A frequent concern patients voice during the followup visit is their risk of developing another brain aneurysm.  Although the risk is, on average, low, in select situations or with certain risk factors, the risk may be higher and justify more frequent surveillance imaging and aggressive treatment if any are discovered.

Graf and Hamby[1], in 1964, when CT scans weren’t available, were the first to coin the phrase “de novo” in describing a case of a new, ruptured brain aneurysm not detected on a patient who undergone treatment for another ruptured aneurysm three years prior.  They concluded:

“The therapeutic implications here are disturbing.  We have always felt that if a single aneurysm were demonstrated by adequate bilateral carotid angiography and obliterated, the patient could be given fairly positive assurance that he would not have further difficulty.  If, however, aneurysms can arise de novo, it would seem that there is less security in assuring such a patient that the successful treatment of one aneurysm solves his aneurysm problem.”

Since this report, de novo aneurysm formation has been an extensively studied topic.  Although the overall risk is low, certain conditions may predispose, and therefore may be important for you and your physician to be aware of.[2]  An important concept to understand is that brain aneurysms are usually formed by a number of different factors that together, over time, can lead to its formation.  The key is to identify if you have a preponderance of these risk factors, what your perceived overall risk might be and if anything can be done about some of the risk factors.  This information should then ultimately guide your long-term management plan, specifically including the frequency of future brain imaging. 

Multiple reports consistently show that hypertension and smoking have been associated with forming de novo aneurysms.  Blood pressure control and smoking cessation are modifiable, albeit not easy, risk factors.  On the other hand, risk factors that are not modifiable include complete blockage of one carotid artery, or carotid artery occlusion which has also been well described as a risk factor presumably because of the shift in blood flow pattern[3].  Female gender and prior radiation exposure to the head and neck has also been described.  A strong family history of brain aneurysms and a personal history of multiple aneurysms all also are found more often in patients with de novo aneurysms.  

REFERENCES:

1. Graf CJ, Hamby WB Report of a case of cerebral aneurysm in an adult developing apparently de novo. J Neurol Neurosurg Psychiatry Apr 1964;27(2):153-156.
2. Kemp WJ, Fulkerson DH, Payner TD, Leipzig TJ, Horner TG, Palmer EL, Cohen-Gadol AA. Risk of hemorrhage from de novo cerebral aneurysms. J Neurosurg 118:58-62, 2013.
3. Bakhsh S, Toll V, Neimann D, Chen M. Spontaneous internal carotid artery occlusion and rapid aneurysm progression:  case series and literature review. Neurointervention 2014 Sep;9(2):78-82.