General Principles of Aneurysm Surgery: Nuances and Advice for Successful Outcomes and Complication Avoidance
There are some general principles that can be applied to any microsurgical procedure for the treatment of intracranial aneurysms. These are points that have been important in achieving a successful outcome in the vast majority of cases in the author’s personal experience. It should be noted that there is rarely “one right way” to do anything in neurosurgery. What works well for one surgeon may not be appropriate for another. Nevertheless, these are some general rules that have been particularly useful to the author.
The surgeon’s struggle to achieve reliably excellent results in the treatment of intracranial aneurysms begins not in the operating room but with judicious patient selection. Treatment should be recommended for unruptured aneurysms only if the surgeon is confident that the surgery can be performed safely, given the relatively benign natural history associated with simple observation. In the setting of a ruptured lesion, the improved durability associated with surgical clipping as opposed to endovascular therapy becomes meaningless if surgery results in a poor immediate neurological outcome from which the patient never recovers. In many ways, patient selection represents at least “half the battle.”
There Is No Substitute for an Organized Plan
Although aneurysm surgery demands a certain amount of flexibility based on intraoperative findings, a good aneurysm surgeon will have an organized plan of attack, including potential contingency options should things change during surgery.
Expose What You Must, No More and No Less
Obviously, it is impossible to expose precisely and only the absolutely necessary anatomy in every operation. Nevertheless, a good neurovascular surgeon will over time develop a sense for just how much exposure is needed to complete the task at hand. This does not mean that one never increases the exposure by further opening a fissure, for example. But there is no need to open the Sylvian fissure widely to reach every anterior circulation aneurysm, and the author has seen surgeons get into trouble exposing, for example, the middle cerebral arterial branches unnecessarily to treat a carotid ophthalmic aneurysm.
Achieve Your Primary Objective First
When treating multiple aneurysms, there is usually a larger, more concerning, or even ruptured lesion as well as a smaller or asymptomatic aneurysm of lesser concern. At times, the smaller lesion must be dealt with en route to the real target. Nevertheless, one should generally avoid the temptation to treat the smaller or less concerning aneurysm first. The author has seen surgeons get into trouble with a small asymptomatic middle cerebral artery (MCA) bifurcation aneurysm, forcing them to end an operation before ever reaching the main target, such as a large anterior communicating lesion.
Use Sharp Dissection
As a general rule, sharp dissection is safer than blunt “tearing.” At the same time, we will often use gentle blunt dissection to break fine arachnoid bands during the opening of the fissure, and we have illustrated this repeatedly in the videos in this series. But once you’re working down near the aneurysm, sharp dissection with a knife or microscissors is preferred.
Don’t Force It
It’s important for an aneurysm surgeon to develop a sense of what he or she can and cannot do. These are delicate structures, and blunt force rarely works well. By maximizing dissection of the aneurysm and its surrounding structures, I often find that the clipping is rather anti-climactic. All the anatomy has already been exposed. A clip has been tested for the proper shape and size, and simply applying the clip and letting it close should be quick and easy.
Common Sense Always Rules
If it doesn’t look right, if it doesn’t feel safe, then you need to think twice. When it looks as though I haven’t adequately prepared for a situation in which I find myself, I will often tell myself, “Take a step back, and think about this …”
The neurosurgeon should always remember that there is nothing wrong with exploring an aneurysm and deciding it is too complicated to treat safely with primary clip occlusion. Although some aneurysms are better suited for open microsurgery, that fact does not absolutely preclude the possibility of an endovascular approach, at times with a stent if the parent arteries are of adequate caliber. Therefore, if a surgeon is in the operating room and cannot adequately identify the critical anatomy necessary for precise clip placement, it may be quite reasonable to stop and refer the patient for an attempt at endovascular treatment or to a more experienced microsurgeon if endovascular therapy is not considered feasible. In fact, this is generally a much better approach than to “force” the situation and potentially end up with a severe neurological injury. On many occasions, even when our endovascular colleagues had previously recommended open microsurgical treatment, we have called them to the operating room for an intraoperative consultation to discuss the potential for an endovascular approach when we have unexpectedly encountered a situation that is felt to increase significantly the risk of proceeding with direct clip reconstruction. In general, patients are warned preoperatively that there is a remote possibility that we will not primarily clip the aneurysm if the intraoperative findings alter our assessment of the “risk/benefit” profile associated with proceeding.