Abstract
We studied changes in the activity of coagulation and fibrinolysis in 2 groups of patients-one with chronic subdural hematomas (CSH's), and the other with minor head injuries and age-related changes in normal subjects. In the first group of 64 patients with CSH's, we measured 4 parameters in hematoma contents : fibrinogen, D -dimer, α-2 plasmin inhibitor (A2PI) and plasmin-α2 plasmin inhibitor complex (PLN-A2PIC). No fibrinogen was detected in any hematoma sample, but in contrast D-dimer appeared in extremely high concentration. A2PI was present within normal values, but PLN-A2PIC showed a tendency to increase. The patients with CSH's were divided radiologically into 4 types, according to their X-ray absorption values in CT images : a high-density type, an isodensity type, a low-density type, and a layering type. In contrast to the CT findings, there was no significant difference in the fibrinolytic factors as measured by PLN-A2PIC and A2PI. From these results, local hyperfibrinolysis was found in the hematoma contents, but analysis of those fibrinolytic factors did not make it possible to evaluate the degree of fibrinolysis. At the time of surgery, we also collected peripheral venous blood to measure fibrinopeptide A (FPA) as an indicator of thrombin activity and fibrinopeptide Bβ 15-42 (FPB) as an indicator of plasmin activity. It was thus found that increased fibrinolytic activity occurred not only in the hematoma contents but also in the systemic blood. Furthermore, in several cases followed up postoperatively, plasma levels of FPB remained above normal, which may reflect persistence of accelerated systemic fibrinolytic activity. In the second group of 56 patients with minor head injuries, the FPA and FPB in venous blood taken within 1 week after injury were both elevated. Out of the 56 cases, 26 cases were followed up for more than 3 weeks after injury, and through CT scan, 11 out of the 26 cases showed subdural fluid collection. Although the cases followed up showed systemic hyperfibrinolysis with or without subdural fluid collection, it was learned that the systemic fibrinolysis was not affected by the presence of subdural fluid collection. Moreover, in one case, it was observed that subdural fluid collection developed into CSH, concurrent with a gradual increase in fibrinolytic activity. It was thus suspected that old people have a tendency of elevated fibrinolytic activity even without head injury. Therefore, in normal subjects, our plan was to examine age-related changes in the plasma levels of FPA and FPB. The plasma level of FPB showed a positive correlation with age, and fibrinolytic activity increase with age. It was thus concluded that systemic hyperfibrinolysis in old people may play an important role as one of the causes of CSH's following minor head injuries and may explain why CSH's are common found in old patients.
