An aneurysmal subarachnoid hemorrhage (aSAH) is a severe form of brain hemorrhage that occurs when an aneurysm – a weakened area in a blood vessel in the brain – bursts. This causes blood to leak into the fluid surrounding the brain, which is called cerebrospinal fluid (CSF). The breakdown products of this blood can be harmful to the brain and lead to vasospasm, a condition in which the brain's blood vessels contract inappropriately. Vasospasm can severely obstruct the blood flow to the brain, potentially resulting in stroke, paralysis, or even death. This master’s thesis investigates the role of CSF drainage, where CSF is removed from around the brain and spinal cord, as a preventive measure against vasospasm following aSAH. It compares the effectiveness of two drainage methods: external ventricular drainage (EVD), where a catheter is placed in the brain, and lumbar drainage (LD), where a catheter is inserted through the lower back. The study is conducted to explore a potential new approach: rinsing of CSF. In this method, a flushing solution would be introduced via the EVD and drained through the LD, aiming to accelerate the removal of blood and its harmful breakdown products from the brain and CSF. This could potentially reduce vasospasms and improve patient prognosis. The results of the study show that both EVD and LD are effective in reducing vasospasm compared to no drainage. Some researchers prefer lumbar drainage, as it promotes the normal production and circulation of CSF, facilitating the removal of bloody CSF and potentially resulting in fewer complications. However, this preference is not yet sufficiently supported by prospective randomized studies, meaning that no definitive recommendation can be made. Given that aSAH predominantly affects middle-aged individuals and vasospasm can have severe consequences, it is crucial to improve treatment methods. While draining bloody CSF has already improved patient prognosis, the loss of healthy life years remains a significant issue. By further preventing vasospasms, we hope to improve quality of life by reducing severe complications such as paralysis and strokes, and lowering the number of fatalities. The societal value of this research is considerable. It can contribute to the improvement of treatment methods, which not only enhances patients' quality of life but also reduces the risk of neurological damage, disability, or death. This increases the chances of recovery, allowing patients to live longer and healthier lives. Additionally, the patient's environment benefits from faster recovery, as this reduces the caregiving burden on family members and society. Furthermore, the research offers benefits for the healthcare system. Improving the prevention of vasospasm can enhance the effectiveness of aSAH treatments, leading to better patient outcomes and higher quality of care. Fewer complications mean that patients are less likely to require prolonged hospital stays or intensive rehabilitation, potentially leading to significant cost savings. It could also alleviate the pressure on healthcare facilities and bring about economic benefits, such as a faster return to work for patients, promoting work reintegration and reducing unemployment benefits. Preventing death helps maintain productive workers, contributing to economic stability. In summary, the societal impact of this research lies in the potential improvement of treatment protocols for aSAH patients, which could lead to better health outcomes, less (severe) complications, cost savings, and an enhanced quality of life for both patients and the broader community.