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PubMed1981

Perilymph fistulas.

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.

Cerebrospinal Fluid↗
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↗
PubMed2006

How does the inner ear generate distortion product otoacoustic emissions?. Results from a realistic model of the human cochlea.

There is general agreement that distortion product (DP) otoacoustic emissions elicited by stimuli up to 80-90 dB SPL originate from the saturating nonlinearity of the cochlear amplifier at the basilar membrane site, S, where the responses to the two primary tones overlap. There are, however, different interpretations of how the inner ear transmits the effects of this process to the stapes. The supporters of transmission line models assert that the phenomenon depends upon two main mechanisms: (1) the generation of forward and backward traveling waves (TWs) by DP oscillations at S; (2) the backward propagation of wave components reflected by 'micromechanical impedance perturbations' at the sites where the DP TWs peak. However, quantitative predictions based on this view are still lacking. In contrast, here we show, using a nonlinear hydrodynamic model, that the emissions are propagated almost instantaneously through the fluid.

Basilar Membrane↗
PubMed1982

Fluorescein kinetics in perilymph and blood: a fluorophotometric study.

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.

Animals↗
PubMed1985

Biochemical differences between perilymph, cerebrospinal fluid and blood plasma in the guinea pig.

Seven selected biochemical substances were systematically analyzed in perilymph (PL), cerebrospinal fluid (CSF) and blood plasma or serum of anesthetized guinea pigs in order to compare the composition of these fluids with regard to the origin and biochemical nature of PL. Compositional differences between the fluids were expressed by PL/CSF and PL/plasma concentration ratios of the chemical components measured. Contrary to the prevailing notion, the results suggest that the specific biochemical composition of PL corresponds neither to that of CSF nor to that of a simple ultrafiltrate of blood plasma. Furthermore, except for the total protein concentration, no significant differences were found in the composition of PL between the scala tympani and scala vestibuli.

Animals↗
PubMedDate not supplied

Evidence for a perilymphatic origin of the endolymph: application to the pathophysiology of Ménière's disease.

The origin of the endolymph was elucidated by kinetic studies of the entry of water and electrolytes into endolymph and perilymph after intravenous administration of radioactive tracers in rats. The compartmental analysis of the data and the comparison of this study with the results of Konishi and associates (Acta Otolaryngol (Stockh) 86, 22-34 and 176-184, 1978), using perilymphatic perfusion of tracers, indicate that perilymph rather than plasma may be considered the precursor of endolymph. Since the cochlear epithelium was found to be freely permeable to water, an alteration of electrolyte transportation across the membranous labyrinth may be involved in the pathophysiology of Ménière's disease. Chloride transport across the cochlear epithelium was investigated using acetazolamide, a specific carbonic anhydrase inhibitor.

Acetazolamide↗
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↗
PubMed2005

Effect of fluid forcing on vestibular hair bundles.

A dynamic 3-D hair bundle model including inertia and viscous fluid drag effects based on the finite element method is presented. Six structural components are used to construct the hair bundle--kinocilium, stereocilia, upper lateral links, shaft links, tip links, and kinocilial links. Fluid drag is distributed on the surface of cilia columns. Bundle mechanics are analyzed under two distinct loading conditions: (1) drag caused by the shear flow of the surrounding endolymph fluid (fluid-forced), (2) a single force applied to the tip of the kinocilium (point-forced). A striolar and a medial extrastriolar vestibular hair cell from the utricle of a turtle are simulated. The striolar cell bundle shows a clear difference in tip link tension profile between fluid-forced and point-forced cases. When the striolar cell is fluid forced, it shows more evenly distributed tip link tensions and is far more sensitive, responding like an on/off switch. The extrastriolar cell does not show noticeable differences between the forcing types. For both forcing conditions, the extrastriolar cell responds serially--the nearest tip links to the kinocilium get tensed first, then the tension propagates to the farther tip links.

Algorithms↗