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Biomedical subjects

M Yasaka

Publications and source records attributed to M Yasaka.

At least 37 records · Page 2Linked to original sources
PubMed1998

Side-to-side differences of the common carotid artery diameter in presence of asymmetry of the circle of Willis or different vasculopathies.

Based on angiographic and carotid ultrasonographic findings in 60 patients with stroke or other diseases, we studied what factors affected the side-to-side differences of the common carotid artery diameter (CCAD). The side-to-side differences of the CCAD were within 0.7 mm in patients with normal cerebral angiogram, but a difference above 0.7 mm was found in many patients with asymmetry of the circle of Willis or different vasculopathies, such as the carotid artery occlusion, cerebral arteriovenous malformation and aortitis.

Aortitis↗
PubMed1998

Transoral carotid ultrasonography.

BACKGROUND AND PURPOSE: We attempted ultrasonographic evaluation of the distal extracranial internal carotid artery (ICA) using the transoral method (transoral carotid ultrasonography [TOCU]). METHODS: The subjects consisted of five healthy volunteers and seven stroke patients. Examinations were performed with a color Doppler flow imaging system equipped with convex array transducers (7 or 9.5 MHz), originally designed for transrectal use. After local anesthesia of the pharynx, we inserted a probe covered with thin gum transorally, touching the tip to the pharyngeal posterolateral wall. We then attempted to detect the ICA and measure flow velocity of the distal extracranial ICA using principal images obtained by TOCU. RESULTS: TOCU was successfully performed in all subjects without any difficulty. In the healthy volunteers, the ICA was identified at a depth of 2.2+/-0.6 cm and visualized as a vertical linear vessel 2.9+/-0.3 cm in length and bent slightly backward. The diameter and mean flow velocity of the distal extracranial ICA were 4.7+/-0.2 mm and 50+/-7 cm/s, respectively. In the stroke patients, some remarkable findings were obtained, including a narrow ICA with low flow velocity in a patient with possible ICA dissection, a lucent echo without flow signal in a patient with acute cardioembolic ICA occlusion, and decreased ICA flow velocity in a patient with ipsilateral MCA stenosis. CONCLUSIONS: These preliminary data demonstrate the potential applicability of TOCU to the evaluation of flow in the far distal extracranial ICA. TOCU definitely warrants further investigation in patients with carotid artery disease.

Adult↗
PubMed1998

Streptokinase in acute stroke: effect on reperfusion and recanalization. Australian Streptokinase Trial Study Group.

The Australian Streptokinase Trial was a randomized, double-blind, placebo-controlled trial, in which streptokinase (SK, 1.5 million IU I.V.) was given within 4 hours of stroke onset. In a subset of 37 patients, 99mTc-labeled D,L-hexamethylpropylene amine oxime single-photon emission computed tomography (SPECT) and/or transcranial Doppler (TCD) studies were performed before and after therapy to test the hypothesis that SK may improve the hemodynamic measures of reperfusion/recanalization rates (TCD parameter) within 24 hours. Eighteen patients received SK and 19 placebo. Baseline characteristics were similar in both groups, and there were no differences in clinical outcomes assessed at 3 months after stroke. Although there was no increase in the group mean perfusion defect or volume on SPECT after thrombolytic therapy, a larger number of patients demonstrating the combined end point of reperfusion or recanalization was seen in the SK group (13/14, 93%) than in the placebo group (7/14, 50%; p = 0.01). Although SK given within 4 hours of acute ischemic stroke appears to improve arterial patency/tissue reperfusion, this effect is neither early nor extensive enough to influence overall clinical outcome.

Acute Disease↗
PubMed1998

Successful application of three-dimensional transcranial power Doppler imaging in two stroke patients.

We applied a new technique of three-dimensional (3-D) transcranial power Doppler imaging to demonstrate the middle cerebral artery (MCA) in the 2 stroke patients. In the first patient, the 3-D power Doppler study clearly showed the horizontal portion, bifurcation, proximal portion of the upper and lower trunks, and the major branches of the lower trunk of the MCA. In the second patient, the 3-D power Doppler clearly revealed the proximal bifurcation of the left MCA. The 3-D transcranial power Doppler seems to be useful in making clear 3-D images of the MCA.

Cerebral Angiography↗
PubMed1998

[Pathophysiology and treatment of cardioembolic stroke].

To elucidate the pathophysiologic mechanism of cardioembolic stroke in elderly people and to devise therapeutic strategies for it, was analyzed 120 consecutive patients (77 men and 43 women aged 65 +/- 13 years) with acute cardioembolic stroke who were admitted within 7 days of the stroke onset. We compared underlying heart diseases. NIH stroke scale on admission, lesion size on computed tomography (CT), the relation between anticoagulant therapy and recurrence, complications during admission. ADL at discharge, recurrence, and death during the follow up period in three groups: patients aged less than 65 years (the young group), those aged from 65 to 74 years (the "non-old" group), and those aged more than 75 years (the "old old" group). In the "old old" group, non valvular atrial fibrillation (75.8%) was the most common underlying heart disease and so was rheumatic heart disease (33.3%) in the "non-old" group. NIH stroke scale score (median, 11) and the proportion of patients with a large lesion (> 3 cm) of CT were higher in the "old old" group than in the other two groups. Immediate anticoagulation (A/C) within 14 days of onset was performed in more than 70% of the "non-old" and the "young old" groups but in only 57.6% of the "old old" group. Stroke recurred more often in 34 patients who did not receive immediate A/C than in the 86 who did (11.8% v.s. 2.3%. Chi square test, p = 0.053). Hemorrhage during immediate A/C and other complications (infection and pulmonary embolism) were seen in 2 and 14 patients, respectively, in both the "young old" groups, but not in the "non-old" group. Good outcomes (able to walk with or without cane) were more common in the "non-old" group (78.9%) than the other groups (57.1%, Chi square test, p < (0.01). A/C after the acute stage was done in more than 80% of those in the "non-old" and the "young old" groups, but in less than 30% of those in the "old old" group (Chi square test, p = 0.0514). Survival without recurrence during the observation period (605 +/- 550 days) was significantly lower in the "old old" group than in the other two groups (log-rank test, p = 0.0091). Cardioembolic stroke in the elderly may be characterized as follows: (1) non valvular atrial fibrillation is the most common, (2) severe neurologic deficits on admission and large lesions on CT are noted, (3) complications (infection and pulmonary embolism) often occur, (4) A/C in both acute and chronic stages are done infrequently. Therefore, the indication and intensity of A/C for primary and secondary prevention and prevention of complications are important in management of cardioembolic stroke in the elderly.

Age Factors↗
PubMed1998

[Right-to-left shunt and atrial septal aneurysm in stroke patients: a contrast transesophageal echocardiographic study].

BACKGROUND: Transesophageal echocardiography (TEE) has been used to detect cardiac abnormalities including right-to-left shunt (RLS) and atrial septal aneurysm (ASA). The aim of this study was to elucidate frequency of RLS and ASA detected by contrast-TEE, and to evaluate the role of these abnormalities in stroke patients. METHODS AND RESULTS: We investigated prevalence of RLS and ASA in 504 patients suspected of stroke by using TEE. (mean age 62 +/- 12 y.o., stroke 491, non-stroke 13). The RLS was detected in 64 patients (12.7%), in whom 49 patients (9.7%) had the patent foramen ovale (PFO). The ASA was demonstrated in 10 patients (2.0%), and accompanied well with the RLS (six of the 10, 60%). The prevalent ratios of the RLS (33.8%), the PFO (26.8%), and the ASA (11.3%) in 71 patients with embolic stroke (brain embolism or TIA) of unknown cause were significantly higher than those in the other 433 patients (9.2%, 6.9%, 0.5%, respectively, p < 0.0001). Multiple logistic regression analysis showed that both the PFO and the ASA were independent risk factors (odds ratio: 3.8: p = 0.0002 and 16.6: p = 0.0008, respectively) for embolic stroke of unknown cause. CONCLUSION: It seems that the RLS, PFO and the ASA play a roll in developing embolic stroke of unknown cause.

Adult↗
PubMed1995

[The pathogenesis of brain infarction in the posterior cerebral artery territory].

In order to clarify the etiology of brain infarction in the posterior cerebral artery (PCA) territory, we investigated 85 patients (29 women and 56 men, mean age: 63.6 years old) with PCA territory infarction confirmed by computed tomography or magnetic resonance imaging. Patients with thalamic infarction alone were excluded from the present study. Cerebral angiography was performed in 72 subjects. The diagnosis of the mechanism of brain infarction was made on the basis of cerebral angiographic and echocardiographic (presence of cardiac disease as a potential embolic source) findings. Embolism was inferred when the presence of the patent PCA ipsilateral to the infarction, reopening of the occluded PCA or intraluminal filling defect was demonstrated by angiographic studies. In addition, we divided these patients into three groups according to potential source of emboli; cardiogenic, atherothrombotic (so-called artery-to-artery embolism) and embolism of undetermined origin. We diagnosed the patient to have thrombotic mechanism, when an occlusion of the PCA was demonstrated without presence of an embolic source (heart diseases or stenotic arterial lesions proximal to the occluded PCA). When the mechanism (embolic or thrombotic) could not be clearly distinguished, we categorized them "unclassified". When other apparent mechanisms such as arterial dissection, moyamoya disease etc, were demonstrated, we classified them in "miscellaneous". According to the above criteria, 50 patients (59%) were diagnosed as having embolism, only two patients (2%) had definite thrombosis, 28 patients (33%) "unclassified", and five patients (6%) "miscellaneous" (2 arterial dissection, 1 radiation vasculopathy, 1 migraine, 1 moyamoya disease).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Ultrasonographic evaluation of vertebral artery to detect vertebrobasilar axis occlusion.

BACKGROUND AND PURPOSE: We performed the present study to determine whether the site of occlusion in the vertebrobasilar circulation could be identified by the measurement of blood flow velocity in the bilateral vertebral arteries. METHODS: Using color-coded duplex carotid ultrasonography, we measured the time-averaged mean and end-diastolic flow velocities with incident angle correction in 130 bilateral vertebral arteries between the C3 and C6 segments of the spine in 65 stroke patients with or without occlusive diseases in the vertebrobasilar circulation. The site of occlusion was confirmed by cerebral angiography. The subjects included 12 patients with unilateral subclavian artery occlusion (SA group), 11 patients with unilateral occlusion at the origin of the vertebral artery (V1 group), 6 patients with unilateral vertebral artery occlusion before the branching of the posterior inferior cerebellar artery (V2 group), 14 patients with unilateral vertebral artery occlusion after the branching of the posterior inferior cerebellar artery (V3 group), 5 patients with basilar artery occlusion (BA group), 5 patients with unilateral posterior cerebral artery occlusion (PCA group), and 12 patients without any occlusive lesions in the vertebrobasilar circulation (control group). RESULTS: In the control group the mean and end-diastolic blood flow velocities were 25.5 +/- 6.9 cm/s and 16.2 +/- 4.3 cm/s, respectively, and the side-to-side differences of these velocities were 4.8 +/- 5.2 cm/s and 4.7 +/- 4.1 cm/s, respectively. All patients in the SA group demonstrated retrograde flow on the affected side. In the V1 group no flow signals were detected on the occluded side. In the V2 group the mean velocity (7.2 +/- 3.1 cm/s) was lower than in the control group, and the end-diastolic velocity was zero on the affected side. In the V3 group the mean and end-diastolic velocities (11.5 +/- 3.1 cm/s and 5.9 +/- 2.8 cm/s, respectively) on the occluded side were lower than in the control group. Flow velocities on the unaffected side were higher than those on the affected side in the SA, V1, V2, and V3 groups. However, there were no differences in flow velocity between the control, BA, and PCA groups. CONCLUSIONS: Measurement of vertebral artery blood flow velocity may help in localizing the site of occlusion in the subclavian and vertebral arteries.

Aged↗
PubMed1994

Reopening phenomenon in cardioembolic stroke observed by duplex carotid ultrasonography. Case reports.

The authors attempted to detect the reopening of an occluded artery within the carotid axis of acute cardioembolic stroke patients noninvasively by using duplex carotid ultrasonography. The timing of reopening as related to hemorrhagic transformation was also studied. For assessing the reopening phenomenon, quantitative measurement of flow velocity in the bilateral common carotid arteries was repeated in 10 patients who also underwent repeated angiography or autopsy. The ratio of the end-diastolic flow velocity (nonaffected/affected) was related to angiographic or autopsy findings. In 17 patients including the 10 cases mentioned, the occurrence of hemorrhagic transformation was related to the timing of reopening. The hemorrhagic infarction in this study was defined to be a hyperdense area in the basal ganglia on computed tomography. A significant decrease in the ratio of the end-diastolic velocity was observed in 6 patients, in whom the repeated angiography demonstrated reopening of the artery. Of the remaining 4 patients not showing a significant change, only 1 patient was found to have reopening. Reopening was detected in 12 of 17 cases. The timing was 2.5 hours after onset in 1, between days 2 and 5 in 6 cases, and after day 6 in 5 cases. Hemorrhagic infarction was found in 5 of the cases with reopening on days 2-5.

Aged↗
PubMed1994

Recurrent embolization during intravenous administration of tissue plasminogen activator in acute cardioembolic stroke. A case report.

Treatment with recombinant tissue plasminogen activator (rt-PA) has been applied in acute cardioembolic stroke to reopen the occluded vessel and improve the patient's neurologic deficit. However, the effect of this therapy on intracardiac thrombus has not been documented previously. A forty-five-year-old man with dilated cardiomyopathy developed acute cardioembolic stroke with disturbance of consciousness, right hemianopia, right hemiplegia, and global aphasia. Cerebral angiography demonstrated occlusion of the left middle cerebral artery trunk. Intravenous administration of 30 megaunits (MU) of recombinant tissue plasminogen activator was commenced two hours after the ictus and completed within sixty minutes. Cerebral angiography was repeated just after this treatment and demonstrated a new occlusion of the left intracranial internal carotid artery along with occlusion of a branch of the left external artery. The authors subsequently performed two-dimensional echocardiography and found a mobile thrombus in the left ventricle. In patients with intracardiac mobile thrombi, recombinant tissue plasminogen activator seems to accelerate breakup or detachment of the thrombi and subsequent recurrent embolization. Therefore, it seems better to pay attention to the presence of mobile intracardiac thrombus before commencing intravenous infusion of rt-PA.

Acute Disease↗
PubMed1994

[Valproate related syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--a case report].

We report an 82-year-old retired man who developed syndrome of inappropriate secretion of ADH (SIADH) caused by sodium valproate (VPA). He had been taking VPA for treatment of symptomatic epilepsy due to cardioembolic stroke. Although he was clinically asymptomatic, he was found to have decreased level of serum sodium concentration (128 mEq/l). Association of hyponatremia, normal urinary sodium concentration, high urine osmolality and increased concentration of serum ADH strongly suggested the presence of SIADH. There were no underlying disorders which can cause SIADH, such as malignant neoplasm with autonomous ADH release, non-malignant pulmonary diseases and active disorders of the central nervous system. Eight days after discontinuation of VPA administration serum sodium level increased (142 mEq/l) to the normal level. Then, we started the administration of VPA again to confirm that VPA was responsible for developing hyponatremia. As a result, he developed SIADH with hyponatremia (128 mEq/l) again, which improved after discontinuation of the administration. Therefore, we concluded that the SIADH might have been caused by administration of VPA. This is the first report on adverse effect of VPA causing SIADH.

Aged↗
PubMed1994

[Horner type anisocoria associated with brain infarction of the internal carotid artery axis].

Brain infarction caused by arterial occlusion of the internal carotid axis sometimes develops Horner syndrome. The purpose of this study is to clarify the characteristics and mechanism of "Horner type" anisocoria, which is one of the symptoms of Horner syndrome, in patients with brain infarction in regions supplied by the internal carotid artery (ICA). We studied 112 consecutive patients (71 males and 41 females, mean age of 60.8 +/- 12.3 years) with brain infarction with either ICA or the middle cerebral artery (MCA) occlusion, who were admitted to the National Cardiovascular Center within seven days after the onset of stroke. We examined differences in frequency of Horner type anisocoria and its duration after onset by the mechanism (embolic or thrombotic) and site (ICA proximal, ICA distal or MCA) of arterial occlusion. Horner type anisocoria was seen in 26 of 66 cases (39.4%) with embolic occlusion, which was more frequent than in those with thrombotic occlusion (8 of 46 cases, 17.4%) (p < 0.05). In the embolic occlusion group, Horner type anisocoria was seen in 17 of 32 cases (53.1%) with ICA occlusion, which was more frequent than in those with MCA occlusion (9 of 34 cases, 26.5%) (p < 0.05). Horner type anisocoria was more frequently seen in embolic (17 of 32 cases, 53.1%) than in thrombotic ICA occlusion (2 of 21 cases, 9.5%) (p < 0.01). The duration of Horner type anisocoria was shorter in patients with either distal ICA or MCA occlusion than in those with proximal ICA occlusion (p < 0.05). In patients with thrombotic occlusion, there was no distinct characteristics in between those ICA and MCA occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Antihypertensive drugs in acute stage of atherothrombotic infarction deteriorate the outcome].

To elucidate whether high blood pressure in acute brain infarction should be treated or not, we retrospectively investigated relationship of the use of antihypertensive agents in the acute stage with the area of hypodensity on CT examined one month after onset and functional outcome at discharge. Actual blood pressure value and diurnal fluctuation in the acute stage were also related to the infarct size and outcome. Subjects were compared of 32 atherothrombotic stroke patients with unilateral severe stenotic lesion (> or = 75% stenosis or occlusion) at the extracranial carotid artery or the horizontal portion of the middle cerebral artery confirmed by cerebral angiography. Seven patients (treated group) received antihypertensive drugs within 14 days of onset and the remaining 25 patients (non-treated group) did not. The data of frequent blood pressure measurements were available in five of the treated group and 24 of the non-treated group. There were no significant differences in the daily highest and lowest mean arterial blood pressure (MABP) between the two groups (124.8 +/- 11.8 mmHg vs. 118.5 +/- 13.5 mmHg and 101.9 +/- 10.4 mmHg vs. 104.4 +/- 12.6 mmHg, respectively). However, apparent circadian fluctuation of the MABP (the highest MABP--the lowest MABP > 25 mmHg) was more frequently seen in the treated group (3/5, 60%) than in the non-treated group (0/24, 0%) (chi 2 test, p < 0.01). Large infarcts (> or = 10 cm2) were more commonly found in the treated group (4/7, 57%) than in the non-treated group (1/25, 4%) (chi 2 test, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

[Ataxic hemiparesis with ipsilateral cheiro-oral syndrome due to a single lacunar infarct at the border between the posterior limb of the internal capsule and the corona radiata].

A patient with ataxic hemiparesis and ipsilateral cheiro-oral dysesthesia (tingling) due to a single lacunar infarct at the border between the posterior limb of the internal capsule and the corona radiata is described. A 47-year-old hypertensive man was admitted because of weakness of the right upper and lower limbs with ipsilateral peri-oral and palmar dysesthesia, which developed during bathing in the morning. Upon admission, neurological examination revealed right hemiparesis with ipsilateral limb ataxia and ipsilateral peri-oral and palmar dysesthesia. Based on neurological finding, he was diagnosed as having ataxic hemiparesis with ipsilateral cheiro-oral syndrome. Brain computed tomography and magnetic resonance imaging demonstrated a small lesion at the border between the posterior limb of the left internal capsule and the corona radiata, which was enhanced with gadolinium-DTPA administration. It has been reported that the disturbance of the cortico-pontine tract causes ataxic hemiparesis and that of the thalamo-cortical projection causes cheiro-oral syndrome. These findings of the present case, therefore, suggest that both of these pathways run closely together at the border between the posterior limb of the internal capsule and the corona radiata.

Ataxia↗
PubMed1993

Clinical features of recurrent embolization in acute cardioembolic stroke.

BACKGROUND AND PURPOSE: Recurrent embolization is a serious problem in acute cardioembolic stroke. However, the clinical features and predisposing factors of recurrent embolization have not been fully elucidated. METHODS: Subjects were 227 consecutive patients (128 men and 99 women, aged 68.6 +/- 13.2 years) with acute cardioembolic stroke who did not receive anticoagulant therapy during the first 14 days after stroke onset. We assigned the subjects to two groups according to the occurrence or nonoccurrence of recurrent attacks within 14 days of the stroke onset. We assessed their clinical features, coagulation study results, and underlying heart disease. RESULTS: Recurrent brain or systemic embolization during the first 14 days after onset was noted in 46 patients (20.3%, group A) but not in the other 181 (group B). Recurrent embolization was more frequently noted at an early phase than at a late phase during the initial 14 days. Mortality was higher in group A (19.6%) than in group B (8.8%). The mean plasma level of antithrombin III (77.8 +/- 19.5%) at admission in group A patients was significantly lower than that in group B patients (87.9 +/- 15.5%). After admission, hematocrit decreased in group B patients but slightly increased in group A patients, in whom diuretics were more commonly used. Rheumatic heart disease and prosthetic valves, in addition to the presence of intracardiac thrombi, were seen more commonly in group A patients, whereas atrial fibrillation without organic heart disease and myocardial infarction were more frequent in group B patients. CONCLUSIONS: Low plasma levels of antithrombin III, dehydration, the use of diuretics, and the presence of rheumatic heart disease, prosthetic valves, and intracardiac thrombi seem to be predisposing factors for recurrent embolization. Immediate anticoagulation may be considered in acute cardioembolic stroke patients if such predisposing factors are demonstrated.

Aged↗
PubMed1993

Distribution of atherosclerosis and risk factors in atherothrombotic occlusion.

BACKGROUND AND PURPOSE: The present study was performed to determine the relation between distribution of atherosclerosis and risk factors in Japanese patients with atherothrombotic occlusion. METHODS: We studied 154 patients with atherothrombotic occlusion of the extracranial internal carotid artery (n = 75, ICA group), the horizontal portion of the middle cerebral artery (n = 47, MCA group), and the basilar artery (n = 32, BA group), all of which were confirmed by cerebral angiography. We investigated the distribution of atherosclerosis of the three sites and compared the risk factors for atherosclerosis between the three groups. We used 113 subjects without stroke as the control group. RESULTS: A strong correlation was present between atherosclerosis of the extracranial internal carotid artery and that of the basilar artery. However, only a weak correlation existed between atherosclerosis of the middle cerebral artery and that of the other vessels. Although the prevalence of smoking and hypertension was higher and high density lipoprotein cholesterol levels were lower in the three groups than in the control subjects, no significant differences were found in age, sex, prevalence of smoking and hypertension, serum levels of triglycerides, and high density lipoprotein cholesterol among the three groups. The prevalence of coronary heart disease and diabetes mellitus and the serum levels of hemoglobin A1c, total cholesterol, and low density lipoprotein cholesterol were higher in the ICA and BA groups than in the MCA group. The prevalence of electrocardiographic evidence of left ventricular hypertrophy was higher in the MCA group than in the other groups. CONCLUSIONS: In addition to smoking, hypertension, and low concentration of high density lipoprotein cholesterol, diabetes mellitus and hypercholesterolemia seem to be associated with atherosclerosis of the extracranial internal carotid artery and the basilar artery, and advanced hypertension may play a role in the development of middle cerebral artery occlusion.

Adult↗
PubMed1993

Transesophageal echocardiography for detecting intracardiac thrombi in embolic stroke.

The authors studied 56 patients with cardioembolic stroke to search for intracardiac thrombi by use of transesophageal and transthoracic echocardiography. Forty consecutive patients were examined within four weeks of stroke onset and the remaining 16 in the chronic stage. They also performed ultrafast computed tomography in 9 of them. Underlying heart disease was present in all subjects. Anticoagulant therapy had already been started in 29 at the time of examinations. Using their own criteria for echocardiography, they diagnosed intracardiac thrombus in 7 cases and valvular vegetation in 1. Six thrombi were located in the left atrial appendage, 4 of which were smaller than 10 mm in diameter. These small thrombi were not found by either transthoracic echocardiography or computed tomography. Transesophageal echocardiography appears to be superior to the other two methods, especially for detecting small intracardiac thrombi in the left atrial appendage.

Adult↗