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Biomedical subjects

H Segawa

Publications and source records attributed to H Segawa.

At least 109 records · Page 6Linked to original sources
PubMed1990

[A case of surgical excision of intracerebral cavernous angioma in a patient with thrombasthenia].

A case of thrombasthenia (Glanzmann) associated with an intracerebral cavernous angioma in a 32-year-old woman is reported. Since her childhood, the patient had experienced a tendency to develop purpura following minor trauma. But she had not had major bleeding even during pregnancy and delivery. On April 4, 1987, she presented generalized convulsion. A high density mass in the right temporal lobe was demonstrated with CT scan. Carotid angiogram was normal except that the right anterior choroidal artery was stretched. Inhomogeneous signal intensities in T1- and T2-weighted MRI images were seen in the tumor locus. The clinical diagnosis was cavernous angioma which was complicated with intracerebral hemorrhage. The patient had a disorder of platelet function without thrombocytopenia. Her bleeding time was markedly prolonged. Because of this, we did not try surgical excision at first. During the 13-month observation period, however, intracerebral bleeding occurred 5 times. We decided to operate on the patient using fresh blood and platelet transfusion. The postoperative course was uneventful and pathological diagnosis confirmed cavernous angioma. We would like to emphasize possible pitfalls in treating cases of intracerebral angioma with thrombasthenia.

Adult↗
PubMed1989

[A case of acute spinal epidural hematoma in a patient with antiplatelet therapy].

The authors report a case of acute spinal epidural hematoma occurring in a patient receiving antiplatelet drugs. A 76-year-old man with a history of cerebral infarction had been taking antiplatelet agents for one year. He suddenly developed severe back pain which woke him from sleep, and numbness of his lower extremities was then noted. He was hospitalized 15 hours later. Neurological examination revealed flaccid paralysis of both lower extremities with negative Babinski's reflex, and sensory disturbance below the level of L1. The bleeding time and prothrombin time were prolonged. Computed tomographic (CT) scan revealed a biconvex, relatively hyperdense mass in the posterior spinal canal at the level of T12. Metrizamide myelography disclosed an incomplete blockage caused by an epidural mass at the level of T11. Post-myelographic CT scan demonstrated a sharply demarcated extradural filling defect at the level of T11. Seventeen hours after the onset of symptoms, an emergency laminectomy was performed extending from T12 to L3, and the epidural clot was totally evacuated. Histological examination of the capsule of the hematoma revealed no vascular anomalies. The patient made a good postoperative recovery. To the authors' knowledge, this is the first reported case of spontaneous intraspinal hemorrhage in a patient taking antiplatelet drugs. Acute onset of persistent pain anywhere along the spinal axis and the development of spinal neurological deficits in a patient on antiplatelet therapy should raise the suspicion of a spinal epidural hematoma. It should be stressed that prompt neuroradiological diagnosis and rapid surgical decompression are essential to allow good recovery. The present case illustrates that neurological emergencies can occur in patients receiving antiplatelet therapy.

Acute Disease↗
PubMed1987

rCBF in brain tumours as measured by xenon enhanced CT.

Heretofore, the rCBF of brain tumours has been measured by the 133Xe clearance method, but the resolving power of this method is limited and flow values measured by this method correlate poorly with the anatomical structure. On the other hand, our xenon-enhanced method has several advantages over the conventional isotope method and enables us to evaluate rCBF with a resolving power of 4 mm. With this method, we evaluated rCBF in 15 brain tumour cases and obtained the following results: Mean rCBF value of the tumour is a little lower than that of grey matter and higher than that of white matter with oedematous change. The xenon-enhanced method enables us to distinguish the demarcation between the tumour area and the surrounding oedematous area and offers useful information for determining the extent of resection in surgery. Mean lambda value of the tumour which is not obtainable in vivo by radionuclide scanning, was 1.02 +/- 0.06 for gliomas and 0.72 +/- 0.09 for metastatic tumours.

Adult↗
PubMed1987

[Surgical indication for extracranial-intracranial arterial bypass determined by cerebral blood flow study and neurological function--a retrospective study].

In order to establish more strict and objective indication for EC-IC bypass, a retrospective study on the surgical effect on cerebral blood flow (CBF) and neurological function was carried out in 37 cases. STA-MCA bypass was carried out on 20 cases with IC occlusion and 17 cases with MCA occlusion. Twenty-two cases with completed stroke, 9 cases with TIA and 6 cases with RIND. All patients were able to ambulate before surgery, and none of them were hemiplegic. CBF study by 133Xe inhalation method was carried out before and 2 to 4 weeks after surgery. Bypass was patent in all cases. Thirty percent of all cases showed more than 16% increase in CBF (++ group) on the side of bypass surgery and another 30% demonstrated 6 to 15% increase (+). On the other hand 30% of cases appeared to be unchanged (+/-), and 10% showed more than 6% decrease (-). The less the pre-operative CBF value was, the more the post-operative CBF was expected to be increased. Patients with pre-operative CBF less than 60% of normal value (ISI = 63 +/- 4) showed remarkable increase (++), and those with 60 to 70% showed moderate increase (+). Contrarily, cases with more than 70% of normal value showed either no change or decrease. Neurological change was evaluated as to disappearance of TIA attack and improvement of hemiparesis or mental dysfunction. Seventy-seven percent of patients in groups with (++) and (+) effect on CBF showed improvement in neurological function, whereas only 27% of patients in groups with (+/-) and (-) effect demonstrated improvement, which was statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1986

[Efficacy of intracisternal papaverine on symptomatic vasospasm].

This study reports the effect of intracisternal administration of papaverine in 15 patients with vasospasm due to rupture of aneurysm. All patients had undergone clipping of aneurysm and had neurological deterioration and decreasing level of consciousness. Bolus injection of 40 mg of 1% papaverine hydrochloride was started on day 6.3 +/- 1.7 and continued for 4.4 +/- 1.6 days. In seven cases serial angiogram after initial dose revealed dilatation of IC and/or anterior, middle cerebral arteries at 30 min and further dilatation up to 85% increase in diameter at 60 min, which continued at least 90 min. Arteries with marked vasospasm responded more to papaverine than those with less vasospasm. There was a close correlation between degree of vasospasm and vasodilatation effect (r = 0.88, p less than 0.01). In all but two cases vasodilatation tended to become prominent by repeat doses, twice a day, for two to seven days (r = 0.87, p less than 0.01). Vasodilatation was observed only in IC and proximal trunks of ACA and MCA where papaverine could make direct contact, but not in the distal branches beyond A3 or M3. Neurological examination showed improvement of paresis or level of consciousness in 7 cases but no effect in 6 cases. Intracerebral hematoma occurred in two cases (one by high concentration 4% papaverine) during the treatment. Therefore intracisternal papaverine is the treatment of choice in cases with symptomatic vasospasm with some cautions on concentration to be administered.

Cerebral Angiography↗
PubMed1985

Dynamic computed tomography of the brain.

Dynamic computed tomography (CT) scanning was performed on five normal subjects, 38 patients with cerebrovascular disorder, and 20 patients with brain tumours. It consisted of performing six rapid sequential scans after intravenous bolus injection of iodinated contrast medium. By gamma variate fit technique, five features (corrected first moment, area, peak, time to peak, and per cent terminal height) were obtained from a time-density curve in a region of interest. We compared these features in one side of the brain with those in the corresponding contralateral side and tried to get information about cerebral perfusion. These results showed that by this technique we are able to detect arterial occlusions or Moya moya diseases non-invasively and know earlier and more clearly the re-establishment of circulation in the occluded arteries and of extravasation of contrast medium in ischaemic regions than by conventional CT scanning. In arteriovenous malformations, serial images of dynamic CT scanning demonstrated the anatomical details of the nidus, and the afferent and efferent vessels. We can also identify an exact extent of tumoral invasion of the brain in patients with malignant brain tumor.

Adult↗
PubMed1985

[Cerebral blood flow measured by Xenon enhanced CT in brain tumors].

In the management of malignant brain tumors, it is important to know the extent and viability of tumors. However, an ordinary CT scan with iodine enhancement has only a limited ability to distinguish the tumor from surrounding normal tissue. Since the blood flow in tumor tissue was found to be relatively high in a previous experimental report, we have investigated the blood flow in a tumor and the surrounding brain. The Xenon enhanced CT method has several advantages over the conventional isotope method and enables us to evaluate rCBF with the same resolving power as with the CT scan. We evaluated rCBF in 15 brain tumor cases and obtained the following results. Mean rCBF value of the tumor is a little lower than that of gray matter and higher than that of surrounding edema. Our Xe-CT method enables us to distinguish the demarcation between the tumor area and the surrounding edematous area and offers useful information for determining the extent of resection in surgery. Mean lambda value of the tumor which is not obtainable in vivo by radionuclide scanning, was 1.02 +/- 0.06 for gliomas and 0.72 +/- 0.09 for metastatic tumors. rCBF value and lambda value are important elements to know the uptake rate of anticancer drugs into the brain tumors. And to evaluate these value in each brain tumor is useful in the selection of chemotherapeutic agents.

Adult↗
PubMed1983

[Tomographic analysis of CBF in cerebral infarction].

Cerebral perfusion was examined in various types of occlusive disease by computed tomographic CBF method. The method utilized has several advantages over conventional studies using isotope, providing high resolution images in a direct relation to CT anatomy. Ten representative cases were presented from 25 consecutive cases of occlusive disease studied by this method. The method included inhalation of 40 to 60% xenon with serial CT scanning for 25 min. K (build-up rate), lambda (partition coefficient) and CBF values were calculated from HU for each pixel and Xe in expired air, based on Fick's principle, and displayed on CRT as K-, lambda- and CBF-map separately. CBF for gray matter of normal control was 82 +/- 11 ml/100 gm/min and that for white matter was 24 +/- 5 ml/100 gm/min. The ischemic threshold for gray matter appeared to be approximately 20 ml/100 gm/min, as blood flow in focus of complete infarction was below this level. Blood flow between 20-30 ml/100 gm/min caused some change on CT, such as localized atrophy, cortical thinning, loss of distinction between gray and white matter and decreased or increased density, which were considered to be compatible with pathological changes of laminar necrosis or gliosis with neuronal loss. In a case with occlusion of middle cerebral artery with subsequent recanalization, causing hemorrhagic infarct, hyperemia was observed in the infarcted cortex that was enhanced by iodine. Periventricular lucency observed in two cases, where blood flow was decreased below threshold, could be classified as "watershed infarction" mainly involving white matter. In moyamoya disease, blood flow in the anterior circulation was decreased near ischemic level, whereas that in basal ganglia and territory of posterior cerebral artery was fairly preserved, which was compatible with general angiographic finding of this disease.

Adult↗
PubMed1983

[Changes in CBF pattern after bypass surgery studied by CT with Xe enhancement].

UNLABELLED: Using a new method for rCBF measurement by serial CT scanning with non-radioactive xenon enhancement, CBF was measured before and/or after microsurgical anastomosis in five cases of focal cerebral ischemia. MATERIALS AND METHODS: Studies were carried out on 2 cases of MCA occlusion, 2 of IC occlusion, and 1 of "Moyamoya" disease. CBF was measured both before and after surgery in 4 cases, and the remaining case was measured after anastomosis. Pre-operative CBF was measured 1.4 +/- 0.5 months after the onset and post-operative CBF was 2 +/- 1 months after surgery. While 50 to 70% non-radioactive xenon was inhaled for 25 min and then discontinued, serial CT scanning was carried out every 3 min. K-map (clearance rate), lambda-map (partition coefficient), and CBF-map were displayed on CRT as images of each value. RESULTS: In all cases, initial pre-operative CBF decreased not only in the ipsilateral hemisphere, but also in the contralateral hemisphere. Especially in the major stroke cases, CBF reduction in the low density areas seen in CT was more than 75% of normal values. After microsurgical anastomosis, CBF increased in both hemispheres. In two cases of reversible ischemic attacks without any change in CT, the CBF markedly increased in central areas of ischemia and the CBF values became higher than normal value, that is hyperemia. On the contrary, in the central areas of the major stroke cases, that is, the low density areas in CT, CBF was still very low (under 25% of normal value) after anastomosis. However, in these cases, marked hyperemia was seen in the surrounding area of ischemic focus.

Adolescent↗
PubMed1982

[Computed tomographic measurement of regional cerebral blood flow by xenon enhancement (author's transl)].

The present study was conducted to overcome some of disadvantages of cerebral blood flow study by radionuclide, such as poor regionality of flow values and errors involved in pathological brains. Serial CT scanning was carried out during and after inhalation of 50 to 70% non-radioactive xenon in humans. Diffusible gas with high atomic number enhanced gray matter first 19 +/- 4 HU (mean +/- SD) on an average in Hounsfield unit (HU) and later white matter 24 +/- 4 HU. In seven normal subjects, blood flow in gray matter was 82 +/- 11 and that in white matter 24 +/- 5 ml/100 gm/min. Partition coefficient which is not readily obtainable by radionuclide study was 0.9 +/- 0.1 in normal gray matter and 1.4 +/- 0.2 in normal white matter. Two cases were presented to show k-map (clearance rate), lambda-map (partition coefficient) and CBF map, which displayed images of values calculated automatically, in black and white or color on CRT. The first case was a patient with metastatic brain tumor from lung in the left parietal region. The blood flow of the tumor was close to that of gray matter, whereas blood flow of edematous white matter surrounding the tumor was decreased to below 10 ml/100 g/min with partition coefficient ranged from 0 to 0.9. The second case was presented to demonstrate the resolution of the blood flow map obtained by this method. Multiple lacunar infarcts of the basal ganglia and white matter in the size of 1 to 3 mm, which were hardly identified on regular CT picture, were well visualized on CBF map. This method appeared to have several advantages over conventional isotope method and to provide useful clinical and research informations.

Aged↗
PubMed1982

[Evaluation of regional brain circulation by dynamic computer tomography].

Regional brain circulation was evaluated by dynamic computed tomography with iodine enhancement. The CT number (Hounsfield unit)-time curve provided us three parameters, namely, peak value, rapid washout ratio and filling time. It was indicated that these three parameters were related to different components. Peak value was related to blood volume, rapid washout ratio to transit time and filling time to filling velocity and/or distance from the point of injection to the site of measurement. In 10 patients with brain edema, both peak value and rapid washout ratio were decreased, comparing to these of 5 normal subjects. In 24 patients with cerebral infarction, decreased peak value was a main finding. In 3 patients with occlusion of internal carotid artery, delayed filling time was demonstrated in every patient. Clinical application of dynamic computed tomography was discussed.

Adult↗
PubMed1981

Role of platelets in vasogenic brain edema. I. Significance of thrombus formation in the damaged vessels.

In an investigation of the role of platelets in vasogenic edema in cats, direct observation of the cortex revealed that within several minutes after cold injury, platelet thrombi formed in small veins at the point where the veins emerged from the depths of the brain. Later, edema fluid extravasated from the veins at this same point. Pretreatment with a platelet inhibitor, RA-233, abolished the formation of platelet thrombi and remarkably enhanced the leakage of edema fluid. The microcirculation was assessed by carbon black perfusion and was found to fill better in the cats that received the platelet inhibitor. The better filling may be ascribed to a decreased number of thrombi and consequent improved blood flow in small blood vessels. We conclude that platelet aggregates play a major role in controlling the leakage of edema fluid after cold injury.

Animals↗
PubMed1981

Role of platelets in vasogenic brain edema. II. Contribution of platelet serotonin in brain edema.

In this study of the function of platelets after CNS injury, platelets were treated with serotonin labeled with radioactive carbon (14C) in animals subjected to a freezing lesion of the cerebrum. The distribution of platelet serotonin was measured by counting the specific activity of 14C-labeled serotonin in tissue and by autoradiography. Some of the animals were treated with RA-233, which inhibits the formation of platelet plugs after endothelial damage and the release of serotonin from platelets. Platelet serotonin accumulated near the surface of the cortex at the site of injury in all animals. More cerebral edema developed in animals treated with the platelet inhibitor than in untreated animals, probably because platelet aggregates were inhibited from forming and were not available to plug leaks in the traumatized vessels. Serotonin did not appear to facilitate the spread of edema.

Animals↗