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Biomedical subjects

I Koizuka

Publications and source records attributed to I Koizuka.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Three cases of Lermoyez's syndrome and its pathophysiology].

Two cases of bilateral Lermoyez's syndrome and one case of unilateral Lermoyez's syndrome are reported. The patients had recurrent episodes of vertigo with improvement of hearing or tinnitus, which is characteristic is Lermoyez's syndrome. In case 1, a 48-year-old female, dehydration with glycerol or furosemide induced nystagmus and improved bilateral hearing and the gain of the vestibulo-ocular reflex, while overhydration with drinking water impaired bilateral hearing with disappearance of nystagmus. These findings indicate that she had endolymphatic hydrops in both ears, suggesting that simultaneous changes in bilateral cochlear and vestibular function induce Lermoyez's syndrome. In case 3, a 52-year-old female, which we already reported, endolymphatic collapse in both ears may have changed bilateral inner ear function, resulting in Lermoyez's syndrome. On the other hand, patients 2, a 47-year-old male, experienced a vertigo attack with improvement of unilateral hearing after defibrinogenation therapy. In this case, slowly developing insufficiency of the inner ear blood supply may have caused the gradual hearing loss. It seemed that decreasing blood viscosity by defibrinogenation allowed blood to rush into the labyrinth, causing vertigo but at the same time improving hearing. We proposed that there are two types of Lermoyez's syndrome, bilateral (cases 1 and 3) and unilateral (case 2).

Endolymphatic Hydrops↗
PubMed1995

Time course of vestibular function in patients with menière's disease following vestibular nerve section.

Harmonic acceleration rotational test and vestibular autorotation test (VAT) were performed on 8 patients with Menière's disease before and after vestibular nerve section. Sinusoidal rotations of 0.01-0.64 Hz were used in the HA rotational test. VAT was performed at frequencies between 0.5 and 6 Hz. Two weeks after operation, almost all the patients consistently showed response asymmetry toward the healthy ear at all stimulus frequencies and a reduction in sensitivity to rotational stimuli at 0.01 Hz in the HA rotational test. Prior to surgery, the time constant of the vestibulo-ocular reflex (VOR) varied according to the residual vestibular function of each patient. The time constant then dropped to a mean of 4.2 s after the operation. In the VAT, almost all the patients showed a gain reduction at all frequency ranges on the seventh postoperative day. These findings suggest that response asymmetry and gain at 0.01 Hz in the HA rotational test are valuable for evaluating the time course of the compensation of the vestibular function after surgery and that the VOR time constant is useful in detecting whether the vestibular nerve has been sectioned correctly.

Adult↗
PubMed1995

Clinical investigation of the vestibular cortex.

This study attempted to identify the vestibular cortex that is involved in the perception of vestibular vertigo in the human brain. We used single-photon emission computed tomography (SPECT) to measure regional cerebral blood flow (rCBF) in two cerebrovascular patients with nystagmus-sensation dissociation, which is known as brisk caloric nystagmus without simultaneous sensation of vertigo. Both patients had ischemic lesions involving mainly the parieto-temporal lobe in the nondominant hemisphere. It is suggested that the parieto-temporal lobe in the nondominant hemisphere contains the vestibular cortex which is a center for the perception of vertigo due to vestibular stimulation.

Aged↗
PubMed1995

High-resolution MRI of the human cochlea.

The majority of magnetic resonance imaging (MRI) studies in neurotology concern the evaluation of retrocochlear pathologies or temporal bone lesions. Recently, quite a number of investigators have attempted to use imaging diagnosis to obtain a diagnosis and manifest the pathological findings of Meniere's disease. However, there is no evidence that endolymphatic hydrops in patients with Meniere's disease can be identified by imaging techniques. In this study we could depict Reissner's membrane clearer than before with the use of image processing. At the present time, we cannot apply the 2.11T MRI machine to patients under FDA regulation. We believe that MRI diagnoses of endolymphatic hydrops and small lesions of the internal structures of the inner ear will be possible in the near future.

Adult↗
PubMed1995

Nystagmus measured by ENG after stapes surgery.

Much attention has been paid to hearing results after stapes surgery, but the risks of vestibular disturbance has not been extensively studied. Postoperative spontaneous nystagmus was measured daily at bedside by portable ENG in order to evaluate the vestibular damage from stapes surgery. Thirteen patients underwent primary stapedotomy or stapedectomy from August 1, 1992 to June 30, 1993. Nystagmus toward the operated ear was observed in 3 cases, that toward the opposite ear in 2 cases, that changing from toward the operated ear to toward the opposite ear in 2 cases, that changing from toward the opposite ear to toward the operated ear in 2 cases and no nystagmus in 4 cases. There was no relationship between duration of nystagmus and that of dizziness. Nystagmus was thought to be due to the following: i) inner ear damage by operation, ii) postoperative perilymphatic fistula, iii) floating footplate, and iv) stimulation of hair cells by high potassium ion in the perilymph due to blood flow into the inner ear.

Adolescent↗
PubMed1995

Assessment of auditory and vestibular functions after vestibular neurectomy for Menière's disease.

Fourteen patients (12 Meniere's disease, one delayed endolymphatic hydrops and one labyrinthitis) suffering from intractable vertigo were treated with retrosigmoid vestibular neurectomy (RSVN) in our institute. Dizziness was controlled completely in all patients. Hearing was preserved in 91.7% of the cases with pure tone threshold deteriorating by more than 10 dB in one case, remained unchanged in 10 cases and improved in one case during long term observation. Substantial decrease of tinnitus was observed in 78.6%. Vestibular compensation was chronologically analyzed with a stabilometer, ENG and vestibular rotation test (0.01-0.64 Hz). Vestibular compensation under static conditions was accomplished within 2 weeks, except for spontaneous nystagmus measured in the dark. Asymmetry of vestibulo-ocular reflex was noted 2 weeks after the operation but had disappeared after 4 weeks. However, for over 2 years the VOR time constant remained lower (4.3-5.2 s) than the pre-operative value (8.2 s). Electro-cochleogram (ECoG) was recorded before and after RSVN. The -SP/AP ratio tended to increase after RSVN in the operated ear, though there was no change in the contralateral ear. The efferent olivo-cochlear bundle was thought to play a potential role in this increase of the -SP/AP ratio.

Adult↗
PubMed1995

[Multivariate analysis of everyday handicap of patients with dizziness].

A preliminary questionnaire consisting of 30 questions was developed to evaluate handicaps in everyday life for 105 patients with dizziness. Factor analysis divided the questions into 5 principal factors of handicap due to dizziness: 1) disturbance of social activity, 2) body motion precipitating dizziness, 3) limitation of physical activity, 4) emotional disturbance, and 5) disturbance of interpersonal communications. The score of each factor was calculated as the sum of the scores of three principal questions in the corresponding factor. There was no contribution of clinical diagnosis, patient's age or gender, or duration of the disease to the score of each factor. Thus, it is concluded that the reorganized questionnaire which consists of three principal questions in 5 factors can be used for evaluating dizziness handicaps in everyday life. The score of the emotional factor in patients with Meniere's disease was higher than that for other vestibular disease. The score of the body motion factor in patients with vestibular neuronitis was higher than that for vertebro-basilar artery insufficiency. Thus, the re-organized questionnaire can also be used for evaluating the contribution of each factor to dizziness handicaps in everyday life.

Activities of Daily Living↗
PubMed1995

[Diagnostic and therapeutic problems in vestibular neuronitis: clinical implications for sudden vertigo].

We defined sudden vertigo as a sudden, unilateral peripheral vestibular dysfunction. The criterion for its diagnosis is a single episode of vertigo without cochlear and central symptoms. Among 20 patients with sudden vertigo there was no difference in clinical aspects between those with CP (canal paresis) (CP% > or = 25%) and those without CP (CP% < 25%). This suggests that sudden vertigo with CP is due to sudden vestibular dysfunction with predominant involvement of the lateral semicircular canal. Basically, vestibular neuronitis is considered to be due to acute unilateral neuropathy of the vestibular nerve. However, since we have no routine examination for evaluating vestibular nerve function, sudden vertigo with CP should be diagnosed as vestibular neuronitis. We then assessed the prognosis of sudden vertigo with CP (vestibular neuronitis). About two years after the onset of CP 4 of 10 patients had recovered. However, patients with persistent CP had a handicap in their everyday life because of the dizziness induced by head movements. The possibility of recovery of vestibular function in response to steroid therapy may improve the prognosis in vestibular neuronitis.

Adult↗
PubMed1993

Nystagmus responses in normal subjects during eccentric sinusoidal rotation.

Earth vertical axis rotation provides a method of stimulating the horizontal semicircular canals. By placing subjects off from the axis of rotation, the otolith organs may also be stimulated by additional linear acceleration forces. In the present study, we compared the rotation with subjects placed on axis to those placed in an eccentric position, either facing outward or turned 90 degrees facing the direction of the rotation. When the subject was facing outward, sinusoidal eccentric rotation at 0.64 Hz produced a significantly higher vestibulo-ocular reflex (VOR) gain than did on-axis rotation. No increase in VOR gain was observed during eccentric rotation with the subject facing the direction of the rotation. These findings suggest that the gain enhancement due to eccentric rotation is a result of tangential linear acceleration, probably sensed by the utriculus. This study raises the possibility of using eccentric rotation for the diagnosis of the patients with otolith dysfunction.

Acceleration↗
PubMed1992

Vestibular, central and gastral triggering of emesis. A study on individual susceptibility in rats.

Using kaolin intake as a behavioral index of emesis in rats, we examined the relationship between susceptibility to motion sickness and to emesis induced by apomorphine or copper sulfate. Rats showed a wide variation in susceptibility to motion sickness. Significant positive correlations were found between susceptibility to motion sickness and to emesis induced by intraperitoneal administration of apomorphine and by oral administration of copper sulfate. Motion, apomorphine and copper sulfate induce emesis through different receptors, so these findings suggest that the sensitivity of a common locus of emesis, presumably the emetic center in the brain stem, is one determinant of individual differences in susceptibility to motion sickness.

Animals↗
PubMed1991

High-resolution magnetic resonance imaging of the human temporal bone.

A magnetic resonance imaging (MRI) system (Hitachi, Naka, Japan) with a superconductive magnet running at 2.11 T was used to obtain 2-mm-thick slices of fixed, decalcified and celloidin-embedded human temporal bone. The temporal bone was then sectioned and stained for routine histological evaluation. Both the MR images and the histological sections were in the mid-modiolar slice plane, and comparable images and sections were analyzed to confirm the identity of the inner-ear structures visualized on the MR images. The cochlear duct, scala tympani, scala vestibuli and basement membrane of all three cochlear turns were clearly imaged on MRI. In addition, the vestibule and three semicircular ducts were also clearly seen. This study raises the possibility of some day using MRI for the diagnosis of inner-ear diseases.

Basement Membrane↗
PubMed1991

Effects of otolith stimulation in eccentric rotation on the vestibulo-ocular reflex in squirrel monkeys.

When a subject is rotated around an axis located behind his head (eccentric rotation, ECR), he experiences a combination of angular acceleration and two kinds of linear accelerations, tangential and centrifugal. The effects of stimulation of the otolith organs by linear acceleration in ECR on gain of the vestibulo-ocular reflex (VOR) were examined in squirrel monkeys. The VOR gain in ECR with the animal's head facing away from the rotation axis was significantly higher than that in centric rotation (CR) at 1.0 Hz, but not at 0.5 Hz. However, the VOR gain did not increase in eccentric-lateral rotation when the animal faced tangentially, even at 1.0 Hz. After bilateral ablation of the otolith organs (sacculectomy and utricular neurectomy), the VOR gain in ECR did not increase, even at 1.0 Hz. These findings demonstrate that tangential acceleration along the interaural axis in ECR stimulates the utricular maculae, resulting in enhancement of the VOR gain. The results also suggest that ECR is a useful clinical test for the function of the otolith organs.

Animals↗
PubMed1991

Centric and eccentric VOR tests in patients with Menière's disease and vestibular Menière's disease.

Pendular rotation in the eccentric position produces the same angular stimulation as that in conventional pendular rotation and, in addition, involves linear centrifugal and tangential acceleration forces which act on the otolith organs. In the eccentric position, normal subjects showed an increase in gain at 0.64 Hz, when compared with the gain with the head in the centered position. Therefore, we concluded that it is possible to diagnose otolith dysfunction by this comparison. In this study, we applied centric and eccentric pendular rotation tests to patients with Menière's disease and vestibular Menière's disease and investigated their otolith function. Patients with Menière's disease or vestibular Menière's disease within 1 month after the first attack or the most recent attack showed no gain enhancement with eccentric rotation. However, others showed gain enhancement with eccentric rotation. Therefore, we concluded that there seems to be no difference in the otolith function, especially in utricular function between Meniere's disease and vestibular Menière's disease.

Adult↗
PubMed1989

Effects of ethyl alcohol and heavy-water administration on vestibulo-ocular reflex in rabbits.

The effects of ethyl alcohol and heavy water on the long-time constant (T1) of the vestibulo-ocular reflex, an index of the dynamics of the cupula-endolymph system of the semicircular canal, were investigated in rabbits. Ethyl alcohol with a specific gravity of 0.793 caused two types of direction-changing positional nystagmus. In the early period after its administration, geotropic type positional nystagmus was induced. In this period, ethyl alcohol reduced T1. In the later period after its administration, apogeotropic type positional nystagmus was induced. In this period, T1 was again prolonged. Heavy water with a specific gravity of 1.10 caused apogeotropic type positional nystagmus and prolonged T1. These findings demonstrated that ethyl alcohol and heavy water directly affect the cupula-endolymph system, suggesting that the semicircular canal was responsible for the positional nystagmus.

Animals↗
PubMed1988

Clinical observations in the acute phase of cerebellar hemorrhage and infarction.

Three cases of cerebellar hemorrhage and 5 of cerebellar infarction, diagnosed by brain CT, were examined from the early phase of the onset. All of our cases were mild to moderate in severity and were cured satisfactorily within 3 to 8 weeks of medical treatment. Dizziness and nausea were the commonest symptoms and cerebellar and other CNS signs could be detected only for a short period in some of the cases. Although neuro-otological examinations, especially gaze nystagmus, eye tracking and positional nystagmus tests, were useful for diagnosing the central vestibular lesion, no definite indication could be drawn in order to differentiate between cerebellar hemorrhage and infarction. Therefore, it is considered difficult in such mild cerebellar strokes to establish correct diagnosis by physical examinations alone. It was concluded that if central vestibular disorder is suspected, prompt brain CT examination is necessary in order to diagnose mild cases of cerebellar vascular diseases.

Cerebellar Diseases↗
PubMed1988

ENG findings in patients with Bell's palsy. Relationship between visual suppression and clinical course.

Electronystagmography (ENG) is known to be a useful method for the evaluation of vestibular disorders. We tested 40 Bell's palsy patients who visited our clinic within 3 weeks after the onset of paralysis with ENG. Regarding the ENG findings and facial nerve damage, there were no correlations between the severity of paralysis in the initial period and the degree of paralysis recovery and existence of spontaneous, positional and positioning nystagmus. Patients with CP had a significantly severe paralysis in the initial period, but then showed varying degrees of recovery from the paralysis. Appearance of DP was not dependent upon the severity of facial paralysis in the initial period or the degree of paralysis recovery. Patients without visual suppression had a more severe paralysis in the initial period and a poor paralysis recovery at 3 months after the onset of paralysis.

Adolescent↗
PubMed1984

In vivo 31P-NMR studies on aerobic recovery of frog muscle following tetanus.

Aerobic recovery after a 60-sec tetanus of skeletal muscle of frog was studied using the in vivo 31P-NMR method with a topical magnetic resonance spectrometer (TMR) at 17 degrees C. Creatine phosphate recovered with a time constant of about 25 min-1. Sugar phosphates increased by the Pasteur effect, and saturated at about 4.5 mmol/kg muscle. The high level of the sugar phosphates was sustained during the following 60 min.

Adenosine Triphosphate↗