Subarachnoid hemorrhage (SAH) is a life-threatening condition that occurs due to the extravasation of blood between the pial and arachnoid membranes, commonly caused by the rupture of a cerebral aneurysm or a traumatic head injury, leading to the accumulation of blood between these two layers [1]. Almost 85% of nontraumatic subarachnoid hemorrhage cases are attributed to the rupture of a intracranial aneurysm, with almost half of patients presenting with this condition dying within 30 days, and a third of the survivors experiencing complications [2], [3]. According to a recent worldwide meta-analysis, the overall crude incidence of aneurysmal subarachnoid hemorrhage (aSAH) was estimated to be 7.9 per 100,000 person-years, with a slightly higher risk of aSAH occurrence observed in women compared to men, as indicated by the risk ratio of 1.3 [4]. Angiographic cerebral vasospasm (CVS) transpires in approximately 70% of patients in the initial 14 days subsequent to aSAH, although the frequency of delayed cerebral ischemia (DCI) is approximately 30% [5]. Aneurysm rebleeding, which has a mortality rate of 20–60%, is associated with poor clinical grades, larger aneurysms, and hypertension [6]. Both DCI and rebleeding are the primary culprits of morbidity and mortality among those who endure the initial management of the ruptured aneurysm.

The management of aneurysms involves several approaches, including observation, medical management, and surgical intervention. The two main surgical techniques are endovascular coiling and microsurgical clipping [7]. Endovascular coiling is a minimally invasive technique for treating cerebral aneurysms by inserting metal coils into the aneurysm sac to block the flow of blood [8]. Microsurgical clipping is a more invasive technique for treating cerebral aneurysms by placing a small metal clip across the base of the aneurysm, effectively sealing it off from the rest of the blood vessels in the brain. Research studies that looked at randomized clinical trials and observational trials have shown that using coiling to treat a ruptured aneurysm in patients with aSAH leads to better outcomes and lower mortality rates compared to using clipping [9], [10], [11]. Following these trials, coiling has gradually replaced clipping in several centers and is being regarded as the preferred first-line treatment in some countries or centers [12]. The trials have a strong internal validity, but the external validity is questionable due to several factors. Firstly, most of the studies used in the analysis were cohort studies which may not always provide the most reliable results due to potential biases in data collection and analysis. It is worth noting that cross-sectional and case-control studies are generally not as reliable as other types of studies and combining them may decrease the validity of the conclusions drawn from the trials. Secondly, the primary outcomes used in the trials were limited to individual measures, while they should have included a combination of factors. For instance, for assessing the effectiveness of treatment, the outcomes should have comprised of mortality, morbidity, and complete occlusion. On the other hand, for evaluating the safety of the treatment, the outcomes should have included vasospasm, rebleeding, post-operative complications, and cerebral ischemia [13]. Thirdly, certain RCTs were not included in some of the studies. The selection of an appropriate intervention for managing a ruptured intracranial aneurysm, such as microsurgical clipping or endovascular treatment, should be based on a thorough consideration of several crucial factors, including but not limited to the size, location, and configuration of the aneurysm, as well as the patient's age, comorbidities, and individual preferences [14].

This study holds considerable importance as it provides a comprehensive evaluation of the two predominant treatment options for aneurysmal subarachnoid hemorrhage. Forecasting the outcome of both approaches to aSAH can be challenging owing to differences in patient features, clinical progress, and aneurysm morphology [15]. Clinical prediction models, which statistically combine the effectiveness and safety profiles to estimate the probability of outcome, can be a dependable evidence-based resource for decision-making and guiding expectations regarding the outcome.

In the context of an evolving landscape of endovascular treatments for aSAH, this systematic review and meta-analysis comprehensively assesses the historical debate between microsurgical clipping and endovascular coiling. While acknowledging the changing dynamics in aSAH management, we aim to provide insights into the efficacy and safety of these interventions. Our study recognizes the individualized approach to aSAH treatment and the continuous advancement of endovascular technologies, thereby bridging the historical context with present developments.