Gas exchange function of the middle ear in patients with otitis media with effusion

Gas exchange function through the middle ear mucosa was assessed using nitrous oxide (N₂O) in patients with otitis media with effusion (OME), as well as in normal ears during elective surgery for unrelated disorders. In all normal ears except one (n = 43), an increase in pressure was observed after N₂O inhalation. In 42 of 84 ears with OME, a pressure increase was observed, but not in the remaining 42 ears (50%), indicating that the gas exchange function in these latter ears was impaired. In 21 of the 42 ears showing no middle ear pressure increase following N₂O inhalation, the middle ear pressure was again monitored after myringotomy and aspiration of the effusion A pressure increase was found in 16 ears, indicating that the impairment in gas exchange function in ears with OME may be reversible in most cases. Computed tomography of the mastoid was examined preoperatively in 66 ears, with the presence or absence of a middle ear pressure change well correlated in 57 ears with the presence or absence of mastoid aeration.     

The atelectatic ear

Direct measurements of middle ear pressure were performed in 14 children with recurrent middle ear effusion and deep retraction of the tympanic membrane. In 12 of the 22 ears studied, measurements showed that a high negative pressure in the middle ear space had been induced by sniffing. Results suggest that a combination of closing failure of the Eustachian tube and sniffing is the cause of effusion and progressive retraction of the tympanic membrane in these patients. It is further suggested that cholesteatoma, which was present in three of the patients, was also a result of sniff-induced negative pressure in the middle ear space.     

Mucosal surface area determines the middle ear pressure response following establishment of sniff-induced underpressures

INTRODUCTION: Miura and colleagues presented data that they interpreted as evidencing a pressure-regulating function of the mastoid mucosa. Specifically, they reported different responses after sniff-induced middle ear (ME) underpressure for ears with and without a history of otitis media with effusion (OME). To understand the mechanism underlying that effect, a previously developed mathematical model was adapted to their experiment and used to simulate the expected pressure-time functions under different conditions. METHODS: A simple, two-compartment model of passive, gradient-driven, trans-mucosal gas exchange was used to simulate ME pressure behaviour. Initial conditions for the free parameters of the model were taken from published data for humans and monkeys. Functions relating surface area to volume for geometric representations of the ME were constructed and used as model parameters. The effect of sniffing on ME gas partial pressure was modelled as a fractional reduction proportional to gas representation in the ME. RESULTS: The model accurately simulated the time course and magnitude of the post-sniffing pressure change reported for both normal and abnormal MEs. The post-sniffing pressure increase is driven by sniff-induced blood-ME partial pressure gradients for CO2, O2, and H2O, which cause passive counter-diffusion of those gases. The effect of disease on the rate of pressure increase is attributable to the reduced surface area for exchange caused by underdevelopment of the mastoid in ears with a history of OME. CONCLUSIONS: These results do not support a pressure-regulating role for the mastoid mucosa. Contrary to currently held beliefs, the model simulation suggests that small, not large mastoid volumes buffer ME pressure from rapid change due to trans-mucosal gas transfers.     

Organic change of effusion in the mastoid in otitis media with effusion and its relation to attic retraction

To try to solve the pathogenesis of severe attic retraction viewed from mastoid condition, we examined the residual soft tissue density (RSTD) in the mastoid by computed tomography (CT) in 85 patients (107 ears) with otitis media with effusion (OME) 3 months after tympanostomy tube insertion or later. The incidence of RSTD in the mastoid was significantly higher in OME of adults (52.6%) than in children (24.1%). Ears with severe attic retraction had RSTD significantly more frequently (80%) than those with no or mild attic retraction, and many of the mastoids with severe attic retraction were occupied totally by RSTD. The area of the mastoid (mastoid pneumatization) was significantly smaller, and CT density of the mastoid (sclerotic tendency) was significantly higher in ears with RSTD than in those without. RSTD after tympanostomy tube insertion in the mastoid indicating organic change of effusion was considered one of the important factors relating to the pathogenesis of severe attic retraction.     

Sniff-induced negative pressure--a cause for the development of middle ear diseases?

The significance of "sniffing" causing tubal dysfunction and thus leading to the development of cholesteatoma is discussed. We examined 244 healthy ears (18% sniff-positive), 21 ears with a traumatic perforation of the tympanic membrane (10% sniff-positive), 46 ears with chronic mesotympanic otitis (17% sniff-positive) and 40 ears with cholesteatoma (60% sniff-positive). Two different methods were used: on intact tympanic membranes the pressure chamber impedance method described by Munker-Pedersen (1972), and for perforated tympanic membranes a pressure transducer. Our results show that: (1) "sniffing" can cause negative pressure in the middle ear space; (2) the traditional concept of opening failure is no longer sufficient to explain tubal dysfunction; (3) sniff-induced negative pressure is a further possible cause of tubal dysfunction; (4) sniff-induced negative pressure seems to be an important factor in the development of cholesteatoma.     

上鼓室内陷袋的临床特征分析

目的：探讨上鼓室内陷袋的临床特征。方法：分析92例（118耳）上鼓室内陷袋患者的临床资料、临床表现（常以耳闷胀感、听力下降及耳鸣为主诉）、耳内镜检查及分级、听力学、影像学检查及并发病变。结果：118耳中,TosⅠ～Ⅳ级分别为15耳（12．7％）,48耳（40．7％）,23耳（19．5％）及32耳（27．1％）。耳内镜下可见并发的分泌性中耳炎41耳（34．7％）、中耳膨胀不全16耳（13．6％）、粘连性中耳炎8耳（6．8％）及内陷袋胆脂瘤。纯音测听以传导性聋为主,少数还有以传导性聋为主的混合性聋。因并发中耳疾病及疾病性质的不同,而对听力的影响也不同,且差异也有统计学意义（P〈0．01）。Ⅰ～Ⅲ级各病变组与Ⅳ级病变对听力的影响有统计学意义（P〈0．01）,Ⅰ～Ⅲ级之间的听阈无统计学意义（P〉0．01）,声阻抗以平坦型及负压为主。其中97耳CT及X线摄片结果显示,乳突气化不良程度与对照组有差异（P〈0．01）。结论：上鼓室内陷袋反映中耳负压状态,其发病机制与咽鼓管功能、炎症、乳突气化程度相关;因其存在发展为内陷袋胆脂瘤的潜在危险,故临床上应加强早、中期病变的随访及干预。     

Tympanic membrane atrophy, scarring, atelectasis and attic retraction in persistent, untreated otitis media with effusion and following ventilation tube insertion

Two hundred and twenty two children with persistent bilateral otitis media with effusion (OME) were treated with unilateral ventilation tube insertion and no treatment to the contralateral ear. The tympanic membrane changes in the operated and unoperated ears were compared during a 12 year follow-up. Segmental atrophy resulted from tube insertion whereas minor scarring and thickening of the pars tensa was related to the middle ear condition. Eighty three percent of untreated ears and 85% of those treated with tubes did not develop atelectasis. Sixty percent of untreated ears and 64% of treated ears did not develop attic retraction. Very few cases (1.5 and 2%) in untreated and treated ears, respectively developed severe atelectasis. The overall duration of OME was assessed from the pre-operative history of hearing loss, the 3 month period of pre-operative observation and the post-operative time with effusion. There is a relationship between duration of the disease and development of both atelectasis and attic retraction.     

保留乳突的改良完壁式鼓室成形术的临床疗效观察

目的 探讨局限于上鼓室区病变的慢性化脓性中耳炎、中耳胆脂瘤行上鼓室径路保留乳突的改良完壁式鼓室成形术的长期临床疗效.方法 诊断慢性化脓性中耳炎、中耳胆脂瘤47例(47耳)患者,结合患者专科检查,依据手术方式不同分A、B两组,A组行上鼓室径路保留乳突的改良完壁式鼓室成形术,B组行完壁式乳突切开+鼓室成形术.术后随访5～7...     

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.     

Eustachian tube function following adenoidectomy: an evaluation by sniffing

Recent investigations have demonstrated an association between sniff-induced negative middle ear pressure and otitis media with effusion. This is taken as evidence of Eustachian tube malfunction. Adenoidectomy is frequently performed as part of the surgical management for otitis media with effusion, but whether this affects Eustachian tube function is uncertain. The aim of this study was to investigate the hypothesis that if adenoidectomy improved Eustachian tube function, children who had undergone adenoidectomy would show less tendency to generate a high negative intratympanic pressure by sniffing. Eustachian tube function was studied actively in 40 children with otitis media with effusion. Twenty children, selected at random, underwent adenoidectomy and all 40 had a unilateral grommet inserted. Eighty-five percent of the children could create a negative middle ear pressure by sniffing, but there was no difference in the number of 'sniff + ve' children between the adenoidectomy and control groups (P greater than 0.5), or in the magnitude of the negative pressure induced. It is concluded that a high percentage of children with otitis media with effusion are capable of inducing a negative middle ear pressure by sniffing, but this parameter of Eustachian tube function is not affected by adenoidectomy.     

Clinical studies on attic retraction]

Attic retraction was studied in 327 ears of 264 patients in whom photographs of the tympanic membrane were taken from 1983 to 1989. Attic retraction was investigated clinically on the basis of findings of the tympanic membrane in reference to the photographs and ear X-ray findings, including CT. Attic retraction was also observed in 4.5% of cases without inflammation, but its severity was mild. The incidence of attic retraction in cases of adhesive otitis media was 42.7% in mild adhesive otitis media (adhesive grade I) and 60.8% in severe adhesive otitis media (adhesive grade II), both incidences were significantly higher than the incidence of 23.8% in cases of otitis media with effusion. Thus, the incidence of attic retraction increased as the grade of adhesion became severer. In cases of otitis media with effusion, the incidence was significantly higher in the adult group (32.3%) than in the child group (17.4%). In many of the ears with otitis media with effusion, adhesive grade I and chronic otitis media, the severity of attic retraction was mild. There were more cases of milder retraction in the child group than in the adult group. Attic retraction underwent change with time in 2.8% of cases, and cholesteatoma occurred in 1.8% of cases. No improvement in attic retraction was achieved by insertion of a ventilation tube. Bilateral attic retraction was observed in 56.9% of the child group and 30.2% of the adult group, and the difference was statistically significant. Ear X-ray findings by Schüller's method revealed many ears with poorly developed mastoid cells and poor pneumatization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Direct measurement of middle ear pressure through the eustachian tube

We report a method for measuring middle ear pressure through the eustachian tube. We used a 1-mm-diameter micro-tip catheter pressure transducer (Mikro-tip) and inserted this into the tympanic cavity through the eustachian tube. In preliminary studies, we measured four normal ears, two ears with tubal dysfunction, one ear with a dry perforation and 13 ears with otitis media with effusion (OME). Among those ears with OME, three showed negative middle ear pressure, three slight positive pressure and one normal pressure. These findings suggest that our transtubal method is reliable and useful for measuring middle ear pressure.     

Relationship between middle ear pressure,mucosal lesion,and mastoid pneumatization

Objectives: The inflammatory changes of pneumatic space mucosa are thought to affect the development of pneumatic space and the function of transmucosal gas exchange. So, it is assumed that the mucosal change is deeply involved in the onset and healing process of otitis media with effusion (OME). The objective of this study is to investigate whether the growth of the mastoid cells and the middle ear transmucosal gas exchange function in patients with OME are affected by the histopathologic changes in middle ear mucosa, and whether these two factors are changed by the treatment of OME. Materials and Methods: From 65 children with OME, middle ear mucosal specimens were collected during indwelling of a tympanic tube, and their histopathologic changes were compared with cell growth area measured on radiographic films and with the change in the middle ear total pressure (METP). Results: Suppression of the cell growth area was stronger and the METP stayed lower in cases with a higher degree of mucosal lesion. Significant expansion of pneumatic area was observed after 2 years of tube indwelling, and the peak METP showed a significant increase after 1.5 years. This increase in the METP was caused by diffusion/absorption of CO₂ and O₂ and indicated recovery of the transmucosal gas exchange function. Conclusions: The growth of the mastoid cells and the middle ear transmucosal gas exchange function are closely affected by the subepithelial histopathologic changes in middle ear mucosa, and these two factors recover by the treatment of OME.     

Spread and Fate of Amniotic Fluid Cellular Content in the Middle Ear

In this study, 24 temporal bones with an age range from neonates to 23-month-old infants were serially sectioned and studied for the spread and fate of amniotic fluid cellular content (AFCC) in the middle ear and mastoid. Most children had had either a moderate or massive contamination. AFCC clusters were found to spread to all compartments, with the sites of predilection being the stapes region, the lower lateral attic and the tympanic isthmus. AFCC created an intensive foreign body giant cell reaction and the foreign material practically dissolved in 5 months as a result of the organization process. Tiny remnants of AFCC appeared as late as 15 months after birth. It seems likely that AFCC contamination predisposes the ears to recurring otitis media. The sequalae of the massive granulation tissue development involves obliteration of Prussak's space and its aeration routes, as well as blockage of the tympanic isthmus, leading to extensive disease in the major attic compartments.     

Direct measurement of middle ear pressure through the eustachian tube

Summary We report a method for measuring middle ear pressure through the eustachian tube. We used a 1-mm-diameter micro-tip catheter pressure transducer (Mikro-tip) and inserted this into the tympanic cavity through the eustachian tube. In preliminary studies, we measured four normal ears, two ears with tubal dysfunction, one ear with a dry perforation and 13 ears with otitis media with effusion (OME). Among those ears with OME, three showed negative middle ear pressure, three slight positive pressure and one normal pressure. These findings suggest that our transtubal method is reliable and useful for measuring middle ear pressure.     

Middle ear pressures in eustachian tube malfunction: manometric studies

We made direct measurements of the difference in pressure between the middle ear and the ambient atmosphere in 300 ears affected with chronic adhesive otitis media (CAOM), serous otitis media (SOM), and similar disorders of the ear caused by eustachian tube malfunction. We utilized a narrow bore, open U-tube manometer made of No. 205 polyethylene tubing which was connected to a 20 or 22 gauge spinal needle. The needle was passed through the intact tympanic membrane and the displacement of the column of 95 percent alcohol in the manometer was noted and recorded. Our results showed that in 101 ears with CAOM, the average negative pressure difference between the middle ear and the ambient atmosphere was 9 mm 95 percent alcohol, equivalent to 7 mm of H₂O. In 136 ears with SOM, the average negative middle ear pressure was 8 mm 95 percent alcohol, equivalent to 6.5 mm H₂O. In 80 of the 300 diseased ears we tested, the middle and ambient atmospheric pressures were equal. Direct readings of the middle ear pressure tell us the status of the middle ear ventilation at the moment of the measurement.     

Middle Ear Effusions and the Nitrous Oxide Myth

Myringotomies were performed on 75 ears suspected of having chronic or recurrent otitis media with effusion. Preanesthesia and intraoperative tympanograms with halothane, nitrous oxide, and oxygen anesthesia were compared for possible changes in middle ear pressure due to anesthesia. In addition, preanesthesia tympanograms were compared with tympanograms taken 2 weeks before hospital outpatient surgery. Tympanograms of 11 ears were found to shift from a flat type recorded at the office visit to normal range at pre and postinduction anesthesia. Middle ear fluid was not present in any of these 11 ears. The remaining 64 ears were broken down into three abnormal tympanogram configurations; flat, roll-over, and peaked negative pressure types. Comparing the tympanograms done in the office, preanesthesia and intraoperatively, only one of the 64 ears showed a change after induction of anesthesia. Three of the 64 ears revealed an unpredictable result with negative myringotomies. These results tend to support tympanometry as a means in predicting myringotomy findings, and also refute the contention that short-term nitrous oxide anesthesia changes the middle ear effusion during myringotomy.     

PERSISTENCE OF MIDDLE EAR DYSFUNCTION AFTER RECURRENT ACUTE OTITIS MEDIA

The presence of otitis media with effusion (OME) and high negative pressure (-200 to -400 mm H₂O)₃ were investigated in follow-up of a randomized double-blind placebo-blind placebo-controlled trial on the efficacyu of amoxicilin/clavulanic acid in the treatment of acute otitis media. All children in this study were recruited from a general practice population. Tympanometry results 1 month from the start of an episode of acute otitis media were taken as outcome criteria. Bilateral middle ear dysfunction was defined as bilateral OME, unilateral OME and contralateral or bilateral high negative pressure. Bilateral middle ear dyusfunction was present in 47.9% of the patients. Of all teh investigated factors of possible influence (age, sex, season, laterality of acute otitis media, therapy, and clinical course of acute otitis media), only season showed a statistically significant influence on the persistence of OME/high negative pressure (P = 0.001). Bilateral middle ear dysfunction was shown to be of prognostic value for the risk of a recurrence of acute otitis media (odds ratio 3.75). shown to be of prognostic value for the risk of a recurence of acute otitis media (odds ratio 3.75).     

Adenoidectomy With Laser or Incisional Myringotomy for Otitis Media With Effusion

Objective To compare the effectiveness of CO₂ laser myringotomy to incisional myringotomy at the time of adenoidectomy for refractory otitis media with effusion (OME). Study Design Controlled retrospective consecutive case series. Methods All children undergoing myringotomy and adenoidectomy for OME in the spring of 1999 had 1.7‐mm‐diameter perforations created in their tympanic membranes using a CO₂ laser and conventional microslad. Their ears were evaluated at first postoperative visit (mean, 16.65 days after surgery) by a validated otoscopist to determine the presence or absence of perforations and middle ear effusions. These patients were compared with historical controls comprising all children undergoing incisional myringotomy and adenoidectomy in 1998. A χ² analysis was performed to compare the results of these two myringotomy techniques. Results Twenty‐three children (39 ears) underwent laser myringotomy and adenoidectomy in 1999, compared with 26 children (48 ears) who underwent incisional myringotomy and adenoidectomy in 1998. In the laser myringotomy group, 8 of the 39 ears had a persistent opening at first follow‐up; 4 of the 39 ears showed evidence of effusion. In the incisional myringotomy group, all 48 ears had healed; 7 of these ears showed evidence of effusion. Conclusion Myringotomies created using the CO₂ laser are more likely to be patent at first postoperative visit than those made with incisional technique (P < .01). However, this prolonged middle ear ventilation does not significantly decrease the prevalence of effusion (P > .1).     

Assessment of complications of the condition and of the treatment of otitis media with effusion

Persistent otitis media with effusion (OME) may cause long-term changes of the tympanic membrane and middle ear, resulting in some degree of hearing loss. One of the traditional aims of treatment with ventilation tubes is to prevent these complications from developing. Ventilation tubes themselves, however, are also known to induce changes of the tympanic membrane. Several recent studies have addressed the questions: what are the effects of the disease, and what are the result of its treatment? The object of this study was to present the state of the art, by literature review, regarding structural and functional complications of OME and treatment with ventilation tubes. In both observational and experimental studies tympanosclerosis is reported to occur in 39-65% of ears treated with ventilation tubes as opposed to 0-10% of untreated ears. For segmental atrophy these percentages are 16-73 and 5-31, respectively. Regarding the prevalence of atelectasis and attic retraction, the difference between ventilated and untreated ears is less: 10-37% as opposed to 1-20% for atelectasis, and 10-52% as opposed to 29-40% for attic retraction. The average hearing loss associated with these tympanic membrane abnormalities is less than 5 dB. Although ventilation tubes have proven very effective in improving hearing in the short term, they have not proven effective in preventing long-term changes of the tympanic membrane related to OME, nor in keeping some degree of hearing loss from developing.