Myringosclerosis develops within 9h of myringotomy

Laser, radiofrequency or tympanostomy knife? Comparison of surgical methods in tympanostomy treatment of young children and predictive value of tympanometry

OBJECTIVES

To investigate tympanostomy tube (TT) treatment in young children, with special interest in bloodless surgical methods (laser and radiofrequency), myringosclerosis formation and tympanometric testing.

METHODS

This prospective study includes 76 children whose 121 ears with middle ear effusion were treated with tympanostomy tubes. Myringotomy was performed with CO₂ laser in 37, radiofrequency in 40 and myringotomy knife in 44 ears. The ears were evaluated with otomicroscopy and tympanometry preoperatively and postoperatively every 3-4 months until spontaneous tube extrusion.

RESULTS

All tubes extruded spontaneously (mean 12.8 months, range 3-36 months), with no persistent perforations or cholesteatomas. CO₂ laser and radiofrequency inserted tympanostomy tubes extruded faster (mean 11 months) compared to incisional myringotomy (mean 15 months, p = 0.002). Myringosclerosis was noted in 25 (21%) ears after treatment. There was a tendency to less myringosclerosis with bloodless techniques, but the difference was not significant. Flat tympanograms on the day of procedure predicted continuation of ventilation problems also after TT treatment (p = 0.003). Ears with preoperative type B tympanogram had significantly more myringosclerosis 21/75 (28%) compared with type A and C tympanograms 4/41 (10%) (p = 0.032).

CONCLUSIONS

While all myringotomy methods were effective and safe, the traditional incisional myringotomy with a tympanostomy knife is still a good, feasible and cost-effective myringotomy method. No surgical removal of tympanostomy tubes is needed before 3 years of uncomplicated tympanostomy treatment. Tympanometry turned out to be a useful tool in prediction of post TT treatment ventilation problems of the middle ear.

The Effect of Curcumin on the Prevention of Myringosclerosis in Rats

OBJECTIVE

The aim of this study was to investigate the preventative effect of oral curcumin (CMN) on myringosclerosis (MS) in an experimental rat model.

METHODS

The study included 21 female Wistar albino rats randomly separated into three groups. Group 1 was given no treatment (control group). In Group 2 and Group 3, the tympanic membrane (TM) was perforated using a sterile ear pick. The rats in Group 3 were administered oral CMN 200 mg/kg/day. All rats were sacrificed after 16 days. Otomicroscopic and histopathologic examinations were performed on the tympanic membranes.

RESULTS

Histopathologic examinations revealed that there were statistically significant differences between Group 2 and Group 3 in terms of MS degrees (p<0.001) and mean thicknesses of TMs (p<0.001), but there were no differences between Group 1 and Group 3. In respect of MS detected by otomicroscopy, a statistically significant difference was determined between Groups 1 and 2 (p<0.001) and between Groups 2 and 3 (p<0.01), but there was no significant difference between Group 1 and Group 3 (p=0.575).

CONCLUSION

Orally administered CMN can prevent myringosclerosis formation in experimentally induced myringotomies.

Effect of Topical Dexamethasone for Preventing Experimentally Induced Myringosclerosis

Objective

We aimed to examine the effect of topical dexamethasone by otomicroscopic and histologic examinations for preventing myringosclerosis induced by myringotomy in rat tympanic membranes.

Methods

Twenty-one Sprague Dawley rats (42 ears) were randomly divided into the following three groups after otomicroscopic examinations: experimental surgical group (5 rats), control group (8 rats), and study group (8 rats). The rats of all the groups underwent myringotomy in both tympanic membranes. Other than myringotomy, no additional procedure was performed for the rats in the experimental surgical group. In the control group, 0.9% NaCl was applied to the ears, whereas in the study groups, topical dexamethasone was applied to the ears. These applications in the control and study groups were repeated for nine days. On the 10th day of the study, the rat ears of all groups underwent otomicroscopic and histologic examinations. The prevalence and process of myringosclerosis were evaluated by otomicroscopic examination, whereas inflammation, membrane thickness, and myringosclerosis intensity were evaluated by histologic examination.

Results

The growth of myringosclerosis with otomicroscopic examination was lesser in the study group in which topical dexamethasone was applied than the control and the experimental surgical groups. Moreover, it was observed that myringosclerosis effected fewer quadrants in the study group.Histologic examinations revealed that inflammation was significantly lesser in the study group than in the experimental surgical and control groups. The average membrane thickness values were significantly lesser in the study group than in the experimental surgical group. With respect to myringosclerosis growth, no statistically significant difference was observed among all groups, whereas with respect to myringosclerosis intensity, the rat ears in the study group were less severely affected.

Conclusion

Thus, our study results suggest that applying topical dexamethasone after myringotomy has positive effects on limiting the intensity and prevalence of myringosclerosis.

The effect of Nigella sativa oil on prevention of myringosclerosis in a Guinea pig model

OBJECTIVES

In this study, our aim was to identify the possible effects of Nigella sativa L. (NS) [blackcumin] seed oil on the prevention of experimentally induced myringosclerosis (MS).

MATERIALS AND METHODS

Fourteen Guinea pigs were used and they were divided into three groups. Tympanic membranes (TM) of all animals were perforated and then group I was treated with saline soaked gel foams as a control group, group II was treated with 0.5 ml NS oil soaked gel foams at 0, 24 and 48 h and group III was treated with 5 ml NS oil orally at 0, 24, 48, 72 and 120 h. After 15 days, all animals were euthanized. Tympanic membranes were evaluated macroscopically and histopathologically.

RESULTS

Groups I showed extensive myringosclerosis in contrast to those of Groups II and III which had significantly less changes (p < 0.05). The fibrosis and inflammation in the lamina propria of the tympanic membranes of Groups I was found to be significantly more pronounced (p < 0.05). The tympanic membranes were found to be significantly thinner in Groups II and III when compared with Groups I (p < 0.05).

CONCLUSIONS

The results of this study suggested that topical or oral administration of NS oil supressed the inflammation and fibroblastic activity in the lamina propria of the myringotomized TMs of the Guinea pigs. For providing further evidence to use plant extracts as antioxidant and antiinflammatory therapy after myringotomy or ventilation tube insertion, further clinical studies with larger population will be essential.

The effect of Hypericum perforatum L. (St. John's Wort) on prevention of myringosclerosis after myringotomy in a rat model

OBJECTIVES

The purpose of this study was to identify the possible effects of Hypericum Perforatum (HP) on the prevention of experimentally induced myringosclerosis (MS).

METHODS

Twenty eight Wistar Albino rats were used and they were divided into four groups. Tympanic membranes of all animals were perforated and then group I had no treatment as a control group, group II had treated with olive oil only, group III had treated with HP orally and group IV had treated with HP topically.

RESULTS

Groups I and II showed extensive myringosclerosis in contrast to those of Groups III and IV which had significantly less changes (p<0.05). The inflammation and fibrosis in the lamina propria of the tympanic membranes of Groups I and II were found to be significantly more pronounced (p<0.05). The tympanic membranes were found to be significantly thinner in Groups III and IV when compared with Groups I and II (p<0.05).

CONCLUSIONS

The results of the present study suggested that oral or topical administration of HP extract after myringotomy suppressed the inflammation and fibroblastic activity in the lamina propria of the myringotomized TMs of the rats. Further clinical studies with larger population using HP and other antioxidants will be essential to provide further evidence for use of antioxidant therapy in patients with myringotomy and ventilation tube insertion for otitis media with effusion.

Morphological alterations in the tympanic membrane affected by tympanosclerosis: ultrastructural study

The ultrastructure of tympanoslerotic tissue, surgically excised from patients, has been studied with particular reference to the morphological changes of the connective tissue components and mineralization. Detailed analysis revealed the combination of degenerative and fibroplastic alterations, especially in the circular fibrous layer of the thickened lamina propria. In the biological material in this study the authors recognized different stages of calcium plaque development with discrete, moderate, and severe degree of mineralization. Extracellular matrix vesicles, with or without calcareous deposits, released by degenerating fibroblasts were prominent. In these biopsies no distinct morphological features of an inflammatory reaction were seen.

Analysis of gene expression profiles in tympanic membrane following perforation using PCR Array in rats--preliminary investigation

OBJECTIVES

The goal of this work was to identify genes, known to be involved in the skin wound healing, that express differentially in the healthy and injured tympanic membrane (TM), and designate the molecules potentially beneficial for treatment of TM perforation. The molecular mechanisms controlling the course of TM regeneration are far from being elucidated.

METHODS

Twenty rats had their tympanic membranes perforated, while four served as a control. Animals were sacrificed on either days 1, 2, 3, 5 and 10 post injury, and TMs were immediately dissected and frozen in liquid nitrogen. Total TM RNA was isolated and reversely transcribed. qPCR was performed using Rat Wound Healing RT(2) Profiler PCR Array (QIAGEN) containing primers for 84 genes.

RESULTS

Statistically significant changes in the expression of 42 genes were found in various stages of TM healing. The increased expression of genes taking part in the inflammatory reaction (interleukin 6, granulocyte and macrophage chemotactic proteins) was observed from day 2. The expression of several genes of extracellular matrix components and their remodeling enzymes was also changed. Among growth factor genes: Vegfa, Igf1 and Hbegf showed increased expression at the beginning of the healing process, while Hgf expression was highest on day 3.

CONCLUSIONS

Several changes in the expression of genes involved in remodeling of extracellular matrix point to important role of connective tissue in TM healing. The molecules accelerating this process, like HbEGF and HGF, seem to be good candidates for further evaluation of their possible use in clinical treatment.

Everolimus-coated tympanostomy tube on rat tympanic membrane

OBJECTIVES

Everolimus is an immunosuppressant and an antiproliferative macrolide agent which is used for coronary stent coating for local inhibition of in-stent restenosis. The aim of this study was to evaluate the effect of everolimus-coated tympanostomy tubes in rat tympanic membrane.

STUDY DESIGN

Prospective controlled animal study.

MATERIALS AND METHODS

Twenty-one Sprague-Dawley rats were included in the study. They were bilaterally myringotomized. An everolimus-coated fluoroplastic tympanostomy tube was inserted into one ear of each of the rats (everolimus-coated TT Group; n=21) and a standard fluoroplastic tympanostomy tube was applied to the contralateral ear of the same rats (Standard TT Group; n=21). Tympanic membranes and tubes were routinely examined otomicroscopically every other day for two months. Then the membranes were harvested and evaluated histologically.

RESULTS

In everolimus-coated tubes, the tube obstruction was found to be significantly lower than in standard tubes (p<0.05). The tube extrusion rate was less for everolimus-coated tubes than for standard tubes, but no statistically significant difference was observed between the two tubes. There was no statistically significant difference in the incidence of otorrhea between two tubes. Histopathological examination under light microscope revealed that everolimus-coated tubes resulted in less fibrosis and less inflammation in tympanic membranes than standard tubes (p<0.01).

CONCLUSION

The study shows the potential role of everolimus-coating of tympanostomy tubes in reducing tube obstruction. In addition, inflammatory reaction and fibrosis were observed to be significantly less with these tubes.

Levels of reactive oxygen species in rat tympanic membranes after incisional versus radiofrequency myringotomy

OBJECTIVE

A close relationship between reactive oxygen species (ROS) and myringosclerosis, which is a common complication of myringotomy, was recently reported. The objective of this study was to measure ROS levels directly in rat tympanic membranes using luminol-aided chemiluminescence (CL) in order to compare the levels of ROS after incisional and radiofrequency (RF) myringotomy.

METHODS

Fifteen Sprague-Dawley rats were separated into three groups of five animals each. Bilateral myringotomies were made using an appropriate myringotomy lancet in Group 1 and RF in Group 2. Group 3 served as the control group with no myringotomy. Twenty-four hours after the procedure, all tympanic membranes were inspected with an otomicroscope and then excised for the measurement of ROS using luminol-aided CL.

RESULTS

The mean ROS level in Group 1 was significantly higher than that in Groups 2 and 3 (p<0.05 for both). The difference in mean ROS level between Groups 2 and 3 was not significant (p>0.05). Otomicroscopy revealed increased vascularity and vessel dilation in all tympanic membranes that underwent myringotomy. Vascular dilation was observed in the annular region in the vessels that passed along the long arm of the malleus, in addition to the vessels feeding the anterior and posterior tympanomalleolar folds.

CONCLUSIONS

Although the relationship between ROS and the development of myringosclerosis after myringotomy has been demonstrated, the present study is the first to compare incisional and RF myringotomy based on the measurement of ROS levels. Our results indicate that the increase in ROS due to myringotomy was greater following incisional myringotomy than RF myringotomy.

Antioxidant effect of pomegranate extract in reducing acute inflammation due to myringotomy

OBJECTIVE

To assess the effect of pomegranate extract on acute inflammation due to myringotomy.

DESIGN

Prospective, randomised study.

SUBJECTS

Thirty Sprague-Dawley rats were divided into three groups. Group one constituted controls. Group two underwent myringotomy. Group three underwent myringotomy and also received 100 µl/day pomegranate extract, via gavage, one day before and two days after surgery. Following sacrifice 48 hours after myringotomy, the animals' right ears were used to determine the concentration of reactive oxygen species, using the chemiluminescence method; left ears were used for histological study.

RESULTS

Reactive oxygen species levels were significantly decreased in group three compared with group two (p < 0.01). The density of inflammatory cells in group three was significantly less than that in group two (p < 0.01). Lamina propria thickness and vessel density were also significantly decreased in group three compared with group two (p < 0.01).

CONCLUSION

Our results indicate that oral pomegranate extract decreases reactive oxygen species concentration and acute inflammation in the tympanic membrane after myringotomy.

Myringosclerosis after tympanostomy tube insertion: relation with tube retention time and gender

OBJECTIVE

To determine relationship between myringosclerosis and tube retention time and sex in children with chronic otitis media with effusion who were treated with tympanostomy tube insertion. Also, the relationship between myringosclerosis both sex and initial age of tube insertion were investigated.

METHODS

A total of 101 children (195 ears) were reviewed. Ears were divided into four groups according to retention time of tympanostomy tubes. Group I: Retention time of tympanostomy tube less than 6 months. Group II: Retention time of tympanostomy tube from 6 months to 12 months. Group III: Retention time of tympanostomy tube of 12 months or more. Group IV: Myringotomy group without tympanostomy tube insertion.

RESULTS

The order of the myringosclerosis rates were as follows from the highest to lowest one; group III (44.1%), group II (42.4%), group I (14.3%), and group IV (7.7%). Myringosclerosis was more common in group I compared with group IV, but the difference was statistically not significant (p>0.05). There were no statistically significant differences in myringosclerosis rates between the group II and group III (p>0.05). On the other hand, statistically significant differences were observed in myringosclerosis rates between group I and group II (p<0.05), and between group I and group III (p<0.05); also similar significant differences were present in myringosclerosis rates between group IV and group II (p<0.05), and between group IV and group III (p<0.05). There was no significant difference between preschool age group and school age group. Myringosclerosis was observed in 40% of boys and in 51.2% of girls.

CONCLUSION

Myringosclerosis is frequent in patients who underwent tympanostomy tube insertion. The frequency of myringosclerosis is much higher in tympanic membranes with tympanostomy tube insertion than tympanic membranes with myringotomy, and the location of sclerotic plaques does not always correspond to the tympanostomy area. The myringosclerosis rate was increased when the tympanostomy tubes stay on tympanic membrane for a long time. Highest myringosclerosis rates were observed if the extrusion time was 12 months or longer. In our analysis, sex and initial age of tube insertion were not significant factors for the development of myringosclerosis after extrusion of tympanostomy tubes.

Acute tympanic membrane perforations and the early immunological response in rats

CONCLUSIONS

This study showed that macrophages, B cells, and T cells occurred at different frequencies, localizations, and times after acute laser tympanic membrane perforation. Immunological cells were most prevalent in the proliferative mass adjacent to the annulus region. The cellular immunological response in freshly perforated eardrums was unexpectedly aggressive.

OBJECTIVES

To study the occurrence of immunocompetent cells during the healing process of fresh perforated tympanic membranes. The information could be used to develop alternative outpatient procedures in the cure of chronic perforations, replacing conventional surgery.

MATERIALS AND METHODS

A laser myringotomy was carried out in Sprague-Dawley rats, which were sacrificed at 3 and 6 days after the myringotomy. Tympanic membrane sections were stained immunohistochemically according to the avidin-biotin method, targeting macrophages, B cells, and T cells. Semi-quantification was performed; positive cells were counted and mean values were calculated.

RESULTS

Macrophages and B cells were most frequent at day 6 and T cells at day 3 after laser myringotomy. B cells were the most prevalent studied cell type. T cells peaked at day 3, after which they decreased in number. Most immunocompetent cells were observed in the proliferative mass at the edge of the perforation.

Evaluation of the polymorphism in the Toll-like receptor 4 (TLR4) genes of tympanosclerosis patients

OBJECTIVE

Although eardrum perforations which endure etiopathogenesis for a long-time and middle ear infections are proposed for causing the tympanosclerosis (TS), tympanosclerosis emerges in some chronic otitis media (COM), some of them do not appear although a continuing COM and enduring perforation last. In this study, the effect of the molecular reasons which display genetic differences in TS formation is evaluated; our aim is to determine the Asp299Gly polymorphism frequencies in the TLR4 gene of patients with TS who have COM, and patients who do not.

MATERIALS AND METHODS

Patients who have undergone COM surgery, were divided into two groups of 50 persons who were selected in accordance with the fact, whether they had TS in their middle ear cavity or not during operation. 100 healthy persons who had similar demographic data, were evaluated as the control group. The DNA isolation was executed by using standard methods with peripheric blood specimen of the diseased group and control group. The Restriction Fragment Length Polymorphism method was used in determining the Asp299Gly allel in the TLR4 gene. Items of 249 bc for the wild tip (Asp) post-restriction enzyme segment wild tip (Asp) allel, and 23 bc and 196 bc post-restriction enzyme segment polymorphic allel (Gly) were obtained.

RESULTS

TLR4 Asp299Gly polymorphism (10%) was asserted in a total of five specimens in the diseased group with TS. TLR4 Asp299Gly polymorphism was found positive in only one (2%) of the 50 phenomenons in the group without TS. TLR4 Asp299Gly polymorphism was found positive in six (6%) of the 100 phenomenons in the control group. The positive polymorphism in phenomenons with TS was significant in accordance with statistics, when compared with the group without TS (p<0.05). However, although the polymorphism rates were higher than the rates of the control group, it was not statistically significant (p>0.05).

CONCLUSION

TS may not appear in many patients who had undergone middle ear infection, and had perforation for many years. The polymorphism in arteriosclerosis in the TLR4 gene which caused the inflammatory cytokines oscillation recognize the bacterial LPS, was also accused. It is engrossing to find out from the results of our study on a restricted number of patients, and on only one gene, that molecular reasons which display genetic differences can also be effective in forming TS. Serial researches of greater dimensions are required.

Lack of plasminogen does not alter the early inflammatory response following a tympanic membrane perforation: a study in plasminogen-deficient mice

CONCLUSIONS

The results of the present study show that the early inflammatory response in plasminogen (plg)-deficient mice is not altered compared to that in wild-type (wt) mice. Therefore the chronicity of the perforation in the long-term healing experiment cannot be explained by an impairment of the early inflammatory response, but rather by an impairment in activation of the inflammatory cells. These findings give further insight into the mechanisms resulting in a clinically seen chronic tympanic membrane (TM) perforation and thus possible therapeutic strategies to replace today's conventional surgical treatment of these perforations.

OBJECTIVES

Plg has been shown to play an essential role in the healing of TM perforations. In plg-deficient mice a completely arrested healing reaction was seen, resulting in a chronic TM perforation. The mechanisms involved seem to be an abundant neutrophil recruitment, an accumulation of macrophages, an arrested keratinocyte migration, and a massive deposition of fibrin along the TM tissue. However, the exact functional role of plg in the early inflammatory response during healing of TM perforation remains unclear. This study aimed to evaluate the early inflammatory response, mainly the occurrence of macrophages and neutrophils, during the first 48 h following a perforation in the pars tensa (PT) of the TM, in mice lacking the plasminogen gene compared to the corresponding response in wt mice.

MATERIALS AND METHODS

The TMs were perforated in 45 plg-deficient and 39 wt mice. Otomicroscopic evaluation was performed at 3, 6, 9, 12, 18, 24, and 48 h after the perforation was made. Mice were harvested at all time points and prepared for morphology including immunohistochemistry (IHC). IHC was performed with antibodies targeting macrophages, neutrophils, T and B cells, cytokeratin, and fibrin(ogen). Morphometry was performed regarding the volume percentage of TM tissue occupied by the different inflammatory cells.

RESULTS

Perforation of the TM resulted in early otomicroscopic changes of the pars flaccida (PF) in both genotypes. Infiltration of inflammatory cells to PF and the presence of edema occurred as early as 6 h after the perforation was made, in both plg-deficient and wt mice. Morphometry did not reveal any significant differences between the genotypes concerning the occurrence of inflammatory cells. In contrast to the PF, the PT showed only sparse reactions during the experimental period. Furthermore, the migration pattern of keratinocytes did not differ between the genotypes throughout the experimental period.

The effect of caffeic acid phenethyl ester on the prevention of experimentally induced myringosclerosis

OBJECTIVES

Myringosclerosis is a common sequela of ventilation tube insertion for the treatment of the otitis media with effusion. Several antioxidants have been identified to prevent myringosclerosis. The objective of this study was to investigate the effect of caffeic acid phenethyl ester (CAPE) on the prevention of experimentally induced myringosclerosis.

METHODS

Thirty-five Sprague-Dawley rats were unilaterally myringotomized. The rats were divided into four groups randomly: group 1 received no treatment, group 2 received intraperitoneally administered saline and group 3 received intraperitoneally administered CAPE. The tympanic membranes were examined by otomicroscopy on the 15th day after treatment. The membranes were then harvested and evaluated histologically by light microscopy.

RESULTS

The tympanic membranes from group 1 showed extensive myringosclerosis; those from group 2 showed a similar occurrence of myringosclerosis. However, group 3 had a reduced occurrence of myringosclerosis by otomicroscopic evaluation. Under light microscopic examination, the lamina propria of the pars tensa was found to be thicker and more sclerotic in groups 1 and 2 when compared with group 3.

CONCLUSIONS

Systemic treatment with CAPE was found to be effective in the prevention of sclerotic lesions in myringotomized rat tympanic membranes.

The effect of Vitamin E treatment on the development of myringosclerosis after ventilation tube insertion

OBJECTIVES

Recent studies have established the relationship between the reactive oxygen species and myringosclerosis. Furthermore several antioxidants have been known to prevent myringosclerosis. All the previous studies supporting this hypothesis have been performed on animals. The aim of our study is to investigate the possible effect of Vitamin E on the development of tympanosclerosis after VT insertion on human subjects.

METHODS

72 children undergoing myringotomy and VT insertion were included in the study. Vitamin E was applied to the right ear and no treatment was applied to the left ear. Both ears were examined at the end of 9 months with otomicroscopy. Myringosclerosis formation at the end of the study period was noted for each ear.

RESULTS

Myringosclerosis was found in 33 of the 144 ears. The overall incidence was 22.9%. While 22 (30.6%) of the 72 left ears showed myringosclerosis otomicroscopically, in only 11 (15.3%) of the 72 right ears that were treated with Vitamin E was myringosclerosis observed at the end of the study period. Of these nine cases were bilateral.

CONCLUSION

Animal studies have well documented the development of myringosclerosis after myringotomy and VT insertion and beneficial effects of different antioxidants. Our study has shown similar results in human subjects. Further clinical studies consisting of a larger patient population are needed to bring about routine clinical use of antioxidants in myringotomy and VT insertion.

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.

Vitamin e-coated tympanostomy tube insertion decreases the quantity of free radicals in tympanic membrane

OBJECTIVE

Tympanosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion causing hearing disability. It is associated with an increased production of free radicals (also known as reactive oxygen species) after myringotomy. Vitamin E is a scavenger of different free radicals by working as an antioxidant. The aim of the present study was to evaluate the effect of vitamin E-coated tympanostomy tube insertion at quantity of free radicals in rat tympanic membrane.

METHODS

This prospective, controlled animal study consisted of male Sprague-Dawley rats divided into two groups of 10 animals each. Ordinary silcone tubes were applied to the right ears of the first group and vitamin E-coated silcone tubes were applied to the right ears of the second group. The left ears were used as controls. Then, the animals were killed and chemiluminescence measurements were made for tympanic membranes.

RESULTS

Reactive oxygen species levels (ROS) were significantly increased in right ears of the first group when compared with the control ears (P < .0001), and the levels were statistically significant decreased in right ears of the second group as compared with the operated ears of the first group (P < .0001). The free radical levels of right and left ears in the second group were similar.

CONCLUSIONS

Our results indicate that vitamin E-coated tube insertion decreases the quantity of reactive oxygen species in tympanic membrane after myringotomy and tympanostomy tube insertion.

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.

The role of experimental myringosclerosis in interpretation of tympanograms and its possible clinical implications

Myringosclerosis (MS) is hyalinization and calcification of the collagen layer in certain areas of the tympanic membrane (TM) and appears as white chalky patches in otomicroscopy. One of the most common sequela from the use of grommets is the development of MS and its rate in the tubed ear ranges between 44% and 54% during long term follow-up. Among tympanometric configurations, type As tympanograms may indicate ossicular fixation, tympanosclerosis or otitis media with effusion. In case of multiple pathologies (e.g., MS and otitis media with effusion), it is not possible to evaluate the effect of a specific pathology in the absence of other, with otomicroscopy and tympanometry. We believe that the movement of TM is hampered by lesions of sclerotic material, thus resulting in decrease of amplitude in tympanograms without any effusion in middle ear. Now, we propose an experimental model specific for creating MS solely on TM and for performing tympanometric measurements on this pure MS model without creating any pathology in the middle ear, to test in what proportion this specific pathology contributes to decrease of amplitude in tympanograms. A myringotomy in rat's TM admits ambient air into the middle ear cavity, resulting in a relatively hyperoxic condition. The result of a myringotomy therefore is an increased production of free oxygen radicals, initiating irreversible tissue damage involving fibrosis, hyalin degeneration and finally apopitosis as observed in MS. After the closure of perforations, tympanometric measurements can be made on this pure MS model. When evaluating a child for suspected otitis media with effusion, the results of the experimental model might have far-reaching clinical implications and might provide suitable target for prevention of unnecessary myringotomies especially in the pediatric age-group.

Determination of Reactive Oxygen Species in Myringotomized Tympanic Membranes: Effect of Vitamin E Treatment

OBJECTIVES/HYPOTHESIS

Recent studies have established a strong relationship between the development of myringosclerosis and reactive oxygen species (ROS). The aims of the present study were to directly detect ROS in the tympanic membrane and middle ear mucosa of rats by measuring luminol amplified chemiluminescence, to evaluate the changes in the levels of ROS after treatment with vitamin E, and to examine the possible changes in the tympanic membranes otomicroscopically and histologically.

STUDY DESIGN

Prospective controlled animal study.

METHODS

Forty healthy Sprague-Dawley rats were divided into five groups of eight animals each. Animals in all groups except group 1 were bilaterally myringotomized. Group 2 received no treatment, group 3 was treated with topical olive oil, group 4 received topical vitamin E, and group 5 received intramuscular vitamin E. After 24 hours of myringotomy, tympanic membranes were examined otomicroscopically; thereafter, tympanic membranes and middle ear mucosa were peeled off. The right ears of the animals were used for biochemical assay, and the left ears were used for histological study.

RESULTS

Reactive oxygen species levels were significantly decreased in group 4 with topical application of vitamin E compared with untreated and myringotomized animals in group 2. Reactive oxygen species levels were also decreased in group 5, although the decrease was not statistically significant when compared with groups 2 and 3. Histological studies confirmed sclerotic changes in the untreated myringotomized animals. The tympanic membranes of animals in groups 2 and 3 showed a white, chalk-like pattern of sclerotic changes, whereas animals in groups 4 and 5, with the exception of two animals in group 5, lacked these changes.

CONCLUSION

Although the relationship between the development of myringosclerosis and ROS had been well documented previously, the present study is the first that has directly measured the levels of ROS in the tympanic membrane and middle ear mucosa. These results are relevant because they correlate with histological findings. It has also been demonstrated that topically applied vitamin E is effective in decreasing the ROS levels.

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.

Myringotomy delays the tympanic membrane recovery in acute otitis media: a study in the rat model

BACKGROUND/HYPOTHESIS

Acute otitis media is a major cause of visits to pediatric health care providers. Myringotomy in uncomplicated acute otitis media is debatable today. The study addressed this problem through the otomicroscopic and histopathological observations of the events occurring in the tympanic membrane during the first week after myringotomy.

STUDY DESIGN

Randomized study in an experimental animal model.

METHODS

Under anesthesia, the left middle ear of 36 Sprague-Dawley rats was inoculated with Streptococcus pneumoniae type 3. Forty-eight hours later, at day 0, four animals were immediately killed and the remaining animals were randomly assigned into a myringotomy group (n = 16, myringotomy on the left ear) and a non-myringotomy group (n = 16, otomicroscopy without myringotomy). Otomicroscopy and killings were performed in series of four animals from each group at days 1, 2, 4, and 7 after myringotomy. Tympanic membranes were collected after fixation and processed for light and electron microscopy.

RESULTS

All inoculated ears showed a manifest acute otitis media at day 0. An intense infiltration by inflammatory cells and edema distorted severely the tympanic membrane structure. These findings decreased the following days. However, inflammation as evaluated by the thickness and the cytoarchitecture of the tympanic membrane layers, recovered significantly faster in the membranes in the non-myringotomy group. At day 7, all tympanic membranes in the myringotomy group were closed by a hypertrophic keratinizing epithelium and a remodeling connective tissue layer, whereas the animals in the non-myringotomy group had a residual edema in the lamina propria.

CONCLUSIONS

The present infectious model induced an intense inflammatory reaction within the entire structure of the tympanic membrane. Myringotomy provoked a delayed recovery from the inflammatory process within the tympanic membrane. Therefore, if applicable to human conditions, the use of myringotomy in the management of acute otitis media should be restricted to selected cases of acute otitis media.

Myringotomized tympanic membranes cultured in vitro do not develop myringosclerosis

The aim of this study was to evaluate the development of myringosclerosis in in vitro-cultured tympanic membranes. Sprague-Dawley rats were myringotomized bilaterally and the tympanic membranes were excised after sacrifice. The explants were placed in inserts in wells filled with a nutrient medium. Every second day the tympanic membranes were photodocumented and after 9 days the explants were prepared for histology. On the 4th day the explants had attached to the bottom of the inserts and the specimens had thickened. From the perforation borders and the dissection edges a thin outgrowth was extending across the surface. By Day 9 the perforation had clearly diminished in size when examined in a stereomicroscope. In a light microscope the keratin layer was seen to protrude towards the centre of the perforation and, at the borders, epithelial cells were bridging the gap. Neither the pars tensa nor the pars flaccida showed any sclerotic lesions. The pars flaccida had thickened and the basal cells of the outer keratinized epithelium had invaded the connective tissue. Inflammatory cells were sparse in both the pars tensa and pars flaccida. The in vitro-cultured myringotomized tympanic membrane therefore shows a similar healing pattern to that in vivo. However, inflammatory reactions are sparse and there is no development of myringosclerosis.

The effect of local administration of N-acetylcysteine in perforated rat tympanic membrane: an experimental study in myringosclerosis

Myringosclerosis (MyS) is a common sequela of acute and chronic otitis media and ventilation tube treatment of serous otitis media. We aimed to study the effect of topical administration of N -acetylcysteine (NAC) on MyS by assessment of otomicroscopic evaluation, lipid peroxidation and nitric oxide (NO) (nitrite/nitrate) levels in experimental myringotomized rat tympanic membrane. Thirty adult rats were used and the upper posterior quadrant of the tympanic membranes of rats was myringotomized. Thereafter, they were divided into four groups. Group I received no treatment, group II was treated with saline, groups III and IV were treated with topical NAC (0.1 ml of 6 and 12 mg ml(-1), respectively). The levels of nitrite/nitrate and malondialdehyde (MDA) were measured in serum samples. In the otomicroscopic evaluation, non-treated and saline treated ears (controls) showed extensive occurrence of myringosclerotic plaques. Groups III and IV showed fewer occurrences of sclerotic plaques. There was no significant difference between groups III and IV regarding the development of MyS. The development of myringosclerotic lesion was found to be significantly different between NAC treated groups (III and IV) and the control groups (I and II). The levels of nitrite/nitrate of both groups III and IV were significantly lower than the control groups. The levels of MDA of these groups were also significantly lower than the control group. The relationship between groups III and IV was not statistically significant for the levels of nitrite/nitrate and MDA. We conclude that the topical treatment of NAC reduces the levels of MDA and NO products in rats. These results suggest that topical NAC application may be useful for the prevention of MyS.

Macrophages and possible osteoclast differentiation in the rat bullar bone during experimental acute otitis media, with reference to tympanosclerosis

HYPOTHESIS

Large osteoclast-like cells, labeled by using monoclonal antibodies directed against macrophages, are participating in a bone remodeling process in the rat bullar bone after induced experimental acute otitis media, leading to tympanosclerosis.

BACKGROUND

In humans, tympanosclerosis is a sequale of chronic otitis media. It causes hearing disability, especially if the ossicles or the inner ear are affected. No successful treatment is available. To evaluate the inflammatory stages that may lead to tympanosclerosis, the current study was performed.

METHODS

Sprague-Dawley rats were exposed to a pneumococcus Type 3 solution into the middle ear. The rats were killed at 3, 6, and 10 days after inoculation. Sections from the ear specimen were stained immunohistochemically. Antibodies used were directed against macrophages.

RESULTS

Positive cells were seen in the tympanic membrane, in the middle ear mucosa, and close to the tympanic membrane insertion into the bone. Macrophages appeared to be linearized adjacent to the bullar bone, both on the inner and on the outer bullar wall. These cells had the appearance of osteoclasts.

CONCLUSION

A differentiation of macrophages to osteoclasts is possible during induced otitis media in the rat, initiating a bone-remodeling process leading to tympanosclerosis.

Degranulation of mast cells provokes a massive inflammatory reaction in the tympanic membrane

OBJECTIVE

The pars flaccida is extremely rich in mast cells. On stimulation the mast cells release preformed and de novo synthesized inflammatory substances. The purpose of this study was to examine how these mast cell substances provoke inflammatory changes in the tympanic membrane.

STUDY DESIGN

In vivo, murine model.

METHODS

In a rat model, the mast cell secretagogue compound 48/80 was applied locally to the tympanic membrane on 4 consecutive days and the ensuing inflammatory changes were evaluated by otological, light, and electron microscopy 3, 6, 9, 12, 18, 24, 36, and 48 hours and 4, 6, and 8 days later.

RESULTS

Degranulation of the mast cells occurred within 3 hours of applying compound 48/80. Release of the mast cell substances coincided with an inflammatory event characterized by a two-stage reaction: an edema stage, peaking 6 hours after application, followed by a massive invasion of inflammatory cells, peaking at 24 and 48 hours. Pars flaccida and pars tensa were both involved, pars flaccida showing the earliest changes. Pars tensa exhibited the same biphasic reaction as pars flaccida, but approximately 6 hours later.

CONCLUSIONS

The mast cells of the pars flaccida have the capacity to elicit an intense inflammation of the tympanic membrane. The biphasic reaction pattern resembles that observed in experimental otitis media, suggesting involvement of the mast cells in this inflammatory condition of the middle ear.

Detection and localization of interleukin-6 in the rat middle ear during experimental acute otitis media, using mRNA in situ hybridization and immunohistochemistry

OBJECTIVE

Otitis media is one of the most common diseases among children. A well-known sequela of acute, chronic, and secretory otitis media is tympanosclerosis. With the exception of surgery, there is no causal treatment available for this condition, which may cause hearing disabilities. This study aimed to describe the localization of interleukin (IL)-6 mRNA and its gene product in the rat middle ear during pneumococcal otitis media. IL-6 is known to be involved in inflammatory and bone remodeling processes.

METHODS

Using an experimental model of pneumococcal acute otitis media, the expression of interleukin IL-6, was analyzed. Sprague-Dawley rats were sacrificed at different time points varying from 1 h to 6 days intervals after inoculation. The middle ears were analyzed by messenger RNA in situ hybridization, and by immunohistochemistry with cell-type specific antibodies directed against IL-6.

RESULTS

Transcripts of IL-6 were observed only on day 1 post-inoculation, whereas the final gene product was observed at all intervals after inoculation. IL-6 was localized in the bony part of the bulla nearest to the mucosa, around mucosal vessels, and in the ciliae of the mucosal epithelium. The results demonstrated that IL-6 was synthesized locally as early as 1 h after bacterial middle ear challenge, and that although transcription could not be detected after 24 h, the cytokine product persisted for at least 5 days after the infection was introduced.

CONCLUSIONS

IL-6 was shown to be produced early in the inflammatory process during induced pneumococcal otitis media in the rat. No production was seen after 24 h although the protein remained in the tissue for at least 5 days. IL-6 could initiate a differentiation of macrophages to osteoclasts and thereby participate in a bone remodeling process leading to tympanosclerosis development.