FIG 1. Patient 19 with chronic atrial fibrillation on warfarin (INR = 2.5) and sudden onset of left hemiplegia and mental confusion (NIHSS score=19).

Subtle early signs of cerebral ischemia were seen in the right basal ganglia region on the pretreatment plain CT (A). The subsequent DSA with selective right common carotid injection in the AP view (B) showed a thromboembolic right siphon occlusion in the absence of collateral circulation (not shown). Clot aspiration, PTA, and local administration of as much as 500,000 IU of urokinase resulted in reopening of the siphon with good filling of the proximal M1 tract, anterior cerebral artery, posterior cerebral artery, and ophthalmic artery, the latter originating directly from the siphon through the posterior communicating artery (C). The late arterial phase of selective right internal carotid injection (LL view) showed retrograde filling of distal MCA branches through leptomeningeal anastomosis as well as a deep avascular area (D). The immediate postprocedural CT scan showed marked (>90 HU) enhancement of right basal ganglia with mass effect consistent with contrast extravasation (E). After a transitory clinical improvement (>4 points in the NIHSS score) the patient worsened dramatically 6 hours later and on the control CT scan a devastating cerebral bleeding with intraventricular inundation was observed (F). The patient died the following day.