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1.  Retrograde Stent Placement for Coil Embolization of a Wide-Necked Posterior Inferior Cerebellar Artery Aneurysm 
Korean Journal of Radiology  2012;13(4):510-514.
Wide-necked aneurysms of the posterior inferior cerebellar artery (PICA) are infrequently encountered in cerebrovascular practice, and endovascular treatment is difficult or impossible even with the use of several neck remodeling techniques. We present the case of a patient with a wide-necked aneurysm of the PICA, which was treated by the retrograde stenting through the contralateral vertebral artery and vertebrobasilar junction with antegrade coil embolization.
PMCID: PMC3384836  PMID: 22778576
Posterior inferior cerebellar artery; Aneurysm; Endovascular treatment; Retrograde stenting; Enterprise stent
2.  Enhanced Efficacy of Human Brain-Derived Neural Stem Cells by Transplantation of Cell Aggregates in a Rat Model of Parkinson's Disease 
Neural tissue transplantation has been a promising strategy for the treatment of Parkinson's disease (PD). However, transplantation has the disadvantages of low-cell survival and/or development of dyskinesia. Transplantation of cell aggregates has the potential to overcome these problems, because the cells can extend their axons into the host brain and establish synaptic connections with host neurons. In this present study, aggregates of human brain-derived neural stem cells (HB-NSC) were transplanted into a PD animal model and compared to previous report on transplantation of single-cell suspensions.
Rats received an injection of 6-OHDA into the right medial forebrain bundle to generate the PD model and followed by injections of PBS only, or HB-NSC aggregates in PBS into the ipsilateral striatum. Behavioral tests, multitracer (2-deoxy-2-[18F]-fluoro-D-glucose ([18F]-FDG) and [18F]-N-(3-fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl)nortropane ([18F]-FP-CIT) microPET scans, as well as immunohistochemical (IHC) and immunofluorescent (IF) staining were conducted to evaluate the results.
The stepping test showed significant improvement of contralateral forelimb control in the HB-NSC group from 6-10 weeks compared to the control group (p<0.05). [18F]-FP-CIT microPET at 10 weeks posttransplantation demonstrated a significant increase in uptake in the HB-NSC group compared to pretransplantation (p<0.05). In IHC and IF staining, tyrosine hydroxylase and human β2 microglobulin (a human cell marker) positive cells were visualized at the transplant site.
These results suggest that the HB-NSC aggregates can survive in the striatum and exert therapeutic effects in a PD model by secreting dopamine.
PMCID: PMC4272995  PMID: 25535514
Parkinson's disease; Cell transplantation; Human brain-derived neural stem cells; Cell aggregates; Rat model; [18F]-FP-CIT microPET
3.  Clinical Characteristics of Cerebral Venous Thrombosis in a Single Center in Korea 
The purpose of this study is to investigate the clinical characteristics of cerebral venous thrombosis (CVT) in a single center in Korea.
A total of 36 patients were diagnosed with CVT from August 2005 to May 2013. The patient data regarding age, sex, disease stage, pathogenesis, location, laboratory findings, radiological findings, and treatment modalities were retrospectively collected. The results were compared with those of previous studies in other countries.
The patient group comprised 21 men and 15 women with a mean age of 46.9 years (ranging from three months to 77 years). The most common cause was a prothrombotic condition (8 patients, 22.2%). Within the patient group, 13 patients (36.1%) had a hemorrhagic infarction, whereas 23 (63.9%) had a venous infarction without hemorrhage. By location, the incidence of hemorrhagic infarction was the highest in the group with a transverse and/or sigmoid sinus thrombosis (n=9); however, the proportion of hemorrhagic infarction was higher in the cortical venous thrombosis group (75%) and the deep venous thrombosis group (100%). By pathogenesis, the incidence of hemorrhagic infarction was the highest in the prothrombotic group (n=6), which was statistically significant (p=0.016).
According to this study, CVT was more prevalent in men, and the peak age group comprised patients in the sixth decade. The most common cause was a prothrombotic condition. This finding was comparable with reports from Europe or America, in which CVT was more common in younger women. Hemorrhagic infarction was more common in the prothrombotic group (p=0.016) than in the non-prothrombotic group in this study.
PMCID: PMC4219185  PMID: 25371777
Cerebral venous thrombosis; Hemorrhagic infarction; Prothrombotic condition
4.  Post-carotid stenting reperfusion injury with blood–brain barrier disruption on gadolinium-enhanced FLAIR MRI 
BMC Neurology  2014;14(1):178.
Following carotid revascularization, an abrupt increase in cerebral blood flow may disrupt the blood–brain barrier, resulting in reperfusion injury. This damage to the blood–brain barrier may be reflected by subarachnoid enhancement on FLAIR MRI after gadolinium injection.
Case presentation
The authors present two cases of post-carotid stenting reperfusion injury that showed hyperintensity in the subarachnoid spaces on FLAIR MRI after gadolinium injection.
These MRI findings may represent a marker for reperfusion injury after carotid revascularization.
PMCID: PMC4174251  PMID: 25204402
Reperfusion injury; Carotid stenting; Blood–brain barrier; MRI
5.  Glomus Tumor in the Femoral Nerve 
The glomus tumor of the peripheral nerve is one of the mesenchymal tumors originating in the epineurium, and is extremely rare. A 56-year-old man presented complaining of lancinating pain on the left thigh, which was provoked by pressure or exercise. Subsequent image study revealed a mass in the femoral nerve. Total surgical excision with the aid of intraoperative ultrasonography was performed and the pain was successfully controlled. The authors report an unusual case of a patient diagnosed with glomus tumor in peripheral nerve, with a review of the clinical features, imaging, and pathological findings.
PMCID: PMC3921288  PMID: 24527203
Glomus tumor; Peripheral nerve; Femoral nerve
6.  Long-term outcome of vertebral artery origin stenosis in patients with acute ischemic stroke 
BMC Neurology  2013;13:171.
Vertebral artery origin (VAO) stenosis is occasionally observed in patients who have acute ischemic stroke. We investigated the long-term outcomes and clinical significance of VAO stenosis in patients with acute ischemic stroke.
We performed a prospective observational study using a single stroke center registry to investigate the risk of recurrent stroke and vascular outcomes in patients with acute ischemic stroke and VAO stenosis. To relate the clinical significance of VAO stenosis to the vascular territory of the index stroke, patients were classified into an asymptomatic VAO stenosis group and a symptomatic VAO stenosis group.
Of the 774 patients who had acute ischemic stroke, 149 (19.3%) of them had more than 50% stenosis of the VAO. During 309 patient-years of follow-up (mean, 2.3 years), there were 7 ischemic strokes, 6 hemorrhagic strokes, and 2 unknown strokes. The annual event rates were 0.97% for posterior circulation ischemic stroke, 4.86% for all stroke, and 6.80% for the composite cardiovascular outcome. The annual event rate for ischemic stroke in the posterior circulation was significantly higher in patients who had symptomatic VAO stenosis than in patients who had asymptomatic stenosis (1.88% vs. 0%, p = 0.046). In a multivariate analysis, the hazard ratio, per one point increase of the Essen Stroke Risk Score (ESRS) for the composite cardiovascular outcome, was 1.46 (95% CI, 1.02-2.08, p = 0.036).
Long-term outcomes of more than 50% stenosis of the VAO in patients with acute ischemic stroke were generally favorable. Additionally, ESRS was a predictor for the composite cardiovascular outcome. Asymptomatic VAO stenosis may not be a specific risk factor for recurrent ischemic stroke in the posterior circulation. However, VAO stenosis may require more clinical attention as a potential source of recurrent stroke when VAO stenosis is observed in patients who have concurrent ischemic stroke in the posterior circulation.
PMCID: PMC3833629  PMID: 24215371
7.  Galeal Tack-Up Sutures to Prevent Subgaleal Cerebrospinal Fluid Collection 
Postoperative subgaleal cerebrospinal fluid (CSF) collection is considered as one of the common minor surgical complication which can lead to prolonged hospitalization. We introduce "galeal tack-up suture" to prevent postoperative subgaleal CSF collection.
Galeal tack-up suture consists of various surgical techniques which aim to fix galea to cranium in order to prevent CSF pooling in subgaleal space. A total of 87 patients who underwent craniotomy were divided into two groups while closing the wound : group A with galeal tack-up suture and group B with routine wound closure without galeal tack-up suture. The patients were observed for postoperative subgaleal CSF collection.
Among 87 cranitomy cases, galeal tack-up suture was performed in 32 cases and routine wound closure was done in 55 cases. Postoperative subgaleal CSF collection occurred in 13 cases (15%) in which 12 cases occurred in group B patients and 1 case occurred in group A patients (p=0.026).
Galeal tack-up suture is an easy and effective technique in wound closure to prevent postoperative CSF collection.
PMCID: PMC3841277  PMID: 24294458
Cerebrospinal fluid leak; Craniotomy; Scalp; Sutures
8.  Comparative Results of the Patients with Intracerebral and Intra-sylvian Hematoma in Ruptured Middle Cerebral Artery Aneurysms 
To clarify the prognosis of the patients with intra-sylvian hematoma (ISH) and intracerebral hematoma (ICH) in ruptured middle cerebral artery (MCA) aneurysms.
We categorized hematoma into ISH and ICH by the presence of intra-hematomal contrast enhancing vessel (IHCEV) on computed tomography angiography (CTA). Forty-four ruptured MCA aneurysm patients with ICH or ISH were grouped by the grading system proposed by the authors in our previous study. We investigated the relevance of the following factors: patient's age, gender, Hunt-Hess grade, Glasgow outcome scale (GOS) and changes in Glasgow coma scale (GCS) between pre-operation and 7 days after operation.
There were no significant differences statistically in age, gender, Hunt-Hess grade, and GOS between the ISH and ICH groups. In their peri-operative GCS change, the ICH group showed greater improvement compared to the ISH group (p = 0.0391). The hematoma grade had a significant relevance with the patients' GOS.
Although there were no significant statistic differences in the GOS of the 2 hematoma groups, there were prominent improvements of post-operative GCS in the ICH group. Unlike in the ISH group, effective removal of hematoma was possible in most patients of the ICH group. Thus although there is no difference in the prognosis of the 2 groups, early surgical evacuation of hematoma seems to be effective in improving the short-term GCS score in peri-operative period.
PMCID: PMC3804658  PMID: 24167800
Intracerebral hematoma; Cerebral aneurysm; Middle cerebral artery
9.  Risk factors predicting the new symptomatic vertebral compression fractures after percutaneous vertebroplasty or kyphoplasty 
European Spine Journal  2011;21(5):905-911.
Percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) are effective procedures to alleviate pain caused by osteoporotic vertebral compression fractures (VCFs). New vertebral compression fracture (NVCF) has been noted as a potential late sequela of the procedures. The incidence of NVCFs and affecting risk factors were investigated.
Materials and methods
The authors retrospectively analyzed the occurrence of NVCFs in 147 patients treated with PVP or PKP for osteoporotic VCFs. Possible risk factors, such as age, gender, body mass index, bone mineral density (BMD), location of treated vertebra, treatment modality, amount of bone cement injected, anterior–posterior ratio of the fractured vertebra, cement leakage into the disc space, and pattern of cement distribution, were assessed.
Twenty-seven patients (18.4%) had subsequent symptomatic NVCFs with a median time to new fracture was of 70 days. The 1-year symptomatic fracture-free rate was 85.0% by the Kaplan–Meier estimate. Eighteen (66.7%) of the 27 patients had an NVCF on the adjacent vertebra. Significant differences (P < 0.05) were found between the NVCF and control groups in regard to age, treatment modality, BMD, and the proportion of cement leakage into the disc space. Discal cement leakage and low BMD affected on adjacent NVCFs.
The most important risk factors affecting NVCFs were osteoporosis and intervertebral discal cement leakage.
PMCID: PMC3337901  PMID: 22160212
Osteoporotic compression fracture; Vertebroplasty; Kyphoplasty; BMD; Discal leakage
10.  Eosinophilic Myelitis in the Cervical Cord Mimicking Intramedullary Cord Tumor 
Eosinophilic myelitis (EM) or atopic myelitis is a rare disease characterized by a myelitic condition in the spinal cord combined with allergic process. This disease has specific features of elevated serum IgE level, active reaction to mite specific antigen and stepwise progression of mostly the sensory symptoms. Toxocariasis can be related with a form of EM. This report describes two cases of cervical eosinophilic myelitis initially considered as intramedullary tumors. When a differential diagnosis of the intramedullary spinal cord lesion is in doubt, evaluation for eosinophilic myelitis and toxocariasis would be beneficial.
PMCID: PMC3488654  PMID: 23133734
Allergy; Eosinophilic myelitis; Intramedullary tumor; Toxocariasis
11.  Grading of Intracerebral Hemorrhage in Ruptured Middle Cerebral Artery Aneurysms 
To propose grading of intracerebral hemorrhage (ICH) in ruptured middle cerebral artery (MCA) aneurysms, which helps to predict the prognosis more accurately.
From August 2005 to December 2010, 27 cases of emergent hematoma evacuation and aneurysm clipping for MCA aneurysms were done in the author's clinic. Three variables were considered in grading the ICH, which were 1) hematoma volume, 2) diffuse subarachnoid hemorrhage (SAH) that extends to the contralateral sylvian cistern, and 3) the presence of midline shifting from computed tomography findings. For hematoma volume of greater than 25 mL, we assigned 2 points whereas 1 point for less than 25 cc. We also assigned 1 point for the presence of diffuse SAH whereas 0 point for the absence of it. Then, 1 point was assigned for midline shifting of greater than 5 mm whereas 0 point for less than 5 mm.
According to the grading system, the numbers of patients from grade 1 to 4 were 4, 6, 8 and 9 respectively and 5, 7, 8, 4 and 3 patients belonged to Glasgow Outcome Scale (GOS) 5 to 1 respectively. It was found that the patients with higher GOS had lower ICH grade which were confirmed to be statistically significant (p<0.01). Preoperative Hunt and Hess grade and absence of midline shifting were the factors to predict favorable outcome.
The ICH grading system composed of above three variables was helpful in predicting the patient's outcome more accurately.
PMCID: PMC3393860  PMID: 22792422
Subarachnoid hemorrhage; Middle cerebral artery aneurysm; Intracerebral hemorrhage
12.  Serial Expression of Hypoxia Inducible Factor-1α and Neuronal Apoptosis in Hippocampus of Rats with Chronic Ischemic Brain 
The purpose of this study is to investigate serial changes of hypoxia-inducible factor 1α (HIF-1α), as a key regulator of hypoxic ischemia, and apoptosis of hippocampus induced by bilateral carotid arteries occlusion (BCAO) in rats.
Adult male Wistar rats were subjected to the permanent BCAO. The time points studied were 1, 2, 4, 8, and 12 weeks after occlusions, with n=6 animals subjected to BCAO, and n=2 to sham operation at each time point, and brains were fixed by intracardiac perfusion fixation with 4% neutral-buffered praraformaldehyde for brain section preparation. Immunohistochemistry (IHC), western blot and terminal uridine deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed to evaluate HIF-1α expression and apoptosis.
In IHC and western blot, HIF-1α levels were found to reach the peak at the 2nd week in the hippocampus, while apoptotic neurons, in TUNEL assay, were maximal at the 4th week in the hippocampus, especially in the cornu ammonis 1 (CA1) region. HIF-1α levels and apoptosis were found to fluctuate during the time course.
This study showed that BCAO induces acute ischemic responses for about 4 weeks then chronic ischemia in the hippocampus. These in vivo data are the first to show the temporal sequence of apoptosis and HIF-1α expression.
PMCID: PMC3272506  PMID: 22323932
Bilateral carotid artery occlusion; Hippocampus; Hypoxic ischemia; Hypoxia-inducible factor 1α; Apoptosis
13.  Time-Resolved 3D Contrast-Enhanced MRA on 3.0T: a Non-Invasive Follow-Up Technique after Stent-Assisted Coil Embolization of the Intracranial Aneurysm 
Korean Journal of Radiology  2011;12(6):662-670.
To evaluate the usefulness of time-resolved contrast enhanced magnetic resonance angiography (4D MRA) after stent-assisted coil embolization by comparing it with time of flight (TOF)-MRA.
Materials and Methods
TOF-MRA and 4D MRA were obtained by 3T MRI in 26 patients treated with stent-assisted coil embolization (Enterprise:Neuroform = 7:19). The qualities of the MRA were rated on a graded scale of 0 to 4. We classified completeness of endovascular treatment into three categories. The degree of quality of visualization of the stented artery was compared between TOF and 4D MRA by the Wilcoxon signed rank test. We used the Mann-Whitney U test for comparing the quality of the visualization of the stented artery according to the stent type in each MRA method.
The quality in terms of the visualization of the stented arteries in 4D MRA was significantly superior to that in 3D TOF-MRA, regardless of type of the stent (p < 0.001). The quality of the arteries which were stented with Neuroform was superior to that of the arteries stented with Enterprise in 3D TOF (p < 0.001) and 4D MRA (p = 0.008), respectively.
4D MRA provides a higher quality view of the stented parent arteries when compared with TOF.
PMCID: PMC3194769  PMID: 22043147
Aneurysm; Coil embolization; Stent; Time of flight MRA; Time-resolved MRA
14.  Optimization of MR Parameters of 3D TOF-MRA for Various Intracranial Stents at 3.0T MRI 
Neurointervention  2011;6(2):71-77.
The in-stent signal reduction of the stented artery caused by susceptibility artifact or radiofrequency shielding artifact limited the use of time-of-flight MR angiography (TOF-MRA) as a follow-up tool after intracranial stenting. We showed the degree of an artifact according to different stent types, and optimized MR parameters for TOF-MRA in patients with intracranial stent on 3.0 T MRI.
Materials and Methods
Four stents (Neuroform, Wingspan, Solitaire, and Enterprise) were placed in a vascular flow phantom and imaged by changing flip angle (FA; 20°,30°,40°,50° and 60°) and bandwidth (BW; 31, 42 and 62.5 KHz) using TOF-MRA. Source data of each image set with different FA and BW were reconstructed with the maximal intensity projection (MIP) technique, and MIP images were used to evaluate the in-stent signal reduction of each stent according to the change of MR parameters. The in-stent signal reduction was assessed by calculating the relative in-stent signal (RIS) inside the stent as compared with background and signal intensity of the tube outside the stent. The optimal FA and BW of each stent were determined by comparing the RIS in each stent by one-sample t test. Finally, one neuroradiologist chose one image set with the best image quality.
The mean RIS for Neuroform, Wingspan, Solitaire and Enterprise stent was 66.3 ± 6.0, 44.2 ± 5.8, 22.8 ± 3.3 and 8.2 ± 2.9, respectively. The significantly high RIS of each stent was obtained with FA/BW value of 20°/31 KHz (Neuroform), 20°/31 KHz and 30°/42 KHz (Wingspan), 40°/42 KHz and 50°/31 KHz (Solitaire) and 40°/31 KHz and 50°/31 KHz (Enterprise). Among these MIP images with significantly high RIS, images with FA/BW value of 20°/31 KHz (Neuroform and Wingspan) and 50°/31 KHz (Solitaire and Enterprise) had the best image quality.
The degree of artifact was variable according to the design of each intracranial stent. The luminal visualization of closed-cell design stents such as Solitaire and Enterprise can be improved by higher FA. Thus, MR parameter should be adjusted according to the type of intracranial stents.
PMCID: PMC3214815  PMID: 22125752
Magnetic resonance imaging; Magnetic resonance angiography; Artifacts; Stents

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