Long-term follow-up survey reveals a high yield, up to 30% of patients presenting newly detected aneurysms more than 10 years after ruptured intracranial aneurysms clipping.

The need to pursue long-term follow-up in patients treated for a ruptured aneurysm remains debated. New aneurysms development is a crucial element to consider but remains scarcely analyzed especially after a mean follow-up longer than 10 years. Our study was designed to provide rates of newly developed aneurysms in patients who have undergone prior clipping who were not followed with serial imaging. Patients were included if they were (1) treated more than 10 years ago by clipping of a ruptured aneurysm, (2) independent at time of discharge, (3) presently younger than 65 years, and if (4) they agreed to undergo a late digital subtraction angiography (DSA) control or to transmit results of a recent one performed elsewhere. Twenty patients were included with a mean delay between aneurysm treatment and late DSA of 18.0 years (10-26.5 years). Out of these patients, six (30%) harbored new aneurysms. Of these six individuals, four (66.6%) presented multiple aneurysms with a total of 15 newly discovered aneurysms. Aneurysm sizes ranged from 1 to 10 mm. One patient suffered from a de novo aneurysm rupture. Multiple aneurysms at the time of the first hemorrhage were a risk factor in developing de novo aneurysm (p=0.0175). In conclusion, based on a 30% rate of new aneurysm formation in patients clipped more than a decade ago, close screening on a very long-term perspective is encouraged. This study suggests aneurysm formation to be a continuous process.