Risk factors for postoperative epidural hematoma after microsurgical decompression of lumbar spinal stenosis.

Introduction: Postoperative spinal epidural hematoma (SEH) is rare but severe complication of lumbar decompression. Previous studies on the risk factors for postoperative SEH are scarce and limited by small sample sizes. Research question: This study aimed to identify the risk factors for postoperative SEH in patients undergoing microsurgical decompression for lumbar spinal stenosis (LSS). Our primary hypothesis was that old age and multi-level surgery are associated with higher risk of SEH. Materials and methods: We retrospectively studied adult patients who 1) underwent microsurgical decompression of LSS (n = 2947), and 2) were re-operated for postoperative SEH (n = 68, 2.3% of all cases). A cohort of patients who underwent decompression and did not develop SEH matched by age (age-matched controls, n = 135) and number of levels operated (level-matched controls,n = 131) formed the two control groups. Results: There were no differences in median age between the patients who developed SEH and their level-matched controls (69 vs 66 years). The proportion of multi-level procedures was higher (37% vs 24%) among those who developed SEH. In the multivariate logistic regression analyses, preoperative hypertension diagnosis (both between SEH patients and 1) age- and 2) level-matched controls) and longer duration of surgery (only between SEH patients and level-matched controls) were associated with an increased risk of postoperative SEH. Discussion and conclusion: Preoperative hypertension diagnosis and prolonged duration of surgery were associated with higher risk of postoperative SEH among patients undergoing lumbar microsurgical decompression. Special attention to intraoperative hemostasis is mandatory in all patients, not only in those with these risk factors.