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Results for “Cochlear Aqueduct”

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At least 235 records · Page 13Linked to original sources

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↗

PubMed2002

Pineal region tumor manifesting initially as hearing impairment.

An 18-year-old male presented with a pineal region germinoma with hearing impairment as the chief complaint. Magnetic resonance image demonstrated a well-enhanced multi-cystic tumor extending into the upper fourth ventricle and wall of the bilateral lateral ventricles. Audiometry revealed bilateral mild hearing impairment in the low frequencies. Auditory brainstem response recording showed low amplitudes in all waves (IV-V/I ratio < 1) with prolong latencies (I-V and III-V) on the right but no discernable wave at 60 dB clicks on left. Hearing impairment and audiometric findings were improved after ventriculoperitoneal shunt operation. The hearing impairment appeared to be a mixed (conductive and sensorineural) type. The tumor was responsible for the sensorineural deafness because of invasion and compression of the central auditory structures. The inferior brachium was maximally compressed anterolaterally by the dilated bilateral lateral ventricles and posteromedially by the tumor. Hydrocephalus caused conductive deafness by halting or arresting the footplate of stapes movement, as a consequence of high-pressure transmission through the cochlear aqueduct.

Adolescent↗

PubMedDate not supplied

The effect of intracisternally injected ouabain on perilymph electrolyte concentrations.

A means for altering the ionic composition of perilymph utilizing the cochlear aqueduct and cerebrospinal fluid in chinchillas is introduced. A decrease in sodium and an increase in potassium concentration in perilymph was observed after ouabain was injected into cerebrospinal fluid. The time course of changes in the perilymph paralleled the CSF change but with a time lag which had not reached equilibrium within 60 minutes.

Animals↗

PubMed1982

Cerebrospinal fluid and acoustic neurinoma specific proteins in perilymph.

White rabbits were immunized with pooled and concentrated cerebro-spinal fluid (CSF) and with tumour homogenate concentrate from specimens taken from five patients with acoustic neurinoma. The absorbed anti-CSF-antitumour antiserum was tested with the micro-immunodiffusion test against normal human serum (NHS), CSF, perilymph and CSF from tumour patients and tumour homogenate. NHS showed no precipitates in any of the tests. One protein band was observed in all the other four reactants. Tumour tissue and perilymph had two proteins in common. Diffusion from the CSF space into the perilymph can thus occur via both the cochlear aqueduct and the internal acoustic meatus.

Cerebrospinal Fluid Proteins↗

PubMed1988

Audiological aspects of idiopathic perilymphatic fistula.

Audiological findings in 40 patients with surgically confirmed idiopathic perilymphatic fistula were investigated. Most patients complained of roaring tinnitus, hearing impairment, ear fullness, and hyperacusis. However, a popping sound and a streaming water-like sound were noticed only in 8. Pure-tone sensitivity included every kind of hearing impairment, from sudden profound, to normal sensitivity. Development of hearing impairment was sudden, and deteriorated further, fluctuating in order of frequency. In the early stage of perilymphatic fistula patients had low-frequency hearing impairment and evidenced dominant-negative SP in the electrocochleogram. These findings suggest that a fistula of the inner ear window is not solely responsible for the wide variety of signs and symptoms, and that there must be simultaneous lesions in the membranous labyrinth.

Adolescent↗

PubMed1991

Hearing decrease after loss of cerebrospinal fluid. A new hydrops model?

In a prospective study of 12 patients undergoing operation for acoustic neuromas the hearing on the contralateral ear was tested before and systematically day by day after operation. In 11 cases a perceptive loss of at least 20 dB was found at one or more frequencies during the first 2 postoperative weeks. A maximal average threshold decrease of 16.5 dB was found in the treble (2.4, 8 kHz average), while a tendency of a more pronounced decrease of 19.6 dB was seen in the low frequencies (125, 250, 500 Hz average). After 3 months the hearing had normalized in all cases. The explanation for the transitional loss supports the present theory: The loss of cerebro-spinal fluid during operation diminishes the CSF pressure. This decrease is transmitted to the perilymph via the cochlear aqueduct producing a transitory perilymphatic hypotonia, which in turn hydromechanically results in a relative endolymphatic hypertension mimicking an endolymphatic hydrops thus representing a human hydrops model.

Adult↗

PubMed1994

Effect of craniotomy and cerebrospinal fluid loss on the inner ear. An experimental study.

Craniotomy with cerebrospinal fluid (CSF) suction was performed on 18 guinea pigs to determine the effects on the inner ear morphology. Six control animals received anaesthesia only and 12 were operated on with a postoperative survival time of 1 or 24 h. The histologic examinations showed no signs of endolymphatic hydrops or injury to other structures in any of the animals. In 11 of the operated animals, red blood corpuscles were demonstrated in the perilymphatic space of the cochlea, the subarachnoid space, and the cochlear aqueduct (CA). After 1 h survival time blood had entered primarily the basal part of the scala tympani, but in the animals of 24 h survival time the blood was more abundant in both the scala tympani and the scala vestibuli indicating flow within the inner ear. The CA thus provides a pathway between the CSF and the whole of the perilymph through which noxious effects could take place.

Animals↗

PubMedDate not supplied

Impedance measurement as a noninvasive technique for the monitoring of intracranial pressure variations.

In previous reports it has been demonstrated that jugular compression causes a modification of middle ear acoustic impedance; this phenomenon has been named the jugulotympanic reflex (JTR). The aim of the present study was to contribute to the understanding of the origin of this reflex. We have analyzed the middle-ear impedance modifications induced by unilateral and bilateral jugular compression in 12 normal subjects, in 12 patients afflicted with otosclerosis, in 3 patients with Menière's disease and in 6 patients demonstrating intracranial hypertension. In the latter group, the cerebrospinal fluid (CSF) pressure was simultaneously recorded. The JTR was elicited in each normal subject and in each patient affected by Menière's disease and intracranial hypertension, while it was usually absent or modified in otosclerotic patients. The absence of the JTR in otosclerotic patients and, above all, the correspondence between CSF pressure and the middle-ear impedance modification induced by jugular compression suggest that it is due to the transmission of pressure changes from the CSF to the perilymph through the cochlear aqueduct.

Acoustic Impedance Tests↗

PubMed1993

The prevalence of perilymphatic hypertension in subjects with tinnitus: a pilot study.

This study investigated the prevalence of perilymphatic hypertension (raised perilymphatic pressure) in a population of subjects with tinnitus. A review of the literature showed how changes in perilymphatic pressure could affect tympanic membrane displacement measurements. This review also revealed that perilymphatic hypertension was more likely to occur in young females (less than 45 years) than in other subjects. An experiment was designed to test 32 subjects, who were divided into four groups according to their age and sex. These subjects underwent several routine audiological tests and were then tested with the tympanic membrane measurement system to determine the perilymphatic pressure of both ears. Statistical analysis of the experimental results showed that the young females had raised perilymphatic pressure. This was significantly higher than the perilymphatic pressure of the other test groups and of that of a normal population. The young females also exhibited other symptoms indicative of raised perilymphatic pressure. The raised pressure was thought to be due to an increase in fluid pressure which is more likely to occur in females due to variations in the levels of circulating hormones with menstrual irregularities, pregnancy and the menopause.

Adult↗

PubMed1998

Bilateral otoacoustic emissions pass in a baby with Mondini deformity and subsequently confirmed profound bilateral hearing loss.

Evoked otoacoustic emissions are well established as a hearing screening technique and are used extensively in paediatric audiology. They are believed to originate from the outer hair cells and can be detected in almost 100% of normally hearing ears; even a mild hearing loss has been shown to abolish otoacoustic emissions. Results are presented of a baby boy born at 29 weeks' gestation requiring 77 days of neonatal care, but experiencing no complications following discharge from the neonatal unit. This child had clear bilateral evoked otoacoustic emissions at almost four months of age, but was subsequently found to have a profound bilateral hearing impairment and absent otoacoustic emissions. Radiological investigations revealed bilateral Mondini dysplasia, and this child has now been implanted with a multi-channel MXM Digisonic cochlear implant. He is progressing well and shows awareness of sound. Approximately 10 previous cases of otoacoustic emissions occurring in profoundly deaf ears have been reported in the literature. Although it is likely that this child's hearing loss was progressive in nature, the authors believe that this is the first reported case of otoacoustic emissions being recorded in the presence of Mondini dysplasia. This raises concerns about the use of neonatal screening in isolation without adequate mechanisms for later identification of hearing impairment, although it is acknowledged that it represents a rare situation.

Child, Preschool↗

PubMed2006

Ventriculoperitoneal shunt insertion for the treatment of refractory perilymphatic fistula.

OBJECT: The goal of this study was to provide preliminary data regarding clinical and functional outcome, including postoperative morbidity, related to ventriculoperitoneal (VP) shunt insertion for refractory perilymphatic fistula. METHODS: The authors retrospectively reviewed the records of seven consecutive patients who had undergone VP shunt insertion for medically and surgically refractory perilymphatic fistula between 1996 and 2004. Patients were also contacted by telephone and asked to assess retrospectively their symptomatic improvement, changes in functional status, and changes in work status following shunt placement. Preoperative and postoperative functional statuses were assessed using a standardized instrument. In each patient, preoperative opening pressure was measured via lumbar puncture. Pressures ranged from 160 to 300 mm H2O, with a mean of 241 mm H2O. All patients reported significant improvement in symptom severity following surgery. Two patients reported complete resolution of symptoms. Three patients were able to resume full-time work. Clinically significant improvement in functional status was noted in six of seven patients. All patients would recommend the procedure to others in a similar situation. CONCLUSIONS: Data in this study suggest that some patients with disabling vertigo, tinnitus, and headache due to perilymphatic fistula, whose conventional medical and surgical therapies have failed to produce a cure, benefit from VP shunt insertion. The authors hypothesize that VP shunt placement blunts intracranial pressure increases, which would cause secondary elevations in perilymphatic fluid pressure. Shunt insertion reduces perilymph leakage into the middle ear and may permit closure of the fistula.

Aged↗

PubMed2003

Unilateral hearing loss in children with shunt-treated hydrocephalus.

This study investigated the characteristics of hearing loss in children with ventriculoperitoneal (VP) shunted hydrocephalus. Twelve hydrocephalic children with patent VP shunts participated. The etiology of the hydrocephalus was either intraventricular hemorrhage or spina bifida. Audiometric examination included pure-tone air conduction thresholds, tympanometry, contralateral and ipsilateral acoustic reflex thresholds (ARTs), and distortion product otoacoustic emissions (DPOAEs). A unilateral, high-frequency, cochlear hearing loss was found in the ear ipsilateral to the shunt placement in 10 (83%) of the 12 shunt-treated hydrocephalic children. No hearing loss was observed in the ear contralateral to shunt placement. Based on the pure-tone audiometric findings, coupled with the decrease in DPOAE amplitude in the shunt ear, the hearing loss appears to be cochlear in nature. We suggest that cochlear hydrodynamics are disrupted as the result of reduced perilymph pressure, a consequence of cerebrospinal fluid (CSF) reduction due to the combined effects of a patent shunt and a patent cochlear aqueduct. In addition, a concomitant brain stem involvement is evidenced in the ART pattern, possibly produced by the patent shunt draining the CSF from the subdural space, resulting in cranial base hypoplasia.

Acoustic Impedance Tests↗

PubMed2004

Management of the draining ear in children.

There are a variety of causes of otorrhea in children. The most important factor in reaching the proper diagnosis and providing relief of the problem is aural toilet. Once adequate debridement has been performed, the diagnosis is usually clearer, and treatment with ototopicals is significantly more effective. Most cases of otorrhea are due to infection or granulation tissue and can be managed initially with appropriately selected ototopical medication, thereby avoiding the risks and side effects of systemic therapy and the need for referral to a specialist. However, otorrhea in children that is refractory to medical therapy may be due to retained tympanostomy tubes or insidious pathology such as cholesteatoma or malignancy. In such cases, prompt referral to the otolaryngologist can facilitate accurate diagnosis and successful management.

Anti-Bacterial Agents↗

PubMed1990

[Transmission of changes in the external ear atmospheric pressure to the perilymph].

Using guinea pig, pressures in the external ear canal, in the middle ear and in the perilymph were registered simultaneously, while pressure was applied to the external ear canal using an impedance audiometer. In the first experiment, applied pressure was changed in the range from 200 mmH2O to -200 mmH2O with and without the opening of the otic bulla. The change in the perilymphatic pressure with the opening was smaller than that without the opening. The result indicates that the external ear pressure is transmitted to the perilymph not only via the ossicular chain but also via the middle ear cavity without the opening, while it is exclusively transmitted via the ossicular chain with the opening. Pressure transmission to the perilymph was significantly impaired either by disrupting the ossicular chain or by closing the round window niche, especially by the latter. Thus the middle ear cavity itself plays an important role in pressure transmission from the external ear canal to the perilymph mainly via the round window. In the second experiment, applied pressure to the external ear canal was changed in the range from 1000 mmH2O to -1000 mmH2O after the Eustachian tube being closed. Between 400 mmH2O and -200 mmH2O, the middle ear and perilymphatic pressures paralleled well with the applied pressure. Beyond these levels, the middle ear pressure increased or decreased in response to the applied pressure but the perilymphatic pressure reversed against the middle ear pressure. Communication between perilymph and cerebrospinal fluid via the cochlear aqueduct is thought to be a major factor causing this reversal which, in turn, aggravates pressure gradient between the middle ear and the perilymph.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

High-resolution MR images of inner ear internal anatomy using a local gradient coil at 1.5 Tesla: correlation with histological specimen.

PURPOSE: To obtain high-resolution MR images of the inner ear at 1.5 Tesla with a local gradient coil and to correlate these images with the histological specimen. MATERIALS AND METHODS: All studies were performed on a 1.5 Tesla MR unit with a local gradient coil (23 mT/m, slew rate of 107 mT/m/ms). The cranio-facial region of a cadaver was examined using 3D-fast spin echo (FSE) imaging with the voxel size of 0.27 mm x 0.27 mm x 0.5 mm in 9 h 37 min. Two normal volunteers were examined with the same system using 3D-FSE imaging with the voxel size of 0.20 mm x 0.26 mm x 1.0 mm in 57 min. These images were correlated with the cadaver images and histological specimens. RESULTS: On cadaver images, internal structures such as the macula utriculi, macula sacculi, crista ampullaris, lamina spiralis ossea, ligamentum spirale cochleae, modiolus, scala tympani, scala vestibuli, and cochlear aqueduct were visualized. On the images of both volunteers, the same structures were visualized as on the cadaver images. CONCLUSIONS: This study confirmed that high-resolution MR images obtained at 1.5 Tesla can visualize inner ear internal anatomy. Knowledge obtained in this study may be of significant value for the diagnosis of pathology in the area of the inner ear.

Aged↗

PubMed1999

Stress electrocochleography.

Electrocochleographic recordings after changes of middle-ear and intracranial pressure were studied in a group of otologically normal subjects and in patients with suspected Ménière's disease. Electrocochleography performed under these conditions was called stress electrocochleography. It was useful to distinguish among Ménière's disease, benign positional vertigo, and a round-window fistula. Changes of middle-ear pressure, whether positive or negative, always resulted in a rise of the SP/AP ratio. Raised intracranial pressure after Trendelenburg positioning showed fluctuations of the SP/AP ratio in both normal subjects and symptomatic patients. However, in normal subjects, a congruent pattern of these fluctuations was apparent, whereas symptomatic patients exhibited a discordant pattern. The discordant pattern, typical for Ménière's disease, showed an increase of the SP voltage, whereas the AP voltage decreased. In benign positional vertigo, the SP voltage decreased, and the AP voltage increased, once during Trendelenburg positioning and again at the end of the test when starting position was resumed. During raised intracranial pressure after the Queckenstedt maneuver, round-window fistulas showed an increase of the SP voltage, whereas the AP voltage decreased considerably. At our clinic, stress electrocochleography has become an important neurootological test in the differential diagnosis of Ménière's disease.

Action Potentials↗

PubMed2000

[Assessment of perilymphatic pressure using the MMS-10 tympanic membrane displacement analyzer (Marchbanks' test) in patients with Meniere's disease: preliminary report].

OBJECTIVES: The aim of this study was to investigate non-invasive measurement of perilymphatic pressure using the MMS-10 tympanic displacement analyzer (Marchbanks' test) in patients with Meniere's disease. METHODS: We performed measurements in 20 patients with Meniere's disease and in 9 normal subjects with normal hearing. Data were collected in three groups: healthy ears of normal-hearing patients, healthy and affected ears in patients with Meniere's disease. RESULTS: We found no significant differences between the 3 groups for the types of the graph. Measurements of the tympanic membrane displacement test variables (Vi and Vm) showed large inter-subject variations. No significant difference was found between the 3 groups for cochlear aqueduct patency. CONCLUSION: Preliminary results of this short series show that assessment of perilymphatic pressure using the MMS-10 procedure does not seem to be useful in Meniere's disease.

Adolescent↗

PubMed1998

[Sudden sensorineural hearing loss and jugular bulb diverticulum].

The relationship between high placed jugular bulb (diverticulum) and inner ear disorder is not well known. Three of 19 patients with sudden sensorineural hearing loss (SSHL) treated in 1995 had right side jugular bulb diverticulum revealed by CT scan and MRA. One of the 3 SSHL cases complicated with delayed endolymphatic hydrops. The exact mechanism of causation of inner ear symptom is not clear, but may partly be due to pressure effects with the jugular fossa encroaching on inner ear structure such as the cochlear aqueduct and vestibular aqueduct, and due to turbular flow in the diverticulum striking the inner ear. It is needed to further study the influence of the diverticulum on the inner ear.

Adult↗