Residual lesions in patients who underwent microsurgical clipping of cerebral aneurysms

Microsurgical clipping is currently the main method of treating cerebral aneurysms, even with the improvement of endovascular therapy techniques in recent years. Treatment aims at complete occlusion of the lesion, which is not always feasible. Although appearing superior to endovascular treatment, microsurgical clipping may present varying percentages of incomplete occlusion. Such incidence may be reduced with the use of intraoperative vascular study. Some classifications were elaborated in an attempt to standardize the characteristics of residual lesions, but the classification criteria and terminology used in the studies remain vague and poorly documented, and there is no consensus for a uniform classification. Thus, there is also no agrement on which residual aneurysms should be treated. The aim of this study is to review the literature on residual lesions after microsurgery to treat cerebral aneurysms and how to proceed with them.