Hypothetically, a prolonged perioperatively extraluminal and periinterventionally intraluminal cerebrovascular manipulation represents a more intense stimulus for an excessive NPY release from the NPY-containing perivascular nerve fibers around the major cerebral vessels than the ‘temporary’ moment of the aneurysm and vascular wall rupture (of the Tunica intima, Tunica media, and Tunica adventitia), respectively (at least into serum). This evidence concerns the gene NPY and aneurysm.