From the Guidelines
Posterior circulation aneurysms, such as those located in the vertebrobasilar system, posterior communicating artery, and basilar tip, have the highest risk of rebleeding in Subarachnoid Hemorrhage (SAH) patients. The risk of rebleeding is a critical concern in the management of SAH, as it can lead to significant morbidity and mortality. According to a study published in 2020 1, factors associated with rebleeding include temporal proximity to the first hemorrhage, higher blood pressure, worse neurological grade, intraventricular or intracerebral hemorrhage, and larger aneurysm. The study also found that posterior circulation aneurysms are associated with an increased risk of rebleeding.
The guidelines for the management of aneurysmal subarachnoid hemorrhage, published in 2012 1, recommend urgent evaluation and treatment of patients with suspected aSAH, as the risk of early aneurysm rebleeding is high and associated with very poor outcomes. The guidelines also suggest that surgical clipping or endovascular coiling of the ruptured aneurysm should be performed as early as feasible in the majority of patients to reduce the rate of rebleeding after aSAH.
Key factors that contribute to the increased risk of rebleeding in posterior circulation aneurysms include:
- Deeper location
- Thinner vessel walls
- Higher hemodynamic stress
- More complex morphology
- Irregular shapes, multiple lobes, or daughter sacs that create areas of wall weakness
- Higher pulsatile blood flow pressures
For SAH patients with identified posterior circulation aneurysms, urgent intervention (within 24-48 hours) through either surgical clipping or endovascular coiling is strongly recommended to prevent the catastrophic consequences of rebleeding, which carries a mortality rate of up to 70% 1.
From the Research
Risk of Rebleeding in SAH
The risk of rebleeding in Subarachnoid Hemorrhage (SAH) patients is a critical concern. Several factors can influence this risk, including the type of aneurysm, its location, and the patient's clinical condition.
Factors Associated with Rebleeding
- The location of the aneurysm is a significant factor, with aneurysms in the anterior communicating artery being more prone to rebleeding 2.
- The size of the aneurysm, deterioration of neurologic deficits, angiography within 3 hours of bleeding, sentinel symptoms, and the loss of consciousness at initial bleeding are also potential risk factors for rebleeding 3.
- High systolic blood pressure, sentinel headache, initial loss of consciousness, poor Hunt and Hess grade, high Fisher grade on initial CT, and large aneurysm size are additional factors that may increase the risk of rebleeding 3.
Type of Aneurysm with the Highest Risk of Rebleeding
- Anterior communicating artery aneurysms have been identified as having a higher risk of rebleeding compared to other types of aneurysms 2.
- The study by 2 found that male gender and location of aneurysm (anterior communicating artery) were statistically significant between rebleeding group and non-rebleeding group.
Treatment Options and Rebleeding Risk
- Endovascular coiling and neurosurgical clipping are two common treatment options for aneurysmal SAH, with coiling being associated with a better outcome in patients with ruptured aneurysms of either the anterior or posterior circulation 4, 5.
- However, the risk of rebleeding is higher with endovascular coiling compared to neurosurgical clipping, with a risk ratio of 1.83 at one year and 2.69 at 10 years 5.