Publications by authors named "Jae Sung Ahn"

In this study, we present lateral scanning white light interferometry (LS-WLI), where phase-shifting algorithms are applied to inspect the topography of a large field of view (FOV) with high-speed measurements. At a point, the interference signal must be acquired with a specific condition to adapt the phase-shifting algorithm. This means that all points have two points, of which the phase difference is π/2, when the number of points acquired in a phase period is multiple of 4, despite increasing the data points in a period.

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Cerebral revascularization for the treatment of atherosclerotic steno-occlusive disease (ASOD) was found to have no benefit compared with medical treatment. However, there is also criticism that with sufficiently long-term follow-up, a crossover might emerge demonstrating the advantages of surgery. Therefore, we examined the long-term outcome of cerebral revascularization performed on patients with carefully selected ASOD at our center.

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Aim: To share our clinical insights into octogenarian patients with unruptured intracranial aneurysms (UIAs) and evaluate the treatment strategies for this demographic.

Material And Methods: A retrospective analysis was conducted on data from 134 patients with a follow-up exceeding 6 months, all enrolled in this study. We assessed the incidence rates (IRs) of aneurysm growth and rupture, along with potential predictors of aneurysm growth.

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Ventriculoperitoneal shunt surgery was developed to manage excessive cerebrospinal fluid (CSF) in the brain's ventricles and is considered a mainstream treatment. Despite the development of the shunt device system, various complications still occur. In this study, we reported 307 cases and a long-term follow-up of at least five years of adult patients who underwent VP shunt surgery and analyzed various factors that may affect revision surgery.

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Background: This study evaluates the effectiveness of Therapeutic Hypothermia (TH) in treating poor-grade aneurysmal subarachnoid hemorrhage (SAH), focusing on functional outcomes, mortality, and complications such as vasospasm, delayed cerebral ischemia (DCI), and hydrocephalus.

Methods: Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a comprehensive literature search was conducted across multiple databases, including Medline, Embase, and Cochrane Central, up to November 2023. Nine studies involving 368 patients were selected based on eligibility criteria focusing on TH in poor-grade SAH patients.

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Transition metal dichalcogenides (TMDs) are promising candidates for ultrathin functional semiconductor devices. In particular, incorporating plasmonic nanoparticles into TMD-based devices enhances the light-matter interaction for increased absorption efficiency and enables control of device performance such as electronic, electrical, and optical properties. In this heterohybrid structure, manipulating the number of TMD layers and the aggregate size of plasmonic nanoparticles is a straightforward approach to tailoring device performance.

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Objective: Conus medullaris arteriovenous malformation (AVM) is rare and challenging to treat. To better define the presentation, prognosis, and optimal treatment of these lesions, the authors present their treatment experiences for conus medullaris AVM.

Methods: Eleven patients with AVM of the conus medullaris were identified between March 2013 and December 2021.

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Article Synopsis
  • Liver transplantation (LT) patients have a higher risk of neurological issues, prompting a study to analyze unruptured intracranial aneurysms (UIAs) and subarachnoid hemorrhage (SAH) occurrences around the LT procedure.
  • The study included 3,487 patients over a ten-year period, finding a 5.4% prevalence of UIAs and low incidences of SAH (0.5%) and hemorrhagic stroke (HS) (1.6%) within a year post-LT.
  • A new scoring system was developed to assess HS risk based on factors like mental status, UIA diagnosis, serum ammonia levels, and MELD scores, demonstrating strong predictive capabilities in identifying at-risk
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Objective: We evaluated the role of subgaleal closed suction drains in postoperative epidural hematoma (EDH) and wound complications following pterional craniotomy for cerebral aneurysm.

Methods: We reviewed 5,280 pterional craniotomies performed on 5,139 patients between January 2006 and December 2020. A drain was placed subgalealy and tip of drain was positioned between the bone flap and the deep temporalis.

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The emergence of infectious diseases worldwide necessitates rapid and precise diagnostics. Using gold nanoshells in the PCR mix, we harnessed their unique photothermal properties in the near-infrared regime to attain efficient heating, reaching ideal photothermal PCR cycle temperature profile. Our photothermal PCR method expedited DNA amplification while retaining its detection sensitivity.

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To investigate the association between chemical markers (triglyceride, C-reactive protein (CRP), and inflammation markers) and perfusion markers (relative cerebral vascular reserve (rCVR)) with moyamoya disease progression and complication types. A total of 314 patients diagnosed with moyamoya disease were included. Triglyceride and CRP levels were assessed and categorized based on Korean guidelines for dyslipidemia and CDC/AHA guidelines, respectively.

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Purpose: Flow-preservation bypass is a treatment option for complex intracranial aneurysms (IAs) that cannot be managed with microsurgical clipping or endovascular treatment. Various bypass methods are available, including interposition grafts such as the radial artery or saphenous vein. Size discrepancy, invasiveness, and procedure complexity must be considered when using interposition grafts.

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Hemangioblastomas (HBMs) are rare vascular tumors commonly located in the posterior fossa of adults. A mid-50s patient presented with sudden unconsciousness. Computed tomography scans revealed acute hemorrhages around the posterior fossa, predominantly in the subarachnoid space.

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Objective: The mass effect associated with large or giant intracranial aneurysms is difficult for traditional endovascular treatment. This study investigated whether flow diverters can relieve the aneurysmal mass effect caused by aneurysmal compression symptoms.

Methods: Fifty-five patients with unruptured large and giant intracranial aneurysms treated by a flow diverter at our institution from January 2014 to February 2022 were retrospectively evaluated.

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A metastatic brain tumor is the most common type of malignancy in the central nervous system, which is one of the leading causes of death in patients with lung cancer. The purpose of this study is to evaluate the efficacy of a novel treatment for metastatic brain tumors with lung cancer using neural stem cells (NSCs), which encode rabbit carboxylesterase (rCE) and the secretion form of tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL). rCE and/or sTRAIL were transduced in immortalized human fetal NSCs, HB1.

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Cognitive impairment refers to notable declines in cognitive abilities including memory, language, and emotional stability leading to the inability to accomplish essential activities of daily living. Astrocytes play an important role in cognitive function, and homeostasis of the astrocyte-neuron lactate shuttle (ANLS) system is essential for maintaining cognitive functions. Aquaporin-4 (AQP-4) is a water channel expressed in astrocytes and has been shown to be associated with various brain disorders, but the direct relationship between learning, memory, and AQP-4 is unclear.

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Background: Dural arteriovenous fistulas at the craniocervical junction (CCJ DAVFs) are a rare vascular disease. Endovascular treatment (EVT) and microsurgery are the primary treatment modalities for CCJ DAVFs. However, incomplete treatment or complications may occur after treatment because of the anatomical complexity.

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Background: In treating anterior choroidal artery (AChA) aneurysms, preserving the AChA main trunk is of course necessary to prevent postoperative ischemic complications. However, in practice, complete occlusions are often limited by small branches.

Objective: We aimed to demonstrate that even in cases where complete occlusion of the AChA aneurysm is complex due to small branches, complete occlusion can be safely achieved using indocyanine green video-angiography and intraoperative neurophysiological monitoring (IONM).

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Background: Subarachnoid hemorrhage (SAH) patients have oxidative stress results in inflammation, tissue degeneration and neuronal damage. These deleterious effects cause aggravation of the perihematomal edema (PHE), vasospasm, and even hydrocephalus. We hypothesized that antioxidants may have a neuroprotective role in acute aneurysmal SAH (aSAH) patients.

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Objective: Many neurosurgeons routinely perform postoperative intensive care unit (ICU) management after clipping of unruptured intracranial aneurysms (UIAs). However, whether routine postoperative ICU care is necessary remains a clinical question. Therefore, we investigated which factors acted as risk factors that actually required ICU care after microsurgical clipping of unruptured aneurysms.

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Article Synopsis
  • The study investigates whether the fetal-type posterior cerebral artery (FPCA) is a risk factor for the recurrence of coiled internal carotid artery incorporating posterior communicating artery (ICA-PCoA) aneurysms, which previous research has not conclusively proven.
  • Three analytical methods were employed: conventional statistical analysis of 95 patient cases, computational fluid dynamics (CFD) simulations to assess blood flow dynamics, and a random forest with hyper-ensemble approach (RF with HEA) for enhanced data evaluation.
  • Results from all three analyses indicate that FPCA does not significantly contribute to the recurrence of coiled ICA-PCoA aneurysms, suggesting that it is not a major risk factor compared to other elements like packing density.
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Objective: The aim of this study was to investigate the efficacy of intraoperative indocyanine green videoangiography (ICG-VA) and intraoperative neuromonitoring (IONM) to prevent postoperative ischemic complications during microsurgical clipping of unruptured anterior choroidal artery (AChA) aneurysms.

Methods: We retrospectively reviewed the clinical and radiological records of all patients who had undergone microsurgical clipping for unruptured AChA aneurysms at our institution between April 2001 and December 2019. We compared the postoperative complication rate of the group for which intraoperative ICG-VA and IONM were utilized (group B; n=324) with that of the group for which intraoperative ICG-VA and IONM were not utilized (group A; n=72).

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Purpose: An anterior communicating artery is a common location for both ruptured and unruptured intracranial aneurysms, and microsurgery is sometimes necessary for their successful treatment. However, postoperative infarction should be considered during clipping due to the complex surrounding structures of anterior communicating artery aneurysms. This study aimed to evaluate the risk factors of postoperative infarction after surgical clipping of unruptured anterior communicating artery aneurysms and its clinical outcomes.

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Background: Cerebral myxomatous aneurysms (CMA) are intracranial aneurysms caused by cardiac myxoma. The exact mechanism underlying their development has not yet been elucidated. And an optimal treatment method has not yet been established because of rarity of the disease.

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The understanding and engineering of the plasmon-exciton coupling are necessary to control the innovative optoelectronic device platform. In this study, we investigated the intertwined mechanism of each plasmon-exciton couplings in monolayer molybdenum disulfide (MoS) and plasmonic hybrid structure. The results of absorption, simulation, electrostatics, and emission spectra show that interaction between photoexcited carrier and exciton modes are successfully coupled by energy transfer and exciton recombination processes.

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