Correlation of Adventitial Vasa Vasorum with Intracranial Atherosclerosis: A Postmortem Study / 대한뇌졸중학회지

BACKGROUND AND PURPOSE: Vasa vasorum (VV) have been believed to be rare or non-existent in small-caliber intracranial arteries. In a series of human cerebral artery specimens, we identified and examined the distribution of VV in association with co-existing intracranial atherosclerosis. METHODS: We obtained cerebral artery specimens from 32 consecutive autopsies of subjects aged 45 years or above. We scrutinized middle cerebral artery (MCA), vertebral artery (VA), and basilar artery (BA) for the presence of adventitial VV. We described the distribution of VV, and the characteristics of co-existing atherosclerotic lesions. RESULTS: Among 157 intracranial arteries, adventitial VV were present in 74 of the 157 specimens (47%), involving MCA (n=13, 18%), BA (n=14, 19%), and VA (n=47, 64%). Although qualitatively these 74 adventitial VV distributed similarly in arteries with or without atherosclerotic lesions (disease-free arteries n=4/8; arteries of pre-atherosclerosis n=17/42; and arteries of progressive atherosclerosis n=53/107), the presence of adventitial VV in intracranial VA was associated with a heavier plaque load (1.72±1.66 mm2 vs. 0.40±0.32 mm2, P < 0.001), severer luminal stenosis (25%±21% vs. 12%±9%, P=0.002), higher rate of concentric lesions (79% vs. 36%, P=0.002), and denser intraplaque calcification (44% vs. 0%, P=0.003). Histologically, intracranial VA with VV had a larger diameter (3.40±0.79 mm vs. 2.34±0.58 mm, P < 0.001), thicker arterial wall (0.31±0.13 mm vs. 0.23±0.06 mm, P=0.002), and a larger intima-media (0.19±0.09 mm vs. 0.13± 0.04 mm, P=0.003) than VA without VV. CONCLUSIONS: Our study demonstrated the distribution of adventitial VV within brain vasculature and association between vertebral VV and progressive atherosclerotic lesions with a heavier plaque load and denser intraplaque calcification.

Intracranial Atherosclerosis: From Microscopy to High-Resolution Magnetic Resonance Imaging / 대한뇌졸중학회지

Intracranial atherosclerosis is one of the leading causes of ischemic stroke and occurs more commonly in patients of Asian, African or Hispanic origin than in Caucasians. Although the histopathology of intracranial atherosclerotic disease resembles extracranial atherosclerosis, there are some notable differences in the onset and severity of atherosclerosis. Current understanding of intracranial atherosclerotic disease has been advanced by the high-resolution magnetic resonance imaging (HRMRI), a novel emerging imaging technique that can directly visualize the vessel wall pathology. However, the pathological validation of HRMRI signal characteristics remains a key step to depict the plaque components and vulnerability in intracranial atherosclerotic lesions. The purpose of this review is to describe the histological features of intracranial atherosclerosis and to state current evidences regarding the validation of MR vessel wall imaging with histopathology.

Association studies of genetic polymorphism and environmental factors in ischemic stroke with atherosclerotic middle cerebral artery stenosis

Objectives: Intracranial atherosclerosis, especially the middle cerebral artery (MCA), is the commonestvascular lesion for ischemic stroke the Chinese population. We explored the association of geneticpolymorphism and environmental factors in MCA atherosclerosis in the Chinese population. Methods:One hundred fifty-six ischemic stroke patients with MCA stenosis and 181 well-matched ischemicstroke patients without MCA stenosis were examined by polymerase chain reaction (PCR). ThePCR products were analyzed for lipoprotein lipase (LPL) S447X and paraoxonase1 (PON1) Q192Rpolymorphisms by restriction enzyme digestion. Medical history documentation and investigationof biochemical markers were performed for each subject. Results: Univariate analysis showed thatthe levels of systolic blood pressure (SBP) were higher in the MCA stenosis group. There were nosignificant differences in the genotype and allele frequencies of the LPL S447X and PON1 Q192Rpolymorphism observed between the two groups. But, in the patients above 60 years of age with andwithout MCA stenosis, LPL X carriers have higher level of SBP than the LPL SS genotype carriers.Multivariate logistic regression found that SBP was the significant, independent predictor of thepresence of MCA stenosis patients above 60 years of age (P < 0.001, OR=1.206, 95% confidenceintervals: 1.014-1.032).Conclusions: SBP appears to contribute to the pathogenesis of MCA stenosis among Chinese. Thegene polymorphism of LPL S447X may be associated with atherosclerotic MCA stenosis in Chinesepopulation.

External Counterpulsation Reduces Beat-to-Beat Blood Pressure Variability When Augmenting Blood Pressure and Cerebral Blood Flow in Ischemic Stroke

BACKGROUND AND PURPOSE: External counterpulsation (ECP) is a noninvasive method used to enhance cerebral perfusion by elevating the blood pressure in ischemic stroke. However, the response of the beat-to-beat blood pressure variability (BPV) in ischemic stroke patients during ECP remains unknown. METHODS: We enrolled recent ischemic stroke patients and healthy controls. Changes in the blood flow velocities in bilateral middle cerebral arteries and the continuous beat-to-beat blood pressure before, during, and after ECP were monitored. Power spectral analysis revealed that the BPV included oscillations at very low frequency (VLF; <0.04 Hz), low frequency (LF; 0.04-0.15 Hz), and high frequency (HF; 0.15-0.40 Hz), and the total power spectral density (TP; <0.40 Hz) and LF/HF ratio were calculated. RESULTS: We found that ECP significantly increased the systolic and diastolic blood pressures in both stroke patients and controls. ECP decreased markedly the systolic and diastolic BPVs at VLF and LF and the TP, and the diastolic BPV at HF when compared with baseline. The decreases in diastolic and systolic BPV reached 37.56% and 23.20%, respectively, at VLF, 21.15% and 12.19% at LF, 8.76% and 16.59% at HF, and 31.92% and 23.62% for the total TP in stroke patients, which did not differ from those in healthy controls. The change in flow velocity on the contralateral side was positively correlated with the total TP systolic BPV change induced by ECP (r=0.312, p=0.035). CONCLUSIONS: ECP reduces the beat-to-beat BPV when increasing the blood pressure and cerebral blood flow velocity in ischemic stroke patients. ECP might be able to improve the clinical outcome by decreasing the beat-to-beat BPV in stroke patients, and this should be explored further in future studies.

Intracranial Artery Calcification and Its Clinical Significance

Intracranial arterial calcification (IAC) is an easily identifiable entity on plain head computed tomography scans. Recent studies have found high prevalence rates for IAC worldwide, and this may be associated with ischemic stroke and cognitive decline. Aging, traditional cardiovascular risk factors, and chronic kidney disease have been found to be associated with IAC. The severity of IAC can be assessed using different visual grading scales or various quantitative methods (by measuring volume or intensity). An objective method for assessing IAC using consistent criteria is urgently required to facilitate comparisons between multiple studies involving diverse populations. There is accumulating evidence from clinical studies that IAC could be utilized as an indicator of intracranial atherosclerosis. However, the pathophysiology underlying the potential correlation between IAC and ischemic stroke-through direct arterial stenosis or plaque stability-remains to be determined. More well-designed clinical studies are needed to explore the predictive values of IAC in vascular events and the underlying pathophysiological mechanisms.

Intracranial Artery Calcification and Its Clinical Significance

Intracranial arterial calcification (IAC) is an easily identifiable entity on plain head computed tomography scans. Recent studies have found high prevalence rates for IAC worldwide, and this may be associated with ischemic stroke and cognitive decline. Aging, traditional cardiovascular risk factors, and chronic kidney disease have been found to be associated with IAC. The severity of IAC can be assessed using different visual grading scales or various quantitative methods (by measuring volume or intensity). An objective method for assessing IAC using consistent criteria is urgently required to facilitate comparisons between multiple studies involving diverse populations. There is accumulating evidence from clinical studies that IAC could be utilized as an indicator of intracranial atherosclerosis. However, the pathophysiology underlying the potential correlation between IAC and ischemic stroke-through direct arterial stenosis or plaque stability-remains to be determined. More well-designed clinical studies are needed to explore the predictive values of IAC in vascular events and the underlying pathophysiological mechanisms.

Herbs and Rehabilitation after Stroke Study: A Multi-center, Double-blinded, Randomized Trial in Hong Kong / 대한뇌졸중학회지

No abstract available.

Clinical profile, risk factors and aetiology of young ischaemic stroke patients in Asia: A prospective, multicentre, observational, hospital-based study in eight cities

Background and Objective: There is a lack of international collaborative studies on young adults with ischaemic stroke in Asia. The aim of this study was to investigate risk factors, aetiology and outcome at hospital discharge of these patients across 8 participating countries in Asia. Methods: This was a prospective, observational, multicentre, hospital based cohort study. Consecutive young stroke patients with confirmed cerebral infarction between the ages of 18-49 were recruited from December 2011 to May 2012. Data was collected for patient demography, risk factors, investigations, clinical profile and TOAST classification. Outcome measures were death and independence (modified Rankin score≤ 2) at hospital discharge. Results: Two hundred and eighteen patients with the mean age was 40.8±6.7 years were recruited. There was a larger proportion of male patients with a ratio of 1.9:1. Traditional risk factors observed were hypertension (n=103; 47.3%), dyslipidaemia (n=93; 42.4%), smoking (n=85; 38.8%), diabetes (n=53; 24.3%), alcohol use (n=33; 15.0%), a previous history of stroke and transient ischaemic attacks (6.4%), family history (n=12; 5.5%), migraine (n=6;2.8%), pregnancy related (n=5; 2.3%) and numerous cardiac risk factors (0.9-5.5%). The majority suffered arterial infarction; n=216 (99.4%) while n=2 (0.6%) had venous strokes. The predominant stroke subtypes were large artery atherosclerosis (LAA); 29.8% and small vessel occlusion (SVO); 20.2%. LAA and SVO accounted for 37.5% of all stroke subtypes in the ≤36 year age-group. Cardioembolism (15.1%) and stroke of determined aetiology (14.7%) contributed to the other categories of identified stroke subtypes. Mortality on hospital discharge was 3.1% while 65.1% of patients were independent on discharge. Conclusion: This study demonstrated the substantial presence of premature atherosclerosis and conventional risk factors in young ischaemic stroke patients from 8 Asian cities. Venous infarction from cerebral venous thrombosis was rare in this study. Outcome on hospital discharge was poorer compared to Western studies. Detection of vascular risk factors and primary prevention measures should be initiated during late adolescence or early adulthood in urban Asia.

Diagnosis and epidemiology of large intracranial artery stenosis / 中国医学科学院学报

Extracranial carotid artery occlusive disease is a major cause of ischemic stroke in Caucasians. However, intracranial artery occlusive disease, especially middle cerebral artery (MCA) stenosis is more significant in Asians. The underlying mechanisms of ischemic stroke with intracranial artery occlusive lesions is different from that of extracranial artery it is expected to recognize the pathogenesis and epidemiology of intracranial artery occlusive disease. By digital magnetic resonance angiography (MRA) and transcranial doppler (TCD) instead of traumatic subtract angiography methods for screening diagnosis of intracranial artery stenosis that were developed in recent two decades. In current paper, we summarized the results studied with MRA and TCD in Peking Union Medical College Hospital and Chinese University of Hong Kong with literatures reviews in this field. Two aspects are discussed (1) Methods for diagnosis of intracranial artery stenosis; (2) Epidemiology of intracranial artery stenosis.