The effectiveness of clonidine-bupivacaine repeated nerve stimulator-guided injection in piriformis syndrome.

OBJECTIVES: Piriformis syndrome (PS) is often refractory to conventional therapies. Guided injection techniques generally necessitate a computed tomography or fluoroscopic guidance that may not be available in most pain management centers in addition to its relative high cost. The aim of this clinical trial is to investigate whether clonidine-bupivacaine nerve-stimulator guided injections are effective in achieving long-lasting pain relief in PS compared with bupivacaine guided injection. METHODS: A pilot study conducted on 18 patients (15 females, 3 males) diagnosed with PS showed the adequacy of nerve stimulator guided technique assessed via confirmatory visualized tomography scan demonstrating a worthy coverage of the piriformis muscle in about 84% of the cases. This randomized double-blind trial included 80 patients with PS who received a nerve stimulator-guided piriformis injection (group C received 9 mL bupivacaine 0.5% and 1 mL clonidine 150 mcg/mL; group B received 9 mL bupivacaine 0.5% and 1 mL saline). Pain characteristics and analgesics consumption were the primary end points assessed for 6 months. RESULTS: Group C showed significantly lower pain scores and analgesics consumption than group B (P<0.0001). Pain at 6 months was significantly greater in group B (78%) than in group C (8%) (P<0.01). For every 18 months of PS pain, the outcomes demonstrated that a patient needed 1 additional injection to the initial injection. DISCUSSION: Repeated clonidine-guided piriformis injection relieved PS symptoms and reduce analgesic consumption for a 6-month period. It is a cost-effective useful treatment for PS refractory to traditional therapeutic approaches.

Thoracic paravertebral block: influence of the number of injections.

BACKGROUND AND OBJECTIVES: The purpose of this study was to assess the radiographic and clinical distribution of 1 to 4 paravertebral injections by use of the same total volume of local anesthetic mixture. METHODS: Sixty-nine patients scheduled for surgical interventions suitable for bilateral PVB were included in the study and were randomly assigned to 1 of 3 treatment groups. Group 1 received 4 paravertebral injections on one side versus 1 injection on the contralateral side (23 patients), group 2 received 4 injections versus 2 injections (23 patients), and group 3 received 4 injections versus 3 injections (23 patients). RESULTS: Sixty-one patients were included in the final analysis, which resulted in 368 thoracic paravertebral injections. Overall, 97% of the patients had adequate loss of sensation within the targeted area at the side of 4 injections, compared with only 11% for the single injections. The average vertical spread of contrast was found to be significantly greater in the set of 4 injections, with mean (SD) 6.5 (2.01) dermatomes, compared with the single injection, with 3.0 (1.19) dermatomes (P < .05). The average vertical spread of contrast and complete absence of sensation were significantly greater in the set of 4 injections compared with the set of 2 and 3 injections (P < .05). CONCLUSION: The main finding of the present study was that multiple paravertebral injections resulted in more reliable radiographic and clinical distribution compared with a single-injection technique.