Are coil compaction and aneurysmal growth two distinct etiologies leading to recurrence following endovascular treatment of intracranial aneurysm?

BACKGROUND: Recurrence following endovascular treatment of intracranial aneurysm is attributed to either coil compaction or aneurysm growth but these processes have not been studied as distinct processes. METHODS: The pixel size of the coil mass and aneurysm sac, and the adjacent parent artery were measured and expressed as a ratio to the pixel size of the parent vessel diameter on immediate post-procedure and follow-up angiograms. Increase of aneurysm area or decrease in coil mass of 30% or greater on follow-up angiogram was used to define "significant" aneurysm growth and coil compaction, respectively. RESULTS: Eleven patients had coil compaction, 14 patients had significant aneurysm growth and 4 patients had small aneurysm regrowth. Retreatment was performed in the 14 patients with "significant" aneurysm regrowth and 8 of the 11 patients with coil compaction at mean follow of 11 months (range 5-20 months) following the initial procedure. There were no events of new aneurysmal rupture in either 11 patients with coil compaction or 14 patients with significant aneurysm regrowth over a mean follow-up period of 22 months (range of 9-42 months). CONCLUSION: This is one of the first studies to differentiate coil compaction and aneurysm growth as distinct etiologies for aneurysm recurrence.

The natural history of "contrast stasis" within aneurysm after embolization.

OBJECTIVE: Contrast stasis within residual aneurysm sac is sometimes seen after embolization of intracranial aneurysms and is thought to represent sluggish flow prone to thrombosis. We report the short- and intermediate-term angiographic outcomes of intra-aneurysmal contrast stasis following predominantly bioactive coil embolization procedures. DESIGN/METHODS: Contrast stasis was identified by retrospective review of 153 consecutive patients treated at two centers with endovascular embolizations for intracranial aneurysms. Contrast stasis was defined by persistent opacification despite clearance of contrast from parent artery assessed during angiography at 3-5 frames/second. The contrast stasis were classified based on relative area and location visualized on dynamic angiographic images as small (5-15% of the total aneurysm), large (> 15%), or occurring only in the aneurysm neck by an independent reviewer. RESULTS: There were 44 patients (23 women: mean age 54.3±12.5 years) who had contrast stasis; 36 patients had small and 8 had contrast stasis in the neck of the aneurysm. There were no patients with large contrast stasis. Of these 44 patients, 33 patients had a mean follow up angiogram in 269.5 days; 10 patients had no follow up. In 21 patients, (18 were small and 3 were in the neck) the area of contrast stasis had spontaneously thrombosed while in 7 patients there was no change in the contrast stasis. The remaining 5 patients had increase in area of contrast stasis and required re-embolization. Size of the contrast stasis (p= 0.02) was the only statistically significant factor although there was a trend dome to neck ratio > 2 (p= 0.16) and washout on the initial angiogram (p= 0.16) affecting the thrombosis of contrast stasis. CONCLUSIONS: Most small contrast stasis following coil embolization procedures spontaneously thrombose and do not require further treatment. A small proportion of patients had increase in the area of intra-aneurysmal contrast stasis and required further treatment. ABBREVIATIONS: MRAmagnetic resonance angiographyDSAdigital subtraction angiography.