Postoperative symptomatic epidural hematoma (SEH) is a serious complication of lumbar spine surgery. Despite its rarity, this uncommon complication may result in devastating neurological sequelae, including lower limb weakness.

A retrospective study was made to identify possible risk factors of postoperative spinal epidural hematoma by reviewing the clinical cases of this rare complication and analyzing the postoperative evaluations of patients.

From 2002 to 2010, out of 15,562 who underwent lumbar decompression procedure with/without instrumentation, 25 patients required reoperation for epidural hematoma after the initial spinal surgery. For the control group, another 75 patients were randomly selected from the pool of patients who received lumbar decompression surgery during the same period of time. The medical records of preoperative, intraoperative and postoperative factors were collected to determine possible risk factors by comparing between the cases and controls, and the postoperative evaluations of muscle power, intractable pain, saddle anesthesia, time to detection and time to evacuation were analyzed to find if there is any significant relation within the case group. Mann-Whitney U test, two-sample t test, χ (2) test and Fisher's exact test were used for statistical analysis.

The incidence of postoperative symptomatic epidural hematoma is 0.16%. After the initial procedure, 20 (80%) patients developed progressive decrease in muscle power (MP ≤ 3), 14 (56%) patients had intractable pain (VAS ≥ 7), and 19 (76%) patients had saddle anesthesia. Preoperative diastolic blood pressure, intraoperative use of gelfoam for dura coverage and postoperative drain output were statistically significant risk factors (p < 0.01). Within the SEH case group, postoperative symptom of decreased muscle power had significant relation with blood loss, laminectomy level and fusion level (p = 0.016, 0.021, 0.010). If the symptom of decreased muscle power or perianal anesthesia was not improved after hematoma evacuation, there was a tendency for permanent leg weakness after 1-year follow-up (p = 0.001, 0.003).

The findings suggest that preoperative diastolic blood pressure, intraoperative use of gelfoam for dura coverage and postoperative drain output are risk factors for symptomatic epidural hematoma after lumbar decompression surgery. Major blood loss and multilevel surgical procedure could result in poor recovery of muscle power. After spine decompression surgery, early detection and evacuation of hematoma are the key to avoid neurologic deterioration and have better clinical outcomes.