Evaluation of postoperative spinal epidural hematoma after microendoscopic posterior decompression for lumbar spinal stenosis: a clinical and magnetic resonance imaging study

Object. The incidence of postoperative spinal epidural hematoma (SEH) is low, and to the best of the authors' knowledge, no researchers have evaluated its actual incidence and clinical features. The purpose of this study was to investigate the clinical consequences of SEH after microendoscopic posterior decompression (MEPD) in patients with lumbar spinal stenosis. Methods. Data obtained in 30 patients undergoing MEPD for lumbar spinal stenosis were reviewed. At I week after surgery, magnetic resonance (MR) imaging documented SEHs in 10 patients (33% [Group 1]) and no evidence of SEHs in 20 patients (67% [Group 2]). The authors compared MR imaging findings, postoperative morbidities, and clinical outcomes between the groups. Three Group 1 patients had symptomatic SEHs. All symptoms were mild without associated neurological deterioration and spontaneously subsided within 3 weeks of surgery. Magnetic resonance imaging demonstrated spontaneous regression of the SEH in all patients at 3 months after surgery. In Group 1 patients, however, the authors observed less expansion of the dural sac after 1 year despite sufficient widening of the osseous spinal canal. Low-back pain within 1 week of surgery was moderate in Group 1 and mild in Group 2. Improvements at the final follow up were greater in Group 2 patients. Conclusions. The incidence of postoperative SEHs may be greater than reported. Postoperative SEHs caused poor expansion of the dural sac despite its spontaneous regression. In addition, postoperative SEHs caused a delay in the patient's recovery and led to a poor clinical improvement. The prevention of postoperative SEHs might be required to prevent not only neurological deterioration but also a delay in the patient's recovery.