To evaluate outcome in patients with failed back surgery syndrome treated with nerve root sleeve injections.
Design and Patients:
An open, nonblinded, randomized study on 60 patients with documented fibrosis in fewer than three nerve roots.
After random selection, 20 patients were injected with 1 ml bupivacaine 0.5% combined with 1500 units hyaluronidase and 1 ml saline per nerve root sleeve (group A), another 20 were treated with 1 ml bupivacaine 0.5% combined with 40 mg methylprednisolone solution (Depo Medrol) per nerve root (group B), and a third group was treated with bupivacaine 0.5% combined with 1500 units hyaluronidase and 40 mg methylprednisolone solution (group C). The volume of each injection was 2 ml. The injections were given twice at an interval of 1 week.
The patients were evaluated on a verbal pain rating scale 1, 3, and 6 months after the second injection. The Kruskal-Wallis test was used to detect statistically significant differences among the three groups, and the analysis was refined with the Friedman test.
Results and Conclusions:
Overall, although injections induced analgesia at 1 month, these effects were reduced at 3- and 6-month follow-ups. No statistical differences were found between the three treatment groups (after 1 month, p = 0.71; after 3 months, p = 0.69; after 6 months, p = 0.66. The Friedman test showed a significant decrease in treatment score as a function of time in groups B and C (p = 0.015) but not in group A (p = 0.074). Corticosteroids seem responsible for the last phenomenon.