What are the Causative Factors for a Slow, Progressive Enlargement of a Chronic Subdural Hematoma?

PURPOSE: To test the hypothesis that chronic subdural hematoma (CSDH) enlarges by the causative factors, this study has performed. MATERIALS AND METHODS: In 10 patients with CSDH, coagulation factors in venous blood taken at the time of surgery and hematomic contents aspirated from the CSDH were studied, using both laboratory assays and microscopy. RESULTS: When compared to the range of normal plasma, the hematoma fluids demonstrated a marked reduction in factor II, V, VII, VIII, and X, moderate reduction of factors IX and XI, and slight reduction of factor XII. Activated protein C and antithrombin III levels were decreased. The FDP (Fibrinogen Degradation Product) levels in chronic subdural hematoma were extremely high. The endothelial cells of the macrocapillaries (also called "sinusoid") showed numerous gap junctions between adjacent endothelial cells and a thinness or absence of the basement membrane, suggesting that the macrocapillaries are very fragile and susceptible to bleeding. CONCLUSION: Excessive coagulation in the hematoma, predominantly via the extrinsic clotting pathway, local hyperfibrinolysis, transmitted pulsations, and characteristics of the macrocapillaries play an important role in the leakage of blood and the enlargement of CSDH.