| Part I Clinical Significance of Silent Cerebral Infarction1. Silent cerebral infarction in the neurologically nondiseased elderlyPurpose: To investigate the frequency of silent cerebral infarction (SCI) in the neurologically nondiseased elderly subjects. Material and methods: A total of 109 elderly subjects(mean age 73±6.6 years) were collected from neurological and geriatric clinics of Huanshan hospital from September 2001 to December 2002. All were free from neurological deficit or intellegence dysfunction. Frequency and extent of SCI on FLAIR sequence of MRI (1.5T) were rated separately using Fazekas scale in subcortical white matter and periventricular areas. Results: A total of 89 (81.7%) cases had subcortical white matter hyperintensity(SDWMH). 31 cases had mild, 28 cases had moderate, and 30 cases had severe grade lesions. A total of 93 (85.3%) cases had periventricular hyperintensity(PVH). 17 cases had mild, 37 cases had moderate, and 39 cases had severe grade lesions, A total of 99 (90.8%) cases had SDWMH or PVH. 25 cases had mild, 35 cases had moderate, and 39 cases had severe grade lesions .2. The effects of silent cerebral infarction on clinical manifestation and prognosis inpatients with first-ever ischemic strokePurpose: To investigate the frequency of SCI on MRI, associated factors, and the effects on clinical manifestation and prognosis in patients with first-ever ischemic stroke. Design: Retrospective cohort study. Patients and methods: We studied all patients hospitalized with a diagnosis of first acute cerebral infarction from September 1999 to October 2001. A total of 228 consecutive patients who had no previous history of either stroke or obvious dementia before their index stroke were enrolled in this study. All patients were divided into four groups (normal, mild, moderate, and severe group) according to the localization, size, and numbers of SCI on fluid-attenuated inversion recovery (FLAIR) sequence of MRI. Diffusion-weightedMRI (DWI) was used to evaluate the localization, size of new lesions. Results: MRI showed that a total of 197 patients (86.4%) had SCI. 69 cases had mild, 59 cases had moderate, and 69 cases had severe grade lesions among them. Logistic regression analysis showed the factors independently associated with SCI to be age (the average age was 50.5±5.2, 66.3±6.7, 71.0±5.9, 75.9±7.1 years old in normal, mild, moderate, and severe group, respectively.) (P=0.0001), and control of hypertension (P=0.0122). The extent of SCI was strongly associated with the localization of new lesions on DWI (new lesions occurred in deep white matter were 2/31, 12/69, 12/59, 29/69, in normal, mild, moderate, and severe group, respectively.)(P=0.020), but not with the size. Mean follow-up time was 24 months. 11 patients were lost to follow-up at the end of the study. Life table analysis revealed that the recurrent stroke rate was significantly higher in patients with severe SCI than in those with mild or without SCI (the recurrent stroke rates at 1,2, 3 years out of hospital were 3.23%, 7.83%, 7.83% in normal group; 3.23%, 3.23%, 9.33% in mild group; 9.42%, 16.73%, 16.73% in moderate group; and 15.85%, 30.21%, 43.65% in severe group.) (P=0.0001). Cox proportional hazards model showed predictive factors for recurrent stroke rate were SCI (P=0.001), sustained antiplatelet agents (P=0.037), and hypertension control (P=0.045). The extent of SCI was also significantly associated with the survival rate (the survival rate at 1, 2, 3 years out of hospital were 96.77%, 92.17%, 92.17% in normal group; 96.82%, 96.82%, 91.98% in mild group; 91.67%, 91.67%, 83.73% in moderate group; 87.54%, 78.78%, 75.58% in severe group.)( P=0.0068). But Cox proportional hazards model did not find SCI as a predictive factor for survival rate (P=0.084). Conclusions: This study shows that a high frequency of SCI is found in neurologically nondiseased elderly and patients with first-ever ischemic stroke, the independent risk factors for SCI are age and hypertension control. SCI effects...
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