In a study of the regional differences in susceptibility to damage of the vestibulo-semicircular canals caused by labyrinthine lesions produced by four different procedures, namely, by an intracranial approach, through the middle ear, through the facial nerve and by means of experimental endolymphatic hydrops, the following results were obtained. 1. The crista of the posterior semicircular canal among the semicircular canals and the macula of the saccule within the vestibule were the most susceptible to impairment. In other words, the most susceptible region was the so-called pars inferior. 2. It was considered that, in such an impairment that vacuololike changes of the sensory epithelium would be improved and the cupulas would be reconstructed, the caloric nystagmus would also be provoked again.
The frequnency of occurrence, location and course of the branch of the singular nerve in the otic capsule in man was investigated by examining histological sections of 223 human temporal bones. In the proximal portion near the internal auditory meatus the branch of the singular nerve was observed in 194 bones, and was seen to join the main trunk of the singular nerve in 181 of those bones. In the distal portion near the posterior semicircular canal ampulla the branch was observed in 58 bones and in 45 of those bones it was seen to arise directly from the main trunk of the singular nerve. In 13 bones the branch was seen to be taking its course in the otic capsule independently from the main trunk all the way to the posterior canal crista. The accessory portion of the branch of the singular nerve reached the dura mater of the posterior cranial fossa near the internal auditory meatus in 11 of 223 bones. Patients with dizziness often complained of vertigo and headache. The problem seems to be originated in the dural branch of the singular nerve.
Horseradish peroxidase (HRP) was iontophoresed neurons were recognized in the lateral reticular nucleus (of the side ipsilateral to the injection site), dorsal cap of the inferior olive (contralateral), inferior central nucleus of the raphe (bilateral), superior central nucleus of the raphe (bilateral), caudal part of the dorsal nucleus of the raphe (bilateral), vestibualr nuclei (bilateral), and nucleus reticularis tegmenti pontis (bilateral). Electrical stimulation of the caudal part of the dorsal nucleus of the raphe (DNR) elicited orthodromic-evoked potentials with a latency of 2-2.6 msce in the cerebellar flocculus and the positions of stimulating electrode where the threshold current was lower than 150μA were limited to a small area corresponidng well with the caudal part of the DNR. Electrical stimulation of the cerebellar flocculus elicited antidromic unitary responses with the latency of 1.2-1.3msec in the caudal part of the DNR. The latency and the synaptic delay in the flocculus corresponded well with that of the orthodromic evoked potentails. These findings of the present study strongly suggest that there exists floccular afferent projections from the caudal part of the DNR.
The effect of electrical stimulation of neck afferent on the forelimb extensor (triceps) and flexor (biceps) monosynaptic reflex (MSR) was investigated in chloralose-anesthetized, decerebrated or spinal cats. In chloralose-anesthetized cats, ipsi-and contralateral stimulations of the C2 dorsal root ganglia produced early facilitation (10-30 msec) followed by late inhibition (50-100 msec) in both triceps and biceps MSRS. In decerebrated cats, however, the same cervical volleys induced the reciprocal effect; facilitation (30-150 msec) in triceps and inhibition (30-70 msec) in biceps MSR. In spinal cats, ipsilateral C2 dorsal root ganglion stimulation produced early excitation only with 10 msec in both triceps and biceps-MSRS, but the effect of contralateral C2 dorsal root ganglion stimulation was smaller and sometimes absent. Intracellular recordings from triceps and biceps motoneurons were performed to elucidate the synaptic mechanism of the above mentiond effect of the neck. In choloralose-anesthetized cats, ipsi-and contralateral stimulations of C2 dorsal root ganglia induced EPSPS, IPSPS, and also mixed PSPs in triceps and biceps motoneurons. A similar pattern of PSPs occurred in spinal cats, and temporal summation was clearly observed. In decerebrated cats, sometimes the same cervical volleys produced small EPSPs followed by late, long-lasting depolarization in triceps motoneurons. The latency distribution of PSPs revealed that the synaptic linkage between the neck afferents and the forelimb motoneurons was apparently polysynaptic. The elementary synaptic circuits for the neck reflex seem to be located in the spinal cord. The brain stem structures, however, are indispensable for the reciprocal effects on forelimb motor activities.
Optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN) were investigated in Japanese monkeys (macaca fuscata). Although the OKN basically resembled that in the rhesus monkey, a lower adaptation limit of OKN velocity (about 40-60°/sec) and longer rise time to reach the maximum eye velocity after the onset of stimulation (about 30 seconds on average) were observed. Turning off the lights induced the first and second phases of the OKAN, and occasionally the third or fourth phases were induced. While an increase in the stimulus speed changed patterns of OKAN decline from an almost straight to catenary-like or sinusoidal fashion, the total duration time of the first and second phases remained stationary (about 150-200 seconds). Various patterns of the OKAN may represent interactions between the different mechanisms inducing after-nystagmus in opposite directions.
In order to investigate the neural mechanism of olfaction-related nystagmic response, a series of experiments has been carried out where various parts of rabbits' brains received repeated electrical stimulation. The resulting changes in nystagmic responses of the animals were observed, when they were stimulated by intravenous adrenaline and inhalation of the vapor of liquid garlic. The results obtained were as follows: (1) The rabbits receiving repeated electrical stimulation of the hippocampus tended to develop and /or increase nystagmic response with intravenous adrenaline. In some of them, increase and / or decrease of nystagmic responses were also seen in response to inhalation of the vapor of liquid garlic. (2) The rabbits receiving repeated electrical stimulation of the lateral portion of the amygdaloid nucleus did not show any signs of nystagmic response with intravenous adrenaline. The same held true for inhalation of the vapor of liquid garlic. (3) One rabbit receiving repeated electrical stimulation of the septal area had an increased nystagmic response with intravenous adrenaline. This animal also had an increased nystagmic response when he was stimulated by inhalation of the vapor of liquid garlic. (4) The rabbits receiving repeated electrical stimulation of the habenular nucleus had significant development and / or increase of nystagmic response when intravenous adrenaline was given. These animals also developed similar nystagimic response with inhalation of the vapor of liquid garlic. With reference to the above-mentioned results and those from our previous animal experiments, the following conclusions were drawn: (1) The medial portion of the amygdaloid nucleus and habenular nucleus play a major role in the production of olfaction-related nystagmic response. In contrast, the roles of the hippocampus and septal area in induction of nystagmic responses due to olfaction were less obvious. No significant role of the lateral portion of the amygdaloid nucleus was attributable in the production of the nystagmus of this kind. (2) Overexcitement of adrenergic components in the central nervous system, particularly those involved in the medial portion of the amygdaloid nucleus and habenular nucleus is an important factor for the production of olfaction-related ocular dysfunction, i.e. nystagmus.
Monocular horizontal and vertical eye movements were recorded by electronystagmography (ENG) using silver plate electrodes in normal subjects. The amplitudes of horizontal or vertical eye movement were measured. Horizontal and vertical pursuit movements and saccades were recorded to measure their amplitudes. 1. Horizontal eye movement Amplitudes of the right eye=amplitudes of the left eye…55%, amplitudes of the right eye≠amplitudes of the left eye…45%. 2. Vertical eye movement Amplitudes of the right eye=amlitudes of the left eye…80%, amplitudes of the right eye≠amplitudes of the left eye…20%. In particular, the amplitudes of the horizontal right eye movement are not always equal to those of the left eye, therefore observation of ophthalmoplegia with ENG should be made very carefully.
Vestibuloocular reflex (VOR), optovestibular reflex (OVR) and cervicoocular reflex (COR) were quantitatively analyzed in 21 healthy subjects using damped pendular rotation (DPR) in the yaw plane. VOR and OVR gains showed constant values irrespective to head angular velocities; the mean VOR gain was 0.58 (SD 0.17), and that of OVR gain was 0.85 (SD 0.25) at 0.22Hz of DPR. There was a significant difference between VOR and OVR gains (P<0.01, t-test). COR was almost absent and was not measurable in 6 subjects of the 21. Six other subjects showed constant gain (mean 0.16, SD 0.06) over the course of DPR (frequency 0.33Hz). The remaining 9 subjects showed gain enhancement at later cycles (3rd to 5th cycles) of DPR. The mean COR gain of this group was 0.81 (SD 0.30). Cervically induced eye deviation occurred in an anticompensatory mode in most of the cases with the mean phase advancement of 82°(SD 33.6°). There was no significant correlation between VOR and COR gains in healthy human subjects.
Optokinetic nystagmus (OKN) and smooth pursuit eye movement were studied in fifteen patients with a brain tumor. In the patients with a cerebellar tumor, OKN was normal at lower stimulus velocities and substantially diminished at higher stimulus velocities, while in the patients with a brainstem tumor, it was almost completely abolished at all the stimulus velocities. In these patients, saccadic eye movement occurred instead of smooth pursuit eye movement during the eye tracking test. In one patient with a VIIIth nerve tumor localized within the porus acusticus internus, OKN was diminished at higher stimulus velocities and smooth pursuit eye movement was normal. It was concluded that a neuronal circuit in the brainstem was responsible for eliciting OKN at lower stimulus velocities, that the cerebellum provided a neuronal circuit for eliciting OKN at higher stimulus velocities and that peripheral vestibular nerve inputs produced OKN of human beings.
In stationary animals, which experience rotation of large-field visual pattern, secondary vestibular neurons respond in a direction-selective manner. The total destruction of the flocculus, which sends inhibitory outputs to second-order vestibular neurons, results in impairment of optokinetic nystagmus (OKN). The prevailing hypothesis, based on physiological evidence, claims the vestibulocerebellum to be an essential final link mediating the optokinetic response to the vestibular nuclei. The flocculus, on the other hand, receives visual signals through a climbing fiber pathway and also through a mossy fiber pathway. In the previous report, however, the inferior olive which is a source of the climbing fiber was unrelated to OKN and visual suppression (VS) of caloric nystagmus. The nucleus reticularis tegmenti pontis (NRT) has been suggested to be a likely candidate for prefloccular relay nucleus conveying visual signals for OKN and VS of caloric nystagmus. In the present experiment, major concerns were to elucidate whether the ponto-flocculo-vestibular tract is related to optokinetic responses. To achieve this goal, OKN was evaluated after producing NRT lesions or floccular ablation in 20 cats. After damage to the NRT on the right side, cats could follow optokinetic stimuli, but showed extreme velocity limitation, at lower stimulus velocities. This limitation was alleviated in 3 weeks. After making unilateral flocculectomy, OKN was normal at low surround velocity (<30°/S), but was extremely velocity-limited at higher speeds. This change, however, disappeared rapidly within a week. Based on these datas, we suspect that NRT may be a relay nucleus mediating the visual signals responsible for OKN not to the flocculus but to the vestibular nucleus.
Shift of the gravity center and magnitude of the body sway were measured under various conditions using a micro computer system which samples the points of the darvity center successively and calculates the mean value and standerd deviation thereof. Ten normal persons and a few vertiginous patients were analysed, which revealed the clinical utility of tihs system.
The effects of horizontal and vertical optokinetic stimulation on head movement in neuro-otologically normal adults were investigated by using an optokinetic stimulator of Jung type, a cephalograph and a minicomputer. The cephalograph consisted of a lightemitting diode (LED) on the helmet and an industrial television system to pursue the movement of LED on the horizontal plane, an X-Y recorder and a data recorder. Computer analyses were performed with an off-line system. The followilg results were obtained. When the speed of optokinetic stimulation was increased the locus traced by the head movement and the total length of the locus gradually increased up to 60 deg/sec and then decreased. There was a standard two-phasic course in the position of the head movement. The ratio of the antero-posterior component to the lateral component of the head movement was below the control value with horizontal optokinetic stimulation, while with vertical stimulation it was over the control, showing a striking peak at 60 deg/sec of optokinetic stimulation. Spectral frequencies of the head movement showed two types of change. Type I showed a frequency shift to a higher division within the range below 1 Hz during optokinetic stimulation, while Type II revealed a peak at 0.2 to 0.3 Hz with 30 to 90 deg/sec of stimulation. The difference between the two types was manifest in the calculated averaged divisional frequencies of below 1 Hz.
Seventeen patients with vestibular neuronitis were followed up for the period ranging from 5 months to 6 years. The results obtained at the time of the follow-up examination were as follows: 1) Only one patient had a complaint of benign paroxysmal positional vertigo (BPPV) with positional rotatory nystagmus. Eight patients (47.1%) complained of unsteadiness when rising rapidly or walking in the dark. Two patients had had BPPV with positioning rotatory nystagmus during the course of illness. 2) Twelve patients (70.1%) presented spontaneous and positional nystagmus which had no relationship with the duration of their illness. 3) Twelve patients (70.1%) showed no response to caloric stimulation, while three (17.6%) showed slight and two (11.8%) normal response. 4) In the galvanic body sway test (GBST), five patients who were ill less than 3 years showed abnormal thresholds. 5) Of the nine patients, whose disease periods were more than 3 years, six complained of no symptoms, five showed slight or normal response to caloric stimulation and all the nine presented norma thresholds of the GBST. These results suggest that complete compensation of the vestibular system and some recovery of the peripheral vestibular function may take more than 3 years after the first vertigo attack caused by vestibular neuronitis.
In order to evaluate the involvement of histamine in Meniere's disease and to select drugs for the prevention of reccurent attacks, positional nystagmus was examined before and after the injection of histamine by means of Frenzel's glasses or ENG. Prior to the test it was observed for ten minutes that no apparent change developed without injection in twenty-six patients suffering from vertigo. Intradermal injection of 0.02 ml of 0.01% histamine was given to patients and normal persons. A distinct appearance or increase of the positional nystagmus ten minutes after the injection was evaluated as apositive reaction. When these changes were slight, they were classified as having negative reactions in the same manner as those who showed no change or no nystagmus. In Ménière's disease with episodes of vertigo with tinnitus and/or fluctuating hearing loss, thirteen of the cases (24.1%) were classified as having positive reactions. Nine suspicious cases of Menière's disease, thirty vertiginous patients and nine normal persons demonstrated negative reactions without exception. The positive reaction was more frequently observed in those who have the following features : age above forty, positive allergic history, hyporeaction in the caloric test, hearing loss of more than 31 dB, recent episode of vertigo within a week, histamine-binding power of less than 512 times of dilution, relatively high level of serum IgE and positional nystagmus to the affected side before the test. The reaction to histamine was often different at different trials, but nystagmus tended to appear to the affected side. These results suggest that histamine occasionally increases the excitability of the affected labyrinth in Meniere's disease.
We had surveyed school children living in two geographically remote areas with past and present histories of habitual motion sickness, which was reported in our precedingpaper. The present paper compares these results with those of a similar survey conducted 20 years ago (1961) by Hasegawa et al. and made an attempt to shed light on epidemiologic differences between the two surveys. The results are summarized as below. (1) The number of children surveyed who had history of motion sickness was 6, 875 in the 1980 survey and 872, 075 in the 1961 survey. (2) The peak age of the occurrence of motion sickness was 12 in the 1961 survey but 10 in the 1980 survey. (3) Asthma and tonsillitis, the chronic diseases harbored by children with habitual motion sickness, were fond to have increased in the intervening 20years. (4) The traffic vehicle that has caused the children to suffer from increased incidence of motion sickness most was automobiles. (5) The proportion of the children who complaind of nausea and/or vomiting in the 1980 survey was greater than in the 1961 survey. The proportion of the children complaining of fatigability while in cruising vehicles, as well as that of those who were frightened of automobiles, have also increased in the 20 years.
A 38-year-old woman with Ménière's disease and primary open angle glaucoma was reported. In this case, the vertigo attacks were always accompanied by glaucoma attacks and/or intraocular hypertension. Dehydration tests, i. e., the glycerol test and the furosemide test were positive, and after the tests, the intraocular hypertension was alleviated. The patient has been well controlled by acetazolamide.
Unit discharges of the reticular neurons and EMGs of extensors and flexors were recorded in the four limbs of thalamic cats during stepping on a motor driven treadmill to study the functional role of the spino-bulbo-spinal (SBS) reflex in locomotion. Reticulospinal (RS) neurons showed increased spikes from the end of the stance to the beginnning of swing phase; in this period, flexor muscle EMGs were obtained. To analyze the relationship between the activity in RS neurons and that in flexor muscles, RS neuron spikes were used for triggering and post-spike were averaged. Averaged EMGs of the correlated EMGs flexor revealed 12 and 6 msec latencies for hind and fore-limbs, respectively. Most RS neurons elicited EMGs of flexor muscles of ipsilateral one leg, some elicited flexor EMGs of both the ipsilateral fore and hindlimbs, and a few had diagonal innervations of flexors in fore and hind-limbs. The input and relay neurons of the reticular formation underlying the SBS reflex also showed alternative firing patterns during stepping. The relationship among the activities of the 3 groups of reticular neurons was analyzed by the postor pre-spike averaging techniques and appropriate latency response were obtained. The results indicate that flexor EMGs were excited reflexly in cats stepping on the treadmill. The role of the SBS reflex in locomotion is discussed.
Human upright standing can be regarded as a single reversed pendulum, which Supprts a mass of about 60 kg on a fine prop of one meter in height. In this heavy mass are included some oscillatory generators such as respiration, heart beats, muscle activities, etc. Especially, the leg muscle activities play the most important role for body sway. Body sway must be within an extremely limited area, or be controlled to stay in a limited area by some regulators. Under the latter condition a sensory system must exist in order to detect fluctuations of the body. This paper aims at examining the role of sensory information for postural adjustment. With a gravi-coder we analysed the body sway responding to perturbation of sensory information such as vibratory stimuli to the leg muscles, cold stimulation to a labyrinth and pursuit tracking movement by displacement of the center cf gravity.
Though human erect standing posture is very unstable, constant incline of the body due to gravity, etc., will always be restored holding a dynamic equillibrium ("homeostasis") of the posture to exhibit only invisible sway. Hence, the sway can be regarded as the response of the "posture control (holding) system" in the body elicited by various stimulations (gravity, ect.). Random time series of an appropriately magnified sway was able to describe as a higher-order autoregressive (AR-) process given as a dynamic extension of the basic static "stimulation-system (activity)-response" relation of a bio-system in the body. The AR-power spectral density of the postural sway, therefore, elucidated an average frequency-pattern of the higher-order posture control activity, which was decomposed into one or two first- and some secondorder component activities. One of the former exhibited more than 90% power displaying a damped exponential average time-pattern and a peak at OHz in its power spectrum, while each of the latter did less than about 5% power displaying a damped oscillatory average time-pattern with a damping frequency and a peak at the respective resonance frequency in its spectrum. In addition to the power, the smoothness and/or regularity of the posture controlv activity was given as the "bio-informing activity amount". Applying bivariate AR-processes to the anteroposterior sways of the center of gravity, head and sway of the dorsi-plantar flexion of the ankle joint, the "interactive control activities" between two of them were elucidated, which displayed also the average time-and frequency-patterns as the "impulse" and "frequency responses", respectively. No first-order component responses, but only the second-order ones were observed in the interactive posture control activities.