Hypertension Research (2015) 38, 291–297 & 2015 The Japanese Society of Hypertension All rights reserved 0916-9636/15 www.nature.com/hr ORIGINAL ARTICLE Endothelial dysfunction is associated with the severity of cerebral small vessel disease Tomohisa Nezu1, Naohisa Hosomi1, Shiro Aoki1, Satoshi Kubo1, Mutsuko Araki1, Tomoya Mukai1, Tetsuya Takahashi1, Hirofumi Maruyama1, Yukihito Higashi2 and Masayasu Matsumoto1 The pathogenesis of cerebral small vessel disease, a disease that involves white matter lesions (WMLs) and cerebral microbleeds (CMBs), is thought to be associated with endothelial dysfunction. Flow-mediated dilation (FMD) has been used to measure endothelium-dependent vasodilation. The aim of this study was to investigate the association between endothelial function (as measured by FMD) and cerebral small vessel disease. Patients with a history of cerebrovascular disease and comorbidities were enrolled in this study (n = 102; 69 males, 70.1 ± 9.2 years). The patients were divided into two groups according to the severity of WMLs, which were assessed by Fazekas classification; grades 0 to 1 as mild WMLs group and grades 2 to 3 as severe WMLs group. A gradient-echo MRI was performed in 96 patients (94.1%) to evaluate whether CMBs were present. The patients in the severe WMLs group (n = 40) were older (P = 0.001), more frequently exhibited hypertension (P = 0.045) and diabetes mellitus (P = 0.026) and possessed lower FMD values (Po0.001) than the patients in the mild WMLs group (n = 62). CMBs were observed in 30 patients (31.3%). Using receiver operating characteristic curves, the optimal FMD cutoff values for predicting the presence of severe WMLs and CMBs were 3.9% and 3.7%, respectively. On multivariate logistic analysis, FMD o4.0% (odds ratio 9.50; 95% confidence interval 3.55–28.83) was independently associated with severe WMLs. Additionally, FMD o3.8% (5.82; 2.23–16.50) was also associated with the presence of CMBs. Endothelial dysfunction as evaluated by FMD may be predictive of the severity of cerebral small vessel disease. Hypertension Research (2015) 38, 291–297; doi:10.1038/hr.2015.4; published online 12 February 2015 Keywords: cerebral microbleeds; cerebral small vessel disease; endothelial dysfunction; white matter lesions INTRODUCTION The ultrasonographic assessment of brachial artery flow-mediated Cerebral small vessel diseases such as white matter lesions (WMLs), dilation (FMD) is a noninvasive and useful method that has been lacunar infarcts and cerebral microbleeds (CMBs) are known to recently used to measure endothelium-dependent vasodilation.13 – cause cognitive impairment, dementia and disability.1 3 Additionally, Several studies have reported that impaired FMD occurs in patients with cerebral small vessel diseases have an elevated patients with coronary artery disease and cardiovascular risk long-term risk of stroke recurrence and unfavorable stroke factors.14–17 Furthermore, a recent systematic review and meta-analysis outcomes.4,5 The pathological changes associated with cerebral small showed that impaired FMD is a predictor of future cardiovascular vessel disease include arteriosclerosis, fibrinoid necrosis and events.18 However, little is known about the relationship between – lipohyalinosis.6 8 These changes lead to cerebral parenchymal damage cerebral small vessel disease and FMD. A study involving 25 older that is both ischemic and hemorrhagic and based on mechanisms such patients with cardiovascular disease reported that the severity of FMD as chronic hypoperfusion and damage to the blood–brain barrier.9,10 is related to the volume of the WMLs.19 However, it is unclear The pathogenesis of cerebral small vessel disease is thought to be whether FMD is also associated with the presence of CMBs and associated with endothelial dysfunction and inflammation.11,12 The other biological findings such as inflammation and altered glucose and severity of this disease is frequently evaluated with neuroimaging lipid levels. techniques such as MRI. Surrogate markers associated with endothelial The aim of this study was to investigate the association between dysfunction and inflammation that can be used to evaluate the endothelial function (evaluated by FMD) and the severity of cerebral pathophysiology and therapeutic effects of cerebral small vessel disease small vessel disease in patients with chronic cerebrovascular disease are necessary. and comorbidities. 1Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan and 2Department of Cardiovascular Regeneration and Medicine, Research Center for Radiation Genome Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan Correspondence: Dr T Nezu, Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. E-mail: [email protected] Received 28 September 2014; revised 9 December 2014; accepted 24 December 2014; published online 12 February 2015 Relationship between FMD and cerebral small vessel TNezuet al 292 METHODS 75-μg tablet of nitroglycerin was administered sublingually to the patient, and Subjects images of the artery were recorded continuously for 8 min. The NMD was This was a single-center hospital-based prospective study. The study protocol automatically calculated as the percent change of the peak vessel diameter from was governed by the guidelines of the national government based on the the baseline value; %NMD (peak diameter − baseline diameter/baseline dia- Helsinki Declaration revised in 1983. The study was approved by the meter) was used for the analysis. A single investigator (TN) who was unaware Institutional Research and Ethics Committee of our hospital. All of the patients of the clinical details of the patient performed the FMD and NMD evaluations provided written informed consent to participate in the study. Patients with of all of the patients. The intra-observer coefficients of variation were 1.2% for cerebrovascular disease (at least 6 months after the stroke onset) and other the baseline brachial artery diameter among all patients and 11.1% for the FMD atypical neurological problems who were undergoing a clinically indicated in 18 randomly selected patients. ultrasonographic examination of their carotid artery systems were enrolled between November 2012 and April 2014 at the Hiroshima University Hospital. Magnetic resonance imaging All of the patients underwent MRI, carotid ultrasonography and FMD studies. An MRI was performed with a 1.5 T scanner (SIGNA, GE Medical Systems, Baseline clinical characteristics, including age, sex, hypertension, diabetes Fairfield, CT, USA or Magneton Symphony Advanced or Avanto, Siemens mellitus, dyslipidemia, atrial fibrillation, renal dysfunction, history of stroke Medical Systems, Erlangen, Germany) or a 3.0 T scanner (SIGNA). The (ischemic or hemorrhagic), coronary artery disease and current smoking status imaging protocol consisted of a T1-weighted spin-echo, a T2-weighted spin- were recorded. In addition to obtaining a medical history, relevant risk factors echo and fluid-attenuated inversion recovery. The severity of WMLs was rated were identified from a self-reported medical history or inferred from medica- visually from the fluid-attenuated inversion recovery images using the Fazekas tions prescribed by the primary physician. Criteria for hypertension, diabetes scale as follows: no lesions (grade 0), punctate lesions (grade 1), early confluent mellitus and dyslipidemia were previously defined.20 Renal functioning was lesions (grade 2) and confluent lesions (grade 3).26 The patients with WMLs of calculated with the estimated glomerular filtration rate (eGFR) using a revised grades 0 to 1 were assigned to the mild WMLs group, and those with WMLs of − equation for the Japanese population as follows: eGFR (ml min 1 grades 2 to 3 were assigned to the severe WMLs group. Additionally, a gradient- − − − 1.73 m 2) = 194 × (serum creatinine) 1.094 ×(age)0.287 × 0.739 (for echo T2*-weighted MRI (GRE) was performed to evaluate the presence of − women).21 Renal dysfunction was defined as an eGFR o60 ml min 1 1.73 CMBs. CMBs were defined as homogeneous round lesions with diameters − m 2. Stroke subtypes were assessed according to the Trial of Org 10172 in ⩽ 10 mm characterized by signal intensity loss as shown by the GRE. The Acute Stroke Treatment (TOAST) category.22 The carotid ultrasonography, locations of CMBs were classified as follows: lobar (cortex, subcortex and white FMD study and blood sample collection were performed in the morning on the matter), deep (basal ganglia, thalamus, brain stem and cerebellum) and mixed same day. The MRI study was performed within 3 months before or after the (both lobar and deep). Lesions exhibiting signal intensity loss in the globus day when the FMD study was performed. pallidus or subarachnoid space and diffuse axonal injury were excluded based on appearance or clinical history.27 Two stroke neurologists (TN and MA) who Carotid ultrasonography were unaware of the clinical details of the patients graded the severity of the The common carotid arteries (CCAs) were evaluated using high-resolution WMLs and identified CMBs, respectively. B-mode duplex ultrasonography with a 7.5-MHz linear-type probe (Aplio, Toshiba Medicals, Tokyo, Japan). Bilateral optimal visualization of the carotid Statistical analysis artery was performed with the patients