Seasonal differences and circadian variation in stroke occurrence and stroke subtypes

The role of the SIRT1-BMAL1 pathway in regulating oxidative stress in the early development of ischaemic stroke

Oxidative stress is the primary cause of ischaemic stroke and is closely related to circadian rhythm. However, the mechanism by which circadian rhythm regulates oxidative stress in ischaemic stroke remains elusive. The Silent Information Regulator 1 (SIRT1) controls circadian rhythm by activating the transcription of the circadian clock core protein Basic Helix-Loop-Helix ARNT Like 1 (BMAL1) through deacetylation. Studies have shown that the SIRT1-BMAL1 pathway can regulate oxidative stress. To investigate its correlation with oxidative stress, we examined the expression levels and influencing factors of SIRT1-BMAL1 at different times in ischaemic stroke patients and analyzed their clinical indexes, oxidative stress, and inflammatory factor indicators. The expression levels of oxidative stress and inflammatory factor indicators, including malondialdehyde (MDA), superoxide dismutase (SOD), interleukin-6 (IL-6), and tumor necrosis factor-a (TNF-α), SIRT1, and BMAL1, were detected in ischaemic stroke patients within 4.5 h of onset and in non-stroke patients. Patients were divided into four subgroups based on onset time: subgroup 1 (0:00-05:59); subgroup 2 (06:00-11:59); subgroup 3 (12:00-17: 59); and subgroup 4 (18:00-23:59). Our results showed higher MDA, IL-6, and TNF-α levels, and lower SOD, SIRT1, and BMAL1 levels in ischaemic stroke patients compared to control patients (P < 0.05). Among the four subgroups, the content of MDA, IL-6, and TNF-α was highest in patients with ischaemic stroke onset from subgroup 2 (06:00-11:59), while the expression levels of SOD, BMAL1, and SIRT1 were lowest in patients with ischaemic stroke in subgroup 2. Additionally, myeloperoxidase (MPO) reached the highest value showing the same trends consistent with MDA, IL-6, and TNF-ɑ and opposite trends consistent with SOD, BMAL1, and SIRT1. However, triglycerides (TGs), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), immediate blood glucose, immediate diastolic blood pressure, immediate systolic blood pressure, and homocysteine (HCY) did not show any statistically significant circadian rhythm changes (P > 0.05). Our findings suggest that the SIRT1-BMAL1 pathway may be involved in early oxidative stress in ischaemic stroke, which may be related to MPO.

Seasonal variation in the incidence of primary intracerebral hemorrhage: a 16-year nationwide analysis

Introduction

Data on nationwide trends and seasonal variations in the incidence of Intracerebral Hemorrhage (ICH) in the United States (US) are lacking.

Methods

We used the Nationwide Inpatient Sample (2004-2019) and Census Bureau data to calculate the quarterly (Q1:January-March; Q2:April-June; Q3:July-September; Q4:October-December) incidence rates (IR) of adult (≥18 years) ICH hospitalizations, aggregated across Q1-Q4 and Q2-Q3. We report adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI) for differences in the quarterly incidence of ICH, as compared to acute ischemic stroke (AIS), between Q1Q4 and Q2Q3 using a multivariable Poisson regression model. We additionally performed stratified analyses across the four US regions.

Results

Among 822,143 (49.0% female) ICH and 6,266,234 (51.9% female) AIS hospitalizations, the average quarterly crude IR of ICH was consistently higher in Q1Q4 compared to Q2Q3 (5.6 vs. 5.2 per 100,000) (aIRR, CI: 1.09, 1.08-1.11)-this pattern was similar across all four US regions. However, a similar variation pattern was not observed for AIS incidence. The incidence (aIRR, CI) of both ICH (1.01, 1.00-1.02) and AIS (1.03, 1.02-1.03) is rising.

Conclusion

Unlike AIS, ICH incidence is consistently higher in colder quarters, underscoring the need for evaluation and prevention of factors driving seasonal variations in ICH incidence.

A model of traumatic brain injury in rats is influenced by neuroprotection of diurnal variation which improves motor behavior and histopathology in white matter myelin

Traumatic brain injury (TBI) represents a significant public health concern and has been associated with high rates of morbidity and mortality. TBI generates two types of brain damage: primary and secondary. Secondary damage originates a series of pathophysiological processes, which include metabolic crisis, excitotoxicity, and neuroinflammation, which have deleterious consequences for neuronal function. However, neuroprotective mechanisms are also activated. The balance among these tissue responses, and its variations throughout the day determines the fate of the damage tissue. We have demonstrated less behavioral and morphological damage when a rat model of TBI was induced during the light hours of the day. Moreover, here we show that rats subjected to TBI in the dark lost less body weight than those subjected to TBI in the light, despite no change in food intake. Besides, the rats subjected to TBI in the dark had better performance in the beam walking test and presented less histological damage in the corpus callosum and the cingulum bundle, as shown by the Klüver-Barrera staining. Our results suggest that the time of day when the injury occurs is important. Thus, this data should be used to evaluate the pathophysiological processes of TBI events and develop better therapies.

Association of Time-of-Day Physical Activity With Incident Cardiovascular Disease: The UK Biobank Study

INTRODUCTION

Early morning is characterized by an increased risk of cardiovascular events, a sudden rise in blood pressure, impaired endothelial function, and exacerbated hemodynamic changes during physical activity. The study aims to examine whether the time of day of physical activity is associated with incident cardiovascular disease (CVD).

METHODS

We prospectively analyzed 83,053 participants in the UK Biobank with objectively measured physical activity and initially free of CVD. Based on the diurnal patterns of physical activity, participants were categorized into 4 groups: early morning (n = 15,908), late morning (n = 22,371), midday (n = 24,764), and evening (n = 20,010). Incident CVD was defined as the first diagnosis of coronary heart disease or stroke.

RESULTS

During 197.4 million person-years of follow-up, we identified 3454 CVD cases. After adjusting for the overall acceleration average, the hazard ratios and 95% confidence intervals were 0.95 (0.86-1.07) for late morning, 1.15 (1.03-1.27) for midday, and 1.03 (0.92-1.15) for evening, as compared with the early morning group. In the joint analyses, higher levels of physical activity were associated with a lower risk of incident CVD in a similar manner across the early morning, late morning, and evening groups. However, the beneficial association was attenuated in the midday group.

CONCLUSION

In conclusion, early morning, late morning, and evening are all favorable times of day to engage in physical activity for the primary prevention of CVD, while midday physical activity is associated with an increased risk of CVD compared with early morning physical activity after controlling for the levels of physical activity.

Seasonal Variation in Neurologic Hospitalizations in the United States

OBJECTIVE

Certain neurologic diseases have been noted to vary by season, and this is important for understanding disease mechanisms and risk factors, but seasonality has not been systematically examined across the spectrum of neurologic disease, and methodologic guidance is also lacking.

METHODS

Using nationally representative data from the National Inpatient Sample, a stratified 20% sample of all non-federal acute care hospitalizations in the United States, we calculated the monthly rate of hospitalization for 14 neurologic diseases from 2016 to 2018. For each disease, we assessed seasonality of hospitalization using chi-squared, Edward, and Walter-Elwood tests and seasonal time series regression models. Statistical tests were adjusted for multiple hypothesis testing using Bonferroni correction.

RESULTS

Meningitis, encephalitis, ischemic stroke, intracerebral hemorrhage, Guillain-Barre syndrome, and multiple sclerosis had statistically significant seasonality according to multiple methods of testing. Subarachnoid hemorrhage, status epilepticus, myasthenia gravis, and epilepsy had significant seasonality according to Edwards and Walter-Elwood tests but not chi-square tests. Seasonal time series regression illustrated seasonal variation in all 14 diseases of interest, but statistical testing for seasonality within these models using the Kruskal-Wallis test only achieved statistical significance for meningitis.

INTERPRETATION

Seasonal variation is present across the spectrum of acute neurologic disease, including some conditions for which seasonality has not previously been described, and can be examined using multiple different methods. ANN NEUROL 2023;93:743-751.

Exposure to air pollution and its effect on ischemic strokes (EP-PARTICLES study)

It is well known that exceeded levels of particulate matter in the air and other air pollutants harmfully affect the cardiovascular system. Empirical analyses of the effects of these factors on stroke incidence and mortality are still limited. The main objective of our analyses was to determine the association between short-term exposure to air pollutants and stroke incidence in non-industrial areas, more specifically in north-eastern Poland. To achieve this aim, we used data from the National Health Fund on patients hospitalized for stroke between 2011 and 2020 in the largest city of the region described as the Green Lungs of Poland. The pollution levels and atmospheric conditions data were obtained from the Provincial Inspectorate for Environmental Protection and the Institute of Meteorology and Water Management. Using daily data on hospitalizations, atmospheric conditions, and pollution, as well as ordered logistic regression models the hypotheses on the impact of weather and air pollution conditions on ischemic strokes were tested. The study group included 4838 patients, 45.6% of whom were male; the average patient age was approximately 74 years. The average concentrations of PM_2.5 were 19.09 µg/m³, PM₁₀ 26.66 µg/m³ and CO 0.35 µg/m³. Analyses showed that an increase in PM_2.5 and PM₁₀ concentrations by 10 µg/m³ was associated with an increase in the incidence of stroke on the day of exposure (OR = 1.075, 95% CI 0.999-1.157, P = 0.053; OR = 1.056, 95% CI 1.004-1.110, P = 0.035) and the effect was even several times greater on the occurrence of a stroke event in general (PM_2.5: OR = 1.120, 95% CI 1.013-1.237, P = 0.026; PM₁₀: OR = 1.103, 95% CI 1.028-1.182, P = 0.006). Furthermore, a short-term (up to 3 days) effect of CO on stroke incidence was observed in the study area. An increase of 1 μg/m³ CO was associated with a lower incidence of stroke 2 days after the exposure (OR = 0.976, 95% CI 0.953-0.998, P = 0.037) and a higher incidence 3 days after the exposure (OR = 1.026, 95% CI 1.004-1.049, P = 0.022).

Temporal fluctuations of post-tonsillectomy haemorrhage

Purpose

Although haemorrhage is a common and in some cases life-threatening complication after tonsillectomy, surprisingly little is known about the temporal fluctuations of the onset of bleeding. The purpose of this study was to assess circadian and seasonal rhythms of post-tonsillectomy haemorrhage (PTH) and potential ramifications to educate patients and health care staff.

Methods

This retrospective study carried out at a tertiary referral hospital included paediatric and adult patients requiring emergency surgery due to severe PTH between 1993 and 2019. Medical records were reviewed and patient demographics, details regarding the initial procedure, postoperative day of haemorrhage, and start time of emergency surgery were extracted. Descriptive statistics, Kruskal–Wallis test, Mann–Whitney U test, and Chi-square goodness of fit tests were used to detect potential differences.

Results

A total of 300 patients with severe PTH and subsequent emergency surgery were identified. The median postoperative duration until PTH was 6 (range: < 1–19) days. 64.7% (n = 194) of all emergency surgeries had to be performed during evening and night hours (6 pm—6 am) (p < 0.0001). Compared to diurnal incidents, the risk of a nocturnal PTH event increased, the longer ago the initial surgery was (p < 0.0001). No seasonal variations were identified. Age, sex, and details of the initial procedure had no significant influence on the start time according to the surgical protocol.

Conclusion

The discovered temporal fluctuations of PTH are of relevance for patient awareness and preoperative education. Due to possible life-threatening complications, management of severe PTH requires specific resources and trained medical staff on call.

Seasonal patterns and associations in the incidence of acute ischemic stroke requiring mechanical thrombectomy

Background

In order to identify risk periods with an increased demand in technical and human resources, we tried to determine patterns and associations in the incidence of acute ischemic stroke due to embolic large vessel occlusions (eLVO) requiring mechanical thrombectomy (MT).

Methods

We conducted a time series analysis over a 9‐year period (2010–2018) based on observational data in order to detect seasonal patterns in the incidence of MT due to eLVO (n = 2628 patients). In a series of sequential negative binominal regression models, we aimed to detect further associations (e.g., temperature, atmospheric pressure, air pollution).

Results

There was a 6‐month seasonal pattern in the incidence of MT due to eLVO (p = 0.024) peaking in March and September. Colder overall temperature was associated with an increase in MT due to eLVO (average marginal effect [AME], [95% CI]: −0.15 [−0.30–0.0001]; p = 0.05; per °C). A current increase in the average monthly temperature was associated with a higher incidence of MT due to eLVO (0.34 [0.11–0.56]; p = 0.003). Atmospheric pressure was positively correlated with MT due to eLVO (0.38 [0.13–0.64]; p = 0.003; per hectopascal [hPa]). We could detect no causal correlation between air pollutants and MT due to eLVO.

Conclusions

Our data suggest a 6‐month seasonal pattern in the incidence of MT due to eLVO peaking in spring and early autumn. This might be attributed to two different factors: (1) a current temperature rise (comparing the average monthly temperature in consecutive months) and (2) colder overall temperature. These results could help to identify risk periods requiring an adaptation in local infrastructure.

Diurnal Variation Induces Neurobehavioral and Neuropathological Differences in a Rat Model of Traumatic Brain Injury

Traumatic brain injury (TBI) induces two types of brain damage: primary and secondary. Damage initiates a series of pathophysiological processes, such as metabolic crisis, excitotoxicity with oxidative stress-induced damage, and neuroinflammation. The long-term perpetuation of these processes has deleterious consequences for neuronal function. However, it remains to be elucidated further whether physiological variation in the brain microenvironment, depending on diurnal variations, influences the damage, and consequently, exerts a neuroprotective effect. Here, we established an experimental rat model of TBI and evaluated the effects of TBI induced at two different time points of the light–dark cycle. Behavioral responses were assessed using a 21-point neurobehavioral scale and the cylinder test. Morphological damage was assessed in different regions of the central nervous system. We found that rats that experienced a TBI during the dark hours had better behavioral performance than those injured during the light hours. Differences in behavioral performance correlated with less morphological damage in the perilesional zone. Moreover, certain brain areas (CA1 and dentate gyrus subregions of the hippocampus) were less prone to damage in rats that experienced a TBI during the dark hours. Our results suggest that diurnal variation is a crucial determinant of TBI outcome, and the hour of the day at which an injury occurs should be considered for future research.

Seasonality of stroke: Winter admissions and mortality excess: A Thailand National Stroke population database study

OBJECTIVES

We examined the existence and potential burden of seasonality of stroke admissions and mortality within a tropical climate using cohort data collected between 1 st November 2003 and 31 st October 2012.

PATIENTS AND METHODS

In a prospective cohort of hospitalised stroke patients from the catchment of ∼75 % of the Thai population (n = 569,307; mean SD age = 64(14.5)), incident stroke admissions, in-hospital mortality, prolonged hospitalisations, and stroke related complications by season were determined. Rates of incident stroke admissions by month and season were plotted. Winter excess indexes for study outcomes expressed as a percentage were calculated. Using logistic regression we examined the association between winter admission and in-hospital mortality (non-winter admission as reference) adjusting for age, sex, stroke type, year of admission, and presence of pre-existing comorbidities.

RESULTS

We observed a winter excess in mortality during hospitalisation (+10.3 %) and prolonged length of stay (+7.3 %). Respective winter excess indexes for dyslipidaemias, arrhythmias, anaemia, and alcohol related disorders in patients that died during hospitalisation were +1.4 %, +6.2 %, +0.2 %, +1.5 %. In these patients, respective winter excess indexes for post-stroke complications of pneumonia and sepsis were +6.7 % and +3.2 %. In fully adjusted analyses, winter admission (compared to non-winter admission) was associated with increased odds of in-hospital mortality (OR (95 % CI) = 1.023 (1.006-1.040)).

CONCLUSIONS

We provide robust evidence for the existence of an excess in winter stroke admissions and subsequent in-hospital deaths within a tropical region.

Does the "Weekend Effect" Extend to Friday Admissions? An Analysis of Ischemic Stroke Hospitalizations in South Carolina

Background: Weekend admission has been found to be associated with higher hospital mortality and longer hospital stay among patients with acute cardiovascular conditions. Whether those admitted on Fridays face similar risk as those admitted on Sundays and Saturdays remain uncertain. Methods: This study used 2012-2013 data from hospital records for nonfatal patients with ischemic stroke in the state of South Carolina. The database contained the records of all hospitalizations in South Carolina except military and federal institutions. Multilevel logistic, negative binomial, and log-linear regression models were performed to explore the temporal pattern by hospital admission on specific day of a week for three outcomes: discharge to hospice care (vs. other alive discharges), length of stay, and total charge, respectively. Each model controlled for the patient age, gender, race/ethnicity, year of hospital admission, season of admission, payer, and Charlson Comorbidity Index. Results: A total of 19,346 nonfatal ischemic stroke hospitalizations were identified. Multilevel logistic regression shows that patients admitted on non-Friday weekdays had a significantly lower odds of being discharged to hospice care as compared with those admitted on Fridays [odds ratio = 0.80, 95% confidence interval (CI) = 0.65-0.99] where there was no significant difference between Friday admissions and weekend admissions. The length of hospital stay for admission on non-Friday weekdays was significantly shorter than that of Friday admissions [incident rate ratio (IRR) = 0.87, 95% CI = 0.84-0.90], whereas longer length of hospital stay was found on weekend admission (IRR = 1.06, 95% CI = 1.02-1.11). Friday admissions were not associated with higher charges as compared with non-Friday weekday admissions. Conclusions: Some hospitalization outcomes admitted on Fridays seemed to have the "weekend effects" too. Further studies are warranted to investigate underlying mechanism for such a difference in outcomes between Friday and other weekdays. Interventions to close the weekend-weekday gap of patient outcomes need to consider the elevated risk on Friday admission.

The influence of circadian variation in ischemic stroke onset on the evolution of cognitive status

Introduction. It is already known and accepted that cerebrovascular disease onset has a temporal variation pattern, the best documented being the circadian variation pattern, with a frequency peak in the morning and a second lower peak during afternoon. The impact of this circadian variation on post-stroke cognitive status has been little studied. Materials and method. The study included a cohort of 63 patients with ischemic stroke, admitted to the Neurology Departments I and II of the Rehabilitation Hospital in Cluj-Napoca between 1 June 2008 and 1 June 2009, who were evaluated for their cognitive status over 2 years, during 5 successive visits. The onset time of ischemic stroke was assigned to one of the six-hour intervals: 00.01-06.00 (night), 06.01-12.00 (morning), 12.01-18.00 (afternoon), and 18.01-24.00 (evening). Statistical analysis was performed using Excel Microsoft, descriptive and ANOVA test. Results and conclusions. The circadian variation pattern of stroke onset is confirming in our study the known incidence pattern of ischemic stroke, with the morning peak. There are differences in the evolution during dynamics of the MMSE score depending on the time of the day when stroke occurs. Patients with stroke onset during the night have seems to have a less favorable cognitive evolution in the second year after ischemic stroke compared to patients with stroke onset during the other intervals of the day.

Temperature and Precipitation Associate With Ischemic Stroke Outcomes in the United States

Background

There is disagreement in the literature about the relationship between strokes and seasonal conditions. We sought to (1) describe seasonal patterns of stroke in the United States, and (2) determine the relationship between weather variables and stroke outcomes.

Methods and Results

We performed a cross‐sectional study using Get With The Guidelines‐Stroke data from 896 hospitals across the continental United States. We examined effects of season, climate region, and climate variables on stroke outcomes. We identified 457 638 patients admitted from 2011 to 2015 with ischemic stroke. There was a higher frequency of admissions in winter (116 862 in winter versus 113 689 in spring, 113 569 in summer, and 113 518 in fall; P<0.0001). Winter was associated with higher odds of in‐hospital mortality (odds ratio [OR] 1.08 relative to spring, confidence interval [CI] 1.04–1.13, P=0.0004) and lower odds of discharge home (OR 0.92, CI 0.91–0.94, P<0.0001) or independent ambulation at discharge (OR 0.96, CI 0.94–0.98, P=0.0006). These differences were attenuated after adjusting for climate region and case mix and became inconsistent after controlling for weather variables. Temperature and precipitation were independently associated with outcome after multivariable analysis, with increases in temperature and precipitation associated with lower odds of mortality (OR 0.95, CI 0.93–0.97, P<0.0001 and OR 0.95, CI 0.90–1.00, P=0.035, respectively).

Conclusions

Admissions for ischemic stroke were more frequent in the winter. Warmer and wetter weather conditions were independently associated with better outcomes. Further studies should aim to identify sensitive populations and inform public health measures aimed at resource allocation, readiness, and adaptive strategies.

Frequency of post-tonsillectomy hemorrhage relative to time of day

OBJECTIVES

Postoperative hemorrhage is a serious complication of tonsillectomy, with secondary bleeding rates affecting up to 0.8% to 3% of patients. Although these bleeds are anecdotally perceived as occurring more frequently at night, the occurrence of hemorrhage relative to the time of day has not been investigated. We measured the frequency of post-tonsillectomy hemorrhage onset relative to the time of day.

METHODS

We reviewed electronic medical records of all patients who experienced postprocedural hemorrhage (International Classification of Disease, Ninth Edition [ICD-9] 998.11, ICD-10 J95.830 at two hospitals within a tertiary academic health system in a 10-year period). Patient demographics, time of bleed onset, emergency room [ED] arrival time, and management (operating room vs. observation) were abstracted. Patients without a recorded bleeding time were excluded. Time of bleed onset was categorized as morning (6:01 am-12 pm), afternoon (12:01 pm-6 pm), evening (6:01 pm-12 am), or overnight (12:01 am-6 am). Chi-square goodness of fit test was used to assess the distribution of hemorrhage timing (P ≤ 0.05).

RESULTS

A total of 7,396 patients underwent tonsillectomy May 2008 through May 2018, among whom 121 (2%) post-tonsillectomy hemorrhage patients were identified. Among the 104 patients with ED arrival times, 29 (28%) arrived in the morning; 15 (14%) arrived in the afternoon; 40 (38%) arrived in the evening; and 20 (19%) arrived overnight (P = 0.003). Sixty patients (mean age 17.1 years, standard deviation 16.6) had a recorded timing of bleed onset. Bleed onset occurred most commonly overnight (24, 40%), followed by evening (21, 35%), afternoon (11, 18%), and morning (4, 7%) (P = 0.0007).

CONCLUSION

In this cohort, post-tonsillectomy hemorrhage occurred most frequently between midnight and 6 am. Our findings confirm anecdotal experience and provide data in setting caregiver expectations.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1823-1827, 2020.

Seasonal variation in the occurrence of ischemic stroke: A meta-analysis

Stroke was demonstrated to correlate with seasonal variation. However, the relevant studies were incongruous. To better understand the rules of seasonal impact on ischemic stroke (IS) patients, we performed this meta-analysis. We systematically searched relevant observational studies in Pubmed, Web of science and Embase from January 1, 1980, to November 1, 2017, in English. Patients included in this study were adults who suffered from IS. Stata version 12.0 software was used to pool useful data and calculate incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). We also performed heterogeneity and sensitivity analyses and evaluated publication bias. Thirty-three observational studies involving 234,196 participants were incorporated into the meta-analysis. Summer and December were regarded as reference, respectively. The IRRs were calculated showing: IRR_Winter 1.05 (95% CI 1.04-1.07), IRR_Autumn 1.03 (95% CI 1.02-1.04), IRR_Spring 1.02 (95% CI 1.01-1.03). No obvious difference existed among 12 months. Stratified analyses on Köppen classification were also conducted. Between-study heterogeneity was discovered; however, predefined stratified analyses and meta-regression could not reduce this heterogeneity. Our meta-analysis has revealed very little seasonal variation in the overall study. Both cold and hot months may be high risky for IS after stratified by Köppen Climate Classification. Thus, a rationale to environmental setting of risky patient management could be provided. More studies with specific assessments are warranted for further comprehensive investigation.

Impact of seasonal variations on the first ischemic events in patients with moyamoya disease

OBJECTIVES

This retrospective study aimed to explore the impact of seasonal variations on the first ischemic events in patients with moyamoya disease (MMD).

PATIENTS AND METHODS

Based on the first-time ischemic event occurrence, 113 patients, including 84 with cerebral infarction and 29 with transient ischemic attack, who were diagnosed with ischemic MMD were divided into four groups: spring (March-May), summer (June-August), autumn (September-November) and winter (December-February). The incidence of cerebral infarction was considered as the primary parameter. The impact of seasonal variations on the occurrence of cerebral infarction was analyzed by Poisson regression model and seasonal analysis.

RESULTS

When summer was set as the reference, patients in summer were more significantly susceptible to develop cerebral infarction as compared with spring (IRR, 0.529, 95%CI, 0.299-0.937, p = 0.03), autumn (IRR, 0.441, 95%CI, 0.240-0.810, p < 0.01) and winter (0.500, 95%CI, 0.279-0.895, p = 0.02). The seasonality of the time series in summer (1.231) was substantially higher than that in the other three seasons (-0.269 in spring, -0.656 in autumn and -0.306 in winter). No discrepancy in either NIHSS or mRS scores at admission was observed among the four seasons.

CONCLUSION

Patients with MMD may be more vulnerable to cerebral infarction in summer compared with the other three seasons, and seasonal onset of cerebral infarction does not seem to be associated with the severity of neurological disability at admission.

Seasonal Variations in Neurological Severity and Outcomes of Ischemic Stroke - 5-Year Single-Center Observational Study

BACKGROUND

Seasonal variations in the severity and outcomes of stroke remain unclarified.Methods and Results:A total of 2,965 acute ischemic stroke patients from a single-center prospective registry were studied. Among the total patients, stroke onset did not vary by season, though it varied with a peak in winter when limited to patients >75 years old (P=0.026), when limited to patients with moderate-to-severe initial neurological deficits (National Institutes of Health Stroke Scale Score ≥10, P=0.014), and when limited to those with cardioembolic stroke (n=1,031, P=0.010). In 1,934 patients with noncardioembolic stroke, stroke onset did not vary by season. After multivariable adjustment, moderate-to-severe neurological deficits were more common in winter (odds ratio 1.37, 95% confidence interval 1.10-1.72) and spring (1.27, 1.01-1.60), and death at 1 year was more common in summer than in fall (1.55, 1.03-2.36); death or dependency (modified Rankin Scale score 3-6) and death or bedridden (score of 5-6) were not differently common among the seasons.

CONCLUSIONS

Overall ischemic stroke showed a fairly even distribution among the 4 seasons. Cardioembolic stroke was more common in winter. Ischemic stroke patients had more moderate-to-severe initial neurological deficits in winter and spring. Poor clinical outcomes at 1 year were generally similar among the seasons. Ischemic stroke is not necessarily a winter-dominant disease.

Seasonal variation of admission severity and outcomes in ischemic stroke - a consecutive hospital-based stroke registry

Different morbidities and mortalities of ischemic stroke may occur among seasons. For detecting the seasonal variations of severity after stroke onset and prognosis, we employed a retrospective analysis on a prospective regional hospital-based stroke registry and included a total of 1039 consecutive patients with onset date from January 2014 to December 2015. Patients were divided into four groups according to the onset seasons. Baseline characteristics, stroke subtypes, admission National Institute of Health Stroke Scale (NIHSS) score and modified Rankin Scale (mRS) score in 90 d were recorded and compared. Ordinal logistic regression was used to evaluate the association of seasons and severity or outcomes. Higher proportion of cardiac embolisms appeared in spring and winter (p < 0.001). The median admission NIHSS score was 5 in spring, 3 in summer, 4 in fall and 4 in winter (p = 0.036). After 90 d from onset, 40.5% of patients in spring suffered poor outcome (mRS 3-6), while 24.6% in summer, 33.9% in fall and 40.1% in winter (p < 0.001). After adjusted for age, sex, stroke subtypes and other covariates, patients in spring and winter had 1.76 times (95%CI 1.14-2.70, p = 0.010) and 1.53 times (95%CI 1.08-2.18, p = 0.017) the risk of suffering higher severity category than patients in summer, respectively. Compared with summer group, risk of worse outcomes at 90 d increased to 2.30 times in spring (95%CI 1.53-3.45, p < 0.001), 1.57 times in fall (95%CI 1.14-2.16, p = 0.006) and 2.09 times in winter (95%CI 1.50-2.91, p < 0.001), respectively. In conclusion, onset seasons were associated with severity and outcomes in ischemic stroke, and patients admitted in spring and winter had more severity and worse outcomes than patients in summer.

Changes in erythrocyte deformability during day and possible role of melatonin

OBJECTIVES

The deformability of erythrocytes is their ability to change shape in order to pass through the capillaries. Th is is necessary for quality of microcirculation and sufficient delivery of oxygen to the tissues. Th e aim of our study was to investigate the possible spontaneous changes in the erythrocyte deformability during day and evaluation of the possible direct effects of melatonin (hormone involved in regulation of biorhythms) on the erythrocyte deformability.

METHODS

Samples of capillary blood were taken from 12 healthy volunteers in the morning (8:00) and early in the evening (16:30). Determination of erythrocyte deformability was done based on the measurement of their filtrability. It was measured immediately aft er the sample collection and 2-hour lasting incubation without or with melatonin (2000 μmol/L).

RESULTS

Erythrocyte deformability was significantly lower in the morning (filtrability index: 0.68±0.01 morning vs. 0.71±0.01 early evening, p<0.05). Th e incubation of blood samples with melatonin did not have impact on deformability.

CONCLUSIONS

We suggest the presence of diurnal changes in erythrocyte deformability with worse values in the morning that may contribute to higher risk of ischemic attacks in the morning hours. Direct in vitro effect of melatonin on deformability was not observed, but possible in vivo effects cannot be excluded.

Effect of night-time temperatures on cause and age-specific mortality in London

Supplemental Digital Content is available in the text.

Background:

High ambient temperatures are associated with an acute increase in mortality risk. Although heat exposure during the night is anecdotally cited as being important, this has not been rigorously demonstrated in the epidemiological literature.

Methods:

We quantified the contribution of nighttime temperatures using time-series quasi-Poisson regression on cause and age-specific daily mortality in London between 1993 and 2015. Daytime and nighttime exposures were characterized by average temperatures between 9 am and 9 pm and between 4 am and 8 am, respectively, lagged by 7 days. We also examined the differential impacts of hot and cool nights preceded by very hot days. All models were adjusted for air quality, season, and day of the week. Nighttime models were additionally adjusted for daytime exposure.

Results:

Effects from nighttime exposure persisted after adjusting for daytime exposure. This was highest for stroke, RR (relative risk) = 1.65 (95% confidence interval (CI) = 1.27 to 2.14) estimated by comparing mortality risk at the 80th and 99th temperature percentiles. Compared to daytime exposure, nighttime exposure had a higher mortality risk on chronic ischemic and stroke and in the younger age groups. Respiratory mortality was most sensitive to daytime temperatures. Hot days followed by hot nights had a greater mortality risk than hot days followed by cool nights.

Conclusions:

Nighttime exposures make an additional important contribution to heat-related mortality. This impact was highest on warm nights that were preceded by a hot day, which justifies the alert criteria in heat–health warning system that is based on hot days followed by hot nights. The highest mortality risk was from stroke; targeted interventions would benefit patients most susceptible to stroke.

Hypoxia in CNS Pathologies: Emerging Role of miRNA-Based Neurotherapeutics and Yoga Based Alternative Therapies

Cellular respiration is a vital process for the existence of life. Any condition that results in deprivation of oxygen (also termed as hypoxia) may eventually lead to deleterious effects on the functioning of tissues. Brain being the highest consumer of oxygen is prone to increased risk of hypoxia-induced neurological insults. This in turn has been associated with many diseases of central nervous system (CNS) such as stroke, Alzheimer's, encephalopathy etc. Although several studies have investigated the pathophysiological mechanisms underlying ischemic/hypoxic CNS diseases, the knowledge about protective therapeutic strategies to ameliorate the affected neuronal cells is meager. This has augmented the need to improve our understanding of the hypoxic and ischemic events occurring in the brain and identify novel and alternate treatment modalities for such insults. MicroRNA (miRNAs), small non-coding RNA molecules, have recently emerged as potential neuroprotective agents as well as targets, under hypoxic conditions. These 18-22 nucleotide long RNA molecules are profusely present in brain and other organs and function as gene regulators by cleaving and silencing the gene expression. In brain, these are known to be involved in neuronal differentiation and plasticity. Therefore, targeting miRNA expression represents a novel therapeutic approach to intercede against hypoxic and ischemic brain injury. In the first part of this review, we will discuss the neurophysiological changes caused as a result of hypoxia, followed by the contribution of hypoxia in the neurodegenerative diseases. Secondly, we will provide recent updates and insights into the roles of miRNA in the regulation of genes in oxygen and glucose deprived brain in association with circadian rhythms and how these can be targeted as neuroprotective agents for CNS injuries. Finally, we will emphasize on alternate breathing or yogic interventions to overcome the hypoxia associated anomalies that could ultimately lead to improvement in cerebral perfusion.

Relationship between weather conditions and admissions for ischemic stroke and subarachnoid hemorrhage

AIM

To assess impacts of different weather conditions on hospitalizations of patients with ischemic strokes and subarachnoid hemorrhages (SAH) in South Florida.

METHODS

Diagnostic data of patients with spontaneous SAH and strokes were recorded between June 2010 and July 2013. Daily synchronous forecast charts were collected from the National Weather Service and the whole data were matched prospectively. The incidence rate ratio (IRR) was calculated.

RESULTS

Increased incidence rate of ischemic stroke was consistent with the daily lowest and highest air pressure (IRR 1.03, P=0.128 and IRR 0.98, P=0.380, respectively), highest air temperature (IRR 0.99, P=0.375), and presence of hurricanes or storms (IRR 0.65, P=0.054). Increased incidence of SAH cases was consistent with daily lowest and highest air pressure (IRR 0.87, P<0.001 and IRR 1.08, P=0.019, respectively) and highest air temperature (IRR 0.98, P<0.001). Presence of hurricanes and/or tropical storms did not influence the frequency of SAH. We found no relationship between the presence of fronts and the admissions for ischemic stroke or SAH.

CONCLUSION

Higher number of ischemic stroke and SAH cases can be expected with the daily lowest and highest air pressure, highest air temperature. Presence of hurricanes or tropical storms increased the risk of ischemic stroke but not the SAH. These findings can help to develop preventive health plans for cerebrovascular diseases.

Seasonal and Monthly variation in stroke and its subtypes-10 Year Hospital-Based Study

Background and Objectives:

There is no evidence of long-term studies of seasonal variations in stroke in Iran. Hence, the aim of this study was to determine the seasonal and monthly variation of 28-day mortality in Isfahan, Iran.

Methods:

From 2003 to 2013, In a Hospital-based retrospective study which was conducted by Isfahan Cardiovascular Research Center(ICRC), 24186 cases with first-ever stroke were recruited. Multinomial logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI) for seasonal and monthly 28-day mortality for stroke in general and three subtypes of stroke including intracranial hemorrhage (ICH), ischemic (IS) and subarachnoid hemorrhage (SAH).

Results:

In this study, unadjusted and adjusted odds ratios of seasonal 28-day mortality of stroke was highest in the winter and lowest in the summer. Although, differences were not statistically significant. For total and IS stroke, the unadjusted 28-day mortality ratio (UMR) was significant in February (1.19, 95% CI 1.00 -1.42, P= 0.04) as compared to March. Whereas after adjusted, for total stroke, 28-day mortality was significantly lowest in May (0.746, 95% CI 0.575-0.97, p=0.029), June (0.777, 95% CI 0.60-0.99, p=0.49) and July (0.771, 95% CI 0.59-0.99 p=0.049) as compared to March. The AMR between months were not significant in SAH and IS.

Conclusion:

Our findings demonstrate clear obvious monthly variation of 28-day mortality of stroke and its subtypes in Isfahan but no seasonal variations were observed.

Cerebral Venous Sinus Thrombosis May Follow a Seasonal Pattern

BACKGROUND

Several studies have demonstrated seasonal and temporal variations in the incidence of arterial stroke; however, for cerebral venous sinus thrombosis (CVST), such study seems lacking. The main aim of this study was to investigate whether there is any seasonal variation for CVST, and association between CVST occurrence and temperature.

METHODS

This retrospective study was conducted from January 2004 to July 2015 in 2 referral centers for the patients with cerebrovascular disorders. One hundred and sixty-six consecutive patients with a hospital admission or discharge diagnosis of definite CVST were included. The incidence of CVST was compared between high-temperature and low-temperature months.

RESULTS

The mean age of patients was 36.71 ± 12.44 and 130 (78.31%) subjects were female. The highest frequency of CVST was seen in 3 months of July to September (1.69/month per year); and the lowest frequency of CVST was seen from December to April (.83/month per year). Additionally, there was a significant correlation between the mean average of temperature in each month and the frequency of CVST occurrence (r = .60, P = .03). Moreover, we found a cluster of patients, mostly females, in whom CVST occurred in cold months and accompanied visible cerebral infarct with higher occurrence of seizure, focal neurological deficit, and loss of consciousness.

CONCLUSIONS

It seems that the incidence of CVST increases in high-temperature months of the year and dehydration and ensuing consequences may play an important role in such augmentation; however, the visible cerebral infarct is again more observed in low-temperature months.

Evidence of seasonality and effects of psychrometry in dry eye disease

PURPOSE

Current models consider the development of dry eye disease (DED) as a more or less continuous process with only minor daily variations. Clinical evidence, however, does suggest the existence of phase-like recurring dry eye complaints that may be linked to seasonal environmental conditions. In this survey-based study, we examined the influence of seasonality in dry eye pathophysiology.

METHODS

A specific protocol for a telephone interview was created. Then, 738 patients suffering from dry eye and/or Sjögren's syndrome were interviewed and asked about the impact of the four seasons and other weather conditions on their ocular symptoms. Data were statistically analysed. All data were compared in respect to the relation between season, gender, country of origin and the presence of comorbidities.

RESULTS

Overall, 47% of respondents stated that seasonal conditions had a high impact on their DED symptoms, with only 15% reporting that there was no seasonal impact on their symptoms. Wind was the most commonly reported weather condition to impact dry eye symptoms (for 71% of patients), followed by sunshine (60%) and heat (42%). Cold weather was also reported to aggravate dry eye sensation by 34% of patients. The two seasons most commonly associated with dry eye complaints were summer and winter (for 51% and 43% of patients, respectively). Only 8% stated that no weather conditions affected their symptoms.

DISCUSSION

This study confirms the seasonal enhancement of dry eye sensations and symptoms. Environmental characteristics such as cold and heat as well as wind were the most commonly cited triggering factors. Geographical differences do exist between the countries surveyed and the seasonal peak of complaints appears related to temperature and humidity. The main seasons of dry eye complaints in Europe were winter and summer. Such seasonal characteristics in ocular surface disease should be kept in mind when considering diagnosis and treatment as well when investigating the ocular surface.

CONCLUSION

Our study confirmed high prevalence of both seasonal and weather-related enhancement of dry eye sensations and symptoms.

Prefectural difference in spontaneous intracerebral hemorrhage incidence in Japan analyzed with publically accessible diagnosis procedure combination data: possibilities and limitations

OBJECTIVES

Annually reported, publically accessible Diagnosis Procedure Combination (DPC) data from the Japanese government is a part of the total DPC database of the Japanese medical reimbursement system for hospitalization. Although medical issues can be evaluated with these data promptly, the applicability of these data in epidemiological analyses has not been assessed.

METHODS

We performed analyses using only statistical indices reported on the a government website. As a preliminary step, the prefectural consistency of spontaneous intracerebral hemorrhage (sICH) was examined with prefectural mortality over 20 years. Then the prefectural incidence of sICH for four years was calculated, utilizing publically accessible DPC data. To determine its reliability, the consistency was examined, and correlations were analyzed with three prefectural factors expected to have an effect: the elderly rate, mortality due to sICH, and the non-DPC bed rate. In addition, a comparison model between prefectures with this method was developed by analyzing other prefecture-specific factors.

RESULTS

Prefectural mortality due to sICH and prefectural sICH incidence in the DPC database were both consistent over the years. Prefectural sICH incidence had a constant positive correlation with the elderly rate, a partial correlation with mortality due to sICH, but no correlation with the non-DPC bed rate, which is one of the major biases when utilizing the DPC database. In the comparison model, the factors of low income and alcohol consumption showed increased sICH incidence.

CONCLUSIONS

Although careful attention to its limitations is required, publically accessible DPC data will provide insights into epidemiological issues.

Does Place of Residence or Time of Year Affect the Risk of Stroke Hospitalization and Death? A Descriptive Spatial and Temporal Epidemiologic Study

Background

Identifying geographic areas with significantly high risks of stroke is important for informing public health prevention and control efforts. The objective of this study was to investigate geographic and temporal patterns of stroke hospitalization and mortality risks so as to identify areas and seasons with significantly high burden of the disease in Florida. The information obtained will be useful for resource allocation for disease prevention and control.

Methods

Stroke hospitalization and mortality data from 1992 to 2012 were obtained from the Florida Agency for Health Care Administration. Age-adjusted stroke hospitalization and mortality risks for time periods 1992–94, 1995–97, 1998–2000, 2001–03, 2004–06, 2007–09 and 2010–12 were computed at the county spatial scale. Global Moran’s I statistics were computed for each of the time periods to test for evidence of global spatial clustering. Local Moran indicators of spatial association (LISA) were also computed to identify local areas with significantly high risks.

Results

There were approximately 1.5 million stroke hospitalizations and over 196,000 stroke deaths during the study period. Based on global Moran’s I tests, there was evidence of significant (p<0.05) global spatial clustering of stroke mortality risks but no evidence (p>0.05) of significant global clustering of stroke hospitalization risks. However, LISA showed evidence of local spatial clusters of both hospitalization and mortality risks with significantly high risks being observed in the north while the south had significantly low risks of stroke deaths. There were decreasing temporal trends and seasonal patterns of both hospitalization and mortality risks with peaks in the winter.

Conclusions

Although stroke hospitalization and mortality risks have declined in the past two decades, disparities continue to exist across Florida and it is evident from the results of this study that north Florida may, in fact, be part of the stroke belt despite not being in any of the traditional stroke belt states. These findings are useful for guiding public health efforts to reduce/eliminate inequities in stroke outcomes and inform policy decisions. There is need to continually identify populations with significantly high risks of stroke to better guide the targeting of limited resources to the highest risk populations.

Seasonal variation in hemorrhage and focal neurologic deficit due to intracerebral cavernous malformations

The objective was to determine if there was seasonal variation in the month of symptom onset in patients with intracerebral cavernous malformations (ICM). Patients seen at our institution between 1989 and 1999 with ICM identified from a radiologic database were included. Demographic data and symptoms at onset were abstracted. Symptomatic patients in this ICM database were included if the month of symptom onset was known. Comparison of proportions of patients presenting in fall and winter and during flu season were performed with the chi squared test and Fisher's exact test with significance at p<0.05. Of 292 patients identified, 179 patients had symptomatic ICM. Of these, 135 patients with symptomatic ICM were identified for whom the exact month of symptom onset was known. Eighty-seven (64.4%) presented with intracerebral hemorrhage (ICH) or focal neurologic deficit (FND) and 48 (35.6%) due to seizures. When assessing all 135 patients, 75 (55.5%) presented in the fall and winter compared to the spring and summer (p=0.1962). Eighty-three (61.4%) patients presented during flu season (p=0.0074). When assessing only those initially presenting with ICH or FND, 53 (60.9%) patients presented in the fall and winter compared to spring and summer (p=0.041) and 54 (62.8%) presented during flu season (p=0.017). Patients with recurrent ICH more commonly presented in the fall and winter compared to summer and spring and during flu season. Patients with ICM who presented with FND or ICH or had recurrent ICH tended to present in the fall and winter or during flu season.