• Steven Deschner, MD
• Honorio T. Benzon, MD

       INTRODUCTION

Spinal epidural hematoma (SEH) is an accumulation ofblood in the potential space between the dura and the bone. Hemorrhage into the spinal canal most commonly occurs in the epidural space because of the prominent epidural venous plexus. SEH may be spontaneous or may follow minor trauma, such as lumbar puncture or neuraxial anesthesia. It is more likely to occur in anticoagulated or thrombocytopenic patients, or in those with liver disease or alcoholism. Approximately one quarter to one third of all cases are associated with anticoagulation therapy.^1,2 Spontaneous bleeding is rare but may be seen with anticoagulation, thrombolysis, blood dyscrasias, coagulopathies, thrombocytopenia, neoplasms, vascular malformations, or vertebral hemagioma.^3,4 The peridural venous plexus is usually involved, though arterial sources of hemorrhage also occur.⁵ SEHs are mostly venous in nature because the venous plexus lacks valves, and the plexus has been shown to permit a reversal in blood flow during pressure increase from physical activity.⁶ Hematoma sites are usually found in the cervical and thoracic spine.⁷

Most SEHs are located dorsal to the durai sac because of the firm adherence of the durai sac to the posterior longitudinal ligament in the ventral aspect of the spinal canal. The dorsal aspect of the thoracic or lumbar region is involved commonly, and expansion is limited to a few vertebral levels.

Clinical Pearls

Incidence

SEH represents a rare spinal emergency, with a frequency of less than 1% of spinal space-occupying lesions.⁸ SEH affects 1 per 1,000,000 people annually.^9,10 The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with central neural blockade is unknown. In an extensive review of the literature, the calculated incidence was approximated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthesias.¹¹ No racial predilection has been reported, but SEH is more frequent in females. Increased age has been associated with more frequent SEH.

        Anticoagulant therapy in association with neuraxial analgesia, as well as the length and intensity of anticoagulation, has been identified as one of the most important risk factors for epidural hematoma.¹² Decreased weight and concomitant hepatic or renal disease, which may exaggerate the anticoagulant response, represent theoretical concerns for bleeding tendency. Thrombolytic therapy represents the greatest risk factor for bleeding complications.¹³

History & Physical Examination

The patient is usually in significant distress and usually presents with a severe, localized constant back pain with or without a radicular component that may mimic disc herniation. Associated symptoms may include weakness, numbness, and urinary or fecal incontinence.^14,15 The onset of pain is occasionally related to minor straining such as with defecation, lifting, coughing, or sneezing, but in the majority of cases the onset of pain is spontaneous.^16,17 Signs of spinal cord and nerve root dysfunction appear rapidly and may progress to paraparesis or paraplegia depending on the level of the lesion. In the lumbar spine, the epidural hematoma may mimic an acute disc herniation. In the cases of epidural hematomas that are related to neuraxial anesthesia or lumbar puncture, the presence of new or progressive postoperative neurologic symptoms should alert the physician to a possible epidural hematoma.

Clinical Pearls

        Back pain is enhanced by percussion over the spine, as well as maneuvers that increase intraspinal pressure such as coughing, sneezing, or straining. Depending on the level and the size of the hematoma, physical findings may include unilateral or bilateral weakness, sensory deficits with unilateral or bilateral radicular paresthesias, various alterations in deep tendon reflexes, and alterations of bladder or anal sphincter tone.¹⁸

Etiology & Location of Hematoma

The proposed factors that can cause spinal epidural hematoma include trauma, anticoagulation, thrombolysis, lumbar puncture, epidural or spinal anesthesia, interventional spine procedures or surgeries, coagulopathy or bleeding diathesis, hepatic disease with portal hypertension, vascular malformation, disk herniation, Paget disease of the vertebral bones, Valsalva maneuver, and hypertension.¹⁹ The most important causes of spontaneous spinal epidural hematoma are clotting disorders, which maybe acquired (anticoagulant therapy, malignancies) or congenital (hemophilia).^20–21 Vascular malformations are rarely responsible for spontaneous epidural hematomas; only 4% in a series of 158 cases and 6.5% in a series of 199 cases were reported to be due to vascular malformation.^22,23 Other less common predisposing factors include systemic lupus erythematosus, ankylosing spondylitis, rheumatoid arthritis, Paget disease, disc herniation, and hypertension.^17,24,25 No underlying cause can be identified in about 40% to 50% of cases. The most widely accepted hypothesis is that of venous bleeding. Epidural veins are valve-less and are located in the low-pressure epidural space. These veins are unprotected from sudden increases in intraabdominal or intrathoracic pressure (as in the Valsalva maneuver), leading to rupture and hemorrhage.^26,27 It has been proposed that an increase in venous pressure in the epidural space, in association with the hemodynamic changes of pregnancy, may predispose to rupture of a preexisting pathologic venous wall.^28,29 The epidural venous plexus is most prominent in the thoracic spine.²³ Spontaneous SEH most often is located in the thoracic and cervicothoracic region followed by the thoracolumbar location and extends over a few vertebral body levels.^8,15,16,23 Spinal epidural hematoma is usually posterior or posterolateral to the thecal sac (Figure 71–1).²³

Diagnosis of SEH

Clinical findings of SEH usually include neurologic deficit during the acute stage; the motor and sensory deficits may rapidly develop into paraplegia, quadriplegia, or autonomic dysfunction. Patients usually present with acute axial spine pain that radiates to corresponding dermatomes and evolving focal neurologic deficit with signs of nerve root or spinal cord compression.³⁰ The epidural hematoma usually presents itself within the first 24–48 h after surgery. Early clinical signs are increased pain or focal neurologic deficit, often in areas not present preoperatively or in areas affected by the surgery. Any new or progressive neurologic symptoms warrant immediate clinical evaluation and diagnostic work-up to rule out any space-occupying lesion including epidural hematoma. A new or progressive neurologic deficit occurring in the presence of epidural analgesia mandates immediate discontinuation of the infusion, with the catheter left in place, to rule out any contribution from the local anesthetic. If the epidural infusion is the cause of the neurologic manifestation, a return of sensory and motor function should be noted. Otherwise, an immediate work-up and radiographic imaging studies should be obtained and a consultation with a neurosurgeon sought.

Figure 71–1. Sagittal magnetic resonance images of the thoracolumbar spine. A large complex epidural hematoma extending from T3 to T10 through T11 is seen with hypo- and isodense signal characteristics on a T1-weighted image (left; arrows) and hyperintense signal characteristics on a T2-weighted image (right; arrows). At the center of the hematoma, the spinal cord abuts the posterior aspect of the thoracic vertebral bodies (left

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Regional Anesthesia in the Patient with Preexisting Neurologic Disease. The History of Local Anesthesia. Stimulating Catheters. Ultrasound-Assisted Nerve Blocks in Adults. Histology of Peripheral Nerves. Supraclavicular Brachial Plexus Block.