Safety of early warfarin resumption following burr hole drainage for warfarin-associated subacute or chronic subdural hemorrhage.

The primary objective of this study was to evaluate the safety of early warfarin resumption following burr hole drainage for warfarin-associated subdural hemorrhage (SDH). This prospective, single-arm, single-center trial was conducted from February 2008 to April 2010. Inclusion criteria were premorbid warfarin therapy, subacute or chronic SDH requiring burr hole drainage, and an International Normalized Ratio (INR) of >1.5 at presentation. Three days after surgery, warfarin was re-administered to reach the target INR range of 1.7-2.5. Patients were followed by regular INR monitoring and serial brain CT scans, which were performed at 1 week, and at 1, 3, and 6 months after surgery. The primary outcome was recurrent SDH incidence. Twenty patients were enrolled and CT scans performed at 1 week revealed no new intracranial hemorrhage in any patient. Subsequent scans were performed at 1 month on 19 patients, and recurrent SDH was observed in three. However, this recurrence rate (15.8%; 95% CI 0,34) did not exceed that of ordinary SDHs, and all recurrent SDHs were successfully managed by repeated burr hole drainage. The other 16 patients completed their 6-month follow-ups uneventfully. SDH recurrence was found to be associated with older age (≥ 75 years), and a thicker SDH (≥ 25 mm), but not with post-operative anticoagulation status. None of the study subjects experienced a thromboembolic event during the study period. Restarting warfarin therapy does not need to be withheld for more than 3 days after burr hole drainage, particularly in patients with a high thromboembolic risk.