Otosclerosis associated with Ménière's disease: a histological study

A histological study of a pair of temporal bones was performed in a case of Menière's disease. A severe endolymphatic hydrops and extensive capsular otosclerosis bilaterally was found. Severe endolympathic hydrops results from otosclerotic endolympahtic duct occlusion. Our unique histopathological findings show that a causal association exists between these two entities.

Measles virus and otosclerosis

Measles virus (MeV) might play an important role as an environmental stimulus in the etiopathogenesis of otosclerosis. Chronic inflammation was shown in morphologic investigations of otosclerotic foci and MeV N, P, and F proteins were detected within cells of the otosclerotic focus by immunohistochemical investigations. MeV RNA was extracted from fresh-frozen otosclerotic tissue by the use of in vitro RT-PCR. This result was validated through amplification of MeV genome sequences by RT-PCR from celloidin-embedded sections with morphologically ascertained otosclerotic foci. In searching for an immune response of the inner ear immune system against MeV proteins, elevated anti-MeV IgG levels were detected in the perilymph of patients with otosclerosis in comparison with the serum levels. In situ RT-PCR allowed the localization of MeV sequences in osteoclasts, osteoblasts, chondrocytes, macrophages, and epithelial cells in middle ear mucosa of otosclerotic tissue. Further evidence for MeV persistence has recently been given. Genotyping of MeV in otosclerotic foci demonstrated the presence of MeV genotype A, which circulated in Europe around 1960. All the above results confirm a strong association between MeV and otosclerosis.

Molecular biology of otosclerosis

Otosclerosis is a bone disease of the human otic capsule, which is among the most common causes of acquired hearing loss. The pathologic process is characterized by a wave of abnormal bone remodeling in specific sites of predilection within the endochondral layer of the temporal bone. Although the cause of otosclerosis remains uncertain, there is a clear genetic predisposition with half of all cases occurring in families with more than one affected member. There is also compelling evidence that measles virus may play a role in some cases. Ultimately, how genetic factors and viral infection result in otosclerosis must be explained by effects on the molecular factors that control bone remodeling.

Is there a relationship between myringosclerosis and atherosclerosis?

OBJECTIVE

Myringosclerosis and atherosclerosis are two different pathologies seen in different parts of the body. Both of these occur following a similar physiopathological process. However this has not previously been adequately discussed in the literature. Trauma to either the tympanic membrane or to the intimal layer of the arterial wall results in the formation of a sclerotic plaque. The goal of this study was to investigate the relationship between myringosclerosis and atherosclerosis.

PATIENTS

A total of 421 patients with the diagnosis of coronary artery disease were included in the study. All of the patients were evaluated for the presence of atherosclerosis by coronary angiography and for myringosclerosis by otoscopic examination.

MAIN OUTCOME MEASURES

The presence of myringosclerotic plaques, plaque dimensions and bilateral involvement of tympanic membranes were compared in the groups with and without atherosclerosis.

RESULTS

Amongst the 316 patients (75.0%) shown to have atherosclerosis, 65 (20.5%) also had myringosclerosis. Amongst the 105 patients without atherosclerosis, 24 (22.8%) had myringosclerosis. There was no statistically significant relationship between atherosclerosis and myringosclerosis (p > 0.05). Neither plaque dimensions nor bilateral involvement of the ears showed significant difference between the two groups (p >0.05 and p >0.05, respectively).

CONCLUSIONS

We conclude that there is no similar genetic tendency between atherosclerosis and myringosclerosis. The significance of the plaque dimensions and the bilateral involvement of tympanic membranes have not been satisfactorily discussed in the literature and this is the first time that they are being addressed. In contrast to the reported articles, there is no relationship between atherosclerosis and myringosclerosis other than being similar pathological processes occurring as a result of endothelial-epithelial damage.

Prevalence of histologic otosclerosis: an unbiased temporal bone study in Caucasians

BACKGROUND

'Histologic otosclerosis' refers to a disease process without clinical symptoms or manifestations that can only be discovered by sectioning of the temporal bone at autopsy. 'Clinical otosclerosis' concerns the presence of otosclerosis at a site where it causes conductive hearing loss by interfering with the motion of the stapes or of the round window membrane. Various authors have studied the prevalence of histologic otosclerosis on laboratory collections of temporal bones. Some 12-15% of the temporal bones with histologic otosclerosis have demonstrated stapedial fixation. Using these figures for calculating the prevalence of clinical otosclerosis gives an extrapolated clinical prevalence of 0.99-1.2%. This does not correlate well with the clinical data on otosclerotic families from which a clinical prevalence of 0.3% has been estimated.

OBJECTIVE

To study the prevalence of histologic otosclerosis in an unselected series of temporal bones.

STUDY DESIGN

During a 1-year period, 118 consecutive pairs of temporal bones of deceased patients at a tertiary center were collected to determine the prevalence of otosclerosis. Although histology remains the gold standard for evaluation of otosclerosis, the gross observation of temporal bone slices combined with microradiography was used to screen for otosclerotic lesions more rapidly and with a lower cost-benefit ratio. The temporal bones with suspected otosclerosis shown with these techniques were further analyzed by conventional histology.

RESULTS

2.5% of the 236 temporal bones (or 3.4% of patients) studied demonstrated histologic otosclerosis.

CONCLUSIONS

Although the prevalence of 2.5% is much lower than previously published figures on histologic otosclerosis, the extrapolated data (extrapolated clinical prevalence = 0.30-0.38%) correlate well with clinical studies of otosclerotic families. The previous studies based on laboratory collections were likely biased by the presence of hearing loss or other otological diseases.

Expression of collagens in the otosclerotic bone

The etiopathogenesis of otosclerosis is still controversially discussed. The major hypotheses discussed are a viral infection on a genetic background and an (autoimmune) collagen disease. The aim of our study was to investigate by immunohistochemistry the expression pattern of collagens within the otosclerotic focus. Stapes footplates from 30 patients with clinical otosclerosis undergoing stapedectomy were formalin fixed, decalcified and paraffin embedded. As controls, 30 autoptic temporal bone specimens were employed. We investigated the expression of collagens I-V with immunohistochemistry. The expression of collagen I showed a diffuse homogeneous distribution with increased staining of the otosclerotic focus. Collagen II was exclusively expressed in chondrocytes including the globuli interossei. The pattern of collagen III in the otosclerotic bone was web-like in contrast to a lamellar pattern in the control bone. The mucoperiosteal layer and connective tissue such as the vessels of the resorption lacunae expressed collagen IV. An increased expression of collagen V around osteocytes was observed in the otosclerotic focus. In conclusion, in the otosclerotic tissue, in comparison with the control bone, a high expression of collagen IV occurred. The immunohistochemical analysis of collagen II, which has been suggested to be implicated in the etiopathogenesis of otosclerosis, revealed no differences between control and otosclerotic bones. The intense staining of the otosclerotic focus with collagen I is in good agreement with an inflammatory process but in contrast with lesions like those in osteogenesis imperfecta.

Association Between Cupular Deposits and Otosclerosis

OBJECTIVE

To evaluate whether otosclerosis is an underlying mechanism for the production of cupular deposits and to study the association between cupular deposits and dysequilibrium in otosclerosis.

DESIGN

Retrospective human temporal bone (TB) study. The incidence of cupular deposits in these 70 TBs was analyzed. Correlations between cupular deposits and vestibular symptoms, endosteal involvement of the otosclerotic focus, stapedial fixation, and clinical history of stapes surgery were evaluated.

SETTING

Otolaryngology laboratory in a tertiary academic medical center.

PATIENTS

The study material consisted of 35 human TBs with otosclerosis and 35 age-matched controls.

MAIN OUTCOME MEASURES

Morphometric evaluations of the incidence of cupular deposits, endosteal involvement of the otosclerotic focus, and stapedial fixation were made by light microscopy. Clinical records were reviewed retrospectively for clinical history of stapes surgery and prevalence of vestibular symptoms. The incidence of cupular deposits was compared between the otosclerotic and control groups. Correlations between cupular deposits and vestibular symptoms, endosteal involvement of the otosclerotic focus, stapedial fixation, and clinical history of stapes surgery were evaluated in the subjects with otosclerosis.

RESULTS

The incidence of cupular deposits in TBs with otosclerosis was significantly higher than in those without whereas there was no correlation between the incidence of the deposits and dysequilibrium in cases of otosclerosis. An increase in deposits did not correlate with stapedial fixation, stapes surgery, or endosteal involvement.

CONCLUSIONS

Our results suggest otosclerosis as an underlying mechanism for the production of cupular deposits; however, we did not find an association between these deposits and vestibular symptoms.

Otosclerosis: etiopathogenesis and histopathology

Otosclerosis is a disease of the bony labyrinth manifesting clinically as a progressive conductive hearing loss, a mixed-type hearing loss, or a sensorineural hearing loss. The age of onset of the hearing loss caused by otosclerosis is principally between 15 and 40 years. Although histopathological inner ear changes due to otosclerosis have been very well documented, the true etiopathogenesis of the disease has yet to be described despite intensive research. Both genetic and environmental factors have been implicated, however.

Activated Osteoclasts with CD51/61 Expression in Otosclerosis

HYPOTHESIS

Stapes ankylosis is supposed to be a disease with variable histopathology caused by otosclerosis or pseudo-otosclerosis. Persistent measles virus infection of the otic capsule could induce reactivation of quiescent embryonic osteoclasts in otosclerosis.

BACKGROUND

Presence of measles virus RNA was demonstrated in the footplates of otosclerotic patients by reverse-transcription polymerase chain reaction (RT-PCR). Histology of active otosclerosis is featured by the presence of numerous osteoclasts with unknown phenotype.

METHODS

Nucleic acid was extracted from stapes footplates of clinically otosclerotic patients (n = 261). Genomic RNA of measles virus was amplified by RT-PCR. Amplification results were correlated to postoperative histologic and CD51/61 specific immunohistologic findings. A parallel alcalic phosphatase activity assessment was performed to evaluate the metabolic activity of osteoclasts in each section.

RESULTS

Among 261 stapes fixation cases, 175 otosclerotic stapes contained measles virus RNA. Histology for virus negative stapes (n = 86) represented nonotosclerotic, degenerative disorders. Histologically confirmed otosclerosis was featured by the presence of osteoclasts with renewed, embryonic phenotype. In otosclerosis, alcalic phosphatase activity was significantly higher compared with nonotosclerotic stapes ankylosis (P < .001).

CONCLUSION

The presence of CD51/61 positive osteoclasts in otosclerotic bone containing viral sequences provides the basis for an inflammatory bone remodeling disorder. Otosclerosis is a disease caused by persistent measles virus infection and reactivation of resting embryonic osteoclasts in the otic capsule.

[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.

Mondini-like malformation mimicking otosclerosis and superior semicircular canal dehiscence

In 2003, it was reported that superior semicircular canal dehiscence can mimic otosclerosis because of low-frequency bone conduction hearing gain and dissipation of air-conducted acoustic energy through the dehiscence. We report the case of a 17-year-old girl with left-sided combined hearing loss thought to be due to otosclerosis. Bone conduction thresholds were -10 dB at 250 and 500 Hz and she had a 40 dB air-bone gap at 250 Hz. When a tuning fork was placed at her ankle she heard it in her left ear. Acoustic reflexes and vestibular evoked myogenic potentials could be elicited bilaterally. Imaging of the temporal bones showed no otosclerosis, superior semicircular canal dehiscence or large vestibular aqueduct, but a left-sided, Mondini-like dysplasia of the cochlea with a modiolar deficiency could be seen. Mondini-like cochlear dysplasia should be added to the causes of inner-ear conductive hearing loss.

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.

Histologic otosclerosis is associated with the presence of measles virus in the stapes footplate

HYPOTHESIS

Persistent measles virus infection of the otic capsule is presumed to be one of the etiologic factors in otosclerosis. The viral pathogenesis of otosclerosis could be established only by correlative analysis: histologic examination of the stapes footplates and reverse-transcriptase polymerase chain reaction amplification of the viral RNA. At present, histologic analysis of the removed stapes footplates is the only appropriate method of distinguishing otosclerotic and nonotosclerotic stapes fixations.

BACKGROUND

The presence of measles virus was shown in otosclerotic patients by reverse-transcriptase polymerase chain reaction amplification of the viral RNA and detecting the viral proteins by immunohistochemistry.

METHODS

Nucleic acids (mRNA, vRNA, and DNA) were extracted from ankylotic stapes footplates of stapes fixation patients (n = 44). Measles virus genomic nucleoprotein RNA was amplified by seminested reverse-transcriptase polymerase chain reaction. Amplification results were correlated to postoperative histologic findings.

RESULTS

Measles virus RNA was detectable only in histologically otosclerotic stapes footplates (n = 32). Histology for virus-negative footplates (n = 12) excluded otosclerosis. Virus-negative stapes footplates showed annular calcification (n = 8), bone resorption with increased numbers of hemosiderophages (n = 2), and mononuclear cell infiltration with osteolysis (n = 2).

CONCLUSION

Stapes ankylosis is a heterogenous disease causing conductive hearing loss with different causes. Nonotosclerotic stapes fixations may belong to degenerative disorders with variable histopathology. Otosclerosis is an inflammatory disease resulting from persisting measles virus infection of the otic capsule.

[Congenital absence of the stapes suprastructure]

Congenital absence of the stapes suprastructure is an unusual anomaly, consequence of a developmental aberration involving partial absence of a derivate from the second branchial arch. Sometimes, exploratory tympanotomy may be the only mean of diagnosis when known conductive hearing loss is seen. This anomaly can appear isolated or associated to other major or minor anomalies. The treatment is surgical. We review the literature about the absence of the isolated stapes suprastructure.

[Dehiscence of the anterior semicircular canal and otosclerosis: a case report]

The dehiscence of the anterior semicircular canal is a new clinical entity, it is necessary to consider this when a gusher occurs during stapedial surgery.

CASE REPORT

We report a rare case of dehiscence of the anterior canal associated with otosclerosis. This was revealed by a gusher during the initial stapedectomy. At 3 months, an obliteration of the dehiscence was necessary by middle cranial fossa approach (persistant vestibular symptoms), seven months later. Revision stapedial surgery resulted in complete closure of the air-bone-gap.

CONCLUSION

High resolution CT scans of the temporal bone are the key to diagnosis. It is necessary to appreciate this pathology with advances in canal and vestibular surgery.

Influence of Hypercalcemia in the Formation of Tympanosclerosis in Rats

HYPOTHESIS

Hypercalcemia is thought to perform an important role in the etiopathogenesis of tympanosclerosis. The purpose of the present study was to assess the influence of hypercalcemia in the development of tympanosclerosis in rats with or without acute otitis media.

BACKGROUND

The pathogenesis of tympanosclerosis is still unclear. Histologically, it is characterized by a hyaline degeneration in the lamina propria of the middle ear and mastoid mucosa and may lead to a calcification process. The process of calcification is similar to that of other pathologically calcified tissues, such as vessels, heart valves, cornea, and others, which depend on calcium serum levels.

METHODS

Twenty-four Wistar rats were divided into two different groups, with one group submitted to hypercalcemia status through calcium diet supplementation and the other used as a control group (normal calcium content diet). Both were submitted to induction of tympanosclerosis by inoculation of Streptococcus pneumoniae on the right middle ear only. Otomicroscopy was conducted every 15 days, and after 7 weeks of inoculation, the animals were killed and the tympanic bullae were resected to be analyzed through light and electron microscopy.

RESULTS

The group submitted to hypercalcemia presented a prevalence of tympanosclerosis of 25% against 16.7% in the control group, presenting a relative risk of 1.27 (p=0.72).

CONCLUSION

The results suggest that hypercalcemia can have an influence in the development of tympanosclerosis.

[Far-advanced otosclerosis]

OBJECTIVES

The aim of this study was to report a series of patients with far-advanced otosclerosis who were unable to benefit from hearing aids. Among patients with profound hearing loss, it is particularly useful to diagnose far-advanced otosclerosis even if relatively rare, because stapes surgery can improve hearing to a level allowing conventional hearing aid use (sometime the only choice before cochlear implant).

MATERIAL AND METHODS

We retrospectively reviewed the charts of 7 patients (9 operated ears) in order to highlight diagnostic criteria, surgical indications and results of stapes surgery (stapedectomy or stapedotomy).

RESULTS

Diagnosis of far-advanced otosclerosis was based on clinical presentation, course of hearing loss, positive family history of otosclerosis, and results of CT scan which was helpful in all the cases. Obliterative otosclerosis was found in 55% of the cases. Success of stapes surgery was observed in 89%, with no significant difference between stapedectomy or stapedotomy.

CONCLUSION

Although rare, far-advanced otosclerosis must be diagnosed because patients can benefit from stapes surgery (and subsequently fitting of appropriate hearing aids).

Two Subgroups of Stapes Fixation: Otosclerosis and Pseudo-Otosclerosis

HYPOTHESIS

Stapes ankylosis is a disease with variable histopathology and can be caused by otosclerosis or pseudo-otosclerosis. Viral pathogenesis of otosclerosis could be established only by correlative analysis: histologic examination of the stapes footplate and reverse-transcriptase polymerase chain reaction (RT-PCR) amplification of the viral RNA.

BACKGROUND

Presence of the RNA genome of measles virus was demonstrated in the footplates of clinically otosclerotic patients by RT-PCR, and also viral proteins were detected by immunohistochemistry.

METHODS

Nucleic acids were extracted from ankylotic stapes footplates of clinically stapes fixation patients (n = 104). Measles virus genomic nucleoprotein (NP) RNA was amplified by seminested RT-PCR. Amplification results were correlated to postoperative histologic and audiologic findings.

RESULTS

Measles virus RNA was detectable only in histologically otosclerotic stapes footplates (n = 67). Histology for virus negative footplates (n = 37) excluded otosclerosis. Virus negative stapes footplates showed nonotosclerotic, degenerative disorders.

CONCLUSIONS

Stapes ankylosis is a heterogeneous disease causing conductive hearing loss with different etiologies. Nonotosclerotic stapes fixations could be established as pseudo-otosclerosis and may belong to nonspecific, degenerative disorders with variable and noncharacteristic histopathology. Otosclerosis is an inflammatory disease caused by persisting measles virus infection of the otic capsule.

Ultrastructural Analysis of the Chorda Tympani Nerve in Chronic Suppurative Otitis Media

OBJECTIVE

To compare ultrastructure of the chorda tympani nerve by light and electron microscopy in patients with otosclerosis and chronic suppurative otitis media.

STUDY DESIGN

Comparative prospective study.

SETTING

Tertiary care, referral medical center.

PATIENTS

The tympanic segments of chorda tympani nerves were collected for ultrastructural investigation in 20 cases with chronic suppurative otitis media and 10 cases with otosclerosis that underwent middle ear surgery.

RESULTS

Histopathologic examinations of the suppurative group showed that unmyelinated fibers were almost totally lost and replaced by collagen fibers. The thickness of the myelin sheaths was very slender, whereas some of them were atrophic. A substantial increase was encountered in the endoneural collagen substance and connective tissue, whereas inflammatory elements and edema were present occasionally. Degenerative alterations of the myelinated fibers mainly occurred in the form of adaxonal vacuoles. There was disorganization and separation of parallel lamellae of Schmidt-Lanterman clefts.

CONCLUSION

The chorda tympani nerve should be preserved in otologic surgery. However, inadvertent dissection of the chorda tympani nerve in chronic suppurative otitis media surgery will not possibly cause a postoperative disturbance in light of ultrastructural changes that occur in the nerve.

Fixation of the Stapes Footplate in Children: A Clinical and Temporal Bone Histopathologic Study

OBJECTIVE

To clarify the anatomic characteristics, cause, and surgical outcomes relating to fixation of the stapes footplate in children.

STUDY DESIGN

Retrospective case review and four-center histopathologic study of temporal bones.

SETTING

Tertiary referral center.

PATIENTS

We reviewed charts and histologic specimens from 12 children, aged 7 to 13 years, who underwent surgery for footplate fixation. We also studied stapes footplates in 288 temporal bones from 181 children ranging from newborn (20-44 weeks of gestation) to 13 years of age.

MAIN OUTCOME MEASURE

Anomalies of the stapes footplate in children.

RESULTS

The average age of diagnosis of hearing loss was 6.6 years. Criteria for a diagnosis of otosclerosis were progression of a conductive hearing loss and an intraoperative finding of fixation of the anterior stapediovestibular joint in five patients. In contrast, a nonhomogeneous, thickened, fixed footplate and the absence of an annular ligament were indicators of congenital fixation in six children. In one child, there was neither new bone from the otic capsule nor any obvious otosclerotic foci. In the temporal bone study, 17 of 181 (9.4%) children had anomalies of the stapes footplates, with ankylosis in 4 (2.2%). In two subjects (1.1%), there was an otosclerotic focus not in contact with the stapes footplate.

CONCLUSION

Children younger than 6 years with various congenital anomalies are more likely to have congenital footplate fixation, which will present intraoperatively as a thickened footplate with a partial or absent annular ligament. Children older than 6 years with progressive conductive hearing loss are more likely to have otosclerosis, which presents as fixation of the anterior stapediovestibular joint. The difference in surgical outcomes is probably related to different degrees of footplate abnormality.

[Is imaging possible for otosclerosis? Characteristics of the disease and a survey of the clinical relevance of imaging]

Otosclerosis is a localized progressive disease of bone remodeling within the otic capsule of the human temporal bone. Histomorphologically, active cochlea otosclerosis (otospongiosis) is diagnosed in the presence of foci of demineralization in the otic capsule. The clinical symptoms of otosclerosis are associated with mixed and sensorineural hearing loss. With recent technological advances, diagnostic imaging of the inner ear is becoming more and more important in the evaluation of diseases affecting the cochlea. Studies could demonstrate that otosclerosis has a characteristic appearance on high-resolution computed tomography (HRCT), producing a distinctive pericochlear hypodense double ring. Its appearance on MRI is not as readily appreciated, producing a ring of intermediate signals in the pericochlear and perilabyrinthine regions on T1-weighted images, demonstrating mild to moderate enhancement after gadolinium administration. The ethiology and pathophysiology of otosclerosis are described and a review of the literature is given to illustrate the clinical relevance of imaging in otosclerosis.

Quantification of Angiogenesis in Otosclerosis

OBJECTIVES/HYPOTHESIS

The determinants of clinical versus histologic otosclerosis are unknown, but angiogenesis is associated with active disease. We hypothesized that quantification of angiogenesis in otosclerotic human temporal bones could reveal significant differences between clinical and histologic cases.

STUDY DESIGN

We reviewed all otosclerosis specimens meeting criteria from the temporal bone collection of the Massachusetts Eye and Ear Infirmary and 10 normal controls.

METHODS

Digital images were taken at predilection sites, followed by computer-assisted analysis. Canalicular area (CA), the aggregate of vascular spaces within bone, microvessel density (MVD), area, and depth were the main measures. Evidence of a direct connection between local vessels and the vasculature of the otosclerotic focus was also recorded for each specimen.

RESULTS

The average area (mm) and depth (number of sections containing otosclerosis) of clinical lesions was significantly greater than histologic lesions. Total microvessel counts were significantly greater in clinical versus histologic lesions, and both clinical and histologic lesions contained significantly greater numbers of microvessels than the normal otic capsule. CA was also significantly higher in clinical lesions. MVD was slightly but not significantly higher in clinical lesions. Importantly, a direct connection between named vessels and the otosclerotic vasculature was significantly more frequent in clinical lesions.

CONCLUSIONS

Computer-assisted quantification revealed significantly greater measures of angiogenesis in clinical versus histologic otosclerosis. Direct connection to adjacent vessels may support angiogenesis in this disease. Sustained angiogenesis may be an important determinant of clinical otosclerosis.