Diagnostic Accuracy of Clinical Tests and Diagnostic Criteria for Piriformis Syndrome

Piriformis syndrome is one of the possible causes of buttock pain and sciatica-like symptoms; however, its diagnosis is often difficult because of symptom overlap with lumbar radiculopathy, sacroiliac joint disorders, and other musculoskeletal conditions. In clinical practice, several physical examination maneuvers and diagnostic criteria are used, but their diagnostic accuracy has not been sufficiently established. The aim of this study is to evaluate the diagnostic accuracy of predefined diagnostic criteria and commonly used clinical tests for piriformis syndrome. Adult participants with suspected piriformis syndrome will be recruited prospectively. All participants will undergo a standardized clinical assessment including history taking, physical examination, and evaluation of predefined diagnostic criteria and provocation tests. Clinical examinations will be performed by two physicians according to the study protocol. As the reference diagnostic procedure, participants will undergo ultrasound-guided injection of 5 mL of 2% lidocaine into the piriformis muscle. The injection will be performed by an experienced physician under ultrasound guidance. Pain severity will be assessed before and after the procedure. A decrease of 50% or more in pain following injection will be accepted as confirmation of piriformis syndrome. The diagnostic performance of each clinical test and diagnostic criterion set will be evaluated against this reference standard. Sensitivity, specificity, predictive values, likelihood ratios, and overall diagnostic accuracy will be analyzed. The findings of this study are expected to contribute to the development of a more standardized, reliable, and clinically applicable diagnostic approach for piriformis syndrome.