Objective: Although endovascular coiling has been used for 15 years in the treatment of intracranial aneurysms, fewer than 60 published studies have directly compared microsurgical clipping and endovascular coiling, and only two studies have used a randomized, prospective design. The objective of this review is to weigh evidence for the efficacy of endovascular coiling compared with microsurgical clipping based on published head-to-head comparisons.
Methods: Two major electronic databases, PubMed and Cochrane Library, were queried using search terms such as "coiling," "clipping," "microsurgical," "endovascular," "Guglielmi," and "intracranial aneurysm." Relevant randomized trials and observational, cohort, and case studies of unruptured and ruptured aneurysms were considered for analysis. Data from included studies were summarized qualitatively, addressing study methodologies, patient demographics, study techniques/equipment, and outcome measures.
Results: Forty-seven studies were included in the final count, including two prospective randomized trials, 23 prospective observational studies, 20 retrospective observational studies, and two studies that used a combination of prospective and retrospective data. In total, 18 studies found outcomes to be equivalent in the coiled and clipped groups, 18 studies favored coiling, 10 studies favored clipping, and one study had no conclusion (in terms of a comparison).
Conclusion: The earliest randomized prospective study by Koivisto et al. found clinical and angiographic results between the two methodologies to be statistically equivalent. The more recent and larger randomized, prospective study from the International Subarachnoid Aneurysm Trial group suggests that endovascular coiling is statistically superior to microsurgical clipping in clinical outcomes, although the recently published long-term follow-up of International Subarachnoid Aneurysm Trial patients documents higher recurrence and rehemorrhage rates after endovascular coiling. Although there is no clear consensus in these two studies or in the 45 observational studies included, clinically useful information can be extracted to improve shared decision making and interaction between interventionalists and neurosurgeons, create more individualized treatment algorithms, and enhance future research.