Horizontal contralateral approach for the distal anterior cerebral artery aneurysm: technical note

Background: The authors present a modified interhemispheric approach for the distal ACA aneurysm to resolve several problems including the narrow surgical corridor, the difficulty of proximal control, and the aneurysmal projection toward the surgeon. Methods: We refined the positions of the patient's head and the surgeon. The patient's head is fixed with flexion and tilted to the contralateral side. The surgeon sits on the contralateral side of the patient and not on the cranial side. Results: The present approach allows the surgeon to comfortably use both hands in the horizontal operative filed, to obtain a minimum retraction of the brain, and to easily secure the proximal artery. Conclusions: This modified interhemispheric approach is useful for a patient with the distal ACA aneurysm.ArticleSURGICAL NEUROLOGY. 72(1):65-68 (2009)journal articl

Outcome predictors of open embolectomy in middle cerebral artery occlusion

Objective: The purpose of this paper was to analyse the outcome of the patients with acute middle cerebral artery (MCA) occlusion treated by open embolectomy. Methods: A clinical chart review was retrospectively conducted for 30 patients who had MCA occlusion and were treated with open embolectomy. According to the Glasgow Outcome Scale, the patients' outcome at discharge is divided in two groups: favorable outcome (good recovery and moderate disability) or unfavorable outcome (severe disability, vegetative state and death). The following variables between the favorable and unfavorable outcomes were analysed: age, sex, Glasgow Coma Scale score on admission, affected side, occlusion site, occlusion time, atrial fibrillation on electrocardiogram, fibrinolysis, aphasia, hemiparesis and hemorrhagic infarction after surgery. Results: The outcomes of 30 patients were favorable in 16 patients (good recovery in nine and moderate disability in seven) and unfavorable in 14 patients (severe disability in 12, vegetative state in one and death in one). The M1 occlusion and fibrinolysis performance were more frequent in the unfavorable outcome group than in the favorable one. Logistic regression analysis with a stepwise method indicated that the only occlusion site was independently associated with the unfavorable outcome. The occlusion time >360 minutes was not the predictor of the unfavorable outcome. Discussion: The outcome of patients with MCA occlusion treated by the open embolectomy depends on the occlusion site and the fibrinolysis performance in the present study. The M1 occlusion is also the independent risk factor of the unfavorable outcome. However, the occlusion time itself has no relation to the unfavorable outcome. These results indicate that therapeutic time windows vary in individuals probably due to the collateral blood flow.ArticleNEUROLOGICAL RESEARCH. 31(9):892-894 (2009)journal articl

Emergency EC-IC bypass for symptomatic atherosclerotic ischemic stroke

Previous studies have shown that extracranial-intracranial (EC-IC) bypass surgery has no preventive effect on subsequent ipsilateral ischemic stroke in patients with symptomatic atherosclerotic internal carotid occlusion and hemodynamic cerebral ischemia. A few studies have assessed whether an urgent EC-IC bypass surgery is an effective treatment for main trunk stenosis or occlusion in acute stage. The authors retrospectively reviewed 58 consecutive patients who underwent urgent EC-IC bypass for symptomatic internal carotid artery or the middle cerebral artery stenosis or occlusion between January 2003 and December 2011. Clinical characteristics and neuroimagings were evaluated and analyzed. Based on preoperative angiogram, responsible lesions were the internal carotid artery in 19 (32.8 %) patients and the middle cerebral artery in 39 (67.2 %). No hemorrhagic complication occurred. Sixty-nine percent of patients showed improvement of neurological function after surgery, and 74.1 % of patients had favorable outcome. Unfavorable outcome was associated with insufficient collateral flow and new infarction after bypass surgery.ArticleNEUROSURGICAL REVIEW. 36(4):559-564 (2013)journal articl

Urgent open embolectomy for cardioembolic cervical internal carotid artery occlusion

Acute ischemic stroke attributable to cervical internal carotid artery (ICA) occlusion is frequently associated with severe disability or death and is usually caused by atherosclerosis. By contrast, the cardioembolic cervical ICA occlusion is rare, and feasibility of urgent recanalization remains unclear. We present the first study in the literature that focuses on urgent open embolectomy for the treatment of cardioembolic cervical ICA occlusion. A retrospective review of the charts for patients undergoing open embolectomy was performed. Between April 2006 and September 2007, 640 consecutive patients with acute ischemic stroke were treated. Of them, three patients (0.47%) with the acute complete cardioembolic cervical ICA occlusion underwent urgent open embolectomy. All patients presented with profound neurological deficits and atrial fibrillation. The urgent open embolectomy achieved complete recanalization in all patients without any complications. All emboli in three patients were very large and fibrinous in histological findings. Two of three patients showed rapid improvement in neurological functions after surgical treatments. The cardioembolic occlusion of the cervical ICA is rare, but its possibility should be considered in patients with acute ischemic stroke suffering profound neurological deficits and atrial fibrillation. Urgent open embolectomy may be a treatment option to obtain successful recanalization for cardioembolic cervical ICA occlusion and is recommended because it is technically easier and similar to carotid endarterectomy.ArticleNEUROSURGICAL REVIEW. 33(3):341-348 (2010)journal articl

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Emergency EC-IC bypass for symptomatic atherosclerotic ischemic stroke

Previous studies have shown that extracranial-intracranial (EC-IC) bypass surgery has no preventive effect on subsequent ipsilateral ischemic stroke in patients with symptomatic atherosclerotic internal carotid occlusion and hemodynamic cerebral ischemia. A few studies have assessed whether an urgent EC-IC bypass surgery is an effective treatment for main trunk stenosis or occlusion in acute stage. The authors retrospectively reviewed 58 consecutive patients who underwent urgent EC-IC bypass for symptomatic internal carotid artery or the middle cerebral artery stenosis or occlusion between January 2003 and December 2011. Clinical characteristics and neuroimagings were evaluated and analyzed. Based on preoperative angiogram, responsible lesions were the internal carotid artery in 19 (32.8 %) patients and the middle cerebral artery in 39 (67.2 %). No hemorrhagic complication occurred. Sixty-nine percent of patients showed improvement of neurological function after surgery, and 74.1 % of patients had favorable outcome. Unfavorable outcome was associated with insufficient collateral flow and new infarction after bypass surgery.ArticleNEUROSURGICAL REVIEW. 36(4):559-564 (2013)journal articl