Predictors of Successful Outcomes of Selective Nerve Root Blocks for Acute Lumbar Disc Herniation

Study Design: Prospective, observational cohort study. Objective: Selective nerve root block (SNRB) is an effective, standard interventional procedure for failed medical management in lumbar disc herniation (LDH). However, the factors that would predict successful outcomes in patients undergoing SNRB have not been clearly studied. Methods: Patients with failed conservative treatment for acute LDH, treated with SNRB were periodically followed till 1 year. Patients who failed to have pain relief or had recurrent pain after SNRB, underwent surgery. The pattern of radiculogram during SNRB was classified into 4 types-"arm," "arrow," "linear," and "splash." Various clinical factors, radiological factors, and radiculograms were compared between patients who had consistent pain relief (group A) and those patients who did not (group B). Results: A total of 91 patients underwent SNRB. Sixty-nine had good pain relief maintained till 1 year (75.8% success). Twenty-two patients underwent surgery after failed NRB at a mean of 6.3 weeks. Patients with sensory symptoms (P = .01), higher mean preinjection Oswestry Disability Index (ODI) score (P = .02), higher mean postinjection ODI score at 3 weeks (P = .004), nonmanual job (P = .01), lumbosacral transitional segment (P = .00 005), and splash pattern of radiculogram (P = .005) were predictive of failed NRB. Logistic regression analysis showed that lumbosacral transitional segment at the level of LDH is the most significant factor predicting poor outcome. Conclusions: SNRB is an effective technique to provide consistent symptom relief at least till 1 year in patients with acute LDH. The study identified several factors that predicted poor outcomes of SNRB and such patients can be forewarned about need for later surgery.