PLAUR and hematoma: By investigating the role of uPAR in CSDH, we aimed to [1] identify uPAR in the hematoma fluid, hematoma membrane, dura mater, and systemic blood, [2] investigate if the level of uPAR at the time of surgery for first-time CSDH may predict recurrence, and [3] examine if uPAR expression is different between the first and second operations in patients with recurrent CSDH.