The three-dimensional ultrastructure of the ciliary interconnections of the human vestibular end organs was investigated by scanning electron microscopy. Ciliary interconnections were observed between the neighboring cilia, which were tightly interconnected. These interconnections ran horizontally parallel to the cuticular plate. The tip links stretched from the tips of the shorter stereocilia to their taller neighbors. These links were arranged in the same direction towards the kinocilium. These findings indicate that the tip links may be involved in the sensory cell mechanical transduction system and that the horizontal interconnections may keep the cilia arranged in a bundle.

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Eye movements associated with eye closure (so called Bell's phenomenon) were studied in nine healthy adults with a scleral search coil technique. Two types of eye closure were tested : prolonged eye closure and natural voluntary blinks.
In eight of the nine subjects, upward, abductional and extorsional eye movements were observed during prolonged eye closure. In six subjects, similar eye movements were recorded during voluntary blinking. Only one subject showed upward, adductional and intorsional eye movements with blinking and prolonged closure.

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Cochlear blood flow was measured with a Laser Doppler flowmeter. The methods and the dose infused were as described in Chapter 2. Recordings from the basal turn of 6 guinea pigs in each group were examined in a study of the effects of hyperosmolar solutions of glycerol, mannitol, and urea. Recordings were made for 10 minutes beforre infusion and for 10 minutes after glycerol, mannitol, or urea infusion. Cochlear blood flow increased significantly after the infusion of glycerol. In contrast, in 6 guinea pigs there was no significant increase of cochlear blood flow after infusion of the same volume of physiological saline. Cochlear blood flow increased significantly after the infusion of mannitol, but not after the infusion of urea. A personal computer (NEC PC-9801) and soft ware made by ourselves were used to analyze these data. These results do not agree with those obtained by the H₂ clearance method.

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We have reduced noise markedly during ENG recording of the horizontal aspect of eye movement by placing the electrode on the eyebrow, not above the eyebrow.
Although the noise of frontal muscle electromyography was increased by placing the electrode above the eyebrow, it was decreased markedly by placing it on the eyebrow.
Although this procedure is not the one recommended by the Japan Society for Equilibrium Research, we propose it because it reduces noise markedly.

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Patients with unilateral vestibular deficits (31 with vestibular neuronitis : 39 with sudden deafness : 19 with Meniere's disease) were examined periodically for positional nystagmus and caloric nystagmus.
1) Vestibular neuronitis : On the first examination, positional nystagmus directed, to the healthy side was observed in all patients. Nystagmus disappeared gradually, but 20% had nystagmus even 1year after onset.
Caloric CP was observed in 76% of the patients who were examined at the time of the first attack, and in 100% of those examined within a week after onset. Caloric CP recovered almost in parallel with the disappearance of positional nystagmus.
2) Sudden deafness : Positional nystagmus disappeared gradually with a tendency to change direction in some cases. In the early period, positional nystagmus in most cases was directed to the healthy side, and that nystagmus disappeared earlier than did the nystagmus of vestibular neuronitis.
Caloric CP was observed in 8% of the patients with sudden deafness.
3) Meniere's disease : The direction of positional nystagmus changed irregularly and did not disappear with time.
None of the 17 patients with Meniere's disease showed caloric CP.

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A 62-year-old female presented with vertigo, tinnitus, sensation of fullness and fluctuating hearing loss of sensorineural type on the left ear. Thirteen years after, the vestibular symptoms disappeared naturally, but the cochlear symptoms are still present. Dehydration therapy, such as the oral administration of iso-sorbid or the intra-venous injection of furosemide aggravated the cochlear symptoms while overhydration therapy improved them. The results of the dehydration and hydration tests evaluated by hearing level were opposite to those frequently observed in patients with endolymphatic hydrops.Therefore, we assume that occlusion of the reuniens duct or utriculo-endolymphatic valve and endolymphatic collapse in the cochlea were responsible for the characteristic course of the symptoms in our patient.

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Opsoclonus was analyzed in two patients with acute encephalitis in the initial, extreme and recovery stages and the ENG and VTR findings were compared.
In the initial stage ocular oscillation was mainly in the horizontal direction, with an amplitude of 5-30 degrees and a frequency of 7-8 Hz. It started suddenly several days after the patients developed fatigue and fever. A series of 1-10 beats of eye movements with some pause of various durations was repeated.Head rolling from side to side with a small amplitude was sometimes accompanied by eye oscillations. The patients had oscillopsia and an unsteady and staggering gait.
The extreme stage started a few days after the initial stage. There was typical opsoclonus, consisting of multidirected but mainly vertical or diagonal oscillations of the eyes. The amplitude was large and reached 80 degrees. The frequency varied from 3-9 Hz. There were almost no pauses. The patients were unable to sit up, and their heads trembled in the same direction as the eye movements. Myoclonic jerks and ataxia of the trunk and extremities were maximum.
In the recovery stage, the eye oscillations gradually decreased, and flutter-like oscillations (FLO) appeared. They were mainly horizontal, 5-20 degrees in amplitude, and their frequencies were 7-8 Hz. Pauses of various durations followed each series of 1-10 beats. The patients were able to stand and walk.
Opsoclonus was triggered in all three stages by visual fixation, intention to move the eyes, mental excitation and sound stimulation.

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Diphenylhydantoin (DPH) is known to cause symptoms of intoxication, such as acute cerebellar ataxia, involuntary movements, nystagmus, etc. when given continuously and in excess, although it is also known to be an excellent antiepileptic agent.
We report here a 14-year-old female with DPH intoxication and review the literature on this subject. Neuro-otological examination of this patient revealed reversible functional disturbances in the cerebellum and brain stem, including spontaneous nystagmus, cerebellar ataxia, abnormal findings in the optokinetic pattern test, eye tracking test, etc. These symptoms and test results rapidly improved with reduction of the blood level of DPH.
It is concluded that neuro-otological examination is extremely useful for the diagnosis of and for the evaluation of the therapy of this condition, and should be used in addition to the measurement of blood levels of DPH and/or the follow-up of the clinical symptoms.

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To clarify the peculiarities of gait disturbances in patients with labyrinthine, cerebellar and spinal disturbances, head movements and activity of the soleus muscles were studied during walking.
The upward-downward (U-D), right-left (R-L) and forward-backward (F-B) movements of the head and activities of both soleus muscles were recorded by a polygraph with the aid of a five-channel telemeter. Head movements were recorded with three accelerometers attached to a helmet that the subject wore. Muscle activities was recorded by EMG with surface electrodes. At the same time the subject's foot-floor contact sequence was measured with electric switches in the shoes. These gait data were recorded on a pen oscillograph.
1) In normal subjects, head movement recording revealed regular U-D movement and F-B inclination twice in each walking cycle and regular R-L inclination once in each walking cycle. Each soleus muscle was activated at the stance phase once in each walking cycle.
2) A patient with unilateral labyrinthine disorder had head movements with irregular rhythm and ampulitude. L-R inclination of the head was not related to foot contact. The soleus muscle activities increased in the swing phase and decreased in the stance phase.
3) A patient with bilateral loss of labyrinthine excitability had small, indistinct head movements with no relation to foot contact or foot raising. The record of the soleus muscle activities indicated plolongation of the active time and overlap of the activities of the two sides.
4) A patient with spino-cerebellar degeneration had very irregular, unequal head movements, especially excessive F-B head movement. The active time of the soleus muscles was prolonged.
5) A patient with left hemiparesis due to cervical myelopathy had small, irregular U-D and F-B head movements and large, sine wave like sway in R-Lhead movements. The soleus muscle activity of the left side in the stance phase was less than that of the right side. The record of the electric foot switch indicated that the subject often missed foot raising of her left leg.

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Eye movements are very important indexes for evaluating vestibular disorders or neurological diseases. Eye movements are composed of two factors, slow and quick movements.
The slow component of eye movements is evaluated by pursuit eye movements or by the slow phase of optokinetic nystagmus (OKN). When the slow component of eye movements is impaired, smooth pursuit is disturbed, so it is saccadic or ataxic. Also, the slow phase of optokinetic nystagmus is flat without increase of velocity as the OKN drum velocity increases with or without spiky movements.
Disturbances of the slow component of eye movements are the following two types :
1) The slow component of eye movements itself is disturbed.
Pursuit eye movements are seccadic or ataxic, and the slow phase of the optokinetic nystagmus pattern (OKP) is flat with spiky movements in the slow phase direction. This type is seen in patients with cerebellar lesions.
2) Both slow and quick components of eye movements are disturbed.
Pursuit eye movements are saccadic, and the slow phase of OKP is flat and without spiky movements. This type is seen in patients with pontine lesions.

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In this Paper we studied the clinical effects of long-term urea medication in patients with Meniere's disease. The subjects were 32 patients with Meniere's disease whose main symptoms were recurrent vertigo, deafness, tinnitus and aural pressuresensation.
Urea (1020 g) was given orally before breakfast twice a week at the start of the therapy, then once a week as the clinical symptoms stabilized.
The patients were followed for 12 months. In accordance with the 1972 criteria of the American Academy of Ophthalmology and Otolaryngology, 23% had class A, 61% class B, 6% class C, and 13% class D results.
Vertigo was well controlled in 90% of cases, but tinnitus persisted intermittently in many patients.
There was no appreciable side effects.

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Delayed endolymphatic hydrops (DEH) was proposed by Nadol (1975) and Schuknecht (1976) as a pathological diagnosis. Because of severe hearing loss, the presence of endolymphatic hydrops (EH) cannot be demonstrated by the glycerol test or electro-cochleography. This paper discusses a clinical method of examining EH in this disease. The authors' earlier study, reported in Acta Otolaryngol (Stockh) suppl. 435 (1987), showed that EH in Meniere's disease could be detected not only by audiometry but also by the trapezoid rotation test. The demonstration of ipsilateral labyrinthine preponderance (LPi) by this rotation test is a useful indicator of the development of EH. The authors performed this rotation test in seven patients who satisfied Schuknecht's criteria of DEH by careful history taking and audiometry, and LPi was detected in five of them, especially before the onset of vertigo. It was concluded that the detection of LPi by the trapezoid rotation test should be added to the tests used for the exact diagnosis of DEH.

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The directional preponderance (DP) of caloric nystagmus was examined in 33 patients with unilateral cerebral vascular lesions. Only lesions which included unilateral internal capsule were chosen by CT-scan. The maximum slow-phase velocity (SPV) was measured by the ENG recordings of caloric nystagmus with 44°C and 30°C stimulations with eyes open inthe dark. The patients then fixed their eyes on a light 50 cm away for 10 seconds at 60 seconds after the beginning of the irrigation with 30°C fluid. The maximum SPV before or after fixation was used as the value in the dark and the mean SPV during the 10 seconds of fixation as the value in the light.
The SPV could be measured in 33 patients. DP to the ipsilateral side of the lesion (ipsi-LS) was observed in 17 patients (55%) and DP to the contralateral side (contra-LS) in 14 (45%) with eyes open in the dark-not a significant difference. However, significant tonic eye deviation over 20 degrees to the slow-phase side was observed in 15 patients during nystagmus only to the ipsi-LS and in 2 patients during nystagmus to both sides in the dark.
The SPV of nystagmus to the ipsi-LS was significantly (p<0.01) higher than that to the contra-LS in the light.
Our results suggest that the tonic imbalance may be reversed because of the cortico-fugal tonic fibers to the vestibulo-ocular system, contralaterally in fixation and ipsilaterally in non-fixation, obstructed in unilateral internal capsule.

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“Audiokinetic nystagmus” has been described, but its origin is not certain yet. This paper discusses the response of patients with BPPV to audiokinetic Stimulation.
We selected BPPV patients to study the response to audiokinetic stimulation because audiokinetic Nystagmus has been recognized in many patients with BPPV, and the lesion in BPPV is believed to be in the peripheral vestibular organ. Audiokinetic nystagmus was noted in 20 of the 38 patients with BPPV examined. Thus, the origin of audiokinetic nystagmus may be in the peripheral vestibular system.

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