Cerebral Aneurysm - Treatment - Benefits and Risks

Benefits and Risks

At this point it appears that the risks associated with surgical clipping and endovascular coiling, in terms of stroke or death from the procedure, are the same. The ISAT trials have shown, however, that patients who have experienced aneurysmal rupture have a 7% lower mortality rate when treated by coiling than patients treated by clipping, when all other factors are equal but the rate of rebleeding is almost 8 years higher to clipping. Coiled aneurysms, however, do have a higher recurrence rate as demonstrated by angiography. For instance, the 2007 study by Jacques Moret and colleagues from Paris, France, (a group with one of the largest experiences in endovascular coiling) indicates that 28.6% of aneurysms recurred within one year of coiling, and that the recurrence rate increased with time. These results are similar to those previously reported by other endovascular groups. For instance Jean Raymond and colleagues from Montreal, Canada, (another group with a large experience in endovascular coiling) reported that 33.6% of aneurysms recurred within one year of coiling. The most recent data from Moret's group reveals even higher aneurysm recurrence rates, namely a 36.5% recurrence rate at 9 months (which breaks down as 31.1% for small aneurysms less than 10 mm, and 56.0% for aneurysms 10 mm or larger). However, no studies to date have shown that the higher angiographic recurrence rate equals a higher rate of rebleeding. Thus far, the ISAT trials listed above show no increase in the rate of rebleeding, and show a persistent 7% lower mortality rate in subarachnoid hemorrhage patients who have been treated with coiling. In ISAT, the need for late retreatment of aneurysms was 6.9 times more likely for endovascular coiling as compared to surgical clipping. Furthermore, data from the ISAT group in March 2008 indicates that the higher aneurysm rate of recurrence is associated with a higher rebleeding rate, given that the rebleed rate of coiled aneurysms appears to be 8 times higher than that of surgically treated aneurysms in the ISAT study.

Therefore it appears that although endovascular coiling is associated with a shorter recovery period as compared to surgical clipping, it is also associated with a significantly higher recurrence rate after treatment. The long-term data for unruptured aneurysms are still being gathered.

Patients who undergo endovascular coiling need to have several serial studies (such as MRI/MRA, CTA, or angiography) to detect early recurrences. If a recurrence is identified, the aneurysm may need to be retreated with either surgery or further coiling. The risks associated with surgical clipping of previously-coiled aneurysms are very high. Ultimately, the decision to treat with surgical clipping versus endovascular coiling should be made by a cerebrovascular team with extensive experience in both modalities.