Attic aeration in temporal bones from children with recurring otitis media: tympanostomy tubes did not cure disease in Prussak's space.

HYPOTHESIS: Blockage of the aeration pathways to the attic may cause circumscribed or widespread alterations that are difficult to diagnose clinically. The narrow route via the posterior pouch to Prussak's space is especially vulnerable to obstruction in recurring otitis media. BACKGROUND: Recent studies of the epitympanic diaphragm and compartments have clarified the anatomy of the attic aeration and drainage pathways and emphasized the role of their patency in the healing process of middle ear infections. In neonatal otitis media, the amniotic fluid cellular content (AFCC) has proved to be a good indicator in outlining the areas where inflammation products concentrate, possibly causing early blockage of ventilation. METHODS: Twenty-eight temporal bones from 14 children were studied; 4 of these children had experienced bilateral recurring otitis media. In the latter group, 1 ear was studied by microdissection and the other by serial sectioning. RESULTS: Prussak's space was involved in all 4 pairs of bones and either contained thick mucus, contained secretion in the process of organization, or was obliterated. The tympanic isthmus was fully obstructed in 1, partially blocked in 2, and open in 5 specimens. CONCLUSIONS: If a thick mature connective tissue mass develops under the epidermal layer of Shrapnell's membrane during an obliteration process of Prussak's space, the condition may stay stable and benign. Severe retraction of Shrapnell's membrane represents a likely forerunner of a retraction pocket cholesteatoma. Systematic otomicroscopy allows early detection, and cure can be achieved by minor surgery. In some children, despite the treatment of recurring otitis media with ventilation tubes, the attic and mastoid can be extensively involved, necessitating atticomastoidectomy and the creation of new pathways for attic aeration.

Epitympanic compartment surgical considerations: reevaluation.

The epitympanic compartments and the anatomy of the atticotympanic diaphragm were examined in a pair of serially sectioned temporal bones with secretory otitis media and chronic otitis media, respectively. Findings confirmed reports of 19th century scientists in that Prussak's space has a wide connection to the mesotympanum through the posterior pouch of Tröltsch and may have an additional narrow passage in its roof to the lateral malleal space. The lateral incudomalleal fold regularly separates the upper lateral attic from the lower lateral attic and the mesotympanum. The medial incudal fold as a rule is atrophic already at birth. The anterior tympanic isthmus thus extends from the tensor tympani tendon to the posterior incudal ligament and is the main passage for epitympanic and mastoid aeration. Opening(s) in the tensor fold, when present, are also important. In some ears, the posterior tympanic isthmus may form an auxiliary narrow route for aeration via the incudal fossa. The isthmi may be blocked by middle ear infection, which can lead to chronic mastoid and attic disease. Pathways for cholesteatoma spread in the epitympanum are discussed.

Cochlear vascular pathology and hydrops in otosclerosis.

Three ears with otosclerosis were found incidentally in a series of human temporal bones examined to evaluate cochlear sensorineural degeneration. Otosclerosis was identified with microdissection, surface preparation technique and transmission electron microscopy. Vascular abnormalities were present in all ears, and otosclerosis involved the cochlear endosteum extensively, mainly in the scala tympani of the basal turn. In the scala tympani of the lower half of the basal turn, shunts had formed so that venules deviated abruptly from their normal radiating course towards the spiral vein, left the scala and entered into otosclerotic foci. There was a marked loss of radiating venules in areas where otosclerosis affected the endosteum of the scala. In the pair of bones capillaries in the stria vascularis were extremely dilated, the widest being 80 microns in diameter. The third single bone from a patient with Meniere's disease had severe cochleo-saccular hydrops. Ten serially sectioned temporal bones with known otosclerosis were reviewed. Two of the bones, one of which had cochleo-saccular hydrops, displayed vascular shunts in the scala tympani and enormously dilated strial capillaries with a maximum diameter of 139 microns.

Morphological features of human Reissner's membrane.

Light and electromicroscopic investigations of Reissner's membrane were undertaken on 10 cochleae from 6 patients with normal hearing for their age. The membrane consisted of two layers, an epithelium and a mesothelium separated by a basement membrane. The mesothelium was formed by a single thin layer which was intermittently discontinuous. The melanocytes were localized on the mesothelial side of the basement membrane. Their numbers was 2-4 times greater in the upper half of the basal turn and in the middle turn than elsewhere. The epithelium was much thicker and had more irregular features than the mesothelium. It was composed of two types of epithelial cells, flat and rounded. The flat cells were more regular in shape than the rounded cells and they were mainly distributed in the middle and apical turns. Judging from their structure they were in a resting state. The rounded cells covered a smaller area than the flat ones and had numerous microvilli. They assumed three different shapes, cuboidal, spindle-form and spherical and were arranged in four different patterns, namely bands, strands, whorls and clusters. The rounded cells were the most active according to the composition of the cytoplasm and dominated the cell population in the hook and the lower half of the basal turn where the age-related sensorineural degeneration is most apparent.

Human Reissner's membrane in patients with age-related normal hearing and with sensorineural hearing loss.

Morphological features of Reissner's membrane were investigated in 6 patients with age-related normal hearing (ARNH) and in 4 with sensorineural hearing loss (SNHL) stemming from various causes. The membrane consisted of an epithelium, a basement membrane and a mesothelium with melanocytes. There were two major forms of epithelial cells: flat and rounded. In all specimens, the rounded cells formed whorls, clusters, strands and bands. The bands were wider and the whorls larger in the basal turn and decreased gradually in size toward the apex. The number of melanocytes was 2-4 times higher in both the upper half of the basal turn and the lower half of the middle turn than in the rest of the turns. In specimens from patients with SNHL, whorls and clusters were both more numerous and larger, and the number of melanocytes was higher in the upper half of the middle turn and in the apical turn than that in the ARNH group. Ultrastructural examination of epithelial and mesothelial cells as well as of melanocytes showed more pronounced cellular degeneration in patients with SNHL than in those with ARNH. A possible correlation between structural alterations of Reissner's membrane and sensorineural degeneration is discussed.

Multicentre evaluation of the temporal bones obtained from a patient with suspected Menière's disease.

A multicentre study of the inner ears of an 88-year-old patient with vertiginous spells and severe hearing loss in the left ear was performed, employing regular and block surface preparations, light and electron microscopy with qualitative and quantitative evaluation of the cochlear and vestibular nerves. There was severe hydrops of the left cochlea and saccule. Reissner's membrane extended into the vestibule and herniated into the perilymphatic space of the non-ampullated end of the horizontal canal. Furthermore, the short canal connecting the posterior ampulla with the utricle had a small, exceedingly thin balloon-like expansion. Only slight hydrops limited to the cochlea was found in the right ear. Sensorineural degeneration was much more pronounced in the left cochlea than in the right. The number of cochlear and vestibular nerve fibres was greatly reduced in the left ear where more fibres with degenerative changes were present. In both specimens the number of myelinated nerve fibres in osseous spiral lamina was smaller than that in the cochlear nerve in the internal auditory canal. Changes occurred in the endolymphatic sacs but were considered non-specific. In this case severe, apparently progressive hydrops and sensorineural degeneration, characteristic of Menière's disease, were associated with atypical onset of clinical symptoms at a late age.

Morphometric analysis of the cochlear nerve in man.

Fiber diameters were analyzed in the meatal segment of the cochlear nerve from 7 temporal bones obtained from 7 patients. Two patients had normal hearing for their age. Two had sustained noise exposure and one had presbyacusis of predominantly neural type. The cochleae displayed characteristic degeneration patterns. The other two manifested hearing loss of unspecified type. The fiber diameters ranged from 0.5 to 11 microns. The diameter distribution was unimodal in all seven nerves. The means of the diameters ranged from 4.2 to 5.5 microns. They were significantly different between patients with age-related normal hearing on the one hand and patients with noise induced hearing loss and neural presbyacusis on the other. The findings are discussed in relation to changes in nerve conduction speed and hearing loss; a possible correlation between the fiber diameter distribution and the tonotopical arrangement of the cochlea is suggested.

Surgical anatomy of the internal auditory canal. A temporal bone dissection study.

The suboccipital fossa approach to the fundus of the internal auditory canal (IAC) at acoustic neurinoma surgery was investigated in 32 temporal bones. A microdissection was done under the operating microscope in a specially constructed holder so that the surgeon's exposure and angles of view through the craniotomy were mimicked. It was possible to obtain an unobstructed view of the transverse crest and the vestibular nerves in all specimens without the bony labyrinth being opened in the process. A prerequisite was that, as the posterior wall of the IAC was removed, drilling did not extend lateral to a line running through the midpoint of the craniotomy to the transverse crest. The distances of major structures from the posterior and superior pyramid surface were measured, using a special impression technique that made it possible to measure the thickness of the bony layer removed.

Quantitative analysis of cochlear sensory cells and neuronal elements in man.

The myelinated radial fibres in the osseous spiral lamina and the myelinated fibres in the cochlear nerve in the internal auditory canal as well as the sensory cells were counted in cochleae from 15 dissected temporal bones from 8 patients. Light microscopy was carried out on semithin sections of epoxy resin embedded tissue. Audiometry had been performed within 6 months prior to death. Three patients had normal hearing for their age group, 2 had slight presbyacusis and the remaining 3 had sustained noise injury. All specimens clearly had fewer fibres in the spiral lamina than in the internal auditory canal. The cochleae from patients with normal hearing for their age group had a difference in the nerve fibre counts of up to 34%. A case of sensorineural presbyacusis showed 31%, and a case of neural presbyacusis, 47% difference. The greatest difference was found in a case of acoustic trauma, the range in this group being between 25% and 55%. The lower the number of fibres in the spiral lamina, the greater was the difference in all but two specimens. A slow retrograde degeneration, i.e. beginning in the peripheral process of the cochlear nerve, could be an explanation for these findings.

Ultrastructural aspects of the human peripheral vestibular system.

The sensory epithelia from the membranous labyrinths of 4 patients were examined by transmission electron microscopy. The distribution ratio of type 1 to type 2 cells was recorded, compared for each sensory area and correlated with age. An ultrastructural assessment confirmed generalized patterns consistent with autolytic and preparation artefact, viz. calyceal dilatation, cytoplasmic protrusions and some sensory hair loss. More specific features, i.e. lipofuscin accumulation, membrane-bound inclusions and neural degeneration were consistent with pre-mortem pathological change. In 2 patients, total nerve fibre counts of 15,766 and 19,741 were obtained. Total fibre counts correlated with the sensory cell density of the innervated areas. Differential counts of the superior and inferior vestibular nerves suggested that there was a reduced number of fibres in the superior division of both patients, in comparison with established normative data. Morphometric analysis of the constituent fibre diameters revealed a skewed distribution with a modal value of 6 microns for both patients.

Observations on the pattern of sensorineural degeneration in the human cochlea.

Cochlear sensory and neural degeneration was examined in nine pairs of human temporal bones fixed by perilymphatic perfusion, using phase-contrast and electron microscopy. Four pairs, three from females, had only slight sensorineural degeneration, limited to the very basal end of the cochlea. A predominantly neural degeneration was identified in a 54-year-old male. The process was bilateral, asymmetrical, uneven, and involved the entire length of the cochlea with several circumscribed areas of severe nerve degeneration. One case had mild, diffuse sensorineural degeneration in the lower half of the basal turn characteristic of presbyacusis. The other three pairs, all from males, revealed sensorineural degeneration patterns associated with noise injury and were remarkably similar to or almost identical with cochleas described previously. There was a good correlation between the presence of supporting cells and the survival of nerve fibres in the osseous spiral lamina in the corresponding area. In one cochlea, however, the degeneration of only inner hair cells in a small area was associated with complete nerve degeneration in the corresponding sector of the spiral lamina. Giant cilia were frequently seen in the apical turn.

The Otorhinolaryngology Department in Helsinki: organization and otologic research.

The organization and the otologic research in the Otorhinolaryngology Department of the University of Helsinki are described. The department has 4 surgical wards, each with 22 beds, and a new surgical wing with 6 full-sized operating rooms. The ear research is centered on middle ear histopathology and immunology, focusing especially on secretory and chronic otitis media. There is an audiological and vestibular unit, the latter is expanding rapidly. Acoustic neuroma surgery is performed as team work with a neurosurgeon. The department takes part in a cochlear implant and Audiant prosthesis program.

Ceramic prostheses used as a columella.

Ceramic stems, their lateral end capped with a modelled ossicle, or ceramic prostheses manufactured with a cap-shaped head were used as a columella from the stapes footplate to the tympanic membrane or a fascia graft in 41 ears operated on during 1982-1985. Six ears had no membrane perforations and no severe disease of the tympanic mucosa. Twelve ears underwent primary operations for cholesteatoma and 23 ears had revision surgery. Good hearing improvement occurred in well-aerated ears while hearing in ears with extensive tympanic disease did not improve after surgery. No tissue reactions to the ceramic prosthesis were observed and no prosthesis was extruded. Ceramic can be regarded as an acceptable alternative to bone for columella grafts used in surgery for chronic middle ear disease when the stapes superstructure is missing.

Hair cell distributions in the normal human cochlea. A report of a European working group.

Cochlear hair cell counts from individuals who had clinically normal hearing prior to their death have been plotted for various age bands as a function of the number of hair cells per millimetre against their position in the cochlea. Position has been expressed as the distance of that observation of hair cell density from the base of the cochlea, divided by the total length of the cochlea, thereby giving a proportional representation of the cochlea in the range of 0.0 to 1.0 with 20 subdivisions of 0.05. There is an age-related decrease in the number of hair cells in the normal population, and this is more marked for the outer hair cells.

The species-specific nature of the ototoxicity of dihydrostreptomycin in the patas monkey.

The remarkable susceptibility of the inner ear of the patas monkey (Erythrocebus patas) to the ototoxic action of dihydrostreptomycin (DHSM) (and streptomycin (SM)) is well established in this paper and affords a rare example of a species-specific reaction to a restricted class of compounds within the aminoglycoside group of antibiotics. In a series of experiments, behavioral and morphological observations together provided the following profile of DHSM ototoxicity in the patas monkey: Sudden onset of hearing loss beginning after 7-9 weeks of treatment; Substantial, though often partial, hearing impairment beginning at the high frequencies and progressing with or without continued treatment to the low frequencies; In the inner ear, a corresponding and selective loss of nerve fibers and of outer hair cells, relative to inner hair cells, beginning in the base of the cochlea and proceeding toward the apex; Continued and progressive loss of hearing for several months after cessation of drug treatment; and Non-auditory effects in some animals on the kidney and vestibular system. Results from control experiments confirmed this special relationship between the patas monkey and DHSM: Other nonhuman primates (macaques and vervet monkeys) were essentially unaffected by DHSM; The patas showed no equivalent sensitivity to other aminoglycosides such as kanamycin or to other forms of ototraumatic insult such as intense noise.

Preservation of hearing after removal of the membranous canal with a cholesteatoma.

Normal cochlear function was preserved in a patient after excision of the membranous canal from a huge fistula at revision surgery eight years after the primary procedure. A recurrent cholesteatoma had eroded the entire prominence of the horizontal canal and surrounded its membranous portion. The cholesteatoma, including the membranous canal, was removed in a one-stage procedure. The open ends of the bony canal were sealed with a fascia soaked in fibrin glue. After initial dizziness and severely reduced hearing, the patient quickly recovered, with normal bone conduction and a stable 30-dB hearing level by air conduction. The lumen of the membranous canal was patent, and only the ampullar end was atretic. Presumably, the fistula became separated from fluid spaces by formation of perilymphatic partitions and by collapse of the membranous labyrinth adjacent to the fistula.

Large cholesterol granuloma cysts in the mastoid. Clinical and histopathologic findings.

Large cholesterol cysts were found in revision surgery in six patients with previous ear surgery one to 28 years ago. The cysts mimicked brain herniation in open cavities, filled the mastoid and ear canal in closed cavities, or caused postauricular swelling. Bone around the cysts was soft and granulomatous. Secretory cells were scarce in the epithelial lining of the lumen, but subepithelial glands were frequent. Cholesterol granulomas and hemosiderin-laden macrophages were present inside the wall. The cyst lining and the glands under it showed cytokeratin staining typical for simple and glandular epithelia. Antiprekeratin antibodies showed no decoration of the lining but reacted positively with the meatal skin. These findings prove that respiratory-type epithelium separated from an aerated middle ear does not undergo changes into keratin-forming epithelium.

Perivascular demyelinization of cochlear neurons in two neonates.

Localized perivascular demyelinization of the peripheral processes of cochlear neurons was observed in surface preparations of the osseous spiral lamina in two neonates, one a premature infant with erythroblastosis fetalis, the other a full-term infant with cyanotic congenital heart disease. In both cases the cause of the demyelinization was unknown. Both infants had severe edema as a result of congestive heart failure and anoxia. The serum bilirubin level in the erythroblastotic child appeared too low to have caused injury to the nerve fibers. The demyelinization was most striking in the lower half of the basal turn. It was observed only in the immediate vicinity of meandering stretches of capillaries as they crossed the nerve fibers. In the premature infant there was hair cell loss throughout the cochlea; in the other there was no hair cell loss, but a malformed labyrinth of the Mondini type.

A re-examination of otoconia from the Shaker mouse.

We have studied saccular and utricular otoconia from Shaker-1 and Shaker-2 mice by X-ray diffraction and scanning electron microscopy. In contrast to previous reports, we found that the crystals were composed of calcite rather than polycrystalline hydroxylapatite. These crystals were indistinguishable mineralogically and morphologically from normal mouse otoconia. The reported occurrence of hydroxylapatite otoconia in the Shaker mouse is probably false.