Middle Ear Ossicular Joint Changes in Type 2 Diabetes Mellitus: A Histopathological Study

OBJECTIVES

Although previous research has indicated inner ear changes in diabetes mellitus (DM) patients, no prior study has explored the middle ear, particularly the ossicles and their joints, in DM patients. This study aimed to investigate whether type 2 DM is associated with middle ear changes, specifically affecting the ossicular chain and joints.

METHODS

This study included 47 ears from 25 patients with DM (male = 13, female = 12, age: 51.0 ± 20.5) and age- and sex-matched controls (male = 10, female = 10, age: 54.8 ± 15.9) (sex; p = 1.000, Age; p = 0.991). Otopathological evaluations of the auditory ossicles and incudomalleolar joint (IMJ) were performed using light microscopy.

RESULTS

In the IMJ of DM cases, malleus hyalinized cartilage (Malleus hC) and incus hyalinized cartilage (Incus hC) were significantly increased compared with control cases (Malleus hC; DM, 34.17 ± 9.71 μm vs. control 21.96 ± 4.16 μm, p < 0.001) (Incus hC; DM 35.11 ± 10.12 μm vs. control 22.42 ± 4.368 μm, p < 0.001). In addition, bone-line distance was significantly longer than in DM cases than control cases (DM 266.72 ± 59.11 μm vs. control 239.81 ± 35.56 μm p = 0.040). On the other hand, joint discus distance was longer in the control group than in DM cases (DM 96.84 ± 36.80 μm vs. Control 113.63 ± 23.81 μm, p = 0.001).

CONCLUSIONS

This study reveals a notable increase in the hyalinized cartilage layer and bone-line distance accompanied by reducing joint discus distance within the IMJ in DM cases. These findings suggest that DM may influence microjoints, such as the IMJ, and potentially impact auditory function.

EVIDENCE LEVEL

N/A Laryngoscope, 134:2871-2878, 2024.

Cochlear Otosclerosis and Secondary Hydrops (Ménière's Syndrome)

ABSTRACT

This article discusses a case of cochlear otosclerosis leading to secondary hydrops and near-complete hearing loss. Histopathological examination revealed advanced multifocal otosclerosis in both temporal bones, with specific focus on cochlear invasion and significant bone resorption. The severity of the case ruled out surgical intervention due to the risk of further hearing loss. The article emphasizes the challenges in managing otosclerosis-related hydrops and highlights the potential use of advanced imaging techniques for diagnosis. The study underscores the complexity of otosclerosis-induced hearing loss, contributing to the understanding of this pathology and its impact on auditory function.

The role of motor proteins in photoreceptor protein transport and visual function

BACKGROUND

Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, wherein the perception of vision is initiated when these neurons respond to photons in the light stimuli. The photoreceptor cell is structurally studied as outer segments (OS) and inner segments (IS) where proper protein sorting, localization, and compartmentalization are critical for phototransduction, visual function, and survival. In human retinal diseases, improper protein transport to the OS or mislocalization of proteins to the IS and other cellular compartments could lead to impaired visual responses and photoreceptor cell degeneration that ultimately cause loss of visual function.

RESULTS

Therefore, studying and identifying mechanisms involved in facilitating and maintaining proper protein transport in photoreceptor cells would help our understanding of pathologies involving retinal cell degeneration in inherited retinal dystrophies, age-related macular degeneration, and Usher Syndrome.

CONCLUSIONS

Our mini-review will discuss mechanisms of protein transport within photoreceptors and introduce a novel role for an unconventional motor protein, MYO1C, in actin-based motor transport of the visual chromophore Rhodopsin to the OS, in support of phototransduction and visual function.

Diversity of the cochlear and vestibular pathologies in human temporal bones of newborns infected with cytomegalovirus

Hypothesis

Human temporal bones of newborns with congenital cytomegalovirus (cCMV) infection can be characterized by diverse cochlear and vestibular histopathologies associated with the variability in sensorineural hearing loss (SNHL) and vestibular dysfunction in these newborns.

Background

Only a small number of studies on the cochlear and vestibular pathologies in human temporal bones with cCMV infection have been previously reported.

Methods

Cochleovestibular histopathologies were evaluated in 4 temporal bones from 3 infants with cCMV infection by light microscopy.

Results

In one available temporal bone of the infant in Case 1, no cytomegalic cells were found. Large areas of cellular and non-cellular structures were observed in the scala tympani of the perilymphatic space; however, there was no obvious loss of cochlear or vestibular hair cells. In Case 2, cytomegalic cells, a loss of vestibular hair cells, and a loss of nerve fibers were observed only in the area of dark cells in the vestibular labyrinth of the left temporal bone. No cytomegalic cells were found in the right temporal bone of the same infant; however, there was a loss of outer hair cells in the organ of Corti and hypervascularity in the stria vascularis. The one available temporal bone of the infant in Case 3 showed cytomegalic cells and a loss of hair cells in both cochlear and vestibular parts of the inner ear.

Conclusions

Human temporal bones of newborns with cCMV demonstrate diverse cochleovestibular histopathologies. This diversity is consistent with the variable SNHL and vestibular dysfunction reported in infected newborns.

Otopathologic Abnormalities in CHARGE Syndrome

OBJECTIVE

To perform an otopathologic analysis of temporal bones (TBs) with CHARGE syndrome.

STUDY DESIGN

Otopathologic study of human TB specimens.

SETTING

Otopathology laboratories.

METHODS

From the otopathology laboratories at the University of Minnesota and Massachusetts Eye and Ear Infirmary, we selected TBs from donors with CHARGE syndrome. These TBs were serially sectioned at a thickness of 20 µm, and every 10th section was stained with hematoxylin and eosin. We performed otopathologic analyses of the external ear, middle ear (middle ear cleft, mucosal lining, ossicles, mastoid, and facial nerve), and inner ear (cochlea, vestibule, internal auditory canal, and cochlear and vestibular nerves). The gathered data were statistically analyzed.

RESULTS

Our study included 12 TBs from 6 donors. We found a high prevalence of abnormalities affecting the ears. The most frequent findings were stapes malformation (100%), aberrant course of the facial nerve (100%) with narrow facial recess (50%), sclerotic and hypodeveloped mastoids (50%), cochlear (100%) and vestibular (83.3%) hypoplasia with aplasia of the semicircular canals, hypoplasia and aplasia of the cochlear (66.6%) and vestibular (91.6%) nerves, and narrowing of the bony canal of the cochlear nerve (66.6%). The number of spiral ganglion and Scarpa's ganglion neurons were decreased in all specimens (versus normative data).

CONCLUSIONS

In our study, CHARGE syndrome was associated with multiple TB abnormalities that may severely affect audiovestibular function and rehabilitation.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

Quantitative assessment of cochlear and vestibular ganglion neurons in temporal bones with chronic otitis media

PURPOSE

In this study, we aimed to determine whether or not COM leads to loss of spiral and Scarpa ganglion neurons.

METHODS

From the human temporal bone (HTB) collection at the University of Minnesota we selected human temporal bones with COM, defined as the presence of clinically intractable tissue abnormalities in the middle ear (cholesteatoma, perforation of the eardrum, granulation tissue, fibrosis, tympanosclerosis, and cholesterol granuloma). We also selected HTBs from donors with no ear diseases as controls. We quantitatively analyzed the number of spiral and Scarpa ganglion cells and compared the results obtained in the control and study groups.

RESULTS

In both COM and control groups we observed a significant negative correlation between age and number of both spiral (R = -0.632; P < 0.001; 95% CI - 0.766 to - 0.434) and Scarpa ganglion (R = - 0.404; P = 0.008; 95% CI - 0.636 to - 0.051) cells. We did not find any significant differences in the number of spiral ganglion cells (in total or per segment) or in the density of Scarpa ganglion cells (in each vestibular nerve or both) in the COM group as compared with controls (P > 0.05).

CONCLUSIONS AND RELEVANCE

Our results did not demonstrate significant loss of cochlear or vestibular peripheral ganglion neuron loss in HTBs with COM as compared with controls.

Cochlear turns measurements in patients with meningitis: A histopathological study

OBJECTIVE

To demonstrate the cochlear turns area changes among patients with a history of meningitis, through otopatologic study.

METHODS

We performed an analysis of the area of the bony cochlear turns and the cochlear lumen of the horizontal sections containing the modiolus and the area of the basal turn at the level of round window, in temporal bones obtained from patients with a history of meningitis and compared to a nondiseased control group.

RESULTS

The mean area of the bony walls and the lumen of all cochlear turns are reduced within the meningitis group. Patients who presented a time from the diagnosis of meningitis to death longer than 30 days had a significant reduction in the cochlear turns area, as compared to the control group.

CONCLUSION

Future studies may further correlate audiologic outcomes, cochlear volume, and cochlear area among patients with meningitis.

Cytomegalovirus-induced pathology in human temporal bones with congenital and acquired infection

OBJECTIVE

Publications on histopathology of human temporal bones with cytomegalovirus (CMV) infection are limited. We aim to determine histopathology of the inner ears and the middle ears in human temporal bones with congenital and acquired CMV infections.

METHODS

Temporal bones from 2 infants with congenital and 2 adults with acquired CMV infection were evaluated by light microscopy.

RESULTS

Two infants with congenital CMV infection showed striking pathological changes in the inner ear. There was a hypervascularization of the stria vascularis in the cochlea of the first infant, but no obvious loss of outer and inner hair cells was seen in the organ of Corti. However, cytomegalic cells and a loss of outer hair cells were found in the cochlea of the second infant. The vestibular organs of both infants showed cytomegalic cells, mostly located on dark cells. There was a loss of type I and type II hair cells in the macula of the saccule and utricle. Loss of hair cells and degeneration of nerve fibers was also seen in the semicircular canals. Both infants with congenital infection showed abundant inflammatory cells and fibrous structures in the middle ear cavity. No evidence of cytomegalic cells and hair cell loss was found in the cochlea or vestibular labyrinth in acquired CMV infection.

CONCLUSIONS

In two infants with congenital CMV infection, the cochlea, vestibule, and middle ear were highly affected. Temporal bones of adult donors with acquired viral infection showed histological findings similar to donors of the same age without ear disease.

Histopathology of Inner Ear Malformations: Potential Pitfalls for Cochlear Implantation

HYPOTHESIS

The presence of bony inner ear malformations may associate with a number of anatomical abnormalities affecting the middle ear structures. Those malformations may create pitfalls and complications for cochlear implantation.

BACKGROUND

Inner ear malformations associate with varying degrees of hearing loss, and frequently require cochlear implantation for hearing rehabilitation. Therefore, the abnormalities affecting the middle- and inner-ear structures may increase the risk of surgical complications.

METHODS

We examined 38 human temporal bones from donors with bony inner ear malformations. Using light microscopy, we analyzed the presence of abnormalities in the structures of the middle- and inner-ear.

RESULTS

Our collection comprises of 38 specimens with inner-ear malformations (cochlear aplasia, n = 3; cochlear hypoplasia, n = 30; incomplete partition, n = 3; isolated vestibular malformation, n = 2). The anatomy of the middle ear was abnormal in most temporal bones with cochlear aplasia, cochlear hypoplasia, and incomplete partition type I (40%-100%). Some of those abnormalities (hypoplastic or obliterated mastoid, 55.2%; aplastic or obliterated round window, 71.0%; aberrant course of the facial nerve, 36.8%) may hinder the access to the round window using the conventional facial recess approach for cochlear implantation. The cochlear nerve and associated bony structures (internal auditory canal and bony canal for cochlear nerve) were normal in 71.0% of all temporal bones with inner ear malformations.

CONCLUSION

Each different type of malformation may create specific surgical challenges to surgeons. Comprehensive preoperative imaging is fundamental toward the surgical success of cochlear implants in patients with malformations. Alternatives to circumvent those middle- and inner-ear abnormalities and potential complications are further discussed.

Cochleosaccular (Scheibe) dysplasia in dogs: A temporal bone study

The objective of this study was to evaluate any otopathologic changes in temporal bone specimens from dogs with deafness related to cochleosaccular (Scheibe) dysplasia (CSD). We used the canine temporal bone collections of the Otopathology Laboratory at the University of Minnesota and of the Massachusetts Eye and Ear Infirmary at Harvard University in Boston. Our morphometric analysis included measuring the areas of the stria vascularis and the spiral ligament and counting the number of spiral ganglion cells. In addition, we noted the presence of the organ of Corti and cochlear hair cells, assessed the location of Reissner's membrane and the saccular membrane, and counted the number of both Type I and Type II vestibular hair cells in the macule of the saccule and vestibular ganglion cells. In the group of specimens from dogs with cochleosaccular dysplasia, we observed generalized degeneration in the cochlea and a significantly decreased number of Type I and Type II vestibular hair cells and vestibular ganglion cells. As hereditary deafness is presently untreatable with known therapeutic methods, dogs with cochleosaccular dysplasia should not be considered for breeding. Future therapeutic approaches, such as stem cell therapies, should be designed to target all the elements of the cochlea in addition to the saccule as it was found that both are affected in dogs with CSD.

Quantitative assessment of vestibular otopathology in granulomatosis with polyangitis: A temporal bone study

Objective

To investigate the temporal bone histopathology of vasculitis, especially in the vestibular organs, in granulomatosis with polyangitis (GPA).

Methods

Using light and differential interference contrast microscopy, we examined 12 human temporal bones from six deceased GPA patients and 12 histopathologically normal human temporal bones from six deceased age‐matched patients.

Results

In the GPA group, three patients had undergone tympanostomy tube placement. Two of them had suffered mixed hearing loss; one, sensorineural hearing loss; and one, conductive hearing loss. Of the 12 specimens in the GPA group, the granulation tissue invaded the round window niche in seven; cochlear hair cells were not preserved in five. Hemosiderin was deposited in the stria vascularis in eight specimens, in the ampulla or semicircular duct in 10, and in the vestibule in three. The spiral ligament showed severe loss of cellularity in two specimens. In the GPA group, type I vestibular hair cell density was significantly decreased; however, type II vestibular hair cell density did not significantly differ between the GPA group and the control group.

Conclusion

Our histopathologic findings in human temporal bone specimens of GPA patients delineated changes in the tympanic membrane, middle ear cavity, round window membrane, organ of Corti, stria vascularis, spiral ligament, ampulla, semicircular duct, and vestibule. Type I vestibular hair cell density significantly decreased in the GPA group, as compared with the control group.

Level of Evidence

N/A

Bilateral Glomus Tympanicum Tumors: Human Temporalbone Study

To describe human temporal bones with bilateral glomus tympanicum tumors. Patient is 83-year-old black female who no pulsatile tinnitus. The histopathologic characteristics of human temporal bones after death were setting Department of Otolaryngology of University of Minnesota in USA. Histopathologic observation of temporal bones showed bilateral small glomus tympanicum tumors limited to the promontory. Although there was bilateral tinnitus, there was no pulsatile tinnitus, no conductive hearing loss and both of the tympanic membranes were intact. Histopathologic observation of temporal bones after death showed bilateral glomus tympanicum tumors. To our knowledge, this is the first reported case of bilateral glomus tympanicum tumors.

The aetiopathologies of Ménière's disease: a contemporary review

Ménière's disease, a condition first described in the 1800's, has been an advancing area of clinical interest and scientific research in recent decades. Guidelines published by the American Academy of Otolaryngology - Head and Neck Surgery remained nearly static for almost 20 years, although we have certainly expanded our knowledge of the aetiology of the disease since that time. This review of the literature highlights the breadth and detail of the current theories in understanding the pathophysiology of this enigmatic disease. Histopathological specimens providing evidence of many of the aetiologies are presented as well. We aim to provide a centralised and updated resource regarding current and emerging theories for Ménière's disease.

Role of Macrophage Migration Inhibitory Factor in Paranasal Sinus Mucocele

Background

Little is known about the immunologic aspects and the pathogenesis of the paranasal sinus mucocele.

Methods

The fluids of paranasal sinus mucoceles were obtained from 12 subjects. The concentration of macrophage migration inhibitory factor (MIF), interleukin 1β, tumor necrosis factor a, and regulated on activation normal T cell expressed and secreted (RANTES) were determined by enzyme-linked immunosorbent assay, and the levels of endotoxin were detected with kinetic Turbidimetric Assay.

Results

MIF and endotoxin were detected in the fluid of all samples, whereas interleukin-1β and RANTES were detected in 1 and 3 subjects out of 12 samples. Tumor necrosis factor a was not detected in any of the samples. A significant positive correlation between the levels of MIF and the period with symptoms such as pain, swelling of face, and visual disturbance was observed.

Conclusion

These findings suggest that MIF and endotoxin may play an important role in the pathogenesis of paranasal sinus mucocele. MIF may be an important factor causing the development and exacerbation of the disease.

Neutrophil Extracellular Traps and Fibrin in Otitis Media: Analysis of Human and Chinchilla Temporal Bones

Background

Bacterial resistance in acute otitis can result in bacterial persistence and biofilm formation, triggering chronic and recurrent infections.

Objective

To investigate the middle ear inflammatory response to bacterial infection in human and chinchilla temporal bones.

Design, Setting, and Participants

Six chinchillas underwent intrabullar inoculations with 0.5 mL of 106 colony-forming units (CFUs) of Streptococcus pneumoniae, serotype 2. Two days later, we counted bacteria in middle ear effusions postmortem. One ear from each chinchilla was processed in paraffin and sectioned at 5 µm. The opposite ear was embedded in epoxy resin, sectioned at a thickness of 1 µm, and stained with toluidine blue. In addition, we examined human temporal bones from 2 deceased donors with clinical histories of otitis media (1 with acute onset otitis media, 1 with recurrent infection). Temporal bones had been previously removed at autopsy, processed, embedded in celloidin, and cut at a thickness of 20 µm. Sections of temporal bones from both chinchillas and humans were stained with hematoxylin-eosin and immunolabeled with antifibrin and antihistone H4 antibodies.

Main Outcome Measures

Histopatological and imminohistochemical changes owing to otitis media.

Results

Bacterial counts in chinchilla middle ear effusions 2 days after inoculation were approximately 2 logs above initial inoculum counts. Both human and chinchilla middle ear effusions contained bacteria embedded in a fibrous matrix. Some fibers in the matrix showed positive staining with antifibrin antibody, others with antihistone H4 antibody.

Conclusions and Relevance

In acute and recurrent otitis media, fibrin and neutrophil extracellular traps (NETs) are part of the host inflammatory response to bacterial infection. In the early stages of otitis media the host defense system uses fibrin to entrap bacteria, and NETs function to eliminate bacteria. In chronic otitis media, fibrin and NETs appear to persist.

Evidence against the mucosal traction theory in cholesteatoma

OBJECTIVES

To investigate the distribution of ciliated epithelium in the human middle ear and its potential role in the formation of cholesteatoma.

STUDY DESIGN

Comparative human temporal bone study.

METHODS

We selected temporal bones from 14 donors with a diagnosis of cholesteatoma, 15 with chronic otitis media without retraction pockets, 14 with chronic otitis media with retraction pockets, 14 with cystic fibrosis (CF), and 16 controls. We mapped the distribution of the ciliated cells in the mucosal lining of the middle ear and tympanic membrane using three-dimensional reconstruction analysis, and counted the number of ciliated cells in the middle ear mucosa.

RESULTS

Ciliated cells are extremely sparse in the epithelial lining of the lateral surface of the ossicles in the epitympanum and the medial surface of the tympanic membrane. Furthermore, there is a significant decrease in the number of ciliated cells in these areas in temporal bones with cholesteatoma, chronic otitis media, chronic otitis media with retraction pockets, and CF compared to controls. Ciliated cells most commonly are located at the hypotympanum and the Eustachian tube opening but not the tympanic membrane or epitympanum.

CONCLUSION

The paucity of ciliated epithelial cells on the medial side of the tympanic membrane and the lateral surface of the ossicles in the epitympanum in cases with cholesteatoma and/or chronic otitis media do not support the mucosal migration theory of cholesteatoma formation.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:1663-1667, 2018.

Does Otosclerosis Affect Dark and Transitional Cells in the Human Vestibular Labyrinth?

HYPOTHESIS

The density of vestibular dark cells (DCs) and vestibular transitional cells (TCs) can be quantitatively decreased in human temporal bones with otosclerosis.

BACKGROUND

Previous reports have shown that otosclerosis can lead to vestibular symptoms.

METHODS

We examined 61 human temporal bone specimens from 52 deceased donors with otosclerosis group-with and without endosteal involvement (EI), and with and without endolymphatic hydrops (EH)-versus 25 specimens from 18 age-matched controls. Using light microscopy, we evaluated the nonsensory epithelium of the lateral semicircular canal (LSC) and posterior semicircular canal (PSC) of the human vestibular labyrinth, focusing on the density of DCs and TCs.

RESULTS

In both the LSC and the PSC, as compared with the control group, the mean density of DCs significantly decreased in the EI (+) group, in the EI (+) and EH (+) subgroup, and in the EI (+) and EH (-) subgroup (p < 0.05). In addition, we found a significant difference in the mean density of DCs between the EI (+) group and the EI (-) group in the LSC and in the PSC (p < 0.05). But we found no significant difference in the mean density of TCs in any of the otosclerosis groups or subgroups as compared with the control group (p > 0.05).

CONCLUSION

We found a decrease in the density of DCs associated with EI in human temporal bone specimens with otosclerosis, regardless of the presence of EH. This decrease might cause damage in ion and water transportation, leading to vestibular symptoms.

Secondary Endolymphatic Hydrops

HYPOTHESIS

A review of the most recent literature will provide clinicians with an update of secondary endolymphatic hydrops, aiding in diagnosis and treatment of affected patients.

BACKGROUND

Secondary endolymphatic hydrops is a pathologic finding of the inner ear resulting in episodic vertigo and intermittent hearing loss. It is a finding for which extensive research is being performed.

METHODS

A review of the most recent literature on secondary endolymphatic hydrops was performed using PubMed literature search.

RESULTS

Recent investigation of secondary endolymphatic hydrops has brought attention to traumatic and inflammatory insults as causes for secondary endolymphatic hydrops. Such etiologies, including postsurgical effects of cochlear implantation and endolymphatic sac ablation; otosclerosis and its operative intervention(s); acoustic and mechanical trauma; medications; and systemic inflammatory processes, have been determined as causes of secondary lymphatic hydrops. Histopathological slides for many of the etiologies of secondary endolymphatic hydrops are presented.

CONCLUSION

Through an understanding of the pathophysiology and etiologies of secondary endolymphatic hydrops, clinicians will gain a better understanding of this complex disease process, which will aid in treatment of patients with this disease process.

Progression of changes in the sensorial elements of the cochlear and peripheral vestibular systems: The otitis media continuum

Our study aimed to evaluate pathologic changes in the cochlear (inner and outer hair cells and stria vascularis) and vestibular (vestibular hair cells, dark, and transitional cells) sensorial elements in temporal bones from donors who had otitis media. We studied 40 temporal bones from such donors, which were categorized in serous otitis media (SOM), serous-purulent otitis media (SPOM), mucoid/mucoid-purulent otitis media (MOM/MPOM), and chronic otitis media (COM); control group comprised 10 nondiseased temporal bones. We found significant loss of inner and outer cochlear hair cells in the basal turn of the SPOM, MOM/MPOM and COM groups; significant loss of vestibular hair cells was observed in the MOM/MPOM and COM groups. All otitis media groups had smaller mean area of the stria vascularis in the basal turn of the cochlea when compared to controls. In conclusion, our study demonstrated more severe pathologic changes in the later stages of the continuum of otitis media (MOM/MPOM and COM). Those changes seem to progress from the basal turn of the cochlea (stria vascularis, then inner and outer hair cells) to the middle turn of the cochlea and to the saccule and utricle in the MOM/MPOM and COM stages.

Histopathologic Changes of Human Vestibular Epithelia in Intralabyrinthine Hemorrhage

Objective:

To determine whether intralabyrinthine hemorrhage affects vestibular hair cells, dark cells, and transitional cells in human temporal bones.

Methods:

We examined 9 temporal bone specimens from 9 deceased donors with unilateral intralabyrinthine hemorrhage (the hemorrhage group) along with their 9 contralateral temporal bone specimens without hemorrhage (the control group). We estimated the density of type I and type II hair cells in all peripheral sensorial organs (including the cristae of the superior, lateral, and posterior semicircular canals, as well as the maculae of the saccule and utricle). We also estimated the density of dark and transitional cells in the lateral and posterior semicircular canals.

Results:

The loss of type I hair cells in the cristae of the superior, lateral, and posterior semicircular canals and in the maculae of the saccule and utricle was significantly higher in the hemorrhage group, as compared with the control group ( P < .05). The density of type II hair cells in the cristae of the superior and posterior canals and in the macula of the saccule significantly differed between the hemorrhage group and the control group ( P < .05).

Conclusion:

The loss of vestibular hair cells might be the cause of vestibular symptoms in patients with intralabyrinthine hemorrhage.

Deterioration of Vestibular Cells in Labyrinthitis

OBJECTIVE

To quantitatively assess the effect of serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans on vestibular hair cells, dark cells, and transitional cells.

METHODS

We examined human temporal bone specimens with serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans, then compared them with age-matched control groups without labyrinthitis. We evaluated the density of type I and II vestibular hair cells, dark cells, and transitional cells in the peripheral sensorial organs.

RESULTS

The mean density of type I vestibular hair cells in the maculae of the saccule significantly differed between the serous labyrinthitis group and its control group. The loss of type I and II vestibular hair cells in all of the peripheral sensorial organs was significantly higher in the suppurative labyrinthitis group than in its control group. The mean density of dark cells in the lateral and posterior semicircular canals was significantly lower in the suppurative labyrinthitis group than in its control group. The mean density of type I and II vestibular hair cells, dark cells, and transitional cells was significantly lower in the labyrinthitis ossificans group than in its control group.

CONCLUSION

The loss of vestibular hair cells and degenerative changes in dark cells and transitional cells could affect vestibular function in patients with labyrinthitis.

A 3-D analysis of the protympanum in human temporal bones with chronic ear disease

Eustachian tube dysfunction is believed to be an important factor to cholesteatoma development and recurrence of disease after surgical treatment. Although many studies have described prognostic factors, evaluation methods, or surgical techniques for Eustachian tube dysfunction, they relied on the soft tissues of its structure; little is known about its bony structure-the protympanum-which connects the Eustachian tube to the tympanic cavity, and can also be affected by several inflammatory conditions, both from the middle ear or from the nasopharynx. We studied temporal bones from patients with cholesteatoma, chronic otitis media (with and without retraction pockets), purulent otitis media, and non-diseased ears, looking for differences between the volume of the protympanum, the diameter of the Eustachian tube isthmus, and the distance between the anterior tympanic annulus and the promontory. Light microscopy and 3-D reconstruction software were used for the measurements. We observed a decrease of volume in the lumen of the four middle ear diseased ears compared to the control group. We observed a significant decrease in the volume of the protympanic space in the cholesteatoma group compared to the chronic otitis media group. We also observed a decrease in the bony space (protympanum space) in cholesteatoma, chronic otitis media with retraction pockets, and purulent otitis media compared to the control group. We found a correlation in middle ear diseases and a decrease in the middle ear space. Our findings may suggest that a smaller bony volume in the protympanic area may trigger middle ear dysventilation problems.

The surgical challenge of carotid artery and Fallopian canal dehiscence in chronic ear disease: a pitfall for endoscopic approach

OBJECTIVE

Endoscopic procedures are becoming common in middle ear surgery. Inflammation due to chronic ear disease can cause bony erosion of the carotid artery and Fallopian canals, making them more vulnerable during surgery. The objective of this study was to determine whether or not chronic ear disease increases dehiscence of the carotid artery and Fallopian canals.

DESIGN

Comparative human temporal bone study.

SETTING

Otopathology laboratory.

PARTICIPANTS

We selected 78 temporal bones from 55 deceased donors with chronic otitis media or cholesteatoma and then compared those two groups with a control group of 27 temporal bones from 19 deceased donors with no middle ear disease.

MAIN OUTCOME MEASURES

We analysed the middle ear, carotid artery canal and Fallopian canal, looking for signs of dehiscence of its bony coverage, using light microscopy.

RESULTS

We found an increased incidence in dehiscence of the carotid artery and Fallopian canals in temporal bones with chronic middle ear disease. The size of the carotid artery canal dehiscence was larger in the middle ear-diseased groups, and its bony coverage, when present, was also thinner compared to the control group. Dehiscence of the carotid artery canal was more frequently located closer to the promontory. The incidence of Fallopian canal dehiscence was significantly higher in temporal bones from donors older than 18 years with chronic middle ear disease.

CONCLUSION

The increased incidence of the carotid artery and Fallopian canal dehiscence in temporal bones with chronic middle ear disease elevates the risk of adverse events during middle ear surgery.

A three-dimensional analysis of the endolymph drainage system in Ménière disease

OBJECTIVES/HYPOTHESIS

To measure the volume of the endolymph drainage system in temporal bone specimens with Ménière disease, as compared with specimens with endolymphatic hydrops without vestibular symptoms and with nondiseased specimens STUDY DESIGN: Comparative human temporal bone analysis.

METHODS

We generated three-dimensional models of the vestibular aqueduct, endolymphatic sinus and duct, and intratemporal portion of the endolymphatic sac and calculated the volume of those structures. We also measured the internal and external aperture of the vestibular aqueduct, as well as the opening (if present) of the utriculoendolymphatic (Bast's) valve and compared the measurements in our three study groups.

RESULTS

The volume of the vestibular aqueduct and of the endolymphatic sinus, duct, and intratemporal endolymphatic sac was significantly lower in the Ménière disease group than in the endolymphatic hydrops group (P <.05). The external aperture of the vestibular aqueduct was also smaller in the Ménière disease group. Bast's valve was open only in some specimens in the Ménière disease group.

CONCLUSIONS

In temporal bones with Ménière disease, the volume of the vestibular aqueduct, endolymphatic duct, and intratemporal endolymphatic sac was lower, and the external aperture of the vestibular aqueduct was smaller as compared with bones from donors who had endolymphatic hydrops without vestibular symptoms and with nondiseased bones. The open status of the Bast's valve in the Ménière disease group could be secondary to higher retrograde endolymph pressures caused by smaller drainage systems. These anatomic findings could correlate with the reason that some patients with hydrops develop clinical symptoms, whereas others do not.

LEVEL OF EVIDENCE

N/A Laryngoscope, 127:E170-E175, 2017.

Histopathologic Evaluation of Vascular Findings in the Cochlea in Patients With Presbycusis

IMPORTANCE

Age-related changes in cochlear vessel wall thickness in human temporal bones have not been described previously.

OBJECTIVES

To compare thickness of the spiral modiolar artery and strial capillaries and to investigate strial atrophy and vessel loss in temporal bones with and without presbycusis.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective case-control study examined the autopsy reports of 1024 patients in the temporal bone collection at the University of Minnesota. Inclusion criteria consisted of being 60 years or older with sensorineural hearing loss and progression of hearing loss with age (presbycusis group). Age-matched controls had no record of hearing loss. All patients underwent pure-tone audiometry. Exclusion criteria included a history of otologic disease, ototoxic drug use, head or acoustic trauma, or systemic disease. Data were collected from October 1, 2013, to October 1, 2014.

MAIN OUTCOMES AND MEASURES

Vessel wall thickness in the modiolar artery and strial vessels, the strial area, and number of strial vessels were measured under light microscopy.

RESULTS

Among the 1024 autopsy reports examined, 11 patients (19 temporal bones) with presbycusis (7 men and 4 women; age range, 67-88 years; mean [SD] age, 78 [7] years]) and 15 controls (24 temporal bones) (7 men and 8 women; age range, 67-94 years; mean [SD] age, 79 [8] years) met the inclusion criteria. Compared with the control group, the presbycusis group had significantly increased mean (SD) thickness of vessel walls in the modiolar arteries (6.73 [2.39] vs 5.55 [0.86] μm; P = .02) and the strial capillaries in the lower basal (1.57 [0.21] vs 1.39 [0.15] μm; P = .005), upper basal (1.62 [0.28] vs 1.40 [0.13] μm; P < .001), lower middle (1.68 [0.22] vs 1.39 [0.20] μm; P < .001), upper middle (1.74 [0.39] vs 1.40 [0.19] μm; P = .01), and apical (1.70 [0.36] vs 1.47 [0.21] μm; P = .04) turns of the cochlea. Compared with the control group, the presbycusis group had significant loss of strial area in the lower basal (6614 [1559] vs 8790 [1893] μm2; P = .002), upper basal (6387 [2211] vs 9105 [2700] μm2; P < .001), lower middle (5140 [1471] vs 7269 [2181] μm2; P = .003), upper middle, (5583 [1742] vs 7206 [2258] μm2; P = .02), and apical (4286 [1604] vs 6535 [2454] μm2; P < .001) turns of the cochlea; in the vessel area in the lower basal turn (74.65 [127.74] vs 124.92 [89.04] μm2; P = .01); and in the number of vessels in the lower basal (1.00 [0.78] vs 1.94 [0.93]; P = .008) and lower middle (1.00 [0.78] vs 1.94 [0.93]; P = .04) turns of the cochlea.

CONCLUSIONS AND RELEVANCE

The histopathologic findings of increased thickness of the vascular walls of the modiolar arteries and stria vascularis, increased strial atrophy, and decreased number of strial vessels may have led to decreased cochlear microcirculation. Deficiency in the circulation and perfusion of the cochlea may be a factor in presbycusis.

Pathologic Findings of the Cochlea in Labyrinthitis Ossificans Associated with the Round Window Membrane

OBJECTIVE

To quantitatively demonstrate and classify the histopathologic changes in the cochlea of the human temporal bones with labyrinthitis ossificans (LO).

STUDY DESIGN

Comparative human temporal bone study.

SETTING

Tertiary academic medical center.

SUBJECTS AND METHODS

We compared 23 temporal bone specimens from 19 deceased donors with LO associated with the round window membrane (RWM) and 27 age-matched specimens from 20 deceased donors without any otologic diseases. We focused on the location of LO in the inner ear, the intensity of endolymphatic hydrops, the number of spiral ganglion cells and cochlear hair cells, and the areas of the stria vascularis and spiral ligament. In addition, we created a new pathologic grading system for temporal bone specimens from deceased donors with LO associated with the RWM.

RESULTS

We most often observed LO in the scala tympani of the basal cochlear turn. In the LO group (as compared with the control group), the intensity of endolymphatic hydrops was significantly increased; the number of spiral ganglion cells was significantly decreased in all segments; the loss of outer and inner hair cells was significantly increased in all turns of the cochlea; the atrophy of the stria vascularis was significantly greater in all turns of the cochlea; and atrophy of the spiral ligament was significantly greater in the basal and middle cochlear turn.

CONCLUSION

LO was associated with significant cochlear damage (to the spiral ganglion cells, cochlear hair cells, stria vascularis, and spiral ligament) and with increased intensity of endolymphatic hydrops.

Cochlear Changes in Patients with Type 1 Diabetes Mellitus

OBJECTIVE: To evaluate the effects of diabetes on cochlear elements in human beings.

STUDY DESIGN AND SETTING: Twenty-six temporal bones (mean age, 37.5 years) with type 1 diabetes and 30 age-matched controls were examined by light microscopy. We compared the findings of cochlear vessels, hair cells, spiral ganglion cells, and cochlear lateral walls.

RESULTS: In diabetics, the walls of vessels of the basilar membrane ( P < 0.001) and vessels of the stria vascularis were ( P < 0.01) significantly thicker in all turns and loss of outer hair cells (OHCs) was significantly greater in the lower basal turn ( P < 0.01). Atrophy of the stria vascularis in all turns ( P < 0.0001) and loss of spiral ligament cells in upper turns ( P < 0.01) were significantly higher than controls. No significant difference was obtained in the number of spiral ganglion cells between groups.

CONCLUSION: This study suggests that type 1 diabetes mellitus can cause cochlear microangiopathy and subsequently degeneration of cochlear lateral walls and OHCs.

Pathologic Changes of the Peripheral Vestibular System Secondary to Chronic Otitis Media

OBJECTIVE

To evaluate the histopathologic changes of dark, transitional, and hair cells of the vestibular system in human temporal bones from patients with chronic otitis media.

STUDY DESIGN

Comparative human temporal bone study.

SETTING

Otopathology laboratory.

SUBJECTS AND METHODS

To compare the density of vestibular dark, transitional, and hair cells in temporal bones with and without chronic otitis media, we used differential interference contrast microscopy.

RESULTS

In the chronic otitis media group (as compared with the age-matched control group), the density of type I and type II hair cells was significantly decreased in the lateral semicircular canal, saccule, and utricle (P < .05). The density of type I cells was also significantly decreased in the chronic otitis media group in the posterior semicircular canal (P = .005), but that of type II cells was not (P = .168). The mean number of dark cells was significantly decreased in the chronic otitis media group in the lateral semicircular canal (P = .014) and in the posterior semicircular canal (P = .002). We observed no statistically significant difference in the density of transitional cells between the 2 groups (P > .1).

CONCLUSION

The findings of our study suggest that the decrease in the number of vestibular sensory cells and dark cells could be the cause of the clinical symptoms of imbalance of some patients with chronic otitis media.

Epitympanum volume and tympanic isthmus area in temporal bones with retraction pockets

OBJECTIVES/HYPOTHESIS

To compare the volume of the epitympanic space, as well as the area of the tympanic isthmus, in human temporal bones with retraction pockets to those with chronic otitis media without retraction pockets and to those with neither condition.

STUDY DESIGN

Comparative human temporal bone study.

METHODS

We generated a three-dimensional model of the bony epitympanum and measured the epitympanic space. We also compared the area of the tympanic isthmus.

RESULTS

The mean total volume of the epitympanum was 40.55 ± 7.14 mm³ in the retraction pocket group, 50.03 ± 8.49 mm³ in the chronic otitis media group, and 48.03 ± 9.16 mm³ in the neither condition group. The mean volume of the anterior, lateral, and medial compartments in temporal bones in the retraction pocket group was significantly smaller than in the two control groups (P < 0.05). Total epitympanic volume was also significantly smaller in the retraction pocket group than in both control groups (P < 0.05). The mean area of the tympanic isthmus was significantly smaller in the retraction pocket group (8.11 ± 2.44 mm² ) than in the chronic otitis media group (9.82 ± 2.06 mm² ) or the neither condition group (10.66 ± 1.78 mm² ) (P < 0.05).

CONCLUSION

Our data indicate that temporal bones with retraction pockets have a smaller volume bony epitympanum and a smaller tympanic isthmus area as compared with temporal bones from both control groups. The smaller volume tympanic isthmus in the retraction pocket group may suggest that a blockage in the aeration pathways to the epitympanum could create dysventilation, resulting in negative pressure and ultimately in retraction pockets and cholesteatomas.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:E369-E374, 2016.

Peripheral vestibular pathology in Mondini dysplasia

OBJECTIVES/HYPOTHESIS

In this study, our objective was to histopathologically analyze the peripheral vestibular system in patients with Mondini dysplasia.

STUDY DESIGN

Comparative human temporal bone study.

METHODS

We assessed the sensory epithelium of the human vestibular system with a focus on the number of type I and type II hair cells, as well as the total number of hair cells. We compared those numbers in our Mondini dysplasia group versus our control group.

RESULTS

The loss of type I and type II hair cells in the cristae of the superior, lateral, and posterior semicircular canals, as well as in the saccular and utricular macula, was significantly higher in our Mondini dysplasia group than in our control group. The total number of hair cells significantly decreased in the cristae of the superior, lateral, and posterior semicircular canals, as well as in the saccular and utricular macula, in our Mondini dysplasia group.

CONCLUSION

Loss of vestibular hair cells can lead to vestibular dysfunction in patients with Mondini dysplasia.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:206-209, 2017.

Otopathologic Findings of Pena-Shokeir Syndrome Type I

BACKGROUND

Pena-Shokeir syndrome type I is a rare genetic disorder that includes multiple congenital facial and joint anomalies as well as pulmonary hypoplasia. Affected infants are usually premature, and 30% of them are stillborn. So far, studies have reported low-set ears in such infants, with no middle or inner ear findings.

METHOD

Histopathological study of human temporal bones with Pena-Shokeir syndrome type I.

RESULTS

Our case report describes an infant with severely decreased number of spiral ganglion cells and number of outer and inner hair cells of the cochlea, mild loss of vestibular hair cells, hypoplasia in the facial nerves, and ischemic degeneration of Schwann cells in the modiolus.

CONCLUSION

Pena-Shokeir syndrome type I is associated with a degenerative process in the labyrinth.

Scanning Electron Microscopic Examination of the Extracellular Matrix in the Decellularized Mouse and Human Cochlea

Decellularized tissues have been used to investigate the extracellular matrix (ECM) in a number of different tissues and species. Santi and Johnson JARO 14:3-15 (2013) first described the decellularized inner ear in the mouse, rat, and human using scanning thin-sheet laser imaging microscopy (sTSLIM). The purpose of the present investigation is to examine decellularized cochleas in the mouse and human at higher resolution using scanning electron microscopy (SEM). Fresh cochleas were harvested and decellularized using detergent extraction methods. Following decellularization, the ECM of the bone, basilar membrane, spiral limbus, and ligament remained, and all of the cells were removed from the cochlea. A number of similarities and differences in the ECM of the mouse and human were observed. A novel, spirally directed structure was present on the basilar membrane and is located at the border between Hensen and Boettcher cells. These septa-like structures formed a single row in the mouse and multiple rows in the human. The basal lamina of the stria vascularis capillaries was present and appeared thicker in the human compared with the mouse. In the mouse, numerous openings beneath the spiral prominence that previously housed the root processes of the external sulcus cells were observed but in the human there was only a single row of openings. These and other anatomical differences in the ECM between the mouse and human may reflect functional differences and/or be due to aging; however, decellularized cochleas provide a new way to examine the cochlear ECM and reveal new observations.

Cochlear changes in serous labyrinthitis associated with silent otitis media: A human temporal bone study

PURPOSE

To determine histopathological findings in the cochlea of human temporal bones with serous labyrinthitis.

MATERIALS AND METHODS

We compared human temporal bones with serous labyrinthitis (20 cases) associated with silent otitis media and without serous labyrinthitis (20 cases) to study location of serous labyrinthitis, the degree of endolymphatic hydrops, number of spiral ganglion cells and hair cells, loss of fibrocytes in the spiral ligament, and areas of the spiral ligament and stria vascularis.

RESULTS

The serous labyrinthitis caused significant loss of outer hair cells in the lower basal (P=0.006), upper basal (P=0.005), and lower middle (P=0.011) cochlear turns, and significant increase in the degree of endolymphatic hydrops than the control group (P=0.036). No significant difference was found in the loss of inner hair cells, in the number of spiral ganglion cells and fibrocytes in the spiral ligament, and in areas of the stria vascularis and spiral ligament (P>0.05).

CONCLUSIONS

Serous labyrinthitis resulted in significant loss of outer hair cells and significant increase in the degree of endolymphatic hydrops.

Stria vascularis and cochlear hair cell changes in syphilis: A human temporal bone study

OBJECTIVE

To observe any changes in stria vascularis and cochlear hair cells in patients with syphilis.

MATERIALS AND METHODS

We examined 13 human temporal bone samples from 8 patients with syphilis (our syphilis group), as well as 12 histopathologically normal samples from 9 age-matched patients without syphilis (our control group). We compared, between the two groups, the mean area of the stria vascularis (measured with conventional light microscopy connected to a personal computer) and the mean percentage of cochlear hair cell loss (obtained from cytocochleograms).

RESULTS

In our syphilis group, only 1 (7.7%) of the 13 samples had precipitate in the endolymphatic or perilymphatic spaces; 8 (61.5%) of the samples revealed the presence of endolymphatic hydrops (4 cochlear, 4 saccular). The mean area of the stria vascularis did not significantly differ, in any turn of the cochlea, between the 2 groups (P>0.1). However, we did find significant differences between the 2 groups in the mean percentage of outer hair cells in the apical turn (P<0.026) and in the mean percentage of inner hair cells in the basal (P=0.001), middle (P=0.004), and apical (P=0.018) turns. In 7 samples in our syphilis group, we observed either complete loss of the organ of Corti or a flattened organ of Corti without any cells in addition to the absence of both outer and inner hair cells.

CONCLUSION

In this study, syphilis led either to complete loss of the organ of Corti or to significant loss of cochlear hair cells, in addition to cochleosaccular hydrops. But the area of the stria vascularis did not change.

A rare location for sarcoma metastasis: The temporal bone

Skeletal sarcoma metastasis is relatively rare; moreover, for this type of metastasis, the temporal bone is also a rare location. The temporal bone appears to be affected by metastatic tumors in discrete histopathologic patterns, with characteristic clinical presentations. In this study, we analyzed the records of 6 patients with skeletal sarcoma metastasis to the temporal bone, with an emphasis on histopathologic sections of human temporal bones. The most common site of sarcoma metastasis in the temporal bone was petrous apex in our series. Physicians should keep in mind that a sarcoma patient may manifest with ear findings due to temporal bone metastasis.

Quantitative assessment of vestibular otopathology in otosclerosis: A temporal bone study

OBJECTIVES/HYPOTHESIS

To determine if peripheral vestibular otopathology is present in human temporal bones with otosclerosis.

STUDY DESIGN

Comparative human temporal bone study.

METHODS

Seventy-four human temporal bones from 46 subjects with otosclerosis (mean age of 61 ± 18 years) and 20 within histologically normal limits from 17 subjects (mean age of 59 ± 14 years) were included in this study. Temporal bones with otosclerosis were divided into those with and without endosteal involvement. Using differential interference contrast microscopy at 1008× magnification, type I and type II vestibular hair cell counts were performed on each vestibular sense organ in which the neuroepithelia was oriented perpendicular to the plane of section. The organ-specific cell densities (cells/0.01 mm(2) surface area) were compared between the groups with and without endosteal involvement, and also compared to counts in the nonotosclerosis control group using Student's t-test.

RESULTS

Mean type I and type II hair cell densities of all vestibular structures in the group with endosteal involvement were significantly lower compared to the group without endosteal involvement. Mean type I and type II hair cell densities of all vestibular structures in the group with endosteal involvement were also significantly lower compared to the control group, but they were not in the group without endosteal involvement compared to the control group.

CONCLUSION

Endosteal involvement of otosclerotic foci is associated with vestibular hair cell loss that may contribute to the vestibular symptoms in otosclerosis.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 126:E118-E122, 2016.

Quantitative Vestibular Labyrinthine Otopathology in Temporal Bones with Vestibular Schwannoma

Objective

Dizziness associated with vestibular schwannoma is usually ascribed to retrolabyrinthine mechanisms. The goal of this study was to determine if quantitative peripheral vestibular (labyrinthine) otopathology was present in a series of patients with vestibular schwannoma.

Study Design

Comparative human temporal bone study.

Setting

Otopathology laboratory.

Subjects and Methods

Temporal bones from 12 subjects with unilateral sporadic vestibular schwannoma were included. Based on differential interference contrast microscopy, type I and II vestibular hair cell counts were performed on each vestibular sense organ with minimal autolysis in which the neuroepithelium was oriented perpendicular to the plane of section. Hair cell densities (cells per 0.01-mm2 surface area) and the presence of endolymphatic hydrops and precipitate within the endolymph or perilymph were compared between the tumor ears and the contralateral (control) ears.

Results

Compared with the contralateral ears, vestibular schwannoma ears had significantly more endolymphatic hydrops ( P = .049) and precipitate in the endolymph and perilymph ( P = .005), lower densities of type I and II vestibular hair cells in the lateral canal cristae (mean differences, respectively: 25.2 [ P = .001] and 10.8 [ P < .001]) and utricle (mean differences, respectively: 26.8 and 10.4 [ P < .001]), and lower densities of type I hair cells and the same density of type II hair cells in the saccule (mean differences, respectively: 26.5 [ P < .001] and 0.9 [ P = .46]).

Conclusion

Peripheral vestibular otopathology, manifested as reductions of vestibular hair cell densities, was identified in ears with vestibular schwannoma. Labyrinthine as well as retrolabyrinthine pathology may contribute to tumor-related vestibular dysfunction.

Macromolecular organization and fine structure of the human basilar membrane - RELEVANCE for cochlear implantation

INTRODUCTION

Cochlear micromechanics and frequency tuning depend on the macromolecular organization of the basilar membrane (BM), which is still unclear in man. Novel techniques in cochlear implantation (CI) motivate further analyses of the BM.

MATERIALS AND METHODS

Normal cochleae from patients undergoing removal of life-threatening petro-clival meningioma and an autopsy specimen from a normal human were used. Laser-confocal microscopy, high resolution scanning (SEM) and transmission electron microscopy (TEM) were carried out in combination. In addition, one human temporal bone was decellularized and investigated by SEM.

RESULTS

The human BM consisted in four separate layers: (1) epithelial basement membrane positive for laminin-β2 and collagen IV, (2) BM "proper" composed of radial fibers expressing collagen II and XI, (3) layer of collagen IV and (4) tympanic covering layer (TCL) expressing collagen IV, fibronectin and integrin. BM thickness varied both radially and longitudinally (mean 0.55-1.16 μm). BM was thinnest near the OHC region and laterally.

CONCLUSIONS

There are several important similarities and differences between the morphology of the BM in humans and animals. Unlike in animals, it does not contain a distinct pars tecta (arcuate) and pectinata. Its width increases and thickness decreases as it travels apically in the cochlea. Findings show that the human BM is thinnest and probably most vibration-sensitive at the outer pillar feet/Deiter cells at the OHCs. The inner pillar and IHCs seem situated on a fairly rigid part of the BM. The gradient design of the BM suggests that its vulnerability increases apical wards when performing hearing preservation CI surgery.

Epitympanic Area and Volume in Human Temporal Bones with and without Chronic Otitis Media

Objectives:

(1) Investigate the difference in epitympanic bony volume and size of tympanic isthmus (TI) between human temporal bones (HTBs) with and without chronic otitis media (COM). (2) Investigate the relationship between TI size and epitympanic bony volume in HTBs with and without COM.

Methods:

Eleven HTBs from children with COM (COM group) and 11 HTBs without COM (control group) were examined. Three-dimensional models were generated from HTB histopathologic slides with reconstruction software (Amira), and epitympanic bony volumes were measured. Within the boundaries of TI, only the aerated space, excluding exudates and soft tissues, were measured as aerated TI, and all space surrounded by the boundaries including exudates and soft tissues were measured as the bony TI. We chose the minimum aerated/bony TI area from all slides and compared them between the 2 groups. We also investigated the correlation between bony epitympanic volume and minimum aerated/ bony TI area in each group.

Results:

There were no significant differences in epitympanic bony volume or bony TI area between the groups. Aerated TI area in the COM group was significantly smaller than in control group ( P < .01). There was no relationship between aerated TI area and bony epitympanic volume in the 2 groups. In the COM group, there was a negative correlation between bony TI area and epitympanic volume ( P < .001).

Conclusions:

Our study suggests that congenital or developmental stenosis of the TI is not associated with epitympanic pathology, but blockage of TI with soft tissue pathology is.

Association of Endolymphatic Hydrops and Otosclerosis

Objectives:

Study the correlations of endolymphatic hydrops and vestibular symptoms with otosclerotic foci.

Methods:

Comparative study of human temporal bone histopathology. In addition to areas of the stria vascularis and spiral ligament and the presence of endolymphatic hydrops, locations and degree of endosteal involvement and size of otosclerotic foci were examined in 132 temporal bones from 95 subjects with otosclerosis. The degree of endolymphatic hydrops was classified as mild, moderate and severe.

Results:

Fifty temporal bones (37.9%) from 39 subjects with otosclerosis had a histopathological finding of endolymphatic hydrops. The most common location of endosteal involvement was the endosteum of the perilymphatic space of the vestibule. In terms of locations and degree of endosteal involvement and size of otosclerotic foci, there was a significant increase in subjects with otosclerosis with endolymphatic hydrops compared with subjects with otosclerosis without endolymphatic hydrops. Twenty five subjects (26.3%) had a documented history of vestibular symptoms in patients with otosclerosis. In addition to the presence of endolymphatic hydrops, locations and degree of endosteal involvement and size of otosclerotic foci were significantly greater in subjects with otosclerosis with vestibular symptoms compared with subjects with otosclerosis without vestibular symptoms.

Conclusions:

Endolymphatic hydrops is more common than previously realized in patients with otoslerosis. The common association of these 2 otologic conditions encourages researchers. Clinicians should keep in mind the common association of these 2 otologic conditions when encountering a patient with either of these conditions.

Pneumococcal PspA and PspC proteins: potential vaccine candidates for experimental otitis media

OBJECTIVE

Otitis media is the most commonly diagnosed disease in ambulatory care and Streptococcuspneumoniae continues to be the most common bacterial agent. Bacterial resistance to antibiotics underscores the need for better vaccines. Current pneumococcal conjugate vaccines are modestly protective against otitis media; however, limited serotype coverage and serotype replacement have led to the investigation of pneumococcal proteins as potential vaccine candidates. Two proteins, pneumococcal surface proteins A (PspA) and C (PspC) are important virulence factors, expressed by virtually all strains. Although a number of pneumococcal proteins have been investigated in other infection sites, these proteins can have diverse organ-specific effects. In this study, we investigated the viability and virulence of single (PspA(-) and PspC(-)) and double (PspA(-)/PspC(-)) mutants of pneumococcal PspA and PspC proteins in the chinchilla middle ear.

METHODS

Bullae of 24 chinchillas were inoculated with 0.5 ml of 10(6) colony forming units (CFUs)/ml bacteria: 6 with wild-type D39 strain; 6 with PspA(-); 6 with PspC(-); and 6 with PspA(-)/PspC(-) isogenic mutant strains. Bacterial CFU levels in middle ear effusions and light microscopic analysis of the number of inflammatory cells in the round window membrane (RWM) were compared 48 h after inoculation.

RESULTS

At 48 h, CFUs in middle ears were increased for wild-type and PspC(-) strains compared to inoculum levels; however, they were significantly less for the group inoculated with the PspC(-) strain compared to wild-type strain. No bacteria were detected in the PspA(-) and PspA(-)/PspC(-) groups. The number of inflammatory cells in the RWM was significantly higher in wild-type compared to the PspA(-), PspC(-), and PspA(-)/PspC(-) groups. No significant difference in number of inflammatory cells was observed between any pairs of groups inoculated with mutant strains.

CONCLUSION

Viability and virulence of the PspC(-) strain were similar to the wild-type strain. The single PspA(-) and double PspA(-)/PspC(-) mutants were highly attenuated in the ear. Bacterial clearance of the PspA(-)/PspC(-) double mutant was indistinguishable from that of the PspA mutant. These studies provide no reason to exclude PspC from a multi-component protein vaccine containing PspA.

The pathology of silent otitis media: a predecessor to tympanogenic meningitis in infants

OBJECTIVE

To determine the association of bacteria embedded within a fibrous matrix in the middle and inner ear in infants with tympanogenic meningitis.

METHODS

Thirty-one cases with meningitis from the human temporal bone collection at the University of Minnesota were screened to select those with tympanogenic meningitis. Inclusion criteria for tympanogenic meningitis were acute meningitis with histopathological evidence of chronic otitis media, and no other source of infection. The presence of labyrinthitis and pathologic changes such as granulation tissue, fibrosis, cholesterol granuloma, cholesteatoma, tympanic membrane perforation, tympanosclerosis, and the type of effusion were noted. The extent and location of bacteria embedded in a fibrous matrix were also explored.

RESULTS

Seventeen temporal bones, from nine cases that included two females and seven males, ranging in age from five to twenty-three months, met our criteria of tympanogenic meningitis. Eighty two percent of these temporal bones had bacteria within the fibrous matrices (BFM). BFM were located in one anatomical region in one temporal bone and multiple anatomic regions in sixteen temporal bones. The most common locations were the areas near the oval and round windows. They were also commonly seen in the epitympanum, facial recess, and supratubal recess. BFM within the inner ear were observed in the scala tympani and modiolus in the middle and basal turns of the cochleae of nine temporal bones. In one of these temporal bones, BFM were seen in the internal auditory canal. Labyrinthitis was seen in all ears. The tympanic membrane was intact in all cases. BFM were not seen in three temporal bones from two patients. In one case only one side was available for study.

CONCLUSIONS

Our findings show an association between the presence of BFM in the ear with chronic pathologic changes and tympanogenic meningitis. Potential pathways of bacteria from the middle ear include hematogeous spread and/or direct spread to dura through the tympanic tegmen, and/or to the inner ear through the oval and round windows, and from there to the modiolus and the meninges. Chronic pathologic changes in the middle ear behind an intact tympanic membrane and the lack of ear symptoms may result in potentially serious sequelae and complications in infant age groups. There should be a heightened awareness of this condition.

Viability and virulence of pneumolysin, pneumococcal surface protein A, and pneumolysin/pneumococcal surface protein A mutants in the ear

IMPORTANCE

Understanding how pneumococcal proteins affect the pathology of the middle ear and inner ear is important for the development of new approaches to prevent otitis media and its complications.

OBJECTIVES

To determine the viability and virulence of Streptococcus pneumoniae mutants deficient in pneumolysin (Ply-) and pneumococcal surface protein A (PspA-) in the chinchilla middle ear.

DESIGN

Bullae of chinchillas were inoculated bilaterally with wild-type (Wt), Ply-, PspA-, and Ply-/PspA- strains. Bacterial colony-forming units (CFUs) in middle ear effusions were counted at 48 hours. The CFUs of the PspA- group were also counted at 6 to 36 hours after inoculation. Temporal bone histopathological results were compared.

SETTING AND PARTICIPANTS

Twenty-seven chinchillas in an academic research laboratory.

EXPOSURE

Chinchilla middle ears were inoculated with S pneumoniae to produce sufficient volumes of effusions and noticeable histopathological changes in the ears.

MAIN OUTCOMES AND MEASURES

The CFU counts in the middle ear effusions and histopathological changes were compared to determine the effect of pneumococcal protein mutations on chinchilla ears.

RESULTS

At 48 hours, CFUs in middle ears were increased for the Wt and Ply-/PspA- strains, but Ply- remained near inoculum level. No bacteria were detected in the PspA- group. The CFUs of PspA- decreased over time to a low level at 30 to 36 hours. In vitro, PspA- in Todd-Hewitt broth showed an increase in bacterial growth of 2 logs at 43 hours, indicating PspA- susceptibility to host defenses in vivo. The PspA- and Ply- groups had fewer pathologic findings than the Wt or Ply-/PspA- groups. Histopathological analysis showed significant differences in the number of bacteria in the scala tympani in the Wt group compared with the Ply-, PspA-, and Ply-/PspA- groups. The PspA- strain was the least virulent.

CONCLUSIONS AND RELEVANCE

The PspA- mutant was much less viable and less virulent in the ear than the Wt, Ply-, and Ply-/PspA- strains. There was no significant attenuation in the viability and virulence of the Ply-/PspA- mutant compared with the Wt or single mutants. The viability and virulence of pneumococcal mutants seemed to be protein and organ specific.

Facial nerve canal dehiscence in chronic otitis media without cholesteatoma

The information on incidence of the facial nerve canal dehiscence in chronic otitis media is important for surgeons. The purpose of this study is to disclose the histopathologic findings of facial nerve canal dehiscence in human temporal bones with chronic otitis media. We divided the human temporal bones into two groups (age 4 years, and under 4 years of age). We evaluated the incidence and the area of the facial nerve canal dehiscence in chronic otitis media under light microscopy. Age-matched normal control temporal bones were also examined. In the age group of 4 years, 68.9 % of temporal bones with chronic otitis media and 71.9 % of controls had the facial nerve canal dehiscence. There was no significant difference between them (P = 0.61). The area of the dehiscence in temporal bones with chronic otitis media was not statistically different from controls (P = 0.53). In the age group under 4 years, 88.2 % of temporal bones with chronic otitis media and 76.5 % of controls had the dehiscence. No significant difference was found between them (P = 0.66). The area of the dehiscence in temporal bones with chronic otitis media was not statistically different from controls in the age group under 4 years (P = 0.43). In chronic otitis media, the incidence of facial nerve canal dehiscence was high and was not statistically different from controls. These results suggest that there is no association between chronic otitis media and the presence of facial nerve canal dehiscence.

The Continuum of Biofilms in Different Types of Otitis Media

Objective: It is recognized that the various types of otitis media (OM) follow a continuum with early forms of the disease leading to more chronic forms over time. This study investigates if biofilms play a role in conjunction with the continuum of pathological changes in different stages of OM.

Method: Thirty human temporal bones of each type, sero- purulent OM (SPOM), purulent OM (POM), chronic OM with purulent effusion (PCOM), and fourteen mucoid OM (MOM), were selected. We defined “web-like structures” with host defense cells and bacterial bodies as biofilm. We examined the occurrence, frequency, and anatomic locations of biofilms.

Results: Biofilms were observed in 10 (33.3%) of the 30 temporal bones with SPOM, 19 (63.3%) with POM, and 20 (66.7%) with PCOM. A significant difference of biofilms’ frequency between SPOM and POM ( P = .038), and SPOM and PCOM ( P = .017), was observed. The most common anatomic location was mastoid antrum and mastoid cells (35 of 49 temporal bones, 71.4%). The number of anatomic locations with biofilms was 2.20 ± 1.03 in SPOM, 2.89 ± 1.70 in POM, and 4.15 ± 1.60 in PCOM. There was a significant difference of locations between PCOM and SPOM ( P < .001), and PCOM and POM ( P = .022).

Conclusion: The frequency of biofilms suggests that the presence of biofilms is associated with the severity of OM. The growth and development of biofilms may play an important role in the progression of chronicity of OM.

Dysfunction of the cochlea contributing to hearing loss in acoustic neuromas: an underappreciated entity

OBJECTIVE

Hearing loss is a common symptom in patients with cochleovestibular schwannoma. Clinical and histologic observations have suggested that the hearing loss may be caused by both retrocochlear and cochlear mechanisms. Our goal was to perform a detailed assessment of cochlear pathology in patients with vestibular schwannoma (VS).

STUDY DESIGN

Retrospective analysis of temporal bone histopathology.

SETTING

Multi-center study.

MATERIAL

Temporal bones from 32 patients with unilateral, sporadic VS within the internal auditory canal.

MAIN OUTCOME MEASURES

Sections through the cochleae on the VS side and opposite (control) ear were evaluated for loss of inner and outer hair cells, atrophy of the stria vascularis, loss of cochlear neurons, and presence of endolymphatic hydrops and precipitate within the endolymph or perilymph. Observed pathologies were correlated to nerve of origin, VS volume, and distance of VS from the cochlea. Hearing thresholds also were assessed.

RESULTS

VS caused significantly more inner and outer hair cell loss, cochlear neuronal loss, precipitate in endolymph and perilymph, and decreased pure tone average, when compared with the opposite ear. Tumor size, distance from the cochlea, and nerve of origin did not correlate with structural changes in the cochlea or the hearing threshold.

CONCLUSION

There is significant degeneration of cochlear structures in ears with VS. Cochlear dysfunction may be an important contributor to the hearing loss caused by VS and can explain certain clinically observed phenomena in patients with VS.