To obtain objective evidence of olfactory vertigo in humans, two series of experiments were carried out using rabbits. We found that in healthy animals there was little evidence of nystagmic responses when they were stimulated by inhalation of vapor of liquid, garlic odor. However, rabbits which had been given repeated electric stimulation on the unilateral amygdaloid nucleus and which had developed nystagmic responses tended to show an appearance and/or increase of nystagmic responses after being stimulated with the garlic odor mentioned above. In the former, there was little evidence of nystagmic responses after an intravenous administration of adrenaline. In the latter rabbits, however, there was a significant development and/or increase of nystagmic responses after the same procedure. With reference to known fiber connections in the central nervous system and the mode of action of adrenaline, we postulate that in humans, the amygdaloid complex, particularly the adrenaline sensitive components play a major role, in the production of olfactory vertigo.
As a causal condition of vertigenous attacks in Meniere's, the labile reaction of the autonomic nervous system has been considered to contribute a fundamental role. To assess the close correlation between the autonomic nerve and vestibular system, a new thermal test of the hand immersed in water at 20°C and 45°C was employed as an autonomic stimulus to the patients with atypical Meniere's disease. Spontaneous nystagmus was elicited in 40 to 70% of the patients during stimulation. Only 20% of the same group showed normal values in Schellong's test. These appears to be a complicated correlation between neural mechanisms and vegetative-somatoreactions.
To assess the advantage of identification of the endolymphatic sac during the operative procedure, we measured the size and localization of the endolymphatic sac in seven patients with Meniere's disease, during the epidural shunt operation (Kitahara). The measured points are as follows; (1) Sinus Posterior Canal Line, (2) Lateral Canal Line Isthmus, (3) Posterior Canal End Isthmus, (4) Posterior Canal Line Isthmus, (5) α; Angle from Posterior Canal Lane to Center of Sac, (6) Isthmus Inferior Edge of the Sac, (7) Isthmus Inferior Edge, (8) Inferior Edge Superior. From the values obtained, it appears easier to identify the endolymphatic sac from the Posterior Canal End than from the Lateral Canal Line.
A recording apparatus to determine head movement has been developed and a basic study was done to obtain normal values of head movement and to estimate the significance of head movement as a righting reflex. Twenty healthy adults were included in the present experiment. The cephalographic system consists of an industrial television which picks up the movement of a light emitting diode (LED) on the helmet which the standing subject is wearing and transmits the movements in terms of voltage to a preamplifier connected to a wave control unit and finally to an X-Y recorder. The information obtained can at the same time be fed into a data recorder, which separately stores the data on anteroposterior and lateral displacement on the magnetic tape. The recorded data on the tape were fed into a digital computer for further analysis. 1. The locus traced by LED closely resembled that of the center of gravity (CG) in the same subject. 2. The total length of the locus during 1 minute of standing was 36.8±8.0cm with the eyes open and 69.7±10.5cm with the eyes closed. Those figures were smaller than those of CG. 3. The anteroposterior component of the head movement was larger than the lateral component as compared with CG. 4. Time course of the position of LED was similar to that of CG during standing with the eyes open, while it was different from that of CG during standing with the eyes closed. 5. The frequency spectra of the head movement showed a dominantly slower frequency and the averaged divisional frequencies were 0.39±0.05Hz (lateral component) and 0.34±0.04Hz (anteroposterior component) with the eyes open and there were frequency shifts to faster frequency when the subject stood with his eyes closed. The above-mentioned results suggest that the head movement is controlled by CG movement and that CG works to keep the head steady and maintain the eyes in a normal position.
To determine the dynamic characteristics of the labyrinthine righting system, transfer function of the system was calculated by using shoulder movements and righting movements of the head which appear during the standing position. The results computed were displayed as frequency response (i.e., gain and phase diagrams). (1) In healthy subjects, frequency response of the system indicated an increase of gain with the increase in frequency of the body sway (i.e., derivative control action). (2) In cases of bilateral loss of labyrintine excitability, gain diagram was flat and values of gains were low. These patients showed disturbances in the righting movements to rapid body sway. (3) In those with a unilateral loss of labyrinthine excitability, frequency response was similar to that seen in healthy subjects who showed some irregularity in gain and phase diagrams. These findings indicate that the labyrinth indeed plays an important role in provocation of the righting movements to short and rapid body sway.
Visual function plays an important role in the mechanisms concerning control of equilibrium function in standing ability and movement of humans. The Romberg test, well known among the tests for detection of abnomalities of equilibrium function in neurological diseses, is the best available when attempting to compare the sway of body with eyes open and closed. The influence of human visual function on the maintenance of equilibrium and the control of body sway was assessed by recording of the body sway when the eyes were closed and open in both bright and dark fields with the subjects in a standing position. Twenty healthy adults with normal visual and equilibrium functions and six patients with jerking type nystagmus were selected and tested while standing at 30° in a fan-shape foot position. The body sways occurring during eyes open and closed in bright field as well as in dark field were recorded using a Gravicorder. It was found that the greatest increase in body sway occurred when the eyes were closed in a bright field in both groups of subjects. This was quite contrary to our expectations as closing the eyes in a dark field should produce the greatest increase of body sway. From this experiment, we conclude that the effect of light on the vision rod plays an important role in maintaining equilibrium and control of the body sway and that the tectobulbar tract is closely associated with the labyrinthine righting reflex.
The subject was allowed to sit on a swivel chair with nonpolarizing electrodes placed at the outer canthus of the eyes and on the forehead and with his head tilted 30° forward in order to study the nystagmus evoked by rotatory movements of the body, accelerated and decelerated at an equal rate. The velocity of the slow component of nystagmus was increased with an increase in the velocity of rotation of the chair, and decreased as the chair was decelerated after the maximum velocity was reached. The direction of nystagmus was reversed before the chair was stopped. A theoretical formula is available by which to calculate the π/Δ for the cupula from the magnitude and duration of accelereation and the time of reversion of the direction of nystagmus on the assumption that the endolymph system within the cupula represents a damped torsion pendulum. The π/Δ for the cupula at an acceleration of stimulus of 2°/sec2, 3°/sec2, 4°/sec2, 5°/sec2, 6°/sec2, 7°/sec2, 8°/sec2 and 9°/sec2 as calculated by using the formula was 19sec, 14sec, 23sec, 31sec, 32sec, 22.5sec and 22sec respectively. A π/Δ of 16sec was obtained when the duration of postrotatory nystagmus was employed as a basis of calculation. The value for π/Δ was found to vary with different magnitudes of acceleration, even in the same subject. thus, further studies are required to refine the theoretical formula and the method of stimulation.
Pure tone audiometry and caloric test were performed in sensorineural hearing-impaired children. The following results were obtained : 1. In about 92%, the etiology was not demonstrable. 2. Hearing losses of 58 children (81%) were severe. The mean hearing levels were more than 80dB. 3. Nineteen children had a canalis paresis in the pathological ear. These results were correlated with either severe or progressive hearing loss. On the other hand, they did not correlate with any type of audiogram, history of mumps, and motion sickness. 4. Air stimuli given to younger children produced poor responses, since their ear canals were actually too narrow to use the air caloric stimulator (Model NCA-100). 5. From the frequency-histograms of nystagmus, air stimuli of 10°C for 60sec. were less effective than water irrigations of 4°C for 30sec. These results are significant, because the response of younger children to air stimuli is less accurate than the response to water stimuli.
In an attempt to clarify the role of each portion of the peripheral retina in the formation of optokinetic nystagmus, doughnut shaped visual fields were created by means of a visual field separator which has already been described in “Vestibular Mechanisms in Health and Disease”. A variety of sizes of central scotoma and two widths of doughnut, 10 and 20°, were used. Five healthy persons were tested. The optokinetic stimulation which was used mainly was as follows : 12 black stripes in every 30° were projected and rotated with a constant velocity of 30/sec. The overlapping method was employed for evaluation of the induced optokinetic nystagmus. There was no remarkable difference between the optokinetic nystagmus induced by the doughnut shaped visual fields with central scotomas of 20° and 40°. When the central 60 was covered, the optokinetic nystagmus was hardly elicited. The width of the doughnut resulted in a slight difference in the elicitation of optokinetic nystagmus. Thus, the parafoveal retina within 30° is most important for the induction of optokinetic nystagmus. On the other hand, the peripheral retina beyond 30° had a weak influence on the formation of optokinetic nystagmus.
A 23 year old male, college student, who had spontaneous nystagmus since childhood began to experience a vertiginous and heavy head sensation after accidental head trauma (followed by 6 hours of unconsciousness, yet there were no notable objective residual signs in neurosurgical examination shortly after awakening from the unconscious state). Otoneurological examinations revealed : 1) a horizontal pendular nystagmus when he gazed forward 2) An elder brother has a similar spontaneous nystagmus. 3) Head shaking, like a nystagmic head movement. 4) Inversion phenomenon appeared dominantly on the right Optokinetic Pattern Test. 5) Alternate nystagmus, even when gazing forward. 6) No notable cessation or reduction of nystagmus beats when he closed his eyes or when his eyes were covered; and 7) Some reduction in visual acuity.
Arnold-Chiari malformation involves neurological disorders such as hydrocephlus, cerebellar dysfunctions, etc. We treated two patients who had chronic progressive gait disturbance, ataxia, continuous neck pains and spontaneous vertical nystagmus (down-beat nystagmus). The final diagnosis of Arnold-Chiari malformation was made following precise neurootological examination, including VAG and Myelography.