Abstract: BACKGROUND: The nerve root sedimentation sign has improved the imaging understanding of lumbar spinal stenosis as a new assessment index for it, but controversy still exists as to whether the nerve root sedimentation sign affects the prognostic efficacy of total endoscopic lumbar spinal decompression surgery.
OBJECTIVE: To investigate the effect of nerve root sedimentation sign on the efficacy of lumbar spinal stenosis treated by full endoscopic techniques. 
METHODS: Clinical data of 69 patients with lumbar spinal stenosis who underwent full endoscopic lumbar decompression from September 2018 to September 2022 in Jiangsu Provincial Hospital of Integrated Traditional Chinese and Western Medicine were retrospectively analyzed. The patients were divided into positive group (n=45) and negative group (n=24) according to whether the cauda equina was sedated under MRI. The general data, visual analog scale scores for low back pain and leg pain, Oswestry disability index scores and Macnab efficacy ratings of the two groups were compared, and the changes in the sagittal diameter of the lumbar spinal canal, transverse diameter of the spinal canal, the area of the spinal canal, and the angle of anterior convexity of the lumbar spine were compared between the pre- and post-treatment periods.
RESULTS AND CONCLUSION: (1) Postoperative visual analog scale scores and Oswestry disability index scores of the two groups were reduced compared with those of the preoperative period, and the differences were statistically significant (P < 0.05). Comparing the two groups, the scores of the positive group in terms of low back pain were significantly lower than those of the negative group in both the 1-week and the 1-year periods after treatment, and the differences were statistically significant (P < 0.05). (2) The area of the spinal canal, the sagittal diameter of the spinal canal, and the transverse diameter of the spinal canal were significantly enlarged after the operation in both groups compared with the preoperative period, and the difference was statistically significant (P < 0.05). (3) The lumbar anterior convexity angle was not significantly affected in both groups after surgery, and the difference was not statistically significant compared with the preoperative and postoperative periods (P > 0.05). (4) The 1-year postoperative efficacy of the patients was evaluated by MacNab: positive group: 30 cases were excellent, 11 cases were good, 3 cases were average, and 1 case was poor, with an excellent and good rate of 91%; negative group: 16 cases were excellent, 4 cases were good, 4 cases were average, with an excellent and good rate of 83%. No significant difference was detected between the two groups (P > 0.05). (5) The above results show that total endoscopic lumbar spinal canal decompression in the treatment of lumbar spinal stenosis has outstanding efficacy, which can achieve accurate decompression and can be well reflected on MRI, while the presence or absence of nerve root sedimentation sign has no obvious effect on the postoperative efficacy. 

Key words: ">nerve root subsidence sign, lumbar spinal stenosis, full endoscopic technique, MRI, spinal canal area, lumbar lordosis angle, retrospective study