Right-to-left shunts and micro-embolization in migraineKoppen, Hillea,b; Palm-Meinders, Inge H.c; Ferrari, Michel D.bCurrent Opinion in Neurology: June 2012 - Volume 25 - Issue 3 - p 263–268 doi: 10.1097/WCO.0b013e3283524103 HEADACHE: Edited by Messoud Ashina Abstract Author Information Purpose of review: The present review covers the latest studies on right-to-left shunts (RLSs) in migraine patients and different types of emboli capable of triggering migraine. Recent findings: Although three recent studies found no increased RLS prevalence in migraine with aura patients, there remains ample evidence that the prevalence of RLS is increased in migraine with aura. Introduced emboli in the carotid artery of mice have been shown to cause cortical spreading depression, which has been considered the pathophysiological mechanism of migraine aura. In humans, iatrogenic introduced (micro)-emboli can provoke migraine attacks; available evidence, however, is limited. Summary: RLS and migraine with aura (but not without) are comorbid conditions, but the biological mechanism remains speculative. Specific emboli are probably able (although infrequently) to induce migraine symptoms. There is no convincing evidence that closure of a RLS alters migraine frequency; therefore, diagnosis or treatment of RLS in migraine has no place in daily clinical practice and should only take place in controlled studies. aDepartment of Neurology, Haga Hospital, The Hague bDepartment of Neurology cDepartment of Radiology, Leiden University Medical Center, Leiden, The Netherlands Correspondence to Hille Koppen, Department of Neurology, Haga Hospital, P.O. Box 40551, 2504 LN, The Hague, The Netherlands. Tel: +31 70 2100000; e-mail: firstname.lastname@example.org © 2012 Lippincott Williams & Wilkins, Inc.