We report a case of an asymptomatic spinal epidural hematoma (SEH) after epidural anesthesia that was detected by a second lumbar epidural puncture when the patient presented for a second vascular procedure.
A 75-yr-old, 60-kg man presented with left foot ischemic pain. His past medical history was significant for a previous aortobifemoral bypass, old myocardial infarction, renal insufficiency, and a cerebrovascular accident with residual left lower extremity weakness. Medications included pentoxifyl-line 400 mg three times a day and one coated aspirin (ASA) daily. Laboratory examination was remarkable for blood urea nitrogen levels of 98 mg/dL and creatinine levels 1.7 mg/dL. Prothrombin time, partial thromboplastin time, and platelet count were within normal limits. Arteriography revealed arterial occlusive disease at the level of the popliteal artery trifurcation. The patient was taken to the operating room for a femoral-distal bypass to the posterior tibial artery under epidural anesthesia. Epidural puncture using a loss of resistance to saline technique was performed without difficulty at the L3-4 interspace with an 18-gauge Tuohy needle by an experienced anesthesiologist. Aspiration for blood and cerebrospinal fluid was negative. Aspiration of an epidural catheter placed through the Tuohy needle 3 cm into the epidural space was also negative. Five hours later, 5000 units of heparin was administered intravenously. Protamine reversal of the heparin was not administered . Dextran 40, 100 mg, was administered, and a continuous infusion of 20 mL/h was begun 7 h after epidural placement and continued for 72 h. The epidural catheter remained in place for 24 h postoperatively for pain management. ASA therapy was resumed on Postoperative Day 1.
Coagulation variables were within normal limits at the time of removal of the epidural catheter. The patient remained neurologically intact and did not complain of back or radicular pain, paresthesia, or urinary retention. On the 10th postoperative day, he again complained of left foot pain. Repeat arteriography revealed flow-limiting stenosis above the distal anastomosis. The patient was brought to the operating room for revision of the stenotic graft. An epidural anesthetic was once again planned. Coagulation variables were within normal limits. When an 18-gauge Tuohy needle was inserted at the L3-4 level, black, tarry, liquefied blood returned under pressure from the epidural space. After removal of approximately 10 mL of old blood, no additional blood returned passively or with gentle aspiration. The needle was withdrawn, and the anesthetic technique was converted to a spinal anesthetic at the L2-3 interspace. The surgery proceeded uneventfully. Computerized tomography (CT) without contrast was performed postoperatively. The CT scan was equivocal for the presence of epidural hematoma. Subsequent magnetic resonance imaging (MRI) revealed epidural hematoma at interspace L2-4. The patient remained neurologically intact and was discharged on the sixth postoperative day.
Asymptomatic SEH is a rare incidental finding at autopsy or laminectomy [2-11]. The diagnosis of SEH is usually made from the clinical presentation and radiographic imaging. SEH detected during lumbar epidural puncture has not been previously reported. In our patient, there was no clinical suspicion of SEH, and the diagnosis was not considered until a liquefied clot was evacuated from the epidural space at the time of repeat lumbar epidural puncture.
Spinal epidural hematoma may have a spontaneous, traumatic, idiopathic, or iatrogenic origin (Table 1) [12-26]. Compressive SEH with associated neurological deficits is more likely to occur within the cervical or thoracic spinal canal, as the spinal cord occupies a greater percentage of the canal diameter in this region [12,26]. Our case illustrates the ability of the lumbar epidural space below L2 to accommodate hemorrhage without producing neurologic symptoms. With the spinal cord normally terminating opposite to the L1-2 disc space, compressive SEH within the lumbar spinal canal below that level can cause a cauda equina syndrome. Injury to the cauda equina can present with back pain progressing to sensory changes, motor weakness, and bowel and bladder deficits . It is believed that cauda equina injuries have a better prognosis for neurological recovery than upper spinal levels, but permanent motor and sensory loss can occur if SEH is left untreated [27,28].
The incidence of SEH in a large case series of 850,000 patients after central neuroaxial blockade (CNB) is estimated to be 1:150,000 , although that review does not specify whether these patients received anticoagulant therapy. The safe use of epidural anesthesia during anticoagulant therapy has been documented in reports over the past 15 years [30,31]. However, in reviews of published cases of SEH involving a CNB technique, the most constant risk factor identified in 60%-80% of patients was impaired coagulation at the time of initiation of CNB or epidural catheter removal [30,31]. We chose epidural anesthesia for our patient because of his medical history and to facilitate postoperative pain management. Our patient received ASA therapy prior to initiation of the first epidural anesthetic and a dextran infusion at the time of withdrawal of the epidural catheter. Considered independently, the incidence of SEH after CNB during either ASA or dextran therapy is very low [31-35]. In our case, the combination of ASA therapy, heparinization, and dextran therapy may have increased the risk of SEH after epidural anesthesia. Conceivably, our patient's chronic renal insufficiency may have resulted in abnormal platelet function, further contributing to this risk.
Several factors were considered prior to performing a spinal anesthetic for the second operative procedure after a resolving clot was detected during a lumbar epidural puncture. The patient was asymptomatic prior to evacuating the liquefied clot within the epidural space, and perioperative anticoagulation was not anticipated. Furthermore, the greatest risk of producing bleeding into the epidural space occurred at the time of epidural puncture rather than during the less traumatic subarachnoid puncture . Postoperative radiographic imaging confirmed that these procedures did not produce acute hemorrhage within the epidural space.
Evidence of the liquefied clot during the lumbar epidural puncture prompted us to seek a radiographic diagnosis. The superiority of MRI in the diagnosis of subacute spinal epidural hematoma compared with CT imaging was evident in this case. Because of its multiplanar imaging capability and its ability to date hematomas by the unique magnetic resonance signal characteristics of various ages of hemorrhage, MRI allows a more specific diagnosis of spinal hematomas [36-39]. CT was chosen as the initial imaging method because MRI was unavailable. Axial CT images from L2-3 through L4-5 did not convincingly demonstrate the epidural hematoma, even in retrospect. Since the hematoma was not acute when imaged with CT, the blood no longer appeared dense (white), which diminished its conspicuity (Figure 1). Axial (Figure 2) and parasagittal MRI images revealed increased signal intensity on both T1- (Figure 3a) and T2- (Figure 3b) weighted images within the dorsal epidural compartment from L2 through L4, consistent with an epidural hematoma. A normal MRI image (Figure 4) is included for comparison. The increased signal intensity on both T1- and T2-weighted images is consistent with subacute hematoma [26,36], as was suggested by the appearance of the liquefied clot evacuated from the epidural space and the history of a previous lumbar epidural puncture 10 days prior to MRI. In contrast, acute hemorrhage (between 24 and 72 hours) is usually heterogeneously hypointense on weighted images . Intravenous administration of gadopentetate dimeglumine (gadolinium) is useful in the evaluation of spinal tumor or infection but is not necessary for the detection of spinal canal hemorrhage  and was not administered in this case.
We chose observant management for this patient with an SEH at the L2-4 region because of the absence of neurological dysfunction and its location below the termination of the spinal cord. When the diagnosis of SEH is made or strongly suspected, immediate neurosurgical consultation should be obtained. An emergent MRI scan followed by surgical evacuation of the SEH is recommended for those patients with a neurological deficit. Neurological recovery is related to the severity of preoperative deficits and the rapidity of surgical decompression . The neurosurgical consultant can assist in determining the most appropriate treatment for the neurologically intact patient with a SEH below the level of termination of the spinal cord based on the size and nature of the hematoma.
This case demonstrates several important points: 1) epidural hematomas may be asymptomatic and may occur more often than is realized, 2) MRI is the diagnostic modality of choice, and 3) conservative therapy is effective in patients without neurological deficits.
1. Dorman BH, Elliott BM, Spinale FG, et al. Protamine use during peripheral vascular surgery: a prospective randomized trial. J Vasc Surg 1995;22:248-56.
2. Barker GL. Spinal subdural hematoma following spinal anaesthesia. Anaesthesia 1988;43:664-5.
3. Gustafsson A, Ruthberg H, Bengtsson M. Spinal haematoma following epidural analgesia. Anaesthesia 1988;43:220-2.
4. Gordh R, Mostert JW. The neurological sequelae of anesthesia (cases 48-60). Int Anesthesiol Clin 1978;16:115-85.
5. Bromage PR. Complication and contraindications. In: Bromage PR, ed. Epidural analgesia. Philadelphia: WB Saunders, 1978:654-715.
6. Usubiaga JE. Neurological complications following epidural anesthesia. Int Anesthesiol Clin 1975;13:1-157.
7. Wille-Jorgensen P, Jorgensen LN, Rasmussen LS. Lumbar regional anaesthesia and prophylactic anticoagulant therapy. Anaesthesia 1991;46:623-7.
8. Eastwood DW. Hematoma after epidural anesthesia: relationship of skin and spinal angiomas. Anesth Analg 1991;73:352-4.
9. Swerdlow M. Medico-legal aspects of complications following pain relieving blocks. Pain 1982;13:321-31.
10. Digiovanni J. Case history, number 70 [discussion]. Anesth Analg 1973;52:71-2.
11. Gingrich TF. Spinal epidural hematoma following continuous epidural anesthesia. Anesthesiology 1968;29:162-3.
12. Mattle H, Sieb JP, Rohner M, Mumenthaler M. Nontraumatic spinal epidural and subdural hematomas. Neurology 1987;37:1351-6.
13. Lawton MT, Porter RW, Heiserman JE, et al. Surgical management of spinal epidural hematoma: relationship between surgical timing and neurological outcome. J Neurosurg 1995;83:1-7.
14. Mohazab HR, Langer B, Spigos D. Spinal epidural hematoma in a patient with lupus coagulopathy: MR findings. AJR AM J Roentgenol 1993;160:853-4.
15. Hurst PG, Seeger J, Carter P, Marcus FI. Value of magnetic resonance imaging for diagnosis of cervical epidural hematoma associated with anticoagulation after cardiac valve replacement. Am J Cardiol 1989;63:1016-7.
16. Licata C, Zoppetti MC, Perini SS, et al. Spontaneous spinal haematomas. Acta Neurochir (Wien) 1988;95:126-30.
17. Garth WP, Van Patten PK. Fractures of the lumbar lamina with epidural hematoma simulating herniation of a disc. J Bone Joint Surg Am 1989;71:771-2.
18. Pan G, Kulkarni M, MacDougall DJ, Miner ME. Traumatic epidural hematoma of the cervical spine: diagnosis with magnetic resonance imaging. J Neurosurg 1988;68:798-801.
19. Dahlin PA, George J. Intraspinal hematoma as a complication of anticoagulant therapy. Clin Pharmacol 1984;3:656-61.
20. Williams KN, Jackowshi A, Evans PJD. Epidural haematoma requiring surgical decompression following repeated cervical epidural steroid injections for chronic pain. Pain 1990;42:197-9.
21. Connolly ES, Winfree CJ, McCormick PC. Management of spinal epidural hematoma after tissue plasminogen activator. Spine 1996;21:1694-8.
22. Boukobza M, Guichard JP, Boissonet M, et al. Spinal epidural haematoma: report of 11 cases and review of the literature. Neuroradiology 1994;36:456-9.
23. Owens EL, Watson GW, Hessel EA. Spinal subarachnoid hematoma after lumbar puncture and heparinization: a case report, review of the literature, and discussion of anesthetic implications. Anesth Analg 1986;65:1201-7.
24. Louville Y, Cazalaa J-B. Spinal anesthesia and heparin antithrombotic prevention [in French]. Agressologie 1990;31:160-3.
25. Sage DJ. Epidurals, spinals and bleeding disorders in pregnancy: a review. Anaesth Intensive Care 1990;18:319-26.
26. Joseph AP, Vinen JD. Acute spinal epidural hematoma. J Emerg Med 1993;11:437-41.
27. Klossek H, Huller E. Zur Problematik der spontanen spinalen Epiduralhamatome. Zentralbl Neurochir 1984;45:116-23.
28. Foo D, Rossier AB. Preoperative neurological status in predicting surgical outcome of spinal epidural hematomas. Surg Neurol 1984;15:389-401.
29. Tryba M. Epidural regional anesthesia and low molecular heparin: pro [in German]. Anaesth Intensivmed Notfallmed Schmerzther 1993;28:179-81.
30. Baron HC, LaRaja RD, Rossi G, Atkinson D. Continuous epidural analgesia in the heparinized vascular surgical patient: a retrospective review of 912 patients. J Vasc Surg 1987;5:144-6.
31. Vandermeulen EP, Aken VA, Vermylen J. Anticoagulants and spinal-epidural anesthesia. Anesth Analg 1994;79:1165-77.
32. Benzon HT, Brunner EA, Vaisrub N. Bleeding time and nerve blocks after aspirin. Reg Anesth 1984;9:86-9.
33. CLASP. CLASP: a randomized trial of low dose aspirin for the prevention and treatment of pre-eclampsia among 9364 pregnant women. Lancet 1994;343:619-29.
34. de Swiet M, Redman CWG. Aspirin, extradural anaesthesia and the MRC collaborative low-dose aspirin study in pregnancy [letter]. Br J Anaesth 1992;69:109-10.
35. Horlocker TT, Wedel DJ, Offord KP. Does preoperative antiplatelet therapy increase the risk of hemorrhagic complications associated with regional anesthesia? Anesth Analg 1990;70:631-4.
36. Markus JB, Franchetto AA, Fairbrother J. Magnetic resonance imaging and computed tomography of hyperacute spinal epidural hematoma. Can Assoc Radiol J 1994;45:391-3.
37. Rothfus WE, Chedid MK, Deeb ZL, et al. MR imaging in the diagnosis of spontaneous spinal epidural hematomas. J Comput Assist Tomogr 1987;11:851-4.
38. Sze G, Twohig M. Neoplastic disease of the spine and spinal cord. In: Atlas SW, ed. Magnetic resonance imaging of the brain and spine. New York: Raven Press; 1991:921-65.
39. Avrahami E, Tadmor R, Ram Z, et al. MR demonstration of spontaneous acute epidural hematoma of the thoracic spine. Neuroradiology 1989;31:89-92.
40. Jenkins JR, Runge VM. The use of MR contrast agents in the evaluation of disease of the spine. Topics Magn Reson Imaging 1995;7:168-80.