A Study on the Safety of Tranexamic Acid for the Chronic Subdural Hematoma Population

Chronic subdural hematomas are a common problem faced by neurosurgery with an annual incidence of 13.5/100,00 persons per year and up to 58/100,000 in the over 65 years old population. Their treatment is often complicated by recurrence with rates reported as high as 33%. Currently there is no good strategy to help avoid this problem, which adds significantly to patient morbidity. The pathogenesis of this problem is believed to be related to the propensity of the associated neo-membranes to bleed. It has been shown with labeled red blood cells that bleeding continues to occur into the hematoma cavity. It has also been shown that there are high levels of tissue plasminogen activator in the outer membrane of chronic subdural hematomas. It has been found that ratio of tissue plasminogen activator to plasminogen activator inhibitor contributed to the pathogenesis. It has also been shown that chronic subdural hematomas have high levels of fibrin degradation products which in addition to marking the breakdown of fibrin are themselves antihemostatic by enhancing tissue plasminogen activator activity, having an antithrombin affect and inhibiting platelet aggregation and fibrin polymerization. Essentially, a scenario of ongoing hemorrhage and repeated clot formation and hyperfibrinolysis leads to the expansion and recurrence of chronic subdural hematomas.

Given the importance of plasmin and hyperfibrinolysis in the pathophysiology of chronic subdural hematomas, interrupting its action and the vicious cycle it propagates seems an ideal therapeutic target. Tranexamic acid is a synthetic lysine amino acid derivative. It binds to the fibrin binding sites on plasmin or plasminogen and prevents its interaction and degradation of fibrin. This effect on the neo-membranes of chronic subdural hematomas should prevent rebleeding and the reaccumulation of the subdural hematoma.

Tranexamic acid has been shown to be safe and effective in reducing blood loss and transfusions in a number of types of surgery, reduced mortality and need for urgent surgery in patients with GI bleeding, and reduced bleeding associated with menorrhagia and pregnancy. Adverse effects are generally mild. Thought there is a theoretical increased risk of thromboembolic complications, multiple randomized controlled trials have not shown an increased risk. Furthermore, in a study of over 3000 gynecologic patients using tranexamic acid, there were no thromboembolic complications. This is likely because tranexamic acid has been shown to not have an effect on plasminogen in the vein wall.