Source of fibrin/fibrinogen degradation products in the CSF after subarachnoid hemorrhage.

In 48 patients with a subarachnoid hemorrhage, levels of fibrin/fibrinogen degradation products (FDP's), total protein, and plasminogen were measured in the cerebrospinal fluid (CSF) between Days 9 and 15 after the bleed. Of these 48 patients, 22 received tranexamic acid. Despite a significant reduction in the incidence of rebleeding in patients taking tranexamic acid, no difference in FDP levels was found between patients receiving tranexamic acid and a control group of patients who were not; nor was any relationship evident between FDP levels and rebleeding. In patients with detectable levels of FDP's, CSF protein and plasminogen values were also increased, and FDP's were found more frequently in the CSF of patients with an impaired level of consciousness or with a neurological deficit. These findings suggest that in the 2nd week after subarachnoid hemorrhage, the presence of FDP's in the CSF reflects a damaged blood-CSF barrier rather than ongoing local fibrinolysis in the subarachnoid space. A finding of FDP's in the CSF is, therefore, an unreliable monitor of antifibrinolytic treatment in subarachnoid hemorrhage and cannot be used for selecting patients at high risk of rebleeding.