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At least 127 records · Page 7Linked to original sources
PubMed1990

[Effects of body posture on cochlear performance].

Experimental research has demonstrated that changes in body position influence auditory function and, specifically, supine position produces a sensorineural hearing loss at low frequencies. The hypotheses to interpret these phenomena are principally referred to an increase of hydrostatic pressure of labyrinthine fluids. In order to evaluate the effects of head position on the cochlear performance a modern test battery has been performed to study cochlear function in 11 normal subjects ranged in age from 22 to 34 years. The tests (Remote Masking:RM; Brief Tone Audiometry:BTA; Critical Ratio:RC) have been evaluated in two positions: sitting upright and supine with the head at a 20 backward angle. The results of our research have shown that in all the cases, the supine position produces a significant shift of the auditory threshold at 250 and 500 Hz, and a decrease of RM values in about all of the cases. We have estimated non statistically significant differences for the RC and BTA values, in more than half of the ears tested. On the basis of the significance given to RM, BTA, RC: we can deduce that the modifications of the auditory performance related to an increase in perilymphatic hydrostatic pressure, induced by the head position are produced by an increase in rigidity of the mechanical vibratory structures of the cochlea rather than the expression of sensorineural damage.

Adult↗
PubMed1989

[Clinical aspects of sudden deafness and vestibulopathy].

Clinical aspects of sudden deafness and sudden vestibular loss. The cases of sudden deafness and/or sudden vestibular loss are 90% idiopathic. Initially they can be overlooked but they can be responsible for an important sensorial impairment. In 65% of cases, and within the first two weeks, there may be a relevant or complete recovery or functional compensation. Etiology and pathogenesis are considered to be pluri-factorial; multiple virus infection including the Herpesvirus family, is the most relevant and better documented cause. Such an infection is responsible for a derangement of inner ear microcirculation, ions imbalance at labyrinthine fluids level, reduction of receptors and nervous supply function. Therapy is essentially symptomatic and therefore the most widely used drugs are cortisonics and heparin. In the Author's opinion also dextran 40, by slow endovenous drip, and carbogen (O2 95% + CO2 5%), by inhalations, are very effective with only rare contraindications. The occurrence of an important number of spontaneous improvements or even recoveries does not authorize therapeutic abstension especially in severe or delayed cases.

Hearing Loss, Sudden↗
PubMedDate not supplied

Cochlear and otoconial abnormalities in capsular otosclerosis with hydrops.

Temporal bones from four patients with capsular otosclerosis were examined by microdissection. Otoconia and abnormal crystalline deposits were studied by scanning electron microscopy and x-ray analytical methods. One patient showed more or less symmetrical invasion of the basilar membrane and osseous lamina by connective tissue from thickened endosteum adjacent to the larger anterior foci. In one ear sensorineural degeneration was circumscribed; in the other it was extensive and associated with cochleosaccular hydrops. Two other patients were deaf, with severe sensorineural degeneration; one had multiple active foci and evidence of cochleosaccular hydrops. In the fourth patient, who had small anterior foci, no specific inner ear pathology was found related to otosclerosis. In the hydropic labyrinths, apatite was present as abnormal deposits in the cochlear duct and as rigid crusts replacing the otoconia. Apparently these changes had been associated with abnormal labyrinthine fluid dynamics rather than with the otospongiotic process per se.

Aged↗
PubMed1993

Betahistine-induced vascular effects in the rat cochlea.

Betahistine (BH) has been used widely to treat cochlear disorders, such as tinnitus and Meniere's disease. The mechanism of action of BH in the cochlea is assumed to be based on its histamine-like effect on H1 receptors in the cochlear vasculature, leading to an increased cochlear blood flow (CBF). Recently it has been shown that BH can strongly affect H3 heteroreceptors (a novel histamine receptor subclass) in the periphery, via an autonomic ligand. This mechanism may also contribute to the BH effects on CBF. This study was to validate BH effects in the cochlear vasculature and to investigate the possible mechanisms of action of this drug in the inner ear vasculature. We assessed the effects of BH on CBF with the laser Doppler flowmeter in 23 rats and concluded that BH affects vascular conductivity in the cochlea in a dose-dependent fashion; betahistine diffuses through the round window, but does not have access to vascular receptors or ligands once in the labyrinthine fluids; and the H1 receptors mediate the systemic and peripheral vascular effects of BH, whereas the cochlear effect involves cholinergic receptors.

Animals↗
PubMedDate not supplied

Pathology of the membranous labyrinth: comparison of T1- and T2-weighted and gadolinium-enhanced spin-echo and 3DFT-CISS imaging.

PURPOSE: To assess the value of unenhanced T1-weighted images, T2-weighted images, gadolinium-enhanced T1-weighted images, and three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) images in depicting lesions of the membranous labyrinth. METHODS: Six patients were studied using 1-T MR; both enhanced (gadolinium-tetraazacyclododecane tetraacetic acid) and unenhanced images were obtained and different sequences compared to determine which provided the most information. RESULTS: A combination of gadolinium-enhanced T1-weighted and 3DFT-CISS images could depict all membranous labyrinth pathology. Unenhanced T1-weighted images were necessary to exclude spontaneous hyperintensity in the membranous labyrinth. Gadolinium-enhanced T1-weighted images were needed to detect enhancing pathology such as labyrinthitis and tumors inside the membranous labyrinth. In these cases, 3DFT-CISS images allowed immediate differentiation between inflammation and tumor. In temporal bone tumors involving the bony and membranous labyrinth, unenhanced and enhanced T1-weighted images often sufficed to suggest the correct diagnosis. Only 3DFT-CISS images were able to demonstrate small structures (as fistulas) and to help us confirm or rule out obliteration of the labyrinthine fluid spaces. 3DFT-CISS images were necessary to detect small congenital malformations of the membranous labyrinth when only MR was performed. Uncalcified obliteration of the labyrinth fluid spaces could be reliably detected only on 3DFT-CISS images. Here also gadolinium-enhanced T1-weighted images had to be obtained because enhancement of the soft tissues inside the membranous labyrinth had been observed. CONCLUSION: The CISS sequence and enhanced T1-weighted sequence formed the best sequence combination for diagnosis of membranous labyrinth lesions; additional, unenhanced T1-weighted images can help one differentiate labyrinthitis, proteinaceous fluid, subacute hemorrhage, or tumor inside the labyrinth.

Adolescent↗
PubMed1996

[Positional impedance tests with acetazolamide: a clinical test for evaluating endolymphatic hydrops].

The authors report on the possible advantages acetazolamide, in conjunction with Positional Impedenzometry, can provide in the detection of minor labyrinthine hydrops and major labyrinthine fluid tension disorders. This study was carried out using the case/control method. The subjects were selected on the basis of symptoms and clinical examination revealing signs of endolymphatic hydrops. Tonal audiometry and positional impedenzometry according to Marullo were performed both before (pre-test) and after i.v. administration of 500 mg sodium acetazolamide (post-ACZ1 and post-ACZ2). Audiometry showed that in 77.2% of the cases there was a significant variation in threshold. In positional impedenzometry the average post-ACZ1 (delta PISC went from 22.06% (pre-test) to 13.16% and the post-ACZ2 (delta PISC went to 23.15%). On the other hand no significant changes were seen in the controls. Some hypotheses are offered on the mechanisms giving rise to these effects and particular attention is focused on the effect acetazolamide has on the carbon dioxide in the endolymphatic sac. In conclusion the authors consider the advantages this method offers over the "classical" tests used in diagnosing Ménière's Disease and minor hydrops.

Acetazolamide↗
PubMed1996

[Wegener granulomatosis: a clinical case with parossistic positional vertigo due to involvement of the lateral semicircular canal].

The ear is involved in more than 20% of all cases of Wegener Granulomatosis (W.G.): such involvement takes place either through direct proliferation of the necrotic-granulomatosis tissue in the middle ear, or is a consequence of perieustachian tube infiltration from the rhinopharnyx. The inner ear is affected later and it is not clear as to exactly how. The present paper deals with the case of a 63-year-old woman who had a year been suffering from bilateral ear pain, and persistent otorrhea with typical signs of purulent chronic middle-ear otitis. During the course of the illness the patient complained of atypical paroxymal positional vertigo, compatible with cupulolithiasis of the semi-circular horizontal canal (as per E.N.G. recording). Transoral biopsy of the rhinopharynx and of the left nasal fossa revealed histopathological signs compatible with W.G.. In the light of post-mortem temporal bone studies performed by Friemann and Blatt on W.G. patients the present case could lead to further studies regarding the advancement of this pathological process within the middle and inner ears and the etiopathogenetic mechanisms involved. In particular, during the course of W.G., the appearance of benign paroxymal positional vertigo through cupulolithiasis of the semicircular horizontal canal may be justified: a) by the progressive involvement of the posterior labyrinth structures affecting the semicircular canals prior to the lateral canal and running on to the posterior canal; b) by the discovery of proteiform material in the labyrinthine fluids.

Cerebrospinal Fluid Otorrhea↗