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At least 739 records · Page 41Linked to original sources
PubMed1977

The ductus reuniens and utriculo-endolymphatic valve in the presence of endolymphatic hydrops in guinea-pigs.

Described in the foregoing are postoperative changes in the ductus reuniens and the utriculo-endolymphatic valve of the membranous labyrinth of the inner ear upon obstruction of the endolymphatic duct in normal guinea-pigs. The ductus reuniens was postoperatively dilated more than three times that of the normal ear, and dilated to a maximum degree within the first 12 hours. The utriculo-endolymphatic valve was found to be open two days after the operation, and there was a tendency for the number of animals with an open valve to increase with time. At three weeks and also at two months after the operation, there were some animals whose utricles were compressed by the dilated saccules, and as a result, their utricular ducts and utriculo-endolymphatic valves appeared narrowed.

Animals↗
PubMed1980

Pathology of endolymphatic hydrops.

The term 'endolymphatic hydrops' is not a definitive diagnosis since the condition occurs in a variety of otological disorders. Endolymphatic hydrops was found in 57 ears (9 per cent) of the 703 temporal bones in the collection of the Ear Research Institute, Los Angeles. These 57 ears included normal ears of two newborns, post-stapedectomy ears, and ears with the primary diagnosis of Menière's disease. Paget's disease, congenital syphilis, and chronic otitis media. The typical clinical picture of fluctuant hearing loss, pressure, tinnitus, and episodic vertigo occurred in about one-third of the cases with histologically documented hydrops. This symptom complex was common in cases with diffuse, bilateral, cochleo-saccular, or progressive hydrops. A reliable clinical test to determine the presence of endolymphatic hydrops is needed. Complete neurotologic evaluation is indicated in every case suspected of having hydrops to determine specific causes.

Adolescent↗
PubMed1988

Traumatic perilymphatic fistulae of the lateral semicircular canal.

Fifteen patients with perilymphatic fistulae were evaluated. Of these patients, three had CSF leaks in addition to the perilymphatic fistulae. Eight patients had fistulae of one or both windows; two had fistulae confined to the lateral semicircular canal; and two had combined fistulae of both round window and lateral semicircular canals. All improved dramatically following surgical repair. In the following study, we have shown that perilymphatic fistulae can occur in the lateral semicircular canal, and we suggest exploration of this area when indicated.

Adolescent↗
PubMed1976

Perilymphatic fistula and its interest to audiologists.

Forty-one patients who had sudden hearing loss associated with spontaneous perilymphatic fistllas were reviewed in this investigation. A history of physical exertion or an upper respiratory infection prior to the onset of hearing loss strongly suggests the presence of spontaneous perilymphatic fistula. However, absence of such a history does not necessarily preclude the possibility of membrane rupture. A great variation in audiologic and vestibular findings was observed. Tinnitus was present for most patients and vertigo or disequilibrium was reported by some. Findings support the need for surgical exploration in patients with sudden hearing loss when a perilymphatic fistula is suspected. Postoperative success in restoring hearing function in cases with perilymphatic fistula is good if the fistula is closed within two weeks after the initial insult. Delay in closure of such fistulas can cause irreversible loss of hearing.

Adolescent↗
PubMed1989

[Flow kinetics of endolymph in rotational stimulation].

In this paper, experimental and mathematical results are presented, indicating rotatory nystagmus to be caused by endolymph flow in the ampulla of the horizontal semicircular canal. During positive or negative acceleration circular flows may develop within the endolymph system, especially in the ampulla of the horizontal semicircular canal. While being independent of the position of the axis of the horizontally rotating system, the velocity of the flow depends on the radius of the establishing "whirl" in the ampulla. It is demonstrated that, close to the corresponding angular acceleration threshold, the velocity of the tangential flow along the cupula is in the same range as that calculated for a caloric stimulus. Like in our model of calorisation also in rotation there is strong evidence that an endolymph flow directed from crista to cupula in the lateral part of the ampulla causes a nystagmus towards the corresponding side, whereas a flow from cupula to crista causes a nystagmus in the opposite direction. Our results suggest that endolymph flows, evoked either by calorisation or rotation, represent adequate stimuli for vestibular excitability.

Acceleration↗
PubMed1979

Measurement of the hydrostatic pressures of the cochlear compartments.

A micropressure transducer (sensitive 0.1 cm H2O) utilizing a manual servo nulling system and a micropipette (tip diameter 12-20 micron) was designed in order to measure endolymphatic and perilymphatic hydrostatic pressures in the inner ear of the guinea pig. Perilymphatic pressures were measured through the round window membrane in animals in which the ossicular structures had been removed and in those in which the middle ear structures were intact. Endolymphatic pressures were measured after removal of the middle ear structures. There was a significant (p less than 0.001) difference between perilymphatic pressures in the presence (4.7 +/- 0.36 cm H2O) and absence (2.43 +/- 0.22 cm H2O) of the middle ear structures. The endolymphatic pressure was 0.00 cm H2O when measured through the basilar membrane after disruption of the scala tympani, and was 3.34 +/- 0.57 when monitored through the spiral ligament and stria vascularis. In order to verify the accuracy of these measurements, we monitored pressures in animals whose perilymphatic pressures were artificially maintained by an external source. Recoveries were always 95-100% of the artificially applied pressure. The injection of purified cholera toxin into the scala media through the basilar membrane resulted in a significant (p less than 0.001) increase in endolymphatic pressure.

Animals↗