ANTICOAGULATION AND NEURAXIAL ANESTHESIA

Abstract

Spinal hematoma is a rare and potentially catastrophic complication of spinal or epidural anesthesia. The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with central neural blockade is unknown; however, the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthetics. 39 Hemorrhage into the spinal canal most commonly occurs in the epidural space because of the prominent epidural venous plexus. Although hemorrhagic complications can occur after virtually all regional anesthetic techniques, bleeding into the spinal canal is perhaps the most serious hemorrhagic complication associated with regional anesthesia because the spinal canal is a concealed and nonexpandable space. Spinal cord compression from spinal hematoma may result in neurologic ischemia and paraplegia. Spinal hematoma may occur from vascular trauma from needle or catheter placement into the subarachnoid or epidural space. However, it may also occur in association with neoplastic disease or preexisting vascular abnormalities. Of special interest to the anesthesiologist are those spinal hematomas that have occurred spontaneously with or without the presence of antiplatelet or anticoagulation therapy. Over 100 spontaneous epidural hematomas have been reported, 25% of which are associated with anticoagulation therapy. 38 In a review of the literature between 1906 and 1994, Vandermeulen et al 41 reported 61 cases of spinal hematoma associated with epidural or spinal anesthesia. In 42 of the 61 patients (69%), the spinal hematomas associated with central neural blockade occurred in patients with evidence of hemostatic abnormality. Twenty-five of the patients had received intravenous or subcutaneous heparin, while an additional five patients were presumably administered heparin as they were undergoing a vascular surgical procedure. In addition, 12 patients had evidence of coagulopathy or thrombocytopenia or were treated with antiplatelet medications (aspirin, indomethacin, ticlopidine), oral anticoagulants (phenprocoumone), thrombolytics (urokinase), or dextran. Seventy were treated immediately before or after the spinal or epidural anesthetic. Needle and catheter placement were reported to be difficult or bloody in 15 (25%) patients. Thus, in 53 of the 61 cases (87%), either a clotting abnormality or needle placement difficulty was present. Neurologic compromise presented as progression of sensory of motor block or bowel/bladder dysfunction, not severe radicular back pain. Importantly, although only 48% of patients had partial or good neurologic recovery, spinal cord ischemia tended to be reversible in patients who underwent laminectomy within 8 hours of onset of neurologic dysfunction (Table 1) . In order to reduce the risk of spinal hematoma associated with central neural blockade, it is necessary to understand the mechanisms of blood coagulation, the pharmacologic properties of the anticoagulant and antiplatelet medications, and also the clinical studies involving patients undergoing central neural blockade while receiving these medications. Recommendations for regional anesthetic management follow the consensus statements on Neuraxial Anesthesia and Anticoagulation published by the American Society of Regional Anesthesia. 9 , 18 , 21 , 34 , 40 Although this article will deal mainly with continuous techniques of major conduction blocks and anticoagulants, the same principles apply to all regional anesthetic techniques.