An intracranial aneurysm is condition in which the wall of a small artery in the brain becomes weakened.  As it weakens, it stretches, and, in most cases, takes the shape similar to a balloon or sphere.  These occur in about 2 – 4% of the population.  The most common location for this type of aneurysm is in the base of the brain in the anterior communicating artery and the internal carotid artery. 

Most aneurysms cause no symptoms, and remain undetected.  The most common symptoms occur when the aneurysm ruptures (or bursts like the popping of a balloon) with often catastrophic consequences.   It is estimated that some 15 million Americans unknowingly live with this condition.  Ruptures occur randomly, though high blood pressure and smoking are known to increase the risk of rupture.  The symptoms of a rupture include severe headache (‘The worst headache of life’), nausea/vomiting, neck pain, and new neurologic deficits (including double vision, facial numbness or weakness).  Some patients become comatose when their aneurysm ruptures, while others may have seizures.

Intracranial aneurysms are diagnosed with imaging studies, usually CT or MRI. Rupturing of intracranial aneurysms account for 5 to 15% of all strokes.  Of these, 32 to 67% are fatal.  Other long-term complications include, excessive fluid on the brain in 12%, brain swelling in 12%, and seizures in 5%.  The most dangerous complication is recurrent bleeding, which occurs in 11% of survivors, and is fatal in 40 to 78% of cases. 

Physicians specially trained to treat aneurysms can discuss different types of treatments, including microsurgical clipping or endovascular coiling.  The type of treatment depends upon the aneurysm size, location, and shape, as well as the overall health of the patient. 

Kevin White, Justin F. Fraser, MD 


Bradley, (2008) Neurology in Clinical Practice, 5th ed.  Butterworth-Heinemann, Philadelphia: PA.

Mettler, (2005): Essentials of Radiology, 2nd ed. Saunders, Philadelphia:PA.