The effect of repeated epidural sympathetic nerve block on "failed back surgery syndrome" associated chronic low back pain

Study Objective: To assess the therapeutic benefits of repeated epidural lo cal anesthetic administration on pain perception and straight leg raise (SL R) in patients suffering from chronic low back pain. Design: Prospective, randomized, controlled, single-blind study protocol. Patients: 50 ASA physical status I, II, and III patients at least 18 years of age, who had previously undergone spine surgery. Interventions: All participants were admitted to hospital for the 5-day dur ation of the study. Following epidural catheterization, fluoroscopy was per formed to verify correct placement of the epidural catheter. On the first s tudy day, all patients received depomedrol 80 mg, in 10-ml 1% lidocaine, ep idurally. Thereafter, patients were randomized into two equal groups. In Gr oup Bupivacaine (B) 10-ml 0.125% bupivacaine was administered. In Group Sal ine (S), an equal volume of saline was administered. Epidural injections we re preformed twice daily (09H00 and 14H00) for 4 days. Sympathetic blockade was confirmed by the presence of peripheral vasodilatation. Sensory blocka de was assessed using loss of pin prick and temperature sensation. SLR as w ell as patient-generated 100-mm visual analog score (VAS) for pain were per formed prior to each injection, at 15 minutes after injection, and hourly f or 2 hours thereafter. Similar parameters were measured 1 week, 1 month, an d 3 months after discharge. Measurements and Main Results: 46 patients completed the study. VAS for pai n was marginally lower in Group B. However, statistical significance was no t demonstrated. During the hospitalization period, the SLR in both study gr oups significantly (0.008) improved with time. However, no difference betwe en the groups was demonstrated. In both groups, 1 week, 1 month and 3 month s after discharge, the SLR was comparable to prestudy recordings. In Group B, at 1 week, 1 month, and 3 months after discharge, patient-generated VAS for pain were significantly (p = 0.002) higher when compared to pain scores at the time of patient discharge. Conclusion: Repeated lumbar epidural blockade does not decrease pain or imp rove SLR in "failed back surgery syndrome." (C) 1999 by Elsevier Science In c.