Tetsuya Egami

Inner ear Hemorrhage and Endolymphatic Hydrops in a Leukemic Patient with Sudden Hearing Loss

Several significant histopathological findings were noted in a case of sudden hearing loss in a patient with chronic lymphocytic leukemia. The major pathological findings were leukemic hemorrhage into both perilymphatic and endolymphatic spaces in the cochlear and vestibular systems, endolymphatic hydrops in the cochlea and sacculus, and a relatively narrowed and straightened vestibular aqueduct and endolymphatic sac. Additional interesting findings include: loss of hair cells in the organ of Corti and vestibular end-organs; destruction of the stria vascularis (possibly the origin of the blood); fibrosis in the perilymphatic spaces in the cochlea and the vestibule, and in the endolymphatic space in the vestibule; and new bone formation in the perilymphatic spaces in the vestibule. The leukemic infiltrate observed in both the cochlea and the vestibule was not considered to be significant. Hemorrhage into the cochlea is thought to be the most reasonable cause of the sudden hearing loss in this case. Also discussed are fibrosis and osteogenesis as a late consequence of hemorrhage, and the coexistence of endolymphatic hydrops with an anomaly of the vestibular aqueduct and endolymphatic sac.

Hypoplasia of the Vestibular Aqueduct and Endolymphatic SAC in Endolymphatic Hydrops

Four temporal bones from three previously reported cases showing endolymphatic hydrops and pathology of the vestibular aqueduct (VA) and endolymphatic sac (ES) were investigated further. Pathology of the VA and ES was studied by measuring the sizes of the VA and ES, paying particular attention to the proximal rugose portions. A medial-view graphic reconstruction was created to delineate the course and size of the VA, as well as its correlation with neighboring structures (posterior canal and cochlea). In addition, 20 control temporal bones were selected and measured for quantitative study of the sizes of the VA and ES. The four pathologic temporal bones were shown to have small, simple, tube-like VA and ES, without surrounding bony pathology. This appeared to be congenital hypoplasia characterized by hypoplastic funnel-shaped dilatation of the VA and hypoplastic rugose portion of the ES. Anterior dislocation of the distal portion of the VA and poorly developed periaqueductal air cells were also noted in the pathologic bones. Susceptibility to endolymphatic hydrops, difficulty in radiologic visualization of the VA, and surgical exposure of the ES are discussed in relation to hypoplasia of the VA and ES.

Course and Contents of the Paravestibular Canaliculus

The purpose of this study is to describe the anatomy of the paravestibular canaliculus (PVC) in detail, specially its course in relation to the vestibular aqueduct (VA) and its vascular contents. Serial horizontal sections of 20 normal human temporal bones were stained either with hematoxylin and eosin, by Verhoeff-van Giesons method, or by Mallorys method, and studied under the light microscope. Graphic reconstruction of the VA and the PVC was performed in some of the cases. In this study, the following new anatomical information on the common course and vascular contents of the PVC was obtained: 1) two PVC are present in the area near the vestibular orifice of the VA; 2) the PVC merges with the VA in the area near its cranial orifice without any particular branching, and does not enter the posterior cranial fossa; 3) veins course through the entire length of the PVC whereas arteries course only through the posterior cranial fossa side of the PVC. It appears that veins are the major contents of the PVC and that these veins represent the main venous drainage system from the vestibule. It also appears that arteries in the PVC supply the blood from the posterior cranial fossa mainly to the PVC itself.

Temporal bone anomalies associated with congenital heart disease.

A temporal bone histopathological study was conducted to detect temporal bone anomalies in 20 ears (10 cases) of individuals with congenital heart anomalies. We restricted our study to patients more than one year of age, and to heart anomalies of unknown etiology. The temporal bones were obtained from refrigerated cadavers, fixed in formalin, embedded in celloidin, cut in a horizontal plane, stained with H & E, and mounted on glass slides for light microscopic study. Anomalies observed in the middle ear were: remnants of mesenchymal tissue (8 ears), wide angle of the facial genu (6 ears), persistence of the stapedial artery (5 ears), large defect of the facial canal (4 ears), high jugular bulb (4 ears), and bulky incus (2 ears). Inner ear anomalies consisted of a shortened cochlea (5 ears), anomaly of the horizontal canal (3 ears), anomaly of the posterior canal (2 ears), obliteration of the cochlear aqueduct (2 ears), and patent utriculoendolymphatic valve (1 ear). Most of the anomalies observed appeared to be due to arrested development, and resembled features which may be found at various stages of fetal life. Structural anomalies were more commonly found in the mesoderm than in the ectoderm, and middle ear anomalies were more frequently encountered than anomalies of the inner ear. No definite relationship between these anomalies observed in the temporal bone and hearing problems which had been recorded clinically for these patients could be detected. However, the large defect (more than one third of the circumference) of the facial canal, the high jugular bulb, and the stapedial artery persistence should be recognized as problems since they may be encountered during middle ear surgery.

Experimental Study of Nystagmus Induced by Injecting Various Solutions into the Middle Ear Cavity

Injecting of various solutions into the middle ear cavity of cats and rabbits provoked certain characteristic types of nystagmus which resembled caloric nystagmus or clinical cases of peripheral vestibular disorders. Solutions with different degrees of specific gravity, osmotic effect and ion composition were used in this study. Direction-changing positional nystagmus, irritative nystagmus, and paralytic nystagmus were elicited according to the physical or chemical properties of each solution. Histological findings showed mild changes in the perilymphatic space and/or in the endolymphatic space in the period with some characteristic types of nystagmus. Infiltration of the substances into the inner ear fluids from the middle ear cavity via a round window membrane were probably responsible for these types of nystagmus.

Noise-induced hearing loss. A human temporal bone case report.

The histopathology of a case of profound hearing loss which seemed to be induced by noise exposure (explosions and drillings in a gold mine) is reported. The patients only residual hearing was 250 Hz at 90 dB SPL in the right ear. The major histopathological findings were as follows: Bilateral absence or collapse of Cortis organ was observed in the middle and basal turns of the cochlea; however, in the remaining area (approximately 6.0 mm in range in the apical portion of the cochlea) Cortis organ was well-preserved with a moderate loss in number or atrophy of the hair cells. Bilateral marked decrease of the cochlear nerve was noted in the middle and basal turns; however, the nerve was well-preserved in the remaining apical portion (approximately 6.0 mm in range) of the cochlea. These pathological findings were somewhat less severe in the right cochlea than in the left. In general, there was good correlation between the profound hearing loss and the extensive pathological findings in Cortis organ. The residual hearing in the right ear would seem to be explained by the less severe pathological changes found in the apical portion of the right cochlea than in the left cochlea. In addition to noise exposure, other possible etiological factors contributing to this hearing loss are discussed. These include diabetes mellitus and presbycusis.

Experimental Direction-Changing Positional Nystagmus induced by Intra-Tympanic Infusion of the Drugs

比重の異なる薬剤を1側の中耳腔に注入する事によって, 比重の違いに応じた, 内耳性の方向交代性 (上向性及び下向性) 頭位眼振のモデルを作成する事ができた. エチルアルコールでは左右側位で方向交代性下向性, Nose up で非注入側向き, Nose down で注入側向きの頭位眼振が出現した. 重水では左右側位で方向交代性上向性, Nose up で注入側向き, Nose down で非注入側向きの頭位眼振が出現した. またアルコールを中耳腔に注入した兎側頭骨標本において, 外側半規管膨大部周辺に染色性の異なる遊出物を認めた.

Positional Nystagmus Induced by Infusion of Saturated NaCl Solution into the Tympanic Cavity

Trans-tympanic infusion of saturated sodium chroride solution into the tympanic cavity was performed in eleven rabbits. Nystagmus was induced in 8 rabbits. The time course of the nystagmus was as follows: spontaneous nystagmus to the injected side, positional and positioning nystagmuses changing to different directions by alternation of the head position were initiated 15-30 minutes after infusion. Spontaneous nystagmus subsided within an hour, although, positional and positioning nystagmuses persisted more than 3 hours. The direction of positional and positioning nystagmuses was to the left when the head was held with the right side down, to the right with the left side down, to the injected side with the nose-up position, and to the non-injected side with the nose-down position, respectively. These nystagmuses disappeared in 24 hours after infusion and caloric response was preserved. Only one rabbit showed persistence of the positional nystagmus to the right when the head was held with the right side down, and to the left with the left side down. Several variable nystagmuses such as pure vertical nystagmus, equivalent to rotatory nystagmus in humans, or rotatory vertical nystagmus presumably originating in the vertical canals were observed in some rabbits. A temporal bone pathology study revealed mild endolymphatic hydrops in the cochlea and saccule, deformed and dissolved cupula in the vertical canals. In addition, basophilic reticulated materials in the endolymphatic and perilymphatic spaces, and homogenous basophilic materials around the maculae and cristae were observed in a case with persistent positional nystagmus.

Anisocoria in Inner Ear Lesions

In experiments using rabbits, the pupil on the side of irritative inner ear lesion showed dilatation, and that on the side of paretic lesion showed constriction. In the clinical observation of patients with unilateral inner ear diseases (134 cases), anisocoria was recognized in 54.5%. In 68.5% of these, anisocoria was induced after applying a drop of neosynephrine. The size of the pupil on the healthy side was smaller in 65.8% than the pupil on the healthy side. Anisocoria in inner ear lesions is believed to be due to vestibulo-sympathetic imbalance through the superior cervical sympathetic ganglion.