A Comparative Analysis of the Endoscopic Endonasal and Pterional Approaches for Clipping Anterior Communicating Artery Aneurysms on Three-Dimensional Printed Models
Anterior communicating artery (ACoA) aneurysms represent the largest proportion of intracranial aneurysms and are the most prone to rupture. The primary treatment methods for these aneurysms are endovascular embolization and traditional craniotomy clipping. Over the past two decades, endovascular embolization has become the preferred treatment for intracranial aneurysms in many medical centers due to advancements in interventional materials and technologies. However, some aneurysms still require traditional craniotomy clipping. With the rapid development of transsphenoidal endoscopic technology, a few neurosurgeons have begun to explore the use of the endoscopic endonasal approach (EEA) for clipping intracranial aneurysms. This approach is particularly relevant because intracranial aneurysms are mostly located within the circle of Willis and occur on the ventral side of the skull base. Despite this, the number of reported cases in the literature remains small, and more anatomical studies are needed to thoroughly analyze the approach and technique.
Three-dimensional (3D) printing technology has emerged as a valuable tool for creating specialized models for medical teaching and pre-operative preparation. To further investigate the feasibility and effectiveness of the EEA for clipping ACoA aneurysms, this study utilized 3D printing to produce models of the relevant skull base structures. These models were used to compare and analyze the EEA and the conventional pterional approach (PA) for clipping ACoA aneurysms.
The study protocol was approved by the Institutional Ethical Committee and adhered to the Declaration of Helsinki. The inclusion criteria were patients over 18 years of age with unruptured ACoA aneurysms admitted to Guangdong Provincial People’s Hospital between July 2019 and December 2019. Exclusion criteria included multiple intracranial aneurysms, ruptured ACoA aneurysms, or other intracranial diseases such as tumors, inflammation, hydrocephalus, and arteriovenous malformations. Raw data from 35 patients with unruptured ACoA aneurysms were collected, and informed consent was obtained from the patients or their families for the use of imaging data in this study.
The mean age of the patients was 59.7 years, with 37.1% females and 62.9% males. The mean aneurysm size was 5.94 mm, with small aneurysms (2-5 mm) accounting for 42.9%, medium aneurysms (5-10 mm) for 45.7%, and large aneurysms (>10 mm) for 11.4%. The vast majority (91.4%) of the aneurysms were wide-necked. The bilateral A2 was in the sagittal position in 51.4% of cases and in the horizontal position in 48.6% of cases. ACoA aneurysm projection was categorized as anterior (17.1%), posterior (5.7%), superior (20.0%), inferior (22.9%), and lateral (34.3%).
The EEA was performed on all aneurysm models, and two major indexes were assessed: the exposure rate of the aneurysm neck without instrumental assistance and the clipping success rate. These indexes were analyzed based on aneurysm size, dome projection, and the bilateral A2 position. Significant differences were observed in the exposure rate among aneurysms of different sizes, with small aneurysms having the highest exposure rate (73.3%). There was no significant difference in the exposure rate with regard to dome projection and the bilateral A2 position.
The clipping success rate also varied significantly with aneurysm size, with small aneurysms achieving the highest success rate (86.7%). Regarding dome projection, aneurysms projecting laterally had the highest success rate (91.7%). There was no significant difference in the clipping success rate with regard to the bilateral A2 position.
The surgical effects of the EEA and PA were compared using four main indicators: surgical freedom, bilateral A1 and A2 exposure, aneurysm neck exposure, and simulation clipping. The PA demonstrated significantly greater surgical freedom in both horizontal and vertical directions compared to the EEA. The exposure length of the ipsilateral A1 was significantly greater in the PA than in the EEA, while the exposure length of the contralateral A1 was greater in the EEA. The exposure length of bilateral A2 was less in the EEA than in the PA. In the absence of instrumental assistance, there was no significant difference in the aneurysm neck exposure rate between the EEA and PA.
Further analysis revealed that for aneurysms of different sizes, there was no significant difference in the exposure rate between the EEA and PA. However, there was a significant difference in the exposure rate between the EEA and ipsilateral PA when the aneurysm projected superiorly. There was no significant difference in the exposure rate between the EEA and contralateral PA. When the bilateral A2 was in the sagittal position, there was a significant difference in the exposure rate between the EEA and ipsilateral PA.
The simulated ACoA aneurysm clipping success rate was significantly higher in the ipsilateral PA (100.0%) compared to the EEA (74.3%). There was no significant difference in the clipping success rate between the EEA and contralateral PA. In small and medium aneurysms, there was no significant difference in the clipping success rates between the EEA and ipsilateral PA or between the EEA and contralateral PA. However, in large aneurysms, there was a significant difference in the clipping success rate between the EEA and ipsilateral PA. When the aneurysm projected in any direction, there was no significant difference in the clipping success rate between the EEA and ipsilateral PA. When the bilateral A2 was in the horizontal position, there was a significant difference in the clipping success rate between the EEA and ipsilateral PA.
The study concluded that the EEA can achieve the same clipping effect as the PA under certain conditions, particularly for small and medium-sized aneurysms that project anteriorly, superiorly, inferiorly, and laterally. However, due to the lower degree of surgical freedom, caution should be exercised when considering the EEA for clipping large aneurysms or those that project posteriorly. The position of the bilateral A2 also influences the effectiveness of the EEA, with horizontal positioning facilitating better outcomes.
This study utilized 3D printed models to provide valuable insights into the anatomical and technical aspects of the EEA and PA for clipping ACoA aneurysms. While the models do not completely mimic real surgical scenarios, they offer a useful platform for pre-operative planning and training. The findings suggest that the EEA is a viable alternative to the PA in selected cases, but further research and clinical trials are needed to establish its broader applicability.
doi.org/10.1097/CM9.0000000000001593
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