Genetic polymorphisms of low density lipoprotein receptor can modify stroke presentation.

Low density lipoprotein is transcytosed across the blood-brain barrier mediated by low density lipoprotein receptor (LDLR). LDLR in the brain is mainly expressed on capillary endothelial cells and is therefore considered to be an important susceptibility gene in modifying the stroke presentation. A HapMap-based haplotype-tagging single nucleotide polymorphism association study was conducted in an isolated Taiwanese population. Two hundred and ninety-two unrelated patients with cerebral infarction, 76 patients with small vessel occlusion (SVO) disorder and 216 with non-SVO disorder were enrolled. For rs2738446, under the dominant model, the odds ratios (ORs) associated with the CC genotype were computed, with GG + CG carriers considered as the reference group. Homozygote CC carriers had a two-fold increased risk of SVO disorder [OR=2.0, 95% confidence interval (CI)=1.08-3.70, p=0.025). For rs2738450, under the dominant model, the ORs associated with the CC genotype were computed, with AA + AC carriers considered as the reference group. Homozygote CC carriers had a 1.85-fold increased risk of SVO disorder (OR=1.85, 95% CI=1.01-3.33, p=0.04). When analysing the association between the haplotype related to rs2738446 and rs2738450 and SVO disorder, the most common haplotype allele CC was used as the reference, and the GA haplotype allele was associated with a 48% decreased risk of SVO disorder (OR=0.52; 95% CI=0.29-0.93, p=0.029). Haplotype-based analysis of LDLR in Taiwanese patients with cerebral infarction provided preliminary evidence suggesting that genetic polymorphisms of LDLR can modify the stroke presentation.

Baclofen successfully abolished prolonged central hyperthermia in a patient with basilar artery occlusion.

Hyperthermia, not uncommon in severe brainstem stroke, is frequently difficult to control and associated with a poor prognosis and high mortality. Successful treatment of central hyperthermia in patients with brainstem infarction by baclofen has not been described. Following basilar artery occlusion, a 68-year-old female developed prolonged hyperthermia. Her hyperthermia did not respond to any antipyretic treatments. A water-cooling blanket was utilized to control her hyperthermia; however, body temperatures fluctuated at a range of 35.5-40.0 degrees C. After given baclofen 30 mg/day, her body temperatures returned to a normal range and remained stable. Hyperthermia following severe brainstem infarction without any sign of infection or inflammatory sources usually comes from a central origin and is likely associated with dysfunctions of the thermoregulatory system. Baclofen may be one of the treatment choices in patients with neurogenic central hyperthermia.

Periictal magnetic resonance imaging in status epilepticus.

PURPOSE: To determine the changes of magnetic resonance imaging (MRI) during the periictal phase in status epilepticus (SE). PATIENTS AND METHODS: We identified 15 patients diagnosed of status epilepticus with corresponding MRI changes, including 11 patients with generalized convulsive status epilepticus (GCSE), 2 with complex partial status epilepticus (CPSE), and 2 with simple partial status epilepticus (SPSE). All MRI changes, corresponding electroencephalogram, and prognosis were evaluated. RESULTS: Regional cortical lesions were observed on MRI, including restricted diffusion in diffusion-weighted images (DWIs) (11 out of 15) and hyperintense signal change in fluid-attenuated inversion recovery (FLAIR) images (12 out of 15) with hypervascularity and parenchymal swelling. The remote lesions included crossed cerebellar diaschisis (3 patients), ipsilateral thalamic lesion (4 patients), and basal ganglia lesions (3 patients). Although the periictal MRI changes were usually reversible, irreversible changes were also found, especially in GCSE, such as focal brain atrophy, cortical laminar necrosis, and mesial temporal sclerosis. GCSE patients with periodic epileptic form discharges had higher possibilities of widespread MRI abnormalities and poor prognosis in the future. CONCLUSIONS: In this study, DWIs and FLAIR images were proved useful in determining the extent and severity of early neuronal damage caused by epileptic discharges in SE patients. Seizure-induced long-term injuries were also observed in the follow-up MRI.

Risk factors and subtype analysis of acute ischemic stroke.

BACKGROUND AND PURPOSE: Stroke risk factors and subtypes were examined for associations with mortality and recurrence rate in Taiwanese patients with first-ever and recurrent stroke. METHODS: This study examined patients with initial and recurrent stroke from 2003 to 2005 for risk factors, demographic data, Bamford subtypes and transient ischemic attack. RESULTS: One thousand and twenty-one patients with 1,085 stroke episodes were recruited. Significant factors associated with recurrent stroke were hyperlipidemia, atrial fibrillation and smoking. A significant incidence of lacunar infarction was noted in the patient population (37.82% in all patients; 41.02% in first stroke vs. 35.67% in recurrent stroke patients). Patients with diabetes mellitus were more likely to have lacunar rather than total anterior circulation infarction (TACI) or partial anterior circulation infarction (PACI). Hyperlipidemia was more often attributable to lacunar stroke than PACI. Atrial fibrillation was significantly associated with nonlacunar infarcts, TACI and PACI but not lacunar stroke. CONCLUSIONS: The incidence of lacunar infarction was significantly higher in initial rather than recurrent stroke patients. Diabetes mellitus or hyperlipidemia was highly associated with lacunar infarction. Atrial fibrillation was associated with nonlacunar infarction in Taiwan, similar to the result of White and Black populations in the UK.

Hypoalbuminemia and not hyperhomocysteinemia as a risk factor for dementia in hemodialysis patients.

BACKGROUND: The most common causes of morbidity and mortality in uremic patients are cardiovascular disease and central nervous system dysfunction. However, the exact causes of dementia in uremic patients remain unclear. This study attempted to determine which risk factors are associated with dementia in hemodialysis patients. METHODS: In total, 147 chronic uremic patients receiving regular hemodialysis treatment were recruited. Data for risk factors regarding cardiovascular disease and dementia, such as hypertension, diabetes mellitus, smoking, age, illiteracy, serum levels of albumin, cholesterol, triglycerides, and homocysteine, and liver function, were recorded. The Mini-Mental Status examination was used to assess mental function, and the Hachinski ischemic scale was applied to differentiate among dementia types. The diagnosis of dementia was based on criteria from the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition. RESULTS: Twenty-six patients were diagnosed as manifesting dementia. Of all patients with dementia, 21 had a Hachinski score of 0 to 4, and 5 had a score of 7 to 10. In a multiple logistic regression analysis, low serum albumin and illiteracy were significantly associated with dementia. However, no difference existed between the two groups in terms of homocysteine levels. CONCLUSIONS: This study demonstrated that uremic patients were prone to nonvascular dementia. We conclude that hypoalbuminemia and not hyperhomocysteinemia is a risk factor for dementia in hemodialysis patients.

Carotid ultrasound criteria for detecting intracranial carotid stenosis.

BACKGROUND/AIMS: This study attempted to establish carotid ultrasound criteria for identifying stenosis of the intracranial internal carotid artery (ICA) and middle cerebral artery (MCA). METHODS: Two hundred and fifty-five patients were enrolled. Ultrasound measurements for common carotid artery (CCA) and ICA were as follows: flow volume (FV), peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI) and resistance index (RI). The sensitivity and specificity of the ultrasound criteria for determining intracranial ICA or MCA>or=50% stenosis were calculated. RESULTS: The criteria identified for detecting intracranial ICA>or=50% stenosis were ICA FV<159 ml/min, ICA PSV<33 cm/s and CCA PSV<42 cm/s. When ICA PSV<33 cm/s was combined with CCA PSV<42 cm/s, sensitivity increased to 82%, with 91% specificity. The criteria identified for detecting MCA>or=50% stenosis were CCA FV<285 ml/min, ICA FV<179 ml/min, ICA PSV<33 cm/s, >35% reduction in FV in the CCA, >40% reduction in FV in ICA, and >35% reduction in PSV in ICA. When these criteria were combined, sensitivity increased to 69%, with 85% specificity. CONCLUSION: This study demonstrated that ultrasound criteria are sensitive and specific for detecting intracranial ICA and MCA significant obstruction.

Massive pontine hemorrhagic transformation associated with an anticoagulant for basilar artery occlusion.

Symptomatic hemorrhagic transformation is common in supratentorial and cerebellar infarction, but is rare in brainstem infarction. It is seldom reported in basilar artery occlusion. Although early arterial recanalization by thrombolytic agent has became the new trend of treatment, for some neurologists anticoagulant is still a conventional alternative treatment of basilar artery occlusion, especially in longer-existing ischemic deficits. We report a case of massive pontine hemorrhage associated with enoxaparin (low-molecular-weight heparin) treatment for basilar artery occlusion. On the basis of the clinical information and neuroimaging, an embolism was the most likely cause of stroke. The case presented herein adds massive pontine hemorrhagic transformation to the list of possible complications of anticoagulants for basilar artery occlusion. Apart from no evidence-based benefit in treatment of basilar artery occlusion, anticoagulant may contribute to devastating hemorrhagic transformation.

Cooperative multiagent congestion control for high-speed networks.

An adaptive multiagent reinforcement learning method for solving congestion control problems on dynamic high-speed networks is presented. Traditional reactive congestion control selects a source rate in terms of the queue length restricted to a predefined threshold. However, the determination of congestion threshold and sending rate is difficult and inaccurate due to the propagation delay and the dynamic nature of the networks. A simple and robust cooperative multiagent congestion controller (CMCC), which consists of two subsystems: a long-term policy evaluator, expectation-return predictor and a short-term rate selector composed of action-value evaluator and stochastic action selector elements has been proposed to solve the problem. After receiving cooperative reinforcement signals generated by a cooperative fuzzy reward evaluator using game theory, CMCC takes the best action to regulate source flow with the features of high throughput and low packet loss rate. By means of learning procedures, CMCC can learn to take correct actions adaptively under time-varying environments. Simulation results showed that the proposed approach can promote the system utilization and decrease packet losses simultaneously.