The authors contributed equally to this work.
Paradoxical embolism as a cause of silent brain infarctions in healthy subjects: the ICONS study (Identification of the Cause of Silent Cerebral Infarction in Healthy Subjects)
Article first published online: 9 SEP 2012
© 2012 The Author(s) European Journal of Neurology © 2012 EFNS
European Journal of Neurology
Volume 20, Issue 2, pages 353–360, February 2013
How to Cite
Kim, S. J., Shin, H. Y., Ha, Y. S., Kim, J. W., Kang, K. W., Na, D. L. and Bang, O. Y. (2013), Paradoxical embolism as a cause of silent brain infarctions in healthy subjects: the ICONS study (Identification of the Cause of Silent Cerebral Infarction in Healthy Subjects). European Journal of Neurology, 20: 353–360. doi: 10.1111/j.1468-1331.2012.03864.x
- Issue published online: 12 JAN 2013
- Article first published online: 9 SEP 2012
- Manuscript Accepted: 6 AUG 2012
- Manuscript Received: 2 MAY 2012
- magnetic resonance imaging;
- paradoxical embolism;
- patent foramen ovale;
- silent brain infarction;
- transcranial Doppler
In healthy elderly people, silent brain infarctions (SBIs) have been recognized as common lesions. In this study, we evaluated the association between SBI located outside the perforating artery territory (PAT) and paradoxical embolism detected by agitated saline transcranial Doppler (TCD) monitoring in healthy subjects.
This was a prospective observational study undertaken by a university health promotion center for healthy subjects and by a university stroke center for acute stroke patients. We defined SBI as evidence on fluid-attenuation inversion recovery (FLAIR) magnetic resonance imaging (MRI) of one or more infarcts, without history of corresponding stroke or transient ischaemic attack. We also evaluated in all subjects the neuroimaging indicator of microangiopathy leukoaraiosis (LA). This study is registered with ClinicalTrials.gov, number NCT01429948.
Amongst 1103 consecutive healthy adults who underwent MRI, 347 (31%) had one or more SBIs located outside the PAT, suggesting embolism. Amongst them, 253 subjects underwent agitated saline TCD monitoring and 128 (51%) had right-to-left shunts (RLS). The prevalence of RLS was similar to cryptogenic embolic stroke (62.0%, P = 0.056), but higher than in patients with other stroke subtypes (36.2%, P = 0.021). Amongst subjects with SBI, absence of LA was the only factor associated with RLS (OR 1.78; 95% CI 1.01–3.14; P = 0.046).
Our results suggest that paradoxical embolism may play an important role in the development of SBI outside the PAT in apparently healthy adults.