Pitfall in clipping of unruptured cerebral aneurysms: narrowing of the parent artery.

Two patients with unruptured cerebral aneurysms are presented, who were complicated by transient ischaemic neurological deficits after seemingly uneventful neck clipping. Postoperative angiography disclosed narrowing of the parent arteries. Arteriosclerotic thickening of the wall of the aneurysmal neck and the parent artery was presumed to be the cause of the narrowing. To minimize the operative morbidity in patients with unruptured aneurysms, the possibility of this phenomenon should always be borne in mind. Neck clipping procedures avoiding this pitfall are discussed.