An aneurysm is a bulge or a weakening of an artery’s wall. (illustration) An aneurysm usually occurs where one main blood vessel splits into two (bifurcation) or three smaller vessels (trifurcation).

Aneurysms are thought to be caused by a congenital weakness in the muscular layer (media) of an artery. Factors like high blood pressure, atherosclerosis, and smoking are known to increase the risk of an aneurysm rupture.

Signs & Symptoms
Aneurysms may burst and cause bleeding into a covering around the brain called the subarachnoid Space. This is referred to as a subarachnoid hemorrhage. Subarachnoid hemorrhage secondary to a ruptured aneurysm causes a severe headache. The headache can be accompanied nausea, vomiting, sensitivity to light (photosensitivity), a stiff neck, double vision, difficulty speaking, difficulty swallowing, numbness or tingling of the face, arm or leg or weakness of the face arm or leg. Subarachnoid hemorrhage is an emergency and patients with symptoms should call 911.

Aneurysms may also present by placing pressure on a cranial nerve or other surrounding structures. Symptoms may include headache, double vision, change in vision, facial pain, unequal pupils, or numbness of the face.

Finally, an aneurysm may rupture causing bleeding inside the brain. Symptoms may include loss of consciousness, paralysis of the face, arm or leg, difficulty speaking, numbness of the face, arm or leg, or other complex neurological presentations.