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Since the publication of the article entitled "Placebo effect in surgery for Meniere's disease. A double-blind, placebo-controlled study on endolymphatic sac shunt surgery" by Thomsen et al. in 1981, endolymphatic sac surgery for Meniere's disease has tended to receive a lower evaluation. Investigators who read only its abstract were likely to understand that this study was well planned and performed under a doubleblind, placebo-controlled study and that the conclusion would be reliable. The results showed that only a minor difference (p

We reported a patient with cavernous hemangioma of the internal auditory canal. A 47-year-old man demonstrated progressive hearing loss and facial palsy on the left hand side over 4 years. A small tumor was detected in his left internal auditory canal by magnetic resonance imaging (MRI). The lesion displayed iso-signal intensity in T1-weighted images, high signal intensity in T2-weight images, and positive Gadolinium enhancement. Under tentative diagnosis as neurinoma, the tumor was totally removed by the translabyrinthine approach. The red tumor had compressed the facial and cochlear nerves, and adhered to the vestibular nerve in the internal auditory canal. It was diagnosed as cavernous hemangioma by immunohistochemical examination. There has not been any sign of recurrent tumors, but hearing loss and left facial palsy persisted after surgery. A cavernous hemangioma of the internal auditory canal tends to manifest with progressive hearing loss and facial palsy based on a review of past reports.

The atrial natriuretic peptide family (ANP family) is comprised of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP). These peptides regulate body fluid and blood pressure homeostasis as a neuropeptide in the central nervous system as well as a cardiac hormone in the periphery. To assess the possible physiological role of the ANP family, we investigated the immunohistochemical localization of these peptides in the rat inner ear. ANP-like and CNP-like immunoreactivities were observed in the spiral ligament just beneath the stria vascularis, spiral limbus, dark cell area, endolymphatic sac, spiral ganglion cells and vestibular ganglion cells. We could not detect specific BNP-like immunoreactivity in the inner ear. These observations were consistent with our previous study concerning the ANP family gene expression. The results suggest that the ANP family influences the metabolism of the inner ear fluid as well as afferent nerve activities in the inner ear.

Based on the data obtained from two Japan-wide surveys of Meniere's disease (MD) conducted by the Meniere's Disease Research Committee of Japan (1975-76) and the Vestibular Disorders Research Committee of Japan (1982-84), the epidemiological characteristics of unilateral severe MD were evaluated among 810 patients with definite MD. Of these 230 had severe MD, 48 of them had with profound hearing loss (UPHL group) with a pure tone average of the affected ear at 500, 1000 and 2000Hz of 70dB or worse, and 182 had markedly disabling attacks of paroxysmal vertigo for more than 3 years (UDV group).1) The sex ratio in the UPHL group was 1 : 1, but there were more females than males in the UDV group.2) Age at onset of MD peaked in the third decade in the UPHL group, and in the fourth decade in the UDV group.3) In the past history, otitis media was significantly more common in both the UPHL and UDA group than in non-severe patients.4) Insomnia was more likely to cause vertigo attacks in the UPHL group than in non-severe patients.

In order to clarify the characteristics of the severe Meniere's disease we analyzed various epidemiological factors, such as sex ratio, duration of illness, etc., in a series of 958 patients with a definite Meniere's disease. The data were obtained from the three Japan-wide surveys of Meniere's disease conducted by the Meniere's Disease Research Committee of Japan (1975-76) and the Vestibular Disorders Research Committee of Japan (1982-84 & 1990). All subjects were classified into two groups : severe and non-severe. The former contained patients with bilateral and unilateral disease. Those with unilateral severe disease had suffered from markedly disabling attacks of paroxysmal vertigo for more than 3 years.1) There were 95 patients with bilateral disease, 238 with unilateral severe disease and 625 with non-severe vertigo. About 40% of the subjects had severe disease.2) Over half of the patients with definite Meniere's disease were females. (bilateral disease 64% ; unilateral severe disease 52% ; non-severe disease 53%)3) The average duration of illness in the severe group (bilateral, 7.1 years ; unilateral, 8.5 years) was longer than that in the non-severe group (3.3 years).4) The incidence of otitis media in the past history was higher in the unilateral severe group than in non-severe group.5) Changes in the atmospheric pressure and in the emotional state were more likely to trigger vertigo attacks in the severe group than in the non-severe group.

In this study we attempt to determine whether the dominant negative summating potential (DNSP) is present during the earlier stages of induced hydrops development. Electrocohleographs (ECoG) were taken 3 days, 4 days, 1 week, 2 weeks, 3 weeks, and 10-20 weeks after obliteration of the endolymphatic sac in guinea pigs with electrodes in the basal turn scala vestibuli.The action potential (AP) thresholds rose and the AP amplitudes decreased with time following surgery. The increases in the summative potential (SP) amplitudes and in the rises in the SP/AP ratios at 95 dB pe SPL in response to clicks tended to be greater 3 and 4 days postoperatively than subsequently. These results indicate that the potential for DNSP exists during the early stages of endolymphatic hydrops formation, before the hydrops is fully developed.

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.

Schuller projection films and CTs encompassing the lateral semicircular canal were obtained in 22 patients with unilateral Meniere's disease ; similar procedures were performed on 16 patients with unilateral chronic otitis media as controls. The distance between the posterior semicircular canal and the posterior petrous surface (P-P distance) was measured in the CTs, and the distance between the capsula ossea labyrinthi and the sigmoid plate (C-S distance) in the Schuller projections. The statistical differences between the affected ears and the non-affected ears were then calculated in both Meniere's disease and chronic otitis media. The correlation between the P-P distance and the C-S distance was also determined.1) In the affected ears in unilateral Meniere's disease, P-P and C-S distances was significantly shorter than in the non-affected ears. No correlation was found between the P-P distance and the C-S distance.2) The C-S distance was shortest in the affected ears of patients with chronic otitis media. The C-S distance appeared to be influenced by middle ear infection : apparent differences due to the radiological projection angle must be taken into consideration.3) The P-P distance appears to be more useful than the C-S distance for the evaluation of Meniere's disease.

Since the first reports of endolymphatic hydrops in Meniere's disease by Yamakawa and Hallpike & Cairns in 1938, various attempts have been made to induce endolymphatic hydrops experimentally in animals. We reviewed the literature from 1947 to 1990 on methods of inducing experimental endolympphatic hydrops and summarized these methods on the basis of Schuknecht's classification of human endolymphatic hydrops into progressive and non-progressive types. The progressive pattern of hydrops was induced experimentally in guinea pigs using the silver nitrate cauterization method developed in our department in 1981. This type of experimental endolymphatic hydrops has been found particularly suitable as an animal model of Meniere's disease, since endolymphatic hydrops in Meniere's disease is always of the progressive pattern.

The elasticity of Reissner's membrane was investigated in guinea pigs with experimentally induced endolymphatic hydrops. Isosorbide, an osmotic diuretic, was administered to reduce the size of the endolymphatic space and thereby decrease pressure on the bulging Reissner's membrane. If elasticity is present, a consequent shortening of this membrane would be expected. Significant folding in the basal turn of the cochlea was observed, but careful measurement with a microscope, video camera, and computer arrangement revealed no contraction of Reissner's membrane in comparison with guinea pigs which had not received isosorbide. This indicates a lack of elasticity in the membrane following the occurrence of endolymphatic hydrops, suggesting irreversibility of the elongation process.

Endolymph-perilymph shunts were produced in 20 guinea pigs with endolymphatic hydrops induced by the silver nitrate method. The shunt was created between the scala media and the scala tympani through the basilar membrane in the basal turn of the cochlea. At various intervals (3 hours-27 days), animals were sacrificed and prepared for pathological examination. In 10 of the 20 animals the shunt was visible, varying from a small fissure to 200 microns in width. In the other 10 animals the shunt had probably healed over, because fracture lines were often observed. In those examined 3 hours to 3 days after operation, there was slight membranous collapse. After 7 to 27 days however, the animals showed hydrops even if the shunt was still patent. Severe degenerative changes of Corti's organ and severe atrophy of the stria vascularis were observed adjacent to the shunt area. The temporal bone of a patient with otosclerosis and Meniere's disease was also studied. Otosclerosis had invaded the lateral wall of the cochlea inducing atrophy of the spiral ligament, stria vascularis and basilar membrane to create a natural endolymph-perilymph shunt between the scala media and the scala tympani. This structure resembled the shunt produced experimentally in guinea pigs. The patient had suffered from vertigo which later disappeared although hearing loss was severe. The shunt may have worked as a pressure-releasing fistula.

During the endolymphatic sac shunt surgery for 37 cases of Meniere's disease (including 2 cases of syphilitic endolymphatic hydrops), 21 endolymphatic sac specimens were collected for immunohistopathological observation. These specimens were fixed in cold 95% alcohol, emmbeded in paraffin and processed for immunohistopathological study. They were then stained with FITC labeled goat-antihuman IgG, JgM, IgA and gamma globulin. Four specimens out of 21 showed positive finding in the immunofluorecent study and one showed brown pigmentation in the light microscopic study. One of 4 specimens, which displayed positive finding in the immunofluorecent study, showed ring structure of 3 layers. Outer layer was stained with IgM, middle layer with IgG and inner layer with IgA. This structure resembles a occuluded capillary vessel.

The therapeutic effect of gamma globulin was tested on 19 bilateral Meniere's disease patients with profound hearing impairment and fluctuation loss. Patients had not responded to steroid treatment, and showed lower than normal levels of gamma globulin.Treatment proved effective in 13 of the 19 cases, ineffective in 4 cases, and of uncertain effect in 2 cases.The nature of these results suggests that further investigation of this method of therapy would be of value.

Temporal bones of patients with Meniere's disease were examined using roentgenography. Materials were obtained from 54 patients with unilateral meniere's disease and 14 patients with bilateral Meniere's disease.In cases of unilateral Meniere's disease, the pneumatization of temporal bones of the diseased ear was more extensive than that of the healthy ear. In bilateral Meniere's disease, either a sparse or a total lack of the pneumatization in each side was observed in almost all cases. Using Schuller's method, the distance from sigmoid sinus to labyrinth capsule of the temporal bone was measured in all cases. In cases of unilateral Meniere's disease, the distance in the diseased ear was shorter than that in the healthy ear. In bilateral cases distances on both sides were short.Using Stenvers method, the diameter of the internal auditory canal of cases was measured in cases of unilateral Meniere's disease. The diameter of the diseased ear and healthy ear was almost the same in most cases.

Primary and secondary nation-wide surveys were designed to estimate the prevalence of Meniere's disease. In the primary survey, questionnaires were sent to 4, 038 clinics in hospitals with more than 200 beds throughout Japan; 1, 049 otolaryngology, 1, 834 internal medicine, 685 brain surgery, 262 neurology, 138 psychosomatic medicine and 10 geriatric medicine clinics. The questionnaire simply requested the number of patients with Meniere's disease in each clinic. To clarify the epidemiological picture of Meniere's disease, the secondary survey was carried out in the clinics which responded to the primary survey. The secondary survey included the name, sex, birth date and other necessary items. The primary and secondary nation-wide surveys reported a total of 7, 073 cases of Meniere's disease in Japan. The prevalence rate 5.8 per 100, 000, 1.6 times higher in female than in male. It was highest in the 6th decade, followed by the 5th, 4th and 7th.

The Kitahara endolymphatic sac operation was performed on 162 cases of Meniere's disease between 1968 and 1983. 140 of these cases were observed for periods of 24 months and upward to ascertain the effectiveness of this surgical procedure. Results were classified according to the AAOO (1972) and AAO-HNS (1985) criteria. According to the AAOO criteria, 78% of the cases showed an absence of definitive spells. According to the AAO-HNS criteria, 78% of the cases showed complete control of definitive spells, and the remaining 22% showed some degree of improvement. In 85% of the cases no hearing loss was observed.These results suggest that the Kitahara endolymphatic sac operation is effective in the treatment of both frequent vertiginous attacks and bilateral Meniere's disease.Problems with the criteria are also examined.

The purpose of this experiment was to clarify the pattern of physiological change in the inner ear during the development of endolymphatic hydrops. Endolymphatic hydrops was experimentally induced in 67 guinea pigs by the introduction of silver nitrate into the endolymphatic sacs. The animals were sacrificed 1 day to 6 weeks later, and HE stained serial sections were made of their temporal bones. The endolymphatic spaces were examined under a light microscope and measured by computer to determine the pattern of size changes. The results were as follows :1) The saccule displayed the greatest degree of hydrops, with the saccules of the treated guinea pigs dilating to 7 times the size of the saccules in the control group.2) Cochlear hydrops developed principally in the upper turns during the first 3 weeks, and in the lower turns during the second 3 weeks. The final result was an even degree of dilation throughout the cochlea to a size 2.5 times normal.3) The utricle, which had been thought to display minimal dilatation, showed nearly the same degree of bulging as the cochlea : 2.5 times normal at 6 weeks.