More dual training for neurosurgeons can improve outcomes
Although responsible for only 3%-5% of all cerebrovascular aneurysms, basilar artery aneurysms (BAAs) are among the most difficult to treat. Determining the better of two treatment options is based on several factors – and can be influenced by whether or not the physician has expertise in both procedures.
Affecting the most deep-seated artery in the brain, BAAs present a unique challenge for physicians. Accessing the artery requires navigating past critical cerebral structures and vessels. Once accessed, there is little room for error, because the blood running through this thoroughfare oxygenates the brainstem and the thalamus. Two options exist for treating this complex problem: endovascular coiling or open microsurgery clip reconstruction, which is a more invasive approach.
The preferred and most utilized treatment recently has been the use of endovascular coiling – in part because this approach does not require open surgery or working between critical brain structures and thus has demonstrated a better safety profile. Often performed by neurosurgeons, radiologists or neurologists, this technique involves threading platinum wires known as embolization coils from the femoral or radial artery up into the brain’s vasculature, and forming a coil mass inside the aneurysm that prevents blood from continuing to flow into it.
However, not all BAAs are suited for coiling. For example, using coils on BAAs with wide “necks” can result in the coils falling out and the patient requiring adjunctive procedures or possibly suffering a stroke. Other examples include BAAs with perforator or blister-like morphology, or with eloquent vessels arising from the dome. These aneurysms are better treated with open microsurgery, where metal clips are permanently placed around the base of the aneurysm to stop the flow of blood while preserving perforator patency. Although this treatment carries potentially more risk, it can be the more effective choice in many instances. Moreover, it offers the best chance for permanent occlusion with less chance of recurrence or a need for retreatment.
Physician knowledge plays a part
Oftentimes the decision on which approach to take is not based on factors concerning the BAA itself, but rather on the comfort level of the treating physician with a procedure option. Over the past 20 years, circumstances nationwide have resulted in decreased expertise in the microsurgery therapy for aneurysms.
“What we have is a double whammy,” said Adib A. Abla, MD, chief of vascular neurosurgery at UC San Francisco. “The relatively small number of BAAs overall, combined with the preference for endovascular coiling, has had a ‘snowball effect,’ leading to fewer opportunities for new neurosurgeons to be dually trained in both endovascular and microsurgery procedures for basilar artery aneurysms. The result is that many basilar artery aneurysms are treated endovascularly not necessarily when it’s the most appropriate choice but sometimes when it’s the most available.”
Dr. Abla, who is trained in and performs both procedures at UCSF, likens the advantage of dual training to a baseball batter who is equally adept batting right handed or left handed. “An ambidextrous batter, known as a switch hitter, is theoretically going to have a better chance when tailoring their batting approach to the pitcher on the mound.”
Study shows need to consider both options
Dr. Abla led a retrospective analysis that explored how treatment decisions for BAA patients might be approached by a physician who was dually trained in endovascular coiling and open microsurgery clip reconstruction. The study reviewed 42 BAA procedures that Dr. Abla performed involving 34 patients over the course of almost five years. Patients were treated with either the endovascular coiling or microsurgery clip modality. The study’s authors reviewed the various factors involved in determining which approach to pursue, including the nature of the BAA, demographics and patient preferences. The team also examined the extent to which physician expertise – or lack thereof – might play a part in decision-making.
In this published single-surgeon study – the largest known of its kind – endovascular coiling was the default treatment and accounted for 26 of 42 treatments (61.9%), while microsurgical clip reconstruction accounted for 16 of 42 treatments (38.1%). Seven of the eight re-treatments were for endovascularly treated BAAs.
Surgical treatment was employed in cases in which an endovascular approach was deemed a high risk for complication, impossible to complete without vessel/perforator sacrifice, unlikely to secure the aneurysm (most notably for ruptured aneurysms), or when it would require the use of a stent and consequently also dual antiplatelet therapy in the setting of subarachnoid
Although the authors concluded that endovascular treatment should remain the default, the fact that nearly a third of the procedures in the study were treated with microsurgery indicates that this approach should be considered when determining the best option. An informed decision can be made between the minimally invasive endovascular therapy and the more certain obliteration of the aneurysm provided by microsurgery. But more training is needed to achieve this goal.
“We found that having neurosurgeons trained in both endovascular coiling and microsurgery clipping allows them to leverage the strengths of both techniques and weigh the disadvantages and benefits of each, tailoring the strategy to the individual patient,” said Dr. Abla. “The goal should be making procedure decisions based on which modality offers the best outcome – and achieving the same safety profile for each. But that also requires the physician to be equally knowledgeable about and trained on both methods.”
In an effort to raise the technical proficiency of neurosurgeons in open microsurgery clip reconstruction for BAAs and all brain aneurysms and vascular disorders, the neurosurgery department at UCSF launched a year-long cerebrovascular fellowship that is now in its ninth year.
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