Postural control mechanism and risk factors for accidental falls were studied in elderly persons. Posturography measurement was performed with vibration to stimulate calf muscles at different frequencies from 20, 40, 60, 80, to 100 Hz arranged in a pseudo-random fashions.
Sway velocity was measured to reflect postural control under visual and non-visual conditions with and without vibration. Under non-visual conditions, sway velocity was increased in elderly persons. In elderly persons, postural stability was controlled much more by visual input than by referents due to deterioration of vestibular and proprioceptive control of posture. Romberg's quotient in elderly who fell frequently (fallers) differed significantly from that of those who did not fall frequently (non-fallers) (P<0.01).
Fallers did not use visual input to control their posture. Proprioception from calf muscles was poorer in fallers than in the non-fallers.
In risk factor analysis, lateral body sway, Romberg's quotient, poor vision, support, motility, parkinsonism and muscle hypotony were predictive for accidental falls.To prevent falls, rehabilitation programs should be attempted to enhance proprioreceptor or pressoreceptor cues. Visual input should be promoted by sufficient visual illumination and contrasting visual surroundings.

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Pendular rotation test in a head-tilted position was performed with a stimulus mode; amplitude=360 degrees, frequency=0.1 Hz, and maximal speed=114 deg/sec. The subject's head was tilted 60 degrees backward from the upright position, and then rotated 45 degrees either to the left or right. Using this test procedure, it was possible to evaluate the excitability of vertical semicircular canals, using infra-red CCD camera and a personal computer to analyze nystagmus.
There were no significant differences in the maximal slow phase eye velocity (SPEV) or in the maximal amplitude of vertical nystagmus from the anterior or posterior semicircular canal in normal adult subjects. However, a significant difference in the maximal SPEV of vertical nystagmus was found between the anterior semicircular canal and posterior semicircular canal in elderly subjects over 70 years old. Excitability of the posterior semicircular canal was lower than that of the anterior semicircular canal in these elderly subjects. Moreover, excitability of the posterior semicircular canal in elderly persons was lower than that in normal non-elderly subjects.

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We studied properties of adaptive gain control in the saccadic system in 7 normal subjects. Subjects were asked to look at a target which moved in steps of random amplitude of 20 or 30 deg. In the present study, the target eccentricity was changed by a constant percentage (60%) during each saccade aimed at the target. At the beginning, a primary saccade was induced toward the first target position, and a second saccade triggered by a second target step subsequently occurred in the direction of the second target. After repeated trials of the stimulus, the amplitude of primary saccade gradually decreased and finally the eyes caught the second target with a single saccade. The amplitude of the primary saccade was measured and the percentage of saccadic amplitude (accuracy) was defined relative to the amplitude of the first target step. The accuracy was gradually decreased during the course of the experiment and in the course of hundred repetitions, the accuracy approached 60%. Subjects did not detect intrasaccadic target displacements because visual sense was suppressed during saccadic eye movements. Therefore, the reduction of saccadic amplitude was not the result of a conscious strategy, but adaptive gain control that must originate in the saccadic system.

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We investigated chemical blood flow regulation in the brainstem and inner ear in rats. To evaluate the efficiency of chemical regulation, we observed the response of brainstem blood flow (BBF) and cochlear blood flow (CoBF) to hypercapnia and hypoxia using laser-Doppler flowmetry. Both BBF and CoBF increased in response to hypercapnia, showing a decrease in total vascular resistance. The result supposed the existence of chemical regulation in both the brainstem and inner ear. BBF and CoBF were maintained in response to hypoxia and consequent hypotension, also showing decrease in total vascular resistance. The brainstem showed stronger vascular response than the inner ear, and we concluded that chemical blood flow regulation in the brainstem was more efficient than that in the inner ear.

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We analyzed data collected from 134 patients (37 males and 97 females) with dizziness and/or vertigo who were confirmed to have orthostatic dysregulation (OD) based on a questionnaire survey between December 1990 and November 1994. The patients ranged in age from 10 to 80 years with a mean age of 42.5 years for males and 44.6 years for females. Patients with OD consulted our clinic more frequently in summer than in the other seasons.
Orthostatic dizziness was the most common manifestation among the major symptoms of OD and was noted in 116 of 134 patients (86.6%). Fatigue was the most frequent complaint among the minor symptoms of OD and was noted in 97 of 134 patients (72.4%).
OD was noted in 47 patients (35.1%) with dizziness or vertigo of unknown origin, in 22 (16.4%) of those with Meniere's disease, in 18 (13.4%) with dizziness or vertigo from central disorder, in 14 (10.4%) with hypotension, and 33 (24.6%) of those with other disorders.
As for the positive rate on Schellong test, patients with OD and control subjects, showed 49.2% and 27.8%, respectively, and this difference was significant.
These results suggest that autonomic imbalance suspected from the OD questionnaire and the Schellong test results probably affects the occurrence of vertigo and/or dizziness.

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We examined dizzy patients with orthostatic dysregulation (OD) using the Schellong test, the Cornell Medical Index-Health Questionnaire (CMI) and the Yatabe-Guilford Personality test (Y-G test). Subjects were 134 patients (37 females and 97 females) who were confirmed to have OD based on a questionnaire survey conducted from December 1990 to November 1994.
Systolic and diastolic pressures in the supine position in female patients with OD were lower than those in normal subjects. This tendency became more evident with advancing age.
Of 17 males with OD, seven (41.2%) were types III or IV on the CMI, and seven (41.2%) were types B or E in the Y-G test which suggested mental and/or emotional "instability". Of 52 females with OD, 26 (50.0%) showed types III or IV on the CMI, and 19 (42.2%) were types B or E on the Y-G test. These results suggest that autonomic imbalance suspected on both the OD questionnaire results and the Schellong test is probably related to the occurrence of vertigo and/or dizziness, and that there is some correlation between OD and emotional and/or psychosomatic instability.

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The clinical application of CT scan and MRI together with the progress of neurootological examinations has changed the clinical profile of acoustic neuromas. The clinical records of 102 patients with acoustic neuroma examined at the University of Tokyo Hospital between 1984 and 1993 were reviewed. Patients seen between 1989 and 1993 showed smaller tumor size, lower incidence of neurological signs and central neuro-otological findings, and shorter diagnostic delay than those between 1984 and 1988. Small and early tumors with changed profile and few symptoms must not be overlooked.

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The efficacy of treatment in vertigous attacks and hearing loss in Meniere's disease has been evaluated according to AAO-HNS (1985) criteria.
However, the Committee of the Japan Society for Equilibrium Research proposed preliminary guidelines for reporting treatment results in Meniere's disease in 1994.
In the present report, we compared the guidelines of the Committee of the Japan Society for Equilibrium Research with that of modified AAO-HNS (1985).
The results of evaluation 12 months after the initiation of treatment were similar to those after 24 months. The former evaluation was superior to the latter because there were fewer dropouts. Hearing levels were assessed from the three frequency pure-tone average (PTA) at 500 Hz, 1 kHz, 2 kHz. If pre and post treatment hearing levels were evaluated using the poorest hearing level in the follow-up periods, there was no significant difference between treatment results evaluated using the guidelines of the Committee of the Japan Society for Equilibrium Research (PTA: 250 Hz, 500 Hz, 1 kHz, 2 kHz) and those using the modified AAO-HNS guidelines (PTA: 500 Hz, 1 kHz, 2 kHz).
Because there are some cases with contradictory results between vertigous attacks and hearing level, new methods should be determined for evaluating overall treatment results in Meniere's disease.

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An autopsy case of late cortical cerebellar atrophy (LCCA) is reported. A 58-yearold male without family history developed dysarthria and gait disturbance. Neurological examination revealed scanning speech, bradylaria and gradually progressive cerebellar ataxia of the trunk and all limbs. Clinical test for his eye movement showed both saccadic dysmetria and loss of smoothness in pursuit eye movement, but no nystagmus. His deep tendon reflexes remained normal except for decrease in ankle tendon reflex. There were no mental deterioration, nor dysautonomia. He died of sepsis at the age of 73. The duration of his illness was approximately 15 years. Neuro-otological findings were as follows; 1) On eye tracking test, horizontal pursuit eye movements were disturbed, but the severity of this disturbance was initially very mild and deferiorated slowly. 2) Rapid eye movement system such as saccade was normal. 3) No apparent gaze nor spontaneous nystagmus was revealed. 4) Optokinetic nystagmus were normally evoked in number, and the maximal slow phase velocity was almost normal range.
On neuropathological examination, mild cerebellar atrophy of both the vermis and cerebellar hemispheres were shown macroscopically. There was severe deciduation of Purkinje cells in both the cerebellar vermis and hemispheres in microscopic examination. However, neurons of the inferior olivary nuclei were almost normal in number, although, slightly decreased in size. The molecular layer and cerebellar white matter showed no abnormalities. Neurons among the granular layer, the dentate nuclei, pontine nuclei and various nuclei of the brain stem showed a normal appearance.
In conclusion, the characteristics of abnormal eye movement in cases that have been pathologically diagnosed as LCCA are disturbance of smooth eye movement system and normally evoked optokinetic nystagmus. We thought the neuropathological findings confirmed these results from a neuro-otological perspective.

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Na-K ATPase in the stria vascularis is known to participate in the active transport of Na⁺ and K⁺ ions, and plays essential role in producing cochlear endolymph. The mechanisms that control or maintain the stria vascularis function, however, remain unclear. In the present study, the K-NPPase activity, the second component of the Na-K ATPase complex, in the marginal cells was cytochemically investigated after reserpine and L-threo-DOPS administration. K-NPPase activity was completely inhibited after treatment with reserpine, whereas, following reserpine and L-threo-DOPS treatment, enzyme activity was detectable. As reserpine is an adrenergic neuron blocker, and L-threo DOPS is the precursor of L-noradrenaline, noradrenaline converted from L-threo DOPS was able to restore K-NPPase activity in the reserpine-treated animals. The present result suggests that catecholamines may play an essential role in the maintenance or control of the Na-K ATPase activity, and that the stria vascularis may be one of the target organs of catecholamines.

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Twenty-six patients with cerebellopontine epidermoid tumor underwent radical surgical resection between 1985 and 1992 in Mitsui Memorial Hospital. Tokyo.
The average age was 46.1 years and the male to female ratio was 1 : 1.36. Common clinical manifestations included trigeminal pain, facial hypesthesia, dizziness and tinnitus. Predominant signs were cranial nerve palsies and cerebellar impairment. Pure tone threshold was stored comparatively, but there was a significant difference between the unaffected and affected side in high tones (4.000 Hz, 8.000 Hz).
The maximal discrimination score was within the normal range, but all results showed retrocochlear findings in ABR. Three patients presented spontaneous nystagmus, four had dysmetria. Caloric test results were comparated. Anatomical site and growth of the tumors was discussed.

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Using autoradiography with ³H-thymidine, the effect of transforming growth factor (TGF)-alpha was studied after culturing utricles of mice for 7 days. Cell proliferation was induced in the sensory epithelium by TGF-alpha. Compared with utricles cultured for 3 days, many labeled cells were detected in the hair cell layer of the sensory epithelium of utricles cultured for 7 days. These observations suggest that stimulation of the EGF receptors by TGF-alpha binding stimulates cell differentiation as well as cell proliferation in the mature mammalian vestibular sensory epithelium.

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Two tests were administered to four groups of patients: the Cornell Medical Index (CMI) and the Manifest Anxiety Scale (MAS). Group I consisted of vertigo patients 65 years of age and older; group II, vertigo patients less than 65 years of age, group III healthy persons 65 years of age and older, group IV healthy persons less than 65 years of age. The second, third and fourth groups served as controls.
1. In the same patients, CMI and MAS test results showed no significant difference when tested during vertigo and during absence of vertigo, in group I and group II.
2. In group I, CMI and MAS test results showed significantly more psychosomatic problems than in group III, and slightly more psychosomatic problems than in group II.
3. It was concluded that the reason CMI and MAS test results showed more psychosomatic problems in group I and group II was because of differences caused by their individual characters.
4. It was concluded that the reason CMI and MAS test results showed more psychosomatic problems in group I was because of differences caused by their individual characters and ages.

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