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Dive into the research topics where Takamasa Mizuno is active.

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Featured researches published by Takamasa Mizuno.


Stroke | 2003

Effect on Cerebral Vasospasm of Coil Embolization Followed by Microcatheter Intrathecal Urokinase Infusion Into the Cisterna Magna A Prospective Randomized Study

Jun-ichiro Hamada; Yutaka Kai; Motohiro Morioka; Shigetoshi Yano; Takamasa Mizuno; Teruyuki Hirano; Kiyoshi Kazekawa; Yukitaka Ushio

Background and Purpose— Vasospasm remains the leading cause of death and permanent neurological disability in patients with aneurysmal subarachnoid hemorrhage (SAH). The objective of our prospective randomized trial of coil embolization followed by intrathecal urokinase infusion into the cisterna magna (ITUKI therapy) was to test its effectiveness in preventing or alleviating the severity of ischemic neurological deficits caused by vasospasm. Methods— We enrolled 110 patients with ruptured intracranial aneurysms eligible for coil embolization and randomly assigned them to embolization with (n=57) or without (n=53) ITUKI therapy performed within 24 hours of aneurysmal SAH. The incidence of symptomatic vasospasms and the clinical outcomes, based on the Glasgow Outcome Scale, 6 months after SAH onset were assessed. Results— There were no side effects or adverse reactions attributable to ITUKI therapy. Symptomatic vasospasm occurred in 5 patients (8.8%) with and 16 (30.2%) without ITUKI therapy; the difference was significant (P =0.012). Although the mortality rate did not differ between the groups, patients with ITUKI therapy had significantly better outcomes than those without (P =0.036). Conclusions— Our results demonstrate that ITUKI therapy significantly reduced the occurrence of symptomatic vasospasm. Although it did not completely prevent vasospasms, ITUKI therapy resulted in a lower rate of permanent neurological deficits.


Neuroradiology | 2005

Double microcatheter technique for endovascular coiling of wide-neck aneurysms using a new guiding device for the transcarotid approach: technical note.

Yutaka Kai; Jun-ichiro Hamada; Motohiro Morioka; Shigetoshi Yano; Takamasa Mizuno; Jun Ichi Kuratsu

In the endovascular treatment of cerebrovascular diseases, positioning the guiding catheter is of great importance. In cases where vessel tortuosity prohibits positioning the guiding catheter in the carotid artery via the femoral approach, we use a direct carotid approach via common carotid artery puncture. For direct puncture of the common carotid artery we devised a 6-Fr sheath with double insertion points. This new device facilitates the use of double microcatheters and provides safe and effective vascular access.


Neurosurgery | 2003

Surgical indications to maintain quality of life in elderly patients with ruptured intracranial aneurysms.

Shigetoshi Yano; Jun-ichiro Hamada; Yutaka Kai; Tatemi Todaka; Tsuyoshi Hara; Takamasa Mizuno; Motohiro Morioka; Yukitaka Ushio

OBJECTIVEWe performed a retrospective study to assess long-term outcomes in very old patients with ruptured intracranial aneurysms. The aim of the study was to develop guidelines for choosing surgical or conservative treatment with the goal of maintaining patients’ quality of life. METHODSBetween 1996 and 1999, 76 consecutive patients, aged 80 to 89 years, with ruptured intracranial aneurysms were treated at 18 participating centers. They were divided retrospectively into operated and nonoperated groups, and their preoperative characteristics and treatment outcomes were analyzed. Their Glasgow Outcome Scale and Barthel Index scores at least 2 years after the insult were recorded and analyzed from the perspective of their admission Hunt and Hess grade. RESULTSOur retrospective review encompassed 5.9 years. Of the original 76 patients, 54 (71.1%) died, 13 (17.1%) had a good outcome (Barthel Index ≥60), and 9 (11.8%) had a poor outcome (Barthel Index <60). All patients with Hunt and Hess grades of III or higher at admission had poor outcomes irrespective of treatment. Of 32 patients with an initial Hunt and Hess grade of I or II, 19 (59.4%) underwent surgery; 9 of these patients (47.4%) had good outcomes. Conversely, of 13 nonoperated patients (40.6%), only 2 (15.4%) experienced good outcomes. In seven of the nine operated patients with good outcomes, the aneurysm was small (<12 mm) and located at the internal carotid artery-posterior communicating artery junction. CONCLUSIONOur results suggest that patients in the 9th decade of life with ruptured intracranial aneurysms can be considered for surgical treatment if they have a Hunt and Hess grade of I or II. The highest rate of favorable results was achieved in patients with small internal carotid artery-posterior communicating artery aneurysms.


Acta Neurochirurgica | 2003

Endovascular coil trapping for ruptured vertebral artery dissecting aneurysms by using double microcatheters technique in the acute stage

Yutaka Kai; Junichirou Hamada; Motohiro Morioka; Tatemi Todaka; Takamasa Mizuno; Yukitaka Ushio

Summary¶Background. In the treatment of vertebral artery (VA) dissecting aneurysms, only proximal occlusion of the VA does not necessarily prevent rerupture. We evaluated the efficacy of coil trapping for the ruptured VA dissecting aneurysms using the double microcatheters technique. Methods. We treated 11 patients who presented with subarachnoid haemorrhage (SAH) due to rupture of a VA dissecting aneurysm which did not involve the posterior inferior cerebellar artery at the site of dissection. All patients tolerated the balloon occlusion test. Within 3 days of the SAH, the dissection site was trapped with a Guglielmi detachable coil (GDC) using the double microcatheters technique. The proximal and distal sites of the dissecting aneurysm were embolized simultaneously. Findings. GDC trapping at the affected site was successful in all 11 patients. Radiographic findings showed complete occlusion of the dissection site and patency of the unaffected artery. Although one patient experienced transient dysphagia, there were no major complications. Interpretation. The double microcatheters technique is effective for coil trapping of ruptured VA dissecting aneurysms in selected patients. The risks posed by this simple technique are minimal, even in the acute stage.


Stroke | 2000

Microcatheter Intrathecal Urokinase Infusion Into Cisterna Magna for Prevention of Cerebral Vasospasm Preliminary Report

Jun-ichiro Hamada; Takamasa Mizuno; Yutaka Kai; Motohiro Morioka; Yukitaka Ushio

Background and Purpose The feasibility of preventing vasospasm by intrathecal anterograde infusion of urokinase (UK) into the cisterna magna was studied in patients with recently ruptured aneurysms who had just undergone the placement of a Guglielmi detachable coil (GDC). Methods Immediately after complete embolization with the use of GDC-10 coils, 15 patients with Hunt and Hess neurological grades III and IV received 60 000 IU of UK in normal saline through a microcatheter advanced into the cisterna magna. UK infusion was repeated once or twice over a period of 2 to 3 days according to a decision based on CT evidence of a subarachnoid clot remaining in the cisterns. Before administering the last UK infusion, we obtained CT confirmation of almost complete clearance of clots in the basal cisterns. Results In all 15 patients, the microcatheter was advanced easily into the cisterna magna by use of the over-the-wire microcatheter technique. In 8 patients who received thrombolytic therapy within 24 hours of the ictus, there was almost complete clearance of the clot in the basal cisterns within 2 days of suffering the insult. When UK was injected at 24 to 48 hours after the insult, 7 patients manifested CT evidence of clearance at the latest 4 days after suffering the insult. In all 15 patients, CT scans obtained within 24 hours of the final UK administration showed complete resolution of clots in the basal cistern and almost complete resolution of clots in the basal interhemispheric fissure and bilateral proximal sylvian fissures. Although one patient developed a transient neurological deficit, no patients manifested permanent delayed neurological deficits as a result of vasospasm. Outcome assessment according to the Glasgow Outcome Scale, no less than 3 months after GDC placement, revealed good recovery in all patients, and none developed hydrocephalus requiring a shunt procedure. Conclusions In patients with recently ruptured aneurysms, GDC placement followed by immediate intrathecal administration of UK from the cisterna magna may be a safe and reasonable means of preventing vasospasms and may result in improved treatment outcomes.


American Journal of Neuroradiology | 2008

Intrathecal Urokinase Infusion Through a Microcatheter into the Cisterna Magna to Prevent Cerebral Vasospasm: Experimental Study in Dogs

Takamasa Mizuno; Jun-ichiro Hamada; Yutaka Kai; Tatemi Todaka; Motohiro Morioka; Yukitaka Ushio

BACKGROUND AND PURPOSE Our preliminary report on intrathecal urokinase (UK) infusion into the cisterna magna (CM) with a microcatheter showed good results in terms of vasospasm prevention in humans. In this study, we evaluated the relationship between different urokinase (UK) infusion sites and their effect on vasospasm prevention by using our canine subarachnoid hemorrhage (SAH) model. METHODS At 24 hours after SAH induction, we injected 1000 IU/kg UK into the cisterna magna (CM) or lumbar sac (LS) of dogs by using a microcatheter inserted at the lumbar region. We then obtained serial angiograms and chronologically examined the changes in the mean diameter of the basilar artery (BA) during a 14-day period to determine the effect of the different injection sites on vasospasm prevention. At 24 hours after UK injection, one dog from each group was killed for gross inspection of the subarachnoid clot. To measure its concentration in the CM and sylvian fissure, UK (1000 IU/kg) was injected into the CM or LS of dogs without SAH; measurements were taken at 15-minute intervals until 4 hours after injection. RESULTS At 24 hours after UK injection, subarachnoid clot in front of the brain stem persisted strongly in the LS group; it had almost disappeared in the CM group. In the LS group, there was severe and persistent BA constriction during the 14-day observation period. In the CM group, the BA was constricted on day 3; however, gradual dilatation occurred over time. The mean diameter of the BA on days 7, 10, and 14 was 48.2%, 53.9%, and 58.9% in the LS group and 62.6%, 70.5%, and 82.3% in the CM group. The difference between the two groups was significant on days 7, 10, and 14 (P <.05). In dogs without SAH, the average maximum UK concentration in the CM and the sylvian fissure was 2.5 and 6.7 times higher, respectively, in the CM group than in the LS group. CONCLUSIONS In our canine SAH model, the administration of UK into the CM was significantly more effective in preventing cerebral vasospasms than was administration into the LS.


Stroke | 2000

Microcatheter Intrathecal Urokinase Infusion Into Cisterna Magna for Prevention of Cerebral Vasospasm

Jun-ichiro Hamada; Takamasa Mizuno; Yutaka Kai; Motohiro Morioka; Yukitaka Ushio

Background and Purpose—The feasibility of preventing vasospasm by intrathecal anterograde infusion of urokinase (UK) into the cisterna magna was studied in patients with recently ruptured aneurysms who had just undergone the placement of a Guglielmi detachable coil (GDC). Methods—Immediately after complete embolization with the use of GDC-10 coils, 15 patients with Hunt and Hess neurological grades III and IV received 60 000 IU of UK in normal saline through a microcatheter advanced into the cisterna magna. UK infusion was repeated once or twice over a period of 2 to 3 days according to a decision based on CT evidence of a subarachnoid clot remaining in the cisterns. Before administering the last UK infusion, we obtained CT confirmation of almost complete clearance of clots in the basal cisterns. Results—In all 15 patients, the microcatheter was advanced easily into the cisterna magna by use of the over-the-wire microcatheter technique. In 8 patients who received thrombolytic therapy within 24 hours of th...


Acta Neurochirurgica | 2001

Transvenous Embolization for Vertebral Arteriovenous Fistula: Report of two Cases and Technical Notes

Yutaka Kai; Jun-ichiro Hamada; Takamasa Mizuno; Masato Kochi; Yukitaka Ushio; I. Kitano

Summary Background. Vertebral arteriovenous fistulas are relatively rare. Although the common treatment is transarterial embolization, it may be impossible to pass through the fistula (e.g. a microfistula created by a needle puncture). We report two patients with vertebral arteriovenous fistulas due to penetrating trauma who were successfully treated by transvenous embolization. Method. We present 2 patients with vertebral arteriovenous fistulas. One patient is presented to demonstrate complications following attempted internal jugular cannulation and the other is presented to demonstrate complications after surgery for a jugular foramen neurinoma. Both patients manifested the sign of a severe bruit. Findings. To identify the fistula point, simultaneous transarterial and transvenous angiography was performed. Using the transvenous approach, microcoils were applied to the fistula and the bruit completely disappeared. Interpretation. Transvenous embolization is a useful technique and a first-choice strategy to treat patients with the vertebral arteriovenous fistula due to penetrating trauma.


Surgical Neurology | 2003

Usefulness of multiple-site venous sampling in the treatment of adrenocorticotropic hormone-producing pituitary adenomas.

Yutaka Kai; Jun-ichiro Hamada; Toru Nishi; Motohiro Morioka; Takamasa Mizuno; Yukitaka Ushio

BACKGROUND While venous sampling for adrenocorticotropic hormone (ACTH) may be the most accurate way to establish a diagnosis of Cushings disease, its usefulness for lateralization of adenomas is limited even in combination with simultaneous bilateral sampling methods. Therefore, to increase accuracy in predicting the lateralization of adenomas, we performed a trial in which we carried out simultaneous venous sampling from multiple sites of the cavernous sinus (CS) and inferior petrosal sinus (IPS). Here we report on the usefulness of our method in the correct tumor lateralization in patients with Cushings disease. METHODS Eighteen patients with Cushings disease underwent simultaneous bilateral ACTH sampling. The samples were obtained from the anterior, middle, and posterior CS and the IPS. CS sampling after stimulation with corticotropin-releasing hormone (CRH) was also performed. The central-to-peripheral ACTH ratio (c/p ratio) was calculated using sampling data from each site; the lateralizing gradients (right versus left) were calculated using the c/p ratio. Instead of the conventional method where the lateralization gradient is based on sampling data from a single site, we used the distribution of the c/p ratio determined from multiple-site data. RESULTS There was no significant difference in the mean lateralization gradient obtained from each set of sampling data (p > 0.05). With the conventional method, correct tumor lateralization was obtained in 50% of tumors in the IPS; 72.2 to 77.8% of tumors in the CS; and 77.8% of tumors in the middle CS after CRH. Our method using ACTH contour analysis based on multiple sites produced correct results in all 18 of the patients examined. The difference in correct calls between the conventional method and our method was significant (p < 0.05). CONCLUSIONS Multiple-site sampling of ACTH is valuable for lateralizing the adenoma in patients with Cushings disease; it produces more correct results than does single venous sampling.


Journal of Clinical Neuroscience | 2018

A new type of hyperplastic anterior choroidal artery

Kazuma Doi; Takamasa Mizuno; Yoshinori Shigematsu; Osamu Kobayashi; Tatsuya Takezaki; Daisuke Muta; Toru Nishi

Hyperplastic anomaly of the anterior choroidal artery (hyperplastic AchA) and posterior communicating artery of duplicate origin (duplicated Pcom) are rare vessel anomalies. With some literature review, we here report three cases of hyperplastic AchA, one of which was considered a new type of hyperplastic AchA. This case was not categorized into Takahashi classification.

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