Biomedical subjects

M Kitahara

Publications and source records attributed to M Kitahara.

At least 73 records · Page 4Linked to original sources

PubMed1995

Clinical findings in Menière's disease with bilateral fluctuant hearing loss.

Our department conducted an examination of the clinical characteristics of Menière's disease with bilateral fluctuant hearing loss, using data obtained in a survey involving sixteen institutes associated with the Vestibular Disorder Research Committee, Japan. A total of 480 cases were surveyed, of which 204 showed normal hearing in the second ear, and were thus classified as unilateral Menière's disease, or Menière's disease with unilateral involvement; 135 cases showed fluctuating cochlear symptoms in the second ear, and were therefore classified as Menière's disease with bilateral fluctuant hearing loss or bilateral involvement. Our results show that patients with bilateral involvement experience increased disruption of daily life activities, and respond poorly to therapy with diuretics or steroids. Hospitalization is often considered for these patients. For these reasons it is especially important that bilaterality be diagnosed as early as possible, and that intensive treatment be carried out. ENT specialists must recognize the seriousness of bilateral involvement, and take particular precautions against its occurrence.

Activities of Daily Living↗

PubMed1995

Epidemiological study of severe cases of Meniére's disease in Japan.

In order to clarify the characteristics of severe cases of Meniére's disease (MD), we analyzed various epidemiological factors such as sex ratio, past history, complication, cause of onset of vertiginous attacks, etc., in a series of 958 patients with definite MD. Data were obtained from the three Japan-wide surveys of MD conducted by the Meniére's Disease Research Committee of Japan (1975-76) and the Vestibular Disorders Research Committee of Japan (1982-84 & 1990). Following the ideas proposed by the members of the Vestibular Disorder Research Committee of Japan, we divided severe cases into three categories according to the following criteria i) bilateral MD cases (BMD), ii) unilateral MD cases with prolonged disabled vertigo (UPDV), iii) unilateral MD cases with profound hearing loss (UPHL). About 40% of the subjects were classified as severe cases (UPDV: 23%; BMD: 9%; UPHL: 6%). The ratio of otitis media in past history was statistically different between severe cases and non-severe patients (p < 0.05), suggesting that otitis media in the past may contribute to the severity of Meniére's disease.

Adolescent↗

PubMed1995

[A case of ruptured true posterior communicating artery aneurysm thirteen years after surgical occlusion of the ipsilateral cervical internal carotid artery].

A case is presented of ruptured "true" posterior communicating artery aneurysm thirteen years after surgical occlusion of the ipsilateral cervical internal carotid artery. A 58-year-old female developed the sudden onset of blepharoptosis on the right side. She had had a right superficial temporal artery-middle cerebral artery anastomosis and a surgical occlusion of the right cervical internal carotid artery 13 years earlier for a subarachnoid hemorrhage that occurred as the result of a ruptured aneurysm of the right internal carotid artery. Neurological examination on admission revealed an occulomotor palsy on the right. Cerebral angiograms demonstrated an aneurysm arising from the right posterior communicating artery itself near the right posterior cerebral artery. Also, the right intracranial internal carotid artery was supplied through the right posterior communicating artery. Five days later she experienced the sudden onset of severe headache. CT scan showed subarachnoid hemorrhage in the ambient cistern. Neck clipping of the aneurysm was successfully performed by the contralateral zygomatic approach. The postoperative course was uneventful. It has been well known that internal carotid artery occlusion may be associated with cerebral aneurysm in some cases. However, it seems to be very rare that a "true" posterior communicating artery aneurysm should occur following the ipsilateral carotid artery occlusion. Hemodynamic factors were strongly suggested as the reason for aneurysmal formation in this case.

Aneurysm, Ruptured↗

PubMed1994

Lysophosphatidic acids induce proliferation of cultured vascular smooth muscle cells from rat aorta.

Lysophosphatidic acids (LPA) with a C18 fatty acyl group accelerated thymidine incorporation into cultured rat aortic vascular smooth muscle cells and stimulated their cell division. LPA acted synergistically with epidermal growth factor and fibroblast growth factor but additively with platelet-derived growth factor. The stimulatory actions of LPA were suggested to be rather specific from the following findings: 1) their stimulation of DNA synthesis increased with an increase in their acyl moiety; 2) lysophosphatidylcholine, a neutral lysophospholipid, had no mitogenic action but was cytotoxic at high concentrations; and 3) LPA induced a rapid external Ca(2+)-independent increase in intracellular Ca2+ concentration ([Ca2+]i) in single fura 2-loaded cells that resembled the receptor-mediated increases in [Ca2+]i triggered by different agonists, whereas lysophosphatidylcholine provoked a slow sustained increase in [Ca2+]i in an external Ca(2+)-dependent manner. These results are discussed in relation to the possible pathophysiological role of LPA.

Animals↗

PubMed1994

[Effect of efonidipine hydrochloride (NZ-105), a new dihydropyridine calcium antagonist, on the experimental atherosclerosis in cholesterol-fed rabbits].

We studied the effect of efonidipine hydrochloride [NZ-105:(+-)-2-[benzyl(phenyl)amino]ethyl 1,4-dihydro-2,6-dimethyl-5- (5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl )-3-pyridine-carboxylate hydrochloride ethanol], a newly synthesized dihydropyridine calcium antagonist, on atherosclerosis in 1% cholesterol-fed rabbits. NZ-105 (10, 30 and 100 mg/kg) was orally administered to the animals twice a day for 10 weeks. NZ-105 did not cause any significant change in the plasma lipid levels. The area of atherosclerotic lesion was reduced by 37% (P < 0.05) in the aortic arch and by 54% (P > 0.05) in the thoracic aorta of rabbits administrated 100 mg/kg of NZ-105. The content of cholesterol ester in the aorta was also reduced by 64% (P < 0.05) in the aortic arch and by 73% (P > 0.05) in the thoracic aorta. These results suggest that NZ-105 may suppress the development of atherosclerosis without affecting the plasma lipids.

Animals↗

PubMed1994

The influence of middle ear pressure changes on the primary vestibular neurons in guinea pigs.

The responses of primary vestibular neurons and perilymphatic pressure changes to middle ear pressure stimuli in guinea pigs were investigated in order to clarify the direct effects of pressure stimulus on the vestibular apparatus. The vestibular response was related to the amount of middle ear pressure change applied at a rate of +/- 100 mmH2O/s. The neural response rates of vestibular units to positive pressure in the middle ear were significantly larger than those to negative pressure. The time course pattern of the perilymphatic pressure change resembled that of the response of the vestibular units, indicating that the vestibular response is elicited by middle ear pressure via the pressure transmitted in the inner ear.

Animals↗

PubMed1994

The influence of vestibular and cochlear aqueducts on vestibular response to middle ear pressure changes in guinea pigs.

The responses of primary vestibular neurons and perilymphatic pressure changes to middle ear pressure were investigated in guinea pigs with obstructed vestibular or cochlear aqueduct (closed VA or closed CA group) in order to clarify the influence of VA and CA on pressure-induced vestibular response. Although the neural response rates and the amount of perilymphatic pressure change in the closed VA group resembled those in the control group, these values in the closed CA group were higher than in the control group. Patency of the CA had a more significant effect on the vestibular response to middle ear pressure change than patency of the VA.

Animals↗

PubMed1994

Swimming test for evaluating vestibular function in guinea pigs.

A swimming test was used to evaluate vestibular function in guinea pigs. We first observed tracings of the swimming patterns of 20 healthy guinea pigs to establish the normal range. Then the same test was used in a group of 49 guinea pigs with endolymphatic hydrops induced by immunologic techniques. They did not show spontaneous nystagmus or body deviation while walking, but a total of 20 out of 49 animals displayed abnormal swimming patterns, with 8 swimming clockwise and 4 counterclockwise. This swimming test is easily able to detect mild vestibular dysfunction in guinea pigs, and can be repeated, so that we consider it useful for examining vestibular function in these animals.

Animals↗

PubMed1994

Electrocochleography in experimental endolymphatic hydrops.

This study investigated whether dominant negative summating potential (DNSP) is absent at all stages of induced hydrops development, including the early stages of hydrops formations. Electrocochleography (ECoG) was done 3 days to 20 weeks after obliteration of the endolymphatic sac in guinea pigs, by electrodes attached to the cochlear bony wall on the scala vestibuli of the basal turn. DNSP was noticed only during the early stages of endolymphatic hydrops formation, before hydrops was fully developed. There was no DNSP when the distension of Reissner's membrane was marked. Increased endolymphatic pressure and/or changes in biochemical composition were thought to be the causes of DNSP.

Action Potentials↗

PubMed1994

Endolymphatic sac blood flow versus cochlear blood flow following intravenous administration of isosorbide in guinea pigs.

Endolymphatic sac (ES) blood flow (ESBF) and cochlear blood flow (CBF) were measured in different groups of guinea pigs by laser-Doppler flowmetry (Advance Laser Flowmeter, Model ALF 2100) after the intravenous administration of 70% isosorbide (1.6 ml/kg). The measurements were made under general anesthesia with intraperitoneal pentobarbital sodium. Respiration was controlled by a respirator after tracheotomy, and blood pressure was monitored through the femoral artery (Gould Statham P23 ID Pressure Transducer). For ESBF measurements, a probe was placed on the right ES after entering the posterior cranial fossa via the dorsal approach. For CBF measurements, a probe was placed on the basal turn of the right cochlea via the ventral approach. Isosorbide was administered intravenously through the jugular vein for 60 s. Both ESBF and CBF increased immediately after administration, reached a peak within 3-6 min and decreased gradually to their initial baseline levels in 11-15 min. Both blood flow changes almost always corresponded to systemic blood pressure changes, although a slight delay was observed in blood pressure compared to the blood flow. The magnitude of the CBF response tended to be greater than that of the ESBF response (p < 0.1). This may result from the anatomical differences in the two blood supplies, i.e., from the vertebral artery (CBF) and the external carotid artery (ESBF).

Animals↗

PubMed1994

Acceleration registrography of head movement during alternating inclination of the support platform.

The righting reflex, essential for maintaining equilibrium, keeps the head and trunk in a state of balance with regard to gravity. Because patients suffering from vestibular disorders almost always complain of dizziness during everyday movements such as rising and walking, the righting reflex should be evaluated within the context of these dynamic states. A new method of acceleration registrography was designed to enable the testing of this reflex as the subject stands upon a moving platform. Participating in the study were 49 normal control subjects and 80 patients with peripheral vestibular disorders. The test we devised proved to be more successful in detecting labyrinthine righting reflex dysfunction in patients than the tests of righting reflex and deviation evaluations used thus far, such as Romberg's, Mann's and the stepping test, and to more accurately represent the disequilibrium and/or dizziness experienced by patients in everyday movements.

Acceleration↗

PubMed1994

Influence of passive and active pendular head rotation on horizontal optokinetic nystagmus.

The influence of pendular head rotation on optokinetic nystagmus was examined using a vestibulo-optic stimulator (pendular rotating chair with an optic cylinder) to study passive head rotation, and an optic cylinder which was rotated by a motor fixed to the head to study active head rotation. Pendular head rotation and optic stimuli were simultaneously and independently applied horizontally. The optic cylinder consisted of 12 vertical stripes rotating at a uniform velocity of 30 degrees/s or 90 degrees/s. Passive pendular head rotation was applied at a frequency of 0.1 Hz and a peak angular velocity of 30 degrees/s. Active head rotation was applied for a period of approximately 10 s, and at an amplitude of approximately 50 degrees. Optokinetic nystagmus was enhanced when the head was rotated in the opposite direction to the optic cylinder. However, when the head and the optic cylinder were rotated in the same direction, optokinetic nystagmus was inhibited. There was little difference between the effects of passive and active head rotation on enhancement. However, during active head rotation, optokinetic nystagmus was less inhibited than during passive head rotation.

Adult↗

PubMed1994

Air caloric test with continuous thermal change.

A new technique was designed for vestibular testing with an air caloric stimulator. With this technique, the temperature threshold necessary to induce caloric nystagmus was measured as air temperature decreased at a constant rate (from 37 degrees C). As a pilot study, an air caloric test with continuous thermal change was done at 6 different rates of decrease: 0.01, 0.03, 0.05, 0.1, 0.15 and 0.2 degrees C/s. The rate of 0.05 degrees C/s gave the smallest standard deviation for temperature threshold in normal subjects. This deviation had the narrowest normal limits of all ordinary caloric tests when the coefficient of variation was compared (standard deviation/mean x 100). No discomfort was observed during or after the air caloric test with continuous thermal change at this rate.

Air↗

PubMed1994

Three-dimensional audiogram.

We used a three-dimensional audiogram which displays duration of the disease on the X-axis, frequency on the Y-axis, and hearing level on the Z-axis, to aid observation of hearing changes during the course of various otologic diseases. An overall, quantitative view of the changes in a patient's hearing level with time was easily obtainable with this technique, as the temporal element is shown on the X-axis. The basal view position of the three-dimensional audiogram displays most of the information necessary to form a diagnosis, determine treatment, and evaluate is efficacy in various otologic diseases. The three-dimensional audiogram was found to be most useful in observing changes in hearing level in sudden deafness, with its often rapid recovery period, and Meniere's disease, with its long-term fluctuating hearing loss. In some patients, a better understanding of the hearing changes could be obtained from a view angle other than the basal view position.

Adult↗

PubMed1994

Assessment of prognosis in sudden deafness.

We investigated the usefulness of three-dimensional audiograms in assessing prognosis during the early phase in 116 patients with sudden deafness. The initiation time of improvement in middle-frequency hearing at 15 dB or more was valuable in assessing prognosis in patients with deafness and scale-out types of hearing loss. Improvement within 13 days in patients with the deafness type, and within 17 days in those with the scale-out type, was correlated with a high incidence of marked improvement or complete recovery. Patients with an initial mean hearing level below 80 dB, or in whom the glycerol test and electrocochleography results suggested the presence of endolymphatic hydrops, had a good hearing outcome. Patients without tinnitus showed an unfavorable hearing outcome.

Adult↗

PubMed1994

Tinnitus evaluation using the tinnitus grading system.

We developed a system to help evaluate the likelihood of a particular patient requiring intensive tinnitus treatment. The system is based on Vernon's tinnitus grading system, in which patients assign values from 1 to 5 to each of the three subjective complaints of loudness, annoyance, and interference with life activities. In our study, we collected data from 346 of our tinnitus patients and analyzed the relationship between the three values. On the basis of these results the patients were divided into five tinnitus-type groups. Scores on a tinnitus severity scale were also determined by adding the three values together. We similarly evaluated 87 patients whose tinnitus was severe enough to require hospitalization. It was found that patients who had high values for annoyance and life interference and who showed tinnitus severity scores of 9 or more tended to require careful observation and intensive treatment. These patients also tended to have physical and psychological problems in addition to their tinnitus.

Activities of Daily Living↗

PubMed1994

Computerized tomography of the petrous bone in Menière's disease.

High resolution transverse axial computerized tomograph (CT) encompassing the lateral semicircular canal (LSC) was used to measure the size of the petrous bone in ears with bilateral (n = 13) and unilateral (n = 38) Menière's disease, and in ears with unilateral chronic otitis media (n = 25) as a control group. Measurements were made of the following 4 distances in the petrous bone; A: the distance between the posterior semicircular canal (PSC) and the posterior petrous surface (PPS) (P-P distance), B: the distance between the PSC and the LSC (P-L distance), C: the distance between the vestibule and the PPS (V-P distance), and D: the distance between the PSC and the anterior margin of the sigmoid sinus (P-S distance). The P-P and the V-P distances were significantly shorter in ears with Menière's disease, especially in ears with bilateral Menière's disease compared to the nonaffected ears in unilateral Menière's disease or ears with chronic otitis media. This tendency was clearer in the P-P distance than in the V-P distance. The P-L and P-S distances did not show any statistical difference between groups. The results indicate that bone development between the PSC and the PPS and between the vestibule and the PPS, which usually contains the endolymphatic duct and sac, is significantly poorer in ears with Menière's disease than in ears with chronic otitis media. Hypoplasia of the retrolabyrinthine region may be an important factor in the pathogenesis of endolymphatic hydrops.

Cephalometry↗

PubMed1994

Computerized tomographic findings in endolymphatic sac surgery in Menière's disease.

We correlated the surgical findings and the findings of computerized tomographic scans of the temporal bone in 38 ears from 38 patients with Menière's disease (31 unilateral and 7 bilateral) treated by endolymphatic sac (ES) drainage surgery between 1986 and 1991. At surgery, the position and size of the ES were recorded. The position of the ES was classified as one of three types according to Arenberg's parameters (type I, type II and type III) and the size of the ES was classified as large, intermediate or small. Scans encompassing the lateral semicircular canal were used to measure the minimum distance between the posterior semicircular canal and the posterior petrous surface (P-P distance). The P-P distance in 23 type III cases was significantly shorter (2.25 mm) than in 13 type II cases (3.39 mm). The P-P distance in 9 large-sized ES cases was significantly longer (3.99 mm) than in 20 intermediate-sized ES cases (2.40 mm) and in 9 small-sized ES cases (1.92 mm). Significant correlations were found in patients with Menière's disease between a short P-P distance and type III ES position, and also between a short P-P distance and an intermediate or small-sized ES.

Cephalometry↗