Prevalence of priformis syndrome in sciatica patients: Predictability of specific tests and radiological findings for diagnosis

Abstract

Background: The traditional approach for diagnosing piriformis syndrome (PS) is to rule out other causes of sciatica. This approach may lead to unnecessary radiological examinations and a waste of time. In contrast to the traditional approach, we aimed to first exclude PS and determine its prevalence by injecting patients with priformis tenderness.

Methods: This observational cross-sectional study included patients diagnosed with PS who had sciatica and tenderness on palpation of the priformis muscle and whose pain was reduced by at least 50% with local injection. Age, sex, pain duration, presence of tenderness in the piriformis muscle, Freiberg test, PACE sign, FADIR, Visual Analog Scale (VAS) score, Douleur Neuropathique 4 Questions (DN4) score, and radiological findings were compared between patients who responded and those who did not respond to the priformis injection.

Results: A total of 110 patients with sciatica were evaluated, of whom 66 with tenderness on palpation of the primiformis muscle underwent local injection. In 27 of the 66 patients (40.9%), a decrease in the NRS score of >50% was observed after injection, and PS was diagnosed. There were no statistically significant differences in age, sex, pain duration, Pace, FADIR test positivity, radiological findings, NRS, and DN4 scores, but Freiberg test positivity was statistically higher in patients diagnosed with PS.

Conclusion: PS is more common than is thought to be a cause of sciatica. A positive Freiberg test is predictive for the diagnosis of PS, but it should be confirmed by tenderness of the priformis muscle and local injection. Many pathologies can be detected incidentally radiographically in PS; however, they are not predictive of the diagnosis.

Keywords: Flexion-adduction-internal rotation; Freiberg; PACE sign; low back pain; piriformis syndrome; sciatica; trigger point injection.