Hirokazu Kawano

Correlation between MRI Findings and Second-Look Operation in Cholesteatoma Surgery

Two-staged intact canal wall tympanoplasty is a common operation for treatment of middle ear cholesteatoma. MRI provides better tissue differentiation of the middle ear and/or mastoid, which often become occupied with soft density tissue after the first operation. If MRI was able to detect the presence of a recurrent or residual cholesteatoma with sufficient sensitivity and specificity, this may facilitate a decrease in the number of second-look procedures. This study compared MRI findings to surgical findings at second-look surgery and calculated the correlation rates between the two sets of findings. Thirty ears having undergone intact canal wall tympanoplasty for cholesteatoma at the initial operation were examined by MRI prior to the second look. Otoscopic findings of the tympanic membrane were nonsuspect in all cases. The true positive rate was 11/30 (37%) and the true negative rate was 10/30 (33%), leading to a radiosurgical correlation of 70%, whereas the false positive rate was 6/30 (20%) and the false negative rate was 3/30 (10%). This indicates that 30% of the MRI findings were incorrect. Therefore, at the present time, MRI does not appear as a likely replacement for second-look surgery in cases of intact canal wall tympanoplasty.

Identification of MUC5B mucin gene in human middle ear with chronic otitis media.

Objectives To identify the mucin gene and its expressing cells in the middle ear mucosa with chronic otitis media (COM), and to study the correlation between infiltration of inflammatory cells in the submucosa and expression of the mucin gene in the mucosal epithelium with COM.

Expression of Mucins in Mucoid Otitis Media

A hallmark of mucoid otitis media (MOM, i.e., chronic otitis media with mucoid effusion) is mucus accumulation in the middle ear cavity, a condition that impairs transduction of sounds in the ear and causes hearing loss. The mucin identities of mucus and the underlying mechanism for the production of mucins in MOM are poorly understood. In this study, we demonstrated that the MUC5B and MUC4 were major mucins in MOM that formed distinct treelike polymers (mucus strands). The MUC5B and MUC4 mRNAs in the middle ear mucosa with MOM were up regulated 5-fold and 6-fold, compared with the controls. This upregulation was accompanied by the extensive proliferation of the MUC5B- and MUC4-producing cells in the middle ear epithelium. Further study indicated that the mucin hyperproduction was significantly linked to CD4+ and CD8+ T cells and/or CD68+ monocyte macrophages. It suggests that MUC5B and MUC4 expression may be regulated by the products of these cells.

Petrous high jugular bulb: a histological study.

PURPOSE A high jugular bulb (JB) is thought to affect structures of the inner ear and possibly cause symptoms there, but clear histological findings of an anatomical relationship between a high JB and the inner ear have not yet been described. MATERIALS AND METHODS We surveyed horizontal sections of 1,591 temporal bones from the collection of the Otopathology Laboratory at the University of Minnesota in Minneapolis, Minnesota, defining a high JB as a JB extending above the inferior margin of the basal cochlear turn. RESULTS In 65 specimens (16%), we found a high JB with its vascular wall obviously thinner than that of a low JB. Bony resorption was occasionally observed around high JBs. Sixteen specimens showed a bony deshiscence between the JB and the endolymphatic sac. Clinical charts showed no obvious symptoms associated with a high JB. CONCLUSIONS Our findings suggest that the JB may have potential to expand upward postnatally. Although our study confirmed occasional bony dehiscence between the JB and the endolymphatic sac, JBs with this involvement may have only a minor effect on function in the inner ear.

Induction of mucous cell metaplasia by tumor necrosis factor alpha in rat middle ear: The pathological basis for mucin hyperproduction in mucoid otitis media

Mucoid otitis media (MOM), one of the leading causes of acquired hearing loss in children, is characterized by mucous cell hyperplasia in the middle ear cleft associated with mucin accumulation in the middle ear cavity. The factors that stimulate mucous cell metaplasia-hyperplasia and mucin hyperproduction are poorly understood. Recent studies demonstrated that tumor necrosis factor a (TNF-α), present in human middle ear effusion, stimulated mucin production in vitro and up-regulated mucin gene expression in vivo. These findings suggest that TNF-α is important in the development of mucous cell metaplasia-hyperplasia. This study demonstrated that inoculation of TNF-α into the middle ear cavity followed by eustachian tube obstruction stimulated mucous cell metaplasia-hyperplasia in the middle ear cleft, accompanied by abundant mucin or mucin-like glycoproteins in the middle ear effusion — a phenotype of MOM in humans. This finding suggests that TNF-α plays a key role in the pathogenesis of MOM through induction of mucous cell metaplasia-hyperplasia and mucin production.

Incidence of External Auditory Canal Exostoses in Competitive Surfers in Japan

Objective. The objective of this study was to demonstrate the prevalence and severity of external auditory canal exostoses in a population of competitive surfers in Japan. The authors used a “surfing index,” the product of the period (years) as an active surfer and the frequency (number of surfing days per week), to predict external auditory exostoses formation. Study design. Cross-sectional study. Setting. A total of 5 surfing competitions that were held in Miyazaki, Japan. Materials and Methods. The ear canals of 373 surfers with an average age of 33.1 years (range, 11-80 years) were examined with an otoscope. The severity of exostosis was classified into 4 groups, ranging from grade 0 to 3, according to otoscopic findings. Subjects also completed a questionnaire detailing their surfing habits. Results. There was a 59.8% overall prevalence of exostoses in 373 surfers. The incidences of grade 1, 2, and 3 exostoses were 118 (31.6%), 71 (19.0%), and 34 (9.1%), respectively. The prevalences of grade 2 and 3 exostoses were higher in surfers with a surfing index of more than 20 (P < .0001). Conclusions. The authors determined that a positive association exists between the surfing index and the severity of exostoses. The findings suggest that it is possible to assume the likelihood of exostosis formation from the surfing index, and this may be of help to spread awareness of exostosis among surfers.

Improved RNA Analysis for Immediate Autopsy of Temporal Bone Soft Tissues

RNA analysis is essential for understanding biological activities of a cell or tissue. Unfortunately, retrieval of RNA from existing archives of human temporal bones has proven extremely difficult due to degradation of RNA molecules. The major factors that contribute to degradation of RNA in specimens from autopsied temporal bones are tissue autolysis due to time elapsed before autopsy, and technical problems in processing the bones after harvest. We therefore focused on improving the survival of RNA in human temporal bones by shortening the time to autopsy and through modification of the processing technique by removing targeted tissues directly from the temporal bones and by avoiding time-consuming decalcification and celloidin-embedding. Eight temporal bones collected at immediate autopsies were used in this study. Representative mRNAs, ranging from high (MUC5B, physically unstable) to low (beta-actin, physically stable) molecular weights, and from abundant (MUC5B) to non-abundant (MUC1) RNA, were studied by in situ hybridization, Northern blot technique, or both. Using this modified protocol in autopsies performed up to 6 h after death, the existence of mRNAs was demonstrated in all bones studied. This improved method demonstrates the feasibility of the use of autopsied temporal bone tissues for RNA analysis.

Expression of pituitary adenylate cyclase-activating polypeptide mRNA in the cochlea of rats.

Expression of mRNA for pituitary adenylate cyclase-activating polypeptide (PACAP) was detected in the cochlea of rats using a reverse transcription-polymerase chain reaction and in situ hybridization. Examination of in situ hybridization demonstrated that cells in the spiral ganglion, and marginal cells in the stria vascularis expressed mRNA for PACAP. These findings suggest that PACAP may play an important role in regulating cochlear functions.

Expression and immunohistochemical localization of adrenomedullin in the mouse cochlea.

Adrenomedullin (AM) is a novel hypotensive and vasodilator peptide. It has been shown that AM is biosynthesized in various organs and cells and is suggested to play multiple roles including electrolyte homeostasis and body fluid control. The present study describes for the first time the presence of mRNA for AM and AM-like immunoreactivity in the cochlea. A reverse transcription-polymerase chain reaction (RT-PCR) performed with gene-specific AM primer on total RNA extracted from mouse cochlea revealed a PCR product of the expected size. Immunohistochemical examination showed positive immunostaining in vascular smooth muscle cells of the modiolar arterioles and in the stria vascularis of the cochlea. These results suggest that AM may play a role in the regulation not only of cochlear hemodynamics but also of cochlear fluid dynamics.

Membrane current possessing the properties of a mechano-electric transducer current in inner hair cells of guinea-pig cochlea.

We measured the membrane current possessing the properties of a mechano-electric transducer current in isolated inner hair cells of guinea-pig cochlea. In a free-standing hair bundle, depolarization to +80 mV evoked a stable outward current attributable to the opening of transducer channels, and repolarization to -80 mV evoked a transient inward current indicating adaptation. The time constant of adaptation increased as the membrane potential depolarized. Dihydrostreptomycin diminished both the outward and inward currents.