LAUSR

BACKGROUND In this randomized prospective study, we compared surgical invasiveness through a quantitative volumetric analysis of postoperative paravertebral muscle signal intensity changes between transforaminal full-endoscopic lumbar discectomy (FELD) and open discectomy (OD). METHODS We prospectively collected 50 patients with a single-level lumbar foraminal herniation, an invalidating radicular pain, and adequate imaging (postoperative MRI < 24 hours), who were randomly assigned to FELD (n=25) or OD (n= 25) treatment. Data were collected on age, sex, leg and back pain, complications, and follow-up time. Muscle segmentations were done manually using Slicer-3D software based on postoperative isovolumetric T1-contrast enhanced and T2-STIR weighted scans. Both sequences were processed using multiplanar reconstructions in orthogonal planes. Clinical and demographic characteristics, as well as volumetric data, were then compared between groups. RESULTS We found a higher mean volume of paravertebral muscle signal alterations among OD-treated patients in both T2-STIR weighted MRI (p-value=<0.001) and T1-contrast enhanced MRI (p-value=<0.001) scans, compared to FELD. No differences between median preoperative and postoperative leg pain were found between the two groups (p-value=1.000). Median values for postoperative back pain were significantly lower for FELD patients (p-value=<0.001), as long as the median time from operation to patients autonomous mobilization (p-value=0.001). CONCLUSIONS We highlighted a significant difference in signal intensity of paravertebral muscles between FELD and OD patients, which is reflective of the minor surgical invasiveness of endoscopic discectomy. FELD results in less trauma to the paraspinal muscles, possibly also reducing inflammatory cytokine release, and, therefore, is a valuable tool for a spinal surgeon.