✓ Fibrinogen, fibrin monomer, and D dimer were analyzed in 41 cases of chronic subdural hematoma (SDH) to characterize local rebleeding, coagulation, and fibrinolysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Chronic SDH's were divided into five groups according to their appearance on computerized tomography: high-density, isodensity, low-density, mixed-density, and layering types. The concentration of fibrinogen, which indicates rebleeding, was higher in the mixed-density (15.7 ± 3.4 mg/dl (mean ± standard error of the mean)) and layering (15.7 ± 2.6 mg/dl) types of hematoma, and lower in the low-density hematomas (1.4 ± 0.6 mg/dl) compared with the isodense hematomas (6.9 ± 1.1 mg/dl). Fibrin monomer, which indicates coagulative activity, had a distribution similar to that of fibrinogen: 87 ± 22, 18 ± 8, 175 ± 40, and 177 ± 23 µg/ml in isodense, low and mixed-density, and layering types of hematomas, respectively. The D dimer, which indicates fibrinolytic activity, was higher in the layering hematoma type (2032 ± 384 µg/ml), and lower in low-density hematomas (301 ± 164 µg/ml) compared to isodense (1310 ± 256 µg/ml) and mixed-density (1039 ± 207 µg/ml) types of hematomas.
These observations suggest the following characterization of each type of chronic SDH. The layering type is active, with a high tendency to rebleed and for hyperfibrinolytic activity. The mixed-density type has a high tendency to rebleed with lower hyperfibrinolytic activity than the layering type. The low-density hematoma is stable with a low tendency to rebleed and to fibrinolytic activity.