Inner ear anomalies in two cases of trisomy 18

Two cases of trisomy 18 in which temporal bone defects were limited to the inner ears are described. Several abnormalities were present that have not been described previously in this syndrome. The first case involved a 1-month-old female infant who died of congenital heart defects. Cochlear nerve fibers were absent on the left side, with near-normal innervation on the right. Although the organ of Corti was present bilaterally, some of the outer hair cells were deformed, having small rounded cell bodies unsupported by Deiters' cells. On the right, similar abnormal cells were found in the tunnel of Corti. Vestibular defects in this case included reduced nerve supply of the left saccular macula, cysts in the superior and posterior cristae, and absence of the utriculoendolymphatic valve. The second case involved a newborn male infant with multiple congenital anomalies. The major cochlear defect was a deformity of the stria vascularis. In the lower apical turn, the stria was adherent to Reissner's membrane and extended beneath it into scala media. Large capillaries, which ran freely suspended in scala vestibuli, entered the upper portion of the stria. Severe atresia of the lateral and posterior semicircular ducts was found in the vestibular apparatus.

Temporal bone pathology in congenital anomalies of the oval window and the facial nerve

Temporal bones of six infants with congenital ear anomalies were examined for abnormalities of the oval window and facial nerve. These temporal bones were classified into two groups according to the degree of malformation: group A, those with atresia or absence of the oval window; and, group B, those with hypoplasia of the stapes and annular ligament. Group A, consisting of five ears, were associated with severe middle ear anomalies such as the abnormal course of the facial nerve and absence of the stapes. In group B, consisting of seven ears, the stapes were present and the facial nerve presented minor anomalies such as obtuse angulation at the first genu, central migration of the geniculate ganglion cells, ectopic muscles and a wide bony dehiscence of the facial canal around the oval window. Probable origin of the anomalies in group A could mainly be due to maldevelopment of the facial nerve during an earlier embryonal period while that of group B could have developed after the ninth week of the fetal period and are mostly localized along the second branchial arch.

Enlargement of the vestibular aqueduct

Enlarged vestibular aqueduct, a recently identified anomaly, is typified by an enlarged vestibule, dilation of the ampullated portions of the horizontal and superior semicircular canals, an abnormal cochlea, and hearing loss. In the case described a 16-year-old boy had congenital hearing loss, episodic vertigo, and abnormal vestibular function testing. Tomograms and CT scans confirmed the diagnosis of bilaterally enlarged vestibular aqueducts. The vertiginous episodes decreased in frequency and severity with a no-salt-added diet. The authors conclude that the enlarged vestibular aqueduct is associated not only with other structural inner ear abnormalities and hearing loss, but also with abnormal vestibular function.

Four variations of the Mondini inner ear malformations as seen in microdissections

Four variations and degrees of severity of the Mondini malformation were found in the temporal bones from two neonates, one with congenital heart disease and the other with trisomy D, and from one teenager with leukemia: 1) short cochlea and normal vestibular organs; 2) short cochlea and persistent horizontal canal anlage; 3) markedly shortened cochlea with no modiolus, wide internal auditory meatus, and persistent horizontal canal anlage; 4) same as variation 3, but with persistent anlagen in all semicircular canals. Variations 3 and 4 were from the case of trisomy D, in which the left cochlea had a normal hair cell population but few nerve fibers, and the intraganglionic spiral bundle was displaced from Rosenthal's canal to the osseous spiral lamina. The right ear had no cochlear nerve fibers; the organ of Corti was present, but hair cells were unusually small. In the case of trisomy D, both ears showed subtotal loss of vestibular nerve fibers. Although the rudimentary cristae of the right ear had numerous hair cells, the macular hair cells were fewer and malformed. No hydrops was present.

Congenital anomalies of the inner ear

This study investigated congenital anomalies occurring in the inner ear, with particular attention to their features, localizations, and frequencies. Seventy-seven human temporal bones obtained from 53 individuals, aged one day to 39 years, each of whom had anomalies of the external ear, middle ear, and/or inner ear, were used for this study. The temporal bones had been removed at autopsy, fixed, dehydrated, embedded in celloidin, and sectioned horizontally or vertically at 20 microns. Every tenth horizontal section or every 20th vertical section was stained with hematoxylin and eosin, mounted, and studied under a light microscope. There were 206 inner ear anomalies (117 in the vestibular system, 79 in the cochlea, 10 in the internal auditory meatus) in the 51 bones studied. Fifty-four different features of anomalies were present at 33 different locations in the inner ear. The most frequent anomalies observed were shortened cochlea (23 bones), enlarged vestibule (17 bones), wide cochlear aqueduct (16 bones), absence of lateral semicircular canal (14 bones), and large osseous lateral semicircular canal (10 bones). The most common site of inner ear anomalies was thus the lateral semicircular canal, which was involved in 46 of the 206 anomalies observed; the anomalies in this organ were variable in type. The implications of inner ear anomalies are discussed as they relate to fetal development, inner ear dysfunction, and clinical interpretation of polytomographic studies.

"Spinner" cephalopods: defects of statocyst suprastructures in an invertebrate analogue of the vestibular apparatus

Individuals of seven species of coleoid cephalopods (three species of octopus, three of squid, and one of cuttlefish), that were cultured and reared in laboratory aquarium systems, had a behavioral defect at hatching which was characterized by an inability to control orientation while swimming. These defective animals were designated as "spinners." An examination of statocysts from individuals of five of the affected species revealed abnormalities of the neuro-epithelial suprastructures: absence or malformation of the statolith of the gravity receptor system and absence of the cupulae of the angular acceleration receptor systems. The sensory epithelia did not differ from those of normal animals, nor did the synaptic structures and relationships, when examined both with scanning and transmission electron microscopy. The abnormalities were compared with congenital defects of the neuropeithelial suprastructures of the vestibular apparatus (especially in mammals). The defects observed in statocysts of spinner animals are thought to be the result of environmental causes, such as the temperature or chemistry of the seawater in the transportation vessels or rearing systems, rather than genetic causes.

Malformations of vestibular organs following low dose gamma irradiation during embryonic development

Pregnant mice were whole-body irradiated on the 12th, 13th and 16th gestational day with single doses of 0.5, 1, 2, 3, 4, 10 and 20 Gy, using a 60Co source. No surviving litters occurred in groups exposed to more than 2 Gy. Below this dose, irradiation can cause malformation of the cristae ampullares and the maculae. Malformations were more severe and more frequent in fetuses exposed on the 12th than on the 13th gestational day, indicating that, prior to or the earlier during morphogenesis irradiation takes place, the more vulnerable is the developing tissue. Inner ears exposed to irradiation on the 16th gestational day did not reveal severe malformations.

Klippel-Feil syndrome and associated ear deformities

The Klippel-Feil syndrome is characterized by a short, thick neck with restricted head mobility and a low occipital hairline. The head appears to rest directly on the thorax and the trapezius muscles flare out on either side of the neck, producing a pterygium-like effect. Cervical roentgenograms demonstrate fusion of some or even all of the vertebral bodies into bony blocks. Ear deformities occur in approximately one-third of the Klippel-Feil patient population. We report five cases of Klippel-Feil syndrome and describe their otologic and roentgenographic features. Although no single characteristic otologic or audiologic problem is identified, a proclivity for major malformations of involved ears is demonstrated. Early audiometric and otologic evaluation is indicated when the diagnosis of Klippel-Feil syndrome is made.

Otological aspects of the earpit-deafness syndrome

The results of a systematic study of the otological aspects in 13 cases of earpit-deafness syndrome are reported. The audiometric, radiological and vestibular findings as well as the results of exploratory tympanotomies with and without stapedectomies are discussed together with the results reported in the literature. A convincing explanation of the poor results of exploratory tympanotomies in cases with mixed hearing loss is not furnished. If the hearing loss is confined to conduction and ankylosis of the stapes or a disconnection of the ossicular chain is suspected, exploratory tympanotomy can be expected to be successful.

A syndrome with mixed deafness, Mozart ear, middle and inner ear dysplasias

A 10-year-old boy presenting a disorder of multiple malformations with an otologic component consisting of mixed deafness, Mozart ear, thin stapes, small oval window and agenesis of the semicircular canals, was studied. A comparative analysis of similar malformation-entities has permitted the delineation of a previously undescribed syndrome.

Temporal bone histopathologic findings in congenital anomalies of the oval window

The histopathologic findings in five temporal bones from three cases showing various stages of oval window development arrest are presented. The anomalies ranged from complete absence of the oval window to congenital cartilaginous fixation of the stapedial footplate. Surgical approaches fro establishment of a new oval window must take into consideration the frequent association of facial nerve anomalies with anomalies of the oval window.

Vestibular fenestration and stapedioplasty in congenital stapes and vestibular window abnormality

In this paper the results of vestibular fenestration and stapedioplasty in cases of congenital stapes deformity and vestibular window abnormality are presented. The problems in the surgical reconstruction of the middle ear transmission system, especially the importance of the areal ratio between the tympanic membrane and the vestibular window and the ossicular lever action, are discussed. The following conclusions were reached: 1. The area of the new vestibular window should be greater than 2.0 x 1.0 mm, i.e., one third of normal. 2. Hearing gain was about 1.5 times better after incus-stapedioplasty than after malleus-stapedioplasty. It is recommended that an effort be made to adopt incus stapedioplasty whenever possible.

The large vestibular aqueduct syndrome

The radiographic observation of 50 patients, each having an enlarged (greater than 1.5 mm. diameter) vestibular aqueduct, are analyzed. In addition to the aqueduct other associated inner ear anomalies have been identified in 60% of this population including: enlarged vestibule (14); enlarged vestibule and lateral semicircular canal (7); enlarged vestibule and hypoplastic cochlea (4); and hypoplastic cochlea (4). The large equeduct then presumably represents an arrested phase of inner ear development common to all 50 cases. Only 8 of these cases may fall into the Mondini or Mondini-Alexander classification wherein cochlear abnormalities have been identified. The size of the aqueduct ranged from 1.5 to 8 mm. in the anteroposterior diameter; the clinical incidence is 50 in 3700 consecutive cases referred for inner ear tomography. Bilateral involvement is twice as common as unilateral with a female to male predominance of 3:2. Most cases are associated with congenital hearing losses.

The temporal bone in the preauricular pit, cervical fistula, hearing loss syndrome

Histological study of the temporal bones of an infant with the preauricular pit, cervical fistula, hearing loss syndrome revealed abnormalities in the middle ear, the vestibular system, and the cochlea. There is a gross bilateral abnormality in the form and relationship of the middle ear spaces, the middle cranial fossa and the inner ear. The horizontal canal lacks ampulla and crista; the posterior canal terminates a short distance from the ampulla. The cochlear cavity is approximately four fifths of normal size. The modiolus of the cochlea shows minor abnormalities. Spiral ganglion cells and peripheral nerve fibers are present in all coils, but are below normal in population in the basal and apical coils. The stria vascularis is slightly deformed and partly atrophic in the upper apical coil. An occasional concretion is present in the base of the stria vascularis in the middle and apical coils.

Hearing in patients with congenital deformity of the inner ear

Congenital abnormalities of the bony labyrinth and internal auditory meatus range from complete absence to minor anomalies compatible with normal cochlea function. A 'follow-up' survey to assess the hearing of 56 patients with abnormalities of the inner ear shown by tomography was made. The hearing levels are discussed in relation to the tomographic appearances and comparison made with other series of inner ear abnormalities demonstrated both radiographically and histologically.

The Syndrome of Enlarged Vestibule and Dysplasia of the Lateral Semicircular Canal in Congenital Deafness

A 5-year-old deaf-mute girl was shown on petrous bone tomography to have bilateral enlarged vestibules with assimilation of the lateral semicircular cannals, bilateral absence of the cochlea, aplasia of the left internal auditory canal with only the facial nerve compartment being present, and hypoplasia of the right internal auditory canal. The embryological basis of these inner ear abnormalities is discussed.

Osteogenesis imperfecta congenita and tarda: a temporal bone report

The temporal bone report of an operated case of osteogenesis imperfecta tarda is presented. Histological examination confirmed the presence of bilateral fixation of the footplate by otosclerosis as the cause of the conductive hearing loss. Fragility of bony septae in the mastoid and of the stapedial crura were observed. Sensorineural impairment in later years with a reduction in neural elements in the cochlea appear related to the extent and activity of the otosclerotic foci. Additional temporal bone reports of three cases of osteogenesis imperfecta congenita show lack of deposition of the skein-like bone in the endochondral layer, sparse bony septae in marrow spaces and deficiency of the perosteal layer. The stapedial crura were thin and in two cases both were deformed and fractured.