The purpose of this study is to assess safety and effectiveness of the p64 Flow Modulation Device.

Title: Diversion-p64. Device: p64 Flow Modulation Device. Study design: Prospective, multicenter, single arm Post Market Clinical Follow-Up Study.

Purpose: To assess safety and effectiveness of p64. Study duration: 48 months. Sample Size: 400 patients. Number of sites: > 20. Follow-up intervals: Two independent follow-ups (after 3-6 and 7-12 months) according to site specific standard.

Inclusion Criteria

1. Age ≥ 18
2. Patient harbours either one saccular or one dissecting or one blisterlike or one fusiform intracerebral aneurysm or one intracerebral segmental disease, in the anterior circulation for which the indication for p64 treatment is given
3. Patient or legal representative provides written informed consent verifying that he/she consents to the use of his/her data (according to the data protection laws)

Exclusion Criteria

1. Aneurysms of the posterior circulation
2. Imaging evidence of bifurcation aneurysms
3. Imaging evidence of dissections
4. Imaging evidence of fistulae
5. Imaging evidence of arteriovenous malformations
6. Patient is harbouring another aneurysm that has to be treated within six months after first procedure
7. Known allergy to study medication, e.g. ASA, Clopidogrel, Heparin or contrast media
8. Confirmation of positive pregnancy test according to site specific standard of care (e.g. test, verbal communication)
9. Current involvement in another study or trial
10. Parent vessel treated with other Flow Diverters than p64 during intervention and re-treatment

The target population for this non-interventional study are patients with ruptured or unruptured aneurysms and segmental diseases in the anterior circulation. Patients can be included in the study if they meet all of the inclusion and none of the exclusion criteria and have provided written informed consent.