Nitric Oxide: A Mediator of Endotoxin-Induced Middle Ear Effusions

Using a rat model, the authors investigated the role of nitric oxide (NO) in endotoxin-induced middle ear effusion (MEE). After the eustachian tube was obstructed, the middle ear was transtympanically injected with 35μL of either 1 mg/mL lipopolysaccharide (LPS) or LPS and 1 mmol/L N-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NO synthase. Over the next 6 hours, the fluid within the middle ear was collected every 2 hours, and the quantity of albumin in the fluid, an index of vascular leakage, was determined using enzyme-linked immunosorbent assay. L-NAME significantly reduced LPS-induced vascular extravasation into the middle ear. Inoculation of the ear with L-arginine, the substrate for NO synthase, reversed the effects of L-NAME. These results indicate that NO is a mediator of LPS-induced MEE. Therefore, inhibition of NO synthase may represent a novel approach to the treatment of otitis media with effusion.     

Middle Ear Pressure Variation: Effect of Nitrous Oxide

Previous studies examining middle ear pressure changes due to inhalant anesthesia, including nitrous oxide, have cited equivocal results. An investigation was performed to closely monitor changes in middle ear pressure during middle ear surgery. Baseline tympanometry was performed before anesthesia, and middle ear pressure was then documented in 1-min time intervals. A total of 97 subjects were studied; 51 received nitrous oxide and halothane, and 46 received halothane alone. Results indicate that nitrous oxide causes significantly greater pressure fluctuations than halothane alone. There were no effects for time of surgery, type of fluid, or baseline. Pressure fluctuation was attributed to eustachian tube function. Case studies are presented to demonstrate subject variability, and suggestions for validation study procedures are presented.     

In Vivo Optical Characterization of Middle Ear Effusions and Biofilms During Otitis Media

Journal of the Association for Research in Otolaryngology - Otitis media (OM), a common ear infection, is characterized by the presence of an accumulated middle ear effusion (MEE) in a normally...     

General Anesthesia With and Without Nitrous Oxide (N2O) and the Weight of Middle Ear Effusion in Children Undergoing Adenoidectomy and Tympanostomy

This study was designed to explore the effect of nitrous oxide (N₂O) on the amount of middle ear effusion. Seventy-six children referred for adenoidectomy or tympanostomy tube placement were divided into two groups in the basis of the method of anesthesia. One group of 39 children was ventilated with a mixture of 30% oxygen and 70% nitrous oxide, while the other group of 37 patients was ventilated with a mixture of oxygen and air. The amounts of middle ear effusion obtained in myringotomy were weighed and compared between these groups. Preoperative and perioperative tympanograms were performed. Ventilation with nitrous oxide caused a distinct rise in middle ear pressure. The amount of the middle ear effusion, however, remained the same in the two groups. It is concluded that the operating surgeon can rely on the myringotomy finding even when nitrous oxide anesthesia is used.     

Heme Oxygenase and Nitric Oxide Synthase in Human Middle Ear Epithelium Indicates Local Carbon Monoxide and Nitric Oxide Production

The gas mixture of the middle ear differs from that of the atmosphere, a fact that has been attributed to gas exchange across the middle ear mucosa. Several diseases of the middle ear seem to be related to impaired ventilation together with conjunctional changes in pressure and gas composition. Carbon monoxide (CO) and nitric oxide (NO) have recently been shown to be endogenously produced in the human lung as well as in the nasal airways. The production of CO and NO is enzymatically regulated by heme oxygenase (HO) and NO synthase (NOS), respectively. These enzymes display isoforms that are both constitutively expressed [HO-2, endothelial NOS (eNOS), neuronal NOS (nNOS)] and inducible [HO-1, inducible NOS (iNOS)] following different types of stimulation. The present study was designed to investigate the presence of HO-1, HO-2 and eNOS in the middle ear epithelium, using immunocytochemistry. Specimens from human middle ear mucosa obtained at autopsy and during surgery revealed HO-1-, HO-2- and eNOS-like immunoreactivity, indicating the possibility of local CO and NO production in the middle ear. If this assumption is true, it may affect our understanding of middle ear physiology and give new insights into the mechanisms behind middle ear pathology.     

Compositional Differences Between Bilateral Middle Ear Effusions in Otitis Media With Effusion: Evidence for a Different Etiology?

The aim of this study was to clarify the site of primary pathology in otitis media with effusion. Effusions were collected from 64 children with bilateral effusions at the time of myringotomy. The rheological properties and biochemical compositions of effusions were measured for 23 pairs of effusions, and the levels of the inflammatory mediators TNFα, IL-1β, and IL-8 were measured in 41 pairs using specific enzyme-linked immunosorbent assays(ELISAs). Measurements from paired ears were compared using analysis of variance (ANOVA) tests and significant differences were found for reduced specific viscosity, mucin content, protein content, and levels of IL-8. The results demonstrate that the two ears have different immunological processes or rates of processes which might explain the significantly different rheological properties of effusions. This suggests that each ear undergoes pathological changes independently and has implications for using the opposite ear as a control in clinical trials.     

中耳力学研究与耳微创外科技术

中耳力学研究一直是鼓室成形术的热点。从声学水平认识中耳传声机制是耳显微外科技术提高听力的基础。耳微创外科技术理念引导下的耳显微外科技术结合中耳力学研究理论必将推动鼓室成形技术发展,进而提高鼓室成形后听力效果。     

Long-Term Middle Ear Ventilation

Successful long-term middle ear ventilation was established in 12 patients with chronic eustachian tube hypofunction that had failed to respond to repeated myringotomy and tympanotomy tube insertions by conventional techniques. The 12 patients (13 ears) had insertion of an untrimmed large flange “Per-Lee” type tube through a posterior-inferior tympanomeatal flap approach. The flange extended under the long process of the malleus, and into the hypotympanum and middle ear opening of the eustachian tube. The stem of the tube was brought out through the inferior central pars tensa. All tubes have remained in place for more than three years without serious complications providing adequate middle ear ventilation and preventing adherence of the tympanic membrane to the promontory.     

Middle Ear Promontory Osteoma

Osteomas are benign lesions of the lamellar bone that within the temporal region are common in the external ear canal. Osteomas of the middle ear are extremely rare and until now there are only 14 reported cases. They usually present with conductive hearing loss while others are asymptomatic and diagnosed incidentally.     

Leiomyosarcoma of the Middle Ear and Temporal Bone

Leiomyosarcoma is a malignant tumor of smooth muscle cells that is exceedingly rare in the middle ear and temporal bone. Wide surgical resection is treatment of choice and adjuvant treatment has not proven to be of benefit. This is a report on a patient with otorrhea and rapidly growing mass on postauricualr area. A tumor that was mainly located in the middle ear and temporal bone was surgically removed and proved to be a leiomyosarcoma. The optimal surgical technique and other treatment strategy are discussed.     

Pathogenesis of Middle Ear Adhesions

Middle ear adhesions are well-known to the ear surgeon, although data on etiology, pathogenesis, and significance are lacking in current literature. This study on experimental acute otitis media presents histopathological data on these aspects. Pneumococci were inoculated in the right middle ear bulla of 25 rats; the left ear served as control. At days 4, 8, 16, 90, and 180, respectively, 5 rats were decapitated, and the bullae were removed, opened, and stained with periodic acid-Schiff (PAS)/alcian blue. The entire middle ear mucosae were dissected from the bone, embedded as whole mounts in colophonium chambers, and examined by light microscopy. Representative parts of the mucosae were sectioned and examined in the same way. All inoculated ears from day 8 and later (20 in total), contained mucosal adhesions of various sizes, shapes, and locations. None were found in control ears. The site of predilection for the development of adhesions was the hypotympanum, followed by the anterior epitympanum, the attic, the drum, the interossicular spaces, and the tubal orifice. Based on present histopathological findings, we conclude that the middle ear adhesion is a pathological phenomenon caused by infection, and we propose a six-stage hypothesis of pathogenesis: 1. Localized epithelial rupture; 2. Prolapse of subepithelial tissue; 3. Epithelialization of the prolapse, resulting in a polypous/fold-like prominence; 4. Growth and elongation of the prominence; 5. Fusion of the end/tip of the prominence with another part of the mucosa; 6. Formation of an adhesion.     

Influence of the Gas Exchange Function Through the Middle Ear Mucosa on the Development of Sniff-Induced Middle Ear Diseases

To investigate the influence of gas exchange function through the middle ear mucosa on the development of sniff-induced middle ear diseases, the authors examined the mastoid pneumatization among patients with sniffing habit using computed tomography, and also examined the change of negative middle ear pressure induced by sniffing using tympanogram. In 20 ears with cholesteatoma or adhesive otitis media, the areas of mastoid cavity measured at the level of the lateral semicircular canal were significantly smaller than those in 26 ears with otitis media with effusion (OME) or attic retraction and in eight normal ears with sniffing habit (P < .01 and P < .0001, respectively). In 26 ears with OME or attic retraction, the areas of mastoid cavity were significantly smaller than those in eight normal ears with sniffing habit (P < .0001). By contrast, in the four ears with sniff-induced middle ear disease, the recovery of negative middle ear pressure in 5 minutes without swallowing was less than 10 mm H₂O, whereas in all seven ears with normal eardrum, negative middle ear pressure recovered by more than 20 mm H₂O in 5 minutes. These findings suggested that impairment of gas exchange function through the middle ear mucosa, as well as eustachian tube dysfunction, might be closely related to the development of sniff-induced middle ear diseases.     

Finite-Element Modelling of the Acoustic Input Admittance of the Newborn Ear Canal and Middle Ear

Admittance measurement is a promising tool for evaluating the status of the middle ear in newborns. However, the newborn ear is anatomically very different from the adult one, and the acoustic input admittance is different than in adults. To aid in understanding the differences, a finite-element model of the newborn ear canal and middle ear was developed and its behaviour was studied for frequencies up to 2000 Hz. Material properties were taken from previous measurements and estimates. The simulation results were within the range of clinical admittance measurements made in newborns. Sensitivity analyses of the material properties show that in the canal model, the maximum admittance and the frequency at which that maximum admittance occurs are affected mainly by the stiffness parameter; in the middle-ear model, the damping is as important as the stiffness in influencing the maximum admittance magnitude but its effect on the corresponding frequency is negligible. Scaling up the geometries increases the admittance magnitude and shifts the resonances to lower frequencies. The results suggest that admittance measurements can provide more information about the condition of the middle ear when made at multiple frequencies around its resonance.     

Epidemiology and Aetiology of Middle Ear Cholesteatoma

A total of 500 patients with cholesteatoma diagnosed and operated during 1982-91 in the region of Tampere University Hospital and Mikkeli Central Hospital in Finland were analysed retrospectively. The mean annual incidence was 9.2 per 100,000 inhabitants (range 3.7-13.9) and during the study period the annual incidence decreased significantly. The incidence was higher among males under the age of 50 years. There was no accumulation of cholesteatoma diseases in lower social groups. The majority (72.4%) of cholesteatoma patients had suffered from otitis media episodes. Tympanostomy was carried out in 10.2% and adenoidectomy or adenotonsillectomy in 15.9% of all cholesteatoma ears prior to cholesteatoma surgery. Cholesteatoma behind an intact tympanic membrane with no history of otitis media was verified in 0.6% of patients and in cleft palate patients in 8%. In this study, 13.2% of patients had ear trauma or ear operation in anamnes.