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Dive into the research topics where Naoya Kuwayama is active.

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Featured researches published by Naoya Kuwayama.


Neurochemical Research | 1997

Elevation of platelet activating factor, inflammatory cytokines, and coagulation factors in the internal jugular vein of patients with subarachnoid hemorrhage

Yutaka Hirashima; Shin Nakamura; Shunro Endo; Naoya Kuwayama; Yuchi Naruse; Akira Takaku

The aim of the present study was to examine the changes of inflammatory and coagulation factors in blood of the internal jugular vein, not of peripheral vein, in patients with subarachnoid hemorrhage (SAH). The results show that while interleukin-6 (IL-6) and platelet activating factor (PAF) concentrations increased within first 4 days after SAH and remained elevated up to 14 days, interleukin-1 β (IL-1 β showed a transient increase between 5–9 days after SAH and tumor necrosis factor-α (TNF-α) remained unchanged. Also different coagulation factors were increased between 5–9 days after SAH. Moreover, patients with delayed ischemic neurological deficits (DIND) displayed the highest levels of PAF and the coagulation factors, von Willebrand factor (vWF) and thrombin-antithrombin III complex (TAT). These results suggest that elevation of PAF and other inflammatory cytokines following SAH may cause the hypercoagulation state that is associated with cerebral vasospasm and internal jugular vein may be more adequate vessel for sampling blood to examine these factors.


World Neurosurgery | 2011

Determinants of Poor Outcome After Aneurysmal Subarachnoid Hemorrhage when both Clipping and Coiling Are Available: Prospective Registry of Subarachnoid Aneurysms Treatment (PRESAT) in Japan

Waro Taki; Nobuyuki Sakai; Hidenori Suzuki; Akio Hyodo; Shigeru Nemoto; Toshio Hyogo; Tomoaki Terada; K Satoh; Naoya Kuwayama; Shigeru Miyachi; Masaki Komiyama; Masayuki Ezura; Yuichi Murayama; Hiroshi Sakaida; Masayuki Maeda; H Nagai; T Kataoka; S Ishihara; Y Koguchi; S. Kobayashi; Y Enomoto; K Yamada; Shinichi Yoshimura; Yasushi Matsumoto; Masaru Hirohata; H Adachi; Y Ueno; T Kunieda; Chiaki Sakai; H Yamagami

OBJECTIVE To examine current determinants of poor outcome after aneurysmal subarachnoid hemorrhage (SAH) when ruptured aneurysms are treated with either microsurgery (clipping) or endovascular treatment (coiling) depending on each patients characteristics. METHODS Between March 2006 and February 2007, 534 patients with SAH were enrolled in the Prospective Registry of Subarachnoid Aneurysms Treatment (PRESAT) project. Patients were treated according to the preference of investigators who were experienced in performing both clipping and coiling. Factors influencing poor outcome (12-month modified Rankin Scale [mRS], 3-6) were determined using multivariate logistic regression analyses. RESULTS In this cohort, 32.4% of patients were World Federation of Neurosurgical Societies (WFNS) grade IV-V, and 28.1% had a poor outcome. Clipping was preferably performed for small aneurysms with a wide neck and for middle cerebral artery (MCA) aneurysms, whereas coiling was preferred for larger, internal carotid artery (ICA) and posterior circulation aneurysms. In addition to increasing age, admission WFNS grade IV-V, preadmission aneurysmal rerupture, vasospasm-induced cerebral infarct, pneumonia, sepsis, shunt-dependent hydrocephalus and seizure, postclipping hemorrhagic complications (odds ratio 4.8, 95% confidence interval 1.5-15.3, P < 0.01), and postcoiling ischemic complications (odds ratio 4.4, 95% confidence interval 1.3-15.2, P < 0.05) significantly caused poor outcomes, although the complications did not affect mortality. Type of treatment modality and size and location of aneurysms did not influence outcome. CONCLUSIONS Introducing an endovascular treatment option has made aneurysm characteristics less important to outcome, but procedural complications are problematic and should be reduced to improve outcome.


Acta Neurochirurgica | 1998

Vasa vasorum of the intracranial arteries.

M. Takaba; S. Endo; M. Kurimoto; Naoya Kuwayama; Michiharu Nishijima; Akira Takaku

SummaryMost of the major extracranial arteries have vasa vasorum which play an important role in some pathological conditions. However, in the intracranial arteries, the existence of vasa vasorum and their pathological implication have not been adequately investigated. We examined the distribution and incidence of vasa vasorum in the major cerebral arteries and their relationships to certain clinical factors in 50 autopsy cases performed between 1987 and 1994. By light microscopy, vasa vasorum were found in 36 of 50 patients. Of 36 patients, vasa vasorum in 30 cases were localizedly observed in the tunica adventitia and the in other 6 were distributed in the tunica media accompanied by intramural haemorrhage. Existence of vasa vasorum was more common in the proximal arteries (vertebral, internal carotid, and basilar arteries) than in the distal arteries (middle cerebral and anterior cerebral arteries). Vasa vasorum were found more frequently in aged patients with severe atherosclerosis and those with cerebrovascular diseases. Our results indicated that intracranial vasa vasorum existed with a higher frequency in the tunica adventitia of the vertebral and internal cerebral arteries, and the incidence of vasa vasorum related to severity of atherosclerosis. The development of vasa vasorum in the tunica media may reflect some pathological changes of cerebral arteries.


Cerebrovascular Diseases | 2003

Independent Predictors of Late Hydrocephalus in Patients with Aneurysmal Subarachnoid Hemorrhage – Analysis by Multivariate Logistic Regression Model

Yutaka Hirashima; Hideo Hamada; Nakamasa Hayashi; Naoya Kuwayama; Hideki Origasa; Shunro Endo

Object: We determined independent variables contributing to the development of late hydrocephalus after subarachnoid hemorrhage (SAH). Methods: A total of 114 consecutive patients who underwent surgery for aneurysms within 72 h after SAH were studied. Thirty-nine patients underwent ventriculoperitoneal shunt (VPS) placement (14 patients within 30 days and 25 patients more than 30 days after onset). Univariate and multivariate analyses were performed to assess relationships among various variables and shunt placement. Results: Three variables were found to be independently associated with VPS patients: (1) the rate of SAH clearance; (2) the duration of external cerebrospinal fluid drainage, and (3) presence of neurological deficits 2 weeks after surgery, which indicates brain damage mainly caused by intraoperative manipulation and cerebral vasospasm. Conclusion: As in previous reports, intraoperative clot removal and duration of external CSF drainage were found to be closely related to the incidence of hydrocephalus. Brain damage due to intraoperative manipulation and cerebral vasospasm is seemed to be involved in the occurrence of late hydrocephalus in this study.


Surgical Neurology | 1996

Acute pathologic features with angiographic correlates of the nearly or completely occuluded lesions of the cervical internal carotid artery

Shunro Endo; Yutaka Hirashima; Masanori Kurimoto; Naoya Kuwayama; Michiharu Nishijima; Akira Takaku

BACKGROUND The true pathologic process of nearly or completely occluded lesions of the cervical internal carotid artery (ICA) has not been studied sufficiently. This information is important in determining the critical indications for endarterectomy. METHODS Acute pathologic features of these advanced occlusive lesions of the ICA were studied in 40 patients who underwent emergency carotid endarterectomy. Gross morphologic and histopathologic features of these occlusive lesions were examined, and the relationship between the clinical information and the pathologic characteristics was investigated. RESULTS Thirty-seven lesions had histologic features of advanced atherosclerosis complicated by fresh intraplaque hemorrhages with or without transintimal extension. Thinwalled neovessels were thought to be an important etiologic factor in producing intraplaque hemorrhage. The remaining three lesions without these changes had strangulated embolic material at the occluded portion. A good correlation between these pathologic features and angiographic findings was found. CONCLUSION The presented results clearly indicate that intraplaque hemorrhage is the most important factor in producing and determining the acute pathologic features of symptomatic and advanced atheromatous occlusive ICA lesions.


Acta Neurochirurgica | 2009

Changes in cognitive function during the 1-year period following endarterectomy and stenting of patients with high-grade carotid artery stenosis

Akiko Takaiwa; Nakamasa Hayashi; Naoya Kuwayama; Naoki Akioka; Michiya Kubo; Shunro Endo

BackgroundIn patients with severe carotid artery stenosis, cognitive decline and changes in cognitive function before to after treatment have been noted, though the true effects of treatment in such patients remain unclear. A convenient and repeatable neuropsychological test battery is needed for such patients.MethodsIn 26 patients with severe carotid artery stenosis treated by carotid endarterectomy (CEA) and stenting (CAS), cognitive function was examined before and 1 week, 3 months, 6 months, and 1 year after treatment. RBANS and MMSE were selected as a test battery, and changes in test scores and long-term results of revascularization were evaluated.ResultsRBANS was useful and suitable for neuropsychological testing in such patients, and yielded the following results: (1) Patients before treatment had, on average, RBANS scores rated low average, with mild but relatively diffuse cognitive impairment; (2) RBANS scores were increased significantly at 3 months after CEA and CAS, and cognitive improvement was maintained over 1 year; and (3) scores were decreased temporarily at 1 week after CEA, but not after CAS.ConclusionsPatients with severe carotid artery stenosis exhibited mild decline in cognitive function, which was improved after CEA and CAS. RBANS is a suitable test battery for this type of patient.


Journal of Stroke & Cerebrovascular Diseases | 2012

Periprocedural Cilostazol Treatment and Restenosis after Carotid Artery Stenting: The Retrospective Study of In-Stent Restenosis after Carotid Artery Stenting (ReSISteR-CAS)

Hiroshi Yamagami; Nobuyuki Sakai; Yuji Matsumaru; Chiaki Sakai; Yutaka Kai; Kenji Sugiu; Toshiyuki Fujinaka; Yasushi Matsumoto; Shigeru Miyachi; Shinichi Yoshimura; Toshio Hyogo; Naoya Kuwayama; Akio Hyodo

Restenosis after carotid artery stenting (CAS) is a critical issue. Cilostazol can reduce restenosis after interventions in coronary or femoropopliteal arteries. We investigated whether periprocedural cilostazol treatment was related to the incidence of in-stent restenosis (ISR) or target vessel revascularization (TVR) after CAS. The study group comprised 553 of 580 patients who underwent CAS between April 2003 and August 2006 and were followed for 30 months after the procedure. ISR was defined as stenosis of at least 50% detected on angiography or ultrasonography. TVR was defined as revascularization of the treated carotid artery. During CAS, 207 patients (37.4%) were treated with cilostazol. Over 30 months, ISR occurred in 23 patients (4.2%), TVR occurred in 16 patients (2.9%), and either ISR or TVR occurred in 25 patients (4.5%). The incidence of ISR or TVR was significantly lower in the cilostazol-treated group than in the untreated group (1.4% vs 6.4%; log-rank P = .006). In a multivariate analysis, cilostazol treatment (hazard ratio [HR], 0.28; 95% confidence interval [CI], 0.08-0.95; P = .041) and stent diameter (HR, 0.73/1-mm increase; 95% CI, 0.54-0.99; P = .044) were independent factors for the occurrence of ISR or TVR. The incidence of a composite of events, including thromboembolism, hemorrhage, death, and TVR, tended to be lower in the cilostazol-treated group than in the untreated group (15.0% vs 19.9%; log-rank P = .17). Periprocedural cilostazol treatment was associated with lower rates of ISR and retreatment after CAS. A prospective randomized controlled trial is needed to clarify the effect of cilostazol on ISR after CAS.


American Journal of Neuroradiology | 2010

Intracranial dural arteriovenous fistula with retrograde cortical venous drainage: use of susceptibility-weighted imaging in combination with dynamic susceptibility contrast imaging.

Kyo Noguchi; Naoya Kuwayama; Michiya Kubo; Yuichi Kamisaki; K. Kameda; Gakuto Tomizawa; H. Kawabe; Hikaru Seto

BACKGROUND AND PURPOSE: SWI is a new MR imaging method that maximizes sensitivity to magnetic susceptibility effects with phase information for visualizing small cerebral veins. The purpose of this study was to report the use of SWI in combination with DSC in examining related RCVD in patients with intracranial DAVFs. MATERIALS AND METHODS: Ten patients with angiographically confirmed DAVFs with RCVD underwent conventional MR imaging, SWI, and DSC. The ability of SWI to depict dilated cerebral veins was evaluated and then compared with DSC. The hemispheres of patients with DAVFs were grouped into affected (with RCVD) or nonaffected (without RCVD) categories by angiography. Four patients had bilaterally affected hemispheres. A total of 14 affected hemispheres in patients with DAVFs with RCVD were evaluated. RESULTS: SWI showed dilated cerebral veins on the surface of the brain in all (100%) of the 14 affected hemispheres in patients with DAVFs with RCVD and deep in the brain in 9 (64%). T2-weighted imaging showed prominent flow-voids on the surface of the brain in 10 (71%) of the 14 affected hemispheres in patients with DAVFs with RCVD and deep in the brain in 5 (36%). DSC showed increased cerebral blood volume in all of the 14 affected hemispheres. The SWI findings regarding dilated veins on the surface of the brain corresponded well with the areas of increased cerebral blood volume. CONCLUSIONS: SWI in combination with DSC could be used to characterize the presence of RCVD in patients with DAVFs.


Surgical Neurology | 1994

Dural arteriovenous fistulae involving the transverse-sigmoid sinus and foramen magnum

Naoya Kuwayama; Takuya Akai; Yukio Horie; Michiharu Nishijima; Shunro Endo; Akira Takaku

The authors present a rare case of dural arteriovenous fistulae (AVFs) involving both the transverse-sigmoid sinus and the foramen magnum, which was treated successfully with multi-staged endovascular procedures. The transverse-sigmoid sinus, which was thrombosed proximally and distally, was occluded by transarterial embolization followed by intraoperative embolization of the sinus using platinum coils. The dural AVF involving the foramen magnum was occluded via a transvenous approach.


Surgical Neurology | 2008

A development of atheromatous plaque is restricted by characteristic arterial wall structure at the carotid bifurcation

Emiko Hori; Nakamasa Hayashi; Hideo Hamada; Toru Masuoka; Naoya Kuwayama; Yutaka Hirashima; Hideki Origasa; Osamu Ohtani; Shunro Endo

BACKGROUND It is said atheromatous plaque is located very focally, but there have been few reports regarding this matter. Various aspects of the pathogenesis of the development of atheromatous plaque at the carotid bifurcation have previously been discussed. We have noted the correlation of plaque localization with characteristics of the cervical carotid artery wall. METHODS Morphological and histopathologic changes in the carotid bifurcation were examined in 72 cadaver cases with or without atheromatous plaque. We determined the level at which the wall structure changed to muscular artery from elastic artery and analyzed its influence on the development of atheromatous plaque. RESULT Atheromatous plaques at the distal site of the ICA extended within 0 to 37 mm from the carotid bifurcation. The proximal side of the CCA more than 5 mm away from the bifurcation was elastic artery, whereas the distal side of the ICA more than 15 mm from the bifurcation was muscular artery. The area of the carotid bifurcation between elastic artery and muscular artery was a transitional zone. Approximately 80% of them were located within 15 mm, and these areas were coincident with the transitional zone. CONCLUSION Most atheromatous plaque was located in the transitional zone. The arterial wall structure is related to the development of atheromatous plaque at the cervical carotid bifurcation.

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Michiharu Nishijima

Memorial Hospital of South Bend

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