To the Editor:—

We wish to alert our colleagues about the danger of performing epidural injections in patients who are receiving several antiplatelet drugs. A patient with acute onset of quadriparesis was referred to our hospital with a large cervical epidural hematoma. He developed numbness and weakness of his arms and legs within 30 min after the performance of a cervical epidural steroid injection. At the time of injection, he was taking several antiplatelet drugs (diclofenac, clopidogrel, and possibly aspirin) that had been started after a prior coronary angioplasty. He had a prior uneventful cervical epidural steroid injection 11 days before the incident in question, but it is not clear if he was taking these antiplatelet drugs then. The patient had no history of easy bruisability. His prothrombin time, international normalized ratio, and partial thromboplastin time were within normal limits, and his platelet count was 160,000/μl but the timing of the last doses of antiplatelet drugs was unclear. He underwent an emergency C3–T3 laminectomy and evacuation of cervical epidural hematoma, which extended from the C2 to C7 vertebral levels, approximately 14 h after the epidural injection. Postoperatively, the strength in the patient's upper extremities improved, but his lower extremities remained paralyzed. Three months after surgery, he had regained his strength in his upper extremities, but the paralysis of his lower extremities remained.

The relative safety of epidural injections in patients on antiplatelet drugs has been established. 1In the rare case reports of spinal hematoma involving antiplatelet drugs, some complicating factors were present: concomitant heparin administration, 2epidural venous angioma, 2repeated epidural injections, 3and technical difficulties in performing the injection. 4–6The latter factor has been suggested as major risk factor in the development of spinal hematoma. 1,5–8 

The thienopyridine derivatives ticlopidine and clopidogrel represent a newer class of antiplatelet drugs with antiplatelet mechanisms different from that of aspirin. These drugs inhibit induced platelet aggregation, possibly by altering platelet membrane and blocking the interaction between fibrinogen and the membrane glycoprotein receptor, GPIIb/IIIa. 9–11Clopidogrel and ticlopidine also seem to modulate vascular smooth muscle, resulting in reduced vascular contraction. 12These drugs inhibit platelet adhesion to the vascular endothelium and shear stress-induced platelet aggregation and secretion. 13Clopidogrel is 40–100 times more potent than ticlopidine. 14After discontinuation of clopidogrel therapy, platelet aggregation and bleeding time return to baseline within 5 days. Although there has been no case report of spinal hematoma after a neuraxial block in patients receiving clopidogrel alone, there has been a case of spinal hematoma in a patient on ticlopidine. 6 

The drug package literature for clopidogrel cautions its use with aspirin, warfarin, or nonsteroidal antiinflammatory drugs that have different, and possibly additive, antiplatelet mechanisms.* Despite the lack of data on the effect of combination of these drugs on duration of antiplatelet inhibition, we recommend that neuraxial blocks be postponed for 5–7 days in patients who are receiving several antiplatelet drugs.

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