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
may be 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 valveless 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