Production of inner ear fluids.
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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.
For systematic characterization of cochlear perilymphatic (PL) fluid proteins and to compare the complex protein mixtures of PL fluid, cerebrospinal fluid (CSF) and blood plasma, we subjected eight postmortem PL fluid samples to two-dimensional (2D) electrophoresis. To avoid contamination of perilymph by blood and blood plasma, the samples were taken immediately after death and analyzed by keeping to certain selection criteria. When compared with CSF, PL fluid in the scala vestibule was found to have an albumin content of approximately 1-2g/l, or 10 times the level of CSF albumin. Due to the small volume of the sample obtained, it was not possible to concentrate the PL fluid. As a result, protein spots in the 2D-gel could only be detected with a highly sensitive silver stain. Visual inspection of the resulting 2D-electrophoretograms showed that most of the "CSF-specific" protein clusters were present in the PL fluid pattern.
A perilymph fistula is an abnormal communication between the fluids surrounding the membranous labyrinth and the middle ear space. Because of the potential hazards of meningitis, permanent hearing loss, and occasionally incapacitating vestibular symptoms, early recognition and prompt repair of the perilymph leak is important. One hundred thirty three cases of perilymph fistulas are presented, stressing the clinical characteristics, evaluation, and management of patients with this otologic entity. The historical and contemporary literature on this subject is reviewed. A pathophysiological basis for perilymph fistula formation is presented, based upon certain anatomic, physiologic and mechanical principles involving the temporal bone and surrounding structures. For the purpose of publication, the Materials and Methods and Evaluation sections of the paper have been omitted. These are available from the author upon request in mimeographed form. The interested reader may wish to refer to items 80 and 133 in the Bibliography, previous publications by the author in which the bulk of the data used in the omitted sections can be found.
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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.
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A modified slit lamp fluorophotometer was used to determine fluorescein concentration changes in the perilymph, cerebrospinal fluid and blood of chinchillas after intravenous injection of 0.2 ml of fluorescein sodium. This new technique provides a means of determining quantitative changes of fluorescein concentration in the perilymph without the need to withdraw fluid samples through the round window membrane of cochlear wall. Fluorescein was observed to enter the perilymph between 1 and 2 minutes after injection, and it reached its peak concentration in the mean time of 23 minutes. The mean peak concentration was 4.20 X 10-6 g/ml. Both increasing and decreasing fluorescein concentration changes in the perilymph followed an exponential time course. Although the observations of cerebrospinal fluid fluorescence were thought to represent a composite of the fluorescence of the cerebrospinal fluid itself and the underlying brain stem blood vessels, the peak fluorescence did not exceed that observed in the perilymph. These observations support the view that most of the perilymph is produced in the cochlea by ultrafiltration from the cochlear blood vessels. The slit lamp fluorophotometer appears to be a satisfactory means of recording fluorescein concentration changes in the perilymph without disturbing the cochlear physiology by penetrating the labyrinth to obtain fluid samples.