Wake-up Stroke: Clinical Characteristics, Risk Factors, CISS And Outcomes

Background: With the high rate of incidence, mortality and disability, stroke has become one of the main diseases which threaten public health. Currently, intravenous thrombolysis represents the only effective and approved specific treatment for acute ischemic stroke. However, wake-up stroke, an unknown time of onset, usually represents a contraindication to thrombolysis in stroke. As reported by foreign studies, about 8%-38.9% of strokes are estimated to occur during sleep, while there is a lack of epidemiological data, with large sample, in China.Objective: To summarize the wake-up stroke patients in clinical characteristics, risk factors, CISS etiology subtype and pathophysiological mechanisms, and prognosis after treatment, preparing for further clinical research in wake-up stroke patients.Method: Acute ischemic stroke patients, confirmed radiographically by restricted diffusion on brain magnetic resonance imaging, presenting to Chengde Central Hospital from October 2013 to September 2014 were prospectively enrolled. They were divided into non-wake-up stroke and wake-up stroke groups(non-WUS group and WUS group), according to the time of symptom onset. According to Chinese ischemic stroke subclassification(CISS), the patients fell into large artery atherosclerosis(LAA), penetrating artery disease(PAD), cardiogenic stroke(CS), other etiology(OE) and undetermined etiology(UE) groups. And stroke severity was assessed using the National Institutes of Health Stroke Scale(NIHSS). As risk factors, statistics of family history, hypertension, diabetes, hyperlipidemia, atrial fibrillation, heart valve disease, transient ischemic attack(TIA), smoking, and drinking of patients were recorded, as well as high level of homocysteine and other assistant examinations(brain CT, MRI scan, carotid artery ultrasound, TCD, CTA, MRA, and DSA). Individualized treatments were applied to patients, according to different etiology. Follow-up was carried out by specially-assigned person, with outpatient visit, after the onset of 3 months, in order to work out the conditions of the patients, such as mortality, disability, etc. Descriptive statistics included frequency for categorical variables, mean and standard deviation for continuous variables, and medians with interquartile range for ordinal variables. Characteristics of wake-up stroke were compared with non-wake-up stroke using Student t test for categorical, continuous, and ordinal variables, respectively. All significance levels reported were 2 sided. Analyses were conducted using the SPSS 19.0 statistical package.Results:1 The ratio of WUS in Chengde area accounts for 12.01%, with the M/F ratio of 48/13, and the mean age 50.80±10.09 years old. The risk factors in patients: hypertension 46 cases, smoking 35, elevated homocysteine 30, etc.2 According to CISS: LAA 77.05%(47/61), PAD 3.28%(2/61), CE 8.20%(5/61), OE 3.28%(2/61)and UE 8.20%(5/61); as for the mechanism, parent artery(plaque or thrombosis) occluding penetrating artery(23/47)and artery-to-artery embolism(11/47) are the main types. CE makes a higher rate in female(23.08%,3/13).3 The NIHSS score varies from 0 to 21, and 32 cases from WUS group score less than 4, indicating that minor stroke is a main type in WUS; the anterior circulation lesions are found in 35 cases, while posterior ones 23, and both circulation lesions 3, indicating that posterior lesions are common.4 There is a higher incidence of posterior lesions in WUS(P<0.05), the mortality of two groups share similarity, but the patients with WUS has a worsen recovery of neurological functions(P<0.05).Conclusions:1 The ratio of WUS in Chengde is lower than that of Europe and US, and similar to that of Japan, indicating regional or racial features. It attacks more male, younger people, and some of the patients reach good outcomes by magnetic resonance imaging-based thrombolysis.2 The type of LAA in WUS from Chengde area makes the major etiology, and parent artery(plaque or thrombosis) occluding penetrating artery takes the dominant position, which is different from that of foreign study. The classical risk factors are common in WUS.3 The WUS patients suffer from worsen prognosis. And because of the high rate of posterior circulation lesions, magnetic resonance imaging-based thrombolysis may be a potential treatment.