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Y Tokuriki

Publications and source records attributed to Y Tokuriki.

At least 19 recordsLinked to original sources
PubMed2001

Abnormal magnetization transfer ratios in normal-appearing white matter on conventional MR images of patients with occlusive cerebrovascular disease.

BACKGROUND AND PURPOSE: Chronic hypoperfusion may cause ischemic insult in the deep white matter. The magnetization transfer phenomenon is associated with the amount and constitution of myelin. The purpose of this study was to assess the usefulness of the magnetization transfer ratio (MTR) for detecting vasculometabolic abnormalities on positron emission tomography (PET) studies in patients with unilateral severe stenosis of the internal carotid artery (ICA). METHODS: MTR maps and PET data-including regional cerebral blood flow (rCBF), regional cerebral metabolic rate of oxygen (rCMRO(2)), and regional oxygen extraction fraction (rOEF)-were investigated in 13 patients with unilateral severe stenosis of the ICA. The same regions of interest were selected in the white matter both on MTR maps and PET scans. The areas were classified into three groups based on MTR values (group 0, MTR >47.22%; group 1, MTR = 45.77% to 47.22%; group 2, MTR <45.77%), and the relationship between MTR and PET data was analyzed by means of both absolute values and asymmetric index (AI). RESULTS: Abnormal values could not be detected in the areas classified as group 0. The areas classified as group 1 were characterized by absolutely normal values of rCMRO(2) and increased rOEF with AI, which was assessed as viable and reversible on the PET study. The areas classified as group 2 showed decreased rCMRO(2) with absolute values, which was considered irreversible in PET. A significant overall linear correlation was found between MTR and rCMRO(2) values. CONCLUSION: Using the MTR technique to classify ischemic damage into three groups (normal, reversible, and irreversible), we found a significant correlation between the reduction of MTR and that of rCMRO(2) in white matter with ICA stenosis. We believe that the MTR technique may partly replace PET data in the assessment of ischemic injury.

Aged↗
PubMed2000

Evaluation of brain metabolism in steno-occlusive carotid artery disease by proton MR spectroscopy: a correlative study with oxygen metabolism by PET.

UNLABELLED: Carotid occlusive diseases may cause ischemic changes in both the gray matter and the white matter as a result of hemodynamic compromise. To validate the use of proton magnetic resonance spectroscopy (MRS) in evaluating the carotid occlusive diseases, we compared changes in peaks of choline, in the sum of creatine and phosphocreatine, and in N-acetyl-aspartate (NAA) of the white matter with cortical oxygen metabolism measured by PET. METHODS: Eleven patients with unilateral steno-occlusive carotid artery disease underwent PET and MRS. Ten age-matched healthy volunteers underwent MRS. No subjects had cortical infarction. MRS was performed bilaterally in the centrum semiovale. Regional blood flow, regional metabolic rate of oxygen (rCMRO2), and regional oxygen extraction fraction (rOEF) of the cerebral cortex were measured by the steady-state method with 15O gas. RESULTS: The asymmetry index of the ratio of NAA to the sum of creatine and phosphocreatine (NAA/Cr) correlated positively with the asymmetry index of rCMRO2 (r = 0.77; P < 0.01). Because rCMRO2 is a marker of tissue viability, the NAA/Cr of the centrum semiovale may reflect viable neuronal cells. The asymmetry index of the ratio of choline to the sum of creatine and phosphocreatine (Cho/Cr) showed a significant positive correlation with the asymmetry index of rOEF (r = 0.65; P < 0.05). All but 1 patient with an increased Cho/Cr (>1.03) showed an increase in rOEF of the ipsilateral cortex (>0.56). This finding may indicate membrane damage caused by ischemia, because the centrum semiovale is the deep watershed zone. CONCLUSION: The metabolic changes in the centrum semiovale detected by proton MRS reflect a hemodynamically compromised state and are useful in evaluating tissue viability.

Aged↗
PubMed1998

[Treatment of tuberculous meningitis: marker of cure].

A 49-year-old male with tuberculous meningitis was reported. When admitted to our hospital with mild right hemiparesis, he was alert but he developed disorientation 7 days later. A diagnosis of tuberculous meningitis was reached because of elevated levels of adenosine-deaminase at 19.6U/liter in the cerebrospinal fluid. MRI showed a marked enhancement in the basal cisterns and an enhanced intraparenchymal lesion in the brainstem. Chronological changes of MRI findings did not closely correlate with the clinical course. Slight meningeal enhancement on MRI seems to remain for a long time without active tuberculous meningitis, and absence of the meningeal enhancement on MRI is not necessarily appropriate as a marker of cure of tuberculous meningitis.

Adenosine Deaminase↗
PubMed1998

[Predictability of EC/IC bypass function: a retrospective study].

Although the efficacy of extracranial/intracranial bypass for reduction of risk of ischemic stroke has been denied, we have encountered patients in whom bypass operation seems to have improved his or her clinical course. The efficacy of bypass should be evaluated not by the patency of the bypass but by the extent of collateral circulation brought about by the bypass. We retrospectively analyzed our patients to determine whether the extent of bypass flow could be predicted from the results of preoperative studies. In 18 hemispheres of 18 consecutive patients who underwent extracranial/intracranial bypass surgery, correlation between the extent of bypass flow and the multiple preoperative factors including the angiographic findings were investigated. The bypass function was highly predictable in the light of preoperative studies. In all of 10 hemispheres in patients under 70 years of age and with occlusive lesions in the proximal portion of the middle cerebral artery, collateral circulation through the bypass developed to an extensive or a moderate degree. In 9 of 10 hemispheres in which an interval between the latest attack and the diagnosis of hemodynamic failure was 4 weeks or longer, collateral circulation through the bypass was shown to have developed to an extensive or a moderate degree. Our results indicate that extensive or moderate collateral circulation through the bypass can be expected only in patients under 70 years of age, with lesions in the proximal portion of the middle cerebral artery, and in whom an interval between the latest attack and diagnosis of hemodynamic failure was 4 weeks or more.

Adult↗
PubMed1997

[Localization of the pyramidal tract in the internal capsule: relationship between CT classification of thalamic hemorrhage and motor weakness].

To better understand the pyramidal tract of the internal capsule, we evaluated the relationship between the localization of thalamic hemorrhage and motor weakness. On an axial CT scan at the level of the pineal body, two lines were drawn as follows: line-a between the lateral edge of the anterior horn and the lateral edge of the trigone, line-b vertical to the sagittal line and passing the midpoint of the third ventricle. The location of the hematoma was classified into three types according to localization of the center of the hematoma and lateral extension beyond line-a as follows: type A (anterior), type P (posterior) and type PL (postero-lateral). Discrepancy of motor weakness between upper extremities and lower extremities was higher in patients with hematoma of type P and type PL (p < 0.05) than in those with hematoma of type A. Improvement of motor weakness on discharge was higher in patients with type P (p < 0.01) than in those with type A. We concluded that most of the pyramidal tract fibers were located in the third quarter of the posterior limb of the internal capsule but a small number of pyramidal tract fibers were located in the anterior two-thirds of it. A greater number of cortico-spinal fibers to the upper extremities than to the lower extremities occupy the third quarter of the posterior limb of the internal capsule.

Adult↗
PubMed1995

Ruptured aneurysm of the distal posterior inferior cerebellar artery in a neonate--case report.

A 34-day-old male presented with a rare neonatal ruptured aneurysm of the distal posterior inferior cerebellar artery manifesting as a 10-day history of enlargement of head circumference. Magnetic resonance imaging revealed hydrocephalus and a round infratentorial enhanced lesion which compressed the medulla. Left vertebral angiography demonstrated an aneurysm on the telovelotonsillar segment of the left posterior inferior cerebellar artery. Ventriculoperitoneal shunt emplacement and proximal artery clipping were performed. The cerebrospinal fluid was bloody, suggesting aneurysm rupture had caused hydrocephalus. His postoperative course was uneventful, and neurological and developmental findings were normal 7 months later. Present neuroimaging, surgical, and neuro-anesthesiology techniques allow successful surgical intervention in cases of neonatal ruptured aneurysm.

Aneurysm, Ruptured↗
PubMed1995

[A case of successful acute revascularization using a long vein graft].

We experienced a case of successful acute revascularization using a long vein graft. A 68-year-old man was admitted to our department due to transient ischemic attack of the left hemiparesis. CT scan showed no infarction, but PAO-SPECT revealed moderate hypoperfusion in the right ACA and MCA area. Cerebral angiography demonstrated right IC occlusion at its origin and moderate collateral circulation via leptomeningeal anastomosis from the PCA area, and via the external carotid system, especially directly from STA. But the STA was very narrow. Three days after admission, left hemiparesis appeared again and deteriorated severely. This time the hemiparesis persisted. Although MRI demonstrated little infarction in the right frontal lobe, we decided to carry out revascularization on the same day. Right saphenous vein was harvested for a graft because of the narrow STA. The facial artery and angular artery was selected as a donor and a recipient respectively, to avoid a clamp of the EC and a craniotomy of the STA running area. Finally we performed a facial artery-vein graft-angular artery (M4) bypass. The patient showed no complication and the left hemiparesis improved enough to allow the patient to walk by himself. Revascularization using vein graft is dangerous for acute ischemia due to the possibility of a complication such as brain edema and hemorrhagic infarction. The usual style of vein graft bypass is an EC-vein graft-M2 or M3 bypass. Using this style, high pressure inside the EC is carried intracranially.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Recurrent malignant histiocytosis with cerebrospinal involvement--case report.

A 61-year-old male presented with recurrent malignant histiocytosis of the brain manifesting as nausea and headache. Malignant histiocytosis is a disorder of proliferating histiocytes characterized by a rapidly progressive and fatal course, but central nervous system involvement is relatively rare. Magnetic resonance (MR) imaging demonstrated cerebrospinal fluid (CSF) dissemination of histiocytes as a low-intensity area on the T1-weighted image with marked gadolinium-diethylenetriaminepenta-acetic acid enhancement and a high-intensity area on the T2-weighted image. CSF cytological examination revealed an increased level of atypical histiocytes. Brain and spine irradiation, and intrathecal methotrexate and prednisolone administration induced remission. MR imaging is particularly useful for the diagnosis of meningeal dissemination of malignant histiocytosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

In vivo study of flow pattern at human carotid bifurcation with regard to aneurysm development.

In order to investigate the developmental mechanism of cerebral aneurysms, the in vivo flow pattern around human cervical carotid bifurcations was studied by flow visualization using digital subtraction angiography with an isotonic contrast medium. The blood stream containing the medium impinged on the apex, then proceeded along the walls of the branches. After opacification of the whole lumen around the apex, most of the medium was carried away, while some remained for a few seconds at the carotid sinus. In the internal carotid artery, the blood struck the wall at an oblique angle near the tops of the arterial curvatures. In cases with atheromatous plaque or kinking of the branch, the blood passed through the stenosed segment and moved upstream, indicating turbulence. The study suggests that haemodynamic forces around the apex consist mainly of impingement on the apex and shear stress to the wall at and around the apex. In branches, high shear stress seems to exist. It might be possible that high shear stress causes degenerative changes in the endothelial layer, initiating the formation of saccular and fusiform cerebral aneurysms.

Adolescent↗
PubMed1988

[A case of chondroblastoma with intracranial extension].

A case of chondroblastoma with intracranial extension from middle cranial base is reported here. Chondroblastomas usually arise from the epiphysis of long bone. Intracranial chondroblastomas are very rare and only 14 cases have been reported. Histological feature of this tumor is to have numerous multinucleated giant cells resembling the giant-cell tumor. But this case has the typical features of chondroblastoma in the histological, immunohistochemical, and electron microscopical studies.

Adult↗
PubMed1986

Brainstem glioma: an analysis of 85 cases.

The study analyses 85 cases of brainstem glioma in the past 35 years, 69 of which include patients under 16 years of age. The incidence of brainstem glioma was 2.4% of all intracranial tumours, and 9.4% of intracranial tumours in children. There were two peaks in age distribution, in the first and in the fourth decades. In children, the tumours were located mainly in the pons, so VIth and VIIth cranial nerve palsies, and pyramidal and cerebellar signs were frequently seen. In adult cases, the tumours ranged in location from the midbrain to the medulla, so neurological symptoms caused by lesions of the whole brainstem axis were seen. The left side was dominant in both age groups. The choice of treatment was steroid administration and radiation. Chemotherapy was not effective. Even after these treatments, the median survival period from onset was no longer than 10.5 months. We conclude that the treatment of brainstem gliomas in children should be distinguished from adult cases, which in the latter may be considered to be merely one of the gliomas which may occur at any other sites. Since brainstem gliomas in children may be congenital, we must redirect our treatment of these lesions to treatment of congenital tumours.

Adolescent↗
PubMed1986

[Pharmacokinetics and toxicity of intrathecal administration of recombinant interleukin 2].

In order to contribute to the development of adoptive immunotherapy against malignant brain tumors, the pharmacokinetics and toxicity of intrathecally administered recombinant interleukin-2 in dogs and human patients were analyzed. The pharmacokinetics showed that a high concentration of IL-2 was maintained in the intrathecal cavity in both dogs and human (t1/2 = 1.41 and 1.68 hours, respectively) after administration. However, no activity of IL-2 was detected in the cerebrospinal fluid after the systemic administration of rIL-2 in one dog. No meningitis, ventriculitis or degeneration of neurons was seen histopathologically in dogs 3 weeks after the intrathecal administration of rIL-2 (200 units). A high concentration of IL-2 in the tumor cavity was maintained for a very long time (t1/2 = 14.8 hours) after the intratumoral administration of rIL-2 in one of the patients. Although low-grade fever and mild headache were sometimes observed after the intrathecal administration of rIL-2 in patients, there was no other side effect mentioned. Intrathecal or intratumoral administration of rIL-2 appeared to be an valuable procedure which should be evaluated in conjunction with adoptive immunotherapy against malignant brain tumors.

Adult↗
PubMed1985

Deep Sylvian meningiomas.

A case of deep Sylvian meningioma in a 35-year-old woman was precisely diagnosed preoperatively with the aid of computed tomography and stereoscopic cerebral angiography. On reviewing the literature, it appears to be the first case that has been accurately diagnosed preoperatively and successfully treated by a total excision without serious complication. We report this case in detail together with another, similar case which we had encountered previously.

Adult↗