Dr. David Langer (rt.), Director of Cerebrovascular Surgery
and Dr. John Miller (left) - Neurovascular Surgery
A cerebral aneurysm
Cerebral arterial aneurysms are relatively uncommon lesions with an estimated frequency of 1-8% in the general population. Cerebral aneurysms consist of dilitations of the cerebral arteries and occur most commonly at branch points within the vasculature of the brain. They are thought to be acquired lesions related to hemodynamic stresses placed upon the branch points and bends in the cerebral arteries. Aneurysms can present in one of three ways: they can be discovered incidentally during MRI or angiography, they can rupture causing subarachnoid or parenchymal brain hemorrhage, or they can present with symptoms of mass effect on neural structures.
For more information about aneurysms, click to go to The Brain Aneurysm Foundation website.
Subarachnoid hemorrhage (SAH) is a disease with very high morbidity and mortality with mortality alone in the first month after SAH in all patients, treated and untreated approaching 50%. Patients who present to the hospital after SAH often complain of "the worst headache in their life" a sina qua non of aneurysmal bleed. The risk of bleeding from an unruptured aneurysm has been extensively studied with the historically accepted rate of approximately 1% per year. A recent New England Journal study suggests that the risk of bleeding is somewhat lower than this number however we believe that given the high risk of neurologic injury or death from SAH that most aneurysms in healthy individuals younger than 65 years ought to be treated rather than ignored.
Cerebral aneurysms are weaknesses in the walls of the blood vessels of the brain, usually occurring at their branch points. Aneurysms may also occur on blood vessels supplying AVMs of the brain. Aneurysms may also be found on MRI and CT scans of the brain done for other reasons. These abnormalities often present with bleeding into the fluid spaces surrounding the brain, or into the brain itself. This hemorrhage usually causes a profound headache which is described by the patient as "the worst of my life".
These are dangerous lesions which should be treated soon after discovery, if possible. They may be treated successfully by surgically exposing the lesion and then placing a clip across the aneurysm's neck, closing its communication with the artery proper. More recently, aneurysms have been successful treated using injectable "coils" with GDCO through a catheter within the artery. Open "clipping" is a safe and effective procedure with a long track record of success. Endovascular coiling is a newer technique offered at a limited number of centers in North America. It may be used in certain patients when treatment with surgery is difficult, the patient's medical condition won't allow a major surgery, or when preferred by the patient. A small number of aneurysms cannot be treated by "clipping" or "coiling",
and require blocking of the artery supplying the aneurysm. Certain
patients in this latter group may need a connection established
from an artery outside the skull to one inside (a so called by-pass
procedure or, EC-IC).