I am anxious about having an undiagnosed brain aneursym. i am a 21 year old male is it very unlikely that i would have an anuerysm that could rupture? its scary because there are no symptoms until its too late.

No worries: The chance of a particular young healthy person getting a brain aneurysm rupture in the coming 12 months is zero percent (0% chance, mathematically rounded, of course). Rare events are rare, which is fortunate for mankind. Because aneurysms usually don't appear in childhood or early adulthood, the chance of a person in his 20's having an unruptured brain aneurysm is also 0%, mathematically.