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PubMed1980

Diagnosis of perilymph fistula using ENG and impedance.

The presence of perilymph fistula has been difficult to determine because of the lack of efficient and reliable testing methods. The condition is suspected on the basis of history alone and confirmed by surgery. This paper details a quick, reliable procedure called the ENG fistula test, using impedance bridge for pressure change and electronystagmography to aid the establishment of nystagmus and dizziness. To evaluate this procedure, a combination of tests were performed, including Valsalva maneuver, tragal compression, and pneumatic otoscopy, which were previously considered helpful in the diagnosis of fistula. Of them, Valsalva maneuver and tragal compression proved inconclusive; pneumatic otoscopy proved to be helpful. In comparison, however, the ENG fistula test proved most valuable, with results surgically confirmed in 90.8% of cases in this series. This study involved 74 patients whose primary complaint was dizziness. Only some patients simultaneously experienced hearing lows. Included are 5 patients whose positive ENG fistula test results and 15 whose negative test results were confirmed by surgery. Selected case histories are presented.

Acoustic Impedance Tests↗
PubMed1990

Early alterations of cochlear function in experimental perilymph fistulas.

Alterations of cochlear function secondary to perforation of the round window membrane in guinea pigs were expected to reveal sensitive and/or specific audiometric parameters in perilymph fistulas. A perforation of the round window membrane either did not affect acoustic compound action potential thresholds, or induced a delayed, possibly conductive, inner ear hearing loss. Also, evoked suprathreshold responses deteriorated progressively and independently of the increase of compound action potential thresholds. A sudden (conductive) hearing loss and a poor response to suprathreshold stimulation might indicate inner ear damage secondary to a perilymphatic fistula.

Animals↗
PubMed2006

Effects of CO2/HCO3- in perilymph on the endocochlear potential in guinea pigs.

The effect of CO(2)/HCO(3)(-) on the endocochlear potential (EP) was examined by using both ion-selective and conventional microelectrodes and the endolymphatic or perilymphatic perfusion technique. The main findings were as follows: (i) A decrease in the EP from approximately +75 to approximately +35 mV was produced by perilymphatic perfusion with CO(2)/HCO(3)(-)-free solution, which decrease was accompanied by an increase in the endolymphatic pH (DeltapH(e), approximately 0.4). (ii) Perilymphatic perfusion with a solution containing 20 mM NH(4)Cl produced a decrease in the EP (DeltaEP, approximately 20 mV) with an increase in the pH(e) (DeltapH(e), approximately 0.2), whereas switching the perfusion solution from the NH(4)Cl solution to a 5% CO(2)/25 mM HCO(3)(-) solution produced a gradual increase in the EP to the control level with the concomitant recovery of the pH(e). (iii) The perfusion with a solution of high or low HCO(3)(-) with a constant CO(2) level within 10 min produced no significant changes in the EP. (iv) Perfusion of the perilymph with 10 microg/ml nifedipine suppressed the transient asphyxia-induced decrease in EP slightly, but not significantly. (v) By contrast, the administration of 1 microg/ml nifedipine via the endolymph inhibited significantly the reduction in the EP induced by transient asphyxia or perilymphatic perfusion with CO(2)/HCO(3)(-)-free or 20 mM NH(4)Cl solution. These findings suggest that the effect of CO(2) removal from perilymphatic perfusion solution on the EP may be mediated by an increase in cytosolic Ca(2+) concentration induced by an elevation of cytosolic pH in endolymphatic surface cells.

Ammonium Chloride↗
PubMedDate not supplied

A survey of the effects of loop diuretics on the zonulae occludentes of the perilymph-endolymph barrier by freeze fracture.

The acute (30 min) effects of the loop diuretics piretanide, ethacrynic acid, bumetanide, furosemide, and azosemide, and the chronic (8 days) effects of furosemide and bumetanide on the zonulae occludentes (tight junctions) of the perilymph-endolymph barrier in the stria vascularis and in Reissner's membrane of the basal cochlear turns were studied by freeze-fracture. Quantitative analysis of their effects indicated that the structural integrity of the barrier was modified by either as increase or a decrease in the number, depth, and density of the strands of the tight junctions of the strial marginal cells. Only azosemide appeared to modify the tight junctions between the epithelial cells of Reissner's membrane, but it had little effect on the strial junctions. The tight junctions between the basal cells of the stria appeared to be the least affected by the various loop diuretics, although piretanide appeared to increase randomly the intercellular spaces lying between the strands.

Animals↗
PubMedDate not supplied

Perilymph oxygenation in sudden and progressive sensorineural hearing loss.

The perilymphatic oxygen tension of the vestibular perilymph of 34 patients with different inner ear losses were measured with the polarographic method before and after inhalation with carbogen. Two patterns of disturbed perilymphatic oxygenation were observed: 1) Characterized by low initial values of perilymphatic oxygenation and normal response to carbogen inhalation was present in sudden deafness and sudden cochleovestibular loss of inner ear function. 2) Characterized by normal initial values of perilymphatic oxygenation and a low response to carbogen, was found in presence of a slowly progressive sensorineural hearing loss. The significance of the obtained results in regard to the possible vascular pathology of the inner ear is discussed.

Adult↗
PubMed1988

Development of pressure monitoring and controlling system for quantitative analysis of experimentally induced perilymph fistula.

The cause of perilymph fistula, a subgroup of sudden deafness, has not been clearly understood. To study its etiology quantitatively, the inner ear pressure monitoring system with a computer controlled pressurizing device and three types of low-pressure monitoring sensors was constructed and utilized in ex vivo experiments using white guinea pigs. Hypothesizing that cerebrospinal pressure increases cause rupture of the round window membrane, direct and indirect pressurization to cerebrospinal region and simultaneous measurement of inner ear and cerebrospinal pressures were carried out. Ruptures of the round window membranes were seen in the experiments with direct saline infusion into the cochlea when the increment of inner ear pressure exceeded 500 mmH2O. There was no sign of rupture when squeezing abdomen was employed as an indirect pressurization, although cerebrospinal pressure increased.

Animals↗
PubMed1989

Influence of middle ear effusion on perilymph.

To investigate the influence of middle ear effusion (MEE) on perilymph (PL), an experimental otitis media with effusion (OME) was provoked in chinchillas by injecting the tympanic cavity with immune complexes. MEE remained for up to 9 days after the injection of immune complexes. PL was aspirated on the 4th, 10th, and 21st day after the inoculation. The mean concentrations of albumin, IgG, and prostaglandin E2 (PGE2) were significantly greater in PL from OME induced ears than in that form normal control ears. 3H-PGE2 placed on the round window membrane of pathologically affected ears passed into PL in significantly greater amounts than in normal controls. The findings of the present study indicate that MEE affects the biochemical environment of PL. However, this influence was transient and reversible.

Albumins↗
PubMed1995

Effects of experimental round window membrane laceration on the free amino acid profile of perilymph.

To evaluate biochemical changes of inner ear fluid following perilymphatic fistula (PLF), free amino acid (FAA) profiles of perilymph in experimental PLF were determined using high performance liquid chromatography (HPLC). Thirty-five guinea pigs were anesthetized and prepared as PLF models by perforating the round window membrane (RWM) of the left ear. Right ears served as controls. Samples (2 microliters) were aspirated from scala tympani through a RWM perforation. Animals were divided into two groups according to time of sampling following PLF induction: 2-week group (n = 17) and 4-week group (n = 18). Compound action potential (CAP) evoked by 1, 2, 4 and 8 kHz tone bursts were measured using a round window electrode from the left ear before PLF induction and from both ears before final sampling. RWM perforations were completely closed at the time of the final sampling in 8 of 17 animals from the 2-week group, and 15 of 18 animals from the 4-week group. In comparison with that in control ears, concentrations of FAA throughout all profiles was dramatically elevated in the PLF ears with a healed RWM perforation. Most PLF ears with persistent RWM perforation showed minimal differences between 2-week and 4-week groups. No remarkable CAP threshold changes were found at any frequencies tested following PLF induction in both the 2-week and 4-week groups. The unchanged 8 kHz threshold suggests that FAA concentration increases only at the basal end of the cochlea. FAAs accumulate within the basal end of scala tympani in ears with a healed RWM.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Increased fatigue of cochlear potentials after injection of KCl solution in the perilymph.

Cochlear microphonics (CM), action potentials (AP) and endochochlear potential (EP) were recorded on guinea pigs. The introduction of a small quantity of KCl solution (0.1 N) in the perilymph provoked a moderate decrease of CM and AP. During the period of depressed but stable amplitude, the presentation of intense sounds provoked an exaggerated susceptibility to fatigue and a delayed recovery. Similar changes were observed in the evolution of EP. However, the recovery was slower for EP than for CM. The results, as a whole, suggest that the fatigue which is manifested in the depression of cochlear potentials is related to a leakage of potassium ions from endolymph to fluids spaces within the organ of Corti.

Acoustic Stimulation↗
PubMed1976

[Rupture of the round window membrane after slight head injury with flush of perilymph probably caused by large opening of aquaeductus cochleae (author's transl)].

A ringing deaf ear was noticed after slight head injury without loss of consciousness nor fracture of the skull. After performig tympanotomy a ruptured round window membrane with excessive flush of perilymph was found. We might rightly assume that this was induced by a large opening of aquaeductus cochleae combined with the force of inertia of the cerebral liquor and the direction of the push to the round window (blow behind the left ear).

Accidents, Home↗
PubMed1992

Transmission of change in the atmospheric pressure of the external ear to the perilymph.

In experiments using guinea pigs, the middle ear and perilymphatic pressures were simultaneously registered in response to pressure change in the external ear canal. In the first experiment, pressure was slowly loaded in the ear canal in the range of 200 mm H2O to -200 mm H2O. Pressure transmission to the perilymph was smaller when the bulla was open to the outside than when it was closed. It was significantly impaired by disruption of the ossicular chain and especially by closure of the round window. The data indicate that air volume in the middle ear cavity plays an important role in transmission of slowly changing atmospheric pressures. In the second experiment, the eustachian tube was closed and the pressure was changed in the range of 1000 mm H2O to -1000 mm H2O. The middle ear and perilymphatic pressures increased or decreased corresponding to the loading pressure in the range of 400 mm H2O and -200 mm H2O. Beyond these levels, response rate of the middle ear pressure decreased and perilymphatic pressure declined in spite of further increase in loading pressure. The increase in pressure difference between the middle ear and the inner ear might cause disruption of the round and/or oval windows.

Animals↗
PubMed1992

Recurrent meningitis and a congenital perilymph fistula.

In any child with recurrent meningitis, the presence of a congenital perilymph fistula must be entertained. All of the patients must have an audiologic assessment, and if a sensorineural loss is demonstrated, CT of the temporal bones should be performed. CT is excellent in identifying malformations within the temporal bones, fistulous tracts, soft tissue densities in the middle ear, and defects in the tegmen tympani. Although MRI may provide superior discrimination of the audiovestibular and facial nerves and cerebellopontine angle, presently it does not offer any distinct advantages over CT in evaluation of the inner ear. When a fistula is suspected, an exploratory tympanotomy is recommended, and any CSF leak is sealed with muscle.

Cerebrospinal Fluid Otorrhea↗
PubMed1992

Tube-perilymph fistula. An experimental study.

Before exploratory tympanotomy, it is difficult to diagnose an idiopathic perilymph fistula (PLF) because of its variable presentations. An animal model tube-PLF on guinea pigs was established to evaluate the change of the sensitivity of the cochlea function and the value of the postural audiometry in PLF. A fine polyethylene tube (O.D. 0.6mm) was inserted into the scala tympani of the basal turn through the incised round window membrane in 10 experimental guinea pigs, and another 5 as controls. The hearing threshold (HT), action potential (AP) latency for stimulus of 105 dB SPL, difference of HT and AP latency from the test ear down to up were measured by electrocochleography (ECoG) immediately after operation and one week later. The HT, AP latency and postural audiometry showed no significant changes immediately but a significant difference one week later in HT (P less than 0.01) and postural audiometry, the AP latency also presented a significant delay (P less than 0.01). The results showed that the tube-PLF model may be a valuable method for studying chronic PLF.

Action Potentials↗
PubMed2005

Preoperative computed tomography may fail to detect patients at risk for perilymph gusher.

Perilymph gusher (PG) is a very rare occurrence that can lead to an adverse outcome during inner ear surgery. In the absence of a family history of X-linked mixed deafness syndrome, surgeons may have difficulty determining if a patient is at risk preoperatively. Radiographic imaging is often performed in an attempt to identify such a possibility, but there are few data to support the value of negative studies. We conducted a retrospective study of 3 cases of PG in which findings on preoperative high-resolution computed tomography (CT) of the temporal bone had been interpreted as normal. We reviewed these CTs to discern if they did in fact demonstrate any abnormalities that might have indicated a risk of PG, and we found that the original radiologist had missed a dilated internal auditory canal and a deformity of the cochlear modiolus in the affected ear of 1 of these patients. No abnormality was detected on review of the CTs of the other 2 patients. Therefore, we conclude that negative CT findings do not necessarily rule out a risk of PG.

Adult↗
PubMed1990

The dynamic posturographic pressure test for the presumptive diagnosis of perilymph fistulas.

A diagnosis of perilymph fistulas (PLFs) can be made only by identification of repeated accumulation of crystal-clear fluid from an otic capsule defect or labyrinthine window at tympanotomy. It would be highly desirable to base a decision to operate for the diagnosis and management of PLFs on a database that includes quantitative test data, which confirms, with a high probability, a clinical suspicion of PLF. This article reviews progress in the development of a test of the vestibular response to external auditory canal pressure changes as recorded by dynamic posturography. Based on results to date, it appears that a fistula test with dynamic posturography is more sensitive than those based on VOR responses. This may be due to the ability of dynamic posturography to isolate vestibular from both visual and somatosensory influences on motor responses during external canal pressure changes.

Ear Diseases↗
PubMed1989

[Personal experiences with audiometric detection of perilymph fistulas].

Rupture of the round window membrane is thought to be important in the pathogenesis of sudden hearing loss. In 1982 Fraser and Flood proposed an audiometric test to improve the indication for tympanoscopy which, in their experience, verified the diagnosis of perilymph fistulae in a high percentage of cases. Between 1 January 1986 and 30 June 1988 the above test was carried out on 74 patients at the ENT Department of the University of Hamburg. In 41 cases a tympanoscopy was performed. In 13 cases with a positive test result not a single perilymphatic fistula could be found intra-operatively, while in 3 cases of rupture the test was negative. In our experience this test is not helpful for the pre-operative assessment of tympanotomy in sudden hearing loss.

Audiometry↗