Masanari Onizuka

Fukuoka University, Hukuoka, Fukuoka, Japan

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Publications (22)25.79 Total impact

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    ABSTRACT: Three women older than 75 years presented with spontaneous superficial temporal artery (STA) pseudoaneurysms manifesting as a pulsatile mass in the preauricular region. None of the patients had a history of trauma. Histological examination of the surgically removed masses identified pseudoaneurysms based on the presence of connective tissue and adventitia. Spontaneous STA pseudoaneurysms are extremely rare. We suggest that all 3 aneurysms were associated with latent dissection and external force exerted by the frames of glasses.
    Neurologia medico-chirurgica 01/2011; 51(10):713-5. · 0.49 Impact Factor
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    ABSTRACT: Changes in the cerebral blood flow (CBF) are important for planning postoperative care in patients treated by carotid artery stenting (CAS). The relationship between intraprocedural changes in the angiographic cerebral circulation time (CCT) and perioperative CBF changes were retrospectively studied in 49 CAS procedures performed in 46 patients with carotid artery stenosis. The CCT, defined as the interval between the timing of maximal opacification at the terminal portion of the internal carotid artery and at the cortical vein, was determined by referring to time-density curves of data obtained from routine intraprocedural digital subtraction angiography. The intraoperative change in CCT (Delta CCT) was calculated for each of the 49 procedures. CBF studies, using dynamic perfusion computed tomography, were performed 10-2 days before and 2-4 days after CAS. Perioperative changes in the ratio of the CBF in the territory of the middle cerebral artery on the affected side to CBF on the contralateral side (%CBF) were calculated by subtracting pre- from postoperative %CBF (Delta%CBF) and the correlation between Delta CCT and Delta%CBF was evaluated. Mean CCT was shortened by 1.1 seconds from 5.3 to 4.2 seconds after CAS. Mean %CBF increased by 11.9% from 91.8% to 103.7% after the procedure. Delta CCT and Delta%CBF showed a significant positive correlation (r = 0.61, p = 0.008). Intraprocedural changes in angiographic CCT are predictive of postoperative CBF in patients with CAS.
    Neurologia medico-chirurgica 01/2010; 50(4):269-74. · 0.49 Impact Factor
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    ABSTRACT: A 62-year-old man experienced transient episodes of vertigo associated with left upper extremity weakness. Cerebral angiography showed 75% right internal carotid artery (ICA) stenosis and divergence of a persistent primitive hypoglossal artery (PPHA) distal to the stenosis. The area of stenosis was at a high position and he had a past medical history of congestive heart failure, which contraindicated carotid endarterectomy (CEA). Therefore, carotid artery stenting (CAS) was performed with single distal balloon protection. The stenotic area was restored and he was discharged without suffering recurrent attacks. CAS may be an effective alternative treatment to CEA to prevent further ischemic attacks in the posterior circulation in patients with PPHA. CAS using simple embolic protection devices is possible if the distance between the distal end of the ICA stenosis and the origin of the PPHA is sufficiently long.
    Neurologia medico-chirurgica 01/2010; 50(10):921-4. · 0.49 Impact Factor
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    ABSTRACT: We assessed the morphological change of calcified plaque after carotid artery stenting (CAS) in vessels with heavily calcified circumferential lesions and discuss the possible mechanisms of stent expansion in these lesions. We performed 18 CAS procedures in 16 patients with severe carotid artery stenosis accompanied by plaque calcification involving more than 75% of the vessel circumference. All patients underwent multidetector-row computed tomography (MDCT) to evaluate lesion calcification before and within 3 months after intervention. The angiographic outcome immediately after CAS and follow-up angiographs obtained 6 months post-CAS were examined. The preoperative mean arc of the calcifications was 320.1 +/- 24.5 degrees (range 278-360 degrees ). In all lesions, CAS procedures were successfully carried out; excellent dilation with residual stenosis <or=30% was achieved in all lesions. Post-CAS MDCT demonstrated multiple fragmentations of the calcifications in 17 of 18 lesions (94.4%), but only cracks in the calcified plaque without fragmentation in one (5.6%). Angiographic study performed approximately 6 months post-CAS detected severe restenosis in one lesion (5.6%) without fragmentation of calcified plaque. Excellent stent expansion may be achieved and maintained in heavily calcified circumferential carotid lesions by disruption and fragmentation of the calcified plaques.
    Neuroradiology 12/2009; 52(9):831-6. · 2.70 Impact Factor
  • Kouhei Nii, Masanari Onizuka, Kiyoshi Kazekawa
    Brain and nerve = Shinkei kenkyū no shinpo 09/2008; 60(8):970-1.
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    ABSTRACT: Because of its high complication rate, the endovascular treatment (EVT) of anterior communicating artery (ACoA) aneurysms less than 3 mm in maximum diameter remains controversial. We evaluated EVT of tiny ruptured ACoA aneurysms with Guglielmi detachable coils (GDCs). We treated 19 ruptured ACoA aneurysms with a maximum diameter of <or=3 mm with GDCs. The pretreatment Hunt and Hess score was grade 1 in four patients, grade 2 in six, grade 3 in six, and grade 4 in three. The patients were clinically assessed before and after treatment and with multiple angiographic follow-up studies. All EVTs were successful; there were no aneurysm perforations or any other treatment-related complications. In five patients older than 80 years the transfemoral approach was difficult, and the direct carotid approach was used. Complete and near-complete occlusion was achieved in 16 patients (84.2%) and 3 patients (15.8%), respectively. Of the 19 patients, 16 (84.2%) were followed angiographically for a median of 38.5 months (range 16-72 months). None demonstrated recanalization of the aneurysm requiring additional treatment. In 15 patients (78.9%) the final outcome was good (modified Rankin scale, mRS, score 0-2), and 3 patients (15.8%) died or suffered severe disability (mRS score 4-6). None of 18 patients who were followed clinically for a median of 39.5 months (range 17-84 months) experienced rebleeding. Even tiny ruptured ACoA aneurysms can be safely treated by EVT by expert neurointerventionalists using advanced techniques.
    Neuroradiology 07/2008; 50(6):509-15. · 2.70 Impact Factor
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    ABSTRACT: Changes in the location and length of the Wallstent RP during carotid artery stenting (CAS) were evaluated using intraoperative videos of 28 patients with carotid artery stenosis who underwent CAS with a 10/20 mm Wallstent RP to determine the appropriate stent placement. The stent was deployed after its midpoint was positioned over a virtual center line, the perpendicular line which crossed the most stenotic point of the lesion on the road mapping image. The length of the stenotic lesion, the changes in the locations of the distal and proximal ends of the stent, and the changes in stent length were examined. The distal end of the stent moved a maximum of 6.1 mm toward the proximal side to a point 19.9 mm from the virtual center line. The proximal end moved a maximum of 11.3 mm toward the distal side to a point 14.7 mm from the virtual center line. The stent length ranged from 37.7 to 44.5 mm (mean 41.2 mm). The 10/20 mm Wallstent RP placed by our technique covers the entire lesion with no less than 5.7 mm of margin over the segment distal to the lesion in patients with stenotic segments shorter than 29.4 mm.
    Neurologia medico-chirurgica 07/2008; 48(6):249-52; discussion 252-3. · 0.49 Impact Factor
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    ABSTRACT: A 50-year-old man presented with a symptomatic aneurysm arising from the right inferior cavernous sinus artery (ICSA) associated with a cerebral arteriovenous malformation (AVM) manifesting as a 3-month history of progressive right abducens nerve palsy. Cerebral angiography demonstrated a high-flow AVM and a saccular aneurysm arising from the right ICSA acting as a meningeal feeder. The symptom was thought to be attributable to aneurysmal mass effect rather than the AVM. The aneurysm was successfully treated with endovascular embolization and the symptom improved gradually. Hemodynamic stress in the ICSA may have resulted in the development of the aneurysm of the ICSA. Meningeal artery aneurysm presenting with cranial nerve palsy is extremely uncommon. The present case illustrates the need for detailed evaluation of the external carotid artery and internal carotid artery vasculature in patients with cerebral AVMs.
    Neurologia medico-chirurgica 07/2008; 48(6):257-8. · 0.49 Impact Factor
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    ABSTRACT: An 82-year-old man with an asymptomatic left high-grade carotid stenosis was treated with carotid artery stenting (CAS) under distal protection. The procedure consisted with predilation with a 5 x 40 mm percutaneous transluminal angioplasty (PTA) balloon, deployment of a 10 x 20 mm self-expandable stent, post-dilation with a 7 x 20 mm PTA balloon, and aspiration of debris with 60 ml of blood. The cervical carotid angiogram immediately after deflation of the distal blocking balloon demonstrated a small in-stent filling defect of the contrast medium that protruded from the anterior wall of the carotid artery. The following cranial carotid angiogram showed abrupt occlusion of the left middle cerebral artery (MCA). Because the in-stent lesion had vanished in the repeat study after recognition of this embolic event, it was suggested that an embolus had been liberated from the in-stent lesion, reaching the left MCA and obliterating it. In this case, the embolus was speculated to originate in the ruptured plaque, which protruded into the stent through the cells of the device and became liberated into the bloodstream. Attention should be paid so as not to overlook any plaque protrusion, which may be seen subsequently as a cerebral embolism on the angiogram obtained immediately after CAS.
    Radiation Medicine 06/2008; 26(5):318-23.
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    ABSTRACT: Our aim was to assess the feasibility of carotid artery stent placement (CAS) for calcified lesions. Using embolic protection devices (EPDs), we performed 51 CAS procedures in 43 patients with severe carotid artery stenosis accompanied by plaque calcification. Before intervention, all lesions were subjected to multidetector-row CT. The arc of the circumferential plaque calcification was measured on axial source images at the site of maximal luminal stenosis, and the total volume of the plaque calcification was determined. The angiographic outcome immediately after CAS, and intra- and postoperative complications were recorded. The mean arc of calcification was 201.1 +/- 72.3 degrees (range, 76-352 degrees ), and the mean of the total calcification volume was 154.9 +/- 35.4 mm(3) (range, 92-2680 mm(3)). Balloon rupture occurred in 1 procedure (2.0%) at predilation angioplasty; all 51 CAS procedures were successful without clinical adverse effects. Although there was a correlation between the arc of plaque calcification and residual stenosis (r = 0.6, P < .001), excellent dilation with residual stenosis < or =30% was achieved in all lesions. There was no correlation between the total volume of calcification and residual stenosis. None of the patients developed stroke or death within 30 days of the CAS procedure. CAS by using EPDs to treat lesions with plaque calcification is feasible even in patients with near-total circumferential plaque calcification.
    American Journal of Neuroradiology 05/2008; 29(8):1590-3. · 3.17 Impact Factor
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    ABSTRACT: This study retrospectively reviewed 227 patients with ruptured solitary cerebral aneurysm who underwent endovascular embolization with detachable coils between March 1997 and March 2006 to establish the incidence of rebleeding after endovascular treatment for ruptured cerebral aneurysm and identify the risk factors. The site and size of the aneurysm, the interval between treatment and rebleeding, and the outcome were investigated in six of the 227 patients (2.6%) who rebled after treatment. Four patients had large or giant aneurysms located on the internal carotid artery at the origin of the posterior communicating artery. The interval between treatment and rebleeding was less than 1 year in four patients (mean 394.2 days). Two patients died, and the survivors had modified Rankin Scale scores of 0, 2, 3, and 4. Re-embolization was performed in four patients and no further bleeding occurred during the mean follow-up period of 1.9 years after re-treatment. Patients with giant aneurysms of the internal carotid artery are at increased risk for rebleeding. Re-treatment should be considered if there is conventional and/or magnetic resonance angiographic evidence of dome filling. Patients with ruptured cerebral aneurysms must be followed up with diagnostic imaging closely during the first 12 months post-embolization because rebleeding frequently occurs within 1 year after initial treatment. Re-embolization is safe and effective in patients with recurrent hemorrhage from aneurysms previously embolized with detachable coils.
    Neurologia medico-chirurgica 11/2007; 47(10):439-45; discussion 446-7. · 0.49 Impact Factor
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    ABSTRACT: The PercuSurge system is a distal balloon embolic protection device used for carotid artery stenting (CAS). We performed a retrospective study on the prognosis and clinical effects of spasms induced by the PercuSurge GuardWire system (PercuSurge-induced spasm). We performed CAS in 118 carotid stenoses using the PercuSurge system. Of the 118 procedures, 31 (26.3%) of the patients experienced PercuSurge-induced spasm, and all underwent postoperative follow-up studies by cerebral angiography and antiplatelet treatment. On follow-up angiograms obtained a mean of 5.2 months (range 3-10 months) after CAS, all 31 PercuSurge-induced spasms had disappeared, and no delayed stenosis was found at the sites where the spasms had occurred. No ischemic events due to the spasms occurred during a mean follow-up of 13 months (range 3-32 months). In the hands of physicians experienced in endovascular surgery, CAS using the PercuSurge system is a safe method with which to treat patients with carotid stenosis. Our study demonstrated that PercuSurge-induced spasms had no morphological or clinical adverse effects.
    Radiation Medicine 09/2007; 25(7):335-8.
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    ABSTRACT: A 44-year-old male with right vertebral arteriovenous fistula accompanied with tinnitus, underwent endovascular treatment using GDC. A digital subtraction angiography clearly showed one fistula flowed from the right vertebral artery (VA) to the vertebral venous plexus, while the right VA close to the fistula was interupped with HyperForm. The tip of the micro catheter was placed in the vertebral venous plexus through fistula from the right VA, and the vertebral venous plexus around the fistula was embolized with 4 GDCs. Blood flow of the right VA was maintained. Follow-up angiography undertaken 6 months after the operation didn't show the recurrence of arteriovenous fistula.
    Brain and nerve = Shinkei kenkyū no shinpo 09/2007; 59(8):887-90.
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    ABSTRACT: The term "accordion effect" is used to describe a mechanical distortion of tortuous arteries mimicking spasm or dissection. This phenomenon has been reported in patients undergoing percutaneous coronary intervention. To our knowledge, this is the first documentation of the accordion effect during carotid artery intervention. Two patients who developed the accordion effect during carotid artery stenting (CAS) are described. Angiograms obtained just after CAS showed a stenosing lesion with wall irregularity at the distal part of the stent. This lesion disappeared and tortuosity of the internal carotid artery developed after withdrawing the guidewire until its floppy segment rested equally on the lesion. In another patient, the lesion did not disappear completely until the guiding catheter had been withdrawn to the proximal portion of the common carotid artery. We conclude that these stenosing lesions reflected the accordion effect. It is essential to differentiate the accordion effect from dissection, spasm, and thrombosis because the management is importantly different. We report our findings and present a review of the literature.
    Neuroradiology 08/2007; 49(7):567-70. · 2.70 Impact Factor
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    ABSTRACT: Carotid artery stenting for carotid bifurcation stenosis usually uses the transfemoral approach. However, in patients with proximal common carotid artery (CCA) stenosis, the guiding catheter is difficult to introduce into the narrow origin of the CCA without risking cerebral embolization before activation of the protection device. A technique of cerebral protection by internal carotid artery (ICA) clamping with or without simultaneous external carotid artery (ECA) clamping was used to treat patients with proximal CCA stenosis by the retrograde direct carotid approach. The carotid bifurcation was surgically exposed and retrograde catheterization was performed to approach the stenosis. The ICA was clamped during angioplasty and stenting to avoid cerebral embolization. The ECA was clamped simultaneously if any extracranial-intracranial anastomosis was present. None of five patients treated with this technique experienced ischemic complications attributable to this technique.
    Neurologia medico-chirurgica 07/2007; 47(6):285-7; discussion 287-8. · 0.49 Impact Factor
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    ABSTRACT: We assessed the long-term follow-up examinations and complications of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic ostial vertebral artery (VA) stenosis. A retrospective study was done to evaluate 12 patients with symptomatic ostial VA stenosis who underwent PTAS. Six patients were treated with the Palmaz stent and six with a balloon-expandable coronary stent. Initial angiographic follow-up examination was conducted about 12 months after PTAS in all patients. Simple radiographic, ultrasonographic and clinical follow-up examinations were scheduled every 6 months. Excellent dilatation was achieved in all patients without any procedural complications. Initial angiographic follow-up obtained at a mean of 13 months after PTAS detected no restenosis. However, an asymptomatic severe restenosis was detected at 24 months after PTAS in one patient (8%). During a mean follow-up of 31.5 months, three stent fractures were detected in deployed coronary stents (50%). None of the stent fractures was associated with either recurrent stroke or restenosis. No patients developed recurrent symptoms during the follow-up period. PTAS for symptomatic ostial VA stenosis is effective in preventing recurrent stroke. As the open-cell single-joint type of stent is associated with the risk of fracture, long-term follow-up examinations including simple radiography are needed.
    Neuroradiology 04/2007; 49(3):253-7. · 2.70 Impact Factor
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    ABSTRACT: After coil embolization for an aneurysm, edema surrounding the aneurysm revealed by magnetic resonance imaging (MRI) is rarely seen and is usually associated with neurological symptoms. Perianeurysmal edema was found by postoperative MRI in three out of 182 patients with cerebral aneurysm, which was treated with Guglielmi Detachable Coil (GDC), and neurological symptoms developed simultaneously. In cases where neurological symptoms improved with conservative medical treatment, a temporary increase in the volume of an aneurysm, due to coil and thrombus formation, may result in edema. In cases where symptoms were not alleviated with conservative medical treatment, persistent water-hammer effect against the residual lumen of the aneurysm as well as an increase in the volume of aneurysm by hemorrhage in the aneurysmal wall may contribute to the development of perianeurysmal edema. Consideration of the mechanism of edema development by neurological symptoms, MRI findings, and angiographic findings is needed in order to select appropriate treatment.
    Interventional Neuroradiology 03/2007; 13 Suppl 1:145-50. · 0.77 Impact Factor
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    ABSTRACT: We present an alternative endovascular approach to treat dural carotid cavernous fistulae (dural CCF) that drain only into the superior ophthalmic vein. Four cases of cavernous dural AVFs that could not be treated via the inferior petrosal vein were accessed via the direct superficial temporal vein approach through the superior ophthalmic vein. Successful embolization was documented radiographically and clinically in all patients. The trans-superficial temporal vein approach is safe and useful for inaccessible dural CCFs through the inferior petrosal sinus.
    Interventional Neuroradiology 03/2007; 13 Suppl 1:64-7. · 0.77 Impact Factor
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    ABSTRACT: The authors herein report a case of a ruptured dissection of the superior cerebellar artery (SCA). A 68-year-old man presented with symptons of sudden headache and nausea. The CT scan revealed the presence of both a subarachnoid hemorrhage (SAH) and acute hydrocephalus. The left vertebral angiogram showed an fusiform dilatation in the cerebellomesencephalic segment of the left SCA. Endovascular embolization of the aneurysm and SCA was successfully performed using Guglielmi detachable coils (GDCs). No delayed ischemic deficits were observed after the treatment. A dissection of the distal segment of the SCA is a very rare occurrence. We believe endovascular embolization using GDCs to be an effective and less invasive therapy for the treatment of an SCA dissection with SAH.
    Brain and nerve = Shinkei kenkyū no shinpo 02/2007; 59(1):72-5.
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    ABSTRACT: A 17-year-old woman presented with a rare aneurysm at the junction of the persistent primitive trigeminal artery (PPTA) and the internal carotid artery (ICA) manifesting as left abducens nerve paresis. The aneurysm and the ICA were both successfully occluded with coils. The balloon occlusion test used the HyperForm balloon microcatheter to seal the PPTA and ICA, which is very important to determine the optimal treatment strategy for a PPTA aneurysm.
    Neurologia medico-chirurgica 12/2006; 46(11):541-3. · 0.49 Impact Factor