Anatomy of the para-vestibular canaliculus

A histologic study of the para-vestibular canaliculus (PVC), its contents, and its relationship to the vestibular aqueduct (VA), is presented. 20 normal human temporal bones were fixed in 10% formalin solution, embedded in celloidin, and sectioned horizontally at intervals of 20 micrometers. Every tenth section was stained with hematoxylin and eosin (HE) and studied under a light microscope. Three significant observations were made. First, in 80% of the specimens, two rather than one PVC were found in the area of the vestibular orifice of the VA. Second, in 70% of the specimens, the PVC was found to merge with the VA rather than to enter the posterior cranial fossa (PCF) separately. Third, in all the specimens examined, a vein was seen to traverse the entire length of the PVC. However, in 17 specimens, no artery could be identified within the PVC. In the 13 (65%) specimens in which arteries could be identified in the PVC, the arteries extended only half the length of the PVC, from the PCF to the VA. In no specimen examined could arteries be seen extending the full length of the PVC from the PCF to the vestibule.

The potential risk of carotid injury in cochlear implant surgery

BACKGROUND

The advent of cochlear implantation has revolutionized the options afforded to the deaf population. With the increase in the prevalence of this procedure have come larger experiences in the associated technical challenges and complications.

RESULTS

We present the evaluation and management of a patient with an unusual complication of improper placement of the implant electrode into the carotid canal and its management. We discuss the anatomy of the carotid artery and its proximity to the cochlea to emphasize the potential risk to this large vessel.

CONCLUSIONS

Damage to the carotid canal and the carotid artery is a potential risk of cochlear implant surgery. When available, we recommend intraoperative electrical testing of the cochlear implant be performed. If there is doubt as to the placement of the electrode, a radiograph should be obtained before the patient is taken out of the operating room to avoid this complication.

Vestibular abnormalities in congenital disorders

This paper reviews the histopathologic features of vestibular abnormalities in congenital disorders affecting the inner ear, based upon a comprehensive literature survey and a review of cases in our temporal bone collection. The review proceeds in three systematic steps. First, we surveyed associated diseases with the major phenotypic features of congenital abnormalities of the inner ear (including the internal auditory canal and otic capsule). Second, the vestibular anomalies are examined specifically. Finally, the anomalies are discussed from a developmental perspective. Among vestibular anomalies, a hypoplastic endolymphatic duct and sac are observed most frequently. Anomalies of the semicircular canals are also often observed. From embryological and clinical viewpoints, many of these resemble the structural features from fetal stages and appear to be associated with vestibular dysfunction. It is expected that progress in genetic analysis and accumulation of temporal bone specimens with vestibular abnormalities in congenital diseases will provide crucial information not only for pathology of those diseases, but also for genetic factors that are responsible for the specific vestibular abnormalities.

Histopathologic study of temporal bone and eustachian tube in oculoauriculovertebral spectrum

Bilateral temporal bone specimens from a 21-month-old girl and a left temporal bone-eustachian tube (ET) specimen from a full-term female newborn, both with oculoauriculovertebral spectrum, were studied histopathologically. The external and middle ears demonstrated severe anomalies, similar to those of previous reports describing the histopathologic findings of this syndrome. In addition, despite having a normal auricle, the 21-month-old child had bilateral hypoplastic cochleas as seen in Mondini dysplasia. The newborn had several anomalies of the ET, including a widely opened cartilaginous portion of the ET lumen and absence of the lateral lamina of the ET cartilage. We discuss the implications of the observed anomalies with regard to developmental and clinical issues.

Temporal bone histopathological study of Noonan syndrome

Four temporal bone specimens, obtained from three individuals 1--6 years of age with Noonan syndrome (NS), were studied histopathologically. All four specimens were accompanied by similar inner ear abnormalities including the reduced number of spiral ganglion cells, enlarged lateral semicircular canal, and dislocated endolymphatic sac and vestibular aqueduct. The mean population of spiral ganglion cells (15,699 cells) was approximately half of those (32,978 cells) in four age-matched control cases. In addition, they had several middle ear abnormalities including the remaining mesenchyme and dehiscence of the facial canal. To our knowledge, this is the first report to describe the histopathological temporal bone findings in patients with NS. We discuss the implications of the observed abnormalities with regard to clinical issues.

Mucosa-associated lymphoid tissue in middle ear and eustachian tube

The presence of mucosa-associated lymphoid tissue (MALT) was investigated histopathologically in every 20th section from 99 vertically cut, celloidin-embedded temporal bone-eustachian tube (ET) specimens. Among specimens from infants and children between 1 month and 7 years of age, MALT was found in 22 of 44 (50%). However, in 26 adults over 18 years of age, MALT was found in only 2 specimens (7.7%), a significantly lower incidence than that in infants and children. Moreover, MALT did not appear in any of the 21 neonates under the age of 1 month. All 99 specimens were classified into 2 groups: 41 specimens with otitis media (OM) and 58 specimens without OM. The presence of MALT was significantly higher in specimens with OM (43.9%) than in specimens without OM (13.8%). Mucosa-associated lymphoid tissue was found in the ET, middle ear, and mastoid process in 18 specimens (43.9%). 5 specimens (12.2%), and 1 specimen (2.4%) with OM, respectively, and in 8 (13.8%), 0, and 0 specimens without OM. In regard to the distribution of MALT, it occurred more frequently in the pharyngeal half of the cartilaginous portion of the ET than in the rest of the ET, middle ear, and mastoid; the presence was significantly greater in the inferior half of the cartilaginous portion of the ET than in the superior half. Inflammatory cell infiltration in the cartilaginous and bony portions of the ET was significantly greater in specimens with OM than in specimens without OM with no MALT. However, even in some specimens without OM, inflammatory cells were found in the ET, particularly in the pharyngeal half of the cartilaginous portion of the ET. These findings suggest that MALT has a close relationship to OM and that it may be a local response to repeated infection.

Histopathological study on temporal bone and eustachian tube in trisomy 22

Two temporal bone-eustachian tube (ET) specimens, one from a 34-gestational week-old male newborn and the other from a 3-month-old female infant, both with trisomy 22, were studied histopathologically. Both cases demonstrated severe inner-ear anomalies including hypoplastic cochlea, atrophy of the saccular macula, and dislocated endolymphatic sac and vestibular aqueduct. In addition, they had several anomalies in the ET including widely developed medial lamina of the ET cartilage, undeveloped lateral lamina of the ET cartilage, and absence of attachment of the tensor veli palatini muscle to the ET cartilage. We discuss the implications of the observed anomalies with regard to developmental and clinical issues.

Length of the eustachian tube and its postnatal development: computer-aided three-dimensional reconstruction and measurement study

Eleven normal human temporal bone-eustachian tube (ET) specimens obtained from 11 individuals whose ages were 3 months to 88 years were studied to investigate the path length along the ET lumen and its postnatal development by means of a computer-aided 3-dimensional reconstruction and measurement method. The path length of the ET lumen of the 3-month-old infant was 21.2 mm, and its growth was in correlation with age to attain its adult length (average, 37.00 +/- 4.16 mm). The ratio of the length of the cartilaginous portion together with the junctional portion to the length of the bony portion was 8:1 in an infant at the age of 3 months and 4:1 in adults. That the bony portion of the ET develops relatively more than the cartilaginous and junctional portions may cause this finding. In addition, there is a developmental shift in the orientation of the cartilaginous portion with respect to the bony portion of the ET. In children, the cartilaginous and bony portions are both aligned with the line that connects the pharyngeal orifice and the tympanic orifice. In adults, however, the cartilaginous portion is angled inferiorly and laterally from the bony portion. This change may reflect the relative growth of the face.

Cellular distribution of mucosa-associated lymphoid tissue with otitis media in children

This study examined mucosa-associated lymphoid tissue (MALT) in the eustachian tube (ET), middle ear (ME), and mastoid antrum (MA) in 163 celloidin-embedded temporal bones from children with or without otitis media. Otitis media was defined by the presence of histopathologically identified inflammatory cell infiltration in the mucosa or cavity of the ME. We found MALT in the ET in 30 cases (46.2%), in the ME in 19 cases (29.2%), and in the MA in 4 cases (6.2%) out of 65 cases of otitis media, and in the ET in 7 (7.1%), in the ME in 0, and in the MA in 0 out of 98 specimens without otitis media. No MALT appeared in any children under the age of 1 month. Immunohistochemical methods were used to investigate MALT in 12 horizontally cut temporal bones with OM. The follicular area contained OPD4-positive (helper-inducer T) cells and a few CD8-positive (cytotoxic and suppressor T) cells, whereas the parafollicular area contained OPD4-positive and CD8-positive T cells. CD57-positive (natural killer) cells were confined to the germinal center. CD30-positive (activated T and B) cells were observed throughout the follicles. A few CD15-positive (granulocyte, monocyte) cells were found in the follicles. Histopathologic and immunohistochemical findings were indistinguishable for MALT in the ET, ME, and MA. Our results suggest that MALT may be a mechanism for producing a rapid and massive local immune reaction to repeated bacterial infections via the ET.

Histopathologic study of the human eustachian tube and its surrounding structures following irradiation for carcinoma of the oropharynx

OBJECTIVE

To describe a histopathologic analysis of a human temporal bone demonstrating patulous changes of the eustachian tube (ET) and its surrounding structures following radiation therapy.

DESIGN

Retrospective histopathologic case review and comparison with an age-matched control.

SETTING

Elizabeth McCullough Knowles Otopathology Laboratory, University of Pittsburgh School of Medicine, Pittsburgh, Pa.

RESULTS

A widened patulous ET was verified by demonstrating fibrous tissue replacement of the surrounding supporting structures related to the ET. The ET lumen was patulous and wider than the control case. Ostmann fatty tissue, the levator veli palatini muscle, and submucosal glands around the ET cartilage were replaced by dense connective tissue.

CONCLUSION

This is the first histopathologic report, to our knowledge, demonstrating the effects on the ET lumen and supporting structures following acute weight loss, possible tumor infiltration, and radiation changes for carcinoma of the oropharynx.

Ossification of eustachian tube cartilage and Ostmann's fatty tissue in chronic renal failure

Ossification of the eustachian tube (ET) cartilage in 2 cases of chronic renal failure is reported for the first time. In both cases, the ossification was observed in the medial lamina of the ET cartilage. In addition, ossification of Ostmann's fatty tissue was observed in case 1, and ossification of the lateral lamina of the ET cartilage was seen in case 2. Correlation between ossification in chronic renal failure and dysfunction of the ET caused by ossified ET cartilage and Ostmann's fatty tissue is discussed.

Postnatal development of the tympanic cavity: a computer-aided reconstruction and measurement study

A computer-aided 3-D reconstruction and measurement method was used to assess postnatal volume and height changes in the tympanic cavity. Materials used were 14 normal human temporal bones obtained from 6 infants (under 1 year of age) and 8 adults (over 18 years of age). After defining the boundaries of the tympanic cavity, its total volume and height and the volume and height of the epitympanum, mesotympanum and hypotympanum were measured. The relationship between the volume of the tympanic cavity and age, and the correlation between the volume of the tympanic cavity and the grade of pneumatization of the air cells were also studied. The average volume of the tympanic cavity in adults (640.1+/-69.1 mm3, n = 8) was about 1.5 times larger than the volume of the infant cavity (451.7+/-68.2 mm3, n = 6). The hypotympanum increased most postnatally and the mesotympanum least. The volume of the tympanic cavity increased in proportion to increasing pneumatization in bone surrounding the cavity. The postnatal increase in the height of the tympanic cavity appears to be the major contributor to the increase in volume of the cavity. Postnatal changes in the tympanic cavity have clinical implications.

Postnatal development of eustachian tube cartilage. A study of normal and cleft palate cases

Infants with cleft palate (CP) display eustachian tube (ET) dysfunction. This study compared the postnatal development of the volume of ET cartilage in 34 normal cases and 10 CP cases using a personal computer. In cases with age under 1 month old, the total volume of ET cartilage was 61.94+/-20.89 mm(3) (mean+/-S.D.) in 16 normal control cases and 50.07+/-24.69 mm(3) in nine CP cases (t-test, not significantly different from normal). The ratio of lateral lamina (LL) to medial lamina (ML) volume (LL/ML) was reduced significantly (t-test, P<0.001) from 0.23+/-0.07 in 16 normal control cases to 0.09+/-0.05 in nine CP cases under 1 month old. In 34 normal ET cases whose ages were under 20 years, statistically significant positive correlations were found between the total volume of ET cartilage (y1) and age (x), volume of LL (y2) and age, and volume of ML (y3) and age (P<0.01, r=0.731, 0.614, 0.719). The regression lines were y1=20.37x+95.57, y2=2.02x+15.60, and y3=18. 35x+79.97. With the result obtained from this study, it is assumed that immaturity of the ET cartilage in infants, especially that of LL of the ET cartilage in CP infants, may be a significant risk factor for developing otitis media with effusion.

Multiple temporal bone anomalies in isotretinoin syndrome: a temporal bone histopathologic case report

Vitamin A and its derivatives are known teratogens. To our knowledge, this is the second temporal bone histopathologic report on anomalies related to these substances. A white boy (aged 4 years 5 months at death) was born with a complex central nervous system dysgenesis related to his mother's use of isotretinoin (Accutane) early in pregnancy. Histopathologic examination revealed multiple anomalies in the temporal bones: a narrow external auditory canal, protrusion of bone marrow into the middle ear cavity, anomalies of the ossicles, hypoplasia of the facial nerve, absence of the chorda tympani nerve and the stapedius muscle, anomalies of the membranous labyrinth in the vestibule, a hypoplastic lateral semicircular canal, and a large vestibular aqueduct and endolymphatic sac.

Histopathological changes of the eustachian tube cartilage and the tensor veli palatini muscle with aging

OBJECTIVES

The eustachian tube (ET) and the tensor veli palatini muscle (TVPM) are thought to play an important role in ventilatory function. Calcification of the ET cartilage and the replacement of TVPM by fat tissue are often observed histologically in elderly patients. To our knowledge, however, there are no quantitative studies of these pathological findings in relation to age.

STUDY DESIGN

The calcification of the ET cartilage and the atrophy of the TVPM in 36 normal human temporal bones obtained from 36 individuals with ages ranging from 2 days to 88 years were investigated.

METHODS

The number of calcified chondrocytes in the midportion of the ET cartilage was quantified as the average number of cells per square millimeter. Atrophy of the TVPM was evaluated at the midportion of the site where the TVPM is attached to the tip of lateral lamina of ET cartilage. A grade of 0, 1, 2, 3, or 4 was assessed for each section, which indicated approximately 0% to 5%, 5% to 30%, 30% to 70%, 70% to 95%, or 95% to 100% of the TVPM replacement by fat tissue, respectively.

RESULTS

A statistically significant correlation was found between the number of the calcified cells and aging (P < .001). A statistically significant correlation was also found between the degree of the atrophy of TVPM and aging (P < .001).

CONCLUSIONS

The calcification of the ET cartilage and the atrophy of the TVPM are closely associated with aging. Therefore, it is suggested that these two findings may be a predisposing factor for ET dysfunction in elderly adults.

Distribution of psammoma bodies in the internal auditory canal and its extended areas in the human temporal bone

The internal auditory canal (IAC) and its extended areas of 27 normal human temporal bone specimens were investigated histologically for the distribution of psammoma bodies. A total of 145 +/- 25 (mean +/- SE) psammoma bodies were counted in series of every tenth 30-microm-thick section. Psammoma bodies were observed in the IAC and around the labyrinthine portion of the facial nerve (FN), the geniculate ganglion of the FN, and the posterior ampullary nerve in the singular canal. The number of psammoma bodies increases with age. We believe that psammoma bodies are a normal finding of aging in the IAC. The compression of the FN by psammoma bodies in the labyrinthine portion of the facial canal and the distribution of numerous psammoma bodies surrounding the posterior ampullary nerve in the narrow singular canal raise the questions of the involvement of psammoma bodies in the FN and in vestibular dysfunction and the presence of psammoma bodies in the subarachnoid space.

Inflammatory response to chronic otitis media in DiGeorge syndrome: a case study using immunohistochemistry on archival temporal bone sections

Immunohistochemical analyses were conducted on archival celloidin-embedded human temporal bone sections from an 8-month-old boy with chronic otitis media and DiGeorge syndrome. We employed antigen retrieval methods with saturated sodium hydroxide-methanol solution, microwave incubation, and proteolytic treatment to demonstrate the distribution of T-lymphocytes, B-lymphocytes, macrophages, and intercellular adhesion molecule 1 (ICAM-1) expression in the middle ear. B-lymphocytes and macrophages were observed predominantly within the middle ear mucosa. T-lymphocytes were rare. Further, ICAM-1 was expressed in the vascular endothelium of the lamina propria, as well as infiltrating mononuclear cells. This suggests that the expression of ICAM-1 can be induced in the middle ear with otitis media, even if T-lymphocytes are depressed in a cell-mediated immunodeficiency disorder such as DiGeorge syndrome.

Postnatal development of Eustachian tube: a computer-aided 3-D reconstruction and measurement study

The postnatal development of the Eustachian tube (ET) and its surrounding structures was investigated by means of computer-aided three-dimensional (3-D) reconstruction methods in 13 normal human temporal bones, obtained from individuals 3 months to 71 years old. The cross-sectional area, width and height of the lumen in most of the cartilaginous portion of the ET were significantly smaller in children than in adults. In particular, there was a marked, age-associated difference in the shape of the lumen in the cartilaginous portion of the ET. In adults, the cross-sectional area of the lumen declined monotonically between a large opening at the pharyngeal orifice and the narrowest portion of the ET (near the border of the cartilaginous and junctional regions). In children, by contrast, the ET lumen was uniformly smaller over the first 80% of its length from the pharyngeal orifice. It is suggested that this immature morphology of the ET lumen may confer increased risk of developing otitis media during childhood.

Three-dimensional reconstruction and measurement study of human eustachian tube structures: a hypothesis of eustachian tube function

Histologic sections from nine temporal bones with eustachian tubes (ETs) attached were analyzed with a computer-aided three-dimensional reconstruction method to determine the curvature and tilt of the ET and the anatomic relationships between the medial lamina of the ET cartilage, the levator veli palatini muscle (LVPM), and Rosenmüller's fossa. It was found that the ET is convex superomedially and is tilted medially. The LVPM is located inferolateral to the inferior margin of the medial lamina of the anterior ET cartilage. The LVPM is inferior to the medial lamina of the posterior ET cartilage. These findings suggest that the LVPM opens the anterior cartilaginous portion of the ET by rotating the medial lamina with increased dimension of the muscle body when it contracts. Rosenmüller's fossa extends along the ET with rich lymphoid tissues as far as approximately one half the total length of the ET and very close to the skull base.

Histopathological features of a cochlear implant and otogenic meningitis in Mondini dysplasia

The temporal bones of a 6-year-old boy with a cochlear implant for profound hearing loss associated with Mondini dysplasia were studied histopathologically. Despite having severe Mondini dysplasia, he was able to detect sound with the implant. On histological examination of the temporal bone, he had more than 10000 spiral ganglion cells. Histopathological changes in the inner ear associated with the cochlear implant were minimal. Patients with severe Mondini dysplasia and profound hearing loss may, therefore, benefit from cochlear implantation. In the contralateral ear, the patient had suppurative labyrinthitis and meningitis associated with chronic otitis media. Histopathological evidence of inflammatory necrosis of the round window membrane was consistent with suppurative labyrinthitis secondary to otitis media.

Molecular and cellular pathology of Meniere's disease

The etiopathogenesis of Meniere's disease has remained controversial since the early 1900s. Many investigators have studied the molecular and cellular pathology of the inner ear in patients with this disorder. Three basic pathologic mechanisms have emerged; fibrosis of the endolymphatic sac and vestibular epithelia, altered glycoprotein metabolism, and immune-mediated inner ear disease. This article reviews the current understanding of these three basic pathologic processes.

Immunohistochemistry of lymphocytes and macrophages in human celloidin-embedded temporal bone sections with acute otitis media

Immunohistochemical analyses were used to investigate the distribution of lymphocytes and macrophages in routine human temporal bone sections obtained from a subject with acute suppurative otitis media. Primary antibodies specific for human CD3 and CD43 (T-lymphocytes), CD20 (B-lymphocytes), CD45 (leukocyte common antigen), and CD68 (macrophages) were used. As a pretreatment, the sections were soaked in antigen retrieval solution (saturated sodium hydroxide-methanol solution in methanol at a ratio of 1:3). A second antigen retrieval procedure (microwave treatment in 1% zinc sulfate) was also employed for identifying CD3-positive cells. Then the avidin-biotin-peroxidase complex technique was performed. Positive reactions to all antibodies but anti-CD68 were observed in the mucosa of the eustachian tube, tympanic cavity, and mastoid air cells. Particularly, cells positive to anti-CD3 or anti-CD43 were making a diffuse invasion upon the lamina propria. CD68-positive cells were scattered only in the effusion of mastoid air cells. These results suggest that the retrospective immunohistochemical study of archival temporal bone sections is a promising approach to investigate the pathogenesis of otitis media.

Narrowest (isthmus) portion of eustachian tube: a computer-aided three-dimensional reconstruction and measurement study

Nine normal human temporal bones from persons 16 to 88 years old were studied by computer aided three-dimensional reconstruction and measurement. The length of the eustachian tube (ET) lumen in three portions (from pharyngeal orifice to tympanic orifice: cartilaginous, junctional, and bony) averaged 23.6 +/- 4.3 mm, 3.0 +/- 1.9 mm, and 6.4 +/- 2.6 mm. The narrowest portion of the ET lumen was in the cartilaginous portion in all cases: 20.5 +/- 4.2 mm from the pharyngeal orifice and 3.1 +/- 1.6 mm from the pharyngeal margin of the junctional portion. The cross-sectional area of the narrowest portion was 0.65 +/- 0.2 mm2. The tendon of the tensor veli palatini muscle (TVPM) inserted into the lateral lamina in the narrowest portion of the ET lumen in five of nine cases. These results suggest that contraction of the TVPM opens the narrowest portion of the ET lumen to ventilate the middle ear and that this portion also plays a role in protecting the middle ear.

Postnatal change in angle between the tympanic annulus and surrounding structures. Computer-aided three-dimensional reconstruction study

Postnatal developmental relationships in human ears were studied by a computer-aided three-dimensional reconstruction and measurement method. We measured the angle, in reference to the horizontal plane, between the tympanic annulus, the oval window, and the internal auditory canal (IAC) in 20 normal temporal bones obtained from individuals between 1 day old and 76 years old. The horizontal plane was defined as the plane sloped 30 degrees infero-anteriorly from the plane of the horizontal canal in each specimen. The plane of the tympanic annulus changed from a nearly horizontal orientation (34.2 degrees from the horizontal plane) in neonates to a more vertical orientation (63.3 degrees from the horizontal plane) in adults. The tympanic annulus and oval window planes remained at the same angle to each other (11.9 degrees +/- 5.1 degrees) throughout postnatal development, as did the plane of the tympanic annulus and the IAC (68.6 degrees +/- 5.3 degrees). These findings have implications for ear surgeons, especially those operating on young children.

Developmental changes in folding of the human eustachian tube

Histologic sections of human temporal bone with Eustachian tube attached were examined to investigate the changes that occur in folding of the Eustachian tube (ET) as it develops postnatally. Study of 45 specimens from individuals aged 3 months to 88 years of death, including 5 cases with chronic otitis media (OM) with perforation and 5 with OM with effusion, showed that the folds in the tube decreased significantly as age increased up to 20 years, after which no significant change with age was found. These results suggest that folding in the ET is important to its function in infants and children. Folding provides a relatively greater surface area for the tube, allowing for a greater abundance of ciliated cells, which would promote clearance of the middle ear through the ET. Greater folding might also support the tube's protective function by keeping the lumen narrow.

Mucosa-associated lymphoid tissue in middle ear and Eustachian tube in children

The presence of mucosal lymphoid follicles with germinal centers, so called mucosa-associated lymphoid tissue (MALT), in the Eustachian tube (ET) and middle ear (ME) was investigated in 23 human temporal bones containing the entire ET obtained from 23 children, 3 months to 10 years old at death. Greater numbers of MALTs were found in specimens from children with otitis media (OM) than from those without OM. MALT showed a wedge-shaped distribution through the ME and ET: in all 3 specimens that had MALTs in the ME, these tissues were seen throughout the ET; in all 4 specimens with MALTs in the bony portion of the ET, these tissues were present both in the tympanic and pharyngeal portions of the cartilagines ET; all 7 specimens that had MALTs in the tympanic half of the cartilagines ET had MALTs in the pharyngeal portion of the cartilagines ET as well. Furthermore, MALTs were noted in the pharyngeal portion of the ET in more than half of the specimens without OM but in none of the MEs of specimens without OM. These results support the hypothesis that persistent and recurrent inflammation in the nasopharynx spreads through the ET to play a role in the pathogenesis of chronic OM in children.

Three-dimensional course of the vestibular aqueduct

Three-dimensional (3-D) reconstruction methods were employed to study the anatomy of the vestibular aqueducts (VAs) in ten postmortem temporal bone specimens obtained from ten individuals aged 4 months to 70 years at death. After reconstruction, the ten 3-D images of VAs were superimposed on one another and differences evaluated. The VA showed postnatal growth and variations in size and shape. However, the variations in angle at which the VA bends near the isthmus were not correlated with age. Furthermore, study of the superimposed images revealed that the 3-D course of the VA was essentially the same in individuals of all ages, despite its wide variability in size and shape. These results indicate that the basic course of the VA is determined before early infancy although the VA grows thereafter, suggesting that VA anomalies such as "large vestibular aqueduct syndrome" (in which the VA takes an abnormally straight and wide course) may be established prenatally.

Postnatal development of the internal auditory canal studied by computer-aided three-dimensional reconstruction and measurement

Postnatal development of the internal auditory canal (IAC) was investigated in 20 normal human temporal bones obtained from individuals 1 month to 72 years old. Computer-aided three-dimensional reconstruction and measurement of bones showed that the superior, inferior, anterior, and posterior walls of the IAC lengthen significantly from birth until about 10 years of age, with development mainly attributable to lengthening of the part of the IAC medial to the foramen singulare. The lengths of the part of the IAC lateral to the foramen singulare and of the transverse crest and Bill's bar did not appear to develop postnatally. The IAC diameter increased slightly at the porus for about the first year after birth, but not at the fundus or the middle portion of the canal. This finding was confirmed by studying the shape of the IAC. Postnatal increases in the volume of the IAC followed patterns similar to that of increases in length of studying the shape of the IAC. Postnatal increases in the volume of the IAC followed patterns similar to that of increases in length of the IAC walls. These results show that postnatally the IAC increases significantly in length until about 10 years of age and slightly in diameter until about 1 year of age, especially medial to the foramen singulare. This concentration of growth of the IAC medially implies that its postnatal development is mainly due to growth of the bone around the otic capsule, which has implications for IAC surgery.

Orientation for cochlear implant surgery in cases with round window obstruction: a computer reconstruction study

In order to improve cochlear implant surgery in patients with obstructed round windows, surgical orientations of the round window and scala tympani relative to the stapes footplate were examined in ten normal temporal bones using a computer-aided, three-dimensional reconstruction and measurement technique. The round window was found to be exactly inferior to the midpoint of the inferior margin of the stapes footplate in most cases. An optimal point on the promontory wall for drilling to reach the bottom of the scala tympani of the basal turn was found to lie approximately 1.5 mm anterolateral or anterolateral inferior to a point 3 mm inferior to the midpoint of the inferior margin of the stapes footplate. A combination of the transmeatal and facial recess approaches made it possible to consistently reach the scala tympani, and demonstrated that this approach was also applicable to patients with obstructed round windows.

Postnatal developmental changes in facial nerve morphology. Computer-aided 3-D reconstruction and measurement

Accurate measurements of the lengths and angles of the facial nerve were obtained in eight normal human temporal bones of varying ages from 7 days to 76 years. Measurements were made on serial histological sections, using computer-aided three-dimensional (3-D) reconstruction. The most noteworthy of the findings demonstrated that both the mastoid portion of the facial nerve and the segment of the facial nerve between the second genu and the divergence of the chorda tympani nerve lengthened with age. The mastoid segment lengthened more significantly than the latter, indicating the facial canal grows more than the facial nerve in its mastoid portion. This difference in growth rates results in the site of the chorda tympani nerve divergence shifting with age relative to the stylomastoid foramen.

Postnatal development of the vestibular aqueduct in relation to the internal auditory canal. Computer-aided three-dimensional reconstruction and measurement study

To investigate a possible developmental relationship between the internal auditory canal (IAC) and the vestibular aqueduct (VA), we made the following measurements in 10 normal temporal bones from individuals 4 months to 70 years of age at death, using a computer-aided three-dimensional reconstruction and measurement method: the volume of the VA, the length of the IAC, and the distance between the IAC and the external aperture of the VA. The degree of periaqueductal pneumatization was also assessed qualitatively by means of a light microscope. The three parameters increased postnatally in parallel with the development of the periaqueductal air cells, and all pairwise comparisons of these parameters showed a statistically significant correlation. Our results indicate that the IAC and VA develop synchronously and in parallel with the development of the periaqueductal air cells. We believe that an understanding of this relationship will be of help during surgery involving the IAC and VA, and may shed some light on the morphological features of Meniere's disease.

Localization of function in the eustachian tube: a hypothesis

This communication uses our recent quantitative morphometric studies to develop a hypothesis for localization of ventilatory, clearance, and protective functions in different portions of the eustachian tube (ET). We hypothesize that the ET roof is involved mainly with ventilation and that the ET floor is involved mainly with clearance, whereas both portions are involved with protection of the middle ear. The hypothesis states that 1) the cross-sectional shape of the ET lumen and the attachment of the tensor veli palatini muscle to the tip of the lateral lamina are important for ventilation, 2) the ciliated cells in the ET floor subserve clearance, 3) the richly distributed elastin in the hinge portion of the ET cartilage, Ostmann's fatty tissue, and rich mucosa-associated lymphoid tissue are protective, 4) the well-developed ET cartilage lateral lamina is important for both ventilation and protection, and 5) the rich mucosal folding, goblet cells, and glands subserve both clearance and protection. Finally, the utility of the hypothesis for elucidating anatomic factors in otitis media is discussed.

Anatomic relationships between Ostmann's fatty tissue and eustachian tube

To examine anatomic relationships between Ostmann's fatty tissue (OF) and the eustachian tube (ET), we evaluated serial histologic sections of 32 normal temporal bone-ET specimens and made a quantitative analysis of several measurements (height, width, and volume). We compared results in specimens from individuals in whom the ET was still developing (those 19 years and younger) to results in specimens from individuals with adult ETs (those older than 19). We found that 1) the main body of OF is located at the inferolateral aspect of the ET and 2) postnatally, OF grows in volume, mainly by an increase in height, so that OF maintains the same vertical relationship to the growing ET and does not increase in width. The former finding indicates that OF might exert static pressure on the ET not to open widely. The latter finding indicates that the relatively thicker mass of OF may narrow the ET in those with immature ETs. These results indicate a possible role for OF in ET function, which in turn has been implicated in otitis media with effusion.

Computer-aided 3-D reconstruction and measurement of the facial canal and facial nerve. I. Cross-sectional area and diameter: preliminary report

Using a computer-aided three-dimensional (3-D) reconstruction method, measurements were made at eight representative sites of diameters and the cross-sectional area of the facial canal, facial nerve, and the space between the canal and nerve. Materials used were serial histology sections of seven normal human temporal bones obtained from individuals of different ages. Two areas of decreased cross-sectional area of the facial canal were found: the proximal part of the labyrinthine portion and the middle part of the tympanic portion. These narrowings in the canal appeared to be correlated with decreased superior-inferior diameter of the facial canal in those portions, especially in adult temporal bones, and also with decreased cross-sectional area, both of the nerve and of the space between the canal and the nerve, in these portions. The developmental etiology of these narrowings is speculated on, and their possible relationship to Bell's palsy is discussed.

Facial nerve near the external auditory meatus in man: computer reconstruction study--preliminary report

The anatomy of the facial nerve relative to its intratemporal and extratemporal courses varies over time with developmental changes. Otologic and parotid surgery in infants and children demands detailed knowledge of the precise anatomy of the facial nerve with respect to the tympanic ring and external auditory canal. The authors analyzed this area using our three-dimensional (3-D) computer-aided reconstruction and measurement method studying the spatial relations of the facial nerve to the tympanic ring and stylomastoid foramen. Temporal bones from five normal individuals aged 36 gestational weeks, 3 months, 8 months, 4 years, and 17 years were retrieved from the temporal bone collection stored at the Elizabeth McCullough Knowles Otopathology Laboratory in Pittsburgh. Three-dimensional reconstruction of the facial nerve comparing the developmental anatomy across the various age groups provides the surgeon with the technical information necessary to address problems in this area.

Computer-aided three-dimensional reconstruction and measurement of facial canal dehiscence

Location, shape and dimensions of the dehiscence in the facial canal to the middle ear space were studied in 20 temporal bones obtained from 19 individuals aged 1 day to 72 years at death by using our computer reconstruction and measurement method. The most frequent site of dehiscence was the oval window area (70%), particularly in its posterior half and on the inferior to inferomedial aspect of the canal. The shape of the dehiscence tended to be oval in the oval window area, but rather irregular in the other areas. The dehiscence ranged from 0.4 to 2.64 mm in length, from 0.12 to 1.59 mm in width, and from 0.03 to 1.87 mm2 in surface area. Proximity of these dehiscences to the field of otological surgery is stressed.

Torsion of the human semicircular canals and its influence on their angular relationships

We used a computer-aided three-dimensional reconstruction and measurement method to measure torsion of the the semicircular canals (SCCs) in 10 normal human temporal bones from 10 individuals (3 months to 76 years old). Torsion of each SCC was measured as the angle between the "standard line" (the line connecting the ampullated and nonampullated ends of the SCC) and the plane of greatest SCC torsion. Torsion was greatest for the anterior SCC (16.4 +/- 3.6 degrees), followed by the lateral SCC (9.5 +/- 6.7 degrees) and the posterior SCC (8.5 +/- 4.2 degrees). The angles between the overall plane described by each SCC and the other SCCs between the anterior and lateral, the anterior and posterior, and the posterior and lateral SCCs were also measured and were found to be 78.7 +/- 10.0, 107.9 +/- 5.5, and 87.3 +/- 6.9 degrees, respectively. Finally the angles between the torsion plane of each SCC and the others were measured and found to be 92.6 +/- 15.4, 95.8 +/- 11.2, and 90.9 +/- 8.3 degrees, respectively. These results indicate that on average torsion in the SCCs tend to bring the angle between pairs of SCCs close to a right angle. This tendency to have a right angle between SCCs is thought to promote optimal vestibular function. Speculation is offered regarding the etiology of the greater torsion of the anterior SCC.

3-D anatomy of Scarpa's ganglion and surrounding structures

We reconstructed in three dimensions, and measured by a computer-aided method developed by us, Scarpa's ganglion and surrounding important anatomical structures in 7 normal human temporal bones obtained from 7 individuals aged 7 days to 72 years. We found that this ganglion is shaped like an hourglass and lies with its superior part directed anterosuperolaterally, and its inferior part posteroinferomedially; these two parts are connected by the isthmus ganglionaris. Although the dimensions of the parts of the ganglion varied, such a structure was distinguishable in all the specimens we studied. The volume of the ganglion was found to be relatively consistent in these postnatal specimens; although the width and height of the ganglion varied, they were inversely correlated with each other (linear regression analysis, p < 0.05). We did note, however, some postnatal increase in the distance from the ganglion to its neighboring structures. We also identified a significant correlation between the width of the ganglion and the length of the internal auditory canal and the distance from the ganglion to the vestibular endorgans in any given specimen (linear regression analysis, p < 0.05). These results suggest that although the volume of Scarpa's ganglion does not change after birth, its shape does change with the growth of the individual temporal bone.

Mucosal folds in human eustachian tube: a hypothesis regarding functional localization in the tube

Differences in the extent of mucosal folding in the superior versus the inferior half of the human eustachian tube (ET) lumen were studied by measuring, as it appeared in histologic cross section, the length of the mucosal margin in the pharyngeal portion, the midcartilaginous portion, the isthmus portion, and the osseous portion of each half of the ET in 16 normal ET temporal bone specimens from 16 individuals 12 to 70 years of age. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in all four portions (paired t test: pharyngeal portion t[15] = 3.59, p < .01; midcartilaginous portion t[15] = 3.52, p < .01; isthmus portion t[15] = 4.15, p < .01; osseous portion t[15] = 2.24, p < .05). These results indicate that the inferior half of the ET mucosa has more folds than the superior half, and that the surface area of the inferior half of the ET is larger than that of the superior half. This, together with the finding previously reported that secretory components of the ET such as glands and goblet cells are more richly distributed in the inferior (floor) portion than in the superior (roof) portion of the ET, may be related to the fact that the floor of the ET has an active role in clearance function. A hypothesis regarding localization of the ventilatory and clearance functions within the ET is proposed.

Mucosal folds of eustachian tube in young children

Differences in the extent of mucosal folding in the superior versus the inferior half of the human Eustachian tube (ET) were studied in young children by measuring the length of the mucosal margin and counting the number of mucosal folds, as they appeared in histological cross-sections, in the pharyngeal, midcartilaginous, isthmus, and osseous portions of each half of the ET in 12 normal ET/temporal bone specimens from 12 individuals aged 1 day to 2 years. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in the pharyngeal, midcartilaginous, and isthmus portions (paired t-test, pharyngeal portion: t[11] = 3.71, p < 0.01; midcartilaginous portion: t[11] = 4.52, p < 0.01; isthmus portion: t[11] = 3.40, p < 0.01). However, there was no significant difference between in the inferior half and in the superior half at the osseous portion. Also there were significantly more mucosal folds in the inferior half than in the superior half in all four portions (paired t-test, pharyngeal portion: t[11] = 3.46, p < 0.01; midcartilaginous portion: t[11] = 7.40, p < 0.01; isthmus portion: t[11] = 5.03, p < 0.01; osseous portion: t[11] = 4.49, p < 0.01). These results indicate that the surface area of the mucosa in the inferior half of the ET is larger than that of the superior half.(ABSTRACT TRUNCATED AT 250 WORDS)

Bony dehiscence between singular canal and round window niche

The incidence of bony dehiscence of the human singular canal was studied by examining 409 human temporal bones obtained from 300 individuals. Such a dehiscence was noted in three (0.7%) of the bones from three (1%) of the individuals, all male, aged 2, 6, and 76 years. All of these bony dehiscences were located between the round window niche and the cribrose area of the singular canal. The finding of a microfissure in the vicinity of the bony dehiscence in two of the three cases indicates that such dehiscences occur independently of microfissures. Although the incidence of bony dehiscences of the singular canal is small, these dehiscences appear to have considerable clinical significance in that they form a communication between the middle and inner ears or possibly between the middle ear and the cerebrospinal fluid space.

Facial canal dehiscence: histologic study and computer reconstruction

The incidence, location, shape, and dimensions of dehiscences in the facial canal to the middle ear space were studied in 160 temporal bones obtained from 129 individuals 24 gestational weeks to 109 years of age at death by means of light microscopy and our computer reconstruction and measurement method. Dehiscences were observed in 95 of the 129 individuals (74%) and in 119 of the 160 bones (74%). The incidence was found to be quite high among fetuses and newborns, lowest in individuals in their twenties and then again quite high in the geriatric population (chi 2 test, chi 2 = 5.45 and 4.41, p < .05). The most frequent site of dehiscence was the oval window area, particularly in its posterior half (57% of all ears) on the inferior to inferomedial aspects of the canal; these dehiscences were clearly demonstrated in reconstructed images. The incidence of dehiscence in the area of the cochleariform process was 16%, and all these dehiscences were on the lateral to superolateral aspect of the canal. The second genu area and the mastoid portion were sites of dehiscence in 21% and 18%, respectively, of specimens; more than half of the dehiscences in the second genu area and mastoid portion were on the lateral to anterolateral and posterior aspects of the facial canal, respectively. The shape of the dehiscence tended to be oval in the oval window area, but rather irregular in the other areas. The dehiscences ranged from 0.4 to 2.64 mm in length, from 0.12 to 1.59 mm in width, and from 0.03 to 1.87 mm2 in surface area. The proximity of these dehiscences to the field of otologic surgery is stressed.

Three-dimensional surgical anatomy for stapes surgery computer-aided reconstruction and measurement

To define anatomical relationships relevant to stapes surgery, computer-aided three-dimensional reconstruction and measurement were performed on nine normal temporal bones. The mean distance from the inferior portion of the long process of the incus to the center of the oval window was 3.80 mm. The shortest distance from the center of the oval window to the utricular macula, saccular membrane, and macula averaged 1.37, 1.60, and 2.13 mm. Surgery directed posteromedial-superior from the oval window was found to be most dangerous because it would come so close to the utricular macula; a posteromedial-inferior approach was found to be safest. The distance from the inferior margin of the oval window inferiorly to the cochlear duct in the hook portion ranged between 0.58 and 1.29 mm, suggesting that when a drill hole is made on the inferior margin of the oval window to lift up a depressed stapes footplate, the hole should not be greater than 0.5 mm in diameter.

Histopathology of tubotympanum of children with otitis media treated with ventilation tubes

We studied histopathologically the middle ear (ME) and eustachian tube (ET) in 12 temporal bones from eight children who had had otitis media with effusion that had been treated with ventilation tubes (VTs) for 3 weeks to 11 months. In the ME, 1) only a minimal amount of effusion was seen in most of the ears treated for 3 months or longer, 2) the severity of submucosal inflammation almost paralleled the amount of effusion, 3) the amount of granulation tissue on the tympanic membrane at the site of VT insertion also seemed to parallel the degree of ME inflammation, and 4) epidermal ingrowth was seen in both of the two ears treated with VTs for 10 and 11 months. Pathologic findings in the ET were generally more severe than those in the ME, but tended to decrease with longer VT therapy. In two ears with VTs obstructed by inflammatory granulomatous tissue, the entire ME cavity was filled with effusion, and dense effusion plugged the bony portion of the ET. The results of this study indicate that 3 to 11 months of treatment with a VT is effective for reversing the ME effusion and for reducing inflammation in the ME. Some inflammation may be left in the ET, however, even with 11 months of VT therapy, and epithelial ingrowth should be watched for when VT therapy lasts 10 months or longer. Despite the fact that most of our temporal bones were from infants and children who had a variety of systemic diseases or disorders and in whom their terminal event might have contributed to our findings, we consider these temporal bones to be informative.

Computer-aided three-dimensional measurement of the human vestibular apparatus

Using a computer-aided three-dimensional reconstruction and measurement method, 12 measurements were made to determine the dimensions of the maculae, cristae ampullares, and semicircular canals in 18 temporal bones from nine pairs of age-matched male and female individuals (1 day to 76 years old). The surface areas of the utricular and saccular maculae were significantly larger in male than in female specimens (two-way analysis of variance, F = 9.00, df = 1, p less than 0.01; F = 4.57, df = 1, p less than 0.05, respectively). The width of the utricular macula and the length of the saccular macula were also significantly greater in male than in female specimens (two-way analysis of variance, F = 5.17, df = 1, p less than 0.05; F = 4.33, df = 1, p less than 0.05, respectively). Finally, the three semicircular canals were larger in diameter in male vs. female specimens; this difference was statistically significant for the superior semicircular canal (two-way analysis of variance, F = 10.74, df = 1, p less than 0.01). By contrast, none of these dimensions of those vestibular structures showed any significant change in size with advancing postnatal age. We propose from these findings that there appears to be sexual dimorphism in the vestibular apparatus.

Three-dimensional anatomy of human Scarpa's ganglion

Using a computer-aided three-dimensional reconstruction and measurement method, the authors studied the shape and dimensions of Scarpa's ganglion and interrelations of the ganglion to nearby important anatomical structures in 10 normal human temporal bones obtained from 10 individuals of different ages (12 gestational weeks to 72 years). In the postnatal cases, Scarpa's ganglion was shaped like a distorted hourglass. Although the shape of the ganglion varied somewhat among specimens, a superior division, inferior division, and isthmus ganglionaris were distinguishable in each case. Volume of the ganglion was relatively consistent after birth, so that width and height of the ganglion were inversely correlated with each other (linear regression analysis, P less than .05). There seemed to be, however, a possible postnatal increase in the distances from the ganglion to neighboring structures and in the length of the internal auditory canal; these increases were probably the result of postnatal growth of the temporal bone. Moreover, the width of the ganglion in any single specimen was found to correlate significantly positively with the distances from the ganglion to the vestibular end-organs and the length of the internal auditory canal in that specimen (linear regression analysis, P less than .01). This finding suggests that Scarpa's ganglion may be elongated secondary to the elongation of the vestibular nerve due to the growth of the temporal bone. In fetuses, each portion of the ganglion was less clearly identifiable than that portion in postnatal cases. The dimensions of Scarpa's ganglion were found to have reached maturity around the time of birth.

Distributions of eustachian tube goblet cells and glands in children with and without otitis media

The distributions of the goblet cells and submucosal glands in eustachian tubes (ETs) from children with or without otitis media (OM) were studied. From 12 temporal bone-ET specimens obtained from children 1 to 7 years old at death, representative vertically cut histology sections were selected, stained with periodic acid-Schiff-Alcian blue and hematoxylin, and studied by light microscopy. In children without OM, the density of the goblet cells was significantly lower in the roof than in the floor of the ET and was highest in the midcartilaginous portion; glands were most richly distributed near the pharyngeal orifice, and became less densely distributed toward the tympanic portion. In children with OM, the density of the goblet cells was significantly higher both in the roof and floor portions, and the glands were more richly distributed than in the ETs of children without OM. The possibility that the observed increase in ET secretory components in children with OM impairs the passage of air through these tubes is discussed.