Studies on vestibulo-spinal reflexes by examination of labyrinthine-evoked EMGs of lower limbs.

Evoked electromyograms (EMGs) induced by galvanic stimulation of the labyrinth were examined in the muscles of the lower limbs. The labyrinthine-evoked EMGs appeared in the muscles of the femoral and gluteal regions and of the legs, and these muscle activities were changed by the head position in spite of the labyrinthine stimulation being the same. The vestibulo-spinal reflexes fulfil these functions in coordination with the neck proprioceptor.

WGA-HRP studies on the fiber connections from the spinal cord to the Deiters' nucleus.

The labyrinthine-spinal reflexes are influenced by the inputs from the cervical and lumbal propriocepters. We studied the afferent route by the retrograde WGA-HRP method in cats. After the injection of WGA-HRP into either the dorsal or the ventral Deiters' nucleus, labeled neurons were investigated in the spinal cord, the cerebellum, the contralateral vestibular nucleus complex and the brain stem nucleus. In this paper, we report the results in the spinal cord of cats. i) 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 area of the spinal cord. A number of labeled cells were located predominantly in the contralateral cervical segments, while a small number of labeled cells was found ipsilaterally in the lumbosacral segments. ii) In the case of the ventral Deiters' nucleus, labeled neurons were found extending from the cervical to the upper thoracic area of the spinal cord. Localization of labeled neurons in the spinal cord was limited mainly to Rexed's laminae VII and VIII. These results suggest that the afferent fibers from the spinal cord to the Deiters' nucleus are closely related to the labyrinthine-spinal reflex.

Modulation by head and trunk positions of the vestibulo-spinal reflexes evoked by galvanic stimulation of the labyrinth. Observations by labyrinthine evoked EMG.

Modulation by head and trunk positions of the vestibulo-spinal reflexes was studied in the soleus muscle activities induced by galvanic stimulation of the labyrinth. The stimulation was applied using a bipolar-biaural method with the cathode on the right ear and the anode on the left ear. The intensity was 1 mA and duration 3 s. 1) When the labyrinth was stimulated with the head facing forward, soleus muscle activities increased on the right side and decreased on the left, with a latency of about 100 ms. In spite of the same stimulation, activities of the soleus muscle on both sides decreased with the head rotated to the right and increased with the head rotated to the left. 2) The responses in upper-body rotation were the same as in the case of head rotation. 3) In trunk rotation, some cases showed the same responses as with the trunk facing forward in rotation to the right and left, while others showed changes in muscular activities with the head rotation caused by rotating the trunk. 4) Changes in labyrinthine evoked EMG by head and trunk positions were considered to be due to interaction of vestibular and proprioceptive inputs on the interneurons of the spinal cord.

Gait disturbances in patients with labyrinthine and cerebellar diseases.

In order to clarify the peculiarities of gait disturbances appearing in patients with labyrinthine and cerebellar disturbances, 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 and a data recorder with the aid of a five-channel telemeter. The power spectrum and correlation analyses were carried out with a PDP-11 computer. The following are results obtained from walking with the eyes closed. (1) On normal subjects, the power spectrum of U-D head movement indicated a rise at about 2 Hz. The autocorrelograms of U-D, R-L head movements and soleus muscle activities showed a chopping or sine wave process with an attenuation of amplitude. A cross correlogram revealed that when the head was inclined to the right side, the contralateral soleus muscle was active and when the head was inclined forward, one of the soleus muscles was active. (2) A patient with bilateral loss of labyrinthine function showed an increased R-L head sway and irregularly undulating F-B head movement, indicating disturbances of the labyrinthine righting and linear movement reflexes. (3) A patient with cerebellar atrophy indicated irregular U-D, R-L and F-B head movements. The soleus muscle activity changed irregularly.

Analysis of standing posture in patients with bilateral loss of labyrinthine excitability.

The forward-backward and right-left sways in the upright standing posture were examined using stabilometry and analysis with a 5-dimensional feedback model. The forward-backward sway was found to have a fast, hidden periodicity, composed of sways due to a loss of the labyrinthine righting reflex upon the head and interaction between the head and knee sways. Furthermore, on the basis of our previous investigation, the forward-backward sway was found to depend on the increased spinal reflexes caused by a loss of labyrinthine inhibitory control upon the antigravity muscles. The right-left sway is slow and irregular, being mainly produced by disturbance of the head righting reflex.

Clinical evaluation of medical treatment for Menière's disease, using a double-blind controlled study.

There are great variations in the clinical evaluations of the effectiveness of antivertiginous drugs for Meniere's disease. In our clinical evaluation, subjective and objective signs and symptoms of 128 patients with Meniere's disease and of 98 with other peripheral vestibular disorders were analyzed in a double-blind controlled study comparing adenosine triphosphate (ATP) (300 mg) and betahistine (36 mg) each given daily for 4 weeks. The method of administration was the matched-pair-group-method for this double-blind controlled trial. The attending physicians concluded that ATP was significantly more effective than betahistine in the treatment of Meniere's disease and other peripheral vestibular disorders.

[Huge jugular foramen neurinoma extending to the pharyngeal region: a case report].

The authors report a rare case of a huge jugular foramen neurinoma extending to pharyngeal region in a 64 year-old woman who visited an otolaryngologist with complaints of dysphagia, hoarseness and headache in 1984. At that time a submucosal lump was noted in her left pharyngeal region. Biopsy of the tumor proved it to be neurinoma. A CT scan disclosed a dumbell shaped jugular foramen neurinoma and noncommunicating hydrocephalus. Because her symptoms slowly progressed and cerebellar signs as well as signs of increased intracranial pressure was noted, she was referred to our hospital in 1986. She had shown typical sings of left Vernet syndrome, VIIth, VIIIth cranial nerve impairment as well as cerebellar, long tract and increased ICP signs. A subtotal removal was performed from the extracranial and posterior fossa in one stage. The tumor seemed to originate from the Xth cranial nerve. The histological diagnosis of neurinoma was confirmed. Postoperatively, although her dysphagia increased for several weeks, a tracheostomy was not necessary. She was discharged 2 months later and returned to her usual occupation as a house wife. Slight dysphagia and hoarseness were her only chronic symptoms. So far, 88 cases of jugular foramen neurinoma have been reported, 15 of them including our case from Japan. Our case is probably the largest of these reported tumors. Tumors in jugular foramen often masquerade as an acoustic neurinoma or other tumor. However, recently this can usually be diagnosed preoperatively with a careful neurological examination and by means of neuroradiological investigations such as jugular venography, CT scan and MRI.

Analysis of the vestibulo-spinal system with a five-dimensional feedback model.

The role of the vestibulo-spinal system involved in the maintenance of upright standing posture was studied by a time series analysis with a 5-dimensional feedback model. The system was composed of sways of the head, shoulders, hips and activities of the nuchal and soleus muscles. The results were displayed as determinants of noise correlation matrix, power spectrum, correlogram, transfer function and relative power contribution. The five movements constitute a feedback system in normal subjects. Bilateral loss of labyrinthine function indicates a break in the feedback system. The power spectrum and relative noise contribution indicate that the vestibulo-spinal system regulates low-frequency body sway in upright standing. However, the contribution of the system was low in the overall control of standing posture.

Dynamic characteristics of the otolithic oculomotor system.

Vertical eye tracking test, up-down test, and running test in the dark and light were carried out to obtain Bode plots of transfer function of the opto-oculomotor, otolithic oculomotor, and opto-otolithic oculomotor systems. 1. The gain and phase of the opto-oculomotor system obtained from the vertical eye tracking test were flat in a frequency range of 0.3 to 1.0 Hz. 2. During the up-down test in the dark, the gain of the otolithic oculomotor system linearly increased at the rate of 20 dB/decade with an increase of frequency from 0.7 to 5 Hz. 3. During the up-down test in the light, the gain and phase were flat in a frequency range of 0.3 to 2.5 Hz. 4. The transfer function calculated with vertical head acceleration as input and vertical eye movement as output in the running test in the dark was similar to that in the light. The gain linearly decreased at the rate of 40 dB/decade with increase of frequency from 0.3 to 3.0 Hz. During running, eye displacement is almost in proportion to the head displacement in both dark and light. In daily, active movement such as running, eye movement proportional to head displacement appears without collaborative action of the opto-oculomotor system. 5. All five patients with bilateral loss of labyrinthine excitability exhibited a similar opto-oculomotor response to that of normal subjects. Three of the five patients did not show any eye movement corresponding to head movement in the up-down test in the dark. However, two patients showed a periodic eye movement in the same test, indicating dispersion of the gain and phase values. 6. These patients exhibited a rhythmic eye movement corresponding to head movement in the running test in the dark and light. However, values of gain and phase obtained in both tests were cultured. The variations in gain obtained from the running test in the light were observed in frequency ranges above and below 1 Hz.

A quantitative test of optokinetic nystagmus and its data processing by computer.

A quantitative test of optokinetic nystagmus was proposed. Horizontal nystagmus was examined by a large rotating cylinder with vertical stripes. Nystagmus responding to the cylinder rotation with an acceleration of 2 degrees/sec2 for 90 seconds was recorded with an electronystagmograph. On the records, the number of beats, average eye-speed, and average amplitude per each 10 seconds were calculated. This method was suitable for testing the nature of optokinetic nystagmus which indicates the ability of the eyes to adapt to objects moving through the visual field. Moreover, in order to save trouble in hand-scoring of each parameter of nystagmus, computer processing of electronystagmographic data was introduced. The results were printed numerically on the teletypewriter, and displayed graphically on a cathode ray tube and X-Y recorder. By displaying measured values on the form already printed with the normal ranges, the evaluation of the results was performed readily and objectively.