How to best manage unruptured brain aneurysms

Modern imaging technologies have enabled physicians to peer into the living brain as never before, but the pictures often reveal structural anomalies, such as unruptured brain aneurysms, whose risks are unclear.

Unruptured brain aneurysms, bulges that form on arteries where the vessel wall is weakened, are typically discovered incidentally, with a CT or MRI scan, often when a patient is being evaluated for migraines.  They occur in about five percent of patients.   But how to proceed once the anomalies are found is not clear.  Should a patient undergo surgery to correct the problem before the aneurysm bursts, causing a life-threatening haemorrhage?  Or is it better to “wait and see” and avoid the risks of surgery?  Perhaps the aneurysm will never break.

Rush is participating in an international clinical trial designed to determine the best course of action when an unruptured aneurysm is discovered. TEAM, for Trial of Endovascular Aneurysm Management, is the first and only large multicentre study in the world examining this question. Up to 2,000 patients at about 60 centres worldwide will be enrolled and followed for 10 years.  Rush is the only medical centre in the Chicago area involved in the study.

“Learning that you have a brain aneurysm can be a traumatic experience for patients.  They may fear they are walking around with a ticking time bomb in their head,” said Dr Michael Chen, a neuroendovascular surgeon at Rush.  “But we do not really know how likely it is that a rupture will occur, or if it ever will.”

Patients who choose to enrol in the study will be randomly assigned to one of two groups.  One group will receive a minimally invasive surgical procedure called “coiling,” which involves threading a catheter through an artery in the groin and up into the brain.  Tiny platinum coils are navigated through the catheter and positioned in the aneurysm, filling the pouch to block any further blood flow into the aneurysm sac.  In a landmark study published in 2002, coiling was shown to produce better results than open surgery, called surgical clipping, when used for ruptured aneurysms, but its efficacy in preventing ruptures has not been established. Complications occur in an estimated one to five percent of patients.

The other group will be treated conservatively.  Patients will be closely monitored – perhaps more closely than they might be outside a clinical trial – through regular office visits, testing and follow-up, and measures will be taken to eliminate or control risk factors such as arterial hypertension, smoking and excessive alcohol use. The risk of the aneurysm rupturing is estimated at one-half to two percent per year, although those numbers are still debated in the medical community.

(Source: Rush University Medical Center: February 2009)