Embryonic development of human vestibules and semicircular canals was morphologically studied with scanning and transmission electron microscopes. The inner ears of six fetuses, from 9 to 23 weeks of age, were obtained for the study with permission of their families. Otoconial crystals were observed in a 9-week and 2-day old fetus, which had slightly rounded facets in both ends. Anterior and lateral semicircular canals seemed to be equally developed at 11 weeks and 2 days of age. The bundles of sensory cilia were densely distributed on the crista but shorter in length than those of the matured inner ear. Remarkably short, underdeveloped bundles of sensory cilia were also found on the crista. Transmission electron microscopic observation reve-aled that type I and type IT sensory cells were differentiable not in the 12-week and 5-day old and 14-week and 6-day old fetuses but in the fetuses older than 20 weeks and 3 days of age. Contacts of afferent nerve endings to sensory cell and synaptic ribbons or bars were also observed in the same 20-week and 3 -day fetus. Between 20 weeks to 23 weeks of fetal age, the surfaces of the macula and the vestibular dark cells appeared mature in morphology.
Horseradish peroxidase (HRP) was injected iontophoretically into the caudal part of the dorsal nucleus of the raphe (DNR) in cats. Labeled neurons with HRP were recognized in the medial and the superior vestibular nuclei. Furthermore, those were also recognized in the magnocelluar division of the alaminal spinal trigeminal nucleus. Electrical stimulation of these nuclei elicited orthodromic evoked potentials in the caudal part of DNR which were characterized by a negative potential occurring at a peak latency of 1-1.5 msec. Furthermore, electrical stimulation of these nuclei elicited unitary responses in the caudal part of DNR. It failed to occur at stimulus frequencies above 30 Hz and its atency fluctuated at each stimulus. These findings in the present study strongly suggest that there exist afferent projections from these nuclei to the caudal part of DNR.
Electrical stimulation of the mesodiencephalon in 32 conscious rabbits was performed with the aim of elucidating its oculomotor function in the present experiments. For each animal a bipolar stimulating electrode was permanently implanted into one of the following structures : area pretectalis (Prt), nucleus pretectalis anterior (PA), nucleus lateralis posterior thalami (LP) nucleus ventralis basalis thalami (VB), tractus opticus (OT), nucleus medialis dorsalis thalami (MD), nucleus reticularis tegmenti (Tg), nucleus pretectalis (PR T) and lamina medullaris posterior thalami (Lmpth). Saccades were induced from these sites except for OT, some parts of PA or part of LP and central nystagmus was induced from OT, PA and LP. The most favourable stimulation condition for inducing saccades was a train of rectangular pulses of 0.5 msec in duration at a frequency of 400 Hz and that for the central nystagmus a train of rectangular pulses of 0.5 msec in duration at 50-100 Hz. Saccades occurred in the direction generally ipsilateral to the stimulation sites and were horizontal, oblique and vertical depending on stimulation sites. Threshold intensities ranged from 0.25V to 8V (av. 3 2V) and latencies for the oculomotor effects from 75 msec to 190 msec (av. 124 msec). There was a tendency that the threshold became progressively lower with deeper placement of the electrode at PA. Although patters of the induced saccades were greatly influenced by changing eye positions via the otolith reflex, there was no indication for the so-called goal directed eye movements. In contrast, the threshold for the induced nystagmus was lowest at OT with the slow phase ipsilateral to the stimulation site. To clarify the neural pathway responsible for the central nystagmus, ablation of the flocculus and paraflocculus contralateral to the stimulation site was carried out but no consist-ent result was obtained. It seems that the flocculus is not involved in the main pathway for the central nystagmus. But the fact that the nystagmus was facilitated in darkness and with an eye blindfolded ipsilateral to the stimulation site suggests that the flocculus may be relevant to the nystagmus to some degree.
Recent physiological data have suggested that it is very likely that the pretecto-ponto-vestibular pathway mediates optokinetic (OK) responses. In the previous report, based on these physiological data, the nucleus reticularis tegmenti pontis (NRT) was unilaterally injured electrically in order to clarify the role of NRT on the generation of OK responses in cats. The cats with damaged NRT could follow OK stimuli but showed extreme velocity limitation from lower stimulus velocities. This limitaiton, however, was alleviated in 3 weeks in all NRT-lesioned cats. In the present experiment, NRT were bilaterally injured in order to ascertain whether NRT were bilaterally concerned with unilateral generation of OK responses. The bilateral NRT lesions were histologically evaluated in 6 cats. In 2 of the 6 cats, OK responses were impaired in both directions and the OK impairment persisted. In the remaining 4 cats, OK responses were impaired in both directions only at early stages. These limitation, however, recovered rapidly in either direction during the subsequent follow-up period, and resulted in the unilateral impairment of OK responses. When lesions were histologically asymetrical, i. e., lesions were large on one side as compared with the other, the imparment of OK responses tended to be alleviated in time. The present data suggest that bilateral NRT may be concerned with the unilateral generation of OK responses.
By divising a method to record arm-deviation during the test of perrotary or optokinetic nystagmus, the relation between arm deviation and nystagmus was investigated. For this purpose the following procedure was performed. The subject was asked to sit on an electrically driven turning chair and repeatedly swung the "knob" horizontally with a constant amplitude and frequency. Handling of the knob, which was set on the turning chair, was done with the right arm slightly extended in front of the subject. Movement of this knob could be recorded electrically as serial sine curves. This graph was named "arm-kine-tograph". The center line of arm-kinetograph, by which arm-deviation could be detected, was traced by a "signal processor 7TO7A". Change of amplitude and frequancy in arm-kinetogragh could be analysed by the same computer. Rotatory stimulation was used for this investigation as follows.: The subject with eyes securely blindfolded sat on the turning chair with the head bent forward 30 degrees. The chair was rotated with the trapezoidal method. Stimulation of±2, 4, 6 and 8°/sec2 were used for every 10 seconds. The chair was first rotated clockwise and then contraclockwise. In order to eliminate the influence of the previous turning, the subjects rested for 4 minuits between measurements. During this rotation test, parotatory nystagmus, arm-deviation and velocity of the turning chair were recorded at the same time. In application of optokinetic stimulation, the drum, which had black and white stripes incide it, was rotated around the subject with triangular method of±4°/sec2. During this test, optokinetic nystagmus (OKN), arm-deviation and rotation velocity of the drum were recorded at the same time. The arm-kinetograph of 34 normal subjects were investigated and the following results were obtained: 1) Arm-kinetograph in non-stimulated conditions At the beginning of recording, the center line of arm-kinetograph fluctuated irregularly. But after short training, it became stable. 2) Change in arm-kinetograph of normal subjects induced by rotatory stimulation After the stability of the center line in the arm-kinetograph was obtained, rotatory stimulation was applied. The incidence of arm-deviation and the magnitude of the maximum arm-deviation increased in accordance with the strength of rotatory stimulation. The subjects with dominant arm-deviation had a tendency to show large amplitudes of perrotatory ny-stagmus. Most of maximum arm-deviation appeared after the occurrence of the nystagmus which had the maximum eye-speed of the slow phase. It was interesting that the direction of arm deviation induced by weaker stimuli (2, 4°/sec2) mostly corresponded with the quick phase of perrotatory nystagmus, while that of stronger stimuli (6, 8°/sec2) had a tendency to be directed to the slow phase of nystagmus. On the other hand, amplitude and frequency in the arm-kinetograph of normal subjects were not influenc ed by rotatory stimulation, while the dysmetric and arrhythmic change of the arm-kinetograph of those with cerebellar disease were manjfested by application of rotatory stimulation. 3) Changes in the arm-kinetograph of normal subjects induced by optokinetic stimulation. Arm-deviation induced by optokinetic stimulation had a tendency to be directed to the quick phase of OKN at slow speeds of the drum, but the direction was changed to the opposite side at high speeds of the drum. In most cases the maximum arm-deviation appeared after the occurrence of the nystagmus which had the maximum eye speed of the slow phase. The amplitude and frequency of the normal arm-kinetograph were not influenced by optokinetic stimulation, while the dysmetric and arrhythmic changes of those with of cerebellar disease were manifested by the same stimulation.
The cerebellum is known to be very important for the maintenance of body balance or of smooth eye movements. Eye movements consist of two factors, that is saccade and pursuit, which are examined using the stimuli of saw-toothed waves. A round target of 1 cm in diameter moves from the right to the left side with a visual angle of 30° for the period of 3 sec and it moves back to the right side immediately after the target has reached to the left side. This reversed stimulus is also used. The saccade and pursuit eye movements were evoked in the examinees who followed the traget movements, which were recorded by an electronystagmography (ENG). The eye velocity of saccade and the latency between the initiation of the target and that of eye movements were measured. Horizontal eye movements, saccade and pursuit were studied. The numbers of small saccadic eye movements during the pursuit eye movements were measured. In 20 normal adults, the eye velocity of saccade was 169±19°/sec, the latency 0.15 ±0.05 sec and the small saccadic eye movements 0-1 beats/cycle during the pursuit eye movements. In 27 cerebellar lesions, the eye velocity of saccade was within normal limits, the latency prolonged and the pursuit eye movements strongly impaired. That is, the pursuit eye movements seem to be closely related with the cerebellum.
It is the desire of the neuro-otlogic clinician to record routinely the nystagmus of patients with vestibular disorders, but it is troublesome to have it done frequently. We tried to have patients record their own nystagmus themselves using a portable electrocardiograph. It is sixty-five millimeters wide, twentyeight millimeters thick, one hundred fifty millimeters long and three hundred grams in weight. It can be operated easily at any time and any place by laymen and often provides beneficial information. When we performed the caloric test on nine patients, we recorded the nystagmus with an ordinary electronystagm ograph and with this equipment simultaneously. It has been recognized that the records with a portable electrocardiograph bore close resembrance to the records obtained with an ordinary electronystagmograph. A twenty-six-year-old lady who was diagnosed as having vestibular neuronitis was shown to have prosperity and decay of the positional nystagmus during the course of recovery. Another record revealed that a sixty-one-year-old lady had positional nystagmus only upon rising in the morning. Moreover, this equipment is useful for conducting examinations in remote places, because it is portable. We think that daily recording of nystagmus will be helpful in evaluating the efficacy of drugs and recommending changes in the mode of living for some patients.
The normal standing posture was evaluated by means of the Fourier analysis of the movement of the center of gravity in 20 normal subjects standing erect. Power spectra of the movement of the center of gravity were transformed to root values. Percentages of the summed root values in each freguency range against the total value were compared in several standing postures. The results obtained in this study are as follows: 1. In Romberg's posture, the value in the frequency range less than 0.5 Hz was about 50% in the left-right (X) direction and about 55% in the anteriorposterior (Y) direction both with eyes open and with eyes closed. Decreases in the value in the ranges from 4 to 5 Hz and from 5 to 10 Hz in the "X" direction and increases in the value in the ranges from 0.5 to 1 Hz and from 1 to 2 Hz and decreases in the value in the ranges from 4 to 5 Hz and from 5 to 10 Hz in the "Y" direction under the condition of eyes closed in comparison with eyes open were statistically confirmed. 2. The values in the frequency range from 2 to 3 Hz increased and in the range from 5 to 10 Hz decreased in the "X" direction and the values in the range less than 0.5 Hz decreased and the values in the ranges from 0.5 to 1 Hz, 1 to 2 Hz, 2 to 3 Hz, and 3 to 4 Hz increased in the "Y" direction when the subject was asked to change his standing of Romberg's posture to Mann's posture with his eyes open. However, the difference between the values in Romberg's posture and in one foot standing in both "X" and "Y" directions was the same as the difference between the value in Romberg's posture and in Mann's posture in the "Y" direction. No difference was obtained between standing on one foot on the left leg and on the right.
The temporal relation between the date of vertiginous attacks of Meniere's disease and the so-called Kritische Tage in the biological rhythm was observed in 57 attacks of 19 patients who had no other somatic conditions which would induce same attacks. Three rhythms, namely physical (P), sensitivity (S) and intellectual (I) which fluctuate with different cycles of 23, 28 and 33 days, respectively were considered. Most of Meniere's attacks tended to appear just on the Kritische Tage or on days before or after it, and the tendency was significantly stronger in the P-rhythm than in the others. Furthermore, it was demonstrated that the attacks of six patients out of the subjects always had arisen on the same day of the same cycle, that of four patients arisen on closely the same day of the same cycle and that of another four arisen on the same day of the different cycles. These must be considered in clinical practice for the prevention and the management of succeeding attacks of Meniere's disease.
Patients with Meniere's disease as well as two control groups (non-Meniere peripheral vertigo and chronic otitis media) were tested with a Japanese version of the Maudsley Personality Inventory (MPI). Patients with Meniere's disease showed significantly lower L (lying) scores of the MPI than each control group, and higher E (extraversion-introversion) scores than with chronic otitis media. There was no significant difference of N (neuroticism) scores between patients with Meniere's disease and each control group. The scores of each group were compared with reported data on normal Japanese adults. Patients with Meniere's disease had significantly lower L scores and those with chronic otitis media had significantly lower E scores than normal Japanese adults. The tendency of low L scores of patients with Meniere's disease was found to have no significant relation to the patients' age, degree of hearing loss or duration of the disease.
It is a well-known fact that many inner ear disorders, as represented by Meniere's disease, have their onset with initiatory symptoms of rotatory vertigo, tinnitus and hearing loss. Because of the important role of these three symptoms in the diagnosis of inner ear diseases, their presence tends to prompt the otologist to seek the causative lesion in the periphery of the inner ear. We recently encountered two cases in which the onset of disease featured tinnitus and hearing loss in both ears, vertigo and 'jumbling'(symptoms suggestive of Meniere's disease). Low density areas were noted on CT-scanning These suggested a diagnosis of bilateral cerebellar infarction. Emphasis is placed on the likelihood that diseases involving the basilar artery or the superior cerebellar artery begin with tinnitus, hearing loss and vertigo.
ENG examination were performed in 1, 457 patients in the past six years at Tokai University Hospital. Remarkable directional preponderance (DP) was occa-sionally found on the damped pendular rotation test of Greiner (épreuve rotatoire pendulaire), especially in patients with vestibular neuronitis and herpes zoster oticus with vertigo. Strong DP on the damped pendular rotation test was confirmed in the patients whose threshold of nystagmic response to counter-DP side was above 12°/sec2 of maximum acceleration in this study. In those examined within thirty six days after the onset of vertigo strong DP was found when viral infection such as the following were implicated: seven of the 15 patients with vestibular neuronitis (46.7%), four of the nine patients with herpes zoster oticus with vertigo (44.4%), one of the three patients with labyrinthine disorder due to mumps (33.3%), three of the 34 patients with sudden deafness with vertigo (8.8%) but none of the 22 patients with sudden deafness without vertigo. Patients with strong DP had remarkable positional nystagmus in ENG but never showed signs of disorder indicative of the central vestibular system involvement on the optokinetic nystagmus pattern test. eye tracking test or damped pendular rotation test, Most of them presented unilateral canal paresis on the caloric test. From the survey of histopathological findings of these diseases in the literature strong DP in the damped pendular rotation test suggests viral infection of the vestibular nerve.
This paper was intended to examine whether the power spectral density of the body sway in upright standing was always stable or not. We used 8 healthy subjects, who were asked to stand on a force-plate with their eyes open or closed. One trial length was 3 minutes, and 5 trials carried out had intermissions of 5 minutes between each trial. Each trial was stored in a magnetic tape and fed into a computer in the form of digital values through an A/D converter. The sampling interval was 60 msec, so that the datum of each trial was transformed to 3, 072 digital values. One block was constructed 1, 024 digital values. Eight blocks extracted from one trial of 3, 072 points were obtained by moving their start adresses in 256 points steps, from 1 to 1, 793. Each block of 1, 024 points was transformed to the power spectrum by means of an F F T method, which was imposed 4 times of the Hanning window for smoothing. In this way, 8 power spectra were obtained from one trial and were named P1 to P8 in order of adress. The density of the power spectrum was expressed by logarithmic values. A standard deviation calculated from 10 power spectra (P3 and P7 in each trial) of each subject was less than log104 in all the frequency ranges computed, and also was not affected by two visual conditions, viz. eye open or closed. In order to investigate the time dependent variety, 8 power spectra from P1 to P8 were compared with the mean of 5 power spectra (P3 in each trial) in all the frequency ranges They were named power-ratio-spectrum. The power-ratio-spectra were found to have values between 1/4 and 4 in either case of the anterior-posterior or the right-left sway. Our results suggested on account of our analysis time and data length that there were no large varia-tions in the successive analysis
Forty cases of benign paroxysmal positional vertigo (BPPV) were reported. The most predominat age of the patients was the fourth decade, followed by the third and fifth decases. There were very few patients younger than 30. Ninty percent of the BPPV patients noted their critical position themselves, which is useful for the diagnosis of BPPV. Spontanous nystagmus was not seen in any of the patients. Characteristic nystagmus was seen in positional nystagmus and/or positioning nystagmus under the critical position. Vertigo and nystagmus disappeared in 62 Oo of the cases within 4 weeks and 26% within 1 - 2 months, in 12 % vertigo persisted more than 2 months and they presented unilateral reduced caloric responses relatively often. One of them was treated by physiotherapy with precipitating head positions on a repeated and serial basis. The characteristic nystagmus of BPPV was sometimes found in patients suffering from sudden deafness, Meniere's disease, head injuries and so on. We supposed that the pathogenesis of BPPV might be concerned with not only otoliths but also semicircular canals.
Transient eye deviation on head rotation was electronystamographically observed during the examination of positional nystagmus with eyes closed. In 98.8% of the 1419 electronystacmograms, transient eye deviations were of same direction as that of the head rotation. In 0.6%, those deviations were observed only on head rotation to one direction, in 0.4% were not recognized on head rotation to either direction and in 0.2 of showed to be to the opposite direction to that of head rotation due to the vestibuloocular reflex-Most of latter three groups were those with conjugate gaze palsy, abducens palsy, congenital blindness, or lesions in the paraportine reticular formation. Based on these findings, it is suspected that this transient deviation of the closed eyes on head rotation is similar to the saccadic movement of lateral gaze that was discussed in the eye-head coordination by Bizi et al (1972). In other words, after the system of lateral gaze is completed in the central nervous system, this saccadic eye movement may be elicited without visual input by head rotation alone.
Aiming at the investigation of the smooth pursuit ability of the human eye toward the target movement, we developed a new sinusoidal target wave and analysed the results quantitatively. The target wave we developed consisted of 20 continuous sinusoidal waves which lasted from 0.1 Hz to 2.0 Hz. The frequency increased at the peak of each wave so that target moved smoothly. The amplitude was 10 degrees (20 degrees in total amplitude). This target wave was made with a microcomputer (CBM 8032) by BASIC and ASSEMBLER, and was transferred to the target projection instrument (KN 52 Nagashima) via an 8 bit D/A converter. In this report we performed this examination in the horizontal direction. The eye movements which were stimulated by this target wave were analysed with a mini-computer (PDP 11/34) and three parameters were obtained quantitatively. The first parameter (velocity ratio) was the ratio between the maximum eye velocity and the mean eye velocity. The second parameter (phase difference) was obtained by the calculation of time difference between the target wave and the eye movement at 4 points (peak, bottom and two belleys) for each sinusoidal wave. The third parameter (amplitude difference) was calculated by the subtraction of total amplitude of the eye movement from total amplitude of target wave (20 degress). These three parameters were obtained for each 20 sinusoidal waves and the average and 95, 05 confidential range were calculated and dispalyed on CRT of PDP 11/34. Three parameters were included between the 95% confidential range on the patients with peripheral lesions. The patients with central lesions showed abnormalities in three parameters. One case with alcoholic cerebellar atrophy demonstrated abnormal findings on this examination even though routine equilibrium examinations had detected no abnormalities.
Benign brain tumors, especially meningioma, do not produce any objective clinical finding. Most patients show no abnormality even on pneumoencephalography or angiography. Consequently, meningioma has been difficult to diagnose. CT-scanning, however, is capable of detecting meningioma, which cannot be diagnosed by routine outpatient examinations. It is no exaggeration to say that CT-scanners made the diagnosis of meningioma possible. Recently we have examined eight cases of meningioma using the CT-scanner and correlated chief complaints and findings from routine outpatient examinations which are attributed to meningioma. We have established the following criteria on the diagnosis of meningioma: 1) The most outstanding complaints are transitory, repetitive or spontaneous oscillopsia and vertigo of short duration. 2) While a vertiginous attack is slight and short in duration, nausea and headaches are severe and long-lasting. The discrepancy between the two should be noted. 3) The symptoms may be remitted or repetitive. There is no symptom during the intermittent period. 4) Vertical or rotatory nystagmus appears on the record of ENG with the eyes closed. 5) There are some symptoms indicating disorders of the central nervous system. 6) There is a falling tendency on the sagittal plane.
Eight patients with Fisher's syndrome of 8 to 65 years of age were examined. The diagnosis of Fisher's syndrome was made by the classical triad which consisted of ophthalmoplegia, ataxia and areflexia. The purpose of this study was to clarify whether the lesion of Fisher's syndrome exist in the CNS or peripheral nerves. We have analyzed these patients by neurological examination: Bell's phenomenon was well preserved in half of our patients despite their upward gaze Palsy. Divergence palsy was detected in 4 of the 8. External ophthalmoplegia healed symmetrically in all of the eight patients. These phenomena were not explained in terms of peripheral lesions only On electrophysiological examination, normal peripheral nerve conduction velocities and normal EMG patterns were observed. In contrast, the Guillain-Barré syndrome was known to have remarkably delayed nerve conduction velocity because of the demylination of peripheral nerves. On an electronystagmographical study, ocular dysmetria, paralytic nystagmus, convergence palsy and convergence nystagmus were observed in the present series. It is emphasized that rebound nystagmus was detected in 5 of the patients. Rebound nystagmus was originally reported by Hood, which is considered to be caused by lesions of the cerebellum. We have concluded, therefore, that the lesion of Fisher's syndrome is in the CNS rather than in peripheral nerves.
In an attempt to investigate the neural mechanisms of acute ataxia in human Wernicke's disease, acute thiamine deficiency encephalopathy was produced in the rat by feeding them with a thiamine deficient diet in conjunction with daily subcutaneous injection of pyrithiamine, a thiamine antagonist. Between days 11-13, all of the rats fed on this regimen developed acute ataxic syndrome. It was classified into four stages according to the severity of the ataxia. The rats in stage one exhibited tremulousness of the head and body, restlessness and occasional ventral flexion posture. Stage two was manifest by widebased frank ataxic gait ; stage three, by inability to walk, although they could still right themselves on the floor. Stage four was manifest by inability to right themselves and with ventral flexion posture. ENG analyses of the vestibulo-ocular nystagmus, provoked by the pendular rotation of the head, revealed suppression of nystagmus as early as in stage one. During stage 2-3, marked suppression of the vestibular nystagmus was evident. However, following intraperitoneal injection of thiamine, the nystagmus reappeared within a few hours. The compensatory horizontal head movements were disinhibited during stages 2-3 and abolished totally in stage 4. Also, anti-compenstatory head movements were observed, although the movement was quite slow. This was thought to be a postrotatory behavior and perhaps not a true anti-compenstatory movements. The labyrinthine righting was impaired during stage 2 and totally abolished in stage 3. The pathological correlations of these observations were attempted by examining histological specimens of CNS in these animals. The impairment of vestibular nystagmus was attributable to the symmetrical lesions of the medial, superior, and less markedly the lateral vestibular nuclei and pontine reticular formation. Uninhibited compensatory head movements were perhaps due to the lesions of the pontine reticular formation, whereas the descending vestibular nucleus exhibited no significant pathology. The ventral flexion posture was in some way related to impaired otolith input at the level of the vestibular nuclei and/or medial reticular formation. The ataxic syndrome in experimental Wernicke's encephalopathy appears to correlate well with the human syndrome in which the global confusional state, ocular motor disturbance and ataxia are the cardinal manifestations. We speculate that involvements of the vestibular nuclear complex and the medial pontine reticular formation in Wernicke's disease would play major roles in producing oculomotor as well as ataxic parts of the symptomatology. The animal model of human Wernicke's disease shown here would be useful not only in investigating the causes of deficiency encephalopathy, but also in evaluating the functions of the vestibular portion of the brainstem in performing locomotions and vestibulo-ocular integrations.