Lawrence K.S. Wong

Global burden of intracranial atherosclerosis

Stroke is a heterogeneous disease with a plethora of differing stroke mechanisms. Small vessel, large artery atherosclerosis and cardio-embolic stroke are the most common subtypes encountered in clinical practice. Different stroke mechanisms may require different treatment. Anticoagulation for atrial fibrillation is a good example. Many recent research and clinical trials successfully targeted individual stroke subtypes rather than indiscriminately grouping all strokes together. For large artery atherosclerosis, carotid stenosis is the most common vascular lesion found in Caucasians in America and Europe and is extensively studied in terms of epidemiology, pathophysiology and treatment. Unfortunately, relatively little is known about intracranial atherosclerosis until recently; now, modern neuroimaging methods permit noninvasive screening of susceptible patients. Intracranial atherosclerosis affects the middle cerebral artery, intracranial portion of the internal carotid artery, vertebrobasilar artery, posterior, and anterior cerebral arteries. Examples of intracranial stenosis are shown in Figs 1 and 2. Transcranial Doppler ultrasound, CT angiography and MR angiography are now routinely available in clinical practice (1–4). Although digital subtraction angiography remains the gold standard of diagnosis of intracranial atherosclerosis, these noninvasive tests have been validated against clinical outcomes and events (5–7). For decades, it is well described that patients of Asian, African, and Hispanic ancestry were at higher risk of intracranial atherosclerosis (8). More recent studies on consecutive patients confirm this finding and pinpoint the frequency of intracranial atherosclerosis. In Chinese populations, intracranial atherosclerosis accounts for about 33–50% of stroke and 450% of TIA (6, 9, 10). In Thailand, intracranial atherosclerosis was found in 47% of stroke patients (11). In Koreans, 56 3% of stroke patients had intracranial atherosclerosis although the authors used 30% stenosis as cutoff (12). In Singapore, significant intracranial stenosis was found in 47 9% of stroke patients (13). In Japan, the frequency of intracranial atherosclerosis remains high despite increasing frequency of extracranial carotid stenosis (14). In North America, extracranial carotid stenosis remains the most common vascular lesion in Caucasian stroke patients. However, when compared with Caucasians, the relative rate of intracranial atherosclerotic stroke was 5 00 for Hispanics and 5 85 for blacks (15). Based on the widespread observation worldwide that intracranial atherosclerosis is the most common vascular lesions in Asians, Hispanics and Africans, and Caucasians remain the only ethic group with a low frequency of intracranial atherosclerosis. As the majority of the world’s populations are Asians, Africans or Hispanic, it is reasonable to conclude that intracranial atherosclerosis is the most common vascular lesion in stroke patients worldwide. Not only the number of patients with intracranial atherosclerosis is staggering but also patients with intracranial disease are at a high risk of recurrence of up to 25–30% in 2 years after stroke (5, 7, 16), further magnifying the burden of intracranial disease. Unfortunately, there has been

Risk vs benefit of anti-thrombotic therapy in ischaemic stroke patients with cerebral microbleeds

BackgroundRetrospective studies suggested that cerebral microbleeds (MB) on magnetic resonance images (MRI) increase risk of intracerebral haemorrhage (ICH).ObjectiveTo compare the benefit of anti-thrombotic agents in stroke prevention (absolute risk reduction 2.49 –6 %) versus risk of ICH in ischaemic stroke patients with MB.Materials and methodsWe prospectively studied patients admitted consecutively for acute ischaemic stroke between 1999 and 2004. MB on MRI were documented. Primary end points were subsequent ICH, recurrent cerebral infarct (CI) and mortality.ResultsA total of 908 patients were recruited. MB were identified in 252 (27.8 %) patients. Mean follow-up period was 26.6 ± 15.4 months. Risk of subsequent ICH increased significantly with quantity of MB: 0.6 % (no MB), 1.9 % (1 MB), 4.6 % (2–4 MB) and 7.6 % (≥ 5 MB) (p < 0.001). There was also a significant increase in mortality from ICH: 0.6 %, 0.9 %, 1.5 % and 3.8 % respectively (p = 0.054). Rate of recurrent CI was 9.6 %, 5.6 %, 21.5 % and 15.2 % respectively (p = 0.226). Mortality from CI and myocardial infarction did not increased with quantity of MB. Survival analyses showed that age, presence of MB, mixed cortical-subcortical distribution of MB were independent predictors of subsequent ICH.ConclusionRisk and mortality of ICH increased with quantity of MB. As tendency to recurrent CI exceed that of ICH, anti-thrombotic agents are still warranted. However, in patients with ≥ 5 MB, the high risk and mortality of ICH seem to outweigh the modest benefit of antithrombotic agents. Extra precautions should be taken to minimize risk of ICH. Further studies in patients on Coumadin and assessment of functional outcome are warranted to support these preliminary findings.

A randomized controlled trial of surgery vs steroid injection for carpal tunnel syndrome

Background: Decompressive surgery and steroid injection are widely used forms of treatment for carpal tunnel syndrome (CTS) but there is no consensus on their effectiveness in comparison to each other. The authors evaluated the efficacy of surgery vs steroid injection in relieving symptoms in patients with CTS. Methods: The authors conducted a randomized, single blind, controlled trial. Fifty patients with electrophysiologically confirmed idiopathic CTS were randomized and assigned to open carpal tunnel release (25 patients) or to a single injection of steroid (25 patients). Patients were followed up at 6 and 20 weeks. The primary outcome was symptom relief in terms of the Global Symptom Score (GSS), which rates symptoms on a scale of 0 (no symptoms) to 50 (most severe). Nerve conduction studies and grip strength measurements were used as secondary outcome assessments. Results: At 20 weeks after randomization, patients who underwent surgery had greater symptomatic improvement than those who were injected. The mean improvement in GSS after 20 weeks was 24.2 (SD 11.0) in the surgery group vs 8.7 (SD 13.0) in the injection group (p < 0.001); surgical decompression also resulted in greater improvement in median nerve distal motor latencies and sensory nerve conduction velocity. Mean grip strength in the surgical group was reduced by 1.7 kg (SD 5.1) compared with a gain of 2.4 kg (SD 5.5) in the injection group. Conclusion: Compared with steroid injection, open carpal tunnel release resulted in better symptomatic and neurophysiologic outcome but not grip strength in patients with idiopathic carpal tunnel syndrome over a 20-week period.

The China National Stroke Registry for patients with acute cerebrovascular events: design, rationale, and baseline patient characteristics

Background As a leading cause of severe disability and death, stroke places an enormous burden on the health care system in China. There are limited data on the pattern of current medical practice and quality of care delivery for stroke patients at the national level. Aim The nation-wide prospective registry, China National Stroke Registry, will be considered with regard to its design, progress, geographic coverage, and hospital and patient characteristics. Methods Between September 2007 and August 2008, the China National Stroke Registry recruited consecutive patients with diagnoses of acute cerebrovascular events from 132 hospitals that cover all 27 provinces and four municipalities (including Hong Kong region) in China. Clinical data were collected prospectively using paper-based registry forms. Patients were followed for clinical and functional outcomes through phone interviews at three, six, 12, 18, and 24 months after disease onset. Results These patients (n = 21 902) were 63·8 years of age on average, and 39% were females. Ischaemic stroke was predominant (66·4%), and the other subtypes were intracerebral haemorrhage (23·4%), subarachnoid haemorrhage (3·4%), and transient ischaemic attack (6·2%). Conclusions The China National Stroke Registry is a large-scale nationwide registry in China. Rich data collected from this prospective registry may provide the opportunity to evaluate the quality of care for stroke patients in China.

The Validity, Reliability and Clinical Utility of the Hong Kong Montreal Cognitive Assessment (HK-MoCA) in Patients with Cerebral Small Vessel Disease

Background/Aims: To evaluate the psychometric properties of the Hong Kong Montreal Cognitive Assessment (HK-MoCA) in patients with cerebral small vessel disease (SVD). Methods: 40 SVD patients and 40 matched controls were recruited. Concurrent and criterion validity, inter-rater and test-retest reliability, internal consistency of the HK-MoCA were examined and clinical observations were made. Results: Performance on the HK-MoCA was significantly predicted by both executive (β = 0.23, p = 0.013) and non-executive (β = 0.64, p < 0.001) composite scores. It differentiated SVD patients from controls (area under the curve = 0.81, p < 0.001) with an optimal cutoff at 21/22. Reliability, internal consistency and clinical utility were good. Conclusion: The HK-MoCA is a useful cognitive screening instrument for use in SVD patients.

Grading Carotid Stenosis Using Ultrasonic Methods

The controversy as to whether Doppler ultrasonic methods should play a role in clinical decision-making in the prevention of stroke is attributable to reported disagreement between angiographic and ultrasonic results and the lack of internationally accepted ultrasound criteria for describing the degree of stenosis. Foremost among the explanations for both is the broad scatter of peak systolic velocities in the stenosis, the criterion that has so far received most attention. Grading based on a set of main and additional criteria can overcome diagnostic errors. Morphological measurements (B-mode images and color flow imaging) are the main criteria for low and moderate degrees of stenosis. Increased velocities in the stenosis indicate narrowing, but the appearance of collateral flow and decreased poststenotic flow velocity prove a high degree stenosis (≥70%), additionally allowing the estimation of the hemodynamic effect in the category of high-degree stenosis. Additional criteria refer to the effect of a stenosis on prestenotic flow (common carotid artery), the extent of poststenotic flow disturbances, and derived velocity criteria (diastolic peak velocity and the carotid ratio). This multiparametric approach is intended to increase the reliability and the standard of reporting of ultrasonic results for arteriosclerotic disease of the carotid artery.

One-Year Risk of Stroke after Transient Ischemic Attack or Minor Stroke

BACKGROUND Previous studies conducted between 1997 and 2003 estimated that the risk of stroke or an acute coronary syndrome was 12 to 20% during the first 3 months after a transient ischemic attack (TIA) or minor stroke. The TIAregistry.org project was designed to describe the contemporary profile, etiologic factors, and outcomes in patients with a TIA or minor ischemic stroke who receive care in health systems that now offer urgent evaluation by stroke specialists. METHODS We recruited patients who had had a TIA or minor stroke within the previous 7 days. Sites were selected if they had systems dedicated to urgent evaluation of patients with TIA. We estimated the 1-year risk of stroke and of the composite outcome of stroke, an acute coronary syndrome, or death from cardiovascular causes. We also examined the association of the ABCD(2) score for the risk of stroke (range, 0 [lowest risk] to 7 [highest risk]), findings on brain imaging, and cause of TIA or minor stroke with the risk of recurrent stroke over a period of 1 year. RESULTS From 2009 through 2011, we enrolled 4789 patients at 61 sites in 21 countries. A total of 78.4% of the patients were evaluated by stroke specialists within 24 hours after symptom onset. A total of 33.4% of the patients had an acute brain infarction, 23.2% had at least one extracranial or intracranial stenosis of 50% or more, and 10.4% had atrial fibrillation. The Kaplan-Meier estimate of the 1-year event rate of the composite cardiovascular outcome was 6.2% (95% confidence interval, 5.5 to 7.0). Kaplan-Meier estimates of the stroke rate at days 2, 7, 30, 90, and 365 were 1.5%, 2.1%, 2.8%, 3.7%, and 5.1%, respectively. In multivariable analyses, multiple infarctions on brain imaging, large-artery atherosclerosis, and an ABCD(2) score of 6 or 7 were each associated with more than a doubling of the risk of stroke. CONCLUSIONS We observed a lower risk of cardiovascular events after TIA than previously reported. The ABCD(2) score, findings on brain imaging, and status with respect to large-artery atherosclerosis helped stratify the risk of recurrent stroke within 1 year after a TIA or minor stroke. (Funded by Sanofi and Bristol-Myers Squibb.).

Bacterial meningitis in Hong Kong: 10-years’ experience

OBJECTIVE We studied the etiology, clinical features and outcome of patients with bacterial meningitis from an urban Chinese city over a 10-years period. METHODS We reviewed the files of all persons aged 15-years old or above diagnosed with community-acquired bacterial meningitis from a regional hospital. The clinical findings, relevant laboratory and imaging results as well as outcome were recorded in cases with microbiological evidence of meningitis. Neurosurgical and pediatric patients were excluded. RESULTS Sixty-five patients between the ages of 15 and 86 years of age (mean 52 years) were identified of whom 18 (28%) died. The four most common causes were Mycobacteria tuberculosis (46%), Streptococcus pneumoniae (11%), Streptococcus suis (9%) and Klebsiella pneumoniae (8%). Neisseria meningitidis and Haemophilus influenzae were rare pathogens. The annual incidence of community-acquired bacterial meningitis was 1.27/100,000 adults. Delay in treatment was associated with a poorer prognosis (p<0.001, OR=38.84, CI=7.33-205.80). CONCLUSION The causative organisms found in this region of China differ from that reported from Europe and the US; tuberculous meningitis is the most common cause of bacterial meningitis.

Risk factors for incident dementia after stroke and transient ischemic attack

We hypothesized that chronic brain changes are important substrates for incident dementia after stroke and transient ischemic attack (TIA).

Comparison of Recovery Patterns and Prognostic Indicators for Ischemic and Hemorrhagic Stroke in China The ChinaQUEST (QUality Evaluation of Stroke Care and Treatment) Registry Study

Background and Purpose— Limited data exist on the comparative recovery patterns and outcomes of patients with ischemic stroke and intracerebral hemorrhage in China. Methods— Data on baseline characteristics and outcomes of 6354 patients at 3 and 12 months poststroke are from ChinaQUEST (QUality Evaluation of Stroke Care and Treatment), a multicenter, prospective, 62-hospital registry study in China. Logistic regression was used to determine factors associated with a poor outcome defined by death/dependency (modified Rankin Scale score of 3 to 5) on follow-up. Generalized estimating equations were used to assess variations in recovery pattern by stroke type. Results— Baseline severity and rate of functional recovery in the early phase were significantly greater for intracerebral hemorrhage. However, patients with ischemic stroke were on average twice as likely to experience a good outcome (modified Rankin Scale score <3) by 12 months poststroke (OR: 1.98, CI: 1.76 to 2.24). In patients with ischemic stroke, diabetes and atrial fibrillation were strongly associated with a poor outcome at 12 months poststroke even after adjustment for confounding factors such as age, prior stroke/dependency, time to presentation, and stroke severity, whereas use of antiplatelets and lipid-lowering therapy after stroke were associated with improved outcome. For patients with intracerebral hemorrhage, low education and atrial fibrillation were associated with a poor outcome after adjustment for potential confounders and antihypertensive use was strongly associated with improved outcome. Conclusions— Patients with intracerebral hemorrhage and ischemic stroke have different recovery patterns in China. However, they share similar prognostic factors and in the use of evidence-based secondary prevention therapies to maximize chances of a good outcome.