Intracranial aneurysms: review of current treatment options and outcomes

Abstract

Intracranial aneurysms are present in roughly 5% of the population, yet most are often asymptomatic and never detected. Development of an aneurysm typically occurs during adulthood, while formation and growth are associated with risk factors such as age, hypertension, pre-existing familial conditions, and smoking. Subarachnoid hemorrhage, the most common presentation due to aneurysm rupture, represents a serious medical condition often leading to severe neurological deficit or death. Recent technological advances in imaging modalities, along with increased understanding of natural history and prevalence of aneurysms, have increased detection of asymptomatic unruptured intracranial aneurysms (UIA). Studies reporting on the risk of rupture and outcomes have provided much insight, but the debate remains of how and when unruptured aneurysms should be managed. Treatment methods include two major intervention options: clipping of the aneurysm and endovascular methods such as coiling, stent-assisted coiling, and flow diversion stents. The studies reviewed here support the generalized notion that endovascular treatment of UIA provides a safe and effective alternative to surgical treatment. The risks associated with endovascular repair are lower and incur shorter hospital stays for appropriately selected patients. The endovascular treatment option should be considered based on factors such as aneurysm size, location, patient medical history, and operator experience.

Keywords: aneurysms; clipping; coiling; endovascular surgery; flow diversion; stents; subarachnoid hemorrhage.

Figure 1

Clipping of MCA aneurysm. A 49-year-old woman presented with subarachnoid hemorrhage. (A) Cerebral angiography demonstrated a 6-mm right MCA bifurcation aneurysm. Like most MCA aneurysms, this lesion had a wide neck involving the origins of the insular (M2) MCA divisions. (B) A right frontotemporal craniotomy and sylvian fissure opening was performed with microsurgical exposure of the aneurysm. (C) A single clip was applied across the aneurysm neck. (D) Postoperative angiography confirmed complete clipping (arrows) of the aneurysm.

Figure 2

Recanalized aneurysm. A 59-year-old man presented with SAH found to have multiple aneurysms including a giant anterior communicating artery (ACoA) aneurysm. He underwent primary coil embolization initially. (A) Anterior–posterior (AP) view of a right ICA injection shows coil mass in the giant aneurysm (arrow). There is still some residual filling of the aneurysm. (B) Lateral view shows the residual aneurysm more clearly (arrows). The anterior cerebral arteries (ACA) were difficult to separate from the aneurysm on the angiogram, and the aneurysm was underpacked in order to preserve these arteries. Follow-up angiography was performed 6 months after the patient made a good neurological recovery. (C) Lateral view of the right ICA injection shows significant recanalization of the dome of the aneurysm (arrow). (D) The patient underwent retreatment of the aneurysm with stent placement from the A1 segment of the right ACA into the A2 segment of the left ACA. This was followed by additional coil placement including gel coated coils. Subtracted view of the right ICA injection shows a dense coil mass in the giant aneurysm (arrow). Also note some recanalization of the right MCA aneurysm neck (arrowhead).

Figure 3

Balloon assisted coil embolization. A 74-year-old man with a strong family history of aneurysmal SAH was found to have a left ophthalmic aneurysm. (A) Lateral view of a left ICA injection shows a 7.5-mm left ophthalmic artery aneurysm (circled) with a 4.2-mm neck. The patient underwent balloon assisted coil embolization. (B) Lateral fluoroscopic view shows the inflated balloon (arrow) with coils being deployed through a microcatheter within the aneurysm. (C) AP view of the final left ICA injection shows no residual aneurysm.

Figure 4

Stent-assisted coil embolization. A 64-year-old woman with headaches and a family history of aneurysms underwent screening and a basilar apex aneurysm was discovered. (A) AP view of a right vertebral artery (VA) injection demonstrates the wide neck aneurysm (arrow). The neck incorporates the origin of the left posterior cerebral artery (PCA). (B) A Neuroform stent (Boston Scientific, Natick, MA, USA) delivery system positioned with the proximal and distal markers (circles) visible on fluoroscopy. Coils were introduced into the aneurysm through a separate microcatheter. (C) Final AP view shows near total occlusion of the aneurysm and preservation of the left PCA.