Treatment of cerebral aneurysms may be realized in one of two ways: via an open approach or an endovascular approach. The endovascular approach involved the insertion of a series of “coils” into the lumen of the aneurysm. The coils are intended to cause thrombosis within the aneurysm, preventing flow into the aneurysm and minimizing the risk of expansion and rupture. The advantages of the endovascular approach are obvious: it is a minimally invasive method which spares the patient from undergoing major brain surgery. But the risks of endovascular approaches-stoke, permanent neurological injury, death-are not trivial. In addition, some aneurysms are not amenable to endovascular treatment and must be clipped. Another disadvantage of coiling may be recurrence rate. In a recent paper in Neuroradiology, Grunwald et al found a 25% recanalization and recurrence rate of previously coiled aneurysms15.
Indications favoring endovascular treatment include surgically inaccessible unruptured aneurysms, clipping failure, elderly patients, a dome-to-neck ratio of 2 or greater and a neck diameter less than 5 mm.
The other major treatment option available to patients involves a craniotomy and surgical “clipping” at the base of the aneurysm. This effectively prevents the aneurysm from communicating with the parent vessel. surgical clipping of the aneurysm neck remains the gold standard treatment1, but because of the high risk of morbidity and mortality with this approach, it is most often reserved for cases in which the aneurysm is not amenable to coiling, such as in the case of wide necked aneurysms, aneurysms greater than 20 mm, or coiled aneuryms with residual filling1.
The following is from the American Heart Association Stroke Council Recommendations for the treatment of intracerebral aneurysms19:
“The existing body of knowledge supports the following recommendations (options) regarding the treatment of UIAs:
- The treatment of small incidental intracavernous ICA aneurysms is not generally indicated. For large symptomatic intracavernous aneurysms, treatment decisions should be individualized on the basis of patient age, severity and progression of symptoms, and treatment alternatives. The higher risk of treatment and shorter life expectancy in older individuals must be considered in all patients and favors observation in older patients with asymptomatic aneurysms.
- Symptomatic intradural aneurysms of all sizes should be considered for treatment, with relative urgency for the treatment of acutely symptomatic aneurysms. Symptomatic large or giant aneurysms carry higher surgical risks that require a careful analysis of individualized patient and aneurysmal risks and surgeon and center expertise.
- Coexisting or remaining aneurysms of all sizes in patients with SAH due to another treated aneurysm carry a higher risk for future hemorrhage than do similar sized aneurysms without a prior SAH history and warrant consideration for treatment. Aneurysms located at the basilar apex carry a relatively high risk of rupture. Treatment decisions must take into account the patient’s age, existing medical and neurological condition, and relative risks of repair. If a decision is made for observation, reevaluation on a periodic basis with CT/MRA or selective contrast angiography should be considered, with changes in aneurysmal size sought, although careful attention to technical factors will be required to optimize the reliability of these measures.
- In consideration of the apparent low risk of hemorrhage from incidental small (<10 mm) aneurysms in patients without previous SAH, treatment rather than observation cannot be generally advocated. However, special consideration for treatment should be given to young patients in this group. Likewise, small aneurysms approaching the 10-mm diameter size, those with daughter sac formation and other unique hemodynamic features, and patients with a positive family history for aneurysms or aneurysmal SAH deserve special consideration for treatment. In those managed conservatively, periodic follow-up imaging evaluation should be considered and is necessary if a specific symptom should arise. If changes in aneurysmal size or configuration are observed, this should lead to special consideration for treatment.
- Asymptomatic aneurysms of 10 mm in diameter warrant strong consideration for treatment, taking into account patient age, existing medical and neurological conditions, and relative risks for treatment.”
There remains a good deal of debate over the issues of early versus late treatment of aneurysms. Students interested in learning more are directed to Greenberg’s Handbook of Neurosurgery, Sixth Edition pp. 804-805.