODS: The results of a number of temporal bone studies were reviewed with attention being paid to the anatomical relationship of the basilar membrane and spiral ligament to the round window membrane. For different cochleostomy sites the potential for damage to intracochlear structures, particularly the basilar membrane and organ of Corti, was assessed. RESULTS: The review of electrode insertion studies into human temporal bones, as well as a post-mortem anatomical study of implanted temporal bones, showed an increased risk of scala vestibuli insertions and insertion-induced damage to intracochlear structures when the cochleostomy was performed more anterior to the round window. These results were endorsed by studies detailing the anatomy of the hook region of the cochlea.

Basilar Membrane↗
PubMed2004

Nitric oxide induces apoptosis of the hair cells of cochlea.

OBJECTIVE: Nitric oxide (NO) has a toxic effect on neuronal cells related to glutamate receptors. NO released from post-synaptic cells with glutamate receptors can induce nearby cell death. In this experiment, we examined the effect of NO on cochlear hair cells. METHODS: Two concentrations, 0.5 and 0.1 molar concentration (MC) of 1-hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5), which is a NO donor, were placed on the round window of the guinea pig cochlea and its morphological changes were investigated at 12, 28, 72 h after the treatment. RESULTS: By the trypan blue dye extrusion method, the cell death was recognized in the outer hair cells at the percentage 0, 36.0+/-6.6, 4.9+/-1.2% at 12, 28, 72 h after treatment respectively in the group 0.5 MC NOC-5, but no inner hair cell death was recognized. In the group of 0.1 MC NOC-5 and control any cell death was not detected. Transmission electron microscopy revealed this cell death was characteristic of apoptosis. CONCLUSION: The findings that apoptosis was induced in the outer hair cells of the organ of Corti by NO suggests the possibility that the cochlea is affected when extra NO release occurs there, leading to cochlear dysfunction.

Animals↗
PubMed1992

A comparison of round-window and transtympanic promontory electric stimulation in cochlear implant candidates.

We compared within-subjects electrical thresholds and dynamic ranges obtained with direct round-window and transtympanic promontory stimulation carried out preoperatively in 12 patients who were candidates for a cochlear implant. Square waves with frequencies of 50, 100, 200, and 400 Hz were delivered in a 50% duty cycle to both sites in each patient. With the exception of threshold at 50 Hz (promontory thresholds were lower than round-window thresholds), there were no statistically significant differences for either thresholds or dynamic ranges between the two sites of stimulation. There was a general trend for round-window thresholds to be lower and dynamic ranges larger, especially for the higher frequencies of stimulation. Mean threshold slopes for the two sites of stimulation were nearly identical.

Adult↗
PubMed1996

Blockade of opioid-induced changes in auditory function at the level of the cochlea.

OBJECTIVE: We have previously investigated the auditory neural effects of the kappa-opioid receptor agonist, (-)pentazocine. When administered intravenously (i.v.), this drug temporarily alters auditory nerve compound action potential (CAP) amplitudes. To test the hypothesis that the observed neural effects of i.v. (-)pentazocine occur via kappa-receptor interactions within the cochlea, we attempted to block these effects by employing a specific kappa-opioid receptor antagonist applied directly to the cochlear round window (RW) membrane. DESIGN: In 31 normal-hearing, male pigmented chinchillas, amplitude changes in the click-evoked auditory CAP (N1) were tracked at six stimulus intensities during a baseline and a postbaseline period in which i.v. (-)pentazocine (8 mg/kg) was administered. (-)Pentazocine administration was preceded by the delivery to the cochlear RW membrane of an artificial perilymph solution given alone or containing the kappa-opioid receptor selective antagonist, norbinaltorphimine (Nor-BNI), which was administered at two concentrations in separate groups of animals. RESULTS: The amplitude increase in the CAP after (-)pentazocine was significantly reduced when i.v. (-)pentazocine was preceded by RW-administered Nor-BNI (4 mM). CONCLUSIONS: The reversibility of agonist effects by Nor-BNI indicates direct or indirect opioid kappa-receptor-mediated auditory neural effects at the level of the cochlea and suggests a connection between kappa-receptors and auditory neural function.

Animals↗
PubMed2001

Use of the round window microcatheter in the treatment of Meniere's disease.

OBJECTIVES/HYPOTHESIS: Transtympanic gentamicin is an increasingly popular treatment for Meniere's disease. The present report examines the 2-year follow-up of our first 27 patients with Meniere's disease treated with the use of microdose gentamicin through the Round Window Microcatheter. We applied the 1995 American Academy of Otolaryngology-Head and Neck Surgery criteria to this patient group to analyze the results of treatment. STUDY DESIGN: This study is an evaluation of consecutive patients with predetermined data collection on each patient. METHODS: Patients with confirmed Meniere's disease underwent placement of the Round Window Microcatheter, which was filled with 10 mg/mL gentamicin, after placement into the round window niche was confirmed. Ten milligrams per milliliter of gentamicin was injected into the catheter by hand on two occasions after device placement in the first several patients. The remaining patients had continuous infusion of 10 mg/mL gentamicin at 1microL/h for the next 10 days. The catheter was removed 10 days after placement. All patients underwent an extensive set of hearing and vestibular tests on several occasions before, during, and after treatment. RESULTS: In the patients in the study, vertigo was eliminated in 92.6%, with 3.7% of patients (1/27) demonstrating a mild permanent threshold shift in hearing. Tinnitus and pressure were significantly reduced in more than 65% of patients. Only one patient demonstrated a reduction of vestibular function after treatment. CONCLUSIONS: Results of this study on this group of patients indicate that vertigo can be controlled in the long term using microdose gentamicin without a significant reduction in cochlear or vestibular function in most of the patients in our series. Our results are compared with the published literature examining transtympanic injection. In addition, the underlying science supporting this type of treatment is examined.

Adult↗
PubMed2004

Infratemporal fossa approach to the hypoglossal canal: practical landmarks for elusive anatomy.

OBJECTIVE: At the conclusion of the article the readers should be able to safely and reliably find the hypoglossal canal using the infratemporal fossa approach. HYPOTHESIS: Very little has been written on the regional anatomy of the hypoglossal canal as seen through a transtemporal approach. This project attempts to further define the anatomy of the hypoglossal canal and provide the surgeon with guidelines for reaching it. Our hypothesis is that the hypoglossal canal can be safely and consistently reached by way of the temporal bone with preservation of hearing and cranial nerves (CN) IX to XI. STUDY DESIGN: Prospective anatomic study. METHODS: The study was performed using cadaver temporal bones. Infratemporal fossa Fisch type-A dissections were performed. The hypoglossal canal was then completely exposed. The distance from the canal to the jugular bulb, carotid artery, round window, lateral canal, and roots of CN IX to XI were recorded. RESULTS: Fifteen temporal bones were dissected and measured. The position of the hypoglossal canal is consistently located anterior, inferior, and medial to the jugular bulb. The distance from midcanal to the jugular bulb and the roots of CN IX to XI at the posterior fossa dura was 5.3 mm +/- 0.82 and 7.1 mm +/- 2.49, respectively. The distance from the carotid artery where it meets the jugular vein to the midcanal was 15.3 mm +/- 2.09. The distance from the round window to the canal was 21.7 mm +/- 3.17. CONCLUSIONS: The hypoglossal canal can be consistently reached using the infratemporal fossa approach. Hearing and CN IX to XI can be preserved. The distance from the jugular bulb and roots of CN IX to XI can be used as guideposts. If a tumor is involving the bulb, then the carotid artery and the round window are the next most reliable indicators of position.

Accessory Nerve↗
PubMed2004

Round window application of D-methionine, sodium thiosulfate, brain-derived neurotrophic factor, and fibroblast growth factor-2 in cisplatin-induced ototoxicity.

HYPOTHESIS: In this study we tested the effect of local administration of D-methionine, sodium thiosulfate, brain-derived neurotrophic factor, and fibroblast growth factor-2 on cisplatin ototoxicity in guinea pigs to the round window membrane. BACKGROUND: Cisplatin is an important antineoplastic agent in the therapy of many malignancies. Its clinical utility is limited by severe side effects, including ototoxicity. Recent studies have shown protection against cisplatin ototoxicity in animal experiments by the systemic administration of D-methionine and sodium thiosulfate. Growth factors such as brain-derived neurotrophic factor and fibroblast growth factor-2 also have shown otoprotective effects in in vitro studies. METHODS: Osmotic pumps (Alzet) were implanted unilaterally in 30 guinea pigs. Five groups of six animals received either D-methionine, sodium thiosulfate, fibroblast growth factor-2, brain-derived neurotrophic factor, or saline 0.9%. Cisplatin was administered intraperitoneally for 5 consecutive days. Distortion product otoacoustic emissions were recorded every day. The animals were killed on day 6, and their cochleae were removed and analyzed by transmission electron microscopy. RESULTS: Compared with control animals, guinea pigs treated with D-methionine showed better otoacoustic emissions on days 3 and 4 (Mann-Whitney test, p < 0.05). The differences were not evident on days 5 and 6. Sodium thiosulfate, brain-derived neurotrophic factor, and fibroblast growth factor-2 showed no significant protective effect. CONCLUSION: Local application to the round window membrane can be used as an effective treatment in the prevention of cisplatin toxicity. Local application may avoid systemic side effects and reduce the antineoplastic effects of cisplatin.

Administration, Topical↗
PubMed1980

Round window membrane rupture and acquired sensorineural hearing loss in children.

The aetiology of acquired sensorineural hearing loss includes many conditions. The disparity between the number of children affected by the conditions which are supposed to cause hearing loss and the number of children who are actually deaf, has never been satisfactorily explained. Clinical features observed in children with surgically proven round window membrane rupture have been noted in all conventional aetiological groups. These features include otitis media, doubt about the hearing status in early life, disturbance of balance and other occasional neurological phenomena. Wide variation in the appearance of round window niche has been observed in children with secretory otitis and similar appearances have been observed in children with proven round window membrane rupture. The appearances may represent a reaction to perilymph. Round window membrane rupture is probably common and may prove to be a unifying factor for many cases of acquired sensorineural hearing loss. Occasional neurological phenomena may be related to it.

Adolescent↗
PubMed1990

Electrical stimulation of the round window: a selection procedure for single-channel cochlear implantation.

Many suggestions have been made as to the most appropriate tests for the selection of patients for cochlear implantation. One of the most appropriate tests when selecting patients for a round window extracochlear device is stimulation of the round window itself by a temporary electrode of the same size. Fourteen patients have been tested, 7 of whom were judged to have a good response to electrical stimulation. Six patients have gone on to permanent implantation with a round window cochlear implant.

Acoustic Impedance Tests↗