[Clinical analysis of tympanosclerosis: characteristics and treatment]

OBJECTIVE

To explore the clinical characteristics, diagnosis and surgical management of tympanosclerosis.

METHOD

The data of 73 patients who underwent surgery for tympanosclerosis were retrospectively analyzed with respects to the clinical characteristics, diagnosis and management.

RESULT

Seventy-three patients with tympanosclerosis (involving 73 ears) , including 17 patients with sclerosis of tympanic membrane (type I), 23 patients with fixed Malleus-incus complex (type II), 8 (type III) with fixed stapes, and 25 (type IV) with extensive typannosclerosis. Sclerosis was seen most frequently in the malleus, incus and attic, followed by the tympanic membrane, incudomalleolar joint and other regions. Audiometry was performed for all the patients 1 weeks before and 1 year( the least) after operation, which were (51.70 ± 14.93)dB HL and (36.24 ± 11.58) dB HL respectively, with success rate 83% (61/73).

CONCLUSION

Most of the patients suffer from conductive hearing loss. Teatment of the sclerosis around stapes is a key point. Acording to the sites of lesion and hearing level, hearing structures should be reconstructed by the rules of tympanoplasty and stapes surgery.

Surgery of isolated malleus fixation due to tympanosclerosis

The aim of the present study was to describe our surgical approach for isolated malleus fixation in patients with tympanosclerosis and to analyze the postoperative results. A total of 30 patients presented with isolated malleus fixation were operated. The fixation was reached via canalplasty. Fixated areas were cleaned without damaging the ossicle. Pre- and postoperative audiometric results were evaluated for each patient. Improvement of the pure-tone average (PTA) by at least 10 dB and an air-bone gap (ABG) of less than 20 dB after 12 months of follow-up was accepted to indicate success. The recovery of the postoperative PTA and ABG measurements was significant. Pre- and postoperative PTA was 48.00 ± 11.86 and 24.90 ± 12.45 dB, respectively (p < 0.001). According to PTA measurements, 40-50 dB recovery was achieved in four (13.3 %) patients, 31-40 dB in six (20 %) patients, 21-30 dB in ten (33.3 %) patients, and 11-20 dB in five (16.6 %) patients, with a total success rate of 25/30 (83.2 %). Pre- and postoperative ABG levels were 38.95 ± 9.92 and 16.10 ± 7.79 dB (p < 0.001), respectively. The ABG level was between 0 and 10 dB for 8 (26.6 %) patients, and 11-20 dB for 16 (53.3 %), with a total success rate of 24/30 (80 %). In cases of isolated malleus fixation with tympanosclerosis, performing a canalplasty to clean the sclerotic plaques without damaging the normal anatomy of the ossicle system using a diamond burr is a safe surgical option that provides significant recovery in hearing levels.

[The relationship between ossicular status and conductive hearing loss in cholesteatoma]

OBJECTIVE

To investigate and analyze the characteristic of destructive ossicular chain and it's impact on air-bone gap (ABG) among patients with cholesteatoma.

METHOD

Data from 204 cases (213 ears) undergoing an initial surgery for cholesteatoma were retrospectively reviewed to evaluate the relationships between preoperative pure tone audiometry data and intraoperative assessment of individual ossicular destruction.

RESULT

Incus was the most significantly affected ossicle. Furthermore, the destruction of malleus and stapes was often accompanied by the destruction of incus. A partially eroded incus caused significantly increase in ABG from that of an intact incus with cholesteatoma abutting (P < 0.05). A partially eroded incus and a partially eroded stapes caused significantly increase in ABG compared to a partially eroded incus (P < 0.05). A completely eroded incus caused significantly increase in ABG compared to a partially eroded incus (P < 0.05). False fibre-connected would significantly influence on ABG in some ossicular chain erosion patterns (P < 0.05). Cholesteatoma abutting an intact ossicle significantly altered average ABG compared to a normal ossicle (P < 0 01).

CONCLUSION

Different ossicular chain erosion pattern caused different degrees of ABG.

The morphological findings of malleus and incus in a case of Marfan's syndrome

In Marfan's syndrome, which is a connective tissue disorder of hereditary origin, collagenous tissue development and bone synthesis are generally altered in addition to the occurrence of many systemic deformities. External ear, stapes, and vestibular aqueduct pathologies are reported as some of the otological deformities. However, the malleus and incus pathologies of the ear are not reported in any study. In the morphometric measurements carried out, the distance between the malleus head and manubrium was found to be 9.8 mm. When similar measurements were carried out for the incus, the distance between the upper part of the incus body and tip of the long process was found to be 6.9 mm. All of these measurements were detected to be greater than in normal people. It can be concluded from this study that in Marfan's syndrome, in addition to the musculoskeletal alterations particularly in bone synthesis, the ossicular chain in the middle ear is also affected.

Malleus–stapes assembly: experience with two prostheses

Tympanoplasty is often a necessary part of middle-ear surgery, the most common defect being that between an intact, mobile stapes and the malleus handle. The most readily available tissue is the patient's incus, reshaped to bridge the space between an intact stapes and the malleus. When the incus cannot be used, the hydroxyapatite Wehrs incus prosthesis® can be used as an alternative.

Twenty-six patients had an autograft incus ossiculoplasty and 20 patients underwent modified Wehrs incus prosthesis ossiculoplasty. The average post-operative air–bone gaps (ABGs) were 16.2 dB hearing loss (dBHL) and 17.2 dBHL, respectively. Air–bone gap closure to within 15 dBHL was achieved for 48 per cent of incus autografts and for 57 per cent of Wehrs prostheses, and to within 20 dBHL for 77 per cent and 62 per cent, respectively. Over four years follow up, the reconstruction was stable for each group, the ABGs being 17.7 dBHL and 17.1 dBHL, respectively.

[Malleostapedotomy in the pathology of the incudomalleolar complex combined with fixation of the stapes]

INTRODUCTION

Stapes fixation combined with disorders of the incudo-malleolar complex disorders requires a sound transmission reconstruction that often is difficult to solve. This circumstance can turn up in several pathologies and also in revision surgery for otosclerosis.

PATIENTS AND METHODS

We present our experience with four patients that underwent to malleostapedotomy with removal of the malleus anterior ligament and the malleus anterior apophysis.

RESULTS

We discuss the previous findings in each case. Two patients reached a gap closure and the other two patients obtained an auditive gain without complete gap closure.

DISCUSSION

We set out the ethiology of malleus and incus hipomobility. We do a bibliographic review on the results of this technique in revision stapedectomy.

Malleus head fixation: histopathology revisited

CONCLUSIONS

Malleus head fixation is a rare but not exceptional pathology. It may be apparently congenital or acquired, and can be associated with stapes fixation. In the acquired secondary process two histological types of malleus head fixation were found: the first corresponded to non-tympanosclerotic bone remodeling and the second to localized tympanosclerosis.

OBJECTIVE

To describe the histopathologic features of malleus head fixation and to correlate them with its clinical appearance.

MATERIAL AND METHODS

Ten patients with surgically proven malleus head fixation were included in this series. A fixed malleus head was resected via a transcanal approach in six patients, and attic bony fragments fixing the malleus head were removed via a mastoidectomy without disruption of the ossicular chain in four. Histopathologic studies were performed for both types of malleus head fixation.

RESULTS

Three types of acquired malleus head fixation were defined in accordance with the surgical and histopathological findings. Histologically, the first type presented with normal bone tissue, the second was characterized by non-tympanosclerotic bone remodeling and the third presented with a localized tympanosclerotic focus in the tympanic cavity.

Histologic changes in the anterior mallear ligament and the head of the malleus in otosclerosis

OBJECTIVE

To determine ossicular and anterior mallear ligament (AML) changes in otosclerosis.

STUDY DESIGN AND SETTING

Hyalinization of AML was graded as follows: none, patchy, or diffuse in 95 temporal bones (TBs) with otosclerosis: 52 with stapedial fixation (SF); 43 without fixation (NSF); and 52 age-matched controls. Fixation of the head of the malleus was noted.

RESULTS

Hyalinization with SF was 17 none, 23 patchy, and 12 diffuse; with NSF it was 16 none, 20 patchy, and 7 diffuse; and in controls, 23 none, 24 patchy, and 5 diffuse. There was no significant difference in hyalinization among groups and no correlation between degree of hyalinization and age. The malleus head was fixed in 4 TBs with SF.

CONCLUSION

Based on our findings, we do not believe that there is a relationship between hyalinization of the AML and otosclerosis; however, otosclerosis with SF seems to be a predisposing factor for fixation of the head of the malleus.

Experimental and Clinical Studies of Malleus Fixation

OBJECTIVES/HYPOTHESIS

Preoperative clinical diagnosis of malleus fixation can be difficult. "Fixation" of the malleus can be caused by various disorders or diseases: fibrous tissue, bony spurs, and neo-osteogenesis around the malleus head or stiffening of the anterior malleal ligament. The conductive hearing loss produced by these disorders or diseases has not been well characterized. The study goals were 1) to determine the effects of various types of malleus fixation using a cadaveric temporal bone preparation and 2) to assess the clinical utility of umbo velocity measurements in preoperative differential diagnosis of malleus fixation and stapes fixation.

METHODS

Umbo and stapes velocity were measured in 18 fresh cadaveric human temporal bones with laser vibrometry before and after controlled application of adhesives to the malleus, stapes, or both ossicles.

RESULTS

Each simulated pathological condition produced a specific degree of loss in stapes velocity: stiffening of anterior malleal ligament, 0 to 8 dB; fibrous tissue around malleus head, less than 10 dB; bony bar to malleus head, 10 to 30 dB; and extensive neo-osteogenesis around malleus head, greater than 35 dB. Simulated malleus fixations generally produced similar reductions in both umbo and stapes velocity. Stapes fixation reduced stapes velocity with little change in umbo velocity. Because the change in stapes velocity would be similar to conductive hearing loss, experimental results were directly compared with clinical measurements of umbo velocity in surgically confirmed cases of malleus or stapes fixation. The effects of malleus and stapes fixations between the clinical and experimental data were similar.

CONCLUSION

The study showed that measurements of umbo velocity and air-bone gap can enable one to diagnose malleus fixation and specifies how to differentiate malleus from stapes fixation.

[Spontaneous healing of various types of rat tympanic membrane perforation]

OBJECTIVE

To investigate the spontaneous healing process of various types of rat tympanic membrane perforation, study the perforation healing mechanism.

METHODS

Fifty rats were divided into five groups in randomization, and performed perforations phi = 2.5 mm, 1 mm, respectively in the center of tympanic membrane pars tensa, posterior marginal perforation (phi = 1.5 mm) in pars tensa, the handle of malleus cauterized with chromic acid after tympanic membrane 3/4 excision, and perforation (phi = 1.5 mm) in the center of pars flaccid, The histology of the perforations healing process was observed with light microscope.

RESULTS

The epithelia retracted in the early stage after perforation. The epithelia near the annulus and manubrium showed hyperplasia. The epithelia hyperplasia also appeared the intact annulus region remote to the perforation. The middle connective tissue layer reacted later than the epithelial layer. The defects were closed first by the accumulation of the epithelial cells. The difference of healing time had no statistics significance between the big and small perforations. One ear perforated, but the other side intact ear appears no change. The epithelia didn't migrate into the tympanic cavity in the posterior marginal perforations. All the perforations healed after the manubriums of the malleus were damaged. Perforations in pars flaccid healed more quickly.

CONCLUSIONS

The normal migration of the epithelia of the tympanic membrane played an important role in the healing of perforation. The generation center was located near tympanic annulus and manubrium of the malleus, so the protection of these two regions was very important in the middle-ear surgery.

[Experimental investigations of CO2 laser application in middle ear ossicles]

BACKGROUND

During the last few years, several laser systems have been applied for procedures in middle ear surgery. In this study, we determined the technical parameters for the dissection of the middle ear ossicles with the CO(2) laser and analyzed the histological findings.

METHODS

The malleus necks of 16 human temporal bones were dissected under standardized conditions using a CO(2) laser with a power output between 35 and 55 kW/cm(2). The specimens were fixed and histological probes of 50- micro m thickness were prepared.

RESULTS

The laser outputs led to crater diameters from 0.14 to 0.55 mm. As an analogy between laser energy and thermal tissue destruction, three zones of thermal damage were differentiated: a cinder zone, a carbonization zone, and a zone of dehydration. The metrical dimensions of these zones did not show any correlation to the applied laser energy.

CONCLUSIONS

The data of this study show that commercially available CO(2) lasers are sufficient for a safe and effective partial resection of middle ear ossicles using a power output of 35 kW/cm(2).

The anterior and superior malleal ligaments in otosclerosis: a histopathologic observation

HYPOTHESIS

The aim of this study was to assess, in otosclerosis, whether the anterior and superior malleal ligaments show histologic changes that can lead to reduced malleal mobility and eventual fixation, and also to evaluate whether these changes are related to the degree of histologic otosclerosis.

BACKGROUND

Fixation of the malleus seems to be one of the most controversial clinical entities in the acquired condition of otosclerosis. It has even been postulated that persistent conductive deafness, or progression of conductive deafness after initial improvement after stapedotomy, could be due to unsuspected malleus fixation.

METHODS

Fifty eight temporal bones with known otosclerosis and 43 normal temporal bones were selected. In addition, 10 temporal bones of fetuses and children were also studied. Otosclerosis of the footplate and otic capsule was graded as none, mild, moderate, and severe. The histologic changes in the ligaments also were graded from none to severe.

RESULTS

The median ages of patients in the otosclerotic and normal groups were 62 and 60 years, respectively. In the anterior malleal ligament of the otosclerotic bones, 10% mild (+), 60% moderate (++), and 30% severe (+++) degrees of hyalinization were observed. In the anterior malleal ligament of the nonotosclerotic bones, 14% showed no hyalinization, 24% had only a tinge of hyalinization (minimal), 51% had mild (+) hyalinization, and 11% had moderate (++) hyalinization. Superior ligament hyalinization appears to be related to the severity of anterior ligament hyalinization. The severity of otosclerosis in the footplate or the otic capsule did not appear to be related to the severity of hyalinization.

CONCLUSION

From this study, it is apparent that otosclerotic bones have a significantly high incidence of hyalinization of the anterior malleal ligament. This seems to be related to the duration rather than the severity of otosclerosis. It is important to properly evaluate malleal mobility during all stapes surgery.

Malleus fixation: clinical and histopathologic findings

The goals of this study were to review important clinical and histopathologic features of malleus fixation. Ten clinical cases and 10 histopathologic cases of malleus fixation were identified. For the clinical cases, preoperative clinical data, surgical findings, and preoperative and postoperative audiometric findings were reviewed. Ninety percent of the clinical cases achieved significant reduction of the air-bone gap after operation. Two thirds of these cases had an air-bone gap of 10 dB or less, and the remainder had air-bone gaps between 20 and 28 dB after operation. For the temporal bone cases, clinical data, histopathologic findings, and other otologic diagnoses were reviewed. Malleus fixation can be idiopathic or a result of trauma, chronic otitis media, or developmental anomalies. It is a cause of hearing loss that is likely to be more common than the number of diagnoses would indicate. Certain audiometric findings may lead one to suspect the diagnosis. The surgical approach used depends on the individual anatomy, and surgery is usually highly effective in improving hearing.

Malleus ankylosis: a clinical, audiometric, histologic, and surgical study of 123 cases

OBJECTIVE

Malleus ankylosis is a cause of conductive hearing loss that can be difficult to assess, particularly in association with otosclerotic stapes fixation. The aim of this study is to seek the clinical and audiometrical features unique to this pathology.

STUDY DESIGN

The study design was a review of malleus ankylosis cases and an analysis of functional results after ossiculoplasty.

SETTING

The study was performed at Jean Causse Clinic in France.

PATIENTS

The authors reviewed a series of 123 ears in 112 patients who underwent surgery for incudo-mallear ankylosis from January 1991 to September 1997.

INTERVENTION

The surgical technique depends on the type of pathology encountered. In case of associated stapedial fixation, a stapedotomy with vein graft interposition and reconstruction with a total prosthesis will be performed during a same step.

MAIN OUTCOME MEASURES

Clinical evaluation, preoperative and postoperative audiometrical evaluation, operative findings, histologic examination, and postoperative functional results.

RESULTS

In our series, a postoperative air-bone gap smaller than 10 dB was obtained in 77% of cases. These results confirm the possibility of managing both pathologies in a single surgical step.

CONCLUSION

Incudo-mallear ankylosis remains an unusual pathology but should be systematically assessed during surgery and preferably after separation of the incudo-stapedial joint. A preoperative diagnosis is difficult to ascertain; some audiometrical features allow a suspicion. In this series, it is shown that otosclerosis can be responsible for ankylosis as seems to be confirmed by the two cases presented in this study.

Evaluation of a cement incus replacement prosthesis in a temporal bone model

In reconstruction of the ossicular chain for a damaged incus, it is important that the incus replacement prosthesis (IRP) length is ideal in order to provide optimal tension between the tympanic membrane or malleus and stapes head to achieve the best post-operative hearing result. Even though the length of commercially available IRPs can be adjusted, it still may be difficult to achieve clinically. We describe experiments in a human temporal bone model using dental cement as an IRP after removal of the incus. This cement IRP (CIRP) hardens in situ and becomes the length of the gap to be spanned so that tension should be ideal. Two different CIRPs were studied; one was a conventional rod-type CIRP connecting either the umbo or mid-malleus handle to the stapes head. The second was a Y-shaped CIRP (Y-CIRP), connecting two sites on the malleus to the stapes head. The wide Y-CIRP connected the malleus head and umbo to the stapes head, while the narrow Y-CIRP connected the malleus neck and mid-handle to the stapes head. The acoustic performance of these experimental CIRPs was studied using a laser Doppler vibrometer system in 12 fresh human temporal bones. The CIRP demonstrated better acoustic performance than conventional IRPs studied previously in the same model. While all the CIRPs showed similar function below 2.0 kHz, the narrow Y-CIRP appeared best above 3.0 kHz. A prosthesis of this type may have an acoustic advantage over conventional IRPs.

Myringosclerosis develops within 9h of myringotomy

The aim of the present experimental study was to elucidate the temporal development of myringosclerosis. Twenty-four Sprague-Dawley rats were myringotomized bilaterally. At 3, 6, 9, 12, 18, 24, 30, 36, 48, 60, 72 and 84 h after the myringotomy, 2 animals at each time were examined otomicroscopically and thereafter sacrificed. The pars flaccida and pars tensa were excised and prepared for light- and electron-microscopic studies. Otomicroscopically, myringosclerosis was visible in the pars tensa 24 h after myringotomy, whereas no sclerotic lesions were noted in the pars flaccida. Histologically, sclerotic lesions were present in the pars tensa and pars flaccida 9 and 12 h, respectively, after myringotomy. The pars flaccida responds promptly with an inflammatory reaction characterized by abundant macrophages. Myringosclerosis develops promptly after myringotomy and its establishment is related to an inflammatory reaction.

[Fixed mallear head syndrome]

Fixed head malleus syndrome is a rare anatomoclinical entity first described by Goodhill in 1966. We present a series of 9 patients who underwent surgery between 1991 and 1997 and discuss the technical procedures used and functional outcome. Ossicular mobility can be re-established with two surgical methods. The more simple method consists in a classical incus transposition with malleus neck section. The more physiological method consists in drilling the synostosis fixing the malleus without disrupting the ossicular chain; stapedotomy is associated in certain cases (Type III).

Congenital bony fixation of the malleus

Bony fixation of the malleus seems to be one of the most controversial clinical entities among various congenital disorders of the auditory ossicles. According to various theories, it could be caused by trauma, chronic infection of the ear, otosclerosis or even development failures in the tympanic cavity itself. Histological analysis of 1,108 temporal bones showing a normal middle ear structure was performed. All bones were cut in serial sections of 20 microns. Audiograms and the data on ear trauma or chronic infection were analysed from case histories belonging to each bony specimen. Bony fixation of the malleus was found in 14 cases. It was almost always unilateral. The most frequent site of the fixation was the lateral epitympanal wall. The forms of fixation differed from a thin bony lamella to a solid bony bridge. The mallear ligaments were not involved in any case. No relationship to chronic ear infection, ear trauma or otosclerosis was found. Only a slight conductive hearing impairment up to 20 dB was recorded in 6 out of 14 cases. The most probable predisposing anatomical factors for the onset of the bony fixation of the malleus and the most recent preoperative diagnostic possibilities are discussed.

[Mallear epidermosis. An unusual form of open mucous otitis]

The presence of keratin in the middle ear cavity is usually associated with the diagnosis of cholesteatoma or epidermoid metaplasia. Analysis of a series of 18 cases suggests that it may correspond to a specific entity developing in the course of severe or long-lasting opened chronic otitis. This condition, we called mallear epidermosis, is characterized by: i) a perforation of the tympanic membrane lining the handle of the malleus and the umbo; ii) a proliferation of keratin surrounding the handle of the malleus and diffusing into the mesotympanum on the internal side of the tympanic membrane, without matrix; and iii) a mild inflammation of the middle ear epithelium. The process is usually limited to the mesotympanum and does not extend towards the attic and the posterior cavities. Epidemiological, clinical, pathophysiological, and histological features allow this entity to be distinguished from cholesteatoma and epidermoid metaplasia. Management is either medical consisting of local treatment and microaspiration, or surgical including resection of the umbo, removal of the tympanic membrane invaded by the adherent hyperkeratotic layers and repair by conventional underlay myringoplasty. This report emphasizes the need for a clear identification of the various types of chronic otitis media presenting with keratin in the middle ear, as they do not share the same course and do not require the same therapeutic management.

Early structural changes in the rat tympanic membrane during pneumococcal otitis media

The early inflammatory reaction in the rat tympanic membrane was studied during the first 36h following inoculation of Streptococcus pneumoniae type 3 in the middle ear cavity. Otomicroscopic examination showed only minor signs of inflammation in the early stages although changes at the light microscopic level were pronounced. This reaction differed significantly between the pars flaccida and pars tensa of the tympanic membrane. Three hours after inoculation, edema and infiltration with polymorphonuclear leukocytes and macrophages were found in the pars flaccida whereas in the pars tensa no polymorphonuclear leukocytes were noted until after 12h. This reaction was most prominent after 36h. In the pars flaccida, mitoses occurred frequently among the cells of the simple squamous epithelium, which changed into a double-layered cuboidal epithelium. These findings demonstrate that an inflammatory reaction starts earlier in the pars flaccida than in the pars tensa of the tympanic membrane.

Effects of low humidity on the rat middle ear

Secretory otitis media is common in the winter, and the possible risk factors are numerous. This study examines the effect of low humidity on the middle ear using a Sprague-Dawley rat model: 23 test rats housed for 5 days in a low-humidity environment (10% to 12% relative humidity) and 23 control rats housed at 50% to 55% relative humidity. Microscopic ear examinations were graded for otitis media with effusion (OME) before testing and on test days 3 and 5. The mucosa of the middle ears and eustachian tubes was examined histopathologically. Significantly more effusions were observed in the low-humidity group on test days 3 (P = .003) and 5 (P = .01), but no intergroup histopathologic differences were noted. We conclude that a low-humidity environment contributed to the development of OME in the test animals, and that low-humidity warrants further investigation as a contributing factor in childhood middle ear disease.

Histopathology of ossicular implants

Ossicular and cortical bone grafts maintain their morphologic structure for long periods of time and show varying amounts of replacement of nonviable bone by new bone through a slow process of creeping substitution. Cartilage grafts develop chondromalacia, lose stiffness, and tend to be resorbed over time. Plastipore prostheses elicit foreign body giant cell responses with microscopic biodegradation of the implants. There is a great need for the study of well-documented human temporal bone cases with in situ ossicular implants.

Cholesteatoma: ossicular destruction in adults and children

The records of 148 adults (aged 14 years and older) presenting previously untreated aural cholesteatomas are analysed with particular emphasis on ossicular destruction and other bony lesions in the middle ear. The findings are compared with those obtained in an earlier study of 63 children (aged 13 years and younger), also with untreated cholesteatomas. The rate of stapes and malleus destruction was similar in adults and children. The rate of incus destruction was significantly higher in adults. Semicircular fistulas as well as facial paralysis were also more prevalent amongst adults. Therefore, the notion of childhood cholesteatoma aggressiveness cannot be related to its effect on these bony structures. It may stem from its higher recurrence rate and from the more troublesome post-operative mastoid cavities, which are often larger in children than in adults.

Mongolian gerbil tympanic membrane. Normal and with induced otitis media

Otoscopic observation of the tympanic membrane is the most effective noninvasive means of diagnosing and following the course of experimental otitis media in animal models of the disease in both short-term and in longitudinal studies. Because of the difficulty of viewing the entire tympanic membrane of the gerbil model of otitis media without manipulation, we present methods of visualizing and color illustrations of the normal tympanic membrane of the Mongolian gerbil, Meriones unguiculatus. These are compared with illustrations of animals with acute experimental otitis media. An artist's rendition of the entire normal gerbil tympanic membrane is presented. These methods and illustrations will enable investigators to more rapidly and easily adopt the Mongolian gerbil as an animal model for studies of otitis media.

[Scanning electron microscopy studies in arthritic changes in the malleus incus joint and reflections on the function of the middle ear muscles]

The surfaces of immobilised incus and malleus joints were studied with the scanning electron microscope. The hyaline cartilage showed arthritic changes similar to osteoarthritic big joints of the body. A direct radiologic magnification technique could likewise demonstrate typical arthritic signs. Comparing findings from histologic studies in the literature, we could demonstrate that the intact hyaline cartilage degenerates if the ossicles are immobilised. The minimal static friction of the intact smooth joint surface is a prerequisite for its assumed role namely protection of the inner ear against hazardous pressure changes. A hypothesis is developed to the effect that the movement of the ossicles, necessary for lubrification and nutrition of the hyaline cartilage, is maintained by the two middle-ear muscles. Their function, which had not been explained so far could thus be interpreted--besides a possible effect on sound transmission--as preserving the intact joint surfaces of the ossicles. Nature seems to set great store by the importance of the middle ear joints, as shown by the development of a new joint structure in an implanted homoio-incus.

Dynamics of otosclerosis-like lesions in LP/J mice

The LP/J inbred mouse is the first known animal to spontaneously develop otosclerosis-like bone lesions in the middle and inner ear. These abnormal bone foci resemble human otosclerotic lesions, are inherited, and produce a progressive hearing loss. On the basis of histological evaluation alone, it was unclear whether these otosclerosis-like lesions in LP/J mice develop suddenly or gradually as in human otosclerosis. To study the dynamics of lesion formation, four different colored fluorochrome bone labels were given in sequence to postpubertal LP/J mice and CBA/J mice as normal controls. All of the otosclerosis-like lesions incorporated at least one fluorochrome, and half were labeled with two or more markers indicating continuous lesion growth over many weeks. It appears that otosclerosis-like lesions in LP/J mice develop during early adulthood and progress gradually as in human otosclerosis.

Ossicular and otic capsular lesions in LP/J mice

Otosclerosis is an inherited disease in which abnormal bone growth results in ossicular fixation and hearing loss. Although the disease affects up to 10% of humans, it has not been observed in other animals. The LP/J inbred mouse has been found to develop abnormal bony lesions of the middle ear which resemble human otosclerosis. In this study of 113 temporal bones from LP/J mice, we found that the lesions develop after puberty and involve only the ossicles and the otic capsule. The most frequent site of involvement was the incus (46.9%), followed by the anterior crus of the stapes (31.3%), the malleus (14.2%), the otic capsule (14.2%), and the stapes footplate (8%). Cochlear hair cell loss was progressive throughout the lifespan of these animals. Although this disease is not identical in histologic appearance to human otosclerosis, understanding its disease process may shed light upon the pathophysiology of the human disease.

Homografts of the tympanic membrane with malleus; histological study in cat

The present experiments on cats were performed to explore the process of survival and take of transplanted homografts of tympanic membrane with malleus, the homografts being respectively preserved in 4% and 0.5% formalin (pH 7.0) solutions, and to explore the reaction of middle ear mucosa of the recipient. The present study also included gross and histopathological examinations of the eardrum and observation of fibers of the lamina propria of the transplanted tympanic membrane by means of polarizing microscopy and of vascularization by intravascular India ink injection. The experiments conducted using a total of 96 cats yielded results leading to the following conclusions. 1) After six months the transplanted tympanic membrane showed nearly normal histologic features, with a fibrous layer between the lining epithelial and thin mucosal layers. The middle ear mucosa also became thinner and was covered with ciliated epithelium at this stage. 2) As regards vascular distribution, most vessels entered from the peripheral regions to become distributed all over the eardrum with mutual anastomoses. 3) Fibrous tissues of the lamina propria of the pars tensa of the transplanted eardrum remained intact over the six month period. 4) The transplanted malleus was neither destroyed not absorbed, and proved to survive well with active vascularization. 5) The microscopic changes observed in the middle ear mucous membrane of the recipient showed non-specific reactions to Gelfoam. The grafts were not subjected to immunological rejection. Homograft thus offer the best grafting material, but seemed to show poor resistance to infection.

Temporal bone histopathologic features in Fanconi's anemia syndrome

A histopathologic study of the temporal bones from a 7-year-old girl with Fanconi's anemia syndrome demonstrated (1) hemorrhage in the submucosal layer and the cavity of the middle ear and mastoid, massive in the right ear; (2) hypocellularity of the bone marrow; (3) minor but multiple anomalies of the middle ear; and (4) hypodevelopment of the hook portion of the cochlea and reduced overall length of the cochlear duct. The histopathologic features of these temporal bones appears to suggest that congenital anomalies of the inner ear, as well as those of the external and middle ears, would be possible causes of the deafness that accompanies Fanconi's anemia syndrome.

[Tympanosclerosis (author's transl)]

With a new method--that is embedding non-decalcified tissue in Methylmethacrylat and then slicing it--the patho-histological phenomenon of the tympanosclerosis can be demonstrated with 4 patients on account of the material acquired with the tympanoplasties showing rare localisations (such as stapedial tendon, mastoidale). According to our experiences (42 cases) tympanosclerosis is mainly to be found in female patients not older than 40 years. The genesis of the tympanosclerosis and its reparation through surgical techniques are discussed.

[The implantation of lyophilized and gamma-sterilized allogenetic incus and of lyophilized and gamma-sterilized xenogenetic malleus (calf) in rabbits and humans (author's transl)]

The histological reactions to the implantation of allogenetic and xenogenetic lyophilized and gamma-sterilized material into the middle ear of rabbits and men is described. In contrary to the behaviour of allogenetic material the xenogenetic shows a clear minor tendency of revitalisation. The reason is the antigen-antibody-reaction which takes place at the capillary network of the donor and leads to a hylinosis with following obliteration of the vascular rete. Therefore the angiogenetic osteogenesis cannot develop. The clinical usuability of such material is discussed.

Prebycusis: physiological or pathological

A study was made on human temporal bones to elucidate the effects of aging on the auditory system. Ninety-six ears from 68 individuals, varying in age from infancy to 84 years, served as 'normal ears'. None of these cases had clinical or pathological evidence of specific ear diseases. 'Pathological ears' consisted of 89 ears from 58 individuals which exhibited slowly progressive hearing loss, and which had no specific known cause for the loss. Two aging phenomena were found to affect the human ear. The first is physiological, and has been called 'auditory senility'. It involves all the different parts of the auditory mechanism equally, and is responsible for the rise in auditory thresholds for the high frequencies, commonly seen in elderly people. The second phenomenon is pathological, and was termed 'auditory decay'. It involves only the perceptive system of the ear, and results in different types of clinical presentations, according to the morphological layer involved. Therefore, the recognition of two aging phenomena which affect the human ear may explain the reason for the wide variations in auditory acuity associated with old age.