Epidemiological and clinical characteristics of Menière's disease in Japan.

From 1975 to 1990, nationwide surveys on Menière's disease were performed three times by the Research Committee of Menière's disease (1975-76) and the Research Committee of Peripheral Vestibular Disorders (1982-84 and 1990) in Japan. Nine hundred and fifty-eight definite Menière cases, 520 in the 1st, 230 in the 2nd and 148 in the 3rd survey, were sampled by the members of the Committees. The epidemiological and clinical characteristics of Menière's disease were analyzed and compared with such control cases as other vertiginous patients, ENT patients without vertigo, and healthy subjects. In Menière's disease, the male to female ratio has changed from even to female predominance over the 15 years the study ran. The age distribution at onset peaked in the forties for males and thirties for females. Significant epidemiological results are summarized as follows: Definite Menière's disease has a higher incidence in married persons and in people with a nervous and precise character, whereas the incidence is lower in obese people. Physical and mental fatigue induced the onset of attacks. Menière's disease happened in day time in many cases, especially during the afternoon. As these epidemiological findings were commonly observed in all the surveys, the results are considered to be universal epidemiological characteristics of Menière's disease in Japan. In the same period, regional investigations were performed by Toyama Medical Association and our University. The male to female ratio in Toyama indicated a more significant female predominance than in the nationwide surveys. The prevalence of Menière's disease in Toyama Prefecture has been almost constant in all surveys, about 17/100,000 since 1974.(ABSTRACT TRUNCATED AT 250 WORDS)

Human and animal semicircular canal function during circular walking.

It is generally accepted from animal studies that the medial vestibulospinal tract originates in the medial vestibular nucleus, which is supplied from the semicircular canals, and descends only to the upper thoracic levels of the cord. In humans, however, there is some indirect evidence to support the concept that impulses from the semicircular canals reach the lumbosacral cord and influence lower as well as upper extremity activity.

Clinical evaluation of medical treatment for Menière's disease, using a double-blind controlled study.

There are great variations in the clinical evaluations of the effectiveness of antivertiginous drugs for Meniere's disease. In our clinical evaluation, subjective and objective signs and symptoms of 128 patients with Meniere's disease and of 98 with other peripheral vestibular disorders were analyzed in a double-blind controlled study comparing adenosine triphosphate (ATP) (300 mg) and betahistine (36 mg) each given daily for 4 weeks. The method of administration was the matched-pair-group-method for this double-blind controlled trial. The attending physicians concluded that ATP was significantly more effective than betahistine in the treatment of Meniere's disease and other peripheral vestibular disorders.

Modulation of the visuo-ocular reflex by the vestibulo-ocular reflex in peripheral vision.

Peripheral OKN was produced by stimulating the visual field with a special device, designed by Miyoshi et al. Stimuli to induce peripheral OKN and rotatory nystagmus (RN) were applied to the same subject simultaneously. The results obtained were as follows. 1) In the case of the whole visual field, with a target velocity of 30 degrees/sec the combined slow-phase velocity of OKN and RN was also a constant 30 degrees/s in any phase of rotation of the subject and with any combinations of the rotationary directions of subject and target. 2) In the case of the peripheral visual field; when both OKN and RN were in the same direction, the slow-phase velocity of the combined OKN was 10-20% greater than that of the peripheral OKN alone. However, the combined OKN never exceeded the velocity of the target. In contrast, when OKN and RN directions were opposed, combined OKN was correspondingly decreased by about the same 10-20% amount.

Vertigo due to whiplash injury: a neurotological approach.

A series of examinations were carried out to elucidate the characteristics of vertigo due to whiplash injury. In patients with whiplash injury, there are over-excitation of the cervical and/or the lumbar proprioceptors on one hand, and dysfunction of the central nervous system, such as the hypothalamus, the brain stem and the cerebellum, on the other hand. These two etiological factors induce disequilibrium by a trigger-and-target relationship in which the above proprioceptors act as a trigger and the central nervous system acts as a target. This postulate is applicable to the explanation of aural vertigo following whiplash injury. Autonomic reflexes in patients with whiplash injury can be explained not only as due to over-excitation of the cervical sympathetic nerves, but also to that of the cervical and lumbar proprioceptors. In other words, these reflexes are considered as being the proprio-autonomic reflexes. These reflexes are more evident in patients with cervical pain. Cerebellar symptoms can be manifested by over-excitation of the cervical and lumbar proprioceptors. These symptoms are more evident in patients with lumbar pain. The above differences in the autonomic reflexes and cerebellar symptoms of patients with cervical and/or lumbar pains can be explained on the basis of known fiber connections in the central nervous system. Hypertonicity of the cervical and lumbar erector muscles in patients with whiplash injury can be explained not only as due to over-excitation of gamma fibers, but also to that of sympathetic nerves in these muscles. This hypertonicity affects the central nervous system, causing disequilibrium following whiplash injury.

Internuclear fiber connections of vestibular nuclear complex. A horseradish peroxidase study.

Internuclear fiber connections among the superior (SVN), lateral (LVN), medial (MVN) and descending (DVN) vestibular nuclei were examined in cats using retrograde transport of horseradish peroxidase (HRP). HRP was microiontophoretically applied in the respective vestibular nucleus at doses of 300-500 nA for 5-10 min, and with the treatment the HRP injection site was limited to 0.2-0.5 mm in diameter within the nucleus. Major commissural connections were found between the bilateral SVN and between the bilateral DVN. Minor commissural connections were observed from MVN to SVN, LVN and MVN, from DVN to LVN, and from LVN to the contralateral LVN. In the ipsilateral vestibular nuclei, fiber connections were found from LVN to SVN, from MVN to SVN, LVN and DVN, and from DVN to SVN and LVN.

Role of the visceral brain in body equilibrium.

A series of examinations were carried out to determine whether the limbic system, particularly the hippocampus and the amygdaloid nucleus, participates in the production of disequilibrium of the eyes and the body and to clarify the conditions which induce disequilibrium. Over-stimulation of the rabbit's hippocampus induces over-excitation of adrenergic components involved in this part of the brain, through which dysfunction of equilibrium center in the brain stem is eventually brought about. This dysfunction leads to disequilibrium of the eyes and the body. On the basis of these results, equilibrium tests for neurotic vertigo were devised. Using these equilibrium tests we noted that in a certain group of traumatized patients who suffer from vertigo of psychosomatic origin, there are two etiological factors: functional linkage between the temporal cortex and the limbic system, particularly the hippocampus in regard to a memory or a conditioned reflex relevant to vertigo, over-excitation of the adrenergic components involved in the brain connecting the hippocampus, the hypothalamus and equilibrium centers in the brain stem. These two etiological factors induce disequilibrium by a trigger-and-target relationship in which the former acts as a trigger and the latter as a target. The cerebellum is not an essential factor in producing vertigo of psychosomatic origin, but it enhances vertigo of this type through activation of the adrenergic components, particularly those in the hippocampus. Thus, in patients with both vertigo of psychosomatic origin and cerebellar symptoms recovery from vertigo tends to be delayed. Over-stimulation of the rabbit's amygdaloid nucleus, particularly its medial portion and the habenular nucleus induces over-excitation of adrenergic components involved in these parts of the brain. These animals develop disequilibrium of the eyes in response to an olfactory stimulus, such as extract of garlic. On the basis of these results, equilibrium tests for olfactory vertigo were devised. Using these equilibrium tests we noted that traumatized patients who suffered from vertigo due to inhalation of garlic vapor showed hyper-reactivity to adrenaline and developed disequilibrium of the eyes and the body when given a subcutaneous injection of this drug. These findings indicate that olfactory vertigo is induced by a mechanism in which olfactory stimulation affects the above adrenergic components, causing disequilibrium of the eyes and the body.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of the cervical and lumbar proprioceptors during stepping. An electromyographic study of the muscular activities of the lower limbs.

To obtain evidence of the role of the cervical and lumbar proprioceptors during stepping, the following investigations were carried out. 1) 10 normal, healthy subjects and vertiginous patients, particularly those with lumbar pain, were examined. 2) Fukuda's stepping test was first carried out, followed by two modified stepping tests, i.e., stepping after fixing the waist with a corset and after fixing the neck with a collar. 3) Electromyograms (EMGs) of the gastrocnemius muscles of the extensor of the lower limbs were analysed as regards the foot contact with the ground. The following results were obtained. In the original way of Fukuda's stepping test, normal subjects tended to show EMG discharges from the gastrocnemius muscles before foot contact with the ground, whereas in the modified stepping tests, the generation of EMG discharges was delayed, especially in the test requiring fixing of the waist with a corset. The results of these stepping tests were reversed in the vertiginous patients, particularly in those with lumbar pain. We conclude that the lumbar proprioceptors participate especially in the smooth performance of stepping by promoting the anticipatory activity of the extensor of the lower limbs.

Effects of pure-tone sound, impulse noise, and vibration on visual orientation.

Eye movements and the electroencephalogram (EEG) were recorded in intact rabbits during an optokinetic test when the animals were exposed to pure-tone sound (85 dB at 4,000 Hz), impulse noise (159 dB), and vibration directed to the abdomen (at an amplitude of 0.9 mm at frequencies of 40 to 140 Hz). The frequency and velocity of optokinetic nystagmus significantly increased in response to these stimuli. The increase seen with vibration was greater than that resulting from sound, and the response was strongest when sound and vibration were combined. The increase of optokinetic nystagmus seen with induced vibration was progressive and dependent on the frequency. The increase was weakest during vibration at 40 Hz and strongest during vibration at 140 Hz. Electroencephalograms (EEGs) of the amygdaloid complex, dorsal hippocampus, midbrain reticular formation, and frontal motor cortex all were activated during exposure to sound and vibration, but activation of the hippocampal EEG was most closely related to the increase of optokinetic nystagmus. During optokinetic tests, impulse noise regularly triggered nystagmic beats. When the rabbits were not in the test apparatus, nystagmus was produced in response to about 18 per cent of the presentations of impulse noise, while activation of the EEG was constant. Thus, vibration and noise, when excessive, may interfere with visual orientation and hence disturb equilibrium. These findings can be related to the nonspecific dizziness that occurs in aerospace or industrial workers exposed to excessive noise and vibration.

Enhancement of eye motor response and electrical brain activity during noise and vibration in rabbits.

The relationship between electroencephalogram (EEG) and eye movements was studied in rabbits during optokinetic, vestibular, and optovestibular tests. EEG was recorded through permanently implanted electrodes. Exposure to noise and vibration increased the frequency and the velocity of optokinetic nystagmus (OKN). The increase was greater during vibration but greatest during combined noise and vibration. EEG activity was closely linked to changes in OKN and was particularly evident with the appearance of theta waves in the dorsal hippocampus. Also, rotation of the rabbit produced considerable activation in the EEG.