Evaluation of Postoperative Spinal Epidural Hematoma After Biportal Endoscopic Spine Surgery for Single-Level Lumbar Spinal Stenosis: Clinical and Magnetic Resonance Imaging Study

Symptomatic postoperative spinal epidural hematoma is a serious complication that may occur after lumbar spine surgery. We analyzed epidural hematoma using postoperative magnetic resonance imaging (MRI) after biportal endoscopic spinal surgery and its impact on clinical outcome.The subjects of this study were 158 patients who underwent single-level decompression using the biportal endoscopic spinal surgery technique from 2015 to 2017. MRI was performed in all patients before and after surgery, and postoperative MRI was used to identify epidural hematoma. The preoperative and postoperative visual analog scale (VAS) score for leg and back pain, Oswestry Disability Index (ODI), and modified Macnab criteria were recorded for evaluation of clinical outcome. The group with postoperative spinal epidural hematoma (group A) and without hematoma (group B) were comparatively analyzed, both radiologically and clinically.The mean age of the patients was 67.9 ± 11.1 years (range, 49-89). The total number with grade 0 (no hematoma) was 119 levels patients (75.3%) on the T2 axial image of postoperative MRI. The total number of patients with hematoma was 39 (24.7%) according to T2-weighted axial postoperative MRI. Two patients underwent revision surgery because of hematoma-related symptoms. The improvement of clinical outcome measures including VAS leg, VAS back, and ODI was significantly different between group A and B (P < 0.05).The incidence of postoperative spinal epidural hematoma after biportal endoscopic spinal surgery according to postoperative MRI was higher than expected, regardless of the patients' postoperative symptoms. Postoperative hematoma has a decisive influence on postoperative results, and revision surgery might be necessary if canal encroachment is >50% with concomitant symptoms.