Publications by authors named "Ryoo Yamamoto"

Purpose: Tandem occlusion, in which the intracranial artery is obstructed along with proximal carotid occlusive or stenotic lesions, occurs in 10-15% of patients with large vessel occlusion. Our study introduces a novel technique for tandem occlusion treatment that involves the simultaneous coaxial deployment of a percutaneous transluminal angioplasty balloon and aspiration catheters with the delivery wire of a stent retriever. After percutaneous transluminal angioplasty of the carotid lesion with a thin balloon catheter, the aspiration catheter was advanced over the balloon to eliminate the ledge between the catheter tip and delivery wire.

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Background: The clinical benefits of faster recanalization in acute large vessel occlusion are well recognized, but the optimal procedure time remains uncertain. The aim of this study was to identify patient characteristics that necessitate puncture-to-recanalization (P-R) time within 30 min to achieve favorable outcome.

Methods: We evaluated the patients from a prospective, multicenter, observational registry of acute ischemic stroke patients.

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Article Synopsis
  • The study investigated the impact of treatment timing (on-duty vs. off-duty hours) on outcomes for patients undergoing endovascular treatment for acute ischemic stroke.
  • It analyzed data from 1,571 patients in a multicenter registry, focusing on the modified Rankin Scale (mRS) at 90 days post-stroke as the primary outcome measure.
  • Results indicated no significant difference in mRS scores between on-duty and off-duty patients, but off-duty patients experienced longer door-to-puncture times, leading to poorer outcomes when that time exceeded 60 minutes, influenced by factors like low NIHSS scores and diabetes.
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  • This study evaluated how effective and safe thrombectomy is for acute ischaemic stroke patients who had some pre-stroke disability, using data from 2313 patients.
  • Out of the 2136 patients analyzed, 33.3% with pre-stroke disabilities achieved a favorable outcome (mRS score of 0-3) after 90 days, with NIHSS scores being a significant predictor of success.
  • The findings suggest that both intravenous t-PA and thrombectomy are safe and particularly beneficial for patients with lower NIHSS scores experiencing stroke-related disabilities.
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Objectives: A foreign body granuloma after an endovascular intervention is a rare complication. Some cases of foreign body granulomas, especially after coil embolization, have been reported. However, only four cases of foreign body granulomas after mechanical thrombectomy (MT) have previously been reported.

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Background: Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are common treatments for ischemic stroke prevention in patients with carotid artery stenosis. However, the beneficial effects of CEA/CAS for cerebral hypoperfusion due to carotid artery stenosis have yet to be fully established. As dizziness is a common symptom in patients with carotid artery stenosis, we aimed to evaluate the effects of CEA/CAS on cerebral function in patients with carotid artery stenosis, using equilibrium function tests.

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Background: Endovascular treatment (EVT) for acute large vessel occlusion has proven to be effective in randomized controlled trials. We conducted a prospective cohort study to evaluate the real-world efficacy of EVT in a metropolitan area with a large number of comprehensive stroke centers and to compare it with the results of other registries and randomized controlled trials (RCTs).

Methods: We analyzed the Kanagawa Intravenous and Endovascular Treatment of Acute Ischemic Stroke registry, a prospective, multicenter observational study of patients treated by EVT and/or intravenous tissue-type plasminogen activator (tPA).

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Background And Objectives: Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).

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Article Synopsis
  • Recent studies showed a rise in cerebral venous thrombosis (CVT) cases during the COVID-19 pandemic, prompting this evaluation of hospitalization and mortality rates comparing the pandemic year (2020) to the year prior (2019).
  • A cross-sectional study analyzed data from 171 stroke centers worldwide, focusing on CVT admissions and associated mortality from January 2019 to May 2021, revealing no significant differences in overall CVT volume or mortality between 2019 and 2020.
  • However, the first five months of 2021 saw a notable increase in CVT admissions compared to 2019 and 2020, with higher mortality rates linked to COVID-19-positive patients and instances of vaccine-induced immune
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Background: During the COVID-19 pandemic, decreased volumes of stroke admissions and mechanical thrombectomy were reported. The study's objective was to examine whether subarachnoid haemorrhage (SAH) hospitalisations and ruptured aneurysm coiling interventions demonstrated similar declines.

Methods: We conducted a cross-sectional, retrospective, observational study across 6 continents, 37 countries and 140 comprehensive stroke centres.

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Objective: To measure the global impact of COVID-19 pandemic on volumes of IV thrombolysis (IVT), IVT transfers, and stroke hospitalizations over 4 months at the height of the pandemic (March 1 to June 30, 2020) compared with 2 control 4-month periods.

Methods: We conducted a cross-sectional, observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.

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Background: The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide.

Aims: We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy, stroke, and intracranial hemorrhage hospitalizations over a three-month period at the height of the pandemic (1 March-31 May 2020) compared with two control three-month periods (immediately preceding and one year prior).

Methods: Retrospective, observational, international study, across 6 continents, 40 countries, and 187 comprehensive stroke centers.

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Objective: Carotid artery stenosis and cerebral aneurism may have different platelet functions and antiplatelet responses because these diseases have different etiologies. In this study, we compared the antiplatelet loading effects prior to endovascular treatment between carotid artery stenosis and unruptured cerebral aneurysm (UCA) patients.

Methods: Nine patients with asymptomatic carotid artery stenosis (ACS), 14 with symptomatic carotid artery stenosis (SCS), and 20 with unruptured cerebral aneurysms were enrolled in this study.

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Article Synopsis
  • A case study is presented of an unusual connection between the external carotid artery (ECA) and the vertebrobasilar artery (VBA) that goes through the hypoglossal canal.
  • This connection is considered a variation of a persistent primitive hypoglossal artery but has unique features, including a shared origin with the occipital artery (OA).
  • The authors suggest renaming this anastomosis to "dilated primitive hypoglossal-proatlantal anastomosis" based on its anatomical characteristics.
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Background: In patients receiving chronic warfarin therapy, the international normalized ratio of prothrombin time (PT-INR) reportedly correlates with the incidence, size, severity, and outcome of ischemic stroke, and thus there are guidelines for the optimal PT-INR range that is to be maintained during secondary or primary prevention of ischemic stroke. However, the details of ischemic stroke in patients in whom an optimal PT-INR is maintained by warfarin therapy have not been thoroughly investigated. We conducted a retrospective study to determine the predictors of the size, severity, and outcome of ischemic stroke occurring in patients under chronic warfarin therapy and maintenance of an optimum PT-INR.

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The aim of this study was to analyze the pattern of magnetic resonance diffusion-weighted imaging (DWI) findings in status epilepticus in terms of clinical characteristics. Participants comprised 106 patients with status epilepticus who were admitted to our hospital and underwent DWI. Forty-five patients (42.

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Background And Purpose: Although ataxic hemiparesis is a common lacunar syndrome, the precise mechanism underlying hemiataxia is not clear. We attempted to identify ataxia-related, cerebral blood flow changes in patients presenting with ataxic hemiparesis after acute capsular infarct.

Methods: We used 99mTc-ECD brain perfusion single-photon emission computed tomography to evaluate regional cerebral blood flow in 12 patients with ataxic hemiparesis caused by capsular infarct, and we compared the regional blood flow of these patients with that of 11 patients with pure motor hemiparesis caused by similar lesions.

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We reported a 72-year-old man with thymoma who presented with hemichorea. Although his brain CT and MRI revealed no abnormality, regional cerebral blood flow changes, identified by single photon emission computed tomography, suggested that the mechanism underlying the chorea seemed to be a dysfunction of the subthalamic nucleus and pallidum. His hemichorea was completely resolved after thymectomy.

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A pseudo-subarachnoid hemorrhage (pseudo-SAH) is a brain computed tomography (CT) finding that is seen as high-density areas along the basal cisterns, the sylvian vallecula/fissure, the tentorium cerebella, or the cortical sulci, although no SAH is found upon lumbar puncture or at autopsy. There is one report of cryptococcal meningitis presenting as pseudo-SAH, but the explanatory pathology is unknown. A 68-year-old woman with headache, fever, decreased hearing, and decreased vision was admitted to our hospital.

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Background And Purpose: Supratentorial stroke can cause conjugate eye deviation directed contralateral to the affected side (wrong-way deviation). It is rare and thought to be associated exclusively with hemorrhagic stroke. We prospectively investigated the clinical features and prognostic significance of this wrong-way deviation.

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We report a 54-year-old man with right abducent nerve palsy, right facial nerve palsy, and left segmental sensory disturbance, which progressed for 2 weeks. He was found to have cavernous angioma in the lower pons. When he visited our hospital, he had right facial palsy, sensory disturbance of left half of the face and left upper limb, and diplopia.

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A-58-year old man presented with fluctuating ptosis and dysphagia. When he was 53 years old, he developed oral candidiasis and serum human immunodeficiency virus (HIV) RNA was detected. After starting highly active antiretroviral therapy, serum HIV RNA became undetectable.

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We report a case of terminal-stage small-cell lung cancer with multiple metastases in which postmortem computed tomography and magnetic resonance imaging (collectively called "autopsy imaging") were performed and correlated with conventional autopsy findings. In this case, autopsy imaging provided contemporaneous data that supported conventional autopsy findings. Autopsy imaging revealed the process of primary tumor growth, changes in metastatic lesions, and occurrences of new metastases in the terminal stage and made it easier to understand the clinical course of the patient.

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