Reoperation for residual/recurrent aneurysms of the basilar apex

Reoperation for aneurysms associated with basilar bifurcation is exceptionally hazardous and technically challenging. De novo aneurysms involving the apex and bifurcation of the basilar artery (BA) are inherently difficult to surgically treat and the region is predisposed for technical surgical difficulty. The basilar bifurcation occurs deep within the cranial vault surrounded by vital neurologic and vascular structures. Approaches to the basilar apex usually involve a compromise between optical visualization of the operative field and the ability to work with the required instrumentation and aneurysm clips in a very confined space. Basilar apex aneurysms occur within a small anatomic region, which has finite limits dictated by the internal carotid artery, oculomotor nerve, brain stem, and skull base. Numerous small thalamoperforate vessels associated with the proximal portions of the posterior cerebral (P1) arteries supply the posterior thalamus and posterior limb of the internal capsule. These thalamoperforate vessels do not tolerate significant surgical manipulation, and patients are typically poorly tolerant of surgical injury or sacrifice of these fragile vessels. There are many reasons that residual aneurysm can occur at the basilar apex, but the most likely explanation is suboptimal clip placement during the initial attempted aneurysm repair. A portion of an aneurysm that remains incompletely treated may predispose the patient to subarachnoid hemorrhage or continued aneurysm growth at the site of the residual. Unfortunately, the presence of residual aneurysm may go unnoticed for a number of years if postoperative angiography was not performed following the initial surgical procedure. The increasingly common use of endovascular coiling in the treatment of basilar apex aneurysms has also led to technical challenges for surgically treating residual or recurrent aneurysm following coil procedures. We will address how much residual aneurysm we feel poses significant risk for continued growth and hemorrhage, and our approach to treatment of recurrence in this region. The delayed recurrence of an aneurysm involving the basilar apex poses different problems than residual aneurysm sac seen relatively soon following a surgical procedure. Recurrence of an aneurysm implies that a period of time has elapsed and new aneurysm tissue has developed, whereas residual aneurysm is defined as aneurysm tissue which was not obliterated during the initial surgical or endovascular procedure. This article will divide these problems into two distinct categories: treatment of residual aneurysms and treatment of recurrent aneurysms of the basilar apex.