Cerebral blood flow and metabolism associated with cerebral microbleeds in small vessel disease.

OBJECTIVE: Cerebral microbleeds (CMBs), probably reflecting microangiopathy, have not yet sufficiently been examined in association with cerebral blood flow (CBF) and metabolism. We investigated the relationships between CMBs, and CBF and metabolism in symptomatic small vessel disease. METHODS: We enrolled 22 patients with symptomatic small vessel disease without severe stenosis (>50 %) in major cerebral arteries. Volumes of white matter lesions (WMLs) and number of CMBs were assessed on images of fluid-attenuated inversion recovery and gradient-echo T2*-weighted magnetic resonance imaging, respectively. Patients were divided into two groups according to the median number of CMBs (group I <5, n = 10; group II ≥5, n = 12). Parametric images of CBF, cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction and cerebral blood volume were estimated using positron emission tomography and (15)O-labeled gases. The functional values in the cortex-subcortex, basal ganglia, and centrum semiovale were compared between the two groups. RESULTS: Volumes of WMLs of group II were larger than those of group I (median: 38.4; range: 25.1-91.5 mL vs. median: 11.3; range: 4.2-73.4 mL, p = 0.01). In the centrum semiovale, the mean CBF of group II was significantly lower than that of group I (12.6 ± 2.6 vs. 15.6 ± 3.3 mL/100 g/min, p = 0.04). In the other regions, there were no significant differences in either CBF or CMRO2 between the two groups. CONCLUSIONS: Our study indicated that increases in the number of CMBs with larger volumes of WMLs were associated with cerebral ischemia in the deep white matter in patients with symptomatic small vessel disease.

Which should be the essential components of stroke centers in Japan? A survey by questionnaires sent to the directors of facilities certified by the Japan stroke society.

BACKGROUND: We conducted a survey by questionnaire to identify the essential components of stroke centers in Japan and compared our results with the European Expert Survey. METHODS: In 2007, a questionnaire was mailed to the directors of 740 facilities certified by the Japan Stroke Society to ask their opinion on the essential components of comprehensive stroke centers (CSC), primary stroke centers (PSC) and any hospital ward (AHW) admitting acute stroke patients. The directors were asked to provide 1 of the following 6 possible answers regarding 112 components: 'irrelevant'; 'useful but not necessary'; 'desirable'; 'important but not absolutely necessary'; 'absolutely necessary', or 'question unclear or ambiguous'. The components considered 'absolutely necessary' by more than 75% of the respondents were compared between our survey and the European Expert Survey. In addition, we compared the rates of neurosurgeons and neurologists who answered 'absolutely necessary' with regard to each component. RESULTS: Responses were obtained from 428 directors (57.8% response rate). Among these respondents, 298 (69.6%) were neurosurgeons. There was no component considered 'absolutely necessary' for AHW by more than 75% of the respondents, and this was similar to the results of the European Expert Survey. The following components were considered 'absolutely necessary' for PSC in our survey: brain CT scanning 24 h a day, 7 days a week (24/7); automated monitoring of the ECG, pulse oximetry, blood pressure and breathing, and respiratory support. In both our survey and the European Expert Survey, the essential components for CSC were as follows: physiotherapist; brain CT scanning 24/7; monitoring of the ECG, pulse oximetry and blood pressure; carotid surgery; angioplasty and stenting, and intravenous recombinant tissue plasminogen activator protocols. The components multidisciplinary stroke team, stroke-trained nurse, ultrasonography, collaboration with an outside rehabilitation center, stroke pathway and clinical research were deemed essential only in the European Expert Survey. However, MRI 24/7, MR angiography 24/7, conventional angiography 24/7, respiratory support as well as most neuroendovascular and neurosurgical treatments were considered necessary for CSC by more than 75% of the respondents in our survey. Analyzing the responses from only neurologists reduced the differences between our survey and the European Expert Survey. CONCLUSIONS: The present study indicated the essential components expected for stroke centers in Japan. Our survey demonstrated that more emphasis was likely to be placed on installations than on a dedicated stroke team and the use of stroke care maps. In addition, the results of this study may reflect some characteristics of the stroke care environment in Japan, such as the predominance of neurosurgeons and widespread use of MRI.

Preserved acetazolamide reactivity in lacunar patients with severe white-matter lesions: 15O-labeled gas and H2O positron emission tomography studies.

Limited evidence exists on the relationships between severity of white-matter lesions (WMLs) and cerebral hemodynamics in patients without major cerebral artery disease. To examine changes of cerebral blood flow (CBF), oxygen metabolism, and vascular reserve capacity associated with severity of WML in patients with lacunar stroke, we used a positron emission tomography (PET). Eighteen lacunar patients were divided into two groups according to the severity of WMLs, assessed by Fazekas classification; grades 0 to 1 as mild WML group and grades 2 to 3 as severe WML group. Rapid dual autoradiography was performed with (15)O-labeled gas-PET followed by (15)O-labeled water-PET with acetazolamide (ACZ) challenge. Compared with the mild WML group, the severe WML group showed lower CBF (20.6±4.4 versus 29.9±8.2 mL/100 g per minute, P=0.008), higher oxygen extraction fraction (OEF) (55.2±7.4 versus 46.7±5.3%, P=0.013), and lower cerebral metabolic rate of oxygen (CMRO(2)) (1.95±0.41 versus 2.44±0.42 mL/100 g per minute, P=0.025) in the centrum semiovale. There were no significant differences in the ACZ reactivity between the two groups (48.6±22.6% versus 42.5±17.2%, P=0.524). Lacunar patients with severe WMLs exhibited reduced CBF and CMRO(2), and increased OEF in the centrum semiovale. The ACZ reactivity was preserved in both patients with severe and mild WMLs in each site of the brain.

Medial medullary infarction identified by diffusion-weighted magnetic resonance imaging.

OBJECTIVE: To elucidate the frequency and clinical profiles of patients with medial medullary infarction (MMI) identified by diffusion-weighted MRI (DWI). METHODS: We assessed the frequency, radiological findings, etiology and clinical features of MMI detected by DWI from our single-center registry of acute ischemic patients. RESULTS: Thirty patients (1.5% of 2,014 with ischemic stroke) had MMI, including isolated unilateral MMI in 26 patients. Lesions were located by DWI in the rostral medulla of 25 patients (83%). Culprit infarcts that were undetectable by DWI in 6 (38%) of 16 patients who were assessed within 24 h after onset were later confirmed as MMI. The major etiological mechanism was small artery occlusion (SAO; 19 patients) and the median initial National Institutes of Health Stroke Scale score was 4 (interquartile range: 3-4.75). The most frequent symptom was contralateral hemiparesis (27 patients). None of the patients fulfilled the classical Dejerine Triad. Twenty-two patients (73%) had a modified Rankin Scale score of ≤2 at 3 months. A patient developed transient ischemic attack within 3 months; none developed recurrent stroke. CONCLUSIONS: Rostral medullary infarction with mild neurological deficits resulting from SAO is relatively frequent. Because emergency DWI within 24 h could not detect MMI in one third of the patients, this type of infarction could be misdiagnosed as capsular/pontine lacunae or other neurological disorders.

Progress of leukoaraiosis is inhibited by correction of platelet hyper-aggregability.

BACKGROUND: Platelet hyper-aggregability is an important risk factor for leukoaraiosis. In this study we investigated whether aggravation of leukoaraiosis can be controlled by means of long-term correction of platelet hyper-aggregability. METHODS: Twenty-one patients with leukoaraiosis and uncorrected platelet hyper-aggregability were compared with 21 controls matched for age, grade of leukoaraiosis and observation period whose platelet hyper-aggregability was corrected. Platelet aggregability was estimated by an optical analytical method with a nine-stage display using two different concentrations each of adenosine diphosphate (ADP) and collagen (the double ADP method). RESULTS: The mean observation period between two magnetic resonance imaging (MRI) scans for both groups was 4.1 years. In the non-corrected group, moderate to severe aggravation of leukoaraiosis was observed in a large number of patients. In the corrected group, only a small number of patients showed generally mild aggravation of leukoaraiosis. The number of patients showing aggravation of periventricular hyperintensity (PVH) was 7 in 21 in the non-corrected group versus 1 in 21 (p = 0.022) in the corrected group, and for aggravation of deep white-matter hyperintensity, these values were 9 in 21 versus 4 in 21, respectively. Thus, the difference was more significant if the degree of aggravation was taken into account. CONCLUSION: The progress of leukoaraiosis is greatly inhibited by long-term correction of platelet hyper-aggregability.