Flow diverter device placement for cerebral aneurysm is not effective for the patient with parent artery occlusion for contralateral aneurysm

Purpose: There have been many reports on the risks of enlargement and rupture of residual aneurysms and de novo aneurysm formation in the contralateral internal carotid artery after parent artery occlusion (PAO). In the present study, we investigated the efficacy of flow diverter device placement (FDDP) for the treatment of contralateral internal carotid artery aneurysms after PAO. Methods: After 11 patients, who had bilateral large or giant internal carotid aneurysms, were treated for either side with PAO or FDDP, they underwent FDDP for residual lesions in our hospital between October 2015 and June 2018. The patients were divided into two groups, depending on the prior procedure: PAO or FDDP. The embolic state after subsequent FDDP was evaluated by angiography. The embolic state was graded using the O'Kelly Marotta scale. Patients' characteristics and the embolic state of intracranial aneurysms after FDDP were compared between the two groups. Results: Comparing patients' characteristics between the PAO group and FDDP group, statistically significant differences were observed in laterality of the lesions and the interval between prior treatment and FDDP for residual aneurysms (p < 0.05). The embolic state at the one-year follow-up revealed that there could be significantly sufficient embolisation in the FDDP group (p < 0.05). Conclusion: When FDDP is performed for the contralateral lesion after PAO treatment, it is difficult to attain sufficient embolisation of intracranial aneurysms because haemodynamic load in this procedure is large compared to that in a regular FDDP.