Wynnie W.M. Lam

Intracranial stenosis in Chinese patients with acute stroke

We studied 100 consecutive acute stroke patients in a Chinese population with transcranial Doppler and CT. Twenty patients had intracerebral hemorrhage and 14 patients did not have adequate temporal windows for transcranial Doppler examination. Among the remaining 66 patients, 22 patients (33%) had intracranial occlusive diseases and 3 (6%) had extracranial carotid stenosis. Our data showed that intracranial occlusive disease is the most commonly found vascular lesion in our acute stroke patients.

Cerebral Microbleeds as a Risk Factor for Subsequent Intracerebral Hemorrhages Among Patients With Acute Ischemic Stroke

Background and Purpose— Cerebral microbleeds (MBs) detected by gradient-echo MRI are considered evidence of advanced microangiopathy with potential for further bleeding. The goal of this study was to determine whether the presence of MBs is a risk factor for subsequent intracerebral hemorrhage among patients with acute ischemic stroke. Methods— We prospectively examined patients hospitalized with acute cerebral infarction with gradient-echo T2*-weighted MRI for the presence of MBs. We recorded demographics, medical history, and stroke severity. Patients were then followed up for the development of stroke, other vascular events, and death. Results— One hundred twenty-one consecutive patients with a mean age of 67.96±10.97 years were recruited. MBs were present in 43 patients (35.5%). During follow-up of 27.15±11.68 months, 16 patients had recurrent stroke. There was no difference between patients with or without MB for the development of ischemic stroke (5 and 6 respectively, P =0.841). However, 4 patients (9.3%) with MBs and 1 patient (1.3%) without an MB had intracerebral hemorrhage during follow-up (P =0.053). Of the 5 patients who developed subsequent intracerebral hemorrhages, 3 were treated with aspirin and 2 with anticoagulation. Two of the intracerebral hemorrhages occurred in the site where asymptomatic MBs were found at baseline. Conclusions— MBs appear to be a risk factor for subsequent intracerebral hemorrhage among patients with ischemic stroke in this small cohort of Chinese stroke patients. A large cohort study is required to confirm this observation.

Use of Transcranial Doppler Ultrasound to Predict Outcome in Patients With Intracranial Large-Artery Occlusive Disease

Background and Purpose Intracranial large-artery occlusive disease is the predominant vascular lesion found in stroke patients of Asian, African, and Hispanic ancestry, making it numerically perhaps the most common vascular cause of stroke in the world. Relatively little is known about the clinical significance of finding such lesions. We investigate whether the presence and the extent of these vascular lesions help predict outcome after stroke. Methods On the basis of transcranial Doppler of the intracranial arteries with supplementary duplex ultrasound of the carotid arteries, we determined the number of occlusive arteries in the craniocervical circulation of consecutive patients who were hospitalized for acute cerebral ischemia. Patients were followed for 6 months for further vascular events (including transient ischemic attack, stroke, and acute coronary syndrome) or death. Results Among 705 consecutive Chinese patients studied, occlusive arteries were found in 345 patients (49%): 258 patients (37%) had intracranial lesions only, 71 (10%) had both extracranial and intracranial lesions, and 16 (2.3%) had extracranial lesions only. Sixty-three (18%) of the 345 patients with occlusive arteries and 35 (9.7%) of the 360 patients without occlusive arteries had further vascular event or death within 6 months. The risk of vascular events or death increased rapidly with rising numbers of occlusive arteries, after adjustment for vascular risk factors and stroke severity (adjusted odds ratio [OR] 1.25 per occlusive artery, 95% CI 1.12 to 1.39). Other independent risk factors included age (OR 1.03 per year of age, 95% CI 1.01 to 1.05) and atrial fibrillation (OR 3.00, 95% CI 1.40 to 6.69). Conclusions In patients with predominantly intracranial large-artery occlusive disease, the presence and the total number of occlusive arteries in the craniocervical circulation predict further vascular events or death within 6 months after stroke. Transcranial Doppler ultrasound is an important investigation for the evaluation of patients with stroke in populations at risk of intracranial atherosclerotic disease.

Mechanisms of acute cerebral infarctions in patients with middle cerebral artery stenosis: a diffusion-weighted imaging and microemboli monitoring study.

Although most therapeutic efforts and experimental stroke models focus on the concept of complete occlusion of the middle cerebral artery as a result of embolism from the carotid artery or cardiac chamber, relatively little is known about the stroke mechanism of intrinsic middle cerebral artery stenosis. Differences in stroke pathophysiology may require different strategies for prevention and treatment. We prospectively studied 30 consecutive acute ischemic stroke patients with middle cerebral artery stenosis detected by transcranial Doppler and magnetic resonance angiography. Patients underwent microembolic signal monitoring by transcranial Doppler and diffusion‐weighted magnetic resonance imaging. Characteristics of acute infarct on diffusion‐weighted magnetic resonance imaging were categorized according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone, or perforating artery territory infarcts). The data of microembolic signals and diffusion‐weighted magnetic resonance imaging were assessed blindly and independently by separate observers. Diffusion‐weighted magnetic resonance imaging showed that 15 patients (50%) had single acute cerebral infarcts and 15 patients had multiple acute cerebral infarcts. Among patients with multiple acute infarcts, unilateral, deep, chainlike border zone infarcts were the most common pattern (11 patients, 73%), and for single infarcts, penetrating artery infarcts were the most common (10 patients, 67%). Microembolic signals were detected in 10 patients (33%). The median number of microembolic signals per 30 minutes was 15 (range, 3–102). Microembolic signals were found in 9 patients with multiple infarcts and in 1 patient with a single infarct (p = 0.002, χ2). The number of microembolic signals predicted the number of acute infarcts on diffusion‐weighted magnetic resonance imaging (linear regression, adjusted R2 =0.475, p < 0.001). Common stroke mechanisms in patients with middle cerebral artery stenosis are the occlusion of a single penetrating artery to produce a small subcortical lacuna‐like infarct and an artery‐to‐artery embolism with impaired clearance of emboli that produces multiple small cerebral infarcts, especially along the border zone region.

Cognitive impairment and functional outcome after stroke associated with small vessel disease

Objectives: Although stroke associated with small vessel disease (SSVD) can induce both motor and cognitive impairment, the latter has received less attention. We aimed to evaluate the frequency of the varying severity levels of cognitive impairment, the determinants of severe cognitive impairment, and the association of cognitive impairment with functional outcome after SSVD. Methods: Consecutive patients admitted to hospital because of SSVD were assessed at 3 months after stroke. We performed a semi-structured clinical interview to screen for cognitive symptoms. Severity of cognitive symptoms was graded according to the Clinical Dementia Rating Scale (CDR). Performance on psychometric tests (Mini-Mental State Examination, Alzheimer’s Disease Assessment Scale (cognition subscale), Mattis Dementia Rating Scale (initiation/perseverence subscale; MDRS I/P)) of patients of different CDR gradings was compared with that of 42 healthy controls. Basic demographic data, vascular risk factors, stroke severity (National Institute of Health Stroke Scale; NIHSS), pre-stroke cognitive decline (Informant Questionnaire on Cognitive Decline in the Elderly; IQCODE), functional outcome (Barthel index; BI), Instrumental Activities Of Daily Living; IADL), and neuroimaging features (site of recent small infarcts, number of silent small infarcts, white matter changes) were also compared among the groups. Regression analyses were performed to find predictors of severe cognitive impairment and poor functional outcome. Results: Among the 75 included patients, 39 (52%) complained of cognitive symptoms. The number of patients in each CDR grading was as follows: 39 (52%) had a CDR of 0, 26 (34.7%) had a CDR of 0.5, 10 (13.3%) had a CDR of ⩾1. Pre-stroke IQCODE and previous stroke predicted CDR⩾1. The NIHSS was associated with more impaired BI. The NIHSS and MDRS I/P contributed most to impaired IADL. Conclusions: Half of the patients with SSVD complained of varying severity of cognitive problems 3 months after stroke. Pre-stroke cognitive decline and previous stroke predict severe cognitive impairment post stroke. Stroke severity and executive dysfunction contribute most to a poor functional outcome.

Neck node metastases from nasopharyngeal carcinoma: MR imaging of patterns of disease.

The purpose was to use MR imaging to document the patterns of nodal involvement in the upper neck in nasopharyngeal carcinoma (NPC).

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.

Asymptomatic microbleeds as a risk factor for aspirin-associated intracerebral hemorrhages

The authors measured the presence and extent of asymptomatic microbleeds on gradient-recalled-echo MRI in 21 aspirin users who developed intracerebral hemorrhage and 21 aspirin users without history of intracerebral hemorrhage. Microbleeds were more frequent (19 vs 7, p < 0.001) and more extensive (mean number of microbleeds 13.3 vs 0.4, p < 0.001) in the intracerebral hemorrhage group than in the control group. Asymptomatic microbleeds may be a risk factor for aspirin-associated intracerebral hemorrhage.

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.

International reproducibility of single breathhold T2* MR for cardiac and liver iron assessment among five thalassemia centers.

To examine the reproducibility of the single breathhold T2* technique from different scanners, after installation of standard methodology in five international centers.