American Heart Association

Yearly Archives: 2016

Inverse Relationship Between Leukocyte Count and ICH Hematoma Expansion

Alexander E. Merkler, MD 
Intracerebral hemorrhage (ICH) is a catastrophic type of stroke with a one-month mortality of 40%. Although initial ICH volume is the strongest predictor of mortality, hematoma expansion is a potentially modifiable risk factor that correlates well with both functional outcome and death and occurs in up to 40% of patients with ICH. Research has therefore focused on 1) identification of factors that predict hematoma expansion and 2) methods to reduce hematoma expansion. 

The relationship between neuroinflammation, WBC count, and ICH pathophysiology is complex with prior studies suggesting that a higher WBC count predicts worse outcome. On the other hand, acute leukocytosis is associated with coagulation and consequently may lead to an arrest hematoma expansion in ICH. In this study, Dr. Morotti et al. evaluate the relationship between admission leukocytosis and hematoma expansion in patients with ICH. Hematoma expansion was defined as an increase in ICH volume of >30% or >6mL. WBC count was analyzed in quartiles.  
The authors retrospectively evaluated 1302 prospectively collected patients with non-traumatic ICH. Of these patients, 15.9% experienced a hematoma expansion. The median WBC count on admission was 9200 cells/uL. Overall, after adjustment for demographics and other risk factors for hematoma expansion, higher admission WBC was independently associated with a reduced risk of hematoma expansion (OR for 1000 cells increase 0.91, 95% CI 0.86-0.96). In secondary analyses, the authors evaluated the effect of WBC subtypes on hematoma expansion; higher admission neutrophil count was associated with a lower risk of hematoma expansion (OR for 1000 cells increase 0.90, 95% CI 0.85-0.96) whereas higher admission monocyte count was associated with hematoma expansion (OR for 1000 cells increase, 2.71, 95% CI 1.08-6.83). Lymphocyte count was not associated with hematoma expansion.
Despite certain limitations such as lack of information regarding baseline infectious/inflammatory conditions that may have affected admission WBC counts, the study is certainly suggestive that acute inflammation plays a role in modulating the coagulation cascade following ICH. Perhaps identification of methods to acutely alter neuroinflammation may prove to be a salient method to halt hematoma expansion.
By |May 18th, 2016|clinical|Comments Off on Inverse Relationship Between Leukocyte Count and ICH Hematoma Expansion

Declining Rate of IV Heparin Use in Acute Ischemic Stroke in Korea

Jay Shah, MD

Chung J-W, Kim BJ, Han M-K, Ko Y, Lee S, Kang K, et al. Impact of Guidelines on Clinical Practice: Intravenous Heparin Use for Acute Ischemic Stroke. Stroke. 2016

IV heparin has been available since the 1940’s and its role in ischemic stroke has been constantly debated. IV heparin has a clear indication in cardiac ischemia and many presume its efficacy should translate in acute ischemic stroke as well. However, numerous studies have failed to show benefit and American Stroke Association does not recommend anticoagulation acutely. Because heparin has been available for numerous years, there is little information on contemporary use and this study evaluated recent IV heparin trends across 12 hospitals in Korea in a 5 year span from 2008-2013.

Data was obtained from an acute stroke registry that included consecutive stroke patients. Information regarding stroke characteristics, recanalization treatment and antithrombotic treatment during hospitalization and post-discharge were collected. In total, 23,425 patients were included in the study. In the study period, the rate of recanalization treatment increased. Use of IV heparin decreased consecutively during the study period with use of 4.3% in 2013 compared to 9.7% initially. In the small proportion of patients that were treated with IV heparin, atrial fibrillation was associated with more frequent use.

This study shows declining rates of IV heparin use in acute ischemic stroke. This coincides with a 2009 publication of a Korean stroke clinical practice guideline and supports adherence to guidelines by neurologist. Interestingly, atrial fibrillation was associated with use of IV heparin. Typically, cardioembolic strokes are generally larger and acute anticoagulation is not pursued due to hemorrhage risk. Furthermore, subsequent short-term stroke risk following a cardioembolic stroke is relatively lower (unlike large vessel disease) and delaying anticoagulation until hemorrhage risk is lower has become the standard practice. Use of IV heparin is sometimes reserved for patients with critical carotid stenosis awaiting carotid endarterectomy but such decisions are made on case-by-case basis. This study further affirms that clinical guideline recommendations impact clinical decision making and have the ability to impact outcomes as well.

By |May 10th, 2016|treatment|Comments Off on Declining Rate of IV Heparin Use in Acute Ischemic Stroke in Korea

Limited Meta-analysis Suggests Patients with Asymptomatic Carotid Occlusion are at Low Risk of Ipsilateral Stroke, High Risk of Non-stroke Mortality

Danny R. Rose, Jr., MD

Hackam DG. Prognosis of Asymptomatic Carotid Artery Occlusion: Systematic Review and Meta-Analysis. Stroke. 2016

Although carotid artery occlusion is estimated to account for 10-15% of all ischemic strokes and transient ischemic attacks, there is little consensus regarding the long-term prognosis of asymptomatic carotid artery occlusion (ACAO), which is most often found incidentally during workup for cerebrovascular disease. Hackam sought to shed light on this issue by conducting a systematic review of studies that enrolled patients with ACAO that collected follow-up information on the occurrence of ipsilateral ischemic stroke as an outcome measure. 

A total of 13 studies were included in the meta-analysis. The studies enrolled 4406 patients, 718 of whom had ACAO (16%). The median age of patients with ACAO was 67 and 23% were female.  All but two studies used ultrasound to define ACAO diagnostically; however the use of angiography was high overall (66% of subjects). Median follow-up was 2.80 years, with an annual ipsilateral stroke rate of 1.3% (95% CI 0.4-2.1%). Two-year and 5-year rates of stroke were 2.5% and 6.3%, respectively. There was substantial heterogeneity in the base estimate (I2=53%). Annual total stroke was 2.0% (95% CI 0.9-3%; I2=40%). 

Eleven studies reported on ipsilateral TIA, with an annual rate of 1% (95% CI 0.3-1.8% I2=40%) and an annual total TIA rate of 3.0% (95% CI 1.9-4.1% I2=0).  Seven studies reported mortality, with an annual rate of death of 7.7% with marked heterogeneity (95% CI 4.3-11.2% I2=83%). Six studies reported stroke-related death, with an annual rate of 1.1% (95% CI 0.07-2.1% I2=63%). Cardiac death was more frequent at 3.3% per year (95% CI 1.2-5.4% I2=83%). In the prescribed subgroup analysis, studies published on or after the year 2000 had a statistically significantly lower aggregate ipsilateral stroke rate than studies published before 2000 (0.9% to 1.5%, p=0.003). Adjusting for publication bias suggested a revised ipsilateral stroke rate of 0.3% per year (95% CI -0.4 to 1.1%).

Although the study was limited by significant heterogeneity, it suggests that the risk from ACAO is low. With subgroup analysis of studies published after the advent of contemporary medical management of vascular disease and trim-and-fill analysis suggesting a lack of studies published to the left of the mean, the rate is likely lower than the 1.3% per year grand mean that was reported. However, the annual risk of death was quite high (7.7%), likely attributable to ACAO being a surrogate marker of systemic atherosclerosis, possibly carrying a higher risk of cardiac death. 

Further study of this population is warranted. Potential avenues for future study would include a prospective cohort of patients with medically managed carotid stenosis and occlusion with matched controls, following a variety of vascular outcomes. Perfusion or more in-depth angiographic imaging to identify a potential subset of patients at higher risk of stroke could also be of use.  
By |May 9th, 2016|prevention|Comments Off on Limited Meta-analysis Suggests Patients with Asymptomatic Carotid Occlusion are at Low Risk of Ipsilateral Stroke, High Risk of Non-stroke Mortality

Heart Rate Variability and Incident Stroke Risk in the Atherosclerosis Risk in Communities Study

Neal S. Parikh, MD
In this issue of Stroke, Amber Fyfe-Johnson and colleagues describe their investigation of the association between heart rate variability (HRV) and incident stroke risk in the Atherosclerosis Risk in Communities (ARIC) Study cohort.

They argue that autonomic nervous system (ANS) dysfunction, as reflected by HRV, may be associated with cardiovascular mortality, coronary heart disease, and mortality in stroke survivors. ANS dysfunction may be associated with dysregulated cerebrovascular autoregulation and blood pressure.

ARIC participants were assessed by EKG for HRV by four measures at visit 1 (1987-1989) and followed through December 31, 2011 for incident stroke by telephone ascertainment, hospital discharge diagnosis review, and state death registry review. Covariates, collected at the index visit and again at visit 4 (1996-1998), included: age, sex, race, smoking/alcohol use, physical activity, body mass index, blood pressure, blood lipids, and diabetes. Patients taking medications that modify HRV (beta-blockers, anti-arrythmics, calcium channel blockers, digoxin) and those with prevalent stroke, coronary disease, or heart failure were excluded.  

Cox proportional hazards models were used to calculate hazard ratios for the relationship between each quintile of HRV measures and stroke.

Of 12,550 ARIC participants, 816 (6.5%) had stroke. Crude cumulative stroke incidence was higher in patients with the lowest HRV quintile (compared to the highest quintile). However, after adjustment for covariates, associations between HRV and stroke risk were attenuated and did not meet statistical significance. In analyses restricted to participants with diabetes, stroke risk was higher in the lowest HRV quintile, but this association was only statistically significant when testing one of four HRV measures (HR 2.0, 95% confidence interval, 1.1-4.0).

The authors conclude that there may be an association between low HRV and incident stroke in populations already at risk – patients with diabetes. Whether this association would withstand adjustment for an expanded list of cardiovascular risk factors in a modern cohort is unclear. However, the importance of identifying simple indicators of stroke risk such as HRV cannot be overstated. 
By |May 6th, 2016|epidemiology and genetics|Comments Off on Heart Rate Variability and Incident Stroke Risk in the Atherosclerosis Risk in Communities Study

Hematoma Shape, but not Density, is Predictive of Clinical Outcomes in ICH from the INTERACT2 Study

Peggy Nguyen, MD

Delcourt C, Zhang S, Arima H, Sato S, Al-Shahi Salman R, Wang X, et al. Significance of Hematoma Shape and Density in Intracerebral Hemorrhage: The Intensive Blood Pressure Reduction in Acute Intracerebral Hemorrhage Trial Study. Stroke. 2016

In patients with intracerebral hemorrhage (ICH), parameters such as hematoma volume has been shown to be predictive of hematoma growth and poor clinical outcomes; other characteristics, such as shape and density have been shown to be associated with growth, but evidence demonstrating its predictive value for clinical outcomes has been limited. Here, the authors used data from the INTERACT2 study and evaluated the association of hematoma shape (irregularity) and density (heterogeneity) on 90-day death or disability.

2066 subjects were included for analysis, with 946 subjects having irregular hematomas and 781 subjects having heterogenous hematomas. Of note, there were significant differences between patients with irregular versus regular hematomas, including older age, more severe neurological status, and lobar hemorrhages in the former group, among others. Similarly, patients with heterogenous hematomas, compared to those with homogenous hematomas, were more likely to have lobar hematomas and less likely to have intraventricular extension. Larger hematomas were more likely to be irregular and heterogenous, and this is likely reflected in the differences between each group and their comparators. In addition, the decision to withdraw treatment was more likely to be made among patients with irregular hematomas and among patients with heterogenous hematomas, when compared to their counterparts.

Nevertheless, when controlled for factors such as age, systolic blood pressure, NIHSS, prior use of antithrombotics, location and volume of baseline hematoma, IVH, and decision to withdraw active treatment, irregular hematomas were found to be independently associated with the primary outcome of risk of death or major disability at 90-days (OR 1.60) and major disability at 90 days (OR 1.60) although not with death alone. Heterogenous density did not predict the primary outcome, nor individually, the outcome of death nor disability.

This study is significant in providing some evidence for imaging markers which may be predictive of clinical outcomes in the emergent period, allowing clinicians to adjust decision making and provide better informed counseling to patients and their families.   

By |May 4th, 2016|hemorrhage|Comments Off on Hematoma Shape, but not Density, is Predictive of Clinical Outcomes in ICH from the INTERACT2 Study

Genetic Factors that Impact White Matter Hyperintensities Increase Risk of Lacunar Stroke

Jay Shah, MD

Traylor M, Rutten-Jacobs LCA,Thijs V, Holliday EG, Levi C, Bevan S, et al. Genetic Associations With White Matter Hyperintensities Confer Risk of Lacunar Stroke. Stroke. 2016

Small vessel disease (SVD) can lead to various pathologies including lacunar infarcts, hemorrhage and microbleeds but the underlying pathophysiological mechanism remains unknown. White matter hyperintensities (WMH) are increased in lacunar stroke suggesting a shared pathological mechanism. Furthermore, WMH and lacunar infarcts co-exist in patients with inherited forms of SVD such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Genome-wide association studies (GWAS) have identified multiple genetic variants associated with WMH. In this study, the authors evaluated the impact of common genetic variants associated with WMH on the risk of lacunar stroke in patients with lacunar strokes and controls.
The authors used a genetic risk score approach to determine if SNPs associated with WMH were associated with lacunar strokes along with cardioembolic and large vessel infarcts. Each subgroup included approximately 1300 patients and 9000 controls. Secondly, lacunar strokes were separated into WMH (n = 568) and without WMH (n=787) to test for association. WMH genetic risk score was associated with lacunar stroke in patients regardless of WMH status but not with cardioembolic or large vessel strokes. However, none of the WMH-associated SNPs met significance for association with lacunar stroke.

This study supports the known belief that features of cerebral SVD share pathophysiology. Interestingly, the risk of lacunar stroke remained in patients without significant WMH. This could potentially be to the effect of “time”, in that patients without WMH could possibly be younger and have not had accumulated SVD damage. Another possibility is that patients without WMH have an unknown protective mechanism that protects against WMH but not lacunar stroke. The latter would be interesting in that it would suggest differing pathological mechanism. The study had large number of patients and controls but a potential confounding variable is that control patients did not have MRI images raising the possibility that controls had lacunar strokes and/or WMH as such pathology can potentially be clinically “silent”. Nonetheless, this study highlights a shared pathophysiological process that underlies various manifestations of CVD. 

By |May 3rd, 2016|diagnosis and imaging|Comments Off on Genetic Factors that Impact White Matter Hyperintensities Increase Risk of Lacunar Stroke

Is Anticoagulation Safe in ENT/CNS Infection Associated Central Venous Thrombosis?

Alexander E. Merkler, MD

Head and Neck Infections are not uncommonly associated with central venous thrombosis (CVT). Previous studies claimed that in as many as 60% of cases of CVT, there is an associated ENT or CNS infection, although more recent publications state that the rates of associated infections are much less, likely due to improved antibiotic treatment. Despite the presence of intracerebral hemorrhage, CVT is typically treated with anticoagulation. On the other hand, there is insufficient evidence to support treatment with anticoagulation for CVT due to or associated with a concurrent head or neck infection.

In the current study, Dr. Zuurbier et al. assess the differences between CVT patients with and without concurrent head or neck infection. In addition, the authors assess the use and effect of anticoagulation in patients with CVT and concurrent infection. This study data was collected as part of the prospectively gathered International Study on Cerebral Venous and Dural Venous Thrombosis (ISCVT) which included 624 adults with CVT.

Out of the 624 patients with CVT, 77 patients had an infection. Twenty had an infection outside of the head or neck and were excluded. Thus, out of the 600 patients that remained, 57 patients had a head or neck infection, out of which an ENT infection (mastoiditis) was the most common. Thirteen (22.8%) had a CNS infection. As compared to patients without an infection, cavernous sinus thrombosis was more common in patients with an infection (7.7 versus 0.7%). In addition, an ICH at baseline was less common in patients with an infection (21.1 versus 41.6%). The proportion of patients who received therapeutic anticoagulation was the same in patients with or without an infection (82.% versus 83.7%). Of the patients with an infection, there were no significant baseline differences between those who received anticoagulation and those who did not.

Neurological outcomes (as defined by mRS upon last follow-up) were similar between patients with or without infections; 15.8 versus 13.7% of patients were dead or dependent (mRS>2) at last follow-up. In addition, mortality was similar between patients with and without infection (5.3% versus 3.3%). A new ICH was more common in patients with an infection than without an associated infection (12.3 versus 5.3%) and although not statistically significant due to low numbers of patients, clinical worsening was more frequent in patients with an infection who were treated with anticoagulation (31.9 versus 10%). On the other hand, despite clinical worsening, clinical outcomes at last follow-up and mortality were very similar in patients with an infection treated or not treated with anticoagulation.

One of the most surprising findings of this study was the fact that clinicians were not deterred in prescribing full dose anticoagulation in patients with active ENT/CNS infection. Although overall mortality and neurological outcomes were similar in patients with CVT and concurrent infections treated or not treated with anticoagulation, only 10 patients with CVT and concurrent infection were not treated with anticoagulation and therefore it is hard to attest to the efficacy/safety of anticoagulation in this particularly challenging subgroup of patients.
By |April 29th, 2016|treatment|Comments Off on Is Anticoagulation Safe in ENT/CNS Infection Associated Central Venous Thrombosis?

What Makes a Lacune?

Peggy Nguyen, MD

The lacune, often used interchangeably with the definition of a stroke of small vessel atherosclerotic etiology, is traditionally based on a size definition of no greater than 15 mm. It is a classic feature of cerebral small vessel disease. However, despite its prolific use in the stroke literature, the exact characteristics and morphological features of a lacune are not well defined. Here, the authors analyzed the shape of incident lacunes in CADASIL, a genetically inherited small vessel arteriopathy, to better define the lacune’s morphological features.

Fifty-seven CADASIL patients with incident lacunes were included in the study, encompassing 88 incident lacunes, only 18 of which were associated with symptoms. The most common locations for lacunes were in the centrum semiovale (n=30) and the basal ganglia (n=27). In spectral shape analysis, elongation and planarity were found to be the primary determinants of lacune shape and tended to align along perforating arteries. Although 15 mm is traditionally used as the upper size limit of a lacune, about 10% of lacunes, particularly when evaluated in planes other than axial, exceeded this size, whereas only 1 lacune was larger than 15 mm in the axial plane.

Not all lacunes are created the same, but there are certainly similarities, and this may have to do with the mechanisms by which they develop. The findings in this study confirm some generalizations of lacunes, such as the common locations, but also refutes some others, for instance, the size of lacunes, particularly when viewed in non-axial planes. These findings are also suggestive of a mechanism in which lacunes of chronic small vessel diseases develop secondary to factors related to vascular anatomy, rather than tract degeneration.

By |April 28th, 2016|diagnosis and imaging|Comments Off on What Makes a Lacune?

Get With the Guidelines (GWTG) Participation is Associated with Improved Clinical Outcomes in Medicare Ischemic Stroke Patients

Jay Shah, MD

Quality improvement programs are essential in that they provide vital information on process of care but its impact on clinical outcomes is less known. One such program, Get With the Guidelines-Stroke (GTWG-Stroke), began in 2003 and was developed by the American Heart Association to improve stroke care infrastructure. Hospitals that enter this program have access to wide range of resources and staff support. Prior studies have shown that hospital participation was associated with increased frequency of thrombolysis and interventions to prevent complications. However, the impact on program participation has not been established. Therefore, in this study, the authors queried if clinical outcomes at GWTG-Stroke hospitals differed compared to matched patients at non-GWTG-Stroke hospitals.

This study was conducted in Medicare patients admitted within a 5-year span from 2003 to 2008. Three hundred sixty-six GWTG-Stroke hospitals were identified that had 88,000 ischemic stroke admissions compared to 366 non-GWTG-Stroke hospitals that cared for 85,000 ischemic stroke patients. Within 6 months of program participation, GWTG-Stroke hospitals had greater discharges to home and reduced mortality at 30 days and 1 year. The reduction of mortality at 1 year was sustained at 18 months after program participation.

This study found that hospital implementation in GWTG-Stroke program was associated with improved functional outcomes. It is important to note that improvement in outcomes did occur over time at non-GWTG-Stroke hospitals reflecting the overall increase in awareness, knowledge, and care of ischemic stroke patients. Stroke is a leading cause of morbidity but data on post-stroke modified Rankin scale was not available. While improvement in mortality is certainly noteworthy, improvement in morbidity remains a pertinent clinical question. It is possible that a hospital decision to participate in the program was due to hospital personnel, specifically availability of stroke-trained neurologist and nurses. Therefore, the improvement in outcomes could potentially be due to greater stroke expertise at the specific hospital rather than GWTG participation. Nonetheless, ischemic stroke is a complex disease with multiple variables and outcomes have important implications on quality of life and any method that can potentially improve outcomes should be undertaken.
By |April 27th, 2016|clinical|1 Comment

Early Appearance of Spot Sign on CT Perfusion Associated with Hematoma Expansion and Poor Outcome in Small Retrospective Study

Intracerebral hemorrhage (ICH) causes a significant amount of stroke-related morbidity and mortality. Of the various prognostic factors in ICH, hematoma expansion (HE) is one of the few potentially modifiable ones and as such has been a topic of increasing research.
Unfortunately, large-scale randomized controlled trials aimed at preventing hematoma expansion have not shown robust results, possibly owing to the limited ability of clinicians to predict which patients are at greatest risk. The “spot sign,” a radiographic sign representing the leakage of contrast with a hematoma on CT scan has recently become a topic of extensive study with respect to its ability to predict hematoma expansion. As described previously, a recently published meta-analysis suggested that the sensitivity and positive predictive value of the spot sign was related to the time from ictus to scan acquisition and may not adequately predict HE when it is detected. Additionally, other studies have shown that using CT perfusion (CTP) improves the detection rate of the spot sign. Wang et al. sought to explore the relationship between spot sign characteristics on CTP (including number, timing, and maximum density) to evaluate the relationship between these characteristics and the risk of HE as well as clinical outcome.
The authors’ retrospectively reviewed a total of 83 patients from a prospectively collected database of consecutive patients with supratentorial SICH. Patients receiving surgical evacuation of their hematoma were excluded from the outcome analysis, and additionally were excluded from HE analysis if the intervention took place prior to the 24 h follow-up CT scan. Patients who died prior to the 24 h follow-up CT scan were excluded from the HE analysis.  Patients with secondary causes of ICH were also excluded. A total of eleven patients (6 with positive spot sign) were excluded from the HE analysis, and twelve patients (7 with positive spot sign) were excluded from outcome analysis due to receiving surgical evaluation. Excluded patients had higher SBP and DBP, over a three-fold greater median hematoma volume (52.30 mL vs 15.80 mL, P=0.029) and a nearly two-fold higher median NIHSS (21 vs 11, P=0.004). 

Baseline clinical variables included patient demographics, medical history, medications, onset to imaging time (OIT), baseline National Institute of Health Stroke Scale (NIHSS), and laboratory results. The clinical outcomes assessed were NIHSS at 24 h, in-hospital mortality, and modified Rankin Scale (mRS) including death at 3 months follow-up. Spot sign was assessed with CTP and the timing of occurrence (time from the start of scan to first detection of spot sign), total number of spots, maximum spot attenuation, and axial dimensions were recorded. The median time of onset to CP was 180 (120 to 240) minutes. Hematoma expansion was defined as an absolute ICH growth ≥ 6 mL or relative growth ≥ 33% as recorded on 24 h follow-up CT scan. 

The rate of spot sign was higher in patients with HE than those without (62.5% vs 12.5%, P<0.001). The presence of spot sign was independently associated with HE after correcting for APTT, glucose, NIHSS, baseline hematoma volume, and antiplatelet use. There was a trend for an association between the presence of spot sign and 3-month mortality (32% vs 8%, OR=5.649; 95% CI 0.913-34.954; P=0.063) after multivariate analysis. Spot sign was detected much earlier in patients with HE than those without (18.75 s vs 26.87 s, P=0.007). The timing of spot sign was significantly correlated with both absolute and relative ICH volume growth, and there was no association between the other spot sign characteristics and HE. The authors defined a subset of spot sign patients as having an “early occurring spot sign (EOSS),” defined as detection of the spot sign before 23.13 seconds. EOSS was found to have 0.67 sensitivity and 0.90 specificity for HE. On multivariate analysis, EOSS was an independent predictor of HE (OR=28.835; 95% CI, 6.960-119.458; P<0.001) and 3-month mortality (OR=22.377, 95% CI, 1.773-282.334; P=0.016). EOSS maintained a higher specificity for HE compared to spot sign (91% vs 74%).

In this single-center cohort of SICH patients, spot sign as assessed by CTP was associated with HE. The authors also found that early detection of the spot sign was the most important characteristic with respect to predicting HE and significantly correlated with ICH growth. The primary limitations of the study were related to the retrospective nature of the study, the relatively small sample size, and the use of a single center for recruitment and determining imaging parameters. External validation with a larger sample size and standardized imaging parameters will be necessary. In addition, the high rate of excluded surgical evacuation patients with positive spot sign may have led to an underestimation of the spot sign’s PPV with respect to mortality. It is also important to note that the predictive value and associations with spot sign on CTP in this study should not be applied patients evaluated with single-phase CT angiography. However, replicating this study with multi-phase CTA could be feasible and represents a potential future avenue of research.
By |April 26th, 2016|epidemiology and genetics|Comments Off on Early Appearance of Spot Sign on CT Perfusion Associated with Hematoma Expansion and Poor Outcome in Small Retrospective Study