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PubMed1995

Effect of asphyxia on the composition of cationic elements in the perilymph.

To elucidate the role of free radicals in the cochlea, cationic elements in the perilymph of the scala tympani in normal and asphyxic guinea pigs were measured by an inductively coupled plasma atomic emission spectrometer. The concentrations of 7 cationic elements (i.e., calcium, copper, iron, magnesium, phosphorus, lead and zinc) were measured simultaneously in a sample of the perilymph taken before, during and after asphyxia. There was no significant change in these cationic elements during asphyxia for 3 min. In contrast to the stationary level during asphyxia, the iron concentration was significantly elevated at 5 min after re-ventilation following asphyxia and decreased rapidly toward the pre-asphyxic level thereafter, although no significant change was observed in other cationic elements. These results were comparable to the theory of non-protein-bound iron accumulation produced by an O2-dependent mechanism during re-perfusion.

Animals↗
PubMed1996

Electrochemical potentials and potassium concentration profiles recorded from perilymph, endolymph and associated inner ear tissues in adrenalectomized rats.

This study evaluated the electrochemical potentials and potassium concentration (Ck+) profiles in the perilymph, endolymph, marginal cells, and spiral ligament of adrenalectomized rats in which endogenous corticosteroids had been removed. Electrochemical potentials recorded at the four cochlear sites were not affected by adrenalectomy (ADX). Ck+ was greater in the endolymph of the ADX animals as compared to control animals. Additionally, there was an increase of Ck+ in the marginal cells, perilymph, and spiral ligament tissues of the ADX animals as compared to control animals, although the observed increases were not statistically significant. In a previous study (Ma et al., 1995a), it was found that potassium levels in the blood plasma of ADX animals were higher than those identified in normal rats; thus, ADX may have a systemic effect on Ck+ that is detectable in both tissues and fluids within the cochlea. Even though Ck+ was elevated within the cochlea in the ADX model, the functional response of the inner ear, as assessed electrophysiologically, was not altered.

Action Potentials↗
PubMed1998

AP30, a differential protein marker for perilymph and cerebrospinal fluid in middle ear fluid, has been purified and identified as human apolipoprotein D.

Using two-dimensional (2-D) gel electrophoresis, human perilymph and cerebrospinal fluid have been shown to be highly enriched for an acidic protein with MR 30,000, we designated it as AP30. The protein exhibits charge heterogeneity, with at least eight isoforms visible between pI 4.5 to 5.5 on 2-D gels. Purification of the protein was carried out by ammonium sulfate precipitation, polybuffer exchanger column chromatofocusing, and acetone fractional precipitation. The resulting preparation also contains eight spots in the acidic area of 2-D gels, and one broad band located at Mr 30,000 by SDS-PAGE. Digestion of AP30 with neuraminidase causes the isoforms to shift to a more basic position and to consolidate into two primary spots, indicating that AP30 is a variably sialylated glycoprotein. Amino acid analysis of AP30 revealed an amino acid content very similar to that of human apolipoprotein D. Attempts to determine the amino acid sequence demonstrated that the N-terminus is blocked. Edman sequencing of two peptide fragments, generated by cyanogen bromide cleavage of AP30, both revealed sequences having 100% identity to human apolipoprotein D. Western blot analysis of AP30 with the antibody against authentic human apolipoprotein D demonstrated a high degree of cross-reactivity. These studies indicate that AP30 from human perilymph and cerebrospinal fluid is a member of the apolipoprotein D family.

Amino Acid Sequence↗
PubMed1997

Efflux of glutamate into the perilymph of the cochlea following transient ischemia in the gerbil.

Using a microdialysis technique followed by an enzyme cycling analysis, we measured changes in the glutamate levels in the perilymph of gerbil cochleae before, during and after transient ischemic insult. The basal glutamate level in perilymph was 0.35 +/- 0.22 pmol/microl. An almost immediate and continuous rise in the level of glutamate occurred after the ischemic insult, which advanced even further after recirculation; the average concentration was higher than 40 pmol/microl 55 min after recirculation. The compound action potentials (CAP) monitoring the auditory function totally disappeared after ischemic insult. However, CAP reappeared after recirculation; the threshold for acoustic stimulation was higher than that observed at the pre-ischemic state.

Acoustic Stimulation↗
PubMed2003

Late dosing with ethacrynic acid can reduce gentamicin concentration in perilymph and protect cochlear hair cells.

A key factor in the well-known interaction between ethacrynic acid (EA) and aminoglycoside antibiotics (AABs) is disruption of the blood-labyrinth barrier (BLB), leading to rapid entry of EA and AABs into the cochlear fluids. The idea that the blood-labyrinthine fluid concentration gradient might be utilized in a protective manner was tested in the current experiment. We hypothesized that administering EA when gentamicin (GM) levels are higher in the cochlea than in the blood might actually reduce cochlear damage by permitting efflux of GM from the cochlear fluids into the bloodstream, down a concentration gradient and across a temporarily disrupted BLB. Guinea pigs received 1, 11, 14 or 20 injections of GM (125 mg/kg i.m.). Approximately half of the animals also received a single injection of EA (40 mg/kg i.v.) either concurrently or 12-18 h after the last GM injection. Concurrent injection of EA significantly increased GM concentration in serum and perilymph at all time points sampled (2.5, 5-8, and 12 h post injection). Compared to animals that received GM only, animals that received a delayed injection of EA had a significantly lower GM concentration in perilymph, lower thresholds of the compound action potential, and less outer hair cell loss. Collectively, the evidence suggests that EA can reduce GM ototoxicity if it is administered 12-18 h after GM, but the mechanism remains to be elucidated. The results may have implications for the clinical management of aminoglycoside ototoxicity in humans, as well as for understanding the mechanisms underlying AAB/EA interactions.

Action Potentials↗
PubMed1997

An unusual case of presumed perilymph fistula.

Perilymph fistulae have been described for over 30 years and yet there are no universally accepted diagnostic criteria or treatment regimes for them. This paper describes an unusual case of a presumed traumatic perilymph fistula and discusses its treatment and prognosis in relation to previous studies.

Adult↗
PubMed1999

Suppression of post-caloric nystagmus in experimental perilymph fistula.

Albino guinea pigs (n = 28) were used to establish an animal model of the perilymph fistula (PLF) by suctioning 2-4 microliters of perilymph via the left round window membrane. At times varying from 1-3 weeks post-operatively, 9 animals had no caloric response, 5 had a weak caloric response and none had post-caloric nystagmus (PCN). The remaining 14 animals had caloric irregularity in lesioned ears; 12 of these (87%) also did not have PCN. Morphological study of the latter revealed an intact contour of the membranous labyrinth in the lateral semicircular duct and partial collapse of the utricular wall, a condition called the "floating labyrinth". We therefore believe that effective suppression of PCN in the experimental PLF is due to failure in short-term adaptation, caused by lesions in the peripheral vestibular organs, such as the floating labyrinth.

Animals↗
PubMed1983

Dependence of noise-induced hearing loss upon perilymph magnesium concentration.

Noise-induced hearing loss (NIHL) is significantly greater in rats fed a magnesium-deficient diet than in rats on a magnesium-rich diet. The hearing loss was found to be negatively correlated with the magnesium concentration of the perilymph. It is suggested that also in man, the magnesium concentration in the perilymph may be of importance in determining susceptibility to NIHL.

Animals↗
PubMedDate not supplied

Cortisol levels in the human perilymph after intravenous administration of prednisolone.

Cortisone is used in various inner ear disorders such as sudden hearing loss. However, it is not known if the doses of prednisolone employed in therapy increase the cortisol level in the inner ear. To evaluate the level of cortisol within the perilymph after intravenous administration of 125 and 250 mg of prednisolone, serum and perilymph samples of 29 consecutive patients with clinical otosclerosis subjected to stapedectomy were collected. Cortisol levels were determined by RIA. The perilymphatic cortisol level was significantly increased in the group with 250 mg of prednisolone while the perilymphatic cortisol levels were not significantly different between the control group and the patients treated with 125 mg. Although the therapeutic dose of prednisolone is not known, we conclude that the application of 250 mg has a greater impact on the inner ear than 125 mg.

Adult↗
PubMedDate not supplied

Minute perilymph fistulas: vertigo and Hennebert's sign without hearing loss.

The clinical entity characterized by episodic vertigo and a positive Hennebert's sign in patients without hearing loss is described. The history of perilymph fistulas is reviewed. Minute perilymph fistulas of the oval window were documented surgically in five consecutive patients with this syndrome. All experienced relief of their symptoms after surgical correction.

Adult↗
PubMed1989

Round window membrane and perilymph in experimental otitis media with effusion.

To investigate the influence of middle ear effusion (MEE) on perilymph (PL), an experimental otitis media with effusion (OME) was manufactured in chinchillas by injecting the tympanic cavity with immune complexes. The presence of MEE lasted for up to 9 days after the injection of immune complexes. Perilymph was aspirated on the fourth, tenth, and 21st days after the inoculation. The mean concentrations of albumin, immunoglobulin G, histamine, and prostaglandin E2 (PGE2) were significantly greater in PL from ears with induced OME than in that from normal control ears. The 3H-PGE2 placed on the round window membrane of pathologically affected ears passed into PL in significantly greater amounts than in normal control ears. The findings indicate that the immune complexes placed in the middle ear cavity affect the biochemical milieu of PL, and that MEE is a result of immune complexes.

Albumins↗
PubMed1991

Pressure relationship between perilymph and endolymph associated with endolymphatic infusion.

The pressure difference between the perilymph and the endolymph following infusion of artificial endolymph into the endolymphatic space was studied in guinea pigs. Both the perilymphatic and the endolymphatic pressures were measured simultaneously with use of two sets of a servo-nulling system. Endolymphatic infusion caused pressure increases in both the endolymphatic and the perilymphatic spaces, but no measurable pressure difference between them. Soon after the endolymphatic infusion, both pressures returned nearly to the initial levels. We conclude that 1) the endolymphatic and the perilymphatic pressures are very closely related, and 2) if a physiologically significant pressure difference exists between endolymph and perilymph in endolymphatic hydrops, it is below the resolving power of the methods used in this study (+/- 0.1 mm Hg).

Animals↗
PubMed1995

Recovery of caloric function in experimental perilymph fistula.

Twenty of 46 guinea pigs with experimental perilymph fistula that showed canal paresis on an ice water caloric test during the first week after operation were studied on the following days to observe the progression and final outcome of the caloric test. Two weeks after operation, 12 animals showed persistent canal paresis, whereas 8 animals developed a normal caloric response. Resolution of the caloric response progressed from canal paresis, via caloric irregularity, to a final return of normal caloric response. Morphological study of animals with recovery of caloric function shows healing of the previously ruptured membrane, with preservation of the contour of the membranous labyrinth in the lateral semicircular duct, and intact sensorineural elements. Recovery of caloric function may serve not only as an important diagnostic sign in patients with healed perilymph fistula, even without surgical proof, but also as an expectation for the recovery of hearing loss.

Animals↗
PubMed1987

Quantitative diagnostic test for perilymph fistulas.

Clinically, the definitive diagnosis of perilymph fistulas can only be made by tympanotomy. Results of various fistula tests based upon the vestibulo-ocular reflex have not correlated well with findings during tympanotomy. A new fistula test has been developed based upon vestibulo-spinal responses. By systematic removal of both visual and support-surface orientation references from the subject--leaving only vestibular control of postural reflexes--patients with perilymph fistulas demonstrated an increased (sometimes phase-locked) postural sway in response to sinusoidal changes in external auditory canal pressures. Results from 100 consecutively operated ears (64 patients)--77 of whom underwent preoperative and postoperative moving-platform fistula tests--indicate that the test sensitivity is 97 percent for this highly selective patient population. Absolute specificity could not be determined because, on patients without clinical indications for surgery, tympanotomy is contraindicated.

Adolescent↗
PubMed1990

Is there consensus in perilymph fistula management?

A perilymph fistula is an abnormal communication between the inner ear fluids and the middle ear space. This article identifies areas of agreement in perilymph fistula management based upon 167 questionnaire responses from active surgeons of the American Otological Society and the American Neurotological Society. The average respondent performed 4.6 fistula explorations among 197 otologic surgeries (some of these were myringotomies) per year. The following statements represent areas of general agreement. The single most important feature of the history is previous trauma or barotrauma. At present no test can replace clinical judgment; however, despite sound judgment and sophisticated testing, it is very difficult to document the presence or absence of a fistula preoperatively. Most often the diagnosis is based on the total clinical picture: history, physical examination, and laboratory testing.

Ear Diseases↗
PubMed1990

Vestibular effects of chronic perilymph fistula in the cat.

Chronic, unilateral perilymph fistulae were created in cats by removal of the round window membrane and placement of a tympanostomy tube into the round window. Rotary chair, fistula, caloric, and vestibulospinal tests were performed before and after fistulization, and periodically for 2 weeks. At 2 weeks, patency of the fistula was documented by fluorescein injection into the spinal fluid and visualization of leakage into the middle ear bulla via the fistula. All the cats had a patent fistula at 2 weeks, but one of the three cats had a greater perilymph leak than the others. The cat with the more active leak had a spontaneous nystagmus toward the side of the fistula on the first postoperative day; this changed to nystagmus toward the opposite side by the third postoperative day. The other cats had a spontaneous nystagmus toward the opposite side from the first postoperative day. Most abnormal test results returned to normal in the first week after fistulization. Histologic study of the temporal bones revealed that the cat with the greater leak had a wider cochlear aqueduct than the other cats.

Animals↗
PubMed1990

Bilateral spontaneous perilymph fistulae: a diagnostic and management dilemma.

In this article, we present a case of bilateral perilymph fistulae. This entity is rare and always presents a diagnostic problem. Bilateral perilymph fistulae are more common in children and should be suspected when bilateral ear symptoms and congenital temporal bone radiographic anomalies are present. Previous trauma or barotrauma may be absent. When a patient manifests bilateral ear symptoms and a fistula has been identified and repaired in one ear, a second fistula should be suspected in the contralateral ear, especially if the fistula test is positive.

Adult↗
PubMed1983

Hydrops following perilymph fistula repair.

A series of 15 ears were explored for perilymph fistulas. Fifteen fistulas were found in 13 ears. Two cases are presented which developed hydrops-like symptoms only after closure of their fistulas. Closure of the other patients' fistulas was successful in relieving vertiginous symptoms, although hearing seldom improved. There were no significant complications of surgery. Fat failed as a graft material 4 of 10 times, whereas vein and perichondrium were not associated with recurrence of symptoms. The ENG-fistula test, as described by Daspit and associates, correctly predicted the presence or absence of a fistula in 7 of 8 ears tested. Hennebert's sign correctly predicted fistulae in 2 ears, and Hennebert's symptom was associated with proven fistulae in 9 of the 10 times it was present. Because of the low morbidity and the high success rate of surgery, a patient with a history suggestive of a perilymph fistula should have exploratory tympanotomy, particularly if the ENG-fistula test is positive.

Adult↗