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PubMed1983

[Effect of changes in electrolyte composition of the perilymph on endocochlear potentials].

Perfusion of the cochlear perilymphatic space was performed in guinea pigs with complete or partial removal of K+, Na+ or Ca++ from the solution. The most obvious changes of the endocochlear potential occurred in the deficiency of Na+ in the perilymph: i. e., after a short increase the potential steadily diminished in accordance with the degree of Na+ deficit in the perilymph. The deficit of K+ in the perilymph caused a lesser and reversible reduction of the potential. The absence of Ca++ in the perilymph did not affect the potential.

Animals↗

PubMed1982

[Antibacterial therapy in surgery of the inner and middle ear. A study of co-trimoxazole penetration into the perilymph (author's transl)].

Studies of the type presented here have rarely been undertaken and should be useful in surgery and pathology of the inner and middle ear. Samples of perilymph were collected during stapedectomy in patients with otosclerosis. In view of the very small volume of perilymph obtainable from each patient's vestibule (2 to 4 microliter), the only assay method that could be used to measure drug levels was thin layer chromatography on silica gel. Despite pooling of the perilymphs of 5 patients, trimethoprim (TMP) levels could not be measured but the authors were able to demonstrate that sulfamethoxazole (SMZ) does penetrate into the perilymph. Since the TMP-SMZ combination (co-trimoxazole) is active against the pathogens usually encountered in middle ear fluids, it is concluded that the drug could be of benefit in the treatment of middle and inner ear infections or after surgical operations on this area.

Adult↗

PubMed1982

[Biochemical analysis of the endolymph and perilymph of the trout (Salmo gairdneri) (author's transl)].

Cerebrospinal fluid, perilymph and endolymph of the saccule, the utricle and the semicircular duct of the trout were prepared from frozen inner ears. Blood was collected after the decapitation of the animal. In all samples of each animal the concentrations of sodium, potassium, protein and glucose were determined. The electrolyte values and the total protein content were used to estimate the purity of a sample. The concentration of sodium is high in perilymph and low in endolymph whereas potassium is high in endolymph and low in perilymph. The differences between perilymph and the cerebrospinal fluid as well as the blood serum are significant. A relative independent production of the inner ear fluids can be assumed.

Animals↗

PubMed1995

Cefuroxime: pharmacokinetics in cochlear perilymph, cerebrospinal fluid, and plasma.

Very little is known about the permeability of contemporary antibiotics through the blood:perilymph barrier. In this study, we measure the concentration of cefuroxime in perilymph, cerebrospinal fluid (CSF), and plasma in the guinea pig following intravenous administration by using the technique of high-performance liquid chromatography. The results of our study demonstrate a higher permeability of cefuroxime in perilymph than in CSF with a similar concentration profile over time in both fluids. This suggests that each of the two fluid compartments has its own drug barrier, with little or no free passage from CSF to perilymph. On the basis of these experimental findings, we feel that cefuroxime has considerable potential as an antibacterial agent for the treatment or prevention of bacterial labyrinthitis.

Animals↗

PubMed1998

Congenital and acquired perilymph fistula: review of the literature.

Perilymph fistula is caused by an abnormal communication between the perilymph space and the middle ear. The etiology is either congenital or acquired. The congenital fistula can be associated or not with clinical symptoms or radiologically detectable abnormalities of the temporal bone. In patients presenting congenital fistula without symptoms or radiologically detectable abnormalities, little malformations of the middle ear may be detected during surgery. The acquired fistula can be caused by iatrogenic trauma, physical injury or erosion. As far as therapy is concerned, surgical treatment can be performed and the perilymph fistula thus represents one of the few causes of sensorineural hearing loss that can be treated surgically. However, the main challenge is the identification of those patients that need to undergo an exploratory tympanotomy, since there are no clinical-audiologic symptoms or radiographic indicators that can be considered pathognomonic of perilymph fistula. The aim of this review of the literature is to define the guidelines for preoperative diagnosis to indicate exploratory tympanotomy both in children and in adults. On the basis of our results, exploratory tympanotomy should be performed in patients with vertigo and/or progressive, sudden or fluctuating hearing loss in association with one or more than one of the following elements: a history of cranial trauma, radiographically detectable abnormalities of the inner ear, congenital malformations of the head, recurring meningitis, positive fistula test. The surgical treatment consists in placing a graft of temporalis fascia or tragal perichondrium and it usually results in a significant improvement of vestibular symptoms and sometimes of the hearing function as well.

Cochlear Aqueduct↗

PubMed2006

[Prediction and management about perilymph gusher in cochlear implantation].

OBJECTIVE: To discuss the clinical experience of prediction and management about perilymph gusher in cochlear implantation. METHOD: Among 327 cases of cochlear implant, eleven recipients were selected by the high resolution computed tomography (HRCT) findings of cochlear malformations and bony fistula on fundus of the internal auditory canal that caused an abnormal connection between subarachnoid and perilymphatic spaces. RESULT: Perilymph gusher was found in all of these 11 recipients during cochlear implantation and was controlled with muscle tissue seal. CONCLUSION: The reason of perilymph gushers in cochlear implantation is that abnormal connection between subarachnoid and internal auditory canal. HRCT can be used to assess the possibility of perilymph gusher in surgery. The safe and rapid surgical method of gusher controlling can avoid complication.

Cerebrospinal Fluid Otorrhea↗

PubMed1996

Fluorescein as an easy, low-cost, indirect, or reverse intraoperative marker to rule out perilymph versus local injection.

Clear fluid found in the dependent portions of the middle ear (round and oval windows) is generally assumed to be perilymph (PL). However, all clear fluid observed at middle ear exploration is not necessarily PL. PL should be distinguished from local injection. An accumulation of the local injection could be confused with perilymph fistula (PLF) diagnosis. There is no standard way of distinguishing perilymph from local injection, as both are clear, watery fluids. Fluorescein, tagged with a mixture of xylocaine and epinephrine (FLOTAX) was used as the local injection in 10 patients undergoing middle ear exploration for possible PLF.FLOTAX was injected into the vascular strip and ear canal skin in routine fashion. Transtympanic endoscopy and special Zeiss custom fluorescein filters were used to document any accumulation of fluid in the dependent portions of the middle ear and confirm whether any fluorescein (from the FLOTAX) was present. The middle ear was checked both before (endoscopically) and after raising the tympanomeatal flap. After the "local" injection, FLOTAX was observed to accumulate in dependent portions of the middle ear before raising the tympanomeatal flap in six of 10 ears. In the other four ears, FLOTAX slowly seeped into the middle ear cleft after the tympanomeatal flap was elevated and manipulated. Fluorescein can be used as an inexpensive, indirect intraoperative marker or "reverse test" for possible PLF. By eliminating a likely and common offender (local injection), any accumulation or reaccumulation of clear fluid that is not fluorescein tagged may more confidently be identified as possibly perilymph. The use of FLOTAX helps eliminate the confusion between the local injection and potential PLF. It does not in any way eliminate the possibility of other transudates from incisions, allergic reactions, or other manipulation of the tympanomeatal flap or middle ear mucosa.

Anesthetics, Local↗

PubMed1976

Alpha 1-antitrypsin activity of perilymph. Occurrence during progression of otospongiosis.

Previous studies by the Adams method demonstrated a strong correlation between hydrolytic enzyme activity of perilymph and progression of bone conduction loss two years preceding stapedectomy. Alpha 1-Antitrypsin was chosen since its activity can be very precisely measured by a radical immunodiffusion technique and since it is one of the enzymes identified in perilymph of patients with active otospongiosis. Samples of 3 mul to 5 mul of perilymph removed during 103 stapedectomies and samples of known alpha 1-trypsin activity were placed on slides coated with alpha 1-antitrypsin serum. The zone of diffusion was stained and measured after 38 hours of incubation. Antitrypsin values were lowest in 24 cases, two with no preoperative bone conduction progression, three with moderate progression of 10 to 15 dB, and 19 with rapid progression of more than 20 dB. They were highest in 36 cases with no progression, and in one case with moderate progression. This study confirms previous reports on the enzymatic activity in otospongiotic disease.

Humans↗

PubMed1976

Osmolality changes in perilymph after systemic administration of glycerin.

Blood osmolality was altered in guinea pigs by intravenous administration of glycerin (glycerol). After glycerin administration, serum osmolality increased rapidly, reaching a plateau within 15 minutes. Perilymph osmolality lagged significantly behind the increase of serum osmolality and equalled serum osmolality only after one hour. While perilymph osmolality responded to changes of serum osmolality, there was some time lag noted in the response of perilymph, suggesting the existence of a blood-labyrinth barrier. It was observed that this barrier is permeably to glycerin and water, suggesting the possibility of transient reduction of hydrostatic pressure in the labyrinth by the injection of an osmotic agent into the systemic circulation.

Animals↗

PubMed1999

Determination of free calcium in guinea-pig cochlea perilymph by capillary electrophoresis with direct injection.

At present, the tinnitus mechanism is still not clear. Our experiments demonstrated that the concentration of free calcium in cochlea perilymph of tinnitus model guinea-pigs is lower than that in normal guinea-pigs. However, the volume of cochlea perilymph is so small that only 5-10 microL of sample can be obtained from each animal. We describe the application of CE to the detection of free calcium in guinea-pig cochlea perilymph. Direct injection was employed in this study. The separation was carried out at 10 kV. The capillary temperature was maintained at 20 degrees C, and indirect UV detection at 214 nm was employed. The samples were vacuum injected for 3 s. The run buffer was 0.005 mol/L imidazole with a pH of 4.30-4.50. The concentration of free calcium in the normal group was found to be in accordance with the reference data. The method has been applied to research on the tinnitus mechanism and for medical treatment.

Animals↗

PubMed1984

On sources of error in the biochemical study of perilymph (guinea-pig).

Contamination of perilymph with other fluids (cerebrospinal fluid, tissue fluid, blood, endolymph) together with sampling, anaesthesia, surgical intervention or food intake of the animals may considerably affect the analytical result. The numerous possible artefacts seem to be the main reason why varying values are given in the literature for the same chemical component of perilymph. This is also partly true of cerebrospinal fluid and blood. The effect of some sources of error on selected chemical components of perilymph, cerebrospinal fluid and blood is briefly summarized.

Anesthesia↗

PubMed1979

Alteration of oxidative enzymes (LDH and MDH) in perilymph after noise exposure.

Chinchillas were exposed to noise (123 dB, 1/2 h, 700--2800 Hz). The activity of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) was studied immediately after exposure or 1, 7, 14, 21, or 28 days later. LDH activity in perilymph doubled immediately after exposure, gradually decreasing to control values in about a month. The activity of MDH not only doubled immediately after the exposure but continued to rise for at least another 24 h, reaching a peak value of 3.5 times normal at 24 h. The activity was still 1.6 times normal even after a month of recovery. The enzyme activity of serum and CSF remained within the control range throughout the experimental period except for an initial increase of serum enzyme activity due to anesthetic. The results demonstrate that the morphological changes induced by a noise exposure that is known to produce permanent threshold shift (PTS) are reflected in a significant elevation of oxidative enzymes in perilymph. Possible mechanisms of the elevation of enzymes in perilymph are discussed.

Animals↗

PubMed1995

Distribution of cisplatin in perilymph and cerebrospinal fluid after intravenous administration in the guinea pig.

The concentration of free cisplatin was followed in plasma, scala tympani perilymph and cerebrospinal fluid (CSF) after an intravenous injection (12.5 mg/kg) in guinea pigs. Liquid chromatography with postcolumn derivatization was used for quantitative determination of the drug. The distribution of cisplatin to CSF was fast; at 10 min after drug administration the concentration was 7 micrograms/ml and the CSF:plasma ratio was 0.37. Cisplatin seems to distribute more slowly to the perilymphatic compartment. The highest concentration measured was 4 micrograms/ml at 20 min after the injection, and the perilymph:plasma ratio was 0.40 at that time. The concentration-time curves generated for cisplatin in perilymph and CSF were similar. No accumulation in the perilymphatic compartment or CSF was observed.

Animals↗

PubMed1991

The reaction of the guinea pig cochlea to perforations of the round window membrane with and without perilymph aspiration.

The influence of simple opening of the round window (RW) membrane and the effect of aspiration of perilymph on the electrophysiological characteristics of the cochlea was tested in guinea pigs by measurement of the compound action potentials. We found that perforations of the RW membrane failed to lead to either short-term or long-term damage in cochlear function. There was only a slight spontaneous escape of perilymph but without measurable functional loss. Additional aspiration of perilymph led to entry of air into the basal turn and to an immediate loss of function of the cochlea. This regressed within 4 weeks in the middle- and low-frequency ranges. Measurable long-term damage persisted only in the high-frequency ranges. We attribute contradictory results of other authors to methodological errors which we avoided by a specific selection of healthy animals and the development of standardized operation, recording and measurement procedures.

Acoustic Stimulation↗

PubMed1975

[The significance of inner ear fluid (perilymph) in forensic medicine (author's transl)].

An original method for collecting the perilymph in the inner ear by chiselling the pyramid of the temporal bone is presented; From 300 to 350 mul of fluid may be obtained each time. Various types of determination were performed on 399 human cadavers. The alcohol level was tested in 140 cases, the ABO(H) group antigens were determined in 89 cases, the phenotypes of the gamma-globulin (1) group system in 152 cases, and the alpha1-antitrypsin (Pi) system in 18 cases. Determinations of the alcohol level in the perilymph has been confirmed to be useful, as they allow not only determination of the degree of intoxication in cadavers in an advanced state of decomposition, but also by comparing the alcohol concentration in the cerebrospinal fluid, the vitreous humour, and the blood, the phases of elimination and absorption of alcohol may be more precisely determined. It was also found that the perilymph is a good medium for the determination of the group antigens of the red blood-cells and the gamma-globulin system, the serum and the alpha1-antitrypsin enzyme. These data suggest that the method may be more widely used in various forensic medical tests.

Forensic Medicine↗

PubMed1991

Magnitude of the negative summating potential varies with perilymph calcium levels.

Previous results demonstrated that nimodipine, an L-type of Ca2+ channel antagonist, abolished the negative summating potential (SP) recorded from anesthetized guinea pigs (Bobbin et al., 1990), suggesting that Ca2+ is involved in generation of the negative SP. Therefore we examined the effect of changing concentrations of perilymph Ca2+ on this cochlear potential. Perilymph spaces of guinea pig cochleae were perfused with artificial perilymph solutions containing zero mM Ca2+, zero mM Ca2+ with 2 mM EGTA, 30 mM Mg2+ and increasing levels of Ca2+ (2, 4, 8, 16 mM) at a rate of 2.5 microliters/min for 10 min. Immediately after each period of perfusion the compound action potential of the auditory nerve (CAP), cochlear microphonics (CM) and the negative SP evoked by 10 kHz tone bursts of varying intensities were recorded from a wire inserted in the basal turn scala vestibuli. Decreasing the level of Ca2+ decreased the magnitude of the negative SP, whereas increasing the level of Ca2+ progressively increased the magnitude of the negative SP. Mg2+ (30 mM) suppressed the CAP to the same extent as zero mM Ca2+ with 2 mM EGTA, but only slightly increased the magnitude of the negative SP. These results support the hypothesis that Ca2+ and L-type Ca2+ channels are involved in the function of the hair cells and the generation of the negative SP. Mg2+ appears to be a selective antagonist of the Ca2+ channel involved in transmitter release.

Animals↗

PubMed1992

Metallic elements in the perilymph measured with an inductively-coupled plasma atomic emission spectrometer.

Metallic elements in the perilymph of the scala tympani in normal and acoustically overstimulated guinea pigs were measured using a new method, an inductively-coupled plasma atomic emission spectrometry. The concentrations of phosphorus and eight metallic elements, i.e. calcium, copper, iron, potassium, magnesium, sodium, lead and zinc were measured simultaneously in a 2 microliters sample of perilymph. The mean concentration values of calcium, copper, iron, magnesium, phosphorus, lead and zinc were 2.03 mM, 38.5 microM, 69.3 microM, 0.822 mM, 0.851 mM, 43.5 microM and 25.0 microM, respectively. There was no significant effect of acoustic overstimulation on the concentrations of these elements except for magnesium, which decreased significantly after the exposure to a intense sound (2 kHz, 115 dB SPL) for 15 min. This is the first report describing the synchronous determination of metallic poly-elements, including copper, iron, lead and zinc, in the perilymph.

Acoustic Stimulation↗

PubMed2003

Effect of round window membrane application of nitric oxide on hearing and nitric oxide concentration in perilymph.

Nitric oxide (NO), a free radical, has been found to be important in the development of middle ear effusions. However, the effect of NO in the middle ear effusion on cochlear function and on perilymph concentrations of NO has not been reported. We placed S-nitroso-N-acetylpenicillamine (SNAP), a NO donor compound, on the round window membrane (RWM) of adult chinchillas. Auditory brainstem response (ABR) thresholds were measured before and after the placement of SNAP on the RWM and hourly for 8 h after SNAP placement. Samples of perilymph were collected 2 h after application of SNAP and were assayed for total nitrate and nitrite, the end products of NO. Experimental ears demonstrated significant ABR threshold elevations after 5 h and elevated nitrate/nitrite in the perilymph. These findings suggest that NO present in the middle ear passes through the RWM into the inner ear and can cause significant hearing loss.

Animals↗