Correlation Between Adenoid Hypertrophy, Tympanometry Findings, and Viscosity of Middle Ear Fluid in Chronic Otitis Media With Effusion, Southern Oman.

Otitis media with effusion is a common cause of diminished hearing in children younger than 12 years. Hypertrophy of adenoids is one of the commonest etiologies of this condition. It has been mentioned that with increased size of the adenoid tissue, the more likely the incidence of fluid in the middle ear. The aim of this study was to find whether there is a correlation between adenoid size, tympanometric findings, and type of fluid in the middle ear irrespective of disease duration. This is a prospective study done on 100 pediatric patients (12 years and less) presented with chronic otitis media with effusion (COME) and adenoid hypertrophy from July 2015 till July 2017. Cases with tympanometry evidence of COME (B, Cs) and adenoid hypertrophy seen by nasal endoscopy were included. Adenoid size was graded and correlated with the type of tympanometry and type of fluid in the middle ear. Sixty male children and 40 female children were involved. Age ranged from 3 to 12 years with a mean of 7.19 ± 2.489 years. Highly significant relation existed between grade 4 adenoid hypertrophy and mucoid nature of middle ear fluid (P value = .000). There is a highly significant relation between adenoid hypertrophy grade Ⅳ and type B tympanometry. There is a highly significant relation between adenoid size and nature of middle ear fluid irrespective of the duration of complaints, where grade Ⅳ adenoid hypertrophy showed more increase in middle ear effusion viscosity making adenoid size a very important predictor for the tympanometry type and the nature of the fluid in the middle ear.

Cochlear Outer-Hair-Cell Power Generation and Viscous Fluid Loss.

Since the discovery of otoacoustic emissions and outer hair cell (OHC) motility, the fundamental question of whether the cochlea produces mechanical power remains controversial. In the present work, direct calculations are performed on power loss due to fluid viscosity and power generated by the OHCs. A three-dimensional box model of the mouse cochlea is used with a feed-forward/feed-backward approximation representing the organ of Corti cytoarchitecture. The model is fit to in vivo basilar membrane motion with one free parameter for the OHCs. The calculations predict that the total power output from the three rows of OHCs can be over three orders of magnitude greater than the acoustic input power at 10 dB sound pressure level (SPL). While previous work shows that the power gain, or the negative damping, diminishes with intensity, we show explicitly based on our model that OHC power output increases and saturates with SPL. The total OHC power output is about 2 pW at 80 dB SPL, with a maximum of about 10 fW per OHC.

Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs.

CONCLUSIONS: Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. OBJECTIVES: Cochlea fluid pH is highly dependent on the HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF. The purpose of this study was to elucidate the effect of positive hydrostatic inner ear pressure and application of a vasodilator and vasoconstrictor of cochlear vessels on the pH of the endolymph and perilymph. METHODS: The authors performed animal physiological experiments on 30 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig cochlea. During the topical application study, scala vestibuli perilymph pH (pHv) was also measured simultaneously in the second turn. RESULTS: The application of hydrostatic positive pressure caused a decrease in pHe and EP. Positive perilymphatic pressure caused the endolymph to become acidic pressure-dependently. Application of 3.0% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.

Magnetic resonance imaging features of large endolymphatic sac compartments: audiological and clinical correlates.

OBJECTIVES: (1) To study the prevalence and characteristics of large endolymphatic sac internal compartments on thin-section T2- and T2*-weighted magnetic resonance imaging, and to relate these to other large endolymphatic sac magnetic resonance imaging features, and (2) to correlate the compartment imaging features, endolymphatic sac size and labyrinthine anomalies with the patients' clinical and audiological data. METHOD: Magnetic resonance imaging studies for 38 patients with large endolymphatic sac anomalies were retrospectively reviewed in a tertiary referral centre. Endolymphatic sac compartment presence, morphology and imaging signal were assessed. Endolymphatic sac size and labyrinthine anomalies were also recorded. Endolymphatic sac compartments and other imaging features were correlated with clinical and audiological data. RESULTS: Compartments were present in 57 per cent of the imaged endolymphatic sacs, but their presence alone did not correlate with other imaging features or clinical data. The endolymphatic sac : internal auditory meatus signal ratio was associated with a history of sudden or fluctuating hearing loss. Hearing loss correlated with opercular and extraosseous endolymphatic sac size measurements. A larger midpoint intraosseous endolymphatic sac size was associated with clear fluid loss at cochlear implantation. CONCLUSION: The magnetic resonance imaging characteristics of large endolymphatic sac compartments have been defined. The endolymphatic sac size and distal compartment signal should be recorded, as these provide prognostic information and assist the planning of appropriate interventions.

Rapid elevation of gentamicin levels in the human labyrinth following intravenous administration.

HYPOTHESIS: Adequate quantities of labyrinthine fluid can be sampled from the human labyrinth to perform quantitative analysis of medications. A rapid elevation of intralabyrinthine gentamicin levels after intravenous administration can be measured. A model for the sampling of human inner ear fluid in this manner is described. BACKGROUND: The risk of aminoglycoside ototoxicity has been a long-standing concern. The kinetics of gentamicin diffusion into the inner ear have been extrapolated to humans from various animal models. The validity of extrapolation to humans is unknown. We have developed a new model to measure the uptake of gentamicin in vivo. METHODS: A single intravenous dose of gentamicin (80 mg) was given perioperatively to 13 patients undergoing translabyrinthine acoustic neuroma surgery. The lateral semicircular canal and vestibule were opened and a microsyringe was used to obtain a sample of labyrinthine fluid concomitant with a serum sample. The gentamicin concentration of the labyrinthine fluid and serum was analyzed using a standard chemistry analyzer. RESULTS: After parenteral administration of gentamicin, fluid was obtained from the inner ear of 13 acoustic neuroma patients. Inner ear concentrations were between 1.0 and 3.8 mg/L. Serum gentamicin levels ranged from 1.2 to 10.5 mg/L. CONCLUSIONS: This method allows the sampling of intralabyrinthine fluid in humans. Gentamicin was noted immediately in the labyrinth after intravenous administration. This model may be expanded to measure other compounds given either by intravenous or transtympanic routes.

Intratympanic ciprofloxacin and the human labyrinthine sampling model.

OBJECTIVE: The aim of the study was to investigate the potential absorption of intratympanic ciprofloxacin through the human round window membrane. STUDY DESIGN: A prospective study. METHODS: Ciprofloxacin was instilled into the middle ear of 10 patients undergoing acoustic tumor removal. The lateral semicircular canal and vestibule were subsequently opened and, using a microsyringe, labyrinthine fluid was aspirated. A sample each of serum and cerebrospinal fluid was also drawn. RESULTS: Into each middle ear, 0.5 mL ciprofloxacin (0.3%) was instilled. The time interval between the ciprofloxacin application to the round window membrane and sampling of labyrinthine fluid and plasma ranged from 9 to 120 minutes. There was no measurable ciprofloxacin in the labyrinthine fluid, cerebrospinal fluid, or serum of 10 patients. CONCLUSION: The lack of measurable absorption of intratympanic ciprofloxacin into the inner ear indicates that the chance of ototoxicity when ciprofloxacin is used clinically, even in the presence of a tympanic membrane perforation, is low.

Histologic demonstration of glycosaminoglycans in inner ear fluids.

Hyaluronic acid is a glycosaminoglycan (GAG) which has been demonstrated by biochemical and histochemical methods to be present in inner ear fluids and tissues. However, consistent labeling of hyaluronic acid or other GAGs in inner ear fluid compartments in histologic sections has not been previously reported. Staining and characterization of GAGs in the normal inner ear fluids of humans and guinea pigs are described in this report. It was initially observed that alcian blue produces dense staining of the endolymphatic and perilymphatic fluid compartments in celloidin embedded material. Results obtained with alcian blue were subsequently compared to staining obtained with hematoxylin/eosin and periodic acid/Schiff base. Enzyme digestion was also performed with testicular hyaluronidase (bovine and ovine), streptomyces hyaluronidase, chondroitase ABC, and alpha-amylase. Results of the differential staining and enzyme digestion studies suggest that the substances in inner ear fluids that stain with alcian blue are a combination of chondroitin sulfate-4, -5 and/or -6 and hyaluronic acid.

Importance of type IV collagen, laminin, and heparan sulfate proteoglycan in the regulation of labyrinthine fluid in the rat cochlear duct.

The distribution of major components of the basement membrane, such as type IV collagen, laminin, and heparan sulfate proteoglycan (HSPG), was investigated in the rat cochlear duct. Immunofluorescence demonstrated that type IV collagen, laminin and HSPG were distributed along capillaries in the cochlear duct, including the stria vascularis, spiral ligament, spiral prominence and spiral limbus. Additionally, type IV collagen, laminin and HSPG were found to be distributed from the basement membrane of Reissner's membrane to that of the spiral prominence in a linear pattern. The scala media was surrounded by these basement membrane components, demarcating endolymph from perilymph, along epithelial cells except at the stria vascularis. These findings suggest that type IV collagen, laminin and HSPG create the anatomical separation between endolymph and perilymph, thus indicating that they may be involved in the regulation of fluid transport between the endolymph and perilymph.

[Glycerol electrocochleographic test: role of endolymphatic sac?]. / Test électrocochléographique au glycérol: rôle du sac endolymphatique?.

The administration of a dehydrating agent like glycerol may improve the audiometric thresholds and decrease the summating potential in the electrocochleographic recordings of some Méière's diseases. There are many discussions concerning the endolymphatic sac's rôle in this cases. To clarify this subject we have reviewed the labyrinth's liquids physiopathology, the structural observations in cases of Ménière's diseases, the animals models date. We conclude that the presence of an endolymphatic sac is not necessary for obtaining a positive glycerol test. The clinical meaning of this test is discussed.

Accuracy of an automatic impedance apparatus in a population with secretory otitis media: principles in the evaluation of tympanometrical findings.

INTRODUCTION: The primary demand for a screening procedure for secretory otitis media (SOM) is to identify an objective test with sufficient sensitivity and specificity to meet the needs of the screening program. This study was designed to estimate the value of a portable automatic impedance apparatus to meet these needs. SUBJECTS AND METHODS: Two hundred twenty children with unilateral or bilateral SOM were evaluated in a double-blind, cross-sectional study. All have fulfilled two of the following three criteria for surgical intervention: (1) SOM by physical examination, (2) greater than 20 dB hearing impairment, and/or (3) adenoid symptoms. All ears were evaluated using tympanometry, following which myringotomy was performed. RESULTS: Otomicroscopy showed fluid behind the tympanic membrane in 393 ears. All underwent myringotomy. Thirteen percent (51 ears) were empty. Of the otomicroscopic findings consistent with SOM, 82% had B curves, 6% had C2 curves, 8% had C1 curves, and 4% had A curves. Both C2 and B curves were considered abnormal. Sensitivity of the apparatus is 94.4% and of the specificity is 52.9%. There was no statistical correlation between tympanometrical findings and fluid viscosity. RESULTS: A test intended for screening has to be simple, easy, and quick to perform. Furthermore, the test should have high sensitivity. The automatic impedance apparatus is able to meet these demands; however, the individual results have to be confirmed by another method, eg, otomicroscopy, pure-tone audiometry, and/or manual tympanometry.

Pathophysiology of inner ear fluid imbalance.

Maintenance of homeostasis of inner ear fluids and biochemical integrity of inner ear tissue are essential for proper functioning of the auditory and vestibular end organs. Although various regulatory mechanisms exist in a different portion of the labyrinth, the inner ear is known to respond to systemic challenges. The association of Meniere's syndrome with an imbalance of inner ear fluid homeostasis has been hypothesized for the past century. Among many factors, the effects of hormonal imbalance on inner ear fluid composition and inner ear function have however scarcely been studied. The purpose of this study was to explore the relationship between the autonomic nervous system and inner ear function and possible mechanisms of functional disturbances in an experimental condition. An infusion of supraphysiologic amounts of epinephrine, a stress related hormone, resulted in an elevation of osmolality in serum and perilymph. Furthermore, the infusion of epinephrine resulted in elevation of threshold, prolongation of latency, and depression of amplitude in the compound action potential of the auditory nerve. These findings were most marked at high frequencies. We hypothesized that the epinephrine-induced hearing loss was brought about by an increase in perilymphatic osmolality, as well as by the ionic imbalance caused by the osmotic gradient. Since emotional stress has been implicated as a mechanism of inducing a Meniere's attack, evaluation of the relationship between the autonomic system and cochlear function may contribute to the understanding of possible mechanisms of inner ear dysfunction caused by hormonal imbalances.