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Biomedical subjects

Y B Choo

Publications and source records attributed to Y B Choo.

8 recordsLinked to original sources
PubMed1987

The permeability of the round window membrane during otitis media.

Studies of the permeability of the round window membrane (RWM) during otitis media are important because toxins and cellular components that occur in otitis media as well as pharmacologic agents used in treating the disease have the potential to cross the RWM and pass into the inner ear. Twenty-five cats were evaluated electron microscopically as to the passage of a tracer, horseradish peroxidase, through normal RWMs and RWMs three days, one week, and two weeks following eustachian tube obstruction. Passage at three days following obstruction was similar to passage through the normal RWM. Following one to two weeks of obstruction, the permeability of the membrane was drastically reduced. The reduction in permeability was probably due to the presence of residual effusion overlying the membrane, the presence of granulation tissue within the niche, and a thickening of the RWM.

Animals↗
PubMed1984

The human round window membrane. An electron microscopic study.

The normal adult human round window membrane was examined by transmission electron microscopy. The membrane consists of the following three layers: (1) an outer squamous epithelial layer with an underlying basement membrane; (2) a middle fibrous layer containing collagen, elastin, fibrocytes, vessels, and nerves; and (3) an inner layer of mesothelial cells. Mucosal membrane veils that cover the round window membrane, forming "false" round window membranes, are also described. These membranes are also three layered, including (1) an outer epithelial layer with an underlying basement membrane, (2) a middle fibrous layer containing collagen, elastin, fibrocytes, vessels, and nerves, and (3) an inner epithelial layer with an underlying basement membrane. Ultrastructural differences between these two structures are discussed.

Aged↗
PubMed1984

Microscopic characteristics of round window problems in otology.

Round window membrane ruptures and perilymph leakage can present the complication or concomitant of sudden deafness and barotrauma. Pathological involvement of the round window membrane can occur in many otological diseases such as otosclerosis, otitis media, tumors, etc. Microscopic manipulations might result in an inadvertent round window membrane lesion and cochlear deafness. In recent years purposeful surgical lesions, including procedures for vertigo and cochlear implant surgery, are being made in the round window membrane. Examples of pathology involving the round window in human temporal bones are described. To understand better the clinical features of early round window rupture in humans,, controlled punctuate lesions were made in 36 chinchilla ears and studied sequentially. Round window membrane healing occurred as early as 3 days post-lesion, and was complete in all ears but 1 of the combined 7, 9 and 11-day group. Healing occurred primarily as a result of middle ear epithelial ingrowth and mesothelial cell reaction in the adjacent perilymphatic space of the scala tympani. These cellular events are described and discussed from an histological and clinical point of view.

Adult↗
PubMedDate not supplied

The round window membrane: otological observations.

The membrane of the round window serves as a barrier between the middle and inner ear and has a well-established role in cochlear physiology. It is important in many otological conditions: otitis media, otosclerosis, trauma, sequelae to drugs reaching the middle ear, tumors, congenital dysplasia, sudden deafness. We here describe the first electron microscopic findings in round window membranes from adult humans, and various conditions in reference to these findings. Since surgical lesions are made in this membrane during cochlear implantation, and by some otologists in treating vertigo, preliminary findings of a lesioning experiment in animals are presented. Interestingly, early healing resulted from a mesothelial cellular reaction in the adjacent scala tympani, with formation of clots, while in the middle ear the epithelial cellular layer sealed the edges of the perforation, leading to formation of an indentation ("pocket"). Subsequently, the middle layer of the membrane contributed to healing.

Adult↗
PubMedDate not supplied

Sensorineural hearing loss in otitis media.

Additional evidence is presented to support the hypothesis that both acute purulent otitis media (POM) and chronic suppurative otitis media (COM) can cause high frequency sensorineural hearing loss. In selected patients and in animals (chinchillas) in a pilot study using electrophysiological methods, both temporary threshold shifts and permanent threshold shifts of basal cochlear turn involvement were demonstrated in POM. Data of cochlear involvement in 475 ears with bilateral COM, 607 ears with unilateral COM, and 607 ears serving as controls were obtained from six centers in five countries. In group 1 (15 dB or greater), 43% of ears with unilateral COM and 42% of ears with bilateral COM showed losses, for a combined odds ratio eight times that in controls. In group 2 (30 dB or greater), 16% of ears with unilateral COM and 17% of ears with bilateral COM demonstrated, respectively, seven and ten times that in controls. These statistically significant findings influence clinical considerations.

Acoustic Impedance Tests↗