Objective:To evaluate the guiding value of ultrasound-guided selective nerve root block in the surgical treatment of multilevel lumbar degeneration.Methods:Retrospective case-control study was used. Clinical data of 47 patients with multi-level lumbar degeneration who underwent decompression surgery in Honghui Hospital, Xi′an Jiaotong University from January 2019 to December 2021 were retrospectively analyzed. They were divided into nerve root block group ( n=22)and non-nerve root block group( n=25) according to whether ultrasound-guided selective nerve root block was performed before decompression surgery. The operation time, intraoperative blood loss, number of decompression laminae, postoperative drainage volume and length of stay of the two groups were recorded and compared. The visual analogue scale of low back pain, the visual analogue scale (VAS) of leg pain, the Japanese orthopaedic association (JOA) score and Oswestry disability index (ODI) score were all compared before surgery and during follow-up between the two groups. Measurement data with normal distribution were represented as mean±standard deviation( ± s), and the comparison between groups was conducted using the paired t-test. Chi-square test was used for counting data. Results:All 47 patients successfully completed the operation without any serious complications such as neurovascular injury. All patients were followed up for (27.6±7.5)months. In the nerve root block group, the operation time, intraoperative blood loss, number of decompression laminae, postoperative drainage volume and hospital stay were (90.5±12.6) min, (110.5±15.8) mL, 1.2±0.8, (85.6±15.8) mL, (6.2±2.8) d, respectively. In the non-root block group, they were (190.6±25.5) min, (450.5±24.8) mL, 3.8±1.6, (210.5±16.8) mL, (9.5±2.2) d, respectively. The above indexes in the nerve root closure group were less than those in the non-root closure group, and the difference was significant between the two groups ( P< 0.05). The scores of VAS of low back pain and leg pain, JOA and ODI in both groups were significantly improved after surgery and during the follow-up period when compared with those of pre-operation ( P< 0.05). The VAS scores of low back pain on the 3rd day, 6 months after operation and at the last follow-up in the nerve block group were 3.2±1.4, 1.4±0.8, 0.5±0.2, the JOA scores were 15.8±4.3, 21.3±5.6, 25.6±1.4, and the ODI scores were 50.6±10.3, 22.8±7.8, 16.8±4.2, respectively. The VAS scores of low back pain on the 3rd day, 6 months after operation and at the last follow-up in the non-nerve block group were 5.1±1.8, 3.4±1.2, 1.8±0.5, the JOA scores were 14.1±4.8, 20.5±3.2, 24.2±1.8, and the ODI scores were 60.5±9.8, 31.6±8.2 and 21.3±5.5, respectively. The difference between the two groups was statistically significant ( P<0.05). However, there was no statistical difference in the VAS scores of leg pain between the two groups after surgery and during follow-up ( P>0.05). At the last follow-up, the internal fixation position of the two groups was good, no loosening and displacement, and bone graft fusion was good. Conclusion:For patients with multi-level lumbar degeneration, ultrasound-guided selective nerve root block before surgery can identify the responsible segment, and selective decompression and fusion based on this can effectively reduce surgical trauma, while improving patients′ back and leg pain and physical function, which has important surgical guidance value.