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Biomedical subjects

N Yoshimasu

Publications and source records attributed to N Yoshimasu.

At least 19 recordsLinked to original sources
PubMed2001

Factors in the natural history of chronic subdural hematomas that influence their postoperative recurrence.

OBJECT: Factors affecting the postoperative recurrence of chronic subdural hematomas (CSDHs) have not been sufficiently investigated. The authors have attempted to determine features of CSDHs that are associated with a high or low recurrence rate on the basis of the natural history of these lesions and their intracranial extension. METHODS: One hundred six patients (82 men and 24 women) harboring 126 CSDHs who were treated at Tokyo Kosei Nenkin Hospital between January 1989 and April 1998 were studied. Types of CSDHs were classified according to hematoma density and internal architecture, and the intracranial extension of the hematomas were investigated. The postoperative recurrence rate was calculated for each factor. Based on the internal architecture and density of each hematoma, the CSDHs were classified into four types, including homogeneous, laminar, separated, and trabecular types. The recurrence rate associated with the separated type was high, whereas that associated with the trabecular type was low. Chronic subdural hematomas are believed to develop initially as the homogeneous type, after which they sometimes progress to the laminar type. A mature CSDH is represented by the separated stage and the hematoma eventually passes through the trabecular stage during absorption. Based on the intracranial extension of each hematoma, CSDHs were classified into three types, including convexity, cranial base, and interhemispheric types. The recurrence rate of cranial base CSDHs was high and that of convexity CSDHs was low. CONCLUSIONS: Classification of CSDHs according to the internal architecture and intracranial extension may be useful for predicting the risk of postoperative recurrence.

Adult↗
PubMed2000

Relationship between drainage catheter location and postoperative recurrence of chronic subdural hematoma after burr-hole irrigation and closed-system drainage.

OBJECT: This study was conducted to determine the best position for the subdural drainage catheter to achieve a low recurrence rate after burr-hole irrigation and closed-system drainage of chronic subdural hematoma (CSDH). METHODS: The authors studied 63 patients with CSDH in whom the drainage catheter tip was randomly placed and precisely determined on postoperative computerized tomography (CT) scans and 104 patients with CSDH in whom CT scans were obtained 7 days postsurgery. The location of the subdural drainage catheter, the maximum postoperative width of the subdural space, and the percentage of the ipsilateral subdural space occupied by air postoperatively were determined and compared with the postoperative recurrence and reoperation rates. Patients with parietal or occipital drainage had a higher rate of CSDH recurrence and much more subdural air than those with frontal drainage. In addition, patients with residual subdural air demonstrated on CT scans obtained 7 days postsurgery also had a higher recurrence rate than those without subdural air collections. Furthermore, patients with a subdural space wider than 10 mm on CT scans obtained 7 days postsurgery had a higher recurrence rate than those with a space measuring 10 mm or less. CONCLUSIONS: The incidence of postoperative fluid reaccumulation seems to be reduced by placing the tip of the drainage catheter in the frontal convexity and by removing subdural air during or after surgery.

Adult↗
PubMed1997

Development and prevention of frozen shoulder after acute aneurysm surgery.

BACKGROUND: We conducted a study on periarthritis humeroscapularis or "frozen shoulder," a postoperative complication of aneurysm surgery. The purpose of this study was to seek the cause of this complication and the methods of preventing it in patients who undergo aneurysm surgery. METHODS: The diagnosis of frozen shoulder was based on the clinical presence of shoulder pain and difficulty in raising arms that developed within 3 months of surgery. Sixty-four patients who underwent aneurysm surgery with no motor deficit were examined and classified into three groups: (1) early surgery (29 patients in the acute stage after subarachnoid hemorrhage); (2) delayed surgery (19 patients in the chronic stage); and (3) elective surgery (16 patients with unruptured aneurysms). RESULTS: The incidence of frozen shoulder was 41% in the early surgery group, 16% in the delayed surgery group, and 13% in the elective surgery group. The highest incidence of frozen shoulder was found to occur in the early surgery group and was attributed to the immobility of their upper extremities during postoperative treatment. Since patients who undergo surgery in the acute stage are often delirious and confused for several days after surgery, their arms are tied down by their sides in order to prevent them from inadvertently removing catheters such as the one for ventricular drainage. It seems that this manner of immobilizing the patient's arms is the cause of the development of frozen shoulder: Our study showed that if each arm was passively raised by turns above the patient's shoulder, the patient was able to maintain the range of motion of the upper arms and was less likely to develop frozen shoulder. CONCLUSION: Inactivity of the shoulder joints due to immobilizing the upper extremities of patients after acute aneurysm surgery seemed to cause the development of frozen shoulder. The incidence of this complication was greatly reduced by keeping the patient's upper arms raised alternately to maintain their range of motion after acute aneurysm surgery.

Craniotomy↗
PubMed1997

[Rapidly enlarging supratentorial ependymoma in a child presenting initially with a small calcified lesion: case report].

The authors report an unusual case of a 11-year-old boy whose supratentorial ependymoma showed rapid growth. He had had generalized convulsive seizures when he was 9 years old. On an initial CT scan a small calcified lesion was identified adjacent to the right sensorimotor cortex. Repeated CT scans showed no interval change in the size of the tumor for 16 months. Then, he suffered an acute onset of left hemiparesis. The neuroimaging studies demonstrated a huge tumor with a large cyst in the right parietal region which had not been observed on CT scan 7 months before. Total removal of the tumor was performed and the histopathological diagnosis was ependymoma with no evidence of malignancy. However, MIB-1 staining of the specimen revealed a high index of 1 proliferative potential up to 25% in some area. The high score of MIB-1 staining correlated well with the rapid clinical course of this histologically benign ependymoma. The small calcified lesion demonstrated on the initial CT scan in this case is considered to have been a low grade ependymoma and to have abruptly transformed into a higher grade, one resulting in rapid enlargement. The authors stress that small intracranial calcified lesions should be carefully followed up by repeated neuroimaging studies at short intervals.

Calcinosis↗
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↗
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↗
PubMed1980

Primary Hodgkin's disease of the falx cerebri.

A case of the falx tumor of a 60-year-old man is reported. The tumor consisted of a pleomorphic mixture of lymphoid cells, histiocytes, atypical reticulum cells, and bizarre giant cells, including the diagnostic Reed-Sternberg cells. No transitional forms among these cells were observed. This is the first report of primary Hodgkin's disease of the dura matter, as verified by complete necropsy.

Autopsy↗
PubMed1980

Traumatic intracavernous aneurysm of the internal carotid artery following surgery for chronic sinusitis.

A case of traumatic intracavernous aneurysm is presented. The aneurysm at the siphon of the internal carotid artery was produced as a result of injury during an operation for chronic sinusitis. In addition to the formation of the aneurysm, the angiogram showed an irregular intimal dissection along the internal carotid artery distal to the aneurysm. To prevent disastrous bleeding from the aneurysm and further progression, a trapping operation was made in combination with a superficial temporal-middle cerebral artery anastomosis.

Carotid Artery Injuries↗
PubMed1976

[A case of brain cysticerosis].

A 59-year-old man was admitted to our hospital with the history of epileptick attack of six years' duration. The seizure was associated with Jacksonian march starting in the right hand and then generalized. Todd's paresis of the right arm followed occasionally to the seizure. He was admitted to neurosurgical unit of other hospital in 1968 and 1971, but on each occasion no tumor or vascular abnormality was detected by extensive examiniations such as brain angiography, pneumoencephalography or brain scanning. He continued his hob as an engineer with anticonvulsant. He once lived in Manchuria in 1930s and had history of pulmonary tuberculosis. He was suffering from diabetes mellitus and chronic otitis media. Recentry he developed headache, forgetfulness, speech disturbance and right hemiparesis and was admitted to our department through psychiatric unit. On examination he was fully conscious but showed typical Gerstmann's syndrome and conduction aphasia. He also revealed bilateral choked disc, right hemiparesis, right hemihypesthesia and right homonymous hemianopsia. The cerebral angiograms and peneumoencephalogram suggested a left parietal cystic tumor. Brain scan with technetium 99m was negative. The spinal fluid was clear but showed slight pleocytosis (99/3/ml). Leucocyte count in the peripheral blood was 6600 per cubic meter with eosinophils of 3%. On craniotomy, small white patches were scattered at the subarachnoidal space suggesting of history of some meningitis. In the left parietooccipital region at Brodmann's area 19, a greyish yellow transparent cystic tumor was found in the subarachnoidal space which was confirmed to be one of the multilocular grape-like cystic tumors extending from area 19, gyrus angularis towards the arcuate fasciculus without continuity with the left lateral ventricle. Microscopic examination showed the racemosal type of cysticercus but no scolex was found. The fluid of the cysts was similar to the spinal fluid. He is totally symptome-free after five months' lapse from the operation except for sporadic spikes on the electroencephalogram. Although some neurosurgeons are against direct operation of the cerebral cysticercosis, we are sure it is possible to cure these patients suffering from chronic cysticercosis with tumor-like symptoms i.e. the tumor type of Stepien. But it is essential not to rupture the cysts during the operative procedure to avoid dissemination of worms which might lead to acute severe cerebral edema. Besides, echinococcus cysts harbouring many worms are often hardly differenciated macroscopically from the cysts of cysticercosis.

Brain Diseases↗