Abstract
BACKGROUND: Chronic subdural haematoma (CSDH) is a common neurosurgical condition with an increasing incidence due to an aging population. Given the expanding research landscape, assessing the state of recent trials is essential. This systematic review updates a previous review, which included randomised controlled trials (RCTs) up to 2019, by summarizing recently published and ongoing RCTs in CSDH, highlighting key areas of investigation and identifying directions for future research. METHODS: Clinical trial registries - including the Cochrane Controlled Register of Trials, WHO ICTRP, clinicaltrials.gov, and Clinical Trials Information System - were systematically searched for RCTs on CSDH from June 1, 2019, to February 18, 2025. Both published and ongoing trials were included in this review. RESULTS: This review identified 41 recently published RCTs and 54 ongoing RCTs, compared to 26 ongoing trials in 2019. Of the earlier review, eleven studies have been published, five remain active, and the remainder were either abandoned or did not adhere to their initial RCT design. Middle meningeal artery embolisation (MMAE) has become the most extensively studied intervention, with active trials increasing from 2 in 2019 to 21 in 2025. Trials investigating perioperative management (3 versus 7) and surgical techniques (5 versus 10) have also increased. In contrast, corticosteroid trials have decreased (7 versus 3), likely reflecting findings from recent high-impact studies. Research on tranexamic acid has increased (5 versus 7) as have studies on other pharmacological agents (4 versus 8). CONCLUSIONS: The number of ongoing RCTs in CSDH has increased substantially, with a notable shift in research focus. MMAE now dominates the field, though the surge in studies may suggest research saturation. Future investigations may benefit from more collaborative efforts, consolidating resources into fewer, but larger and adequately powered trials.