Detailed phenotyping of posterior vs. anterior circulation ischemic stroke: a multi-center MRI study

OBJECTIVE

Posterior circulation ischemic stroke (PCiS) constitutes 20-30% of ischemic stroke cases. Detailed information about differences between PCiS and anterior circulation ischemic stroke (ACiS) remains scarce. Such information might guide clinical decision making and prevention strategies. We studied risk factors and ischemic stroke subtypes in PCiS vs. ACiS and lesion location on magnetic resonance imaging (MRI) in PCiS.

METHODS

Out of 3,301 MRIs from 12 sites in the National Institute of Neurological Disorders and Stroke (NINDS) Stroke Genetics Network (SiGN), we included 2,381 cases with acute DWI lesions. The definition of ACiS or PCiS was based on lesion location. We compared the groups using Chi-squared and logistic regression.

RESULTS

PCiS occurred in 718 (30%) patients and ACiS in 1663 (70%). Diabetes and male sex were more common in PCiS vs. ACiS (diabetes 27% vs. 23%, p < 0.05; male sex 68% vs. 58%, p < 0.001). Both were independently associated with PCiS (diabetes, OR = 1.29; 95% CI 1.04-1.61; male sex, OR = 1.46; 95% CI 1.21-1.78). ACiS more commonly had large artery atherosclerosis (25% vs. 20%, p < 0.01) and cardioembolic mechanisms (17% vs. 11%, p < 0.001) compared to PCiS. Small artery occlusion was more common in PCiS vs. ACiS (20% vs. 14%, p < 0.001). Small artery occlusion accounted for 47% of solitary brainstem infarctions.

CONCLUSION

Ischemic stroke subtypes differ between the two phenotypes. Diabetes and male sex have a stronger association with PCiS than ACiS. Definitive MRI-based PCiS diagnosis aids etiological investigation and contributes additional insights into specific risk factors and mechanisms of injury in PCiS.

Distribution of Cardioembolic Stroke: A Cohort Study

BACKGROUND

A cardiac origin in ischemic stroke is more frequent than previously assumed, but it is not clear which patients benefit from cardiac work-up if obvious cardiac pathology is absent. We hypothesized that thromboembolic stroke with a cardiac source occurs more frequently in the posterior circulation compared with thromboembolic stroke of another etiology.

METHODS

We performed a multicenter observational study in 3,311 consecutive patients with ischemic stroke who were enrolled in an ongoing prospective stroke registry of 8 University hospitals between September 2009 and November 2014 in The Netherlands. In this initiative, the so-called Parelsnoer Institute-Cerebrovascular Accident Study Group, clinical data, imaging, and biomaterials of patients with stroke are prospectively and uniformly collected. We compared the proportions of posterior stroke location in patients with a cardiac stroke source with those with another stroke etiology and calculated risk ratios (RR) with corresponding 95% CI with Poisson regression analyses. To assess which patient or disease characteristics were most strongly associated with a cardiac etiology in patients with ischemic stroke, we performed a stepwise backward regression analysis.

RESULTS

For the primary aim, 1,428 patients were eligible for analyses. The proportion of patients with a posterior stroke location among patients with a cardiac origin of their stroke (28%) did not differ statistically significant to those with another origin (25%), age and sex adjusted RR 1.16; 95% CI 0.96-1.41. For the secondary aim, 1,955 patients were eligible for analyses. No recent history of smoking, no hyperlipidemia, coronary artery disease, a higher age, and a higher National Institutes of Health Stroke Scale (NIHSS) score were associated with a cardiac etiology of ischemic stroke.

CONCLUSIONS

We could not confirm our hypothesis that thromboembolic stroke localized in the posterior circulation is associated with a cardioembolic source of ischemic stroke, and therefore posterior stroke localization on itself does not necessitate additional cardiac examination. The lack of determinants of atherosclerosis, for example, no recent history of smoking and no hyperlipidemia, coronary artery disease, a higher age, and a higher NIHSS score are stronger risk factors for a cardiac source of ischemic stroke.

Bilateral temporal lobe disease: looking beyond herpes encephalitis

Abstract

The temporal lobes have unique architecture, and functionality that makes them vulnerable to certain disease processes. Patients presenting with bilateral temporal lobe disease are often confused and have altered consciousness, and are therefore unable to provide cogent histories. For these reasons, imaging plays an important role in their workup and management. Disease entities causing bilateral temporal lobe involvement can be infectious, metabolic, neoplastic, and degenerative aetiologies, as well as trauma and cerebrovascular events. We will first describe the structural and functional anatomy of the temporal lobes and explain the mechanisms that underlie bilateral temporal lobe disease, and then show and discuss the different disease entities and differential diagnosis.

Teaching points

• Bilateral temporal lobe disease is a unique pattern with specific differential diagnosis.

• Patients presenting with bilateral temporal lobe disease are often confused.

• Radiologists should be familar with the variety of disease processes that cause bitemporal disease.