rete mirabile ( " wonderful net " in latin ) is a kind of arterial plexus . carotid rete mirabile ( crm ) is one of the collateral patterns formed in the occlusion of the internal carotid artery ( ica ) . crm is classically defined to be present at carotid cavernous portion and fed by external carotid artery branches , especially internal maxillary artery ( i m a ) ( 1 ) . in spite of its rarity , the rete mirabile has clinical implications in cerebral ischemia or hemorrhage ( 2 , 3 ) . although the vertebral artery ( va ) rete mirabile associated with bilateral crm has been reported ( 1 ) , to our knowledge , symptomatic va stenosis associated with bilateral crm has not yet been reported . we report the long - term clinical and angiographic outcome after stenting for symptomatic va stenosis in the patient with bilateral crm . the institutional review board approved the retrospective review of this case and waived the patient informed consent . a 22-year - old woman suffered recurrent syncope with increasing frequency , which occurred three times in a week just before admission . all syncope episodes accompanied loss of consciousness for 1 to 2 minutes . she had a mild dull - type headache and nausea for a half day after every episode . she had been healthy before this episode , and no specific diseases were present in her family . catheter angiograms revealed a typical appearance of bilateral crm : bilateral ica cavernous segments were absent and arterial plexus ( rete mirabile ) around the cavernous segments reconstituted normal - looking supraclinoid ica ( 1 ) . the arterial plexus received their supply from the occluded ica , i m a , and middle meningeal artery . the ophthalmic arteries ( oa ) were markedly dilated on both sides and also supplied the supraclinoid ica by connecting to the rete mirabile . the right va was occluded , and the left va showed about 85% stenosis at v4 portion , which gave collateral supply to the bilateral anterior hemisphere through the posterior communicating arteries ( pcoma ) ( fig . were performed with voyager rx coronary dilatation catheter 1.5/12 mm and multi - link vision coronary stent system 4/12 mm ( abbott vascular , abbott park , il , usa ) . the post - stenting angiogram showed a significant increase in the collateral supply to the bilateral anterior hemisphere via pcoma . thereafter , the patient had no recurrence of syncope during the clinical follow - up of 50 months . on the 6-month and the 4-year follow - up angiograms , the bilateral crm regressed to a faint visualization angiographically , and the stented left va was entirely responsible for blood supply to the whole brain without any in - stent restenosis ( fig . angiographic findings generally accepted for the characteristic features of crm are as follows : 1 ) hypoplastic ica ; 2 ) arterial plexus between the maxillary artery and the cavernous portion of the ica ; 3 ) dilated oa ; 4 ) supraclinoid ica was not hypoplastic and was fed by the arterial plexus and the oa ; 5 ) bilateral lesions ; and 6 ) no abnormal vessels such as moyamoya vessels in the intradural circulation ( 1 ) . our case fully met the angiographic criteria of crm and also had a severe degree of stenosis of the left va with contralateral va occlusion . crm was considered as a secondary change to ica regression in the early development or perinatal age when the embryonic arteries were no longer available . based on this concept and the symmetric feature of crm , some authors raised the possible presence of a specific trigger or signal to initiate the regression ( 1 , 4 ) . present but hypoplastic bony carotid canals can be regarded to support this " late regression theory " , which is the most accepted one ( 1 , 3 , 4 ) . unfortunately , we could not check the patient 's carotid bony canals due to the lack of any brain ct scan , but the source images of the mr angiogram showed probable hypoplastic bony canal ( fig . it was a deliberating problem whether the lesion of bilateral va could be a sort of vertebral rete mirabile ( vrm ) . all of the lesions shown in both icas and vas for our case may fall into one category of chronic steno - occlusive disease with prominent collaterals . a few patients with both crm and vrm have also been reported ( 1 , 4 , 5 ) ; however , incomplete agreement on the angiographic features of vrm due to its rarity exist . in addition , judging from the fact that most vrm have the segmental absence of their transdural part like crm ( 4 ) , vrm could be inferred to have the similar developmental mechanism to crm . however , which different trigger or mechanism can make a ' concomitant ' development of crm and vrm has not been clarified . in this sense , we cautiously supposed that the lesions of the bilateral va in our case might be an ongoing process or a specific type of vrm although no proof to support this hypothesis exists . however , its clinical importance is being emphasized by crm cases presenting with cerebral hemorrhage or ischemia ( 2 , 3 ) . for cerebral ischemia , research needs to focus on the condition of the collaterals , and so some authors suggested the necessity of proper blood pressure control not too low or some procedures that improve the collaterals ( 2 , 5 ) . in our case , the supraclinoid icas were receiving their arterial blood flow not only from crm but also the posterior circulation through bilateral pcoma . under this condition , the right va occlusion and blood perfusion to both anterior and posterior cerebral circulation became so compromised that it could be a potent cause for the patient 's recurrent syncope . in the crm patient , as commented , it was so important to maintain sufficient collateral circulation that the stenotic left va should be corrected to improve the whole cerebral perfusion . this inference was quite reasonable when considering that an immediate augmentation of collateral supply to both icas via pcoma was possible after stent insertion . in addition , it also strongly supported the inference that the bilateral supraclinoid ica flow became independent of crm after stenting and the patient had no recurrence of syncope during the long - term follow - up . as for its developmental mechanism , such post - stent independence might be taken for evidence that the rete mirabile were formed as collaterals to the acquired segmental occlusion but not primarily . this report is , to our knowledge , the first case of symptomatic va stenosis associated with bilateral crm that was treated with stenting . although most of the bilateral crm may be asymptomatic and incidentally found , the compromised cerebral circulation can be a significant manifestation of crm therefore , it is important to carefully inspect the patient 's collateral circulation because the correction of compromised collaterals can lead an improvement in the patient 's clinical condition .
symptomatic vertebral artery ( va ) stenosis associated with bilateral carotid rete mirabile ( crm ) has not been reported . 
 we report the long - term clinical and angiographic outcome after stenting for symptomatic va stenosis in the patient with bilateral crm . 
 this report is the first case that symptomatic va stenosis associated with bilateral crm was treated with stenting .