Delayed Onset Postoperative Spinal Epidural Hematoma after Lumbar Spinal Surgery: Incidence, Risk Factors, and Clinical Outcomes

BACKGROUND: Posterior spinal epidural haematoma (PSEH) often develops within 24 hours after surgery. On rare occasions, PSEH occurs after 3 days and up to two weeks and is classified as delayed-onset PSEH. Due to its rarity, previous studies have only described the clinical features, whereas risk factors have not been assessed. METHODS: Patients who developed PSEH requiring haematoma evacuation between December 2013 and January 2020 were included and divided into the early-onset (group A) and delayed-onset (group B) groups based on the time of symptom onset (>72 hours). For each PSEH patient, 3 controls (group C) who did not develop PSEH in the same period were randomly selected. Clinical features were compared among the three groups, and multiple logistic regression analysis was performed to identify the risk factors for groups A and B. RESULTS: Thirty-two patients (0.35%) were identified as having early-onset PSEH (occurring at 10.68 ± 11.5 h), and 15 (0.16%) patients had delayed-onset PSEH (occurring at 130.60 ± 61.78 h). When comparing groups A and B, group A showed a higher rate of multilevel procedures, lower drainage, lower APTT, and higher JOA score at discharge. Multiple logistic regression analysis identified multilevel procedures (OR: 5.62, 95% CI: 1.84-17.25), postoperative systolic blood pressure (SBP) (OR: 1.10, 95% CI: 1.06-1.15), and abnormal coagulation (OR: 5.68, 95% CI: 1.74-18.52) as independent risk factors for group A, whereas postoperative SBP (OR: 1.10, 95% CI: 1.04-1.16) and previous spinal surgery (OR: 4.74, 95% CI: 1.09-20.70) at the same level were risk factors for group B. CONCLUSIONS: Our study revealed that the overall incidence of delayed-onset PSEH was 0.16% in posterior lumbar spinal surgery and that its risk was different from that of early-onset PSEH. If patients with such risk factors develop neurological deficits 3 days after initial surgery, surgeons should be aware of the possibility of delayed-onset PSEH.