Piriformis syndrome: comparison of the effectiveness of local anesthetic and corticosteroid injections: a double-blinded, randomized controlled study

Abstract

Background: Piriformis syndrome (PS), which is characterized by pain radiating to the gluteal region and posterior leg, is accepted as one of the causes of sciatalgia. Although the importance of local piriformis muscle injections whenever PS is clinically suspected has been shown in many studies, there are not enough studies considering the clinical efficacy of these injections.

Objective: To investigate the differences between local anesthetic (LA) and LA + corticosteroid (CS) injections in the treatment of PS.

Study design: A prospective, double-blinded, randomized controlled trial.

Setting: Physical medicine and rehabilitation department of a university hospital.

Methods: Fifty-seven patients having unilateral hip and/or leg pain with positive FAIR test and tenderness and/or trigger point at the piriformis muscle were evaluated. Out of 50 patients randomly assigned to 2 groups, 47 patients whose pain resolved at least 50% from the baseline after the injection were diagnosed as having PS. The first group (n = 22) received 5 mL of lidocaine 2% while the second group (n = 25) received 4 mL of lidocaine 2% + 1 mL of betametazone under the guidance of ultrasound.

Outcome assessment: Numeric Rating Scale (NRS) and Likert Analogue Scale (LAS).

Results: No statistically significant difference (P > 0.05) was detected between the groups in NRS score values at resting (P = 0.814), night (P = 0.830), and in motion (P = 0.145), and LAS values with long duration of sitting (P = 0.547), standing (P = 0.898), and lying (P = 0.326) with evaluations at baseline, first week, and first and third months after the injection. A statistically highly significant (P < 0.005) reduction of pain was evaluated through NRS scores at resting (P = 0.001), in motion (P = 0.001), and at night (P = 0.001) and LAS values with long duration of sitting (P = 0.001), standing (P = 0.001), and lying (P = 0.001) in both of the groups.

Limitations: Presumed limitations of this study include having a relatively small sample.

Conclusion: LA injections for the PS were found to be clinically effective. However, addition of CS to LA did not give an additional benefit. This gives us the idea that PS is mostly muscular in origin and responds well to both LA and LA+CS injections.