a 57-year - old right - handed man with a history of hypertension and current smoking presented 60 minutes after acute onset of left hemiparesis and dysarthria . his national institute of health stroke scale ( nihss ) score was 15 at admission . unenhanced computed tomography ( ct ) of his brain demonstrated a dense right mca sign without intracranial hemorrhage . he was treated with 67 mg of intravenous recombinant tissue plasminogen activator ( rtpa ) . emergent magnetic resonance imaging ( mri ) of the brain was performed using a 1.5-t unit ( signa hdxt ; ge medical systems , milwaukee , wi ) . diffusion - weighted imaging showed an area of restricted diffusion in the right basal ganglia ( fig . the brain mra revealed a complete occlusion at the mid m1 segment of the right mca ( fig . anterior cerebral circulation was supplied from the posterior circulation via the right pcoma and left persistent trigeminal artery . there were no flow - related enhancements of the bilateral icas . despite intravenous infusion of rtpa for one hour , no neurologic improvement was observed . therefore , subsequent endovascular therapy was performed with conscious sedation 140 minutes after symptom onset . a right common carotid artery ( cca ) angiogram demonstrated a chronic occlusion at the origin site of the right ica with a small stump ( fig . a left cca angiogram also showed a chronic occlusion at the origin site of the left ica ( not shown ) . the right vertebral artery ( va ) angiogram confirmed an occlusion at the mid m1 segment of the right mca , which was reconstituted by a patent right pcoma ( fig . we decided to perform a stent - retriever embolectomy for the mca occlusion through the patent pcoma . an 8-f guide catheter was placed in the right va . using a standard technique , a microcatheter with a 0.021-inch diameter was navigated distal to the clot over a 0.014-inch microwire to the right mca through the right pcoma . a 4  20 mm trevo xp provue stent ( stryker , kalamazoo , mi , usa ) was then introduced through the microcatheter and fully deployed across the occluded right mca ( fig . 1e and 1f ) . after the stent was maintained in place for one minute , the fully deployed stent and delivery microcatheter were slowly pulled back together and withdrawn outside the body through the guide catheter . a large red thrombus was retrieved with a trevo stent on a single pass ( fig . 1 g ) . during clot retrieval , continuous manual aspiration with a 50-ml syringe at the guide catheter was performed . a post - thrombectomy control angiogram demonstrated complete revascularization of the occluded mca ( fig . time to revascularization , defined as the time from the femoral access to achievement of revascularization , was 18 minutes . ct of the brain performed 2 days later demonstrated acute infarction in the right basal ganglia without intracranial hemorrhage . at the time of discharge after 10 days after stroke , advances in endovascular technology permit novel approaches for recanalization when direct access to the occluded sites is not possible . this case demonstrates the feasibility and safety of cross - circulation stent retriever embolectomy via a patent pcoma to reach a mca thrombus in the setting of a chronic proximal ica occlusion . access to an intracranial lesion crossing from the proximal major cerebral artery through patent communicating arteries , which is called a trans - circulation technique or cross - circulation technique , was first introduced for aneurysmal coiling . improved design of microwires , microcatheters , stent systems , and guide catheters has facilitated the use of these techniques for endovascular treatment in patients with acute ischemic stroke when direct access to the lesions was impossible . f irst reported this cross - circulation technique for the treatment of acute ischemic stroke in a patient with a mca occlusion via the posterior circulation approach using a patent pcoma with aspiration thrombectomy . later on , liu et al . reported successful anterior - posterior revascularization of a basilar artery occlusion through a patent pcoma with ia thrombolysis and aspiration thrombectomy . has demonstrated that mca occlusions can be recanalized with ia thrombolysis via a patent pcoma , but they achieved complete recanalization in only 25% of eight patients . in the present case report , we present the first case using the cross - circulation technique to perform stent - retriever embolectomy for treatment of the acute mca occlusion in association with chronically occluded cervical ica via the patent pcoma in a patient with acute ischemic stroke . direct access to the occluded mca through the chronically occluded ica might be considered risky and time - consuming . early recanalization of an occluded artery plays a critical role in the prognosis of a patient with acute ischemic stroke . although we did not encounter any technical difficulty or complication when performing embolectomy across the pcoma , the concern regarding advancement of endovascular devices through communicating arteries with a small diameter , such as dissection , rupture or embolic stroke , should be addressed . this risk may be increased in patients with advanced atherosclerotic changes in the proximal carotid and vertebral arteries . the trevo xp provue is constructed of a single closed - cell nitinol hypotube and has no free margins , which might make retrieval of the device atraumatic . these features of the stent might have contributed to the success of revascularization without vascular injury in our case . in conclusion , our case demonstrates the feasibility and safety of stent - based embolectomy by using the cross - circulation technique via a wills circle artery . knowledge of an alternative vascular approach and the characteristics of the endovascular device is essential to achieve successful revascularization in acute stroke patients with an intracranial large vessel occlusion without a direct access route to the occlusion site .
acute ischemic stroke due to embolic occlusion of the middle cerebral artery ( mca ) in patients with chronic ipsilateral internal carotid artery ( ica ) occlusion is quite rare . 
 several previous reports demonstrated that intra - arterial ( ia ) thrombolytic therapy or aspiration thrombectomy using the cross - circulation technique via an alternative collateral pathway is feasible in acute stroke patients with an unfavorable direct route to the occluded sites . 
 however , stent - retriever embolectomy via the cross - circulation approach has not been reported in the literature . 
 the present paper reports the first case of successful stent - retriever embolectomy for acute mca occlusion via the patent posterior communicating artery ( pcoma ) by using trevo xp provue stent - retriever in a patient with acute mca stroke and chronic occlusion at the origin site of the ipsilateral ica .