Single Subcortical Infarction Research Articles

Cavitation of symptomatic acute single small subcortical infarctions.

To investigate cavitation of symptomatic acute single small subcortical infarctions (SSSI). Acute SSSI were diagnosed with magnetic resonance (MR) diffusion-weighted imaging (DWI) combined with apparent diffusion coefficient (ADC) sequence on follow-up MR imaging. Cavitation of the acute SSSI was comprehensively viewed on FLAIR, T2-, and T1-weighted sequences. We enrolled 123 patients with acute SSSI. The follow-up median interval was 303 (125-390) days. The lesions of SSSI evolved into cavitation in 93 patients (75.6%), evolved into WMHs in nine patients (7.3%), and were no visible in 21 patients (17.1%). Cavitation was independently associated with larger infarct diameter on baseline DWI [odds ratio (OR), 1.250, 95% CI (1.078-1.451), P= 0.003], higher score of baseline old lacunar infarct [OR 3.44, 95% CI (1.49-7.91), P= 0.004], and lower rate of dyslipidemia [OR 0.30, 95% CI (0.10-0.76), P= 0.013]. Cavitation occurred more in the setting of small vessel diseased brain and less in the SSSI of possible atherosclerotic etiology. This suggested that the etiology of infarct was associated with cavitation after acute SSSI.

Characteristics of single subcortical small infarction in the middle cerebral artery territory

Objective: To investigate the characteristics and possible mechanisms of differtent stroke patterns of single subcortical small infarction (SSSI) in the middle cerebral artery (MCA) territory. Methods: The clinical and imaging data of patients with acute SSSI in MCA territory admitted to the Neurology Department of People's Hospital of Zhengzhou City from January 2016 to December 2017 were retrospectively analyzed. According to the presence of MCA stenosis and whether the lesion sites on axial DWI-MRI involved the lowest basal ganglia, SSSl were divided into different patterns. The clinical and imaging characteristics of patients with different stroke patterns were compared. Results: Of the 91 patients, 24 (26.37%) were SSSI with parental artery disease (SSSIPAD), 28 (30.77%) were proximal SSSI without PAD (pSSSI-PAD) and 39 (42.86%) were distal SSSI without PAD (dSSSI-PAD). There were significant differences in age, hypertension, diabetes mellitus, smoking, NIHSS score, low density lipoprotein cholesterin (LDL-C) level, infarct layers ≥3, lesion diameter, white matter hyperintensity, lacunar infarction, enlarged perivascular space, cerebral microbleed, concomitant intracranial and extracranial atherosclerotic stenosis among the three groups (all P<0.05). Compared with SSSIPAD(-), patients with SSSIPAD(+) had significantly higher prevalence of smoking, proximal SSSI, ICAS, ECAS, NIHSS score, LDL-C level and larger lesion diameter (all P<0.05). Conclusions: The clinical characteristics and imaging features were different among different SSSI stroke patterns. SSSIPAD is an important infarct type. pSSSI-PAD may showed intermediate features of SSSIPAD and dSSSI-PAD, and evidence of atherosclerosis should be carefully searched for such patients.

Branch atheromatous disease diagnosed as embolic stroke of undetermined source: A sub-analysis of NAVIGATE ESUS

Branch atheromatous disease (BAD) is distinctive from large and small arterial diseases, which is single subcortical infarction larger than lacunar stroke in the territories of deep perforators without relevant arterial stenosis. BAD meets the current criteria of embolic stroke of undetermined source. We performed an exploratory analysis of BAD in patients recruited to NAVIGATE embolic stroke of undetermined source, a randomized controlled trial to compare rivaroxaban and aspirin in embolic stroke of undetermined source patients. Among 3972 stroke patients in cerebral hemispheres with intracranial arterial imaging, 502 (12.6%) patients met the criteria for BAD. BAD was associated with younger age (years; OR: 0.97, 95% CI: 0.96-0.98), race (Asian; OR: 1.78, 95% CI: 1.44-2.21), region (Eastern Europe; OR: 2.49, 95% CI: 1.87-3.32), and higher National Institute of Health Stroke Scale (OR: 1.17, 95% CI: 1.12-1.22) at randomization. During follow-up, stroke or systemic embolism (2.5%/year vs. 6.2%/year, p = 0.0022), stroke (2.1%/year vs. 6.2%/year, p = 0.0008), and ischemic stroke (2.1%/year vs. 5.9%/year, p = 0.0013) occurred less frequently in BAD than non-BAD patients. There were no differences in annual rates of stroke or systemic embolism (2.5%/year vs. 2.5%/year, HR: 1.01, 95% CI: 0.33-3.14) or major bleeding (1.3%/year vs. 0.8%/year, HR: 1.51, 95% CI: 0.25-9.05) between rivaroxaban and aspirin groups among BAD patients. BAD was relatively common, especially in Asian and from Eastern Europe among embolic stroke of undetermined source patients. Stroke severity was higher at randomization but recurrence of stroke was fewer in BAD than non-BAD patients. The efficacy and safety of rivaroxaban and aspirin did not differ among BAD patients.

Consecutive Slides on Axial View Is More Effective Than Transversal Diameter to Differentiate Mechanisms of Single Subcortical Infarctions in the Lenticulostriate Artery Territory.

Objective: Lipohyalinosis or atherosclerosis might be responsible for single subcortical infarctions (SSIs); however, ways of differentiating between the two clinically remain uncertain. We aimed to investigate whether consecutive slides on axial view or transversal diameter is more effective to differentiate mechanisms by comparing their relationships with white matter hyperintensities (WMHs).Methods: All the participants from the Standard Medical Management in Secondary Prevention of Ischemic stroke in China (SMART) cohort who had SSIs in the lenticulostriate artery territory were included and categorized according to consecutive slides on axial view (≥4 consecutive slices or not) and transversal diameter (≥15 mm or not). The associations between the severity of WMHs and the different categories were analyzed.Results: Among the 3,821 patients of the SMART study, 281 had diffusion-weighted image-proven SSIs in the lenticulostriate artery territory. When classified by consecutive slides on axial view, SSIs on ≥4 slices were significantly associated with the severity of the WMHs, both in deep WMH (DWMH) (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.11–0.97; p = 0.04) and periventricular hyperintensity (PVH) (OR, 0.37; 95% CI, 0.17–0.78; p = 0.01). No such association was found on the basis of the transversal diameter (p > 0.1).Conclusion: Consecutive slides on axial view (≥4 consecutive slices) might be more effective than transversal diameter to identify the atherosclerotic mechanisms of SSIs in the lenticulostriate artery territory.Clinical Trial Registration: http://www.clinicaltrials.gov. Unique identifier: NCT00664846

Cardioembolic Sources in Patients With Small Single Subcortical Infarcts.

Transthoracic echocardiogram (TTE) is widely used as part of the work-up for ischemic stroke. However, the added utility of TTE in the management of small single subcortical infarcts (SSSI) has not been extensively evaluated. Therefore, we aimed to determine the frequency of high-risk and medium-risk cardioembolic sources diagnosed by TTE in SSSI patients, and whether the findings altered clinical management. We performed a retrospective analysis of a prospective cohort of patients with confirmed acute ischemic stroke enrolled in a single-center observational registry between August 2012 and July 2014. We assessed infarct topography on brain magnetic resonance imaging, blinded to final stroke subtype and treatment, to identify patients with SSSI. We defined SSSI as lesions in the corona radiata, basal ganglia, thalamus, or brainstem measuring <1.5 cm in maximal diameter. We excluded patients with atrial fibrillation and large artery stenosis >50%, and assessed the frequency of cardioembolic sources found by TTE in the remaining patients. Among 908 patients, 75 (8.3%) had SSSI, of which 4 (5.3%) had atrial fibrillation and 6 (8%) had symptomatic large artery stenosis. TTE revealed cardiac abnormalities in 46% of the remaining patients (mean age: 65.1 y, 52% female, 58% white). The most common findings were dilated left atrium (29%), patent foramen ovale (14%), and atrial septal aneurysm (7.7%). Anticoagulants were prescribed in 3 (4.6%) patients on the basis of TTE results. TTE identified potential cardioembolic sources in almost half of the patients, but altered antithrombotic management in only 5% of patients with SSSI.

Plaque Distribution and Characteristics in Low-Grade Middle Cerebral Artery Stenosis and Its Clinical Relevance: A 3-Dimensional High-Resolution Magnetic Resonance Imaging Study

The significance of atherosclerotic plaques in the parental artery with low-grade stenosis remains undetermined. We used three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI) to investigate plaque distribution and characteristics of low-grade middle cerebral artery (MCA) stenosis and its clinical relevance with stroke events. We retrospectively studied 22 symptomatic patients and 24 asymptomatic patients with low-grade MCA stenosis (<50%). By 3D HR-MRI, each identified plaque was classified as either culprit (plaque on the ipsilateral side of a stroke) or nonculprit (plaques in asymptomatic patients or not within the vascular territory of a stroke). Plaque enhancement grades and distribution were assessed and compared between the groups. The association between plaque enhancement and distribution and ischemic stroke was evaluated. We identified 22 culprit plaques and 31 nonculprit plaques. More culprit plaques showed contrast enhancement compared to the nonculprit plaques (95.5% versus 29.0%, P <.001). Culprit plaques were more frequently superiorly distributed than the nonculprit plaques (46.9% versus 17.5%, P <.01). Contrast enhancement (odds ratio [OR] 17.0, 95% confidence interval [CI] 3.7-77.4) and superior distribution (OR 4.2, 95% CI 1.4-12.1) of a plaque were associated with a recent ischemic stroke, of which single subcortical infarctions accounted for the largest percentage (50%). Contrast enhancement and superior distribution may serve as indicators of culprit plaques in low-grade MCA stenosis, and they were significantly related to a recent ischemic stroke.

Single Subcortical Infarct: Pathomechanism Assessed by Thin-Section Computed Tomography Perfusion

The pathomechanism of a single subcortical infarct (SSI) may be better determined by assessing the perfusion status between parent artery and ischemic lesion. We aimed to compare the classifications into branch atheromatous disease (BAD) versus non-BAD based on diffusion-weighted imaging (DWI) or computed tomography perfusion (CTP), and to test whether a CTP-based classification improves the predicting power for progression in SSI (PSSI) compared to that by DWI. We enrolled 109 consecutive patients with SSI examined by whole-supratentorial brain CTP and follow-up DWI. Time-to-drain (TTD) maps were calculated from 1-mm dynamic CTP data. BAD was assumed when either the ischemic lesion extended to the basal surface of the parent artery on axial DWI or the hypoperfused area (TTD ≥ 5 seconds) was <5 mm apart from the cerebrospinal fluid perforators interface on both coronal and sagittal CTPs. We tested the relationship between DWI and CTP for determining BAD, and compared demographics, imaging, and the frequency of PSSI between the BAD and non-BAD based on CTP. Multivariable regression analysis was performed to determine predicting factors for PSSI. On DWI, 66 of 109 patients (60.6%) were classified as BAD; on CTP, 32 patients were classified as BAD (29.4%), showing significant difference (P = .047). PSSI was significantly different between BAD versus non-BAD by CTP (40.6% versus 11.7%, P = .002), but not different by DWI (21.2% versus 18.6%, P = .930). BAD-type perfusion was the only independent predictor for PSSI (OR, 5.209; 95% CI, 1.745-15.555; P = .003). The classifications of SSI with and without BAD by CTP and DWI are significantly different. CTP may help to predict PSSI.

Abstract WMP18: Assessment of Perfusion Pattern Can be Useful for Predicting the Progression of Lacunar Infartion

Background and Purpose: The pathomechanism of a single subcortical infarct (SSI) may be better determined by assessing the perfusion status between parent artery and ischemic lesion. We aimed to compare the classifications into branch atheromatous disease (BAD) versus non-BAD based on DWI or CTP and to test whether a CTP-based classification improves the predicting power for progression in SSI (PSSI) compared to that by DWI. Methods: We enrolled 93 consecutive patients with SSI examined by whole-supratentorial brain CTP and follow-up DWI. Time-to-drain (TTD) maps were calculated from 1-mm dynamic CTP data. BAD was assumed when either the ischemic lesion extended to the basal surface of the parent artery on axial DWI or the hypoperfused area (TTD≥5 sec) was &lt;5mm apart from the CSF-perforators interface on both coronal and sagittal CTP. We tested the relationship between DWI and CTP for determining BAD, and compared demographics, imaging, and the frequency of PSSI between the BAD and non-BAD based on CTP. Multivariate regression analysis was performed to determine predicting factors for PSSI. Results: On DWI, 57 of 93 patients (61.3%) were classified as BAD; on CTP 28 patients (30.1%), showing significant difference ( P &lt;0.0001). PSSI was significantly different between BAD versus non-BAD by CTP (35.7% versus 12.3%, P =0.020), but not different by DWI (22.8% versus 13.9%, P =0.289). BAD-type perfusion was the only independent predictor for PSSI (OR, 5.242; 95% CI, 1.372-20.021; P =0.015). Conclusion: The classifications of SSI with and without BAD by CTP and DWI are significantly different. CTP may help to predict PSSI.

Examining Subcortical Infarcts in the Era of Acute Multimodality CT Imaging.

Lacunar infarct has been characterized as small subcortical infarct. It is postulated to occur from "in situ microatheroma or lipohyalinosis" in small vessel or lacunar mechanism. Based on this idea, such infarcts by lacunar mechanism should not be associated with large area of perfusion deficits that extend beyond the subcortical region to the cortical region. By contrast, selected small subcortical infarcts, as defined by MR imaging in the subacute and chronic stage, may initially have large perfusion deficit or related large vessel occlusions. These infarcts with "lacunar" phenotype may also be caused by disease in the parent vessel and may have very different stroke mechanism from small vessel disease. Our aim is to describe differences in imaging characteristics between patients with small subcortical infarction with "lacunar phenotype" from those with lacunar mechanism. Patients undergoing acute CT perfusion/angiography (CTP/CTA) within 6 h of symptom onset and follow-up magnetic resonance imaging (MRI) for ischemic stroke were included (2009-2013). Lacunar infarct was defined as a single subcortical infarct ≤20 mm on follow-up MRI. Presence of perfusion deficits, vessel occlusion, and infarct dimensions was compared between lacunar infarcts and other topographical infarct types. Overall, 182 patients (mean age 66.4 ± 15.3 years, 66% males) were included. Lacunar infarct occurred in 31 (17%) patients. Of these, 12 (39%) patients had a perfusion deficit compared with those with any cortical infarction (120/142, 67%), and the smallest lacunar infarct with a perfusion deficit had a diameter of <5 mm. The majority of patients with lacunar infarction (8/12, 66.7%) had a relevant vessel occlusion. A quarter of lacunar infarcts had a large artery stroke mechanism evident on acute CTP/CTA. Lacunar mechanism was present in 3/8 patients with corona radiata, 5/10 lentiform nucleus, 5/6 posterior limb of internal capsule (PLIC), 3/5 thalamic infarcts, 1/2 miscellaneous locations. There was a trend to significant with regards to finding lacunar mechanism among patients with thalamic and PLIC infarcts versus lentiform nucleus and corona radiata infarcts (p = 0.13). Diverse stroke mechanisms were present among subcortical infarcts in different locations. When available acute CTP/CTA should be combined with subacute imaging of subcortical infarct to separate "lacunar phenotype" from those with lacunar mechanism.

Increased arterial pulsatility and progression of single subcortical infarction.

We investigated the association of clinical, laboratory, sonographic and imaging parameters, in the progression of single subcortical infarctions. Consecutive 169 patients with lacunar (n = 89) and striatocapsular infarctions (n = 80) in the middle cerebral artery (MCA) territory with nonstenotic MCAs were recruited and examined for stroke progression. The pulsatility index (PI) was measured by transcranial Doppler from ipsilateral M1. The striatocapsular infarction group exhibited more stroke progression. The patients with progressive lacunar infarctions had more diabetes, higher HbA1c levels, and higher initial National Institutes of Health Stroke Scale (NIHSS) scores, and the patients with progressive striatocapsular infarctions had more hypertension, higher cholesterol levels, and higher NIHSS scores. The MCA PI was higher in the lacunar infarction patients with progression (0.99 ± 0.19 vs. 0.90 ± 0.14, p = 0.048), while the striatocapsular infarction patients did not differ according to progression. From a multivariate analysis, higher MCA PI were independently associated with lacunar infarction progression (by 0.1 increase, OR 1.51; 95% CI 1.06-2.15; p = 0.024). Higher pulsatility was associated with progression in lacunar infarction. PI measured by transcranial Doppler sonography might reflect downstream arterial resistance and vascular/paravascular perfusion status and be a possible indicator of stroke progression. • Higher pulsatility index was observed in progression group of lacunar infarction patients. • Higher pulsatility index seemed to be associated with progression in lacunar infarction patients. • Differences in the factors associated with stroke progression suggest different underlying pathophysiologies.

Abstract WP347: Clopidogrel Plus Aspirin in Patients With Different Types of Single Small Subcortical Infarction_Subgroup Analysis of CHANCE Trial

Objective: We aim to investigate the effects and safety of clopidogrel plus aspirin in patients with different types of single small subcortical infarction(SSSI) in the Clopidogrel in High-risk patients with Acute Non-disabling Cerebrovascular Events (CHANCE) trial. Methods: In this subgroup analysis, SSSI was defined as single DWI lesion of ≤2.0 cm and SSSI with stenosis of any degree of the parent artery was regarded as a SSSI+PAD. We assessed the interaction of the treatment effects of clopidogrel plus aspirin versus aspirin alone among patients with and without PAD. Efficacy was assessed by intention to treat analysis and safety was assessed in the on-treatment population. Results: A total of 338 patients with SSSI were included in the final analysis,105 with SSSI+PAD and 233 SSSI-PAD. In SSSI+PAD patients, 10.9% (5/46) had recurrent stroke in the clopidogrel-aspirin group as compared to 13.6% (8/59) in the aspirin group (adjusted hazard ratio, 0.66; 95% confidence interval, 0.20-2.20; P=0.50). In SSSI-PAD patients, 8.9% (11/124) had recurrent stroke in the clopidogrel-aspirin group as compared 7.3% (8/109) in the aspirin group (adjusted hazard ratio, 1.64; 95% confidence interval, 0.61- 4.38; P=0.32). The number of bleeding events was similar between the clopidogrel-aspirin group and aspirin group regardless of SSSI+PAD or SSSI-PAD. Conclusions: Although dual antiplatelet therapy did not significantly reduce the risk of recurrent stroke than aspirin alone in patients with SSSI. It was potentially beneficial to the patients with SSSI+PAD. Dual antiplatelet treatment did not increase the risk of bleeding in patients with any kind of SSSI.

Diffusion-Perfusion Mismatch in Single Subcortical Infarction: A Predictor of Early Neurological Deterioration and Poor Functional Outcome

Background/Aims: Early neurological deterioration (END) is frequently observed and related to poor functional outcome in patients with single subcortical infarction (SSI). We evaluated the role of diffusion-perfusion mismatch (DPM) as a predictor of END and functional outcome in patients with SSI. Methods: We retrospectively analyzed data for 274 patients with acute SSI. DPM was positive in the presence of a lesion on the perfusion map that was larger than that on the corresponding slice on diffusion-weighted imaging. END was defined as an increase of <1 points in the motor portion of the National Institute of Health Stroke Scale (NIHSS) within 72 h from MRI acquisition. Patients with a modified Rankin Scale (mRS) score of 3 or more at day 30 were considered having a poor functional outcome. Results: DPM was more frequently observed in the END (+) than in the END (-) group (21/35 (60.0%) vs. 50/239 (20.9%); p < 0.001). After adjusting for covariates, the presence of DPM and NIHSS score on admission were independently associated with END (DPM, OR 5.03, p < 0.001; NIHSS, OR 1.14, p = 0.033) and poor functional outcome (DPM, OR 2.44, p = 0.018; NIHSS, OR 1.48, p < 0.001). Conclusions: The DPM concept is applicable to prediction of END and functional disability in patients with SSI.

The shape of middle cerebral artery and plaque location: high-resolution MRI finding.

The location of plaque may be associated with the vascular geometry. We aimed to examine the relationship between the geometry of middle cerebral artery and the plaque location detected by high-resolution magnetic resonance imaging. Among patients with a single subcortical infarction without a significant middle cerebral artery stenosis on magnetic resonance angiography, those with a plaque detected from high-resolution magnetic resonance imaging were prospectively enrolled. The shape of middle cerebral artery was measured from the coronal view, and was classified as straight, U-shaped, inverted U-shaped, and S-shaped. The location of the plaque was divided into superior and inferior, and analyzed according to the shape of middle cerebral artery. Among the 40 patients, the shape of middle cerebral artery was straight in 7 (17·5%), U-shaped in 10 (15·0%), inverted U-shaped in 11 (27·5%), and S-shaped in 12 patients (30·0%). The superior plaque was more closely associated with straight (85·7%) or U-shaped middle cerebral arteries (90·0%), whereas inverted U-shaped (81·8%) and S-shaped middle cerebral arteries (75·0%) were more often associated with inferior plaque. The prevalence of symptomatic plaque was higher in superior than inferior plaques (70·0% vs. 25·0%, P = 0·004). Multivariate analysis showed that straight and U-shaped middle cerebral artery was the only significant factor associated with the superior plaque. The shape of middle cerebral artery may be a factor determining the location of early atherosclerotic plaque.

Abstract 23: Predictors of Early Neurological Deterioration in the Single Small Subcortical Infarctions

Background: Early neurological deterioration (END) occurs in ≥20% of single small subcortical infarctions (SSSIs; axial diameter ≤20 mm in the perforator territories) and deters functional recovery. SSSIs are supposed to have two distinct pathological processes including microvasculopathies of arteriolar walls and the localized atherosclerosis of the upstream arteries. We hypothesized that the occurrence of END in the SSSIs differs according to the pathological processes. Methods: From a total of 4961 stroke cases between July 2007 and July 2013, we assessed 587 patients with SSSI within 48 hours of onset. END was assessed prospectively as a quality improvement program of stroke care. Functional outcomes after stroke were also collected prospectively by telephone or face-to-face interview. Independent reviewers rated neuroimaging characteristics with the acceptable inter-rater reliability including relevant artery stenosis (0 - 50% stenosis of the adjacent arteries on MR angiography), branched atheromatous lesion (≥4 consecutive axial cuts or extension from the basal surface of brainstem), white matter hyperintensities, old lacunar infarction and cerebral microbleeds. Results: END occurred in 79 (13.5%) cases, including 6 recurrences (8%), 66 progressions (84%) and 7 other causes (9%). Symptomatic hemorrhagic transformation was not documented. NIHSS score was increased when END occurred by 2.3 ± 1.4 points. END patients had higher frequency of having mRS score 3 - 6 at 3 months than those without END (49% vs. 23%). In the multivariable analyses, relevant artery stenosis (adjusted OR 1.91, 95% CI 1.13 - 3.21) and branch atheromatous lesion (2.98; 1.80 - 4.93) had significantly higher odds of having END. However, such association was not detected in the stigmas of small vessel diseases. Conclusions: Relevant artery stenosis and branch atheromatous lesions were significantly associated with the occurrence of END in SSSIs, which suggest a potential contribution of the localized atherosclerotic process to the END in SSSIs. Our results suggest that precautionary measures might be utilized for SSSI patients with higher atherosclerotic burdens.

Stroke : Highlights of Selected Articles

<i>Stroke</i> : Highlights of Selected Articles

The Impact of Prior Antithrombotic Status on Cerebral Infarction in Patients with Atrial Fibrillation

Anticoagulation effectively prevents cardioembolic stroke in atrial fibrillation (AF) patients, whereas it is less effective than antiplatelet therapy (AT) in noncardioembolic stroke prevention. We hypothesized that the ischemic lesion pattern and vascular patency would differ according to the antithrombotic treatment status in AF patients. The medical records of 1078 acute ischemic stroke patients with AF were retrospectively reviewed. Patients were classified according to medication at stroke onset: (1) optimal anticoagulation (OAC; international normalized ratio [INR] 1.7-3.0; n = 36); (2) suboptimal anticoagulation (SOAC; INR ≤1.7; n = 134); (3) AT (n = 285); and (4) control (no antithrombotic medication; n = 623). Imaging and clinical variables of each group were compared with that of controls. Small cortical or single subcortical infarctions were more common in the OAC group than in controls (6% vs. 1% and 22% vs. 8%, respectively; standardized residual, 2.4 and 2.8). Multicirculatory infarctions were less common in the OAC group than in controls (0% vs. 11%; standardized residual, -2.0). Obstruction of the corresponding artery was less common in the OAC group than in controls (26.5% vs. 46.5%, P = .02). Initial neurologic severity was lower in the OAC and AT groups than in controls (P = .01 and .03, respectively). OAC and AT were independently associated with favorable functional outcome at 3-months (P = .015 and <.001, respectively). Ischemic stroke can occur during OAC in AF patients. Small cortical or single subcortical lesions were more common than typical cardioembolic lesion patterns. OAC and AT were protective against severe neurologic deficit and independently associated with favorable outcome, but SOAC was not.

Branching Patterns Determine the Size of Single Subcortical Infarctions

The size variation of single subcortical infarcts (SSIs) may be because of differences in stroke mechanisms or branching patterns of perforators. We aim to investigate this issue using high-resolution MRI. Patients with high-resolution MRI-identified SSI without significant (≥50%) middle cerebral artery stenosis were enrolled. Perforator stems were defined as perforators originating from the middle cerebral artery and perforator branches as linear structures inside the infarcted area, traceable from >2 adjacent slices. The branching index was calculated as the number of perforator branches divided by the number of perforator stems. Clinical and imaging characteristics were compared between large (≥20 mm in diameter) and small SSI groups. Forty-one patients (10 large and 31 small SSIs) were enrolled. Larger SSIs were more closely associated with diabetes mellitus and severe neurological dysfunction but not with the presence of middle cerebral artery plaque. Although there was no difference in the number of perforator stems, the number of perforator branches (4.8±2.2 versus 2.3±1.4; P=0.005) and branching index (2.9±1.0 versus 1.2±0.8; P<0.001) was higher in the large SSI group. SSI diameter showed a significant correlation with the number of perforator branches (r=0.630; P<0.001) and branching index (r=0.750; P<0.001). SSI diameter seems to be associated with anatomic branching variation rather than the mechanism of stroke. Definition of small vessel disease with lesion diameter criteria may not be appropriate.

Ischemic stroke subtype classification: an asian viewpoint.

Proper classification of the causative mechanism of stroke is important for optimizing stroke treatment and assessing prognosis. The primary etiology of stroke differs according to race and ethnicity: emboli originating from the heart or extracranial large arteries are common in Western populations, whereas small-vessel occlusion or intracranial atherosclerosis is more prevalent in Asians. Intracranial atherosclerosis frequently leads to stroke by branch-artery occlusion, and the degree of stenosis in these cases is often <50%. Mild intracranial atherosclerotic stenosis may cause distal embolization, if the atherosclerotic plaque is sufficiently vulnerable. Moreover, high-resolution magnetic resonance imaging studies have identified small plaques causing infarction, even in patients with normal-appearing vascular findings. Such cases, which are prevalent in Asia, could not be classified as large-artery atherosclerosis by previous classification systems. Additionally, single subcortical infarctions, which are usually attributed to lipohyalinotic small-vessel disease, can have other causes, including microatheroma of perforators and atherothrombotic lesions at the parental artery. Single subcortical infarctions associated with parental artery disease or those bordering on the main vessel more often have atherosclerotic characteristics than do those associated with lipohyalinosis of the penetrating artery. In countries where intracranial atherosclerosis is common, such atherosclerotic single subcortical infarctions are predicted to be prevalent. These cases, however, could not be appropriately classified in previous systems. Further effort should be devoted to formulate ischemic stroke classification systems that adequately incorporate results of recent studies and reflect the underling pathologic mechanisms, especially in patients with single subcortical infarction and intracranial atherosclerosis.

Research on intracranial atherosclerosis from the East and west: why are the results different?

Intracranial atherosclerosis (ICAS) is a major cause of stroke worldwide and is more common in Asians than Caucasians. The study results from the East and West are generally similar, but notable differences exist. For example, studies from the East have reported that ICAS is associated with young age, whereas ICAS seems to be associated with old age in the West. Studies from the East have strongly suggested that mild ICAS associated with branch occlusion is one of the main causes of single subcortical infarction, whereas this aspect has not been considered in stroke classification systems developed in the West. While clopidogrel is commonly used in patients with large artery disease in the West, cilostazol has been more extensively studied and commonly used in ICAS patients in the East. A randomized controlled study from the West reported negative results regarding the efficacy of stenting in ICAS patients due largely to a relatively high rate of periprocedural adverse events, whereas research papers from the East have reported a relatively lower rate of complications. Studies to narrow these East-West gaps should be performed, including risk factor studies using homogenous ethnic populations, studies investigating appropriate classification systems, drug trials in different ethnic populations, and rigorous high standard randomized controlled studies on the efficacy of stenting in Eastern populations.

Single Subcortical Infarction and Atherosclerotic Plaques in the Middle Cerebral Artery

Single subcortical infarction (SSI) may be classified as proximal SSI (pSSI) or distal SSI (dSSI) according to its extension to the middle cerebral artery (MCA). We investigated the differences between pSSI and dSSI in terms of their clinical features, lesion size, and the frequency of MCA plaques detected by high-resolution MRI. Thirty-nine patients with SSI (20 pSSI and 19 dSSI) were prospectively enrolled who did not show relevant MCA disease on MR angiography. Lesion size, neurological status (initial National Institutes of Health Stroke Scale score and modified Rankin Scale at 3 months), and the presence and location (superior versus inferior) of high-resolution MRI-identified plaques were evaluated. The frequencies of MCA plaques did not differ between patients with pSSI and those with dSSI (8 [40%] versus 12 [63.2%]; P=0.205); however, superiorly located plaques were significantly more common in patients with pSSI than in those with dSSI (6 [75%] versus 2 [16.7%]; P=0.019). Initial lesion volumes were larger (1.96±1.18 versus 1.11±1.11 mm(3); P=0.025), National Institutes of Health Stroke Scale scores were higher (5 [3-6.75] versus 3 [1-3] points; P=0.017), and microbleeds were fewer (1 [5%] versus 10 [52.6%]; P=0.001) in patients with pSSI than in those with dSSI. Three-month modified Rankin Scale scores were higher in patients with superior plaques than in those with inferior plaques. Compared with dSSI, pSSI is closely associated with large lesions, severe clinical symptoms, and superiorly located MCA plaques, suggesting that the location, rather than simple presence of plaques, determines the SSI location.