MATERIAL and METHODS: We retrospectively analyzed data of patients who underwent our modified SSNBs before PETLS from February 2013 to March 2018 Clinical outcome data were collected 3 days after PETLS and at follow-up visits.

RESULTS: A total of 120 modified SSNB procedures (transforaminal-78 paravertebral-24, and interlaminar-18) in 92 patients presented positive response. The median follow-up period was 30.6 months. Based on Macnab criteria, the overall success rate (excellent and good results) was 83.7%. Fair and poor outcomes were observed in 10 and 5 patients, respectively. Patients with atypical extraforaminal herniations, and patients with two-level or multiple-level lumbar disc herniations or stenosis achieved desirable results after PETLS. There was significant improvement in the average VAS score for the leg three days after surgery (7.38±0.97 vs. 1.96 ±1.17, p<0.05) and on follow-up visits (1.21 ± 0.83, p<0.05). ODI was also significantly improved three days after surgery (37.20 ± 2.36 vs. 10.95 ± 2.25, p<0.05 and at follow-up visits (8.90 ± 1.72, p<0.05)

CONCLUSION: The needle tip should be located closely near the intended compressed nerve via suitable approach combined with slowly injecting 1 ml lidocaine (1%) when performing our modified SSNB technique. It presents an alternative diagnostic procedure to identify the origin of pain of complicated lumbar diseases and to predict PETLS outcomes. Keywords : Selective spinal nerve block (SSNB), Selective spinal root block (SSRB), Percutaneous endoscopic transforaminal lumbar surgery (PETLS), Accurate diagnosis, Target spinal nerve