Isamu Sando

Localization, Frequency, and Severity of Endolymphatic Hydrops and the Pathology of the Labyrinthine Membrane in Meniere's Disease

The localization, frequency, and severity of endolymphatic hydrops in 22 temporal bones of 16 individuals with Menieres disease were studied histopathologically. Endolymphatic hydrops was more often observed in the pars inferior (22/22) than in the pars superior (13/22) of the temporal bone, and severe hydrops was observed most frequently in the saccule, followed by the cochlea, the utricle, and the three semicircular canals. In the cochlea, the most severe hydrops was observed in the apical turn, followed by the hook portion, the middle turn, and the basal turn. Clinically interesting observations regarding endolymphatic hydrops included bulging into the perilymphatic space of the vestibule. In 17 of 22 bones the saccular membrane bulged into the vestibule laterally and was attached to the footplate of the stapes. In two of 22 bones, Reissners membrane in the hook portion of the basal turn of the cochlea bulged superiorly into the vestibule, occupying most of the perilymphatic space of the vestibule.

Sexual Dimorphism and Development of the Human Cochlea: Computer 3-D Measurement

The length of the cochlear turns was measured in 9 pairs of temporal bones from age-matched male and female individuals (1 day to 76 years old), using a computer-aided three-dimensional reconstruction and measurement method. The mean cochlear length was significantly longer (Two-way analysis of variance, F = 31.87, d.f. = 1, p less than 0.01) in males (37.1 +/- 1.6 mm) than in females (32.3 +/- 1.8 mm), whereas it did not vary with postnatal age in either sex. Sexually dimorphic cochlear length may pose a new issue in auditory physiology in man. The lack of postnatal elongation also indicates that length of the cochlea becomes close to its maximum during fetal life.

Computer-aided three-dimensional reconstruction: a method of measuring temporal bone structures including the length of the cochlea.

To visualize the three-dimensional (3-D) shapes of structures in the temporal bone from histologic sections, we developed computer software to create computer-generated 3-D images from two-dimensional (2-D) materials. Using those images, we have been able to measure these structures in three dimensions. This means that quantitative 3-D measurements can be performed regardless of the angle at which the specimen was cut. This report describes this method for 3-D reconstruction and measurement and discusses its implications. For instance, in addition to showing the 3-D shape of the cochlea from different angles, we have been able to measure the length of the cochlea and have shown that measurements made by use of the conventional 2-D graphic reconstruction method can be distorted considerably by variations in cutting angle of the specimen.

A method for the histopathological analysis of the temporal bone and the eustachian tube and its accessory structures.

A very important contribution to the study of otitis media, one of the diseases most often seen in pediatric patients, is the collection processing, and study of the specimens of the temporal bone and the entire eustachian tube. During the last few years, we have collected, processed, and studied 100 such specimens, and through these experiences our technique has become refined. We now have some important suggestions for otologists interested in the histological study of otitis media as well as in the pathology of the eustachian tube and its relation to middle ear abnormalities. This report details the most successful method for the study of eustachian tube abnormalities and their relationship to middle ear effusion.

Endolymphatic Duct and Sac in Patients with Meniere's Disease A Temporal Bone Histopathological Study

The endolymphatic ducts and sacs of 25 temporal bones with idiopathic endolymphatic hydrops from individuals with Menieres disease were studied and compared with the same number of control bones without endolymphatic hydrops from individuals with no premortem history of otologic disease. The control bones were selected so that the sizes of their vestibular aqueducts matched those temporal bones from individuals with Menieres disease. The endolymphatic ducts and sacs of all bones were studied by the medial view-graphic reconstruction method and or histological observation under a light microscope. In the endolymphatic duct and sac of many of the temporal bones from patients with Menieres disease were noted a diminution of the width of the endolymphatic duct in its isthmus portion, an increase in the area of the collapsed lumen of the endolymphatic sac, fibrotic changes in the perisaccular loose connective tissue, and an increase in the quantity of intraluminal eosinophilic material. The frequencies with which these pathological findings were noted in bones from individuals with Menieres disease and in control bones were statistically significantly different. No significant differences were observed under light microscopic study between these two groups with regard to the condition of the epithelial cells, the degree of rugosity of the endolymphatic sac, or the appearance of melanin-like pigmentation of hyalinization in the perisaccular connective tissue.

The vestibular aqueduct in patients with Meniere's disease. A temporal bone histopathological investigation.

Menieres disease (idiopathic endolymphatic hydrops) was studied in human temporal bone histology sections. Measurements were made of the area, length, width, angle, position, and external aperture of the vestibular aqueduct in 27 temporal bones of individuals with this disease. These measurements were compared with measurements of the same parameters in 88 normal temporal bones. It was found that small vestibular aqueducts were more often observed in the temporal bones of patients with Menieres disease than in temporal bones from individuals without this disorder. The difference in size of the vestibular aqueduct in bones with hydrops and normal bones was statistically significant.

Hearing Loss in Renal Disease: Clinical and Pathological Studies

Ninety-one of 224 chronic renal patients, most of them hemodialysis and/or transplant patients, had sensorineural loss: 11% noise exposure; 7% genetic; 22% due to multiple factors, including ototoxicity; 41% with hearing loss and ototoxic drug exposure, (but one-fourth had had insufficient drugs to cause hearing loss) and 11% were of unknown etiology. Hearing loss and normal hearing patients exposed to ototoxicity or multiple factors were similar in all parameters but hearing loss. Ten temporal bone cases are described, two from patients with hearing loss of unknown origin. One showed cochlear hydrops, fibrous tissue proliferation in cochlear perilymphatic spaces, Cortis organ degeneration, displaced tectorial membrane and probable metastatic calcification in the stria vascularis. The other case showed hair cell loss. Three patients had had ototoxic drugs; one bad hair cell loss and tectorial membrane abnormalities; one had hair cell loss and metastatic strial calcification; one was normal. One patient had pus in both internal auditory canals. Another bad otosclerotic focus without stapes fixation. Three were normal. We do not yet recognize pathology typical of hearing loss of severe renal disease. Findings seem to fall into two broad categories: those of known entities and those of obscure etiology.

Insertion of the Tensor Veli Palatini Muscle into the Eustachian Tube Cartilage in Cleft Palate Cases

Differences in insertion of the tensor veli palatini muscle (TVPM) into the lateral lamina of the eustachian tube (ET) cartilage between cleft palate (CP) cases and controls were investigated histologically. Thirty temporal bones with entire ETs were studied: 10 from individuals with CP and 20 controls. The ratio of the length of the ET cartilage with insertion of the TVPM to its total length from the nasopharyngeal end to near the tubal isthmus was calculated in all 30 cases. In all 20 controls, but in only 6 of 10 CP cases, the TVPM inserted into the lateral lamina of the ET cartilage at its tip portion (χ2 test, p < .025). The ratio was significantly smaller in CP cases (0.178 ± 0.172) than in controls (0.419 ± 0.120) (t = 4.305, p < .001). We believe that abnormal insertion of the TVPM into the ET cartilage is one of the causes of the functional obstruction of the ET that contributes to the frequent bouts of otitis media experienced by those with cleft palate.

Computer-Aided Three-Dimensional Reconstruction and Measurement of the Vestibular End-Organs

It is very valuable for temporal bone morphologists to be able to recognize temporal bone serial sections in three dimensions and to be able to measure temporal bone structures three-dimensionally. We can now do 3-dimensional reconstruction to visualize the structures of vestibular endorgans (utricular and saccular maculae) and measure these endorgans in space by means of a small computer system and software that we developed. As well as obtaining the dimensions—such as length and area—of the utricular and saccular maculae, we also found that (1) most of the utricular macula lies in one plane, which is the same as the plane of the lateral semicircular canal, (2) the saccular macula is shaped like part of a sphere, and (3) the angle between the two maculae is less than a right angle. Such knowledge is indispensable to the evaluation of the function of the utricular and saccular maculae.)

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.