Surgical Strategies for Giant Intracranial Aneurysms
Untreated giant intracranial aneurysms have a dismal natural history as a result of hemorrhage, cerebral compression, and thromboembolism. The poor prognosis of patients with giant aneurysms therefore warrants aggressive treatment. A surgical approach is
- PDF / 2,956,708 Bytes
- 16 Pages / 595.278 x 793.684 pts Page_size
- 12 Downloads / 225 Views
High-quality, four-vessel cerebral angiography is essential in the preoperative evaluation of patients with giant aneurysms. Angiography provides detailed information about the aneurysm's location, anatomy, adjacent branch vessels, collateral circulation, and distal cerebral perfusion. Angiography only shows luminal filling, which may not represent the true size of the aneurysm. Layers of laminated thrombus frequently make giant aneurysms much larger than they appear on angiography alone. CT scans often demonstrate a calcified, eggshell border that defines the true diameter of the aneurysm. MR images demonstrate a signal void within a patent lumen. Alternating high- and low-intensity signals on Tl-weighted images correspond to hemosiderin and methemoglobin within the layers of thrombus. These preoperative studies are used to determine whether the aneurysm is amenable to direct clipping and which surgical approach would optimize exposure. Two-thirds of the giant aneurysms in this patient series were located in the anterior circulation, and one-third were located in the posterior circulation. Of the anterior circulation aneurysms, the aneurysms of the middle cerebral artery (MCA) were the most common (25%). Aneurysms on the ophthalmic segment of the internal carotid artery (ICA; including the ophthalmic artery, superior hypophyseal artery, and paraclinoid aneurysms) accounted for another 25%. In decreasing order of frequency, other anterior circulation locations were the cavernous ICA (15%), anterior cerebral artery (ACA; 13%), ICA bifurcation (8%), communicating segment ofICA (8%), and petrous ICA (3%). In the posterior circulation, the basilar artery apex was the most common giant aneurysm location. Seventy percent of these aneurysms were at the basilar tip, PI segment of posterior cerebral artery (PCA), or the superior cerebellar artery (SCA). Midbasilar artery aneurysms (18%) and vertebral artery aneurysms (including vertebrobasilar junction and posterior inferior cerebellar artery (PICA) aneurysms; 12%) were less commonly encountered. Preoperative Management
Patients who presented with SAH were managed using the same principles and protocols that have been established for other patients with SAH [4]. Blood pressure was controlled carefully to minimize the risk of rupture. Ventriculostomy with cerebrospinal fluid drainage was used to treat patients with Hunt and Hess grades IV and V, and measurements of intracranial pressure (ICP) were used to guide surgical decisions [5]. ICP elevations were managed aggressively with conventional methods. Surgery was performed within 24 hours of presentation in suitable patients. Surgical Treatment
With the exception of three frontal-interhemispheric approaches for ACA aneurysms, a pterional or orbitozygomatic approach was used in patients with anterior circulation giant aneurysms. The orbitozygomatic approach was only used in 10% of these cases, but its use has increased in recent years. A wider variety of approaches was used for giant aneurysms of the posterior circulation.
Data Loading...
