Anatomic Results

The goal of aneurysm treatment, whether it is microsurgical or endovascular, is the complete exclusion of the aneurysm sac and neck from the cerebral circu lation. The size of the aneurysm neck and its relationship to the body of the aneurysm are probably the most important determinants of the endovascular treatment result (52). Zubilaga et al. (53) demonstrated a complete occlusion rate of 85% for small neck aneurysms with a neck less than 4 mm, but only 15% for aneurysms with a neck 4mm or greater. Studying the predictors of the immediate outcome of aneurysm occlusion, Turjman et al. (54) found that large aneurysmal diameter and volume and large neck size, as well as increasingly obtuse angulation between the long axis of aneurysm and the parent artery, correlated with unsatisfactory treatment result. Besides the morphological aneurysm characteristics, the operator experience was associated with higher occlusion rates.

Aneurysm Remnant

Endovascular treatment is often incomplete. A metaanalysis of 1383 patients showed that are more than 90% occlusion rate could be achieved in 90% of treated aneurysms and a complete occlusion rate in 54% (9). Small aneurysm neck remnants are frequently seen after endovascular GDC embolization. Vin-uela et al. (18) reported aneurysm neck remnants in 21.4% of small aneurysms with small necks, 41.6% of small aneurysms, with wide necks, 57.1% of large aneurysms and 50% of giant aneurysms.

The evolution of the aneurysm rest is unclear. It may undergo thrombosis and disappear, or it may enlarge as a result of coil compaction or aneurysm regrowth. The water hammer effect of blood flow in the aneurysm inflow zone may result in aneurysm recanalization. Broad-necked aneurysms are exposed to higher intensity hemodynamic shear forces than small-neck aneurysms (55). Besides the pulsatile blood flow, scar contraction of the connective tissue that forms on the coil surface may contribute to the coil compaction (32). Large neck size and large aneurysm size were found to be associated with higher recanal-ization rates. Hayakawa et al. (56) found that denser packing of the aneurysm significantly reduces the recanalization rate. They studied the natural history of 73 coiled aneurysms with residual necks for a period of 3-71 mo (mean 17.3 mo): 25% exhibited progressive thrombosis, 26% remained unchanged, and 49% displayed recanalization on postembolization angiography.

It is not known whether the aneurysm remnants following endovascular treatment differ from surgical remnants. Malish et al. ( ) demonstrated a bleeding rate of postembolization aneurysm remnants of 0% in patients with small aneurysms, 4% in large aneurysms, and 33% in giant aneurysms in a follow-up of 2-6 yr (mean 3.5 yr). Long-term observational studies are needed to assess the evolution of the postembolization aneurysm remnants and compare it with the surgical remnants.

The reported rate of aneurysm remnants after surgical clipping ranges between 3.9 and 26% (10,58). The lack of a standardized definition for residual postoperative angiographic aneurysm filling and the differences in patient populations in different studies may partially explain these differences. In a recent metaanalysis, residual filling on postoperative angiography was found in 5.2% of 1370 surgically treated patients (59). Two large studies have investigated the natural history of surgical aneurysm remnants. David et al. (20) demonstrated a rehemorrhage rate of 1.9% per yr from aneurysm residua. Feuerberg et al. (58) reported an annual rehemorrhage rate from aneurysmal residua of up to 0.8%. Reoperation of the remnant was shown to carry a morbidity of 7% and a mortality of 5.2% (60). Endovascular treatment of aneurysm remnants is effective and can be performed without significant morbidity (61).

Aneurysm Recurrence

Aneurysm recanalization owing to coil compaction or continuous aneurysm growth can also occur in completely occluded aneurysms. Cognard et al. (62) reported a recurrence in 20 of 148 (14%) completely occluded aneurysms in an angiographic follow-up of 3-40 mo. The recurrences were more common in ruptured (17%) than in unruptured (7%) aneurysms. Intraaneurysmal thrombus may lead to coil migration and recanalization (41,62). David et al. (20) reported a 0.52% annual regrowth rate for completely clipped aneurysms and an 1.8% annual rate of de novo aneurysm formation. Tsutsumi et al. (63) found an 8% rate of de novo aneurysm formation and a 2.9% aneurysm regrowth rate at 9 yr, in a series of 220 patients with SAH, who underwent complete surgical aneurysm clipping confirmed by postoperative angiography. Rebleeding has been reported to affect 2.7% of patients cumulatively in 10 yr, even after complete aneurysm clipping (19).

All patients treated with coil embolization should have angiographic follow-up studies to assess the temporal evolution of the initial treatment result (Figs. 2 and 4).

How To Reduce Acne Scarring

How To Reduce Acne Scarring

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