Pathophysiologically, the neurotransmitter CGRP is supposed to be released from the perivascular nerve terminals, either induced by the blood in the subarachnoid space [76] or, possibly, caused by the direct affection or disruption of the neuropeptide-containing nerve fibers at the moment of aneurysm rupture and the subsequent inhibition of neuropeptide reuptake at the nerve-ending terminals. This evidence concerns the gene CALCA and aneurysm.