Myung-Hoon Han

Effect of Seasonal and Monthly Variation in Weather and Air Pollution Factors on Stroke Incidence in Seoul, Korea

Background and Purpose— The purpose of the present study was to determine whether seasonal and monthly variations in stroke incidence exist and whether they are related to meteorologic and air pollution parameters under similar weather and environmental conditions in selected areas of Seongdong district, Seoul, South Korea. Methods— From January 1, 2004, to December 31, 2013, 3001 consecutive stroke events were registered in residents of selected areas of Seongdong district, Seoul, South Korea. The authors calculated the stroke attack rate per 100 000 people per month and the relative risk of stroke incidence associated with meteorologic and air pollution parameters. We also analyzed odds ratios with a 95% confidence interval for seasonal and monthly stroke incidence. Results— The incidence of stroke in September was significantly higher (odds ratio, 1.233; 95% confidence interval, 1.042–1.468) compared with January. The seasonal ischemic stroke incidence in summer (odds ratio, 1.183; 95% confidence interval, 1.056–1.345) was significantly higher than in winter, whereas the seasonal incidence of intracerebral hemorrhage relative to winter was not significant. The mean temperature was positively correlated with ischemic stroke (relative risk, 1.006; P=0.003), and nitrogen dioxide (relative risk, 1.262; P=0.001) showed a strong positive correlation with intracerebral hemorrhage incidence among the older age group. Conclusions— We demonstrated distinct patterns of seasonal and monthly variation in the incidence of stroke and its subtypes through consideration of the meteorologic and air pollution parameters. We therefore expect that these findings may enhance our understanding of the relationships between stroke and weather and pollutants.

Predictive factors for recurrence and clinical outcomes in patients with chronic subdural hematoma

OBJECTIVE Chronic subdural hematoma (CSDH) is a common type of intracranial hemorrhage in elderly patients. Many studies have suggested various factors that may be associated with the recurrence of CSDH. However, the results are inconsistent. The purpose of this study was to determine the associations among patient factors, recurrence, and clinical outcomes of CSDH after bur hole surgery performed during an 11-year period at twin hospitals. METHODS Kaplan-Meier analysis was performed to evaluate the risk factors for CSDH recurrence. Univariate and multivariate Cox proportional hazards regression analyses were used to calculate hazard ratios with 95% CIs for CSDH recurrence based on many variables. One-way repeated-measures ANOVA was used to assess the differences in the mean modified Rankin Scale score between categories for each risk factor during each admission and at the last follow-up. RESULTS This study was a retrospective analysis of 756 consecutive patients with CSDH who underwent bur hole surgery at the Hanyang University Medical Center (Seoul and Guri) between January 1, 2004, and December 31, 2014. During the 6-month follow-up, 104 patients (13.8%) with recurrence after surgery for CSDH were identified. Independent risk factors for recurrence were as follows: age > 75 years (HR 1.72, 95% CI 1.03-2.88; p = 0.039), obesity (body mass index ≥ 25.0 kg/m2), and a bilateral operation. CONCLUSIONS This study determined the risk factors for recurrence of CSDH and their effects on outcomes. Further studies are needed to account for these observations and to determine their underlying mechanisms.

Current Opinion on the Role of Neurogenesis in the Therapeutic Strategies for Alzheimer Disease, Parkinson Disease, and Ischemic Stroke; Considering Neuronal Voiding Function

Neurological diseases such as Alzheimer, Parkinson, and ischemic stroke have increased in occurrence and become important health issues throughout the world. There is currently no effective therapeutic strategy for addressing neurological deficits after the development of these major neurological disorders. In recent years, it has become accepted that adult neural stem cells located in the subventricular and subgranular zones have the ability to proliferate and differentiate in order to replace lost or damaged neural cells. There have been many limitations in the clinical application of both endogenous and exogenous neurogenesis for neurological disorders. However, many studies have investigated novel mechanisms in neurogenesis and have shown that these limitations can potentially be overcome with appropriate stimulation and various approaches. We will review concepts related to possible therapeutic strategies focused on the perspective of neurogenesis for the treatment of patients diagnosed with Alzheimer disease, Parkinson disease, and ischemic stroke based on current reports.

Association between hemorrhagic stroke occurrence and meteorological factors and pollutants

BackgroundThe purpose of this study is to determine whether intracerebral hemorrhage and subarachnoid hemorrhage have different incidence patterns based on monthly variations in meteorological and air pollution parameters in the Seongdong district of Seoul, South Korea.MethodsFrom January 1, 2004 to December 31, 2014, 1,477 consecutive hemorrhagic stroke events (>19 years old) were registered among residents of the Seongdong district, Seoul, South Korea. The authors calculated the relative risk of hemorrhagic stroke and its subtype incidence based on meteorological and air pollution factors. We also estimated relative risk with 95 % confidence intervals using a multivariate Poisson regression model to identify potential independent variables among meteorological factors and pollutants associated with either intracerebral hemorrhage or subarachnoid hemorrhage occurrence.ResultsWe observed a negative correlation between intracerebral hemorrhage and mean temperature. In the multivariate Poisson model, particulate matter with an aerodynamic diameter < 10 μm showed positive correlations with intracerebral hemorrhage (relative risk, 1.09; 95 % confidence interval, 1.02 to 1.15; P = 0.012). In contrast, ozone correlated significantly with subarachnoid hemorrhage occurrence (relative risk, 1.32; 95 % confidence interval, 1.10 to 1.58; P = 0.003).ConclusionsOur findings show the relationship between hemorrhagic stroke and meteorological parameters and pollutants under similar weather and environmental conditions in a small area. Among meteorological and pollutant variables, only higher particulate matter concentrations correlated independently with intracerebral hemorrhage occurrence, while only ozone was independently associated with subarachnoid hemorrhage occurrence. These findings suggest the possibility that there are pathogenic associations between hemorrhagic stroke and meteorological factors and pollutants.

Factors that predict risk of cervical instability in rheumatoid arthritis patients.

Study Design. Retrospective data analysis. Objective. To identify factors affecting the atlantodental interval, the Ranawat value, and subaxial translation after rheumatoid arthritis (RA) diagnosis. In addition, factors predictive for cervical spine instability (CSI) development after RA diagnosis were examined. Summary of Background Data. Development of CSI affects the prognosis and mortality of RA patients. Previous studies described that obesity is associated with reduced radiographic joint damage in RA patients. We hypothesized that body mass index (BMI) is also associated with radiographic cervical damage in RA patients. Methods. Cervical radiographs were taken at full flexion, neutral position, and full extension to measure the geometric length of the anterior atlantodental interval, the Ranawat value, and subaxial translation. These values were entered into multivariable linear regression analysis based on potential associated factors. Hazard ratios were calculated to identify independent factors predictive of CSI. Results. Of the patients diagnosed with RA between January 2005 and August 2015, 1611 who underwent at least one cervical radiograph were included. After adjusting for sex, age, BMI category, CSI, rheumatoid factor, and RA medication, multivariate analysis revealed that the risk of atlantoaxial subluxation in the underweight and normal BMI groups was about 1.6-fold (hazard ratio, 1.63; 95% CI, 1.10–2.43; P = 0.015) and 1.7-fold higher, respectively, than that in the obese group, and that the risk of vertical subluxation was about 2.5-fold (hazard ratio, 2.52; 95% CI, 1.32–4.83; P = 0.005) higher in the underweight group than in the obese group. We also found that the rheumatoid factor positivity was a predictive risk factor for CSI development. Conclusion. We identified risk factors predictive for CSI occurrence after RA diagnosis through cervical radiograph assessment. We found that BMI was an independent predictor for development of CSI. Further large-scale prospective studies are required to confirm these findings. Level of Evidence: 3

Factors Predicting Ventricle Volume Increase After Aneurysmal Clipping in Patients with Subarachnoid Hemorrhage

OBJECTIVE Although many studies have evaluated risk factors associated with hydrocephalus after aneurysmal subarachnoid hemorrhage, specific ventricle volume changes after subarachnoid hemorrhage have not been evaluated. We sought to evaluate factors predicting ventricle volume enlargement in patients with aneurysmal subarachnoid hemorrhage by measuring ventricle volume with a validated, semiautomated tool. METHODS Uni- and multivariable linear regression analyses were conducted with the follow-up ventricle volume as the dependent variable and the duration between subarachnoid hemorrhage occurrence and follow-up imaging as the independent variable, classified by the use of various predictive factors. A logistic regression model was used to calculate the odds ratio for the greater ventricle volume group compared with the lower ventricle volume group based on predictive factors. RESULTS We included 173 participants with a mean age of 55.5 years. Overall, an approximate increase in ventricle volume of 1.1 mL was observed daily within 60 days of clipping due to subarachnoid hemorrhage. In the multivariate logistic regression analysis, patients in the first and second tertile groups for body mass index showed approximately a 5.9- and 4.1-fold increased risk of greater follow-up ventricle volume, respectively, compared with the third tertile group for body mass index within 60 days of subarachnoid hemorrhage. CONCLUSIONS We found that greater body mass index independently predicted suppression of ventricle volume growth, owing to maintenance of subarachnoid trabeculae structures after subarachnoid hemorrhage. Further studies are needed to confirm our findings.

Radiologic Findings and Patient Factors Associated with 30-Day Mortality after Surgical Evacuation of Subdural Hematoma in Patients Less Than 65 Years Old

Objective The purpose of this study is to evaluate the associations between 30-day mortality and various radiological and clinical factors in patients with traumatic acute subdural hematoma (SDH). During the 11-year study period, young patients who underwent surgery for SDH were followed for 30 days. Patients who died due to other medical comorbidities or other organ problems were not included in the study population. Methods From January 1, 2004 to December 31, 2014, 318 consecutive surgically-treated traumatic acute SDH patients were registered for the study. The Kaplan–Meier method was used to analyze 30-day survival rates. We also estimated the hazard ratios of various variables in order to identify the independent predictors of 30-day mortality. Results We observed a negative correlation between 30-day mortality and Glasgow coma scale score (per 1-point score increase) (hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.52–0.70; p<0.001). In addition, use of antithrombotics (HR, 2.34; 95% CI, 1.27–4.33; p=0.008), history of diabetes mellitus (HR, 2.28; 95% CI, 1.20–4.32; p=0.015), and accompanying traumatic subarachnoid hemorrhage (hazard ratio, 2.13; 95% CI, 1.27–3.58; p=0.005) were positively associated with 30-day mortality. Conclusion We found significant associations between short-term mortality after surgery for traumatic acute SDH and lower Glasgow Coma Scale scores, use of antithrombotics, history of diabetes mellitus, and accompanying traumatic subarachnoid hemorrhage at admission. We expect these findings to be helpful for selecting patients for surgical treatment of traumatic acute SDH, and for making accurate prognoses.

Association between Diurnal Variation of Ozone Concentration and Stroke Occurrence: 24-Hour Time Series Study.

Background and Purpose Increasing ozone concentrations have been known to damage human health and ecosystems. Although ozone tends to display diurnal variation, most studies have reported only on the association between daily ozone concentrations and ischemic stroke occurrence on the same day, or with a 1-day lag. We investigated the effect of the diurnal variation of ozone on ischemic stroke occurrence during the same day. Methods We included a consecutive series of 1,734 patients from January 1, 2008, to December 31, 2014, at a single tertiary hospital in Seoul, South Korea. We evaluated differences between temperature and pollutants at the time of stroke onset for each time interval and averaged those parameters across the 7-year study period. Results During the interval from 13:00 to 16:59, we found a positive association between ischemic stroke occurrence and ozone concentration relative to other time periods. Upper median ozone levels from 13:00 to 16:59 were positively correlated with ischemic stroke (odds ratio, 1.550; 95% confidence intervals, 1.220 to 1.970; P = <0.001) when compared with lower median levels. Conclusions The results show diurnal patterns of ischemic stroke occurrence based on upper and lower median ozone levels for a 24-hour period, which extends understanding of the association between stroke occurrence and environmental influences.

Association Between Possible Osteoporosis and Shunt-Dependent Hydrocephalus After Subarachnoid Hemorrhage

Background and Purpose— Pathological obstruction in arachnoid granulations after subarachnoid hemorrhage (SAH) can impede cerebrospinal fluid flow outward to the venous sinus and causing hydrocephalus. Because bone and arachnoid granulations share the same collagen type, we evaluated the possible relation between bone mineral density and shunt-dependent hydrocephalus after SAH. Methods— We measured Hounsfield units of the frontal skull on admission brain computed tomography in patients with SAH. Receiver operating characteristic curve analysis was performed to determine the optimal cutoff Hounsfield unit in skull to predict osteopenia and osteoporosis in a large sample registry. According to the optimal cutoff skull Hounsfield unit values, study patients were then categorized as hypothetical normal, osteopenia, and osteoporosis. Odds ratios were estimated using logistic regression to determine whether the osteoporotic conditions are independent predictive factors for the development of shunt-dependent hydrocephalus after clipping for SAH. Results— A total of 447 patients (alive ≥14 days) with ruptured aneurysm SAH who underwent surgical clipping were retrospectively enrolled in this study during a 9-year period from 2 hospitals. We found that hypothetical osteoporosis was an independent predictor for shunt-dependent hydrocephalus after aneurysmal clipping for SAH after full adjustment for other predictive factors, including age (odds ratio, 2.08; 95% confidence interval, 1.06–4.08; P=0.032). Conclusions— Our study demonstrates a possible relation between possible osteoporosis and hydrocephalus after SAH. Hounsfield unit measurement on admission brain computed tomography may be helpful for predicting hydrocephalus during the clinical course of SAH in patients with osteoporosis or suspected osteoporosis.

The frontal skull Hounsfield unit value can predict ventricular enlargement in patients with subarachnoid haemorrhage

Hydrocephalus is a common complication following subarachnoid haemorrhage (SAH) arising from spontaneous aneurysm rupture. The Hounsfield unit (HU) value from computed tomography scans may reflect bone mineral density, which correlates with body mass index, which in turn is related to post-SAH ventricle size changes. We herein investigated potential associations between frontal skull HU values and ventricle size changes after SAH. HU values from four different areas in the frontal bone were averaged to minimize measurement errors. The bicaudate index and Evans ratio were measured using both baseline and follow-up CT images. CT images with bicaudate index >0.2 and Evans ratio >0.3 simultaneously were defined as indicating ventriculomegaly. We included 232 consecutive patients with SAH due to primary spontaneous aneurysm rupture, who underwent clipping over almost a 9-year period at a single institution. The first tertile of frontal skull HU values in older patients (≥55 years) was an independent predictor of ventriculomegaly after SAH, as compared to the third tertile in younger patients (hazard ratio, 4.01; 95% confidence interval 1.21–13.30; p = 0.023). The lower frontal skull HU value independently predicted ventricular enlargement post-SAH, due to the potential weak integrity of subarachnoid trabecular structures in younger patients.