[The relationship between coagulation time and bilateral occurrence in chronic subdural hematoma].

The relationship between the bilateral occurrence and coagulation time was analyzed in 137 cases of chronic subdural hematoma. Bilateral chronic subdural hematomas more frequently happened in the patient with coagulation time elongation beyond the normal control. This tendency was significant in the non-traumatic group and bilateral subdural hematomas were found in: 45% in prothrombin time (PT)-elongated group vs 10.3% in non-elongated group and 38.9% in activated partial thromboplastin time (aPTT)-elongated group vs 14.6% in non-elongated group. The ratio of PT and aPTT coagulation time against the normal control was significantly larger in the bilateral group than in the unilateral group. The ratio was as follows: PT ratio was 1.056 in bilateral group and 0.995 in unilateral group. aPTT ratio was 1.051 in bilateral group and 0.954 in unilateral group. Furthermore the bilateral hematomas tended to happen in hemodialysis cases, and in patients on warfarin or anti-platelet drugs. Bilateral hematomas were found in 41.7%, 37.5% and 33.3% respectively. The ratio of PT and aPTT coagulation time was as follows: PT ratio was 1.040 in hemodialysis cases and 1.082 in warfarin-applicated cases. aPTT ratio was 1.022 in hemodialysis cases and 1.055 in warfarin-applicated cases. These results suggest that the suppressed coagulation ability and platelet function are involved in the genesis of bilateral chronic subdural hematomas.