In 1972, Tokita et al reported that the hyperextended posture which appears after bilateral destruction of the labyrinth is due to increased antigravity muscular tonus, and they suggested that contralateral inhibition is greater than ipsilateral excitation in the vestibulospinal system. The author studied the anatomical basis of contralateral control of the vestibulospinal system in the cat. After the injection of HRP in the cervical, thoracic and lumbar spinal cord, labeled neurons were observed in the pontine and medullary reticular formation and vestibular nuclei. 1) The reticulospinal tract which originates in the nucleus reticularis magnocellularis descended almost entirely ipsilaterally along the whole spinal cord. The number of fibers descending ipsilaterally was 10 to 20 times that descending contralaterally. 2) The reticulospinal tract which originates in the nucleus reticularis gigantocellularis descended bilaterally along the whole spinal cord. The number of fibers descending ipsilaterally was twice that descend-ing contralaterally. 3) The reticulospinal tract which originates in the nucleus reticularis pontis caudalis descended bilaterally along the whole spinal cord. The number of fibers descending ipsilaterally was the same as that descending contralaterally. 4) The vestibulospinal tract which originates in the rostral portion of the descending vestibular nucleus and the medial vestibular nucleus descended bilaterally only to the cervical spinal cord. 5) The vestibulospinal tract which originates in the caudal portion of the descending vestibular nucleus and the medial vestibular nucleus descended bilaterally along the whole spinal cord. 6) The vestibulospinal tract which originates in the lateral vestibular nucleus descended entirely ipsilaterally along the whole spinal cord. The reticulospinal tract which originates in the nucleus reticularis gigantocellularis is important as a system which relays information from the labyrinth of one side to both ipsi- and contralateral sites along the whole spinal cord.
The labyrinthine reflex is influenced by changes of head position. To elucidate the anatomical pathway involved in this reflex, the author studied the afferent route by the retrograde WGA-HRP method in cats. After the injection of HRP into either the dorsal or the ventral Deiters nucleus, labeled neurons were investigated in the spinal cord, cerebellum, contralateral vestibular nucleus complex and brain stem nucleus. 1) When WGA-HRP was injected into the dorsal Deiters nucleus, labeled neurons in the spinal cord were found mainly extending from the cervical to the lumbosacral spinal cord. A number of labeled cells were located predominantly contralaterally in the cervical segments, while a small number of labeled cells were found ipsilaterally in the lumbosacral segments. In the case of the ventral Deiters nucleus, labeled neurons were found extending from the cervical to the upper thoracic cord. Localization of la-beled neurons in the spinal cord was limited mainly to Rexeds laminae VII, VIlI. 2) When WGA-HRP was injected into the dorsal Deiters nucleus, Purkinje cells were labeled in the cerebellar cortex. Most of them were restricted to the anterior lobe vermis ipsilaterally. In the case of the ventral Deiters nucleus, labeled neurons were found in the fastigi nucleus. Most of them were localized in the rostral region contralaterally. 3) When WGA-HRP was injected into the dorsal Deiters nucleus, no labeled neurons were found in the contralateral vestibular nucleus complex. In the case of the ventral Deiters nucleus, a few labeled neurons were found in the superior, medial, descending and ventral Deiters nucleus. 4) When WGA-HRP was injected into the dorsal Deiters nucleus, labeled neurons in the brain stem nucleus were found in the lateral reticular nucleus, the inferior olive nucleus and the external cuneate nucleus, while a small number of labeled cells in the lateral reticular nucleus and the external cuneate nucleus were ipsilateral only. Labeled cells in the inferior olive nucleus were present contralaterally. In the case of the ventral Deiters nucleus, labeled neurons were found in the nucleus reticularis gigantocellularis, although a few labeled cells ware present contralaterally. These results suggest that Deiters nucleus may be functionally divided into two parts, dorsal and ventral. In addition, afferents to Deiters nucleus are considered to be closely related to the control of posture.
Body sway in the upright standing posture of patients with equilibrium disturbances was examined by stabilometry. Routine and precision tests recommended by the Board of the Japan Society for Equilibrium Research were performed. I. Routine test results Body sway while standing was investigated in 88 patients by routine tests, which included forwardbackward diameter, left-right diameter, Romberg rado and pattern of sway.The 88 patients were classified into 5 groups: (1) 10 with bilateral loss of labyrinthine excitability; (2) 57 with unilateral loss of labyrinthine excitability; (3) 17 with cerebellar disturbances; (4) 3 with spinal disorders; (5) 1 with peripheral neuropathy. 1. In Group 1, forward-backward diameter, leftright diameter and/or Romberg ratio of sway was increased. The sway pattern was of the diffuse type in most. 2. In 29 patients in Group 2, forward-backward diameter, left-right diameter and/or Romberg ratio was increased, and left-right sway was observed. 3. Sixteen patients in Group 3 had a diffuse large sway pattern. 4. Group 4 patients had a large sway, forwardbackward or diffuse. IT. Precision test results Six patients with abnormal sway patterns that were specific for a given localization of the disease were examined by the precision test which included unit locus length, forward-backward and left-right diameter, area, ellipse, center of the sway, velocity, standard deviation, skewness and kurtosis of amplitude probability density distribution, vector of velocity and power spectrum. The diagnoses were bilateral loss of labyrinthine function of unknown origin, right sudden deafness with unilateral loss of labyrinthine excitability, arterio-venous malformation of the cerebellum, infarction of a cerebellar hemisphere, caisson disease and Charcot-Marie-Tooth disease. 1. In the patient with bilateral loss of labyrinthine function, the sway of the center of gravity showed a large forward/backward sway with a regular periodicity of about 0.6 Hz. 2. Body sway of the patient with sudden deaf-ness showed a large left-right sway with 0.08-0.2 Hz. 3. Body sway of the patient with arterio-venous malformation showed a large and diffuse sway with a regular periodicity of about 0.7 Hz. 4. Body sway of the patient with cerebellar infarction indicated a slight increase of the area and velocity of the sway. 5. In caisson disease, the unit locus length, diameter and velocity of the forward-backward sway was markedly increased. 6. In Charcot-Marie-Tooth disease, the area of the sway and the velocity of the forward-backward sway was increased.
Body sway was analyzed by autoregressive and feedback models in an attempt to clarify the mechanisms involved in posture regulation. Sway of the head, shoulder, hip, knee and foot during upright standing were recorded polygraphically and stored in a PDP-11 computer. The data were processed by a standard method and 5-dimensional autoregressive and feedback models in a specially designed program. The results were displayed on a cathode ray tube and teletype as determinant of noise correlation matrix, power spectrum, correlogram, transfer function, impulse response and relative power contribution. Forward-backward (FB) and leftright (LR) sways during upright standing were examined in normal subjects with eyes open and closed. 1. The results of the standard method had advantage of showing actual body sways, but the gain diagrams of the power spectrum were not smooth. They were very smooth with the 5-dimensional autoregressive and feedback models. Furthermore, since the influence of past sways and feedback from five parts of the body were taken into account in the autoregressive model and feedback model, respectively, the resulting data had additional implica-tions. There is a feedback mechanism in posture regulation. The feedback model is superior for analysis of body sway in the upright standing posture. 2. The results obtained from the 5-dimensional feedback model in normal subjects were: a) The determinant of noise correlation matrix was close to 1. It indicated that the system composed of sways of the head, shoulder, hip, knee and foot had good feedback. The composition of feed-back was better for FB sway than for LR sway. b) The power spectrum of the head, shoulder, hip and knee were high at 0.1-0.2Hz and decreased thereafter as the frequency range rose from 0.1 to 10 Hz. c) The correlogram with the eyes open revealed a Markov process, while the correlogram with the eyes closed indicated a periodic component of about 0.2 Hz. d) In the transfer function, sways of the head, shoulder, hip and knee with small amplitude were demonstrated as output. e) The impulse response converged immediately. Recovery of posture against external disturbances was satisfactory. f) The relative power contribution indicated that each part of the body was not appreciably influenced by other parts but showed its intrinsic sway in a high frequency range from 0.2 to 1 Hz.
Disturbances of standing posture regulation in patients with vestibular, cerebellar, spinal and peripheral disorders were studies by a time series analysis with a 5-dimension feedback model. Sways of the head, shoulder, hip, knee and foot during upright standing were recorded with a position sensor system and stored in a PDP-11 computer. With the use of a 5-dimension feedback model the stored data were processed by a specially designed program. 1) In a patient with bilateral loss of labyrinthine excitability and a forward-backward (F-B) sway in the statokinesigram, the determinant was 0.43 in F-B sway. The power spectrum and the correlograms indicated periodic components of about 0.4 Hz in F-B sway. The impulse responses to head movements converged with periodic sways against external disturbances. The transfer functions calculated with shoulder movement as input and head and knee movements as output indicated increases of the gain. The relative power contribution showed that the pro-portion of head movement increased during sway of the shoulder, hip and knee. 2) In a patient with unilateral loss of labyrinthine excitability and a right-left (R-L) sway, the power spectrum and the correlograms indicated periodic components of about 0.3 Hz in R-L sway. The relative power contribution showed that the proportion of shoulder movement increased during the sway of the head, hip and knee in low frequency. 3) In a patient with spino-cerebellar degenera tion and a diffuse, large sway, the determinant wa: 0.025 in F-B sway. The power spectrum and the correlograms indicated periodic components of about 0.3 Hz. The impulse responses were divergent The transfer functions indicated disorders of coordination. 4) In a patient with an infarction of a cerebellar hemisphere and a small R-L sway, the determinants were from 0.57 to 0.77. The power spectrum and the correlograms indicated poor periodicity. The impulse responses were slightly divergent. The transfer functions and relative power contribution were similar to those in normal subjects. 5) In a patient with Caisson disease and a large F-B sway, the determinant was 0.007 in F-B sway. The impulse responses were divergent. The transfer functions calculated with hip movement as input and head and knee movement as output indicated in-creases of the gain. 6) In a patient with Friedreich's ataxia and an enlarged sway with the eyes closed, the determinants were from 0.31 to 0.74. The power spectrum and the correlograms indicated no periodicity. The transfer functions were similar to those in normal subjects. The relative power contribution showed that the propotion of the hip movement increased during sway of the head and knee. 7) In a patient with Charcot-Marie-Tooth disease and an enlarged sway with the eyes closed, the determinants were from 0.73 to 0.95. The impulse responses were convergent. The transfer functions and the relative power contribution were similar to those in normal subjects.
To clarify the role of the visual, vestibular and proprioceptive reflexes on the regulation of the upright standing posture, postural responses of subjects standing upright on a tilting platform were observed. The subject stood on the platform, and then the platform was tilted pseudorandomly in the forwardbackward (FB) or left-right (LR) directions. Movements of the head, shoulders, hips, knee and of the platform and the activity of the soleus muscle were recorded polygraphically and stored in a PDP-11 computer. Movement of the head was calculated as angular movement and linear movement. Data processing was perfomed with a specially designed program. (1) Transfer function was calculated by the Goertzel method. (2) Determinants of noise correlation matrix, power spectrum, correlogram, transfer function and relative power contribution were calculated with a 3-dimensional feedback model. Six healthy male adults were examined. 1. Transfer function calculated by the Goertzel method The transfer function was calculated from the angle of inclination of the platform as input, and the angle of inclination of the head and the displacement of the head, shoulders, hips, knees and the activity of the soleus muscle as output. 1) The gain of the respective regions of the body decreased with the increase in frequency of both the FB and LIZ inclinations of the platform. The phase lags of the respective regions of the body increased with the increase in frequency of both the FB and LIZ inclinations of the platform. 2) The phase lag of the angle of the head inclination to that of the platform inclination was 126°-191°at 0.3 Hz and 275°-360° at 2 Hz in both the FB and LIZ inclinations of the platform. 3) In the FB inclination of the platform, the difference between the phase lag of one region and the phase lag of another was large. In the LIZ inclination of the platform, it was small. 4) In the FB inclination of the platform, the soleus muscle was active when the platform was tilted forward. In the LIZ inclination of the platform, the soleus muscle was active when the platform was tilted to the same side. 5) The visual input reduced the gain of the amplitude of movement of the respective regions of the body at 0.3 Hz in both the FB and LR inclinations of the platform. 2. Analysis with a feedback model 1) The determinant of the noise correlation matrix was close to 1 except when the linear movement of the head in the LR inclination was a component of the system. It shows that the system has good feedback. 2) In the transfer function, when angular movement of the head in the FB inclination was a component of the system, the soleus muscle was active when the head was tilted forward. In the LR inclination, the soleus muscle was active when the head was tilted to the same side. When linear movement of the head in the FB inclination was a component of the system, the soleus muscle was active when the position of the head was forward. In the LIZ inclination, the soleus muscle was active when the position of the head was on the same side. 3) In the relative power contribution, it was assumed that the role of the labyrinth on soleus muscle activity is larger during linear acceleration of the head than it is during inclination or angular acceleration of the head.
The role of static and kinetic visual information in the regulation of the upright standing position was studied in 7 healthy subjects. The subject stood on a stabilometer with the feet close together and gazed at the visual pattern (11 vertical stripes drawn at intervals of 4 cm). The postural sway under normal illumination, stroboscopic illumination at a frequency of 10 Hz, 5 Hz, and 1.4 Hz, and in darkness was recorded for 30 seconds with an X-Y recorder and stored in the disk of a microcomputer. On the basis of the stored data, concerning the area, unit locus length, forward-backward and right-left diameters, standard deviation, skewness and kurtosis of amplitude, the probability density distribution and power spectrum were calculated by a specially designed program. 1. The size of body sway under stroboscopic illumination at a frequency of 1.4 Hz was larger than in the dark. Examinations related to sway-area, for-ward-backward and right-left diameters, and standard deviation of amplitude probability density distribution showed similar results. 2. Kurtosis tended to be small under stroboscopic illumination at a frequency of 1.4 Hz. 3. The rate of low frequency (0.033-0.195 Hz) in the power spectra of body sway under stroboscopic illumination at a frequency of 1.4 Hz was larger than in the dark. Static visual information without kinetic visual information caused destabilization of posture regulation. Kinetic visual information plays a major role in visual control in the upright standing position, especially in the control of body sway at low frequency.
A method was devised for recording labyrinthine evoked electromyograms (EMG), and the nature of the vestibulospinal system was studied by this method. The subject was asked to stand with eyes closed on a stabilometer and was stimulated with a galvanic current. The vestibulospinal response induced by the stimulation was observed in terms of the sway of the body's center of gravity (stabilometry) and the activity of both soleus muscles. The muscle activities were recorded as integrated EMG with surface electrodes. The reactions induced by repetitive stimulation between 5 and 10 times were averaged with a microcomputer. 1. Cathodal stimulation by a monopolar-monoaural method induced ipsilateral excitation and contralateral inhibition of soleus muscle activity with a latency of about 100 msec and a duration of about 400 msec. The inhibitory effect was greater than the excitatory effect. This evoked EMG reflected a response through the otolithic system. 2. Monopolar-biaural stimulation by cathodes in both ears induced inhibition of both soleus muscle activities with a latency of about 135 msec. This result indicated that in vestibulospinal control, the inhibitory influence was stronger than the excitatory influence on the soleus muscles. In general, the role of the labyrinth in postural regulation has been explained as a facilitatory effect exerted by the lateral vestibulospinal tract on the extensor muscles. However, our observations clearly demonstrate that the inhibitory influence on the extensors predominated in the total labyrinthine system. 3. Direction of body sway and soleus muscle activity induced by galvanic stimulation with the head turned to the left were opposite to those with the head turn to the right even with the same labyrinthine stimulation. This result indicates that the vestibulospinal system produces spinal reflexes after processing information transmitted from the neck proprio-ceptors.
The peculiarities of gait disturbances of patients with labyrinthine disturbances were examined by a 3-step gait test. (1) Information on the characteristics of the gait disturbance was obtained in each examinee. (2) While walking 10 m with the eyes open and closed, the stability of the body, coordination of the head, trunk and extremities, step length, step width, and time required for walking 10 m were recorded. (3) Head movements in the vertical, rightleft and forward-backward directions were recorded by a pen oscillograph on a polygraph and also on a PDP-11 computer disc. The power spectrum and autocorrelation were calculated from the recordings. 1. Patients with unilateral labyrinthine disturbances complained of staggering toward the affected side when walking with eyes closed. In the 10m walking, step length was short, gait was slow and step width was broader than in normal subjects. During walking, the vertical head movement was less and the right-left sway more than in normal subjects. 2. Patients with bilateral loss of labyrinthine excitability complained of inability to control their legs and staggering. During the 10 m walk, shortness of step, tardiness of gait, and broadness of step width were marked. The right-left sway of the head during walking increased and the vertical movement decreased, and an irregular forward-backward sway of the head appeared, indicating a disturbance of linear progressive movement.
A pendular rotation test was carried out to investigate the dynamic characteristics of the vestibuloocular system. The purpose of. this study was as follows : (1) In normal subjects, to calculate the transfer function (TF) of the right and the left vestibulo-ocular systems. (2) In patients with a unilateral labyrinth, to calculate the TF of rightward and leftward eye movements separately, and to detect vestibular asymmetry. The subject was asked to sit a rotating chair. A sinusoidal pendular rotation was given to the subject with eyes open in the dark. Chair rotation was made as random as possible. The chair (head) and eye movements were recorded. The TF was calculated with head velocity as input and eye velocity as output. For the calculation autoregressive analysis was used. Prior to the calculation, saccadic eye movements were eliminated from the eye movements. In normal subjects, the eye velocity curve was divided into eye movements induced by the right labyrinth and those induced by the left labyrinth. In patients, the eye velocity curve was divided into rightward eye movement and leftward eye movements. The TF was calculated by using these eye movements as output. The results were displayed as Bode plots. In normal subjects, gain diagrams of the vestibuloocular system indicated frequency dependent gain enhancement from 0.01 to 2.2 Hz at the rate of 4.2 dB/decade. In the Bode plots of the right and the left vestibulo-ocular systems, the gain decreased to 5 dB at 0.1 Hz, compared with that of the vestibuloocular system. In patients, gain diagrams of the unilateral vesti-bule-ocular system were the same as the gain of the unilateral vestibulo-ocular system in normal subjects. Patients who were examined within a few months after the onset of disease, showed that the gain of eye movement toward the healthy labyrinth was low, in the frequency range from 0.01 to 0.1 Hz, compared to that in the opposite direction. In patients who were examined more than 3 months after onset, these differences of gain were not detected.
Voluntary and reflexive optokinetic nystagmus (Schau-and Stier-Nystagmus by Ter Braak) was examined in patients with cerebellar disorders. An Ohm type rotating cylinder was rotated electrically with an angular acceleration of 2°/s2 for 90s. Optokinetic nystagmus (OKN) was analyzed with a computer and specially designed program. In the qualitative test, stripe movements and nystagmus waves were displayed in superimposition on a cathode ray tube. From the relationship between the two, the ocular ability to catch and follow the stripes was evaluated. In the quantitative test, the number of nystagmus beats, average eye speed of slow and rapid phases and average amplitude for 10s were calculated. These values were compared with those of normal subjects. The tests were performed on 2 patients with lesions in the cerebellar hemisphere, 11 with lesions in the vermis and flocculus, and 7 with lesions in the cerebellum and brain stem. 1. No abnormalities were noted in voluntary and reflexive OKN, or the voluntary OKN was slightly impared in the patients with lesions in the cerebellar hemisphere. 2. In patients with lesions in the flocculus, voluntary OKN was decreased at high cylinder speed and reflexive OKN was decreased at all cylinder speeds, but there were no abnormalities of wave form. 3. In patients with lesions in the posterior vermis, voluntary OKN showed saccadic movements in stripe pursuit and ocular dysmetria for the target catch. No abnormalities were noted in reflexive OKN. 4. In patients with lesions in the cerebellum and brain stem, voluntary OKN showed irregular pursuit and was markedly decreased. Reflexive OKN showed disorders of wave form, or was markedly decreased.
Five patients with craniovertebral junction anomalies were examined neuro-otologically. Three patients had Chiari I malformation and cervicobasilar bone anomalies. Magnetic resonance imaging (MRI) showed cervicomedullary kinking, in addition to peg-like tonsils below the level of the foramen magnum (Group A). Two patients had Chiari I malformation without any cervicobasilar bone anomalies (Group B). We noted the differences in neuro-otological findings between the two groups and the changes after operation. 1. Differences in neuro-otological findings (1) Group A patients had downbeat nystagmus in the dark with the eyes open on forward and lateral gaze. Horizontal OKN abnormalities were as follows : at a stripe speed of 0-50°/s, pursuit of stripe movement showed stair-like swaying. When the stripe speed was increased further, pursuit of stripe movement became virtually impossible, and the number of nystagmus beats decreased markedly. (2) Group B patients had no nystagmus in the dark with the eyes open. Horizontal OKN abnormalities showed saccadic pursuit during stripe movement, and a decrease in the number of nystagmus beats at a high stripe speed (more than 100-110°/s). 2. Changes in neuro-otological findings (1) In group A, surgery improved the areas of sway in stabilometry tests, the frequency of nystagmus and the visual suppression rate of the slow phase velocity of caloric nystagmus. Horizontal OKN abnormalities were unchanged. (2) In group B, surgery improved the areas of sway, visual suppression rate and horizontal OKN. These results provide evidence that Chiari I malformations should be divided into those with and those without cervicomedullary kinking.
This study evaluates the effect of conservative treatment of Meniere's disease and the signs which can be used to predict the effectiveness of the treatment in 60 patients with Meniere's disease. Subjects are 60 Meniere's patients treated conservatively. 1) Treatment for vertiginous attacks. Effectiveness for treatment were evaluated by complaints of vertigo and spontaneous nystagmus. Sedatives were effective for aborting the attacks. 2) Treatment for inner ear dysfunction. Inner ear dysfunction was evaluated by hearing and equilibrium tests. Hearing tests showed an improvement rate of 38%. In equilibrium tests, improvement rate was 71% for the caloric test, 80% for the standing test, 63% for the writing test and 71% for the stepping test. 3) Treatment for recurrent attacks. Recurrent attacks of vertigo responded well to treatment in 18 of 26 patients (69 %) according to the criteria of the AAOO (American Academy of Ophthalmology and Otolaryngology, 1972) and in 12 of 20 patients (60%) according to the criteria of the AAO-HNS (American Academy of Otolaryngology Head and Neck Surgery, 1985). 4) Prediction of therapeutic effectiveness for recur-rent attacks. The effectiveness was analyzed by Hayashi's quantification method II. Good response and poor response groups could be differentiated clearly. a) The correlation ratio was 0.4180 (AAOO criteria) and 0.6219 (AAO-HNS criteria). b) The duration of the disease and the caloric CP were the principal items for discriminating between the two groups. c) The success rate for this discrimination was 77% (AAOO criteria) and 85% (AAO-HNS criteria).
Patients with disequilibrium due to peripheral vestibular disorders or to disorders of the central nervous system were trained. Subjects: 7 patients with unilateral vestibular disorder, 3 with bilateral vestibular dysfunction, and 7 with central nervous system disorders (6 with infarction of the capsula interna, and one with cerebellar infarction). The duration of the training was 1 to 8 months. Methods of training: 1) Eye and Head movements-first lying in bed, then sitting up in bed. 2) Standing-standing with feet close together, putting one foot in front of the other, and standing on one foot. 3) Stepping-stepping first with both hands holding on to a support, and then with both arms stretched forwards. 4) Walking-rising from a sitting to a standing position and walking straight, then turning round. 5) Revolving without support. 6) Going up and down stairs or a slope. These training procedures were performed three times a day. Evaluation of effects of training: Standing test, gait test and stabilometry were performed once every 2 months. Results: Equilibrium function was regained in all 7 patients with unilateral vestibular disorder, in 2 of the 3 with bilateral vestibular dysfunctions, in 2 of the 6 with capsula interna infarction, and in 1 patient with cerebellar infarction. Because some patients with vestibular disorder can regain equiliblium without training, the progress of the trained patients was compared with that of the untrained, This comparison indicated that (1) in the patients with unilateral vestibular disorders training had no definite advantage, (2) in the patients with bilateral vestibular dysfunctions equilibrium was regained faster by training and the patients with chronic vestibular disorders of 19 to 24 years duration also benefited from training.