Etiology of Chronic Subdural Hematoma

—Role of Local Hyperfibrinolysis—

Abstract

Local fibrinolytic activity is studied to explain the physiopathogenesis of chronic subdural hematoma.
1. Using FDP-kit (Wellcome, England), FDP levels in hematoma fluid and serum are determined in 15 cases with unilateral hematoma and a case with bilateral hematoma. The FDP values in all hematomas are higher than 20 μg/ml. Two cases show the FDP values over than 320 μg/ml. The FDP values in hematoma fluid is always higher than that in serum of the same patient. The FDP values in hematoma fluid correlate to the volume of hematoma in fluid type subdural hematomas.
2. The levels of fibrinolytic activity in hematoma fluid and plasma are determined in 12 cases with subdural hematoma by Enzo-diffusion fibrin plate (Hyland, U.S.A.). Active plasmin, available plasmin and total plasminogen in hematoma fluid are not found in all cases with subdural hematoma. The fibrinolytic activity in hematoma fluid is remarkably lower than that in plasma in all cases. Absence of plasminogen might be for consumption.
3. The amounts of tissue active plasmin in 7 cases and tissue plasminogen activator in 8 cases are measured by modified Astrup's method.
Tissue active plasmin levels in dura maters, outer membranes and inner membranes are 3.7-7.2 mm (average 6.1 mm), 4.3-6.5 mm (5.5 mm) and 0-4.8 mm (1.7 mm), respectively.
Tissue plasminogen activator levels in dura maters, outer membranes and inner membranes are 0-5.5 mm (average 2.7 mm), 3.3-8.1 mm (6.1 mm) and 0 mm, respectively. The tissue activator level is highest in the outer membrane.
4. Fibrinolysis autography by Todd's method demonstrates the remarkable fibrinolysis around the vessels of outer membrane. The fibrinolysis in tissue increases with time.
5. After clotting of subdural hemorrhage, capsule (grows out) from the dura mater. Then tissue plasminogen activator in outer membrane would activate fibrinolytic system in order to absorb subdural clot. If the fibrinolytic activity is adequate, the clot could be absorbed. If the fibrinolytic activity is excess, it would inhibit the coagulating system in vessels of outer membrane and so that the continual or intermittent bleeding from outer membrane would occur into subdural cavity. As the result, the FDP levels in hematoma fluid increase and the amounts of plasminogen decrease for consumption. Such fibrinolytic bleeding from outer membrane of hematoma induces gradually the enlargement of hematoma and clinical symptoms appear after a latent interval.