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.