Myringotomy: A Prerequisite for the Development of Myringosclerosis?

Streptococcus pneumoniae was inoculated into the left middle-ear cavity in two groups of rats, resulting in purulent otitis media. After 3 days, one group of infected animals and a third group of noninfected animals were subjected to left-sided myringotomy. The tympanic membranes were examined both otomicroscopically and histologically 1 and 3 months later. On otomicroscopic examination the noninfected myringotomized animals had developed extensive myringosclerotic lesions, whereas only minimal sclerotic deposits were noted in the myringotomized animals with acute otitis media (AOM). On histologic examination both the noninfected myringotomized animals and the myringotomized animals with AOM were similar in the frequency and extension of sclerotic lesions in the tympanic membrane. The nonmyringotomized rats with AOM were free of sclerotic lesions, except for minor changes found in one animal.     

Myringotomy with and without tympanostomy tubes for chronic otitis media with effusion

We studied 109 children with otitis media with effusion of 2 months' duration or longer that was unresponsive to medical management. Eighty-six subjects who had neither "significant" hearing loss nor defined symptoms were randomly assigned to receive myringotomy, myringotomy with tympanostomy tube insertion, or no surgery, and 23 subjects with significant hearing loss, defined symptoms, or both were randomly assigned to receive either myringotomy or myringotomy with tube insertion. Myringotomy with tube insertion provided more disease-free time and better hearing than either myringotomy alone or no surgery; however, some subjects who underwent myringotomy with tube insertion developed otorrhea or persistent perforation of the tympanic membrane. Myringotomy offered no advantage over no surgery regarding percent of time with middle-ear effusion, number of acute otitis media episodes, and number of subsequent surgical procedures. These results may not properly be extrapolated to less severely affected children.     

Labeling of the glucocorticoid receptor and Na,K-ATPase in a rat otitis media model

HYPOTHESIS: Glucocorticoid hormones exert an influence on the inflammatory response of the middle ear during acute otitis media. Rats with experimentally induced purulent otitis media were given either glucocorticoid hormones in excess or a glucocorticoid hormone blocker that deprived the animals of the hormone. BACKGROUND: Acute otitis media is a common inflammatory disease among children. Streptococcus pneumoniae is the most usual causative agent. The standard treatment today is phenoxymethylpenicillin. The role of glucocorticoid hormones in inflammatory reactions in the middle ear has been widely debated. METHODS: In an otitis media model, a suspension of pneumococci was inoculated into the bulla of the rat, after the animals were pretreated with either a dose of corticosteroid hormones or the glucocorticoid receptor blocking agent RU 486. Rats with induction of otitis media only, but no pretreatment, were used as control subjects, as were the left control-operated ears of all rats. The inflammatory response in the inner ear and in the middle ear was evaluated. The presence of glucocorticoid receptors and the enzyme Na,K-ATPase was investigated with immunohistochemistry. RESULTS: The inflammatory response in the animals with untreated otitis media and in the group with otitis media in rats pretreated with the receptor blocker was much more extensive than in the group of animals pretreated with corticosteroids. In the corticosteroid-treated group, the tympanic membrane and the mucous membrane of the middle ear were less edematous, but the middle ear cavity contained more pus. Only a few lymphocytes were found in the inner ears of these rats. When the inner ear was labeled with antibodies against glucocorticoid receptors, there seemed to be no difference between the labeling patterns in the three groups. This was also the case for antibody labeling against Na,K-ATPase. CONCLUSION: The present results indicate that the reaction in the middle ear mucous membrane is more pronounced in rats that had been pretreated with the hormone receptor blocking drug. An increase of corticosteroid hormone levels during the inflammatory process seem to diminish the reaction in the tympanic membrane and the middle ear mucosa. Neither the hormone receptor blocking drug nor the steroid hormones change the content of glucocorticoid receptors and Na,K-ATPase in the inner ear in the otitis media rat model.     

Laser myringotomy

The aim of the study was assessment of the qualities of laser-assisted myringotomy (LAM) as a treatment for acute and secretory otitis media. Laser-assisted myringotomy was performed on 65 children (113 ears) mean age 6.2 years diagnosed with secretory otitis media (80%), recurrent secretory otitis media (11%) and acute otitis media (9%). Myringotomy was performed under general anesthesia using the OtoLAM device (ESC/Sharplan, Israel). In 64 ears pressure equalisation tubes were inserted after fenestration of the tympanic membrane with laser. Adenoidectomy alone or with tonsillectomy was performed at the same time in 51 cases. Laser tympanostomies remained patent for 7-32 days. All tympanostomies healed with no noticeable scarring. LAM appears to be a safe, and easy to performed, alternative technique in the treatment of otitis media.     

Myringotomy in the treatment of acute otitis media in children.

The treatment of acute otitis media was studied in 158 children. All children (mean age 4 years) received penicillin orally 80 000--100 000 IU per day for 10 days. Myringotomy was performed on 68 children at the time of the diagnosis. The other 90 children were treated with penicillin and ear drops. The bacteriological findings from the nasopharynx at the time of diagnosis were equivalent in both groups. After 2 weeks, 42% of the children without myringotomy and 71% of the children with myringotomy were cured. The children who were not cured were treated with amoxicillin for 10 days. Four weeks after diagnosis 71% and 90% of the children respectively were cured. The differences between the two groups are significant. The observations indicate that myringotomy clearly accelerates the recovery from acute otitis media.     

Calcium deposition and expression of bone modelling markers in the tympanic membrane following acute otitis media

BACKGROUND AND OBJECTIVES: In accordance with clinical findings, myringosclerosis develops after otitis media (OM) and paracentesis in an experimental setting. The pathogenesis of this phenomenon of calcification is poorly understood. As the calcification process and the sclerotic plaques of the drum mimics features of bone tissue, this study explores tympanic membrane calcium deposition in association with the expression of three bone modelling markers: osteopontin (OPN), osteoprotegerin (OPG) and osteonectin (ON). OPN is secreted by osteoblasts and is found at calcification sites, e.g. during pathological calcification in chronic OM. The cytokine OPG is an inhibitor of bone resorption and consequently bone remodelling. ON is a calcium binding glycoprotein necessary for the maintenance of bone mass and remodelling. It is found in bone matrix and synthesized by osteoblasts. METHOD: A rat model of acute otitis media (AOM) caused by non-typeable Haemophilus influenzae was used. Four days following middle ear inoculation, a myringotomy was performed in six animals. Another group of ten animals was inoculated only. The drum was dissected in two animals from each group on day 4, 7, 14 and 28 post-inoculation, and the expression of OPN, OPG and ON was determined by immunohistochemistry. von Kossa staining determined the deposition of calcium and immune staining for CD68 identified macrophages. RESULTS: Calcium depositions were initially accumulated in the cytoplasm of macrophages and dispersed in the connective tissue layers of the pars flaccida and tensa. Late accumulation occurred in the lamina propria of pars tensa, more extensively in myringotomized ears. OPN expression was found early in inflammatory cells including especially macrophages and late in pars tensa fibrocytes. OPG expression was initially located to inflammatory cells and late to pars tensa fibrocytes and the inner basal membrane of pars flaccida. Some ears displayed a marked pars flaccida expression of ON in the connective tissue matrix on early days and at the inner basal membrane on later days. The latter cases were from myringotomized ears. Otherwise, no apparent differences of marker expression occurred between myringotomized and non-myringotomized animals. CONCLUSION: We conclude that osteopontin, osteoprotegerin and osteonectin are expressed by different cell types in the tympanic membrane during calcification in association with AOM, with or without myringotomy. These molecules may accordingly play a role in the pathogenesis of myringosclerosis, in which macrophages and fibrocytes appear as potential major players.     

First forty-eight hours of developing otitis media: an experimental study

The early inflammatory changes in the tympanic membrane were explored in 2 rat models. Acute otitis media was induced by instillation of Streptococcus pneumoniae type 3 into the middle ear cavity, and otitis media with effusion was induced by blockage of the eustachian tube. Otomicroscopic examination was performed before the rats were painlessly sacrificed at 3, 6, 9, 12, 18, 24, or 48 hours after initiation of the otitis media conditions. The tympanic membrane was studied by light and electron microscopy. Both acute otitis media and otitis media with effusion caused early inflammatory changes of the tympanic membrane, and the pars flaccida was the portion that reacted first. The inflammatory alterations were most pronounced in the acute otitis media model. The course of inflammation showed a bimodal pattern with an early deposition of a filamentous material with a band pattern, typical of fibrin. Despite a fluid-filled middle ear cavity, the inflammatory changes in the otitis media with effusion model were moderate, as was consistent with the clinical appearance of the tympanic membrane.     

Tympanometric changes in an experimental myringosclerosis model after myringotomy.

HYPOTHESIS: The goal of this experimental study was to investigate the specific effect of myringosclerosis on tympanograms in the tympanic membranes of myringotomized rats by using otomicroscopy, tympanometry, and histopathology. BACKGROUND: Myringosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion. The condition involves the hyalinization and calcification of the collagen layer in certain areas of the tympanic membrane. Previous animal experiments suggest an intimate relationship between the formation of myringosclerosis and an increased oxygen concentration in the environment of the wound after myringotomy. The result of a myringotomy therefore is an increased production of free oxygen radicals, initiating irreversible tissue damage involving fibrosis, hyalin degeneration, and finally apoptosis as observed in myringosclerosis. We propose an experimental model specific for creating sclerotic plaques solely on the tympanic membrane and for performing tympanometric measurements on this pure myringosclerosis model without creating any abnormality in the middle ear to test in what proportion myringosclerosis contributes to decrease of amplitude in tympanograms. METHODS: To assess the normal tympanometric values of Wistar albino rats, the pressure and peak admittance of the left middle ears were measured using a semiquantitative computerized clinical admittance meter using a sound frequency of 226 Hz. Twelve animals were randomly selected for the myringotomy group and perforations in the left ears were created. All tympanic membrane perforations in this group had healed and closed prior to the otomicroscopic examination and no pathologic reaction was observed in the external ear canals of rats. Otomicroscopic and tympanometric measurements were carried out on Day 15 and the degree of myringosclerosis was noted before the animals were killed. Twelve specimens in the myringotomy group were histopathologically examined for the presence of myringosclerotic plaques. RESULTS: Under light microscopy, extensive sclerotic lesions were found in the tympanic membranes of the myringotomy group, and these sclerotic deposits were located in the lamina propria. The myringosclerosis occurred predominantly adjacent to the handle of the malleus, but also near the annular region. In all ears with myringosclerosis, the magnitude of the maximum admittance reduced to approximately 50% of the Day-0 values, and this reduction was statistically significant (Z=-3.061, p=0.002). CONCLUSION: The present findings in this study are consistent with the fact that the movement of the tympanic membrane is hampered by lesions of sclerotic material, resulting in a decrease of amplitude in tympanograms (such as Type As) without any effusion or inflammation in the middle ear.     

Clinical observation of acute otitis media in children

This report presents the results of the clinical observation of 96 children under ten years of age with acute otitis media (107 ears) who visited our out-patient clinic from May 1986 to August 1987. The patients were classified into the following three groups according to clinical course: Group 1: 25 cases (26.0%) in which acute inflammatory findings rapidly disappeared and otitis media was cured within two weeks with no evidence of effusion; Group 2: 62 cases (64.6%) in which acute inflammatory findings rapidly disappeared but obvious accumulation of effusion which resolved gradually was observed and in which otitis media was cured from two weeks to three months after onset; Group 3: 9 cases (9.4%) in which persistent accumulation of effusion for more than three months was observed and which required myringotomy and insertion of a ventilation tube and in which a diagnosis of otitis media with effusion was made. The presence or absence of allergic diseases, adenoid symptoms, and otorrhea, or history of tonsillitis had no affect on the prognosis of acute otitis media. However, patients with a history of acute otitis media were at a significantly higher risk of developing the disease chronically. At the time of the resolution of the tympanic redness, abnormal findings in the tympanic membrane and tympanogram (TG), suggestive of the presence of middle ear effusion, were observed in approximately 80% of the patients. Approximately 20% of the patients who showed Type Cs or B in TG at that time developed otitis media with effusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microstructure of tympanic membrane in chronic otitis media: immunohistochemical evaluation

Chronic otitis media (COM) is an inflammatory process involving the middle ear mucosa and the tympanic membrane. The healing and epidermization is mostly impaired by immunological response of the host. Investigating the activity and the function of immunological response elements one can learn the immunological mechanisms taking place in chronic otitis media. The ultrastructural investigations of the tympanic membrane were done on its fragments obtained from 19 patients with COM during middle ear surgery, performed at ENT Department of Medical University of Gdańsk in the years 1997-1999. Immunohistochemical investigations were performed using monoclonal antibodies against tenascin, S-100 protein, Ki 67, CD 31, F VIII, HLA-DR, TGFbeta1 and EGFR. The control group was 11 healthy tympanic membranes from cadavers. The presence of tenascin was proven in all COM tympanic membranes and in 45.5% of those from control group. S-100 protein was present in 88.9% of the patients with COM and absent in control group. Ki 67 was observed in 44.4% of the patients with COM and in 27.3% of the healthy tympanic membranes. Angiogenesis factors (CD 31 and FVIII) were present in 77.8% of the investigated COM tympanic membranes, in control group in 45.5%. HLA-DR expression was observed in 90% COM patients, in control group in 72.7%. Growth factor TGFbeta1 was present in the all cases in mucous and fibrous layer and in 54.5% of healthy tympanic membranes. EGF receptor was present in 60% of COM patients, mainly in epithelial layer of tympanic membrane and in 54.5% of those from control group. The presented investigations confirm the immunological activity of tympanic membrane in chronic otitis media.     

Free radical production by antibiotic-killed bacteria in the guinea pig middle ear

OBJECTIVES: Oxygen free radicals are implicated in the pathogenesis of otitis media Recent investigations with animal models have demonstrated that free radical-mediated damage of the middle ear mucosa, measured as lipid hydroperoxide, occurs when the middle ear cavity is inoculated with Streptococcus pneumoniae. The present study was conducted to examine the effect of antibiotics on free radical-mediated damage in pneumococcal acute otitis media. STUDY DESIGN: Animal model of acute otitis media. METHODS: Seventy-eight guinea pigs underwent bilateral middle ear inoculation with 100 microl of 1) sterile saline as a control, 2) 50 microg/mL amoxicillin, 3) 10(7) colony forming units (CFU)/mL Streptococcus pneumoniae killed with 50 microg/mL amoxicillin, or 4) 10(7) CFU/mL S. pneumoniae. Animals were killed on postoperative day 1 or 5, and the middle ear mucosa was examined for lipid peroxidation as evidence of free radical damage. RESULTS: Mucosal lipid hydroperoxide was significantly elevated compared with control subjects on day 1 in both the antibiotic-killed S. pneumoniae group and the S. pneumoniae-infected group. On day 5, the S. pneumoniae-infected mucosa had significantly higher lipid hydroperoxide levels compared with the antibiotic-killed group and the control subjects. Histological studies confirmed mucosal edema and the presence of inflammatory cells in the infected groups. CONCLUSIONS: Antibiotic-killed bacteria seem to produce free radical-mediated damage to the middle ear mucosa in the early phase of acute otitis media. The clinical implication of this study is that free radical damage to the middle ear mucosa may occur in otitis media despite appropriate antibiotic therapy.     

Otitis media (silent): A potential cause of childhood meningitis

Sixteen temporal bones from 8 infants with otitis media, who died of meningitis, and 6 controls from infants with only otitis media, were studied histologically. All bones contained middle ear effusion and residual mesenchyme, but, unlike the controls, the meningitic cases showed considerable histopathological tissue changes of chronic and acute otitis media and chronic inflammatory cells in the round window membrane and within the perilymph, the modiolus, and the cochlear aqueduct, suggesting the latter as likely portals from the inner ear to the meninges. Since all tympanic membranes were intact and 3 were histologically normal, this silent route of infection warrants medical vigilance.     

Effects of ciprofloxacin-dexamethasone on myringotomy wound healing

OBJECTIVE: To evaluate the effects of the ciprofloxacin-dexamethasone (CDX) combination ototopical treatment after myringotomy on tympanic membrane (TM) healing in ears with eustachian tube obstruction (ETO) and unobstructed ears. STUDY DESIGN: Prospective, randomized, masked, controlled. METHODS: ETO was created in the left ear of 30 rats to induce a model of otitis media with effusion (OME). After 3 weeks, bilateral myringotomy was performed (day 0). Animals were randomized into three groups to receive no treatment or bilateral once daily ototopical treatment with balanced salt solution (BSS, vehicle) or CDX for 13 days. Bilateral otomicroscopy was performed on days 7, 14, and 28. On day 14, five randomly selected animals per group were humanely euthanized and the TM harvested for histology. Three additional rats provided normal negative control ears for histologic comparisons. RESULTS: On day 14, TM perforation healing rates were 100% in all ears of untreated and BSS-treated animals, 89% (8/9) in CDX-treated obstructed ears, and 30% (3/10) in CDX-treated unobstructed ears (P < .05 vs. BSS). On day 28, 100% (5/5) of the CDX-treated unobstructed ears and 80% (4/5) of the CDX-treated obstructed ears were healed. Histology showed initial TM thickening postmyringotomy in all ears but no significant qualitative differences between groups on day 28. CONCLUSION: Myringotomy healing was transiently modulated by treatment with CDX but proceeded normally after CDX discontinuation. This early modulation might enhance middle ear drainage and middle ear concentrations of CDX when tympanostomy tube surgery is performed in patients with active OME and ETO, thus potentially reducing otorrhea and preventing or treating infection. It would not be expected to increase the risk of premature tube extrusion or adversely affect normal healing of the TM after usual spontaneous extrusion.     

Effectiveness of laser-assisted myringotomy for otitis media in children

OBJECTIVE: To evaluate the effectiveness of OtoScan CO2 laser-assisted myringotomy (OtoLAM ESC/Sharplan) for acute otitis media and chronic otitis media with effusion (COME) in children. STUDY DESIGN: Retrospective review of 47 children with refractory acute otitis media (RAOM) or COME more than 3 months in duration in a pediatric otolaryngology practice. METHODS: Laser-assisted myringotomy was performed on 47 patients (79 ears) using the OtoLAM device. There were 28 children (ages 0.50-3 years) with RAOM and 19 children (ages 0.58-15 years) with COME. RESULTS: A total of 57.4% of procedures were considered treatment failures. Failures occurred in 53.6% of patients with RAOM on average +/-SD 3.89 +/- 2.16 weeks after the procedure and in 63.2% of patients with COME on average +/-SD 7.25 +/- 5.57 weeks after the procedure. Age, sex, microorganism isolated, myringotomy size, wattage, and laterality did not predict outcome. Ventilation tube insertion was performed in 27 (57.4%) patients. Two patients have persistent tympanic membrane perforations at 2 years. CONCLUSIONS: Laser-assisted myringotomy in children with RAOM and COME was associated with a high incidence of recurrence or persistence of disease and with perforation of the tympanic membrane. Recommendations for use of the OtoLAM should include discussion of high failure rates and the strong likelihood of subsequent ventilation tube insertion. The OtoLAM remains an option for office-based ventilation of the middle ear for families and patients where general anesthesia is a concern.     

Influence of nasal allergic reactions on the clearance of middle ear effusion

In order to investigate the influence of nasal allergic reactions on the clearance of middle ear effusion, an animal model of nasal allergy and otitis media with effusion was produced in the same guinea pigs simultaneously by passive sensitization with serum of homologous animals containing IgE antibodies (for nasal allergy) and by inoculation of immunocomplex into the tympanic cavity (for otitis media with effusion). Usually, middle ear effusion appeared within 2 to 3 days and disappeared within 7 to 9 days after the inoculation of immunocomplex. Three days after the inoculation of immunocomplex, intranasal antigen challenge was performed three times daily and continued until the animals were killed. Disappearance of middle ear effusion appeared to be delayed in animals in which nasal allergic reactions were induced. Middle ear effusion was not found in those ears that were not inoculated with immunocomplex. Findings of the present study indicate that IgE-mediated allergic reactions of the mucous membrane lining the nose, nasopharynx, and eustachian tube constitute a factor indicative of a chronic state of disease, rather than a cause of otitis media with effusion.     

Iontophoretic anaesthesia of the tympanic membrane

Anaesthesia of the tympanic membrane by iontophoresis of lidocaine is a painless and safe method for myringotomy and grommet insertion. Thirty-nine patients with serous otitis media and II patients with Ménière's disease had their tympanic membranes anaesthetized by iontophoresis of lidocaine; analgesia was perfect for all of them. In the patients with serous otitis media, the insertion of grommets was carried out easily and without pain. Major problems or complications have not been encountered during this study.     

The role of laser assisted tympanostomy (LAT) in treating allergic children with chronic serous otitis media

OBJECTIVES: To assess various prognostic factors influencing the outcome in paediatric patients with serous otitis media, who have undergone laser assisted tympanostomy without ventilation tube placement. Emphasis is given to children with allergies who underwent the procedure. METHOD: Laser assisted tympanostomy was performed on a total of 130 ears (92 individuals) with chronic otitis media with effusion. To determine the quality of patient outcome, the following parameters were evaluated: external auditory canal anatomy, type of anaesthesia used, tympanic membrane and middle ear fluid characteristics, myringotomy size, a history of allergies and the laser device parameters. RESULTS: Multivariable statistical analysis demonstrated that the presence of allergies in children with chronic serous otitis media is significantly correlated with a poor outcome (P < 0.0047). Moreover, the presence of a thick tympanic membrane and/or high viscosity (glue) fluid in the middle ear cavity can also independently influence patient outcome (P < 0.025). Simultaneous adenoidectomy and/or tonsillectomy, type of anaesthesia (general versus local), external canal anatomy (wide or narrow) and sex, were not statistically important prognostic factors. The type of anaesthesia used, myringotomy size and the laser device parameters were not found to be associated with patient outcome. CONCLUSION: A history of allergies, the presence of a thick tympanic membrane and/or high viscosity fluid in the middle ear cavity are all contraindications for laser assisted tympanostomy without tympanostomy tubes, in children who suffer from chronic serous otitis media. The selection criteria for this procedure in the paediatric population are addressed in detail.     

5-Fluorouracil ointment for the treatment of otitis media with effusion

OBJECTIVES/HYPOTHESIS: Our aim was to evaluate the combined effect of 5-fluorouracil (5-FU) and myringotomy for the treatment of otitis media with effusion (OME). OME is usually treated with medication, myringotomy, or insertion of a ventilation tube (VT). Except for VT insertion, however, treatment effects are short-lived. VT insertion has numerous sequelae: increased susceptibility to infection, large perforation of the tympanic membrane, cholesteatoma, and eventual hearing deterioration. We estimated the depressant action of 5-FU on normal cell proliferation in vitro. In addition, clinically, we assessed whether 5-FU has the potential to prolong the effect of myringotomy. STUDY DESIGN: An in vitro study and a clinical study were conducted. MATERIALS AND METHODS: In study I, fibroblasts harvested from the peritoneum of three green fluorescent protein transgenic mice were cultured with different doses of 5-FU. After 2 weeks, their proliferation rates were compared. In study II, patients (54 males, 47 females) were selected randomly from a group of patients with intractable OME. Myringotomy with or without a single dose of 5-FU ointment (approximately 0.10-0.30 mg) was performed in group I (n = 64) and group II (n = 37), respectively. The natural closure rates of the tympanic membrane were assessed in both groups. RESULTS: In vitro, 5-FU inhibited the growth of fibroblasts in a dose-dependent manner. The average time to tympanic membrane closure was 20.5 days in group I and 8.1 days in group II. No adverse events were observed in either group. CONCLUSIONS: Topical application of 5-FU ointment is useful in prolonging the effect of myringotomy. 5-FU ointment therapy is easy, safe, and cost-effective and may be of wide application.     

分泌性中耳炎临床疗效观察

目的随访分泌性中耳炎患者经单纯鼓膜切开、鼓膜切开冲洗灌药后的恢复情况，探讨有效的治疗方法。方法对2006年1月-2008年12月因分泌性中耳炎住院手术治疗的病人共168例进行随访，实际回应预约随访者40例（67耳）。术后随访时间为6个月-3年，通过手术前后I临床表现、纯音测听、声导抗及鼓膜改善情况评估各组疗效。结果单纯鼓膜切开组与鼓膜切开冲洗灌药组的有效率分别是55.56％和74.19％，两组之间无统计学差异。结论单纯鼓膜切开和鼓膜切开冲洗灌药是治疗分泌性中耳炎的有效方法。     

Acute otitis media develops in the rat after intranasal challenge of Streptococcus pneumoniae

OBJECTIVES/HYPOTHESIS: The rat is a frequently used animal model for middle ear research. To date, acute otitis media (AOM) has been evoked after instillation of bacteria directly into the middle ear cavity or after traumatizing the tympanic membrane. The purpose of the study was to examine whether, with an intact tympanic membrane and middle ear cavity, intranasally deposited bacteria cause AOM and how tympanic membrane stimulation influences this procedure. STUDY DESIGN: In vivo, murine model. METHODS: In a rat model, Streptococcus pneumoniae, type 3, was intranasally inoculated for 5 consecutive days. The tympanic membrane was treated with saline or with compound 48/80 or was left untreated. The development of AOM was evaluated by otomicroscopy, light microscopy, and middle ear culture. RESULTS: Ninety percent of the ears developed AOM. However, when the tympanic membranes were treated with saline or compound 48/80, only 40% and 57%, respectively, developed AOM. In all, 23 of 40 ears developed AOM and 20 ears showed growth of bacteria. CONCLUSION: Repeated intranasal deposition of S. pneumoniae, type 3, causes AOM in the rat. The development of AOM can be influenced by tympanic membrane stimulation.