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PubMedDate not supplied

Perilymph production and cochlear blood flow.

In rodents at least, the main sources of the perilymph fluid are (1) influx of CSF through the cochlear aqueduct, and (2) blood flow dependent local production within the cochlea. Experimental data are presented that give a ratio of 22:78 percent for those sources. The perilymph production thus derives mainly from the cochlear blood flow. It is concluded that measurements of the perilymph production can be used as indirect measurements of the inner ear blood flow under various experimental conditions. Two experimental examples are referred to.

Acidosis, Respiratory↗
PubMed1979

[Blockage of cochlear aqueduct for examination of perilymph (guinea pig) (author's transl)].

To prevent the perilymph (guinea pig) from contamination with CSF during the sampling the aqueductus cochleae (AC) was blocked by injection of tissue adhesive into the meningeal aperture. The control of an exact blockage of AC was carriedout by examination of perilymph-outflow after opening the cochlea (injection of fluorescein-Na into the CSF-space), analysis of perilymph-protein-concentration, macroscopic and microscopic examination of the temporal bones. In all cochleae we have found the same morphological structures, notwithstanding whether the AC was blocked (for a time from 30 min to 7 weeks) or not: The cochlear aqueduct is filled with a mesh of mesenchymal tissue, which grows more dense towards the cochlear aperture andcontinues into the round window membrane. From scala tympani the AC is always limited by one layer of cells forming a sort of membrane (under light microscope). It seems possible that CSF moves in the inner of the round window membrane between AC and subepithelian space of middle ear mucosa, whereas perilymph of scala tympani is not in direct contact with the flow of CSF. The scala tympanic side of the round window membrane may be a big area for diffusion and there also may be an exchange between CSF and perilymph. The outflow of CSF into the cochlea after experimental opening of the cochlea is an artifact, caused by damage of pressure equilibration between CSF-space and cochlea. 30 min and 5--7 weeks after blockage no morphologicaland electrophysiological alterations from those of the control ears were to be seen. The protein concentration, however, increased significantly 5--7 weeks after blockage from normally about 200 mg/100 ml toalmost the double especially in the scala tympani (see Table 1).

Action Potentials↗
PubMed1977

Physiology and chemistry of cerebrospinal fluid, aqueous humor and endolymph in Squalus acanthias.

By means of the appropriate isotopes injected into the spiny dogfish, Squalus acanthias, the transfer of all major ions into cerebrospinal fluid (CSF), aqueous humor (A) and endolymph (E) was studied. In addition, the effect of raising pCO2 in sea-water upon HCO3- concentration of these fluids was measured. In the several types of experiments, acetazolamide or methazolamide was used to inhibit completely carbonic anhydrase. The rates of fluid formation and ion transfer in CSF and A were fairly close, but those for E were far slower. The general pattern of ion transport in the three fluids were the same, Na+ (or Na+ + K+ in E) entry greater than Cl - entry, and the difference was HCO3-. The greater rate constants for HCO3-, increase in its entry rate by elevation of pCO2, and inhibition of its appearance by the sulfonamides, show that this is a special case of transport; the ion is formed in secretory cells from gaseous CO2 + OH-. Secretory cells at sites of formation of all the fluids contain both carbonic anhydrase and Na+-K+-ATP-ase, which subserve HCO3- formation and Na+ (or K+) transport. Comparison of these results with studies in mammals show that the vertebrate pattern for secretion of these three fluids is well established in the elasmobranch.

Adenosine Triphosphatases↗
PubMed1978

Dizziness: surgical treatment.

The purpose of ths paper is to discuss the various surgical procedures which are available for the treatment of dizziness and vertigo. Special emphasis will be placed on the indications for these operations and the advantages of each. Dizziness is a common complaint of patients seen by general medical physicians and otolaryngologists. At the Otologic Medical Group in Los Angeles about one third of our new patients seek assistance because of dizziness. The etiologies of these various types of dizziness are multiple. It is not the intent of this paper to discuss the differential diagnosis or methods of evaluation. However, it is important to understand the various types of etiological factors as they are important in successful treatment.

Cerebrospinal Fluid Shunts↗
PubMedDate not supplied

Effect of CO2 on the perilymphatic oxygen tension in cats.

A microelectrode with a tip of 100micron permitting recording of the oxygen tension in the perilymphatic space according to the polarographic principle and having a minimal drift of 1-25% per hour has been developed. The effects of apnea, hypo- and hyperventilation as well as those of inhalation of pure oxygen, and CO2 upon the perilymphatic PO2 have been measured by placing the electrode in the perilymph through the fenestrated stapedial footplate of 87 adult cats. The correlation between the arterial PO2 and the perilymphatic PO2 is so close that even hypo- or hyperventilation in presence of air does influence the oxygen content of the perilymphatic space. In view of the effect of the smallest accumulation of alveolar CO2, particular attention has to be paid to the system used for respiration of the experimental animal, when determining the action of drugs or inhaled gas mixtures on the oxygenation of the inner ear fluids. The measurement of the perilymphatic oxygen tension also indicates that the rate of blood flow cannot be used to deduct with accuracy the actual degree of oxygenation of the inner ear fluids.

Animals↗
PubMedDate not supplied

Fluid pathways in temporal bones.

Five temporal bones were serially sectioned and studied concerning spread of erythrocytes and blood-derived precipitate in patients who died from subarachnoid hemorrhage. Erythrocytes followed the natural pathways--the cochlear aqueduct, the cochlear, vestibular, facial and glossopharyngeal nerves, and were demonstrable in the inner ear fluid spaces. The temporal bone marrow spaces were also filled with erythrocytes, particularly in the hypotympanal area. In the microimmunoelectrophoresis, no specific precipitation lines formed between the anti-CSF serum from rabbits and middle ear exudate from human ears with acute otitis media. Although, in animals, middle ear spaces have been shown to be connected to the middle ear space this does not seem to apply to human ears, and CSF fluid components are not involved in the formation of middle ear exudate.

Adult↗
PubMedDate not supplied

Role of perilymph in the early stage of serous otitis.

After injection of an electron-dense tracer into the cerebrospinal fluid (CSF) the particles can be seen within the lymphatic spaces of the middle ear mucosa after a few minutes. They find their way via the well known communication routes from CSF to the perilymphatic spaces of the inner ear. From there they enter through open fluid spaces into the fibrocytic network of the round window membrane which stands in open relationship to the extracellular fluid spaces of the middle ear mucosa. They were drained to the regional lymph nodes by lymphatic vessels. When inducing a serous otitis by experimental obstruction of the Eustachian tube it could be demonstrated that the fluid within the middle ear cavity is partly coming from the CSF and perilymph. Later the healing process of the middle ear epithelium was studied after the onset of serous otitis with and without artificial ventilation of the middle ear.

Animals↗
PubMedDate not supplied

Aminotransferases in post-mortem cochlear fluids.

Aspartate and alanine aminotransferase (ASAT, ALAT) activities were measured in human post-mortem sera, cerebrospinal fluid (CSF), perilymph and endolymph. Due to heart and/or liver morbidity during a terminal illness, the ASAT and ALAT serum activities were considerably increased as compared with normal and both were 20--30 times higher (p less than 0.001) than in CSF or inner ear fluids. CSF and inner ear fluids showed mutually similar values.

Alanine Transaminase↗
PubMed1976

Lactic dehydrogenase of fetal ear fluids under ambient and high-intensity sound.

Lactic dehydrogenase (LDH) was determined in the fluids of the inner ear scalae and the middle ear cavity of fetal guinea pigs near term. Scalar dissimilarities in prenatal perilymph and distinctions between fetal and maternal perilymph suggest functional differentiation between the antenatal scalae vestibuli and tympani, elevated glycolytic activity in the prenatal vestibular channel and primarily aerobic processes in fetal perilymph although anaerobic metabolism is also evident. Disparities between fetal middle ear fluid and prenatal perilymph as well as maternal serum indicate that the former medium is probably not directly derived from either of the latter sources. After experimental treatment consisting of the presentation of high-intensity sound to gravid animals, the total LDH activity of the fetal middle ear fluid decreased.

Acoustic Stimulation↗
PubMedDate not supplied

Pathology of Ménière's disease as it relates to the sac and tack procedures.

The rationale for endolymphatic sac and tack operations is to prevent the further accumulation of endolymph, the former by draining endolymph into extralabyrinthine tissues and the latter by shunting endolymph into the perilymphatic space. While the basic concepts are reasonable enough, the probability of achieving these objectives seems remote. There appears to be adequate clinical evidence, however, to show that these procedures are of therapeutic value in selected cases. It is tempting to speculate that these surgical insults to the labyrinth, with the associated inflammatory and biochemical changes, alter the function of cells which control fluid physiology and thus improve the symptoms of Ménière's disease.

Adult↗
PubMed1976

Symposium: Congenital anomalies of the middle ear. IV. Management of profuse perilymph leak.

Profuse perilymph leak during an otological operation can be controlled by inserting an epidural teflon cannula into the lumbar subarachnoid space and draining away the excess spinal fluid. After about 100 cc is removed the perilymph leak stops, and the oval window can be sealed with a living seal, such as vein, and the operation completed. The catheter is left in the subarachnoid space for about four days, with a bottle on the distal end positioned to remove no more than 150 cc of spinal fluid per day. Results with two patients in which this maneuver was used to control profuse perilymph leak are reported.

Catheterization↗