The perilymphatic fistula (PLF), defined as an abnormal communication between the inner and middle ear, presents a symptomatology of hearing loss and vestibular disorders that is indistinguishable from a number of other inner ear diseases. The methods for diagnosis remain controversial. We have shown that the protein, Cochlin-tomoprotein (CTP), was selectively detected in the perilymph and established a definite diagnostic test for PLF using CTP as a biochemical marker, and have proved high reliability of the diagnostic performance of the test. In the Japanese PLF study group, the diagnostic criteria proposed in 1983 were revised. The definite diagnosis criterion is now based on the visual identification of the fistula (not a leakage) and/or detecting CTP from the middle ear lavage (MEL). We describe herein and discuss the summarization of the characteristics of PLF revealed by our CTP detection test.

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The aim of the present study was to summarize the clinical feature of the perilymphatic fistula. Charts of 249 patients with various ear symptoms followed by exploratory tympanotomy were retrospectively analyzed. In 23% of patients a visible fistula in the round or/and oval windows was identified. The majority of patients reported a history of pressure elevation and minor head injury. Vertigo improved in 82% of the patients and the hearing loss in 11% of the patients. Methods of diagnosis of perilymphatic fistula still remain controversial. This manuscript also reviews the various diagnostic methods such as the high-resolution computed tomography, magnetic resonance imaging (MRI), and CTP.

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The present study was undertaken to develop the method of diagnosis of vertigo with analysis of nystagmus in rapid eye movement (REM) sleep. Seven inpatients with vertigo (2 males and 5 females; 39.7±12.7 years (mean±SD)) participated. They underwent electronystagmography assessment in their night sleep. During Non-REM sleep, the nystagmus of all patients with peripheral vertigo disappeared except stage 1. During REM sleep, rapid eye movements (REMs) of all patients were recorded. Almost all of the patients with peripheral vertigo showed a larger value of REM density towards the direction in the awake state than the other. The findings of our study led us to hypothesize that the analysis of eye movements during nocturnal sleep may be useful for evaluating the vestibular nuclei function.

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Acute sensorineural hearing loss with vertigo due to vascular events in the vertebrobasilar system is diagnostically challenging, especially if signs of central nervous system involvement are minimal. We report herein on the clinical course and diagnostic process of a 60-year-old woman who presented with acute sensorineural hearing loss and vertigo caused by a dissecting aneurysm in the vertebral artery. Brain magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), single-photon emission computed tomography (SPECT), and a lumbar puncture revealed a dissecting aneurysm in the left vertebral artery with no evidence of ischemic lesions or subarachnoid hemorrhage. Dysfunction in the cerebellum was suggested by saccadic pursuit and truncal ataxia. The patient underwent anticoagulant therapy for 1 year, following which the isolated cavity of the dissecting aneurysm reduced in size as observed on brain MRI. In addition, significant improvements were seen in her gait and hearing level. The patient can now walk normally and has suffered no relapse of symptoms. (152 words)

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Frequency analysis of the sway of the body center of gravity appearing in the upright standing posture is important as one of the measurements in stabilometry. However, although analysis using the FFT method is now widely used, it is difficult to interpret the results. Therefore, using MEM method, we made a scatter diagram showing the frequency on the x-axis and the spectral peak area on the y-axis. In the scatter plot, we filled in the power law distribution curve and the approximate expression. This diagram (the peak-area spectrum) was the object of this study. The results obtained were as follows.
1) In healthy cases, the area spectra showed the power law distribution. 2) In a case with labyrinthine failure, the spectrum showed an increase of the area of the maximum peak frequency. We considered the finding is caused by a disorder of the labyrinthine righting reflex. 3) In a case with cerebellum disturbance, irregularities were observed in the power law distribution of the peak areas. The findings are interpreted as due to a coordination disorder in standing posture regulation. 4) In a case of Parkinson's disease, the slope of the power law distribution curve became flat. The findings are interpreted as due to postural control disorder caused by muscle rigidity.
Examination of the peak area spectrum is useful for quantitative assessment of the body sway in an upright standing posture.

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Development of 3-tesla enhanced magnetic resonance imaging (MRI) provides a tool for the visualization of endolymphatic hydrops (EH). This technique was first developed in animal experiments and adapted in patients with inner ear diseases including Meniere's disease (MD). Up to the present, we have demonstrated EH in many MD patients. Recently, we have succeeded in obtaining a 3D-real IR-like image even after intravenous standard-dose gadolinium administration. This type of image was named the HYDROPS (HYbriD of Reversed image Of Positive endolymph Signal and native image of positive perilymph signal). The relationship between unilateral MD and EH has not yet been explored. We studied 76 patients with unilateral MD who were evaluated using MRI. The mean age of the subjects was 53.4 years (range 17 to 80 years). Forty-two were women and 34 were men. Symptomatic and non-symptomatic ears were categorized into 4 groups (healthy, 76; possible, 48; Probable, 13; and definite, 15) based on AAO-HNS definitions. MRI was performed 4 hours after intravenous gadolinium administration. Overall, 152 ears were evaluated. EH in the cochlea was present in 57 of 76 symptomatic ears (73.7%) and 34 of 76 (44.7%) non symptomatic ears. Ears with definite MD had EH more frequently in the cochlea than ears in the healthy ears groups. Furthermore, EH in the vestibule with definite MD was larger than ears in any of the other groups. Our reports showed for the first time that there was Ba relationship between the degrees of EH and the stage of MD. Moreover, in fewer than half of unilateral MD patients EH was seen in the cochlea with non-symptomatic ears. EH in healthy ears may be an indicator of bilateral MD. Using MRI to identify this covert EH in asymptomatic patients may offer the possibility of early detection or prevention of MD.

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Wistar rats were intraperitoneally injected with 0.02 units/g of AVP (Pitressin; Arg-vasopressin. Daiichi-Sankyo, Japan) in all the experiments in this study. ABR thresholds gradually increased significantly up to 60 min after the injection. When dehydration load pretreatment for 24h was added, ABR thresholds rapidly increased significantly up to 10 min after the injection. However, the morphological endolymphatic hydrops in the cochlea was not detected under light microscopy. On the other hand, the enlargement of an area lacking intracellular organelles in the intermediate cells in the stria vascularis or a so called “vacuole” was detected under transmission electron microscopy after the AVP injection. When the dehydration load pretreatment for 24h was added, the vacuole area increased with AVP injection. However, when a V2R antagonist (OPC-31260, donated by Otsuka Pharmaceutical) was administered before AVP, vacuole formation was suppressed significantly. Conversely, vacuole formation was not suppressed when a V1aR antagonist (OPC-21268, donated by Otsuka Pharmaceutical) was administered before AVP injection. As a clinical application based on above mentioned basic studies, we conducted hydration therapy for Meniere's disease. In the hydration therapy, basically the patients drank 35 ml/kg/day of water daily in addition to the normal daily beverages and foods for 2 years. Medication of 21 g was given whenever a vertiginous spell or hearing loss or aural fullness reoccurred. The outcomes were determined according to the criteria of the AAO-HNS 1995 guidelines. In the hydration therapy group, the definitive spells were controlled in 93% of the patients. The hearing in the hydration therapy group was improved significantly in comparison with the conventional therapy group.

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Some sicknesses are well known to be provoked by inadequate adaptation to physical and/or psychogenic stress in daily life. Attacks of Meniere's disease characterized by vertigo, fluctuating hearing loss and tinnitus due to inner ear pathology represent a common example. Furthermore, this disease has been proposed to especially occur in civilized people living a stressed lifestyle, i.e. “Menierization is civilization”. However, it is very difficult to prove a significant relationship between stress and inner ear pathology, since the definition of stress is too obscure for scientific analysis of these aspects. Since the oto-pathology in Meniere's disease was first revealed to be inner ear endolymphatic hydrops through temporal bone studies in 1938, it has gradually become understood that inner ear endo-organ tissues, including the endolymphatic sac, prepare the fluid homeostatic system via water metabolism-related molecules such as vasopressin and aquaporin. Subsequently, it was proposed that the pathogenesis in Meniere's disease could be inner ear endolymphatic hydrops due to a disorder of water metabolism-related molecules. In the present paper, we would like to discuss the neuroscientific relationship between stress and inner ear pathology by reviewing plasma vasopressin (an anti-diuretic stress hormone) and its receptor, V2 receptor, in the endolymphatic sac (an inner ear endo-organ for endolymph absorption) in patients with Meniere's disease.

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A histopathological feature of Meniere's disease is endolymphatic hydrops. Furthermore, a human temporal bone study has revealed that the endolymphatic sac showed fibrosis and/or hypoplasia in a patient with Meniere's disease. Based on this histological finding, malfunction of the endolymphatic sac may cause endolymphatic hydrops. However, it is impossible to explain the fluctuation of Meniere's symptoms with this retention hydrops, so the mechanisms underlying the endolymphatic hydrops of Meniere's diseases is still unclear. Clinically, it is well known that stress aggravates the condition of Meniere's disease. It seems to be that there are some relationships between stress and endolymphatic hydrops. Endolymphatic hydrops could be taken as malfunction of water homeostasis in the inner ear. If this is the case, one of stress hormones, vasopressin, could regulate water homeostasis in the inner ear. Actually, plasma vasopressin levels have been reported as elevated in patients with endolymphatic hydrops including Meniere's disease. Experimentally, vasopressin type 2 receptor was expressed in the basal cell of the stria vascularis. Moreover, the water channel of aquaporin (AQP) 2, the relocalization of which is regulated by vasopressin, was also expressed in the stria vascularis. Further, other AQPs were also expressed in the stria vascularis. To investigate the effect of vasopressin on the inner ear, vasopressin was administered to rats or guinea pigs. Vasopressin induced enlargement of the intrastrial space and endolymphatic hydrops. These results indicate that vasopressin affects the stria vascularis and endolymphatic hydrops was induced as a consequence. The following is a summary. Basically, patients with Meniere's disease have malfunction of the endolymphatic sac with retention hydrops. If the patients are under stress, the secretion of vasopressin would increase. The increase of vasopressin level causes the enlargement of the endolymphatic hydrops. These conditions may induce the symptom of Meniere's disease. Based on these clinical and experimental results, we produced a new animal model for Meniere's disease with vestibular disorder.

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