Two-nation-wide surveys of Meniere's disease have been carried out by the Vestibular Disorders Reserch Committee of Japan, supported by the Ministry of Health and Welfare of Japan. First survey has already been reported. In the second survey 1564 cases of definite and 1439 cases of presumed Meniere's disease were collected and their epidemiological and clinical features were analyzed. The second survey included the name, sex, age and other necessary items. Some items were compared with the results of the epidemiological and clinical surveys of the Meniere's Disease Reserch Committee of Japan reported in 1971.
A case-control study of Meniere's disease revealed the following triggers or etiological factors: (1) Mental/physical exhaustion, emotional irritability, insufficient sleep, fluctuation in atmospheric pressure and certain foods which were probable triggers of attacks of vertigo. (2) The odd ratios (similarity of relative risk in comparison with controls) of these triggers were 1.7-3.5 times higher in males than in females for emotional irritability and some foods which were higher in females. (3) Mental/physical exhaustion and emotional irritability had the highest odd ratio in the sixth decade. Insufficient sleep had the highest in those under 50 years of age, and fluctuation in atmospheric pressure in those over 60. (4) Smoking, drinking, proximity to cats and hypotension were likely to be triggers of attacks of vertigo.
A study was performed to clarify the clinical characteristics of tinnitus associated with Meniere's disease, as influenced by such factors as unilaterality or bilaterality, glycerol test and ECoG results, types of onset, and time since last attack of vertigo. The criteria used were tinnitus test results and tinnitus scores based on loudness, discomfort level, and interference with life activities. Of the 92 patients studied, 53 (58%) had noise tinnitus and 39 (42%) had tonal tinnitus. The frequencies of tinnitus ranged from low (around 250 Hz) to high. Higher tinnitus scores were observed in Meniere's disease of cochlear or cochlear-vestibular onset, and in patients with bilateral fluctuant hearing loss and positive glycerol tests. Great care must be taken in the treatment of these patients. Noise tinnitus was more apt to occur sooner after the last attack of vertigo than tonal tinnitus, but tinnitus scores were higher when the last attack of vertigo was more than 1 year earlier. This may be due to a decreased psychological tolerance for tinnitus as the vertigo-free period lengthens.
A case of fluctuating hearing loss related to contralateral delayed endolymphatic hydrops (DEH) was first described Schuknecht in 1978. Our patient was a 63-year-old male with diabetes mellitus who developed fluctuating hearing loss and was found to have contralateral DEH. He had had severe hearing loss in the left ear following otitis media when he was six years old. Since the age of 53, he had occasionally noticed fluctuating hearing loss in the right ear along with episodic vertigo of Meniere's type. After admission to our hospital, the audiograms of his right ear revealed periodically-fluctuating hearing loss without vertigo. His hearing in the right ear fluctuated diurnally ; his hearing depression was severe in the morning, improved at noon and became severe again in the evening. Because he had diabetes mellitus, his blood glucose levels were serially determined. It was interesting that the fluctuations of his blood glucose levels preceded those of his hearing in the right ear by approximately three hours.
Questionnaires were sent to homes for the elderly in Shimane prefecture, inquiring about the incidence of vertigo, its characteristics, duration and associated symptoms. Otological examination of 20 patients revealed probable Meniere's disease in 10. The medulla oblongata and temporal bones of 6 SHR rats with a kind of "vertigo" were examined. These SHR rats tilted their heads to one side, and when held, they circled around their tails. Their systolic blood pressures were 200-300 mmHg. In two rats, degenerating neurons which stained deeply with Luxol-Fast blue were observed in the reticular formation of the medulla oblongata. In the temporal bones of all 6 rats, the cochlear structures of the affected side were destroyed and replaced by fibrotic cells. Further study is needed to evaluate these pathological findings.
The three-dimensional imaging used so far has processed digitalized information on the morphology of organs by the computer graphics technique. However, the conventional method has not been used clinically, because the processing of information has been inadequate. We observed the external aperture of the vestibular aqueduct in vivo using three-dimensional imaging by the surface reconstruction method. The width was measured in normal and diseased ears. Significant narrowing was observed in patients with Meniere's disease, while no difference in width was noted between normal subjects and those with chronic otitis media. This technique can be used to examine not only on the vestibular aqueduct but also other structures in the temporal bone. It should be useful in clarifying the pathophysiology of inner ear diseases and also in the surgical treatment.
Complement is known to be involved in many inflammatory reactions. C4a, C3a and C5a, known as anaphylatoxins, cause especially strong inflammatory reaction. Anaphylatoxins injected into guinea pig carotid arteries cause extreme atrophy of the stria vascularis in the cochlea except in the basal turn ; some cochlear nerves show degeneration, and some cochlea show endolymphatic hydrops. These results have been noted in previous reports. In this study, anaphylatoxins made from guinea pig serum treated with zymosan were injected into the tympanic cavities of 15 male Hartley guinea pigs, weighing about 350 g, all susceptible to preyer's reflex. The temporal bones were fixed in 10% buffered formalin, embedded in celloidin, cut into 13 μ sections and stained with hematoxylin and eosin. Pathological changes in the inner ears were observed by light microscopy and all the macrophages in the endolymphatic sac were counted. Reissner's membrans were collapsed in some animals (60%). The stria vascularis in the various cochlear turns were extremely atrophied (40%) and some cochlear nerves showed degeneration. There were more macrophages in the endolymphatic sac than in the controls. These pathological changes were similar to those observed in inner ear diseases in humans. These results suggest that anaphylatoxins in the middle ear can affect the cochlea.
The influence of noise exposure on experimental bydrops in guinea pigs was studied morphologically with light and electron microscopy. Blood sludging and vasoconstriction were observed in the upper coild arterioles and capillaries of the stria vascularis in the 3rd and 4th turns of the cochlea, where outer hair cell loss was also noted. These results suggest that circulatory disturbances following vasoconstriction are caused by noise exporsure, and eventually outer hair cells are damaged.
Soybean agglutinin (SBA), helix pomatia agglutinin (HPA), ricinus communis agglutinin-11 (RCA-II), limax flavus agglutinin (LFA) and wheat germ agglutinin (WGA) were employed to localize, with a lectin-gold technique, specific carbohydrates on thin sections of guinea pig stria vascularis embedded in Lowicryl K4M. Galactose and N-acetylgalactosamine labeled with SBA, HPA and RCA-II were found in many cyto-plasmic vesicles and endosomes located in the supra-nuclear region, as well as in the microvilli and in the plasma membranes of internalization of marginal cells. LFA labeling, indicating the distribution of sialic acid residues, was found in the basement membrane of the perivascular spaces and intercellular spaces between marginal and intermediate cells and between marginal and basal cells. Plasma membrances, how-ever, were unlabeled in all types of cells. WGA binding sites showing the localization of N-acetylgalactosamine, on the other hand, were detected along the plasma membranes of all types of cells constituting the stria vascularis and in some supranu-clear cytoplasmic vesicles in marginal cells. These findings revealed that the membranes of internalization and some cytoplasmic vesicles were as-sociated with endosomes in the supranuclear region of the marginal cells. It is probable that these struc-tures are related to the functions of absorption and secretion, and that the carbohydrates labeled with SBA, HPA and RCA-11 are recirculated in this system, the exchange between Na+ and K+ facilitating.
Inner car hair cells of the guinea pig were isolated mechanically and enzymatically, and their motility and the presence of F-actin in the cytoplasm were investigated. 1. Inner hair cells and vestibular hair cells tended to lose their cell body shape during the isolating procedure more than did outer hair cells. 2. In outer hair cells F-actin was demonstrated as the infracuticular network (ICN), indicating that ICN is one expression of the presence of F-actin. 3. Further studies by other methods are needed to determine whether inner hair cells have F-actin in their cytoplasm. 4. The existence of ICN in the vestibular hair cells shows that F-actin is present in the cytoplasm and suggests that they have motility.
Cochlear circulation was measured in guinea pigs by three methods : laser Doppler, hydrogen clearance and oxygen tension (PO2). The effect of blood pressure (BP) changes was examined with a doppler needle probe plased on the 2nd turn, and a hydrogen or oxygen-sensitive microelectrodes inserted into the endolymph of the same turn. The BP was elevated by an intravenous infusion of norepinephrine and lowered by bleeding. The cochlear blood flow (PO2) correlated well with the BP. However, the percentage of change of cochlear blood flow (PO2) at low BP was less than that at a high BP, indicating that cochlear vessels have an autoregulating ability at a low BP.
This study was designed to evaluate the effects of various agents (2.4 ml/kg 50% glycerol, 1.6 ml/kg 70 % isosorbide, 5.0 ml/kg 20 % mannitol, 5.0 ml/kg 7% 061 Meylon, 10 ml/kg 1% Cephadol) on the cochlear blood flow of guinea pigs with experimentally induced endolymphatic hydrops. The various agents were administered intravenously to the hydropic animals and to normal controls, and the cochlear blood flow was measured by a laser Doppler flowmeter. Blood flow increases lasting several minutes were seen with all agents except Cephadol in both normal and hydropic animals. The greatest increases occurred with glycerol, followed in order by Meylon, isosorbide, and mannitol. Decreases in cochlear blood flow were seen following Cephadol administration. No differences were observed in the reaction patterns to the various agents between the normal and hydropic groups, but the degree of reaction to each agent was slightly higher in the hydropic animals than in the normals.
Endolymphatic hydrops was induced in albino guinea pigs by obliteration of the endolymphatic sac and duct. High doses of furosemide (FUR) (50 or 80 mg/kg) were injected intravenously in the 3rd, 6th, 12th or 24th postoperative week and the effect on the cochlear endolymphatic potential (CEP) was examined in order to assess the functional capacity of the electrogenic pump in the stria vascularis. Low doses of FUR (5 or 10 mg/kg), which did not influence the CEP in normal or hydropic ears, were administered in the same way, and the input-output functions of the Ni induced by a click were monitored. The CEP was lower in the animals with endolymphaxic hydrops than in the normal controls and then tended to decrease gradually. When 50 mg/kg of FUR was given, the hydropic ears showed a greater depression of the CEP than the normal ears, indicating increased susceptibility to FUR in hydropic ears. Eighty mg/kg of FUR, which was enough to abolish almost all of the positive component of the CEP, reduced the CEP to -40 mV 12 weeks after surgery. This finding suggests that the negative K+ diffusion potential is normally maintained for at least 12 weeks postoperatively. The maximum recovery rate of the CEP after FUR injection (80 mg/kg) was significantly slower in the 24-week animals than in the other group, indicating more severe dysfunction of the strial electrogenic pump. In terms of the in-put-output functions of the Ni, no shift of the curves was observed up to 120 minutes after the administration of low doses of FUR in either the hydropic or the normal ears. It was concluded that the diuretic effect of FUR, could not improve the hearing of ears with endolymphatic hydrops.
Head-shaking nystagmus and trapezoid rotation tests were performed on the same day in patients with unilateral peripheral disorders, and the results of the two tests were compared. An analysis of 84 data from 37 patients proved that the head-shaking nystagmus test gave almost the same results as the trapezoid rotation test. However, head-shaking nystagmus must be tested carefully, because the angular acceleration induced by head-shaking far exceeds the physiologic threshold of the semicircular cannals, and cervical factors during head-shaking may influence the test results. Therefore, discrepancies between the two tests were often observed in this survey.
Pendular rotation in the eccentric position produces the same angular stimulation as conventional pendular rotation (i. e., centric rotation) ; moreover, it involves linear centrifugal and tangential acceleration forces which act on the otolith organs. In the eccentric position, normal subjects showed a greater gain of slow phase eye movements at 0.64 Hz, than when the head was in the centric position. We conclude that it is possible to diagnose otolith dysfunction by these comparison. In this study, we applied centric and eccentric pendular rotation tests to eleven patients with Meniere's disease and seven patients with vestibular Meniere's disease to investigate their otolith function. With in one month after their first attack or after a recent attack, no gain enhancement with eccentric rotation was noted in either group. Others showed normal gain enhancement in the eccentric rotation test. We conclude that there is no difference in otolith function in patients with Meniere's disease and those with vestibular Meniere's disease.
Electrocochleography (ECochG) was used to test 137 ears of patients with definite Meniere's disease, 29 normal ears and 383 ears with other types of sensorineural hearing loss. One of the questions raised in clinical ECochG is whether to use a clik or a toneburst to diagnose endolymphatic hydrops using SP/ AP. First, it was shown that SP/AP was much more useful than SP amplitude in the diagnosis of Meniere's disease. All investigators employing both the extra-and transtympanic approaches, except two study groups, used a click for detecting endolymphatic hydrops. There was no significant difference in SP/AP between click and tone-burst use in any disease in our clinic. Many investigators have proposed a normal upper limit of SP/AP with a mean+2 SD, a 99 % confidence limit or a mean+3 SD, and have used those limits to diagnose endolymphatic hydrops. Those limits vary from 0.30 to 0.51. The mean values proposed by all study groups show little difference, being close to 0.25, in spite of differences in intensities and intervals of stimulus and high cut and low cut filters in the preamplifier. Any differences depend on the statistical decision of the limit and the size of standard deviation. It was concluded that both stimuli could be used in clinical ECochG and 0.30 to 0.40 of SP/AP would be adequate as the normal upper limit. The statistical normal range was determined at a mean+2 SD or 99% confidence limit.
The lowering of skin temperature by caloric stimulation was markedly inhibited by the transdermal application of TTS-scopolamine, but metopic cooling was not affected. Intense vestibular inputs project to the 2V area through the vestibular nuclei and reticular formation, causing the sensation of vertigo, and lowering the cutaneous temperature simultaneously via the sympathetic system, and also the unpleasant symptoms of nausea and/or vomiting through the vomiting center. The present findings reveal that TTS-scopolamine dose not affect the somatic autonomic reflex system but markedly inhibits the vestibular response, suggesting that the effect of this drug may be due to inhibition of the neuron network containing the vestibular nuclei and the reticular formation.
We measured the skin temperature of the cheeks of patients with Meniere's disease by thermography before and after frontal cooling by ice. Before cooling it did not differ from that of healthy controls, but cooling caused significant asymmetry in the patients. Moreover, in patients with Meniere's disease, the asymmetry of cheek skin temperature after frontal cooling was greater during activity than at rest. Skin temperature is controlled mainly by the sympathetic nervous system. Therefore, these findings suggest that asymmetry of sympathetic nerve function is a possible cause of attacks of Meniere's disease.
Autoimmune inner ear lesions were induced in SD rats by immunizing them with native type II collagen. All immunized animals had high levels of antibodies to native type II collagen. The histopathological changes observed in the inner ear of immunized animals included mild extension of Reissner's membrane (22%), atrophied organ of Corti (22%) and spiral ganglion cell degeneration (35%). These findings suggest that immune responces directed against type II collagen can induce inner ear disorders.
Studies on disequilibrium have been conducted with gait analysis of patients with Meniere's disease in a basic program of gait training. Using the same apparatus and program of analysis, we measured the duration of the stance phase, the swing phase and the double support phase of the gait cycle to determine the differences between the right and left legs and the changes in the gait cycle at various walking speeds. We tested 25 patients with a definitive diagnosis of Meniere's disease in a quiescent phase and 15 healthy adults. All the subjects were instructed to walk at ordinary, faster-than-ordinary and slower-than-ordinary speeds. The Meniere's disease patients were divided into three groups : group O without nystagmus, group R with rightward positional nystagmus and group L with leftward positional nystagmus. No significant difference in the unit pace duration of stance and swing phases of either right and left leg was noted between the O, R, L and healthy groups. Nor was there any significant difference when the pace was varied. There was a significant difference, however, in the duration of the double support phase consistent with the direction of nystagmus (vestibular asymmetry), that is, a "phase shift", in patients with nystagmus alone when they walked at ordinary and faster-than-ordinary speeds. This phase shift can be considered to be a measure of a latent abnormal gait pattern.
A training-rehabilitating system for patients with disequilibrium was worked out, and patients with vestibular disorders were trained with this system. Training methods : A) Before training, the patients were examined for impairment, disability and handi-cap. Activities of daily living as a parameter of disability were investigated with a questionnaire. The following 10 movements were examined as the equilibrium function test, and those which they had diffi-culty in performing were individually determined : (1) eye movements, (2) head movements, (3) eye-head coordination, (4) body movements, (5) standing, (6) stepping, (7) walking, (8) revolving without any support, (9) walking around a circle, and (10) going up and down stairs or a slope. B) The patients received training to improve the defective movements determined in A). C) The effects of the training were evaluated by stabilometry and the gait test (10m). Results : Case 1, a 59-year-old female with bilateral vestibular dysfunction complained of dizziness when standing up, disequilibrium while walking and equilibrium disturbance while turning to the right or left. Training comprised standing, stepping, and walking was given. After 3 months of training, her equilibrium and the results of stabilometry and gait tests were improved. Case 2, a 55-year-old female had sudden deafness of the right ear and vertigo. Six months after training, she regained equilibrium function. Case 3, a 76-year-old female with bilateral vestibular dysfunctions. When training was discontinued, her disequilibrium worsened. Three months after the resumption of training, the results of stabilometry tests were improved.