S Kawada

Okayama University, Okayama, Okayama, Japan

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Publications (14)15.38 Total impact

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    ABSTRACT: Cellulose acetate polymer (CAP) solution is a new liquid embolic material, and it has been used clinically for the thrombosis of cerebral aneurysms. The purpose of the study was to test a method of aneurysm treatment. In an experimental model, retrievable interlocking detachable coils (IDCs) were used to create an intraaneurysmal frame or prop and then CAP was injected into 20 experimentally induced canine cervical aneurysms. Intraaneurysmal thrombosis was induced 1 week after aneurysm creation. Complete thrombosis was attempted in 12 aneurysms, and partial thrombosis was attempted in 4. Four other aneurysms served as controls. Follow-up angiography was performed for up to 8 weeks, and with the exception of 4 aneurysms, which were kept for a 2-year long-term follow-up study, the aneurysms were then harvested for histological examination. Thrombosis was successfully achieved in all cases except for 2 enlarged aneurysms that were initially partially thrombosed. No thromboembolism to distal vessels was observed. No compaction or shift of the CAP-IDC complex occurred even after 2 years. Histologically, CAP and IDCs conformed to the massive thrombotic complex without any fragmentation. By creating a frame or prop with retrievable microcoils, we were able to inject the CAP implies a comparison safely and precisely than has been previously reported. Our findings suggest that this method will be useful for the treatment of cerebral aneurysms.
    Acta medica Okayama 09/2000; 54(4):153-64. · 0.65 Impact Factor
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    ABSTRACT: Overdistention of vein grafts in arterial circulation and systemic hypertension are thought to be influential risk factors contributing to vein graft failures. This study tested the effects of external stenting in preventing systemic hypertension and overdistention of the rat vein graft in the long term. Jugular vein grafts were interposed into the carotid artery of normotensive (n = 39) and two-kidney, one-clip hypertensive (n = 30) rats. Jugular vein grafts wrapped with 1.5-mm-diameter polyester stents were used in normotensive (n = 26) and hypertensive (n = 25) rats. The vein grafts were harvested at 1, 2, 4, 8, 12, and 24 weeks after the grafting procedure. The neointimal area and wall thickness were measured by computerized planimetry, and Ki-67 immunohistochemistry was used to detect replicative smooth muscle cells in the graft wall. In each group, intimal hyperplasia was apparent at 1 week and increased gradually to 24 weeks. The number of Ki-67-positive cells was most increased at 2 weeks after the grafting procedure and gradually decreased thereafter. The numbers of Ki-67-positive cells and the extent of intimal hyperplasia were not significantly different between normotensive and hypertensive rats. Both neointima formation and cell proliferation in the graft wall were significantly reduced by external stenting as compared with the results with unstented grafts. Systemic hypertension by itself is not a risk factor for intimal hyperplasia and experimental vein graft failure in the long term. External stenting is effective against intimal hyperplasia, and it is possible to reduce the subsequent atherosclerotic change of the vein graft wall and improve the long-term patency of the vein graft with external stenting.
    Neurosurgery 05/2000; 46(4):963-9; discussion 969-70. · 2.53 Impact Factor
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    ABSTRACT: Atypical teratoid/rhabdoid tumor of the central nervous system in infancy and childhood was established as an entity based on histological, immunohistochemical, and cytogenetic studies. We report the case of a 7-month-old girl who presented with progressive paraplegia and hypesthesia of her legs. Imaging studies revealed a spinal cord mass occupying the entire spinal canal below the T(7) level. Through a T(12)-L(3) laminectomy, the intramedullary tumor was partially debulked. Histologically, the tumor specimen had rhabdoid cells, and immunostaining showed vimentin and cytokeratin positivity. No abnormality of chromosome 22q was detected with the fluorescence in situ hybridization method.
    Pediatric Neurosurgery 04/2000; 32(3):145-9. · 0.42 Impact Factor
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    ABSTRACT: A cellulose acetate polymer (CAP) solution was hypothesized to be useful for the embolization of arteriovenous malformations (AVMs). To investigate this possibility, we analyzed the clinical, radiological, and histological results of patients with AVMs embolized by using a CAP solution. We reviewed the cases of 11 patients with AVMs treated by embolization before surgical resection. We used two types of CAP solutions, CAP-M and CAP-L, which are mixtures of 250 mg of solid CAP and 1800 or 2250 mg of bismuth trioxide dissolved in 5.5 or 7.0 ml of dimethyl sulfoxide, respectively. After the embolization procedure, percent reduction of the nidus volume was measured, and thereafter, the clinical course and computed tomographic scans and/or magnetic resonance imaging scans were evaluated. All patients underwent surgical resection 1 to 51 days after embolization. Resected specimens were stained for light microscopic examination. Thirty-nine feeding vessels were embolized. The reduction rate of the nidus volume ranged from 20% to nearly 100%. Transient and persistent ischemic deficits occurred in three patients and one patient, respectively, and there were no hemorrhagic complications. All AVMs but one were completely resected by surgery. The embolized AVMs were soft enough to be easily cut and retracted. The histological examinations disclosed no or mild inflammatory reactions within 2 weeks after embolization. The internal elastic lamina was preserved in every case. Recanalization through the cast of the CAP mass was not observed until 51 days after embolization. CAP solution is a safe and useful embolic agent for AVMs.
    Neurosurgery 06/1999; 44(5):981-9; discussion 989-90. · 2.53 Impact Factor
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    ABSTRACT: This experimental study evaluated the effect of intrathecal injection of tissue-type plasminogen activator followed by cisternal drainage in the ultra-early stage of aneurysmal subarachnoid haemorrhage to prevent vasospasm. Twenty Japanese white rabbits were divided into five groups. Either tPA (groups A, B, and E) or saline (groups C and D) was injected intrathecally 1 hour (groups A, B, C, and D) or 21 hours (group E) after the intrathecal injection of blood. Cerebrospinal fluid was drained 2, 4, and 6 hours after the intrathecal injection of blood (groups A, C, and E). On day 4, the angiographic caliber of the basilar artery in each group was as follows (mean +/- SD): A, 85.9 +/- 5.0%; B, 74.6 +/- 5.3%; C, 69.1 +/- 2.7%; D, 64.0 +/- 4.9%; E, 80.2 +/- 2.7% (compared with baseline). In the two groups in which CSF was drained (groups A and C), fibrinolysis with tPA significantly suppressed vasospasm. In the two groups treated with tPA (groups A and B), cisternal drainage significantly suppressed vasospasm. In the two groups treated with saline (groups C and D), however, cisternal drainage did not suppress vasospasm. Examination of the series of CSF samples (groups A and C) showed that fibrinolysis with tPA effectively cleared clots early. In the two groups treated with tPA and CSF drainage (groups A and E), early removal of subarachnoid clots reduced the degree of vasospasm. Early fibrinolysis with tPA and early removal of subarachnoid clots by drainage is effective for preventing vasospasm.
    Acta Neurochirurgica 02/1999; 141(12):1331-8. · 1.55 Impact Factor
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    ABSTRACT: To test the usefulness of a cellulose acetate polymer(CAP) solution for brain arteriovenous malformations (AVMs), we analyzed the clinical and histological results of patients with AVMs embolized using CAP solution. We reviewed the cases of six patients with cerebral AVMs treated by embolization prior to surgical resection. We used two types of CAP solutions, CAP-M and CAP-L, which are mixtures of 250 mg of solid CAP and 1800 or 2250 mg of bismuth trioxide dissolved in 5.5 or 7.0 ml of dimethyl sulfoxide, respectively. All patients underwent surgical resection 1 to 37 days after the embolization procedure. Resected specimens were fixed in formalin and stained for light microscopic examination. Eighteen feeding vessels were embolized. The reduction rate of the nidus volume was between 20% and nearly 100%. Mild ischemic deficits occurred in one patients but there were no hemorrhagic complications related to the embolization procedures. All AVMs were completely resected by surgery. Direct inspection at surgery revealed that there was no apparent swelling or hematomas in the normal brain areas adjacent to the nidus, and the AVMs were soft enough to be easily retracted. The histological examinations disclosed no or mild inflammatory reactions within two weeks after embolization. The internal elastic lamina was preserved in every case. Recanalization of embolized vessels was not observed until 37 days after embolization. CAP solution is a safe and useful embolic agent for brain AVMs. Further study is needed to resolve the issue of recanalization.
    Interventional Neuroradiology 11/1998; 4 Suppl 1:117-20. · 0.77 Impact Factor
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    ABSTRACT: Various surgical procedures have been tried for patients with Moyamoya disease. The most effective treatment, however, is still controversial. We retrospectively evaluated the long-term results of 71 patients (26 men and 45 women) with Moyamoya disease surgically treated in our institute. They consisted of 56 pediatric patients (younger than 15 years) and 15 adult patients. Symptoms in all patients were due to cerebral ischemia. We did 123 operations on 119 hemispheres: 18 superficial temporal artery--middle cerebral artery (STA-MCA) anastomoses, six STA-MCA anastomoses with indirect bypass (IB), 41 encephalo-duro-arterio-synangiosis (EDAS), 29 encephalo-duro-arterio-myo-synangiosis (EDAMS) and 29 ribbon EDAMS. Average follow-up periods for each procedure were: 7 years for STA-MCA anastomosis, 6.2 years for STA-MCA anastomosis with indirect bypass, 11 years for EDAS, 5.6 years for EDAMS and 2.6 years for ribbon EDAMS, respectively. The results of each procedure were satisfactory because the preoperative transient ischemic attacks disappeared. Analysis of follow-up angiograms shows excellent filling of the ACA and MCA territory in the patients undergoing ribbon EDAMS. However, long-term follow-up study shows that about 10% of the patients had severe difficulty in social or school life because of intellectual impairment.
    Clinical Neurology and Neurosurgery 11/1997; 99 Suppl 2:S156-61. · 1.23 Impact Factor
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    ABSTRACT: Although a number of cases of unilateral Moyamoya disease have been reported, the natural history of this disease remains unclear. The clinical features of 17 patients initially diagnosed with unilateral Moyamoya disease at our hospital are reported. Age at onset was 3-45 years (mean, 13.5). Of these 12 cases had onset of symptoms in childhood and five had onset in adulthood. Seven were male and 10 were female. An ischemic attack was the initial episode in ten of the 12 pediatric cases, two of the five adult cases presented with intraventricular hemorrhage. Of the 12 pediatric patients six developed contralateral lesions between 4 and 34 months (mean, 20) after the diagnosis of a unilateral lesion. The remaining six pediatric patients and all adult patients did not develop lesions on the normal side. The mean age at onset for patients later developing contralateral lesions was 6.2 years. The pediatric cases remaining unilateral was 7.7 years. The normal hemisphere of three of the pediatric patients has remained unchanged on repeated follow-up angiograms for over 10 years. Young children tended to develop the vascular pathology bilaterally. However, there were some pediatric cases whose normal or atypical sides remained unchanged without development of bilateral lesions.
    Clinical Neurology and Neurosurgery 11/1997; 99 Suppl 2:S178-81. · 1.23 Impact Factor
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    ABSTRACT: We have reported improvement in the outcome of the younger patients with aneurysmal subarachnoid hemorrhage in the preceding article. The purpose of this article is to study if the same management protocol has simultaneously benefited the elderly patients. One hundred twenty-nine patients with aneurysmal subarachnoid hemorrhage, over 70 years old, who were consecutively admitted to Kagawa Prefectural Central Hospital from July 1972 to December 1992, were reviewed. Patient grouping and outcome evaluation were the same as those of younger patients. Changes in treatment protocol in this period, which were similar to those of the younger counterparts, resulted in an increased number of patients who actually underwent aneurysm clipping. Although the outcome evaluated at 6 months after initial hemorrhage was significantly poorer than that of the younger counterparts, there have been some improvements during the study period. Patients in good clinical condition at 6 months' follow-up (Glasgow Outcome Scale: Good Recovery) increased from 37.5% to 42.9% in grades I-II and from 0% to 23.1% in grade III, respectively. The improvement in the outcome of elderly patients was less remarkable than that observed in younger patients. Significantly higher incidence of preoperative rebleeding and postoperative symptomatic vasospasm has proven to be the major cause of mortality and major morbidity at present. More careful and sophisticated perioperative care is required in elderly patients with aneurysmal subarachnoid hemorrhage.
    Surgical Neurology 01/1996; 44(6):528-33. · 1.67 Impact Factor
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    ABSTRACT: This study was carried out to clarify if there has been any improvement in the outcome of patients with aneurysmal subarachnoid hemorrhage during the past 20 years. Because elderly patients have apparently poorer prognoses than younger patients, patients older than 70 years were analyzed separately in the following article. Five hundred seventy-one patients with aneurysmal subarachnoid hemorrhage, under 70 years, who were consecutively admitted to Kagawa Prefectural Central Hospital from July 1972 to December 1992, were reviewed. These patients were divided into four groups according to the time of admission. The ultimate outcome was evaluated by means of Glasgow Outcome Scale 6 months after the ictus. Changes in treatment protocol in this period included the induction of early surgery and the invention of a variety of modalities for the treatment of cerebral vasospasm. This resulted in a distinct increase in patients who actually underwent direct aneurysm clipping. Outcome has been significantly improved during this period, especially in patients with Hunt and Kosnik grade III (p<0.05, chi2). Patients in good clinical condition at follow-up (Glasgow Outcome Scale: good recovery) increased from 8.7% to 60.7%. Mortality decreased from 28.7% to 10.7%. Current therapeutic modalities have significantly improved the outcome of patients with aneurysmal subarachnoid hemorrhage. Rebleeding before early surgery remains as a major cause of unfavorable outcome and further progress on this subject is mandatory.
    Surgical Neurology 12/1995; 44(6):522-7. · 1.67 Impact Factor
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    ABSTRACT: The effect of cisternal drainage and intrathecal urokinase injection in preventing symptomatic vasospasm (SVS) after aneurysmal subarachnoid hemorrhage was studied in 60 patients with uniform background (Hunt & Kosnik grade III, younger than 70 yrs, undergoing surgery within 72 hrs after hemorrhage). The incidence of permanent neurological deficits caused by vasospasm was 5/16 without cisternal drainage, 5/34 with drainage alone, and 1/10 with drainage and urokinase injection. Analysis of patients without postoperative cisternal drainage showed the amount of subarachnoid clot on the initial computed tomographic scan was closely related to the occurrence of SVS (p < 0.05, unpaired t test). Analysis of patients with cisternal drainage showed the amount of bloody cerebrospinal fluid (CSF) drained during the 10 days after surgery and the duration of drainage placement were critical in preventing vasospasm (p < 0.05, unpaired t test). Greater CSF drainage significantly reduced the incidence of permanent neurological deficits caused by vasospasm (p < 0.01, chi 2), but significantly increased the incidence of hydrocephalus requiring shunt procedures (p < 0.01, chi 2). Urokinase injection via cisternal drainage achieved a further reduction in the occurrence of SVS. Intrathecal thrombolytic therapy after aneurysmal surgery is an effective method for SVS prophylaxis, and CSF drainage (> 1500 ml for 10 days) enhances the effect.
    Neurologia medico-chirurgica 10/1995; 35(10):732-6. · 0.49 Impact Factor
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    ABSTRACT: The Wechsler Adult Intelligence Scale and Yatabe-Guilford personality test were administered to 123 patients hospitalized for head injury who had made a relatively good recovery. Intelligence quotient (IQ) was correlated with clinical condition based on the Glasgow Coma Scale and duration of coma. More severely injured patients tended to show a greater decline in IQ. The type of lesion, as described by computed tomography, was also an important factor in predicting the outcome of intellectual function. The mean IQ of patients with diffuse injury, such as diffuse axonal injury and diffuse brain swelling, and intracerebral hematoma, was significantly lower than that of the control subjects, especially performance IQ (PIQ). Several patients demonstrated improved IQ level during the initial year. In particular, PIQ improved more than verbal IQ. The difference between the IQ of patients achieving social recovery and not was significant (p < 0.001). Causes of difficulty in returning to previous work were decreased IQ and personality change, such as lack of cooperativeness. Neuropsychological evaluation is important in predicting social recovery and selecting necessary neuropsychological rehabilitation.
    Neurologia medico-chirurgica 12/1993; 33(12):824-9. · 0.49 Impact Factor
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    ABSTRACT: Wechsler Intelligence Scale for Children-Revised (WISC-R) and Yatabe-Guilford personality test were administered to 31 children who had been hospitalized for head injury and made a GR or MD by the Glasgow Outcome Scale (GOS). The type of lesion, as defined by CT scan categories, was an important factor to prognosticate the outcome of intellectual function. The IQ, especially performance IQ, of acute subdural hematoma (EDH) or severe diffuse brain injury (DBI) was lower than that caused by other types of lesion. Several children demonstrated improvement in IQ level during the initial year. The difference between the IQ of the children who could return to previous school life and that of the children who could not was significant. One of the causes of difficulty in returning to previous school life is decreasing IQ and personality change such as social disadaptability. Neuropsychological evaluation is important in predicting school recovery and deciding proper neuropsychological rehabilitation.
    No shinkei geka. Neurological surgery 11/1993; 21(10):915-20. · 0.13 Impact Factor
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    ABSTRACT: A case of choroid plexus papilloma (CPP) associated with overproduction of cerebrospinal fluid (CSF) in an infant is reported. The tumor was totally resected. Histologically, it was diagnosed as CPP with several mitosis, however, there were no other features indicating malignancy. Transthyretin immunoreactivity was found in the tumor cells on CSF cytological examination as well as in surgical specimens. Though the percentage of PCNA was high (10.8%), it was not higher than other benign CPPs (mean score: 18.2%). There was no recurrence or dissemination on follow-up CT or MRI 1 year after surgery. The patient has grown normally after surgery without a shunting procedure.
    Nōshuyō byōri = Brain tumor pathology 02/1993; 10(1):81-6.

Publication Stats

132 Citations
15.38 Total Impact Points

Institutions

  • 1998–2000
    • Okayama University
      • Department of Neurological Surgery
      Okayama, Okayama, Japan
  • 1995–1996
    • Kagawa Prefectural Central Hospital
      Takamatu, Kagawa, Japan