Contralateral intracranial aneurysm formation as a late complication of carotid ligation

Ligation of the carotid artery was the treatment of choice for intracranial aneurysms for many years. While the literature recognizes many complications associated with this procedure, the late occurrence of aneurysms on the side opposite the ligation is only mentioned briefly. Animal studies are reviewed in an attempt to explain a possible cause of this observed phenomenon. The 3 cases presented seem to indicate that this complication may be more common than has been previously realized.