Another approach to increasing complete obliteration rates involves the deployment of biologically active rather than pure platinum coils.146 Although uncontrolled studies suggest a potential reduction in the risk of recurrence, these data are preliminary and have yet to be confirmed in prospective controlled trials.147,148 Thus, although the short-term efficacy of endovascular coil obliteration is well established compared with microsurgical approaches, close long-term surveillance continues to be warranted, because durability remains a Given this delicate balance between safety and durability, there have been multiple efforts to identify subgroups of patients who might be best treated with endovascular or microsurgical techniques. 