VASCULAR DISTRIBUTION OF PARADOXICAL EMBOLI BY TRANSCRANIAL DOPPLER

Background and purpose. Paradoxical embolism through a patent foramen ovale is a contributory mechanism to stroke and may be diagnosed by co ntrast echocardiography. The intracranial distribution of these emboli has not been previously reported. Methods. We used transcranial Doppl er combined with agitated saline contrast injection to determine wheth er there was a preferential distribution of the contrast into the ante rior or posterior intracranial circulation of patients with an acute s troke or transient ischemic attack. Results. Forty-nine patients were studied-27 men and 22 women, with a mean age of 62.7 +/- 13.3 years (r ange, 29 to 85 years). Microcavitations were detected in the proximal right middle cerebral artery in 12 of 49 patients (24%). A patent fora men ovale was confirmed in all cases by simultaneous transesophageal e chocardiography. Of the 12 patients, microcavitations were also detect ed in the proximal basilar artery in nine (75%). Conclusions. While pa radoxical embolism appears to occur more frequently in the anterior ci rculation, the high rate of detection of microcavitations in the basil ar artery suggests that paradoxical embolism to the posterior intracra nial circulation may be more frequent than generally believed.