Remodeling of Epidural Fluid Hematoma after Uniportal Lumbar Endoscopic Unilateral Laminotomy with Bilateral Decompression: Comparative Clinical and Radiological Outcomes with a Minimum Follow-up of 2 Years

STUDY DESIGN: Retrospective cohort study. PURPOSE: To evaluate the clinical and radiological effects of epidural fluid hematoma in the medium term after lumbar endoscopic decompression. OVERVIEW OF LITERATURE: There is limited literature comparing the effect of postoperative epidural fluid hematoma after uniportal endoscopic decompression. METHODS: Magnetic resonance imaging (MRI) and clinical evaluation were performed for patients with single-level uniportal endoscopic lumbar decompression with a minimum follow-up of 2 years. RESULTS: A total of 126 patients were recruited with a minimum follow-up of 26 months. The incidence of epidural fluid hematoma was 27%. Postoperative MRI revealed a significant improvement in the postoperative dura sac area at postoperative day 1 and at the upper endplate at 6 months in the hematoma cohort (39.69±15.72 and 26.89±16.58 mm(2)) as compared with the nonhematoma cohort (48.92±21.36 and 35.1±20.44 mm(2)), respectively (p<0.05); and at the lower endplate on postoperative 1 day in the hematoma cohort (51.18±24.69 mm(2)) compared to the nonhematoma cohort (63.91±27.92 mm(2)) (p<0.05). No significant difference was observed in the dura sac area at postoperative 1 year in both cohorts. The hematoma cohort had statistically significant higher postoperative 1-week Visual Analog Scale (VAS; 3.32±0.68) pain and Oswestry Disability Index (ODI; 32.65±5.56) scores than the nonhematoma cohort (2.99±0.50 and 30.02±4.84, respectively; p<0.05). No significant difference was found at the final follow-up VAS, ODI, and MRI dura sac area. CONCLUSIONS: Epidural fluid hematoma is a common early postoperative MRI finding in lumbar endoscopic unilateral laminotomy with bilateral decompression. Conservative management is the preferred treatment option for patients who do not have a neurological deficit. Symptoms last only a few days and are self-limiting. A common endpoint is a remodeled fluid hematoma and the subsequent expansion of the dura sac area.