Effects of streptomycin on the otolithic organs were studied in guinea pigs by means of the scanning electron microscope. The most severe damage was found in the otoconia on the otolithic membrane. The layer of the otoconia on the otolithic membrane became thinner at the striola region. The longer the duration of streptomycin injection the fewer were the tiny otoconia evident in the otolithic membrane, and large otoconia remained on this membrane. The small otoconia were found on vestibular dark cells. The otoconia on the vestibular dark cells were irregular, shrunken or fragmented. Their calcium content, measured with an X-ray micro-analyzer, was diminished in varying degrees. The vestibular dark cells are considered to have pinocytotic activity. The surface structure of the endolymphatic sac was also observed. According to our morphological findings, three portions were recognized, the proximal, intermediate (rugous) and distal parts. Morphological changes of endolymphatic sac cells were no ed in the intermediate portion.
To analyze the correlation between change in the activity of a rabbit's hippocampus and eye movements induced by repeated electric stimulation of the brain, agents such as a cholinergic agent (carbachol) and an adrenergic agent (adrenaline), were injected into the hippocampus through a thin steel tube which had been inserted when the rabbit was under Pentobarbital anaesthesia. The injections were given before and after 10 electric stimulations of a rabbit's hippocampus, and resulting changes in the activity of the brain and ocular reflex were measured using the EEG's and ENG. Electrical stimulus used herein was 1msec., 200Hz pulse waves at 3 volts for 30 seconds. This amount of stimulus was given once a day for ten days. The following results were obtained; (1) The hippocampus produced two types of nystagmus in response to the agents mentioned above. One was a nystagmus which appeared shortly after injection of a cholinergic agent into a normal rabbit's hippocampus. Such was horizontal and directed to the side of the injection. The other was a nystagmus which appeared with a fairly long latency and was directed to the right and left. Such mainly appeared in an animal given repeated electric stimulation of the hippocampus when an adrenergic agent was given. However, on injection of a cholinergic agent into a normal rabbit's hippocampus, such also appeared in parallel with a rebound in the EEG's. Both types of nystagmus appeared on the basis of an arousal state in the EEG's. However, the latter type of nystagmus was always preceeded by marked seizure discharges covering the hippocampus, mid-brain reticular formation and neocortex. (2) As a result of repeated electric stimulation of a rabbit's hippocampus, it was found that excitability of the hippocampus in response to a cholinergic agent decreased, while that in response to an adrenergic agent increased.
The conduction velocity and other physiological characteristics of the first order horizontal canal afferents were studied in 24 anesthetized cats. From their spontaneous firing patterns, neurons were classified into three groups : regular, intermediate and irregular. The irregular neurons tended to have a low resting rate, high sensitivity to angular acceleration, frequently exhibited adaptation during prolonged acceleration, and showed a short latency from the time of electric stimulation of the labyrinth to recording the action potential near Scarpa's ganglion. The regular units tended to have a high resting rate, low sensitivity, were mostly non-adapting, and showed a longer latency to electric stimulation. The intermediate neurons had a mixed character of regular and irregular units. Since the latency is due predominantly to conduction in the first order axon, and since there is a direct linear relation between conduction velocity and fiber diameter in the medullated nerve fibers, it is possible to speculate that the regular cells have thin fibers which innervate the slope of the crista, the irregular neurons have thick fibers which innervate the summit of the crista, and the intermediate units have medium caliber fibers which innervate both the slope and summit of the crista ampullaris.
Long-term observations on equilibrium disturbances in patients with unilateral and bilateral loss of labyrinthine excitability were undertaken. The purpose of the study was to elucidate the peculiarity of equilibrium disturbances when the compensatory adjustments are inefficient and clarify how the labyrinthine reflexes function in the daily behavior of humans. The study included 6 patients with unilateral loss of labyrinthine excitability and 5 with bilateral loss of labyrinthine excitability. Questioning and equilibrium related examinations were performed at regular intervals for periods of more than 5 years after the incidence of the loss of labyrinthine excitability. Equilibrium disturbances continuing more than 5 years were as follows : (1) Those with unilateral loss of labyrinthine excitability On questioning, the patients complained of disturbances of body balance in standing and walking in the dark. On the standing test, the patients could not maintain Mann's and one-leg standing. Writing and stepping deviation were not remarkable. Spontaneous nystagmus under the Frenzel's glasses continued. The optokinetic nystagmus was normal. (2) Those with bilateral loss of labyrinthine excitability On questioning, the patients complained of disturbances in visual fixation while walking and running (jumbling phenomenon) and disturbances of standing and walking in the dark. The standing test with eyes open was within normal limits but that with eyes closed indicated moderate to marked disturbances of righting function. Staggering gait was observed in the stepping test. The optokinetic nystagmus was normal, showing visual fixation when the stationary position was not disturbed. The results indicate that the vestibulo-ocular reflexes in humans play an active part in visual fixation during movements with periodic head motion such as walking and running and that the most important role of the vestibulo-spinal reflexes is the righting reflexes which aid in maintaining standing posture.
Fluctuating hearing loss is a characteristic feature of Meniere's disease, but in some cases, hearing deteriorates gradually and progresses to an irreversible state after repeated fluctuation. In other cases, hearing loss develops rapidly and to a moderate degree. Ninety-two cases of unilateral Meniere's disease according to the criteria of the Research Committee of Meniere's Disease of the Japanese Welfare Ministry were studied. Among them the progression of hearing loss of twenty-nine cases was evaluated, and three or more audiograms were obtained during the observation period of at least six months. Hearing loss was classified into four categories-progression, fluctuation, progression with fluctuation and unchanged. Progression was said to occur if the hearing level changed over two frequencies between 250Hz-4000Hz by 15dB increase and remained at this state for at least six months. Fluctuation in hearing was said to occur if the hearing level changed over two frequencies by at least 15dB and again returned to the original level. Progression with fluctuation. was said to occur if the hearing showed the conditions of both progression and fluctuation as mentioned above. Unchanged : No change during the observation period. The results were as follows : 1) Hearing fluctuation was seen in most cases within three months. 2) Progression of hearing loss was observed in 34% of twenty-nine cases, while fluctuation of hearing was seen in 41%. 3) Hearing loss within one year after an initial vertiginous attack varied in degree, while the hearing loss was progressive with time. 4) Progression with or without fluctuation can be judged within three years, according to the criteria mentioned above. 5) Electrocochleographic studies using a trans-tympanic recording demonstrated positive summating potential (+SP) at 8000Hz in most cases. No changes of +SP were, however, observed after either endolymphatic sac operation or furosemide injection (20mg). Based on these findings mechanisms of hearing progression, the relationship of +SP to Meniere's disease and therapeutic effects of endolymphatic sac surgery as a preventive method for hearing deterioration or progression were discussed.
Vogt-Koyanagi-Harada's syndrome is exudative iridocyclitis and choroiditis associated with temporary or permanent loss of hearing and visual acuity, graying of hair, and depigmentation of the skin. Seven patients with this disease were encountered at the Neurotological Clinic of Yamaguchi University Hospital from July 1975 to June 1977. The neurotological results were tabulated. One representative case is reported herein and a review of the literature and discussion are made from the neurotological standpoint.
Neuro-otological examination was evaluated from X-ray films in eleven cases of temporal bone fracture. Fracture lines on the X-ray film are not always visible in a case of head trauma. Several X-rays and tomography should be obtained. Fracture lines on the films were identified in five cases, in whom there was similar nystagmus in cases of “so-called vertigo of benign paroxysmal positional type.” This pathological nystagmus can be detected by positional and positioning tests. In X-ray examinations, both Sonnenkalb's and Stenvers' view were evaluated.
Two cases of neurinoma of the IX, X, and XIth cranial nerve are reported. Case 1 : 48 year old male Symptoms of the VII, IX, X, and XIIth cranial nerve were evident. The tumor was observed at the hypotympanum and was confirmed to be a neurinoma as diagnosed by biopsy. Case 2; 31 year old female The symptoms of the V, IX, X, XI, XIIth cranial nerve were evident. In both cases, the dilatation of the jugular foramen and the destruction of the pyramidal apex were seen. Obstruction of internal jugular vein was confirmed by retrograde-jugulanography. The symptoms of involvement of the VIIIth cranial nerve and brain stem were somewhat more apparent than in the case of the acoustic tumor.
Various approaches such as pneumoencephaloroulette tomography, scintiscanning, CT scanning, cisternal myelography are available for radiological examination of lesions of the posterior cranial fossa, and in some cases, these examinations are partinent for a neurotological diagnosis. We evaluated radio-logical findings in 25 patients with the cerebellopontine angle lesion and the results are as follows : In some cases without clear findings in Stenvers' projection nor detectable nystagmus, CT scanning was useful. For differential diagnosis of a non-serious cerebellopontine angle lesion such as cystic arachnitis, pneumoencephalo-roulette tomography proved to be useful. The cisternal myelography was not evaluated herein.
Pathological findings in equilibrium tests were compared with neurological tests in 27 patients with brain tumor, who visited our neuro-otological clinic. Appearance rate of abnormal findings in neuro-otological tests was higher than in neurological examination. Pathological findings obtained by neuro-otological tests, must be followed up by further neurological examinations except for special findings which have high diagnostic value, such as, convergence nystagmus, gaze palsy, MLF syndrome, etc. To determine the site, size and pathology of brain tumor, all results obtained by neuro-otological, neuro-logical, radiological examination and other findings in laboratory tests should be evaluated.
Basilar impression can be diagnosed according to the measurement of the height of the axial process seen on the X-ray. Down beat nystagmus is considered to be a characteristic finding in basilar impression, however, such is not apparent in all cases. In our 4 cases, the relationship between the existence of down beat nystagmus and the height of the axial process had no apparent relationship.
The tegmentum of the midbrain in particular the pretectal area has been considered responsible for upbeat nystagmus. Recently, however, Gilman et al. (1977) reported a 54 year old male who showed spontaneous upbeat nystagmus. Autopsy revealed infiltration of astrocytoma into rather an extensive area of the brainstem mainly in the Inferior Olivary Nucleus. We performed experiments in which the Inferior Olivary Nucleus was destroyed in cats and observed the upbeat nystagmus. However, the following autopsy showed that the area of destruction was localized not only at the Inferior Olivary Nucleus, but also at the Paramedian Reticular Nucleus, Hypoglossal Nucleus and Pyramidal Tract. However, no lesions were observed at the Vestibular Nuclei or upper brain stem. Clinically we experienced a case, 22 year old female, showing spontaneous upbeat nystagmus with forward gaze or eyes closed and central nervous lesions were suspected after a series of equilibrium tests, BSR, etc. We consider that the area of lower brain stem or the floor of the IV ventricle, midbrain tegmentum including cerebellar vermis in the vertical pursuit system play role in the occurrence of spontaneous upbeat nystagmus.
A patient with ataxia, ophthalmoplegia and areflexia, suspected to be a typical case of Fisher syndrome or Parinaud syndrome was examined at the Yamaguchi University Hospital. This paper is presented from the neurotological standpoint of view. A 72 year old female had a tinnitus, hearing impairment and “heavy head” sensation for two years. In the two months prior to the first visit, double vision and gait disturbance developed following a sudden rise in blood pressure (from ususal blood pressure, 140/60mmHg, to 200mmHg). Upward gaze paralysis and mild speech disturbance developed, and remained. Body posture on sitting was normal. Righting reflex tests : poor and unstable, i.e., not able to stand upright even in the Romberg test. Writing tests (Fukuda's test and Sekitani's Square Drawing Test) revealed ataxia with tremor, and marked macrographism and deviation to the left side. Optokinetic test (OKP) : poor elicitation with questionable inversion. Eye tracking test (ETT, horizontal and vertical) was saccadic in character. CT scan : within normal in the figure. Lumbar puncture and CSF study : within normal range. She was treated with steroids, vitamins and a vasodilator drug for a short period. Clinical course was favorable with fair recovery of ataxia and areflexia, and also a reduction in “heavy head”, but the upward gaze paralysis remained for a year and a half. Localization of the lesion was considered to be around the pretectal area of the midbrain; bilateral, although more involvement on the right side with a lesion in the tegmentum.
A 46-year old man with congenital nystagmus had an alternate nystagmus after a traffic accident. Nystagmus has a common developing mechanism. The occurrence of pathologic conditions involving oculomotor regulatory mechanisms of the cerebellum and the involvement of the communicating tracts in and around the cerebellum can be presumed. Congenital nystagmus, head injury, vascular disorders and infections should all be considered when making a diagnosis of nystagmus alternans.
Of the central nervous disorders observed neurotologically from 1975-77, 41 cases-midbrain diseases, pontine tumors, cerebella-pontine angle tumors, acoustic neurinomas, cerebellar diseases and IV venticular tumors-were topographically diagnosed, and we investigated the influence on the oculomotor system and localization of the lesions. In case of midbrain diseases, abnormality of vertical OKN was noted in all cases, indicating the definite difference from abnormality of horizontal OKN. Marked disturbance by gaze nystagmus test, OKN and ETT in particular severe disturbed horizontal eye movement were observed in cases of pontine tumors. The cerebellopontine angle tumors and acoustic neurinomas showed 60 to 80% abnormality in all tests. Many cases of cerebellar diseases indicated saccadic pursuit pattern on the eye tracking test. Hereafter, by means of computer analysis of experimental nystagmus test as well as further detailed observation of basic nystagmus responses, neurotological findings together with usefulness of CT-scan on topographical diagnosis may enhance the possibility of early diagnosis and topical diagnosis.
Visual suppression is one method of demonstrating the function of visual fixation. Visual suppression is calculated by measuring the slow phase velocity of caloric nystagmus with eyes covered in darkness and that with eyes open, fixed in light. Visual suppression was 54±12% in 52 normal adults. Clinical cases of typical and localized lesions in the cerebellum or brain stem were selected and tested. Visual suppression of caloric nystagmus towards the lesion side was reduced or abolished in cases of cerebellar (especially flocculus or nodulus) lesions. Visual suppression of caloric nystagmus towards both sides was reduced or abolished in cases of diffuse or bilateral cerebellar lesions. Visual suppression of caloric nystagmus towards the lesioned side was strongly abolished and even augmentation of caloric nystagmus in light with eyes fixed was seen in cases of brain stem (especially pontine) lesions. Thus, with this visual suppression test it can be determined whether the lesions are in the cerebellum or in the brain stem.
The data obtained in patients with vertigo and equilibrium disorders following β-adrenergic stimulant (dl-isoproterenol hydrochloride) and Co-enzyme Q (Ubiquinone) administration indicated that vertiginous attacks in these patients probably were the results of enhancement of the β-sympathetic system. The regional action of β-sympathetic system in β-adrenergic stimulant administration was more likely to appear with changes in excitability of the unilateral vestibular organ (in Meniere's disease) other than static dysfunction (in sensorineural hearing loss and equilibrium disorders) and effectively provided relief for the symptoms of Meniere's disease. Attacks of vertigo did follow in some patients. On the other hand, the uniform mass discharge in the sympathetic system was likely to appear in cases of β-adrenergic stimulant administration to patients with bilateral positive findings in The Mild Caloric Eye Tracking Pattern and Repeated Mild Caloric Eye tracking Pattern Tests. The results (the superimposed phenomena) in these tests revealted indications of β-adrenergic stimulant and Co-enzyme Q administration to patients with vertigo and equilibrium disorders.
A method for computer analysis of the skipping eye tracking test was developed as a functional test of saccadic eye movement. The saccadic visual stimuli were applied by seven small lamps horizontally placed at the same interval with eight degrees of visual amplitude and turned on in a stepwise jump manner with the period of 0.04, 0.06 and 0.1Hz. Recording eye movement was made with DC or AC (time constant with 3.0sec) and was stored on magnetic tape (TEAC R-410). In normal subjects, DC-ENG recordings of eye movements following the stepwise skipping visual stimuli showed regularly stepwise saccadic patterns corresponding with the visual stimuli. However, pathological patterns of the stepwise saccadic eye movements showed irregular and/or delayed patterns. These pathological patterns have been interpreted by visual intuitive reading from the ENG recordings in the conventional way. Therefore, to evaluate the patterns of saccadic eye movements quantitatively, we measured the amplitude, duration, and velocity of saccadic eye movements, and the period during fixation at the luminous lamp. The normal limits of these measurements calculated from six normal subjects were statistically evaluated by means of a small general purpose digital computer (PDP 11/40). Thus, it can be seen from our measurements that the normal variations of saccadic eye movements obtained from our skipping eye tracking tests have a tendency to decrease with the shorter period of the stepwise skipping target movements. After these normal observations, we would like to recommend that the skipping eye tracking test with a period of 0.1Hz is most appropriate for clinical observations. Moreover, from our normal observations, we reconfirmed certain predictive control of saccadic eye movements in our saccadic eye movement tests, which was applied in the same amplitude, stepwise manner, with the same interval of saccadic jump.
When a human subject follows a moving object with his eyes, two different types of movement are noted : smooth pursuit movements and rapid, jerky changes of position known as saccades. Smooth pursuit movements enable the fovea to be maintained on a continuously moving object, whereas saccades serve to bring the fovea promptly on to an eccentric point in the visual field. Eye tracking test (ETT) for investigation of smooth pursuit movements is nowadays one of routine tests in neurotological or neuro-ophthalmological clinics and various apparatuses have been used. However, as patients have to sit in front of them during the test, most serious patients in the neuro-surgical ward cannot be examined before surgery. For this reason one of the authors (Y. Chiba) designed a new handy apparatus for ETT at the bedside, and Mr. Shyosuke Matsuoka (Director of Mochizuki Electric Co. Ltd.) developed it as shown in Figures 1 and 2. The apparatus has 64 light targets using L.E.D. As the light targets line up straight and a red light is turned on and off, one by one, the red target seems to move smoothly and continuosly on a line back and forth due to residual light. The procured records are as accurate as those obtained with apparatus in neurotological clinics, and clinical experiences demonstrated several merits : 1) As it is small and portable, it can be easily used either at the bedside or in an outpatient clinic. 2) It can be used at the bedside even in patients who cannot be easily transported because of severe increased intracranial pressure or marked vertigo. 3) Even infants can follow a red target with interest, because the target moves back and forth automatically. 4) Vertical smooth pursuit movements can also be easily examined by turning the apparatus 90°. 5) Patients can also be examined while in a sitting position when the grip part of the apparatus is connected with the attached stand. 6) The price is reasonable.
To clarify the correlations among the swaying movements of the human body, the cross-power, the coherence and the phase were calculated by means of a computer. Five normal subjects were examined. The subject stood on a gravicorder with his feet close together. Head movement was picked up by means of a two channel accelerometer attached to a helmet on the head. Two dimensional sways of the body's center of gravity and head, anteroposterior and lateral movements were registrated on a magnetic tape. The data were transmitted to a computer in the form of digital values after A/D transformation. Auto-powers of arbitrarily chosen two movements were calculated with fast fourier transform of these two time series. Cross-powers, coherence and phase angle of these two movements could be produced from these two auto-powers. These results were displayed on a CRT. There was no remarkable difference in the cross-powers of any two movements, sways of body's center of gravity and head accelerations, in any direction, antero-posterior and lateral. On the contrary, the coherence and phase showed a remarkable contrast between the different combinations of moving directions. In the same direction, coherence between sways of body's center of gravity and head acceleration showed a high value and the phase difference was slight. Between different directions, coherence between any combination of sway of body's center of gravity and head acceleration showed a low value and the phase difference was large. Therefore, coherence and phase are much more important than crosspower when discussing the relationships between any two movements. There is only a weak correlation between movements of any portion of the body in different directions, while on the contrary, movements of different portions of the body in the same direction show strong correlations.
The present study deals with the pathognomonic signs found in the spectral patterns of the body's center of gravity during standing. The static sensonograph using the strain gauge technique, was used to obtain, from a subject standing normally on the platform, a continuous record of the movement in the horizontal plane. The data was at the same time supplied to a data recorder, which separately stored this data of lateral and antero-posterior movement on the tape. The recorded data on the tape was fed into a digital computer for the spectral analysis, by means of the Fourier technique. The experiments were conducted on 102 vertiginous or ataxic patients. Each subject was placed on the platform of the sensonograph with feet together and asked to face straight ahead. Recordings were made with the eyes both open and closed. Each set of recordings was repeated three times in order to verify the reliability of the examination. Six basic pat erns of the frequency spectra were obtained. 1) Peripheral vestibular lesion The frequency spectrum in the closed eye trial showed a peak or amplitude augmentation at 0.2 to 0.3Hz. 2) Spinal lesion The frequency pattern with eyes closed closely resembled that with the eyes open except for the higher peaks in the closed eye test. 3) Cerebellar lesion The frequency spectra were of wide range extending to above 2Hz with several high peaks in the antero-posterior component and one in the lateral component. 4) Cerebral lesion The basic potential in the movement of the center of gravity was relatively high throughout the spectra (below 3Hz). 5) Parkinsonism Very low frequency spectra were recorded. 6) Proprioceptive hyperactivity There was a characteristic pattern of frequency spectra showing 2.0 to 2.5Hz peak in the lateral and/or antero-posterior component.
Visual suppression on body sway during standing on a foam rubber mat was investigated in 82 normal subjects, 44 patients with peripheral vestibular disorders and 42 patients with cerebellar or brain stem lesion. As a result, visual suppression score on static posture in patients with cerebellar or brain stem lesion was lower than the score in both normal subjects and patients with peripheral vestibular disorders. The significance of the difference at the 0.01 level was confirmed statistically. Visual suppression on static posture is an available test in clinical differential diagnostic procedures to distinguish between peripheral and central vestibular disorders.
Effects of pathologies in the internal auditory meatus on the auditory-evoked brain stem response (BSR) were assessed in two patients with tumors. In a patient with the facial neurimona, wave I of the BSR was recorded, alone. In a patient with acoustic neurinoma, the intervals between wave I latency and wave V latency were markedly delayed compared to those of the normal. In order to clarify the interpretation of the results, the effects of middle and inner ear pathologies on the BSR were assessed in four patients with conductive and sensory hearing losses. In these patients the disappearance of the waveform of the BSR was not observed and the intervals between wave I latency and wave V latency fell within the normal range. The data were interpreted as showing that the disappearance of certain BSR components, especially those following wave II, as well as an increase in the difference between wave I and wave V latencies can be used as indices of pathology of the internal auditory meatus.