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Dive into the research topics where Toshiaki Osato is active.

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Featured researches published by Toshiaki Osato.


Stroke | 2016

Significance of the Hemorrhagic Site for Recurrent Bleeding: Prespecified Analysis in the Japan Adult Moyamoya Trial

Jun C. Takahashi; Takeshi Funaki; Kiyohiro Houkin; Tooru Inoue; Kuniaki Ogasawara; Jyoji Nakagawara; Satoshi Kuroda; Keisuke Yamada; Susumu Miyamoto; Takashi Yoshimoto; Nobuo Hashimoto; Ichiro Tsuji; Yasutake Tomata; Tsuguya Fukui; Yasushi Okada; Masayasu Matsumoto; Yasuo Fukuuchi; Takashi Ohmoto; Yasuo Kuwabara; Izumi Nagata; Junichi Ono; Toshio Machida; Ryuji Sakakibara; Kanji Yamane; Shinji Okita; Kiyoshi Kumano; Toru Iwama; Yasuhiko Kaku; Nobuhito Saito; Hidenao Fukuyama

Background and Purpose— The primary results of the Japan Adult Moyamoya Trial revealed the statistically marginal superiority of bypass surgery over medical treatment alone in preventing rebleeding in moyamoya disease. The purpose of this analysis is to test the prespecified subgroup hypothesis that the natural course and surgical effects vary depending on the hemorrhagic site at onset. Methods— The hemorrhagic site, classified as either anterior or posterior, was the only stratifying variable for randomization. Statistical analyses were focused on the assessment of effect modification according to the hemorrhagic site and were based on tests of interaction. Results— Of 42 surgically treated patients, 24 were classified as anterior hemorrhage and 18 as posterior hemorrhage; of 38 medically treated patients, 21 were classified as anterior and 17 as posterior. The hazard ratio of the primary end points (all adverse events) for the surgical group relative to the nonsurgical group was 0.07 (95% confidence interval, 0.01–0.55) for the posterior group, as compared with 1.62 (95% confidence interval, 0.39–6.79) for the anterior group (P=0.013 for interaction). Analysis within the nonsurgical group revealed that the incidence of the primary end point was significantly higher in the posterior group than in the anterior group (17.1% per year versus 3.0% per year; hazard ratio, 5.83; 95% confidence interval, 1.60–21.27). Conclusions— Careful interpretation of the results suggests that patients with posterior hemorrhage are at higher risk of rebleeding and accrue greater benefit from surgery, subject to verification in further studies. Clinical Trial Registration— URL: http://www.umin.ac.jp/ctr/index.htm. Unique identifier: C000000166.


Cerebrovascular Diseases Extra | 2013

Initial ‘TTP Map-Defect’ of Computed Tomography Perfusion as a Predictor of Hemorrhagic Transformation of Acute Ischemic Stroke

Mizuya Shinoyama; Jyoji Nakagawara; Hiroshi Yoneda; Michiyasu Suzuki; Hidetoshi Ono; Ichiro Kunitsugu; Kenji Kamiyama; Toshiaki Osato; Hirohiko Nakamura

Background: Hemorrhagic transformation (HT) following acute ischemic stroke is a major problem, especially for the indication of reperfusion therapy including intravenous administration of recombinant tissue plasminogen activator (IV rt-PA). The specific predictive factors of HT have not yet been established. The present study evaluated the findings of computed tomography perfusion (CTP) images as predictors of subsequent HT to identify patients with low HT risk for reperfusion therapy such as IV rt-PA. Methods: We retrospectively reviewed 68 consecutive stroke patients (41 males; mean age 72.9 years) with steno-occlusive lesions in the major trunk, including 10 patients who underwent IV rt-PA. Each HT was detected on a follow-up T2*-weighted magnetic resonance image until 2 weeks after stroke onset and categorized into four groups [hemorrhagic infarction (HI) type 1 and 2, and parenchymal hematoma (PH) type 1 and 2] according to the European Cooperative Acute Stroke Study (ECASS) classification. We assessed clinical features and radiological findings between the HT and non-HT groups or the PH2 and non-PH2 groups. The efficacy of initial time to peak (TTP) mapping of CTP for predicting HT or PH2 was evaluated. Results: Thirty-four patients (50%) developed subsequent HT: 18 (52.9%) had HI and 16 (47.1%) had PH, including 9 PH2 patients (13.2%). IV rt-PA was not significantly associated with HT or PH2 occurrence. Forty of the 68 patients (59%) revealed defect areas on the initial TTP mapping (TTP map-defect), and 34 of these 40 patients (85%) developed secondary HT and 9 patients (22.5%) developed PH2. Initial ‘TTP map-defect’ was significantly associated with the occurrence of HT (p < 0.0001) and PH2 (p = 0.0070). Thirty of the 34 patients (88.2%) in the HT group experienced delayed recanalization of the occluded vessels, in contrast to only 8 of the 34 patients (23.6%) in the non-HT group. All patients of the PH2 group showed recanalization (p = 0.0042). In 40 ‘TTP map-defect’-positive patients, delayed recanalization was associated with the occurrence of HT (p < 0.0001) and PH2 (p = 0.0491). All 28 patients without ‘TTP map-defect’ did not develop HT, including 8 patients (28.6%) with delayed recanalization. Conclusions: Initial ‘TTP map-defect’ of CTP could accurately predict HT risk including PH2 risk and identify low-risk patients even in the delayed period.


Journal of Stroke & Cerebrovascular Diseases | 2012

Development of Transdural Anastomosis After Craniotomy in a Patient with Atherothrombotic Carotid Occlusion

Hideki Endo; Jyoji Nakagawara; Noriyoshi Okamoto; Toshiaki Osato; Kenji Kamiyama; Hirohiko Nakamura

Development of transdural anastomosis is extremely rare in the patients with atherosclerotic cerebrovascular disease. We report a rare case of development of transdural anastomosis after craniotomy in the patient with atherothrombotic carotid occlusion.


Archive | 2017

Secondary Prevention of Stroke with Atrial Fibrillation by New Oral Anticoagulants

Kenji Kamiyama; Toshiaki Osato; Hirohiko Nakamura

We used the results of secondary prevention analyses for patients with a history of stroke or TIA in the large-scale RE-LY, ROCKET-AF (J-ROCKET-AF), and ARISTOTLE clinical trials to investigate the choice of new oral anticoagulants (NOACs) to prevent recurrent stroke. In light of these results, we concluded that dabigatran 150 mg BID should be the first-choice treatment for comparatively young patients with no apparent renal dysfunction, and apixaban for other patients, and that their efficacy and safety can be broadly guaranteed.


Archive | 2006

Treatment Results of Poor-grade (WFNS Grade V) Patients with Subarachnoid Hemorrhage

Takehiko Sasaki; Joji Nakagawara; Toshiaki Osato; Kazuyuki Hayase; Rihei Takeda; Hirohiko Nakamura

Although surgical treatment of poor-grade patients with ruptured cerebral aneurysms is still challenging, it is well known that some patients become independent after surgical intervention. Controversy is how to select patients with factors predictive of favorable outcome. The purpose of this paper is to extract factors predictive of favorable or poor outcome from analysis of our treatment results.


Stroke | 2014

Effects of Extracranial–Intracranial Bypass for Patients With Hemorrhagic Moyamoya Disease Results of the Japan Adult Moyamoya Trial

Susumu Miyamoto; Takashi Yoshimoto; Nobuo Hashimoto; Yasushi Okada; Ichiro Tsuji; Teiji Tominaga; Jyoji Nakagawara; Jun Takahashi; Keisuke Yamada; Yasutake Tomata; Tsuguya Fukui; Yasuo Fukuuchi; Takashi Ohmoto; Yasuo Kuwabara; Izumi Nagata; Junichi Ono; Toshio Machida; Ryuji Sakakibara; Kanji Yamane; Shinji Okita; Toru Iwama; Yasuhiko Kaku; Nobuhito Saito; Hidenao Fukuyama; Kiyohiro Houkin; Satoshi Kuroda; Ichiro Yabe; Fumio Moriwaka; Akira Ogawa; Kuniaki Ogasawara


Neurologia Medico-chirurgica | 2012

Diagnostic imaging of higher brain dysfunction in patients with adult moyamoya disease using statistical imaging analysis for [123I]iomazenil single photon emission computed tomography.

Jyoji Nakagawara; Toshiaki Osato; Kenji Kamiyama; Kaori Honjo; Hironori Sugio; Kentarou Fumoto; Takeo Murahashi; Hidekazu Takada; Toshiichi Watanabe; Hirohiko Nakamura


Surgery for Cerebral Stroke | 2011

Transformation of the Vasa Vasorum from Normal Vessel Structures to Atheroma Nutrient Vessels on ICG Angiography of Cervical Carotid Artery Stenosis

Kenji Kamiyama; Jyoji Nakagawara; Hidekazu Takada; Kentaro Fumoto; Toshiaki Osato; Hirohiko Nakamura


Surgery for Cerebral Stroke | 2005

Treatment Results of Surgical Clipping or Endosaccular Coil Embolization in Patients with Ruptured Cerebral Aneurysms

Takehiko Sasaki; Toshio Hyogo; Taketo Kataoka; Toshiaki Osato; Kazuyuki Hayase; Jyoji Nakagawara; Hirohiko Nakamura


Surgery for Cerebral Stroke | 2003

Technique for Sylvian Fissure Opening on Pterional Approach: Dissection with the Reverse Plane View of Arachnoid Membrane.

Toshiaki Osato; Takehiko Sasaki; Kazuyuki Hayase; Hidekazu Takada; Satoru Mitsumasu; Hideto Yoshida; Makoto Senoo; Rihei Takeda; Hirohiko Nakamura

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Kenji Kamiyama

Memorial Hospital of South Bend

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Jyoji Nakagawara

Memorial Hospital of South Bend

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Takehiko Sasaki

Memorial Hospital of South Bend

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Kazuyuki Hayase

Memorial Hospital of South Bend

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Toshiichi Watanabe

Memorial Hospital of South Bend

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Taketo Kataoka

Memorial Hospital of South Bend

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Hidekazu Takada

Memorial Hospital of South Bend

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Hideki Endo

Memorial Hospital of South Bend

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