Spinal epidural hematoma (SEH) is an accumulation of blood in the loose areolar tissue between the vertebrae and the dura of the spinal canal. Typically, the hematoma is asymptomatic, but in rare cases it will compress the spinal cord, with potentially devastating neurological consequences. These symptoms include sensory disruption, bowel and bladder incontinence, motor weakness, or, in severe cases, complete paralysis of the affected limbs. This clinical entity was first described in the medical literature in 1682 as spinal hematoma with spinal apoplexy in the Histoire de l’Academie Royale des Science (Volume 2; G.J. Duverney).1 Nearly 200 years later, in 1869, a report of the first clinical diagnosis of SEH was published in the Lancet.2
The SEHs can be spontaneous in nature or may occur in the setting of an invasive procedure, such as lumbar puncture, neuraxial anesthesia, or spine surgery. Hematoma is more likely to be symptomatic in the cervical and thoracic regions, given the constricted spinal canal in this area compared to the greater space available for volume compensation in the lumbar and particularly the cauda equina region.3
Symptomatic SEH accounts for less than 1% of all spinal space-occupying lesions4 and affects only 1 per 1 million people annually.5,6 SEHs arise from myriad etiologies but most often from a procedure performed in or near the epidural space. For example, the presence of SEH can be found on postoperative imaging in 33% to 100% of patients after spinal surgery,7 but patients will rarely show any neurologic deficit. A 2010 systematic review found an overall calculated incidence of symptomatic SEH after spine surgery of 0.2%, with individual study calculations ranging between 0% and 1.0%.8 Therefore, the incidence of SEH is routinely quoted as the incidence of symptomatic SEH; henceforth in this chapter, the qualifying term symptomatic is implied.
The incidence of SEH after neuraxial anesthesia has historically been approximated to be less than 1 in 150,000 epidural placements and less than 1 in 220,000 spinal anesthetics.9 However, according to recent epidemiologic studies, the incidence may be increasing.10 This estimation was confirmed by a large-scale Swedish study that found an incidence of SEH after epidural blockade of 1:18,000, a figure that results from the average of an obstetric incidence of 1:200,000 and a remarkably high incidence of 1:3600 calculated in a population of elderly female patients undergoing knee arthroplasty.11 Another study showed an overall SEH incidence of 1:4741 that increased to 1:1000 if the population assessed was narrowed to include only elderly women undergoing lower extremity surgery.12 This large disparity can be attributed to the presence or absence of risk factors in these incongruent patient populations. Pregnancy induces a relatively hypercoagulable state and obstetric patients are also younger with a larger and more compliant epidural space than elderly ...