PLAUR and hematoma: We hypothesized that [1] uPAR is present in hematoma fluid, hematoma membrane, dura mater, and systemic blood from CSDH patients due to similar biological features in both CSDH disease and uPAR, [2] uPAR levels predict CSDH recurrence in patients with primary CSDH, as patients later developing a recurrent CSDH presumably hold a higher level of inflammation, angiogenesis and/or fibrinolysis, and [3] uPAR is elevated at the time of the second operation in patients with recurrent CSDH due to an increasing involvement of either of the three pathophysiological processes.