Evolution of open surgery for unruptured intracranial aneurysms over a fifteen year period–increased difficulty and morbidity

Published:November 25, 2022DOI:


      • Unruptured intracranial aneurysms are increasingly treated endovascularly, becoming the most common modality since 2004.
      • In the past 15 years, Open surgical clipping has decreased over time for unruptured aneurysms.
      • Patients who were treated for unruptured aneurysms had a higher number of pre-existing comorbidities.
      • Racial and socioeconomic disparities present in UIA management, with more private insurer patients undergoing craniotomy compared to endovascular cases.



      The approach to intervention for unruptured intracranial aneurysms (UIAs) remains controversial. Utilization of endovascular techniques for aneurysm repair increased dramatically during the last decade. We sought to analyze recent national trends for electively treated (open and endovascular) UIAs focusing on pre-existing patient disease burden and intervention modality selection.


      The Nationwide Inpatient Sample (NIS) national database was used to identify patients with primary diagnosis codes of unruptured intracranial aneurysm between 1999 and 2014. Patients were dichotomized by intervention into endovascular or open surgical treatment. Analysis of pre-existing disease severity were calculated using the Elixhauser comorbidity index. Complications of combined peri-procedural stroke or death during admission and hospital length of stay were used as primary endpoints for comparison.


      The percent of total UIAs treated electively with open approach decreased from more than 95 % of cases in 1999 to less than 25 % in 2014. Patients undergoing clipping were 3 years younger than those in the endovascular group (p < 0.001). The rate of primary endpoint complications (stroke and death) and length of stay for open cases saw a decrease throughout the study but remained statistically higher when compared to the endovascular group over the study period (p < 0.001). Additionally, non-neurologic complications increased over the time period for open cases. The average preoperative co-morbid disease severity for all groups treated increased over this interval. Conversely, the relative volume of endovascular cases increased but the rate of complications and average group disease remained statistically lower than the surgical clipping group (p < 0.05).


      The percent of UIAs treated electively with open approach has decreased since 1999 with a concomitant increase in complication rate in particular compared to endovascular cases. However, the health characteristics of patients treated with surgical clipping show an increase in severity of pre-existing co-morbidities. Further research into factors contributing to this finding, including potential socioeconomic differences and changes in surgeon experience are needed.


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