A Case of Recurrent Ischemic Stroke due to Paradoxical Embolism through Different Channels Dong-geun Lee, M.D., Seungyoo Kim, M.D., Jae Young An, M.D., Sung Kyung Park, M.D., Si-Ryung Han, M.D., Ph.D. Department of Neurology, St. Vincent's Hospital, The Catholic University of Korea Background In evaluating an ischemic stroke, we should think of other causes, such as cardioembolism, vasculitis or paradoxical embolism, if there were no vascular risk factors or vasculopathy in neuroimaging tests. We report a puzzling case of recurrent ischemic strokes possibly due to paradoxical embolism through different channels. Case and Course A 37 year old female was admitted because of headache, dizziness, nausea and vomiting had started abruptly. She had no vascular risk factors such as, hypertension, diabetes, cigarette smoking, physical inactivity, dyslipidemia and obesity. Neurological examination revealed non-specific except the tendency of swaying to left side during tandem gait. Magnetic resonance image revealed high signal intensity (SI) change on left posterior inferior cerebellar arterial (PICA) territory of cerebellum on T2 weighted image and diffusion weighted images (DWI). Magnetic resonance angiography (MRA) showed no sign of atherosclerosis, dissection, aneurysm, or stenosis. Examinations to rule out cardioembolism such as, electrocardiogram, 24 hour Holter monitoring, trans-thoracic echocardiogram (TTE) resulted in normal. But on transcranial Doppler (TCD) sonography, there were multiple microembolic signals (MES) during agitated saline test. Trans-esophageal echocardiogram (TEE) revealed patent foramen ovale (PFO). We started anticoagulation for secondary prevention. 2 months later, surgical correction of PFO was done. On operation field, 0.5cmX0.5cm sized PFO was observed after right atriotomy, and it was directly closed by 5-0 prolene suture. She discharged without any complication. 11 months later after PFO closure, the patient was admitted again. At that time she complained of dizziness. DWI revealed high SI in the PICA territory of right cerebellum. MRA revealed no arteriopathy again. On TCD, there were multiple MES during valsalva maneuver again, but on TEE, there was no sign of agitated saline leakage through PFO closure site. We thought that there could be another channel of paradoxical embolization. We did computed tomography (CT) on chest, and it revealed an engorged pulmonary vessels at anterior basal segment of right lower lobe, suggestive of pulmonary arterio-venous malformation (AVM) draining into the right lower pulmonary vein. Pulmonary angiography confirmed of AVM and embolization with coil was done in endovascular manner. We observed the patient for 18 months, and no cerebrovascular accident was recurred, ever after. Discussion Ischemic stroke due to paradoxical embolism through right to left shunt is sometimes puzzling and hard to be diagnosed if not suspected. Although the etiology was confirmed as a paradoxical embolism, the possibility of extracardiac shunt should be considered, for many of ischemic stroke seems to stem from extracardiac shunt, especially pulmonary AVM. And tools or methods to detect extracardiac shunt easily, should be developed. & First event 4 6 3 1 5 2 1&2. DWI and ADC map revealed acute infarction in left PICA territory. 3. MRA revealed no ateriopathy. 4. Contrast enhanced TCD of temporal window revealed microembolic signals during resting state. 5. There are echogenic jets(red arrow) from right atrium to left atrium through PFO(white arrow) in contrast enhanced TEE with agitated saline. 6. There is patent foramen ovale(green arrow) observed after right atriotomy. It was closed with 5-0 prolene suture meticulously. 4. Contrast enhanced TCD of temporal window revealed microembolic signals during resting state. Second event 4 1 3 6 8 5 7 2 9 1&2. DWI and ADC map revealed acute infarction in right cerebellum. 3. MRA revealed no ateriopathy again. 4. Contrast enhanced TCD of temporal window revealed microembolic signals during resting state. But on TEE there was no leak through PFO closure site(not shown) 5. Possible pulmonary AVM??? 6&7. On enhanced chest CT, there were engorged pulmonary vessels at anterior basal segment of RLL. 8&9. There found a nidus on pulmonary angiography and embolization with coil was done in endovascular manner