Delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a narrative review

Aneurismal subarachnoid hemorrhage (aSAH) is a condition with elevated mortality and morbidity, which usually affects a working-age population, leading to a high socioeconomic burden. Among those who survive the initial bleeding, approximately 30% will experience delayed cerebral ischemia (DCI), which is a significant factor in poor outcomes. However, it is potentially reversible if appropriate treatment is promptly initiated. The amount of blood present on the initial computed tomography (CT) scan, assessed through the modified Fisher scale (mFisher), and the patient's neurological status upon admission, are the strongest predictors of DCI. Early prevention is essential and typically involves administration of enteral nimodipine and the maintenance of euvolemia, while other treatment options have limited supporting evidence. Diagnosing remains a challenge, primarily due to its reliance on clinical examinations. This is more pronounced in high-grade aSAH patients who are unconscious or sedated. In such cases, additional methods may be necessary, such as transcranial Doppler (TCD), continuous electroencephalography (cEEG), or CT with perfusion (CTP). Treatment aims to prevent cerebral infarction and poor clinical outcomes, and it is based on hemodynamic optimization, hypertension induction, cardiac output augmentation, and endovascular therapy. Nevertheless, randomized data on DCI management remains scarce, highlighting the urgent need for more studies and a better understanding of this SAH complication. Addressing this gap may lead to more effective preventive strategies and treatments, which is crucial for improving the prognosis of these patients.