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Featured researches published by Yasunobu Nakai.


Surgical Neurology | 2000

Distal superior cerebellar artery aneurysm in a patient with systemic lupus erythematosus: Case report

Yasunobu Nakai; Akio Hyodo; Kiyoyuki Yanaka; Hiroyoshi Akutsu; Tadao Nose

BACKGROUND The authors describe a case of ruptured distal superior cerebellar artery (SCA) aneurysm in a patient with systemic lupus erythematosus (SLE). CASE DESCRIPTION A 31-year-old female who had been treated for SLE for 13 years presented with a subarachnoid hemorrhage. Cerebral angiography demonstrated an aneurysm arising from the cisternal portion of the left superior cerebellar artery. The patient underwent early endovascular coil embolization and was discharged from our hospital without neurological deficit. CONCLUSION Aneurysms arising from peripheral segments of cerebellar arteries are rare, and delayed surgical clipping has been recommended for these lesions. In addition, the outcomes of SLE patients with ruptured cerebral aneurysms are reported to be very poor due to the systemic complications of SLE. However, our patient had a favorable outcome with early endovascular treatment for the ruptured aneurysm and with appropriate medical treatment for the accompanying SLE. Therefore, early endovascular coil embolization is worthy of consideration among the options for therapeutic intervention in these conditions.


Journal of Clinical Neuroscience | 2002

Fatal cerebral infarction after intraventricular hemorrhage in a pregnant patient with moyamoya disease

Yasunobu Nakai; Akio Hyodo; Kiyoyuki Yanaka; Tadao Nose

Moyamoya disease is a progressive occlusive cerebrovascular disorder of unknown etiology. We describe a case of a fatal cerebral infarction after intraventricular hemorrhage in a 29-year-old primipara with moyamoya disease. The patient had been stable for about 10 days after the initial hemorrhage, but she showed a fulminant clinical course of cerebral infarction, and died on the 16th day after the initial hemorrhage. Abnormality in coagulation system and/or cerebral vasospasm may have resulted in such a fulminant clinical course. A possible pathogenesis of this rare condition is discussed.


Journal of Computer Assisted Tomography | 2012

Moyamoya disease: evaluation of postoperative revascularization using multiphase selective arterial spin labeling MRI.

Tsukasa Saida; Tomohiko Masumoto; Yasunobu Nakai; Masanari Shiigai; Akira Matsumura; Manabu Minami

Purpose The purpose of this study was to evaluate cerebral blood flow through the bypass in operated patients with Moyamoya disease using multiphase selective arterial spin labeling (ASL) technique. Materials and Methods Fifteen surgically treated cerebral hemispheres from 11 patients with Moyamoya disease were included. Selective ASL examinations were performed during the early postoperative period (mean, 5.5 days) on 4 hemispheres and late postoperative period (mean, 332.7 days) on 15 hemispheres. The labeling slab was positioned at the bypassed external carotid artery and 5 slices in each of the 10 sequential phases were acquired using a 3-T scanner. Results Two of 4 early postoperative ASL examinations and all late postoperative ASL examinations demonstrated blood flow through the bypass. The remaining 2 early postoperative ASL examinations showed absence of blood flow; however, blood flow improved on follow-up examinations. Conclusion Multiphase selective ASL technique can provide information about the dynamics of postoperative blood flow through the bypass in Moyamoya disease.


World Neurosurgery | 2011

Time-Course Analysis of Brain Perfusion Single Photon Emission Computed Tomography Using a Three-Dimensional Stereotactic Region-of-Interest Template in Patients with Moyamoya Disease

Aiki Marushima; Hideo Tsurushima; Kensuke Suzuki; Yasunobu Nakai; Hirofumi Nemoto; Akira Matsumura

OBJECTIVE To verify the usefulness of the time-course analysis of regional cerebral blood flow (CBF) and cerebrovascular reserve (CVR) estimated quantitatively using the three-dimensional stereotactic region-of-interest template (3DSRT) to assess clinical status in patients with moyamoya disease. METHODS The study comprised 12 patients (5 men and 7 women, age 35.1 years ± 14.7), with 21 hemispheres with the diagnosis of moyamoya disease. During the period 2005-2009, the patients underwent initial and follow-up technetium-99m ethyl cysteinate dimer (Tc-99m ECD) single photon emission computed tomography (SPECT). The 3DSRT was applied to estimate regional CBF at rest and CVR. Time-course changes in CBF and CVR in a region of the middle cerebral artery were analyzed, considering the presence or absence of an ischemic event and revascularization surgery. RESULTS CBF in hemispheres with ischemic events was significantly lower than CBF in hemispheres without ischemic events based on the initial SPECT study (P = 0.001). In 15 hemispheres with a hemodynamic disorder, CBF of the hemispheres in which revascularization was performed was increased significantly after surgery (P = 0.01). In contrast, the follow-up CVR of the hemispheres in which revascularization was not performed was decreased significantly compared with the CVR determined in the initial SPECT study (P = 0.0008). CONCLUSIONS Time-course analysis and quantitative SPECT using the 3DSRT were useful for the evaluation of hemodynamic changes involved in disease progression and revascularization surgery in patients with moyamoya disease. Regular hemodynamic studies are important for patients with hemodynamic disorders to determine whether revascularization surgery is indicated to reduce the risk of future stroke.


Headache | 2012

Bioactive Coils Cause Headache and Fever After Endovascular Treatment of Intracranial Aneurysms

Tomoji Takigawa; Yuji Matsumaru; Yasunobu Nakai; Kazuhiro Nakamura; Mikito Hayakawa; Wataro Tsuruta; Akira Matsumura

Background.— Based on our encounters with patients who have been treated for unruptured intracranial aneurysms by endovascular coil embolization using bioactive coils, we observed that such patients often present with headaches and fever.


Interventional Neuroradiology | 2004

Angiographical Change of Guglielmi Detachable Coils: Treated Cerebral Aneurysm in Acute Stage

Yasunobu Nakai; Makoto Sonobe; T. Takigawa; T. Yamazaki; S. Okamoto; K. Sugita; Yuji Matsumaru

Acute angiographical changes for preventing acute rebleeding on GDC treated cerebral aneurysms were evaluated. From December 2000 to November 2002, 48 total aneurysms in 44 consecutive patients with acute SAH. Acute angiographical evaluations were carried out in 46 aneurysms, including 42 ruptured and 4 unruptured aneurysms. Two cases were excluded because of poor medical condition. In this series, there were no rebleeding cases in acute stage. In the initial embolization for the 46 aneurysms, CO was achieved in eight aneurysms, NR in 15 aneurysms and BF in 23 aneurysms. Acute angiographical observations showed progressive thrombosis in 17 aneurysms (37%). No changes were observed in remaining 29. No recanalization was observed in this series. Only one case of BF, inside the aneurysm bleb was still observed during follow up. Additional embolization was carried out. Progressive thrombosis was frequently observed in GDC treated cerebral aneurysms during acute stage. This angiographical finding seems to show prevention of rebleeding, which is considered important for the management of GDC treatment in acutely ruptured cerebral aneurysm.


Interventional Neuroradiology | 1998

Percutaneous Transluminal Angioplasty for Atherosclerotic Stenosis of the Intracranial Cerebral Arteries. Special reference to the device for reducing the complications drawn from the analysis of our complicated cases.

Akio Hyodo; Yuji Matsumaru; Anno I; Sato H; Kato N; Yasunobu Nakai; Nose T

Percutaneous transluminal angioplasty (PTA) was carried out 43 times for 40 lesions in 38 cases of atheroscrelotic stenosis of the intracranial or skull base cerebral arteries. The stenotic lesions involved the middle cerebral artery in 15 cases, the basilar artery in seven cases, the internal carotid artery (petrous-supraclinoid portion) in 14 cases, and the intracranial vertebral artery in four cases. Nearly all cases were symptomatic, such as TIA or stroke, and the degree of stenosis ranged from 70 to 99 percent, with a mean of 80 percent. PTA was performed using a STEALTH balloon angioplasty catheter. In these trials, PTA was successfully performed (as indicated by a residual stenosis under 50%) 36 times. The initial success rate was 84% and stenosis was reduced from 80% to 25%. Clinical follow-up was performed from 3 to 62 months with a mean of 40 months. During this period, death due to myocardial infarction or pneumonia occurred in four cases, stroke related to previous PTA occurred in one case (due to re-stenosis) and stroke unrelated to previous PTA occurred in two cases. Angiographic follow-up was performed in 30 cases after 36 successful PTA procedures. Re-stenosis was seen in 20% of the cases, symptomatic complication occurred in 7%, and asymptomatic complications occurred in 7% of the cases. There was no mortality in this series. From analysis of complicated cases, there are several characteristic findings on the stenotic lesion. These are the stenotic lesions that located near the bifurcation, involving long segment, or showing irregular shape which is including ulcer or dissection. It is important to keep a fundamental and safe technique to reduce the complication. And besides, it is very important to keep the strict indication and to avoid the high-risk patient from a morphological point of view.


Interventional Neuroradiology | 2001

Rupture of Aneurysms during and after Embolization with Guglielmi Detachable Coils.

Yuji Matsumaru; Makoto Sonobe; Yasunobu Nakai; Takahashi S; Nose T

Between March, 1997 and June, 2000, 104 aneurysms, including 75 ruptured and 29 unruptured aneurysms, were treated with Guglielmi detachable coils by 120 embolizations in our institution. Intraprocedual perforation occurred in four cases, representing 3.3% of the embolizations. Subsequently, two cases deteriorated, and the other two cases recovered completely without any deficit. Aneurysmal perforations mostly occurred in acutely ruptured aneurysms, small aneurysms less than 4 mm, anterior communicating artery aneurysms, or first coil delivery. Rebleedings in the acute period of subarachnoid hemorrhage occurred in four cases of partial occlusion due to aneurysmal morphology, such as a wide neck or an irregular shape. Rebleedings in the chronic period occurred in two cases, one of which rebled two months after partial occlusion, and the other of which rebled 27 months after nearly total occlusion. No subarachnoid hemorrhages documented from previously unruptured aneurysms occurred after embolizations. Insufficient embolization for ruptured aneurysms cannot prevent rebleeding, and partially occluded aneurysms and recurring aneurysms in the follow-up period require immediate re-treatment.


Interventional Neuroradiology | 1999

Percutaneous transluminal angioplasty for atherosclerotic stenosis of the intracranial cerebral arteries. initial results and long-term follow-up.

Akio Hyodo; Kato N; Yasunobu Nakai; Anno I; Sato H; Okazaki M; Yuji Matsumaru; Nose T

Percutaneous transluminal angioplasty (PTA) was carried out 52 times for 49 lesions in 47 cases of atheroscrelotic stenosis of the intracranial or skull base cerebral arteries. The stenotic lesions involved the middle cerebral artery in 21 cases, the basilar artery in eight cases, the internal carotid artery (petrous-supraclinoid portion) in 15 cases, and the intracranial vertebral artery in five cases. Nearly all cases were symptomatic, such as TIA or stroke, and the degree of stenosis ranged from 70 to 99 percent, with a mean of 80 percent. PTA was performed using a STEALTH balloon angioplasty catheter. In these trials, PTA was successfully performed (as indicated by a residual stenosis under 50%) 41 times. The initial success rate was 79% and stenosis was reduced from 80% to 25%. Clinical follow-up was performed from 7 to 84 months with a mean of 44 months. During this period, death due to myocardial infarction or pneumonia occurred in five cases, stroke related to previous PTA occurred in one case (due to re-stenosis) and stroke unrelated to previous PTA occurred in two cases. Angiographic follow-up was performed in 31 cases after 41 successful PTA procedures. Re-stenosis was seen in 20% of the cases, symptomatic complications occurred in 6%, and asymptomatic complications occurred in 6% of the cases. One case suffered severe subarachnoid hemorrhage just after the PTA due to preexisting aneurysm rupture and he died a week after the PTA. So mortality in this series was 2%. From the results described here, we may conclude that PTA of the intracranial or skull base cerebral artery is technically feasible, and it can be performed with relatively low risk. From our results, it may be a useful method and effective for long-term survival of patients. But results from a larger number of patients and more long-term follow-up data are still necessary in order to evaluate the safety and usefulness of this method.


Interventional Neuroradiology | 2014

Anatomical risk factors for ischemic lesions associated with carotid artery stenting.

Go Ikeda; Wataro Tsuruta; Yasunobu Nakai; Masanari Shiigai; Aiki Marushima; Tomohiko Masumoto; Hideo Tsurushima; Akira Matsumura

The purpose of this study was to investigate the anatomical risk factors for ischemic lesions detected by diffusion-weighted imaging (DWI) associated with carotid artery stenting (CAS). DWI was performed within four days after CAS in 50 stenotic lesions between January 2008 and September 2013. We retrospectively analyzed the correlation between the anatomical factors and ischemic lesions associated with CAS. Post-procedural DWI revealed new ischemic lesions after 24 (48%) of the 50 CAS procedures. All three patients with common carotid artery tortuosity, defined as the presence of severe angulation (less than 90 degrees) in the common carotid artery, developed new ischemic lesions. However, there were no significant differences between the patients with and without tortuosity, likely due to the small number of cases. Meanwhile, seven of eight patients with internal carotid artery tortuosity, defined as the presence of severe angulation (less than 90 degrees) in the cervical segment of the internal carotid artery, developed new ischemic lesions. A multivariate analysis showed internal carotid artery tortuosity (odds ratio: 11.84, 95% confidence interval: 1.193–117.4, P= 0.035) to be an independent risk factor for the development of ischemic lesions associated with CAS. Anatomical factors, particularly severe angulation of the internal carotid artery, have an impact on the risk of CAS. The indications for CAS should be carefully evaluated in patients with these factors.

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Go Ikeda

University of Tsukuba

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