Publications by authors named "Shinya Kohyama"

Background: Intra-and extracranial artery dissections are uncommon but significant causes of ischemic stroke and subarachnoid hemorrhage (SAH). While individual dissections are well-documented, simultaneous dissections of multiple vessels leading to both hemorrhagic and ischemic strokes are extremely rare.

Case Description: A 41-year-old man presented with acute onset of headache, vomiting, and loss of consciousness.

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Background And Objectives: Although carotid endarterectomy (CEA) and carotid artery stenting (CAS) reduce the risk of stroke, their efficacy in improving decreased vision is unclear. This study aims to evaluate the effects of CEA and CAS on ocular blood flow (OBF) and visual acuity (VA) in patients with carotid artery stenosis, while also exploring the possible relevance of postoperative microembolisms to visual recovery.

Methods: The results of 78 procedures (CEA, 39; CAS, 39) performed in 76 patients with carotid artery stenosis were prospectively analyzed.

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Article Synopsis
  • Dural arteriovenous fistula (dAVF) is typically treated with endovascular therapy, but this method has risks like embolic material migration and brain infarction.* -
  • A case involving a man with left hemiparesis revealed a successfully treated dAVF, but also resulted in complications such as subarachnoid hemorrhage post-treatment.* -
  • The case emphasizes the importance of careful preoperative assessments and thorough postoperative monitoring in managing dAVF, with a need for more research on unexplained complications.*
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  • Distal transradial access (dTRA) through the anatomical snuffbox offers benefits for endovascular treatments but faces challenges due to the small diameter of the radial artery affecting the use of balloon-guide catheters (BGCs).
  • A study involving 170 patients treated with sheathless dTRA using an 8Fr Optimo BGC found a radial artery occlusion (RAO) rate of 28%, with a significant correlation between smaller artery diameter and higher RAO risk.
  • The research suggests a threshold of 2.4 mm for radial artery diameter to predict RAO risk, indicating that careful evaluation of artery size is essential for choosing large-bore BGCs; further studies are needed for validation and
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  • This study evaluated the safety and effectiveness of the Versi Retriever for mechanical thrombectomy in patients suffering from acute ischemic stroke (AIS) at 10 hospitals in Japan.
  • It involved 58 patients, showing that 62% achieved a good recovery (mRS 0-2) after 90 days, and 100% had successful blood flow restoration.
  • The procedure had an 8% mortality rate within 90 days and a significant occurrence of intracranial hemorrhage, indicating that while effective, some risks are involved.
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  • Thromboembolism is a critical concern in patients undergoing endovascular treatment for ruptured cerebral aneurysms, and administering antiplatelet agents like aspirin before the procedure may lower this risk.
  • The study, called ASTOP, is a multicenter, randomized, double-blind trial involving 484 patients, comparing the effects of 200 mg of aspirin versus a placebo prior to treatment.
  • Primary outcomes will focus on measuring thromboembolic complications and ischemic lesions during the procedure, while secondary outcomes will assess cerebral ischemic events, bleeding incidents, and patient functional status after 90 days.
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Background: Various degrees of thrombosis have been reported in patients with giant aneurysms. However, small, unruptured aneurysms rarely resolve spontaneously. Herein, we report a case of a small unruptured aneurysm in the clinoid segment (C3) of the left internal carotid artery (ICA) that showed almost complete occlusion at the 1-year follow-up.

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Objective: Reperfusion therapy, such as intravenous tissue-plasminogen activator (IV-tPA) and mechanical thrombectomy (MT) for acute ischemic stroke, may increase the incidence of acute symptomatic seizure (ASS) and post-stroke epilepsy (PSE). This study aimed to analyze the effect and predictors of reperfusion therapy for ASS and PSE limited to large-vessel occlusions (LVOs).

Methods: This retrospective study classified 237 subjects with LVO into four groups: (1) IV-tPA + MT+ (n = 74 cases, (2) MT only (n = 82), (3) tissue-plasminogen activator (tPA) only (n = 28), and (4) IV-tPA - MT- (n = 53).

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Distal embolus due to mechanical thrombectomy is a frequent complication and directly results in a poor prognosis. Therefore, it is important to decrease distal embolus as much as possible in mechanical thrombectomy. EmboTrap III may be useful as a filter to prevent distal embolus in patients with a large volume of thrombus.

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Objective: Unruptured posterior communicating artery (Pcom) aneurysms cause oculomotor nerve palsy (ONP). However, the time course of recovery after aneurysm repair remains unclear. We aimed to evaluate the ONP course after clipping and coiling for unruptured Pcom aneurysms.

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An 85-year-old female with situs inversus totalis presented with right hemiplegia, right facial nerve palsy, eye deviation to the left, and aphasia. Magnetic resonance imaging revealed acute ischemic lesions in the left insular cortex and the frontal lobe. Magnetic resonance angiography revealed an occlusion of the left internal carotid artery.

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Background And Purpose: Reperfusion therapy is typically performed in cases with acute cerebral infarction. Mechanical thrombectomy (MT) achieves superior recanalization and favorable outcomes. However, some patients have poor functional prognosis despite successful recanalization.

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Following the implantation of a carotid artery stent (CAS), the aetiology of in-stent occlusion typically shifts from embolic events in the acute phase to intimal hyperplasia in the chronic phase. A man in his 70s with a history of CAS implantation (performed 5 years ago) for left internal carotid artery (ICA) stenosis was admitted to our hospital with a chief complaint of left-sided transient scotoma. MRI revealed an acute occlusion of the left ICA, and an urgent digital subtraction angiography (DSA) was performed.

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Article Synopsis
  • The case study describes the incidental finding of a fenestrated superior cerebellar artery (SCA) in a 65-year-old woman during a magnetic resonance angiography for unruptured cerebral aneurysms.
  • Along with the SCA fenestration, the imaging also revealed two unruptured aneurysms and other vascular variations, such as a left common carotid artery originating from the brachiocephalic trunk.
  • Due to the small size of the aneurysms, yearly observation was chosen as the treatment approach, highlighting that SCA fenestration is a rare anatomical variation, with this being only the second reported case identified via MR angiography in English literature.
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Background: Brain arteriovenous malformations (AVMs) usually manifest as hemorrhages or seizures. They rarely present with ischemic symptoms, especially in young patients. We present a case of an epileptogenic AVM that led to cerebral infarction due to paradoxical embolic occlusion of the middle cerebral artery (MCA) involving the main feeder of the lesion.

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  • * Data was collected from 20 patients treated between April 2022 and April 2023, with 11 patients using the new catheter system and a success rate of 90.9%, showing no complications like radial artery occlusion.
  • * Key anatomical factors such as the entry angle of the target vessel and the diameter of the proximal parent artery were found to be crucial for selecting suitable patients, enhancing the effectiveness of the aneurysm treatment.
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Essential thrombocythemia is a myeloproliferative neoplasm. Ischemic stroke is frequently the first manifestation of essential thrombocythemia. We herein report a patient with JAK2V617 mutation-positive essential thrombocythemia who developed recurrent ischemic stroke with rapid development of intracranial artery stenosis and subsequently underwent successful mechanical thrombectomy.

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Background: Delayed aneurysm rupture after flow-redirection endoluminal device (FRED) implantation is rare. We report a case of internal carotid-cavernous fistula (CCF) caused by a delayed aneurysm rupture of the cavernous portion of the internal carotid artery (ICA) after FRED implantation.

Case Description: A 75-year-old woman had a gradually enlarging aneurysm at the C4 portion of the left ICA.

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Background: A vertebral artery-anterior spinal artery (VA-ASA) aneurysm is very rare. The authors report a case of successful coil embolization of a ruptured aneurysm of the VA-ASA.

Observations: A 54-year-old man with World Federation of Neurosurgical Societies grade II subarachnoid hemorrhage presented with an aneurysm located at the region involving the origin of ASA on the VA.

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