Chang Wan Oh

Stroke Statistics in Korea: Part I. Epidemiology and Risk Factors: A Report from the Korean Stroke Society and Clinical Research Center for Stroke

The aim of the Part I of Stroke Statistics in Korea is to summarize nationally representative data of the epidemiology and risk factors of stroke in a single document. Every year, approximately 105,000 people experience a new or recurrent stroke and more than 26,000 die of stroke, which indicates that every 5 minutes stroke attacks someone and every 20 minutes stroke kills someone in Korea. Stroke accounts for roughly 1 of every 10 deaths. The estimated stroke prevalence is about 795,000 in people aged ≥30 years. The nationwide total cost for stroke care was 3,737 billion Korean won (US

Clinical characteristics of dural arteriovenous fistula

3.3 billion) in 2005. Fortunately, the annual stroke mortality rate decreased substantially by 28.3% during the first decade of the 21th century (53.2/100,000 in 2010). Among OECD countries, Korea had the lowest in-hospital 30-day case-fatality rate for ischemic stroke and ranked third lowest for hemorrhagic stroke in 2009. The proportion of ischemic stroke has steadily increased and accounted for 76% of all strokes in 2009. According to hospital registry studies, the 90-day mortality rate was 3-7% for ischemic stroke and 17% for intracerebral hemorrhage. For risk factors, among Korean adults ≥30 years of age, one in 3-4 has hypertension, one in 10 diabetes, and one in 7 hypercholesterolemia. One in 3 Korean adults ≥19 years of age is obese. Over the last 10 years, the prevalence of hypertension slightly decreased, but the prevalence of diabetes, hypercholesterolemia, and obesity increased. Smoking prevalence in men has decreased, but is still as high as 48%. This report could be a valuable resource for establishing health care policy and guiding future research directions.

Transient Hyperperfusion after Superficial Temporal Artery/Middle Cerebral Artery Bypass Surgery as a Possible Cause of Postoperative Transient Neurological Deterioration

Intracranial dural arteriovenous fistula (DAVF) is an uncommon neurosurgical condition; in particular, it has been infrequently reported in Korea. To understand the general clinical characteristics of DAVFs, the authors reviewed 53 cases and analyzed factors affecting DAVF hemorrhage of and treatment outcome. Since 1980 we have encountered 480 pial and 53 DAVFs, a ratio of 9.1 to 1. The age of these patients ranged from 1 month to 71 years, the most common being in the 6th decade, and females exceeded males by 1.65 to 1. All lesions except three were single, and symptoms were related to location and the venous drainage pattern. The most common location was the cavernous sinus, accounting for about 64% of cases, with the result that the most common clinical symptoms of DAVFs were ocular, namely proptosis and chemosis. The next was tinnitus also found in transverse-sigmoid sinus DAVFs. Intracranial hemorrhage was seen in eight cases,(15%) the primary cause of hemorrhage was retrograde intracranial venous drainage (P=0.017), and one hemorrhage was observed in cases with no intracranial venous drainage. Intracranial hemorrhage was more frequently in transverse-sigmoid than cavernous sinus DAVFs (P=0.049), and this proved to be so even where there was intracranial venous drainage. However, two of 34 patients with cavernous DAVFs became blind in one eye, demonstrating that in such patients, the clinical course could be aggressive. Thirteen patients were treated conservatively. The conservative treatment group was comprised of 13 patients, two of three patients with transverse-sigmoid sinus DAVF expired, and 7 of 10 with cavernous sinus DAVF experienced a clinical improvement or cure. Surgical excision was performed in only two patients. A total of 39 patients underwent embolization; clinical cure was achieved in 13, improvement of symptoms in 12, an unchanged or aggravated result occurred in 9, one died, and four were lost to follow up. During intervention, there was one hemorrhagic complication, owing to obstruction of the venous outflow with embolic materials. In this study, the most common location of DAVFs was the cavernous sinus. The cortical venous drainage remains the primary determinant of intracranial hemorrhage. Common indications for treatment include hemorrhage and neurological deficit. Endovascular treatment is preferred in the majority of cases except tentorial DAVF. The goal of embolization in cavernous DAVF is the alleviation of symptoms, not angiographic cure. But transverse-sigmoid sinus DAVF with venous restriction and leptomeningeal drainage should be treated aggressively.

Endovascular Coil Embolization of 435 Small Asymptomatic Unruptured Intracranial Aneurysms: Procedural Morbidity and Patient Outcome

Background: This study was designed to investigate the relationship between transient neurological deterioration and changes in cerebral perfusion after superficial temporal artery/middle cerebral artery (STA-MCA) bypass. Methods: Clinical characteristics of the patients with postoperative transient neurological deterioration were analyzed in 120 STA-MCA bypass procedures for ischemic cerebral diseases, such as atherosclerotic disease and moyamoya disease. Serial brain single-photon emission computed tomography (SPECT) was performed on 25 patients before surgery and on the third and tenth postoperative days. The hemispheric perfusion on SPECT was calculated semi-quantitatively using statistical parametric mapping and a probabilistic brain atlas. Results: Among 120 procedures, there were 4 permanent postoperative neurological deficits (3.3%) and 20 postoperative transient neurologic deteriorations with unknown etiology (17%). In 25 patients analyzed for postoperative perfusion changes, cerebral perfusion increased on the third postoperative day and the increased perfusion negatively correlated with preoperative perfusion (correlation coefficient = –0.77; p < 0.001). Temporal changes and the location of transient hyperperfusion on SPECT correlated with the time course and neurological deficits associated with postoperative transient neurological deterioration in 3 patients. Conclusions: Postoperative transient relative hyperperfusion is a common phenomenon and may be one of the causes of postoperative transient neurological deterioration after STA-MCA bypass surgery for ischemic cerebral diseases.

Induction of a senescence-like phenotype in bovine aortic endothelial cells by ionizing radiation

BACKGROUND AND PURPOSE: Whether treatment of small asymptomatic aneurysms is appropriate or not remains controversial. We performed a retrospective study on the procedural morbidity and mortality of coil embolization of small asymptomatic unruptured intracranial aneurysms (UIAs) to obtain a more generalized estimate of procedural risk. MATERIALS AND METHODS: A total of 435 small (maximum diameter ≤7 mm) asymptomatic UIAs in 370 patients were treated by coil embolization. Aneurysm sizes were determined by using 3D angiograms. We assessed procedure-related morbidity and mortality, immediate postprocedural angiographic results, short-term imaging follow-up results, and clinical outcomes. RESULTS: Initial aneurysm occlusion was complete in 334 aneurysms, near complete in 78, and incomplete in 22. One internal carotid artery (ICA) aneurysm that ruptured during the procedure was treated with parent artery occlusion. Two hundred wide-neck aneurysms were coiled with the aid of various neck-remodeling techniques. The 44 procedure-related complications were the following: 24 thromboembolisms, 11 coil protrusions or prolapses into the parent vessel, 4 intraprocedural ruptures, 3 device-related complications, and 2 femoral-access complications. We had a total of 44 (10.1%) procedure-related complications with only 1 leading to persistent neurologic deficit. Procedure-related permanent morbidity and mortality were 0.27% (1/370) and 0%, respectively. CONCLUSIONS: In this series of small unruptured asymptomatic aneurysms, endovascular treatment was achieved with good short-term angiographic outcome and low permanent neurologic impairment. The goal of this study was not to provide a conclusion about treatment guidelines for small UIA but rather to help guide future recommendations by presenting a more generalized estimate of endovascular treatment risk than is currently available.

Thromboembolic complications of elective coil embolization of unruptured aneurysms: the effect of oral antiplatelet preparation on periprocedural thromboembolic complication.

Abstract Oh, C-W., Bump, E. A., Kim, J-S., Janigro, D. and Mayberg, M. R. Induction of a Senescence-Like Phenotype in Bovine Aortic Endothelial Cells by Ionizing Radiation. Radiat. Res. 156, 232–240 (2001). Treatment of confluent monolayers of bovine aortic endothelial cells (BAEC) with γ rays resulted in the delayed appearance of cells with an enlarged surface area that were morphologically similar to senescent cells. The majority of these cells stained positively for senescence-associated β-galactosidase (SA-β-gal), indicating that these cells are biochemically similar to senescent cells. The incidence of the senescence-like phenotype increased with dose (5–15 Gy) and time after irradiation. Cells with a senescence-like phenotype began to appear in the monolayer several days after irradiation. The onset of the appearance of this phenotype was accelerated by subculturing 24 h after irradiation. This acceleration was not entirely due to stimulation of progression through the cell cycle, since a high percentage of the senescent-like cells that appeared after subculture were not labeled with BrdUrd during the period after subculture. Prolonged up-regulation of expression of CDKN1A (also known as p21CIP1/WAF1) after irradiation was noted by Western blot analysis, again suggesting a similarity to natural senescence. Phenotypically altered endothelial cells were present in the irradiated monolayers as long as 20 weeks after irradiation, suggesting that a subpopulation of altered endothelial cells that might be functionally deficient could persist in the vasculature of irradiated tissue for a prolonged period after irradiation.

The Significance of Blood Pressure Variability for the Development of Hemorrhagic Transformation in Acute Ischemic Stroke

OBJECTIVEWe retrospectively evaluated whether antiplatelet preparation lowered the thromboembolic complication rate during the perioperative period. METHODSWe reviewed 328 elective coil embolization procedures in which only microcatheters were used for coiling. No antiplatelet medication was prescribed before the procedure in 95 cases (29%, group 1), whereas antiplatelet therapy was used in 233 cases (71%, group 2; 61 [18.6%] with a single agent [aspirin or clopidogrel] and 172 [52.4%] with both agents). Antiplatelet agents were not given after coiling unless atherosclerosis, severe coil protrusion, or a thromboembolic complication occurred during the procedure. A thromboembolic complication was defined as a procedural thromboembolic event or transient ischemic attack or stroke occurring within 2 days of embolization. RESULTSThromboembolic complications occurred in 11 cases (3.4%): 6 (6.3%) in group 1 and 5 (2.1%) in group 2 (P = .085). In 195 cases (59.5%) treated by the single microcatheter technique, the risk of thromboembolic complications was low and not affected by antiplatelet preparation (1.8% [no preparation] vs 2.2% [preparation]; P = 1.000). However, in 133 cases (40.5%) treated by the multiple microcatheter technique, antiplatelet preparation significantly reduced the thromboembolic complication risk by 85.2% (12.8% [no preparation] vs 2.1% [preparation]; odds ratio, 0.148; 95% confidence interval, 0.027–0.798; P = .023). The aneurysms treated by the multiple microcatheter technique had more complex configurations for coiling (P < .001). The risk of hemorrhage was not increased by antiplatelet preparation (P = .171). CONCLUSIONAntiplatelet preparation lowered the periprocedural thromboembolic complication rate in unruptured aneurysms treated by the multiple microcatheter technique and did not increase the risk of hemorrhage. Therefore, antiplatelet preparation can help to reduce complications in patients in whom technical difficulties are expected without the risk of hemorrhage.

Moyamoya disease in adults: characteristics of clinical presentation and outcome after encephalo-duro-arterio-synangiosis

Background and Purpose— Elevated blood pressure (BP) is commonly observed in acute ischemic stroke and is known to be associated with hemorrhagic transformation (HT). However, the effect of BP variability on the development of HT is not known well. Methods— A consecutive series of patients with acute ischemic stroke, who were hospitalized within 24 hours of onset and showed no HT on initial gradient echo MRI, were enrolled in this study. BP measurements during the first 72 hours were obtained, and BP variability of each patient was described using various summary parameters: SD, maximum (max), minimum (min), difference between max and min (max−min), average squared difference between successive measurements (sv), and maximum sv (svmax). Results— Of 792 patients meeting the eligibility criteria, 70 (8.8%) developed HT. Among BP variability parameters categorized into quartiles, SBPmax, SBPmin, SBPmax−min, SBPsvmax, DBPSD, DBPmax, DBPmin, DBPmax−min, and DBPsvmax were significantly associated with HT independent of mean SBP, age, interval from onset to arrival, initial stroke severity, diabetes mellitus, stroke subtype, thrombolysis, initial glucose, and total cholesterol (P<0.05 on likelihood ratio test of trend). The analyses about the interaction between thrombolysis and variability parameters showed that the effects of BP variability on the development of HT did not differ by whether patients received thrombolysis or not. Conclusions— Our study suggests that we may consider not only the absolute level of BP but also its variability to prevent hemorrhagic transformation.

Long-Term Outcomes After Combined Revascularization Surgery in Adult Moyamoya Disease

To determine the clinical characteristics and the effectiveness of encephalo-duro-arterio-synangiosis (EDAS) in adulthood-onset Moyamoya disease (MMD), the authors retrospectively reviewed 26 patients suffering from MMD who were admitted to Seoul National University Hospital between 1987 and 1995. When they showed major symptoms, all were more than 16 years-old. The most common presenting symptom was intracranial hemorrhage (ICrH), found in 12 patients or 46% of the total; the second was infarction and transient ischemic attack, each found in seven or 27% of them. Only one patient was found to have seizures, which were associated with a cerebral infarction. The Suzuki angiographic stage 3 and less than stage 3 accounted for 73% of all 52 hemispheres. A total of 15 patients underwent single photon emission computed tomography (SPECT) preoperatively. When the derangement of cerebral perfusion was estimated with four SPECT grades (SG), 70% of their hemispheres revealed normal (SG1) or localized decreased-perfusion (SG2). The other 30% had extensive decreased-perfusion or localized perfusion defects (SG3). There was no case who had extensive perfusion defects (SG4). A total of 17 patients underwent EDAS operations (EDAS group) and nine did not undergo any operation (no-op group). The EDAS group had significantly better clinical outcomes than the no-op group after a 12-month median follow-up period (P < 0.05). The angiographic and SPECT follow-up studies comprised six and seven cases, respectively. There was also satisfactory angiographic revascularization in all follow-up cases and improvement in cerebral perfusion at SPECT follow-up in six of seven cases. It is concluded that the involvement of posterior circulation of MMD is not frequent and cerebral perfusion is preserved in adulthood-onset MMD patients. These findings may explain the reason why hemorrhages are frequent and the late onset of symptoms in adulthood-onset MMD. Surgical treatment with EDAS seems to be effective in adulthood-onset MMD in terms of clinical improvement.

Is asymptomatic hemorrhagic transformation really innocuous

Background and Purpose— The surgical outcomes of adult moyamoya disease are rarely reported. We aimed to evaluate the long-term outcomes of combined revascularization surgery in patients with adult moyamoya disease. Methods— Combined revascularization surgery consisting of superficial temporal artery–middle cerebral artery anastomosis with encephalodurogaleosynangiosis was performed on 77 hemispheres in 60 patients. Clinical, angiographic, and hemodynamic states were evaluated retrospectively using quantitative methods preoperatively and postoperatively in the short-term (≈6 months) and long-term (≈5 years) periods. The mean clinical follow-up duration was 71.0±10.1 months (range, 60–104 months). Results— Clinical status improved until 6 months after surgery and remained stable thereafter, as assessed by the Karnofsky Performance Scale and modified Rankin Scale. The revascularization area relative to supratentorial area significantly increased in the long-term period compared with that in the short-term period (54.8% versus 44.2%; P<0.001). Cerebral blood flow in the territory of the middle cerebral artery improved in the short-term period compared with that in the preoperative period (68.7 versus 59.1; considering blood flow of the pons as 50; P<0.001) and thereafter became stable (65.5 in the long term; P=0.219). The annual risks of symptomatic hemorrhage and infarction were 0.4% and 0.2%, respectively, in the operated hemispheres. Conclusions— Combined revascularization surgery resulted in satisfactory long-term improvement in clinical, angiographic, and hemodynamic states and prevention of recurrent stroke.