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.
Key words: Piriformis muscle syndrome, injection, ultrasound, pain, local anesthetics, steroids,
rehabilitation
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